Europäisches Patentamt
(19)
European Patent Office
*EP001229672B9*
Office européen des brevets
(11)
EP 1 229 672 B9
CORRECTED EUROPEAN PATENT SPECIFICATION
(12)
Note: Bibliography reflects the latest situation
(15) Correction information:
(51) Int Cl.7:
Corrected version no 1 (W1 B1)
Corrections, see page(s) 4, 12
H04B 10/10
(48) Corrigendum issued on:
17.11.2004 Bulletin 2004/47
(45) Date of publication and mention
of the grant of the patent:
19.05.2004 Bulletin 2004/21
(21) Application number: 02009329.0
(22) Date of filing: 13.09.1995
(54) Optical data communication and location apparatus
Optisches Datenübertragungs- und Ortungsgerät
Appareil de transmission optique de données et de localisation
(84) Designated Contracting States:
(72) Inventor: Shipley, Robert T.
DE FR GB IT
Oakland, California 94611 (US)
(30) Priority: 21.09.1994 US 309848
(74) Representative: Findlay, Alice Rosemary et al
Lloyd Wise
Commonwealth House,
1-19 New Oxford Street
London WC1A 1LW (GB)
(43) Date of publication of application:
07.08.2002 Bulletin 2002/32
(62) Document number(s) of the earlier application(s) in
accordance with Art. 76 EPC:
95935098.4 / 0 782 796
(56) References cited:
DE-A- 3 119 876
US-A- 5 345 240
US-A- 5 062 151
(73) Proprietor: Hill-Rom Services, Inc.
EP 1 229 672 B9
Batesville, IN 47006 (US)
Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
99(1) European Patent Convention).
Printed by Jouve, 75001 PARIS (FR)
EP 1 229 672 B9 (W1B1)
Description
[0001] This invention relates to an optical data communication and location apparatus, system and method and
transmitters and receivers for use therewith.
5
Background of the Invention
10
15
20
25
30
35
40
45
50
55
[0002] Communications systems heretofore have employed fixed band and spread spectrum radio frequency (RF)
energy. However, radio based systems which have included portable transmitters suffer from serious drawbacks including their susceptibility to other RF noise sources; overcrowding of RF channels; and, the unpredictability of areas
where reception is interrupted by the construction materials used in the building. Further, the use of RF systems for
locating mobile items or individuals through triangulation does not yield a practical system due to lack of resolution
and the time delay in the many calculations required. RF locating systems are also not cost effective for use inside a
building, owing to their complexity. Other portable location system utilized ultrasonics to transmit the data. Ultrasonic
energy for data communication and locating systems have been found to be impractical because of echoes and data
errors from ambient noise. The ultrasonic transducers used are generally fragile. Only low data rates are achievable
because of relatively low ultrasonic bandwidth. Infrared systems, although portable, have awkward weight and sizes
with limited battery life limiting widespread usage.
[0003] To permit the use of a battery of even the relatively large size and capacity, transmitted infrared power had
to be held to a low value. However, to realize a reasonable signal-to-noise level at the receiver, line-of-sight signal
paths over a controlled distance between the infrared transmitter and receiver were proposed. Such line-of-sight systems require aligning the transmitter and the receiver to establish and maintain the transmission path during the entire
period of transmission. This was proposed to be accomplished by mounting a fixed receiver over a doorway to look
vertically downward. The transmitter was to be worn in a pocket of a wearer positioned to emit infrared signals upward.
For such a system to function, transmissions had to be frequent enough and of short enough duration so as to allow
the receiver to detect a full transmitted message during the period of time that the transmitter moved through the
doorway. A diffuse infrared system is shown in U.S. Patent No. 5,062,151. While the system does not require line-ofsight transmission to achieve portability, the power consumption is so large as to require a multi-cell, rechargeable
battery. A battery sized for portability must be recharged frequently, at least every other day. Aside from the need for
many rechargers and the inconvenience, the requirement for recharging makes locating mobile inanimate objects such
as equipment, files, etc. impractical because of the need to frequently retrieve the transmitter for recharging. The
requirement that the transmitters used to locate personnel be periodically returned to a charger is undesirable, in that
while they are charging for eight to 16 hours, they cannot perform their intended function. Also, if the wearer inadvertently forgets to recharge the transmitter, the transmitter cannot be used until it is recharged. The requirement for a
multi-cell battery sets a lower limit on the size and weight of the portable transmitter making it more cumbersome to
wear or more difficult to attach to small, mobile objects.
[0004] In the system disclosed in U.S. Patent 5,062,151, the first and only notification that a battery charge is becoming depleted is that the person or object associated with the transmitter can no longer be located. To add a battery
checker to detect a low battery without the battery checker itself adding significantly to the drain on the battery being
monitored presents a problem.
[0005] It is known that transmitting data using infrared pulses in lieu of modulating an infrared carrier frequency can
reduce dramatically the power consumption of the transmitter, and any reduction in power consumption translates into
a smaller battery and a longer useful battery life. The transmitted data of previous infrared systems is comprised of
packets of ones and zeros. The presence of an infrared pulse is interpreted as either a one or a zero. The absence of
a pulse represents the opposite. Data words containing mostly ones (assuming ones are the presence of infrared
pulses) consume vastly more power than those with mostly zeros. The data sent by each such transmitter has a different
quantity of pulses. Therefore, the power consumption of each transmitter is different. This causes the battery recharge
interval to be set at that required for the transmitter which transmits all ones.
[0006] The larger and more complicated the facility, the more the need for portable communication with, and the
locating of personnel and mobile items. However, in previous systems when the quantity of transmitter codes is increased, the quantity of pulses required to define a transmitter increases, and therefore power consumption increases
dramatically. Any additional data such as battery condition further adds to the current drain and resultant reduction in
battery life. Further, the use of DC-to-DC converters to multiply the battery voltage to that necessary to drive infrared
emitters in series wastes considerable power. Any DC-to-DC converter will have losses which reduce battery life. The
obvious alternative of adding batteries in series to achieve the necessary voltage for high power transmissions suffers
from a substantial weight and cost penalty. The use of a resistor in series with the emitters to control current consumes
the battery power, increasing battery size and decreasing battery life.
[0007] Transmitters being portable are susceptible to being lost or damaged. It is therefore desirable to be able to
2
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
easily reprogram replacements. Prior art transmitters had their identification codes programmed with hardware jumpers
or switches. In large systems, the quantity of elements such as switches needed to hard code transmitter data is
impractical and costly. While it was known that the identity codes could be stored in solid state non-volatile memory,
such memory is costly and consumes significant power, adding to battery size and decreasing battery life. Another
factor precluding the use of conventional memory is the complication of programming the identification code. The low
currents and high circuit impedances needed for low power consumption and small battery size make the use of common, low cost, electrical contact material impractical. The infrequent use of contacts for programming causes thin
layers of oxidation and contaminants to coat the contacts, making them unreliable.
[0008] In the communication system disclosed in U.S. Patent No. 5,062,151 the room receiver wiring requirements
were onerous for medium to large size systems. For cable runs of reasonable length, the wire gauge must be large
due to the high current consumption of the receivers on the run. While the parallel address and data busses provide
for the large data throughput required of such a communications system, the large quantity of conductors which must
be connected at each room and at a central logic facility makes the cost of the installed system undesirably high.
[0009] In systems with multiple transmitters, there is a need to prevent successive collisions of transmitted infrared
data from separate transmitters in the same location. An accurate time base is a requirement for asynchronous data
transmission. An accurate, high speed clock is a requirement for low power infrared transmission. It is well known that
quartz crystals, and in some applications, even ceramic resonators provide an excellent and stable time base for such
communication. However, because of their very high stability, once the serial transmissions of two transmitters with
stable clocks begin to collide, they will tend to continue to collide for a very long time. A significant limitation of previous
prior art systems was that they either lacked a method to prevent successive collisions of transmitted infrared data
due to two or more transmitters with synchronized transmit intervals, or lacked a method to detect corrupt data caused
by a collision or they consumed additional power to prevent collisions. Such erroneous data causes the database to
be corrupted. In U.S. Patent No. 5,062,151 successive collisions were prevented by the use of a combination of two
transmit intervals that are unique to each and every transmitter. However, this is cumbersome to program and consumes
additional power during transmission. For systems with a large number of transmitters, there may not be sufficient
quantities of unique transmit interval pairs to assign to each transmitter. There is therefore a need for a new and
improved optical data communication and location system and transmitters and receivers for use in the same.
Object and Summary of the Invention
30
35
40
[0010] In general it is an object of the present invention to provide an optical data communication and location apparatus, system and method and transmitters and receivers for use therewith which provides continuous real time
information on the location of people, equipment, files and other mobile objects in a facility.
[0011] Additional objects and features of the invention will appear from the following description in which the preferred
embodiments are set forth in detail in conjunction with the accompanying drawings.
[0012] In a first aspect of the present invention, there is provided an optical data communication apparatus for a
facility including a receiver located in a location of the facility and a plurality of portable transmitters carried by a corresponding plurality of individuals, characterized by a motion detector located in the location, a plurality of optical
wireless data links that facilitate communication between the receiver and the plurality of transmitters, each transmitter
having a unique identification code, and means for actuating an alarm when an individual is detected in the location
by the motion detector without a portable transmitter having an identification code indicating that the individual is permitted access to the location.
Brief Description of the Drawings
45
[0013]
50
Figure 1 is a schematic diagram of an optical data communication and location apparatus and system incorporating
the present invention which include a central logic unit, a plurality of receivers at various locations and a plurality
of portable transmitters, as well as an infrared programmer and a magnetic programmer.
Figure 2 is a schematic block diagram showing the components of the central logic unit, a receiver and a portable
transmitter utilized in the apparatus and system shown in Figure 1.
55
Figure 3 is a schematic block diagram of the magnetic programmer.
Figure 4 is a schematic block diagram of the infrared programmer.
3
EP 1 229 672 B9 (W1B1)
Figure 5 is a front elevational view of a portable transmitter utilized in the system and/or apparatus of the present
invention.
Figure 6 is a side elevational view looking along the line 6-6 of Figure 5.
5
Figure 7 is a view similar to Figure 5 but showing the front cover removed.
Figure 8 is a view of the back side of the transmitter shown in Figure 5 with the back cover removed.
10
Figure 9 is a schematic block diagram of the electronic circuitry used in the transmitter.
Figure 10 shows a data coding diagram for the present invention.
15
Figure 11 is a data encoding diagram showing the manner in which 3-bit encoded data is produced in the present
invention.
Figures 12A, 12B and 12C show three examples of pulse timing and how they are dealt with.
20
Figure 13 is a schematic floor plan showing the manner in which the system, apparatus and method of the present
invention can be used for locating personnel and movable items.
Figure 14 shows a portable data link using the apparatus and system of the present invention.
25
30
[0014] In general, the optical data communication and location system of the present invention is for use for at least
one location with at least one receiver at said at least one location. A plurality of portable transmitters are provided at
said at least one location. Optical wireless data links are provided for connecting the plurality of portable transmitters
to said receiver. Each of the portable transmitters has means for transmitting data packets and is provided with a power
supply for supplying power to the means for transmitting data packets. The means for transmitting data packets in
each of the transmitters includes means for generating a data code having at least two time frames with each time
frame being divided into at least two data time slots. Each frame consists of exactly one pulse in one data time slot so
that n-bits of binary data can be encoded in the data packet where 2n is equal to the number of data time slots in each
frame.
Detailed Description of Preferred Embodiments
35
40
45
50
55
[0015] More particularly as shown in Figure 1 the system and/or apparatus 21 of the present invention consists of a
central logic unit 22 which can be located in a central location which is connected by a conventional communication
link 23 to a plurality of receivers 24 located at a plurality of locations 26 identified as locations 1, 2 and 3 in Figure 1.
The receivers 24 are adapted to receive optical data from a plurality of transmitters 31 at each location 26 by an optical
link indicated at 32. As ahown in Figure 1, the central logic unit can also be connected to other systems 21 as shown.
The apparatus 21 also includes a magnetic programmer 33 for programming the portable transmitters 31 and an infrared
programmer 34 for programming the receivers 24.
[0016] The central logic unit 22 consists of a communication interface 36 that can be of any suitable type. For example
it can consist of a twisted pair of telephone wires, high speed data communications cable, carrier current over the
building electrical power wiring, low power radio frequency or other means appropriate to the system installation.
[0017] The communication interface 36 is connected to a central processor 37 of a suitable type as for example a
486 microcomputer. The central processor 37 is utilized for receiving data from the receivers 24 processing and scoring
such data for access by other systems 38 through a system interface 39. The other systems 38 can include telephone
systems, intercoms, nurse call systems, inventory control systems, location display systems, computer networks, control systems, security systems, energy management systems, alarm systems and the like. The central processor 37
can also send data to the receivers 24. Such data can be used by the receivers to control speakers, piezo audio
transducers, relays, etc. included in or attached to some or all of the receivers 24. The central logic unit 22 as shown
also includes an audio switch 41 which can be utilized for sending audible messages to the receivers 24 from a voice
synthesizer 42. The audio switch 41 can also be connected to other systems 38 which can include other audio communication systems to provide instant communication over receivers equipped with speakers. The central logic unit
also includes a power supply 43 which is connected to a power interface 44.
[0018] The receiver 24 which typically is in a fixed location includes a photo detector consisting of one or more biased
diodes (not shown) which receive the transmitted optical signals which can be in the form of infrared pulses from a
4
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
transmitter 31. The photo detector 46 converts the infrared signals to electrical signals which are amplified by an
amplifier 47. The amplified electrical signal is supplied to a level detector 48 and simultaneously to a packet decoder
49. In accordance with the present invention, the level detector 48 assigns a code to the electrical signal which is
proportional to the power of the received signal. This code indicating the infrared power level is presented to a main
processor 51. The packet decoder 49 checks the validity of the received code and passes proper codes on to the data
registers 52. The data registers 52 are readable by the main processor 51 which communicates valid received data to
the central logic unit 22 through a communication interface 53 that is connected to the communication interface 36 of
the central logic unit 22. The communication interface 53 can be of the same type as the communication interface 36.
A main processor 51 manages local output control from the receiver as shown by the block 57 which can include
enunciation speakers, lights, relays, locks, displays, etc. under its own program or at the instruction of the central
processor 37 of the central logic unit 22. Local control and enunciation elements can include visual indicators, audible
enunciators, audio switches to local speakers, door releases, data transmitters and the like. The receiver 24 can derive
its power through a power interface 58 from a power interface 44 in the central logic unit 22 over a hard wired cable
system or alternatively from building power of other suitable source.
[0019] Each receiver 24 also includes a timing clock 61 connected to the main processor 51. The receiver 24 also
includes a non-volatile memory 62 for storing its address. This stored address has the advantage of allowing a common
communication pathway between the receivers and the central logic unit 22. receivers 24 can be programmed rapidly
and reliably by utilizing a specially coded infrared transmitter as hereinafter described. The main processor 51 utilizes
the power level code from the level detector circuit 48 to determine the proximity to the transmitter 24 as well as whether
the infrared signals contain a programming command. Upon receipt of a programming code from a transmitter 24, the
main processor 51 stores the identity code into the non-volatile memory 62. The identity code and the physical location
of the receiver 24 can be stored on a portable computer. The computer can then send the programming command and
the identification data to the specially coded portable infrared transmitter 31 via the external input to the user data block
66 in the transmitter 31. The transmitter 31 then programs the receiver with receiver identification data via the infrared
signal.
[0020] In connection with the receiver 24 hereinbefore described, it should be understood that the embodiment described is preferred for many applications. However, it should be understood that many of the functional elements such
as data registers 52, the main processor 51 and the packet decoder 49 can be combined with other functional components for economy purposes and centrally located elsewhere. Some of the elements of the receiver 24 such as the
main processor 51 can be shared by a number of receivers without changing the function of the receiver. The logic
elements shown in the block diagram in Figure 2 have been shown separately for clarity. However, it should be understood they can be integrated for cost and performance reasons if desired.
[0021] The portable transmitter 31 as shown in Figure 2 includes a power supply in the form of a battery 71 which
is connected through a low battery detect circuit 72 to a data packet register 73. The transmitter 31 in accordance with
the present invention is capable of automatically and periodically sending data to a fixed receiver 24. Each portable
or mobile transmitter 31 may also transmit data in response to an external input into the user data block 66. Mobile
transmitters 31 utilized in connection with the present invention provide an optical output which in the case of the
present invention is infrared. The transmitters are of a type which are to be carried by people or mounted on movable
objects and typically include at least one infrared emitting diode which emits a series of infrared pulses. In connection
with the present invention, several diodes as for example three are utilized as hereinafter described to transmit pulses
simultaneously to increase the modulation of the infrared energy level in the area of a room in which the transmitter
31 is located. These infrared diodes are indicated by the block 76 labeled "IR emitter". The emitted pulses are represented by the arrow 77. As hereinafter explained, the emitted pulses form a coded message packet which contains a
code uniquely identifying the transmitter 21 as well as transmitter status information, including condition of the battery
from the low battery detector 72. This information is supplied from the data packet register 73 through a packet timing
block 78 through an output drive 79 connected to the IR emitter 76. The remainder of the message supplied from a
transmitter 31 can contain user data input externally from switches, relays, a microcomputer, a terminal, etc.
[0022] When the transmitter 31 is transmitting automatically and periodically, a slow clock 171 controls the transmit
interval rate. The unique identity code of the transmitter 31 and the transmit interval rate can be externally programmed
into the identification and rate data register 52 as hereinafter explained. To accommodate the possibility of many thousands of transmitters in a system, it is desirable that the programming for the transmitters 31 be fast and reliable and
be accomplished in the manner hereinafter described.
[0023] The slow clock 171 is utilized to enable the fast clock 86 only during transmission. The fast clock 86 is used
to generate the narrow infrared pulses and to create proper signal timing. Identity, status and any user data are assembled into the data packet in the data packet register 73. Packet timing logic 78 shifts the data packet through the
output drive 79 to the infrared emitter 76.
[0024] The infrared transmitter 31 has the capability of transmitting an identification packet at a programmable interval
such as every two seconds. Longer or shorter repetition intervals can be programmed where the speed of movement
5
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
of the transmitter dictates the same. The packet of the transmitter is used to locate the wearer of the transmitter in the
manner hereinafter described. In addition, buttons hereinafter described on the transmitter operate momentary switches 87, 88 and 89 individually or in combination to send messages to the receiver 24 and to the central logic unit 22 as
hereinafter described.
[0025] In order for the infrared data communication system 21 of the present invention to be able to provide accurate
location information at an interval between transmissions from the transmitters 31, the interval must be short enough
to permit detection at a new location for a transmitter when the transmitter 31 is moving. For example, a transmission
interval of every fifteen seconds is typically too long for locating people because in 15 seconds a person can easily
travel between several offices away from the location of the last transmission.
[0026] A specific embodiment of a transmitter 31 incorporating the present invention is shown in Figures 3-6. As
shown therein, the transmitter 31 consists of a case 101 formed of a suitable lightweight material such as plastic and
is provided with front and rear covers 102 and 103 which are rectangular in shape which can be fastened together by
suitable means such as ultrasonic welding. The covers 102 and 103 are rectangular to provide a case 101 which has
a suitable dimension as for example a height of 5,59 cm, a width of 5,08 cm and a thickness of 0,64 cm. The case 101
is provided with a top 106 and a bottom 107 and first and second parallel sides 108 and 109. The case is provided
with a slot 111 which extends through the front and rear covers 102 and 103. A strap 112 formed of a suitable flexible
material such as plastic extends through the slot 111 and is snapped together by a snap fastener 113 of a conventional
type. A metal spring clip 114 of a conventional type is secured to the strap 112 by a rivet 116. Other means of attachment
can be used when the transmitters 31 are to be attached to movable objects, such as a strap having a conductive link
therein which when broken will cause the transmitter to send an alarm message.
[0027] A printed circuit board 121 is mounted within the case 101 and carries the three momentary contact switches
87, 88 and 89 which are aligned in a row and are accessible through the side 109 of the case 101 through cutouts 122
provided in the front and rear covers 102 and 103. The printed circuit board 121 also carries three spaced-apart lightemitting diodes 126 mounted in the upper portion of the printed circuit board 121 which serve as infrared emitters 76
in Figure 2 in accordance with the present invention. The diodes 126 are exposed to ambient through holes 127 provided
in the front cover 102 so that infrared energy emitted therefrom is propagated into a space in a direction extending
forwardly and sideways of the front cover 102 of the case 101. It should be appreciated that the infrared emitters can
be totally enclosed in the case 101 when the case 101 is made of an infrared transparent material such as an acrylic.
The battery 71 in a removable molded holder 131 is inserted into a slot 132 in the lower side 107 of the case 101. The
battery 71 can be of a suitable type as for example a Duracell 3 volt battery identified as DL 2032. The battery 71 is
connected to the printed circuit board 121 by spring loaded contacts (not shown) on the printed circuit board. The
printed circuit board 121 contains a number of dual in-line integrated circuit packages mounted thereon of the type
hereinafter described for performing various functions in the transmitter 31.
[0028] In order to make possible radio frequency magnetic programming of the transmitters 31 as hereinafter described, the printed circuit board 121 is provided with a pair of antenna loops 136 which are etched onto the printed
circuit board 121. The antenna can have a suitable configuration as for example a circular configuration of 6 millimeters
square in diameter and spaced apart a suitable distance as for example 12 millimeters. As hereinafter explained, when
this pair of antenna loops 136 is brought into close proximity to a phased pair of programming antenna, a differential
programming signal is detected and loaded into identification and data register as hereinafter explained. This radio
frequency programming precludes the need for electrical contacts which can become corroded or contaminated. The
elimination of the electrical contacts reduces the cost of the transmitter. The radio frequency programming also permits
programming to be done automatically using a personal computer by establishing a data base with a one-to-one correspondence between user and transmitter identity codes so that programming errors can be prevented.
[0029] The electrical components which are shown on the printed circuit board 121 in Figures 5 and 6 are shown
schematically in the circuit diagram shown in Figure 7. As hereinbefore described, power for the printed circuit board
121 is supplied by the three-volt battery 71 mounted thereon. The battery 71 is a 200 milliampere-hour lithium battery
which as hereinafter explained and with a two-second transmit interval for the transmitter 31 for 24 hours per day will
provide adequate power for approximately one year. Such a transmitter with an eight-second transmit interval would
have sufficient power from such a battery to operate for approximately three years.
[0030] As shown in the lower left margin of the drawing in Figure 7, the battery 71 has its positive terminal connected
to a Vcc terminal 141 and has its negative terminal connected to a ground 142. It is known that a battery such as battery
71 has a relatively high internal impedance to fast, high current pulses. A plurality, as for example three, high frequency
tantalum capacitors 143 are connected in parallel with the battery to bypass high frequency currents to provide a
resultant low impedance to permit the flow of large battery currents to produce high energy pulses. Various other
portions of the circuitry as shown in Figure 7 are connected to the Vcc terminal 141 and to ground 142 to receive power
from the battery 71.
[0031] For transmitters having lower power requirements of the type hereinafter described, an alternative power
source rather than a battery can be utilized. For example, if the system or apparatus 21 of the present invention is
6
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
installed in an urban area, there are multiple sources of radio frequency energy such as from radio stations, cellular
phone systems, etc. for transmitters of the present invention having longer transmit intervals and therefore lower power
requirements. Such transmitters can be powered from radio frequency energy captured by antenna constructed from
multiple turns of wire (not shown) disposed within the interior of the case 101. Where weight and size is not an issue
a conventional antenna can be mounted on the case 101 to pick up the radio frequency energy. For transmitters which
need not operate in dark locations, the transmitters can be powered from a photovoltaic cell (not shown) exposed to
the exterior of the case 101. For locations where radio frequency energy may be insufficient to provide power for the
transmitters, a combination of radio frequency and photovoltaic cell power can be utilized. In locations where insufficient
radio frequency energy is present in the location where the system is installed a user-installed radio frequency transmitter can be provided in the facility to power the transmitter. Also, mechanical generators which are powered by motion
of the wearer of the transmitter can be utilized for supplying power to the transmitter.
[0032] The transmitters 31 of the present invention are encoded by external magnetic pulse generators in a programming unit having a programming antenna to supply radio frequency energy to the loop antennae 136 provided in
the case 101 as previously described. They provide an inductance of about 100 nH. Power consumption is zero except
when programming the transmitter identity code. The added weight of the printed conductors and circuit space for the
programming antennae is negligible. The magnetic flux lines generated by the two matching loops 136 in the programmer are in opposite directions. Transistor switches Q3 and Q4 serve to drive the loops 136 from 5 volts to ground
through a resistor as shown. By way of example, the transistors Q3 and Q4 are driven at 20 Mhz with an on time of
15 nanoseconds and an off time of 35 nanoseconds with fly back voltage being limited to 5 volts. The switches Q3 and
Q4 provide a PD output on conductor 146 and a PCK output on conductor 147 to a multiplexer 151. The outputs PD
and PCK are a logic one when pulses are present at the correct strength and orientation on the conductors 146 and
147. Otherwise they are a logic zero. With this information a predetermined sequence can be utilized for programming
the transmitter 31.
[0033] The multiplexer 151 forms part of an identification and data register 152 consisting of integrated circuits U8,
U9, U10 and U14. These integrated circuits in combination form a 24-bit shift register which holds the transmitter
identification data as well as other data. Register 153 is initially programmed by the program circuit hereinbefore described. U8, U9 and U10 are shift registers 153 of a suitable type such as 74HC164. The multiplexer 151 is an integrated
circuit quad multiplexer as for example a 74HC157.
[0034] As each infrared packet is transmitted, the 24 bits of the register 152 are shifted once around a loop. Three
of the bits are selected at a time to control the timing of one of the eight infrared pulses of an infrared packet. During
message transmission by the transmitters as hereinafter described, each individual register 153 is an 8-bit circular
register controlled by the multiplexer 151.
[0035] The output SA3 of integrated circuit U10 is fed to integrated circuit U7 which serves as a multiplexer 156
which combines the programmed transmit interval and two high order ID bits supplied to it from SA3 with switch and
battery status information. The outputs SA1 and SA2 of the shift registers U8 and U9 as well as the output SA3M from
the multiplexer U7 are supplied to a packet timing circuit 158.
[0036] The multiplexer 156 is provided with inputs of three different frequencies, namely 3.5 KHz, 7 KHz and 14 KHz.
It is also supplied with a BOK input and a "data in" input which are provided for a purpose as hereinafter described.
The packet timing circuit 158 consists of integrated circuits U12 and U13 which are 74HC161 binary counters and an
integrated circuit U3B, a 74HC393 type 4-bit binary counter. The integrated circuits U12 and U13 control the timing of
the eight infrared pulses in the infrared packet. Each of the infrared pulses can be in one of the eight timed slots in the
packet. The three outputs SA1, SA2 and SA3M data packet register select the position for each pulse. The packet
timing circuit 158 encodes the eight successive 3-bit frames of data consisting of SA1, SA2 and SA3M into eight
successive pulses. Three bits of data are successively encoded as a single pulse position in one of eight time slots in
each of the eight data frames. Encoding is performed by loading the three bits of data SA1, SA2 and SA3M into
integrated circuit U12. As integrated circuit U12 is clocked, an output data pulse is created and the time slot encoded
by the 3-bit data preload. After all 24 bits have been coded and sent, the DONE output of U3B resets the fast clock
enable circuit 161 after which the transmitter 31 is returned to the low power interval counting mode as hereinafter
described.
[0037] The packet timing circuit 158 drives an output drive circuit 166. The drive circuit 166 includes Q1, Q2 and Q6
transistor drive circuitry of a conventional type in which the transistor Q6 speeds the turn off time for transistor Q2 to
thereby substantially reduce power consumption from the battery.
[0038] This transistor turn on circuitry serves to drive short duration high current pulses through the three infrared
emitters 127 which are connected in parallel.
[0039] In accordance with the present invention in controlling battery life, it is important to maximize the efficiency
of the conversion of battery power into infrared signals from the emitters 127. By properly selecting the infrared emitters,
they can be driven directly from the battery 71 and through the capacitive network 143 without a series limiting resistor.
At a 2.7 ampere current. the transistor switch circuitry comprised of the transistors Q1, Q2 and Q6, the bulk resistance
7
EP 1 229 672 B9 (W1B1)
of the emitter diodes and the effective series resistance of the battery 71 and the capacitors 43 limit the current to a
value which is safe for the emitters and switching the transistor. Consequently almost the entire battery voltage appears
across the parallel emitters resulting in optimum power conversion. By way of example, the average current and battery
requirements for transmission every two seconds is:
5
Avg. current = .000002 for low speed oscillator
+ .002 x .00079/2 for high speed logic
10
15
20
25
30
35
40
45
50
55
+ 2.7 x .000016/2 for infrared LED's
[0040] This makes it possible to achieve the battery life hereinbefore described for use in the transmitter 31 of the
present invention.
[0041] The program circuitry 144 consisting of the transistors Q3 and Q4 is activated by a very high level magnetic
field coupled to the printed circuit antenna connected to the bases of the transistors Q3 and Q4. They produce the
signal PD on line 146 which disables normal operation and enables the programming of the transmitter identification
register 152. The signal PCK on line 147 is then used to clock data on the PD line 146 into the transmitter. The programming signals PD and PCK are controlled by two independent high frequency magnetic pulse generators provided
in the special programming unit.
[0042] As shown in Figure 9, each transmitter 31 is provided with a slow clock 171. The slow clock 171 consists of
a 130 Hz resistive-capacitive oscillator which is provided by a transistor Q5 operating in conjunction with integrated
circuit U5 which is a 4060-type ripple counter that divides the 130 Hz frequency into selectable transmission intervals
and multiple repeat message rates. During the normal interval of transmission, the divided down outputs of integrated
circuit U5 are applied to the inputs of the integrated circuit U6 of the fast clock enable circuit 161 as shown in Figure
7. As shown the outputs from the integrated circuit U5 are 8 Hz and 2 Hz and two seconds and eight seconds respectively. The programmed transmit interval data controls whether the eight-second or the two-second interval clock generates the ICLOCK output. The ICLOCK output initiates the transmission of a message by the transmitter. When the
ICLOCK goes true as a result of integrated circuit U5 counting to the proper transmit interval, integrated circuit U2B
generates a CLKEN clock enable signal and its compliment CLKEN/ which controls the fast clock 172 and the mode
of the packet register 152. The slow clock 171 is designed to consume less than 2 microamperes of power using
standard CMOS circuits.
[0043] The fast clock 86 consists of an oscillator 176 which can be of a suitable form as for example an inexpensive
ceramic resonator resonating at 1 Mhz in connection with an integrated circuit U11, integrated circuit U4C the transistor
Q8 and the associated resistors and capacitors as shown in the drawings. The fast clock 172 operates as follows.
[0044] During normal interval transmission, the divided down outputs of U5 are applied to the inputs U6 of the fast
clock enable circuit 161. The programmed transmit interval data IV\, controls whether the 8 second or the 2 second
interval clock generates the ICLOCK output. ICLOCK initiates the transmission of a message. When ICLOCK goes
true as a result of U5 counting to the proper transmit interval, U2B generates a CLKEN clock enable signal and its
complement CLKEN\, which control the fast clock 172 and the mode of the packet register 152.
[0045] When the fast clock 172 is operating, the transmitter 31 uses much more power; therefore, it is enabled only
when needed. One of the four counted-down outputs from the slow clock 171 is selected by the fast clock enable circuit
161 consisting of integrated circuit U6 and flip-flop U2B to start up the fast clock. U11 and U4C are used to time the
sending of the infrared packet. Once the fast clock 86 is enabled, it waits one millisecond before sending the packet
to allow the ceramic resonator Y1 to stabilize. It then initiates the sending of the infrared packet. As soon as the packet
is sent, the fast clock 86 is turned off.
[0046] The fast clock 86 and logic use about 2 milliamperes; however, it only consumes power each time a packet
is sent for 790 microseconds out of every two seconds. The 1 Mhz output is divided by U11, a 4040 12-stage ripple
counter to generate a 250 KHz signal and a SEND signal. A NAND gate U4C inverts the 250 KHz signal to generate
an inverted 250 KHz signal. This oscillator 176 is normally off. These two 250 KHz signals are passed on by CLKEN.
[0047] In order to control battery power consumption, the fast clock 86 is only enabled when needed. For this purpose,
one of the four counted-down outputs from the slow clock 171 is selected by the fast clock to enable the circuit 161
consisting of integrated circuits U6 and U2B to start up the fast clock 86. Integrated circuits U11 and U4C in the fast
clock are used to time the sending of the infrared packet. Once the fast clock 86 is enabled, it waits 1 millisecond before
sending the infrared packet to allow the ceramic resonator 176 to stabilize. It then initiates the sending of the infrared
packet. As soon as the packet is sent, the fast clock 86 is turned off by the DONE output from H3B.
[0048] Although the fast clock and its logic use about 2 milliamperes of battery power, it only consumes that power
each time a packet is sent for 790 milliseconds out of every 2 seconds. The output from the fast clock 86 is divided by
8
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
integrated circuit U11 a 4040 binary ripple counter to generate a 250 KHz signal and a SEND signal. The NAND gate
U4C inverts the 250 KHz signal to generate a signal 250 KHz. This oscillator is normally off. These 250 KHz signals
are gated on by CLKEN.
[0049] In connection with the slow and fast clocks 171 and 86, power consumption is known to be proportionate to
clock oscillation rates. The relatively low rate of the slow clock consumes a very low power which is very desirable to
make it possible to minimize battery size for portability and battery life and for reduced operating costs of the system
of the present invention. Also to conserve battery power infrared pulses must be very narrow to control power consumption and therefore battery size. Since power consumption is also proportional to the width of an infrared pulse, a
high clock speed generating narrow pulses is desirable. However the pulses must be of an instantaneous power magnitude sufficient to modulate the infrared level well above the infrared noise of the room or area where the transmitter
is to be detected. The transmitter 31 of the present invention has a slow clock to determine transmit intervals. In between
transmissions the fast clock and emitters are disabled. When the slow clock times out, the fast clock and infrared
emitters are enabled long enough for the infrared packet to be sent after which they are again disabled to conserve
power.
[0050] During the transmission of an infrared packet much more power is used. The high power circuitry is in a low
power state except during transmission. During transmission the power is kept as low as possible using low power
parts and keeping the clocks as slow as possible. The duty cycle is very low so that the average power is very low.
[0051] The transmitter 31 of the present invention has two states of operation. One in which it is transmitting infrared
signals; and two when it is counting the time interval between infrared transmissions. When the infrared emitters 127
are conducting, the power consumption is high. They must conduct at least every two seconds to provide accurate
location information when they are moving as for example when carried by a person. Therefore, in the optimum transmitter, the emitters 127 must conduct for a very short time and in between transmissions, the alow clock power consumption must be negligible. As hereinafter explained, the transmitters 31 of the present invention transmit a packet
of infrared pulses at programmed intervals of either two or eight seconds, although other intervals may be selected as
hereinafter described. The two-second interval can be used for persons and items which move rapidly or frequently.
The eight-second interval can generally be used for inanimate items such as portable computers, files and other portable equipment which move slowly or infrequently. The data sent in a packet is encoded so that collisions (two transmitters sending at once), weak signals and noise can be detected. Transmit intervals longer than eight seconds generally do not extend battery life significantly so that in most applications of the present invention there is little value in
using longer transmit intervals.
[0052] The transmitter 31 of the present invention is provided with a battery check circuit 181 which is utilized to
monitor the battery 71 periodically to provide an advance warning that the battery will need replacement in the near
future. The battery check circuit 181 includes the transistor Q7 and a Zener diode D1 of a suitable type such as a
LM385 connected in the manner shown. This battery check circuit 181 tests the battery voltage during every transmitted
packet. If the battery voltage is at an acceptable level and a switch message is not being sent, a battery check message
BOK is sent along with the normal transmitter identification confirming the battery condition. When the battery is new
and the voltage is at 3 volts, the CLKEN is low and the 3-volt battery voltage appears between the emitter of Q5 and
the CLKEN signal. At this voltage the Zener diode conducts base current from transistor Q5 which saturates the collector
with a voltage providing a BOK signal indicating that the battery charge is good or satisfactory. When the battery is
discharged to the point wherein within one or two weeks the voltage will drop to a level that the range of transmission
will begin to be affected, the diode D1 no longer conducts enough current to saturate the transistor Q5 which changes
the BOK signal to a level indicating that the battery 71 needs replacement. This signal can be given in any suitable
manner as for example a visual signal, printed report, voice warning to the wearer, etc.
[0053] As hereinbefore explained, when two transmitters are within range of a receiver it is possible that the two
transmitters may transmit at the same time which means that the infrared packets for either or both may be lost to the
receiver. The probability of this occurring is the function of time between the time to transmit a packet and the number
of transmitters within range of a receiver. Assuming that transmitters transmit every two seconds, two transmitters will
transmit overlapping packets once in 3300 times with the time to transmit a packet being 288 microseconds. In the
present invention, repeated collisions between packets from two transmitters are prevented by causing random jitter
in the repetition rate of the slow clock 171. If the slow clock (packet interval) accuracy is 10 percent, there is an uncertainty of about 2,000 microseconds in the time of successive transmissions. This jitter very quickly resolves successive
collisions. If the actual clocks match 250 parts per million, two transmitters will not have more than one consecutive
collision. To achieve a controlled amount of jitter, the slow clock control in transmit interval does not use a crystal or
ceramic resonator for the time base. The relatively precise R-C time base creates jitter which prevents successive
collisions of respective infrared packets between multiple transmitters. Because the jitter in the array in the clock is
much greater than the packet transmission duration, two transmitters which transmit a packet at the same time are
very unlikely to transmit their next packets at the same time. Due to its high impedance and very slow oscillation rate,
the slow clock circuit requires very little power between transmissions.
9
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
[0054] Switch logic circuitry 186 provided in the transmitter 31 as shown in Figure 7 permits a transmitter to send a
message to the system 21. The switch logic circuitry includes integrated circuits U1A, U1B and U2A as well as integrated
circuit U3A, U4A and U4B to permit the transmitter 31 to send a message to the system. The integrated circuits U1A,
U1B and U2A remember which of the switches 87, 88 and 89 have been pressed. Integrated circuit U4A detects switch
operation and generates the B DOWN signal which resets the slow clock 171. While a switch is being pressed and for
250 milliseconds thereafter, no packets are sent. This allows for a combination of switches to be sensed even if they
are not actuated at the same time. Integrated circuit U4B detects any switch activation and generates the SSWITCH
signal. After this delay, the SSWITCH input to the fast clock enable circuit 161 selects a twice per second rate to send
packets until the packets have been sent with the switch information. The output of the switch latches 87, as and 89
are fed into the data packet via the integrated circuit U7.
[0055] UA1, U2A and U2B are integrated circuits which are connected to an integrated circuit U16 to provide data
and output to integrated circuit U7.
[0056] It should be appreciated in conjunction with the foregoing description that the meanings of the various combination of switch activations of the switches 87, 88 and 89 can be changed by the central logic programming. For
example, one such switch function could be assigned for testing the transmitter and receiver. Pressing the test button
causes all receivers which receive the signal to emit a short distinctive beep and flash an LED. This allows a user to
check the transmitter or receiver with no side effects.
[0057] Another function which could be assigned to the switches would be to indicate to the central logic of unit 22
of the system 21, that the wearer of the transmitter 31 desires privacy. By pressing the appropriate switches of the
switches 87, 88 and 89 would instigate a private mode for that transmitter and would cause the first receiver to receive
the signal to emit a short distinctive beep and flash an LED. That switch also could be used to designate to the central
logic unit 22 that the wearer wishes to clear a previously set status such as "privacy". Pressing the clear switch combination would cause the system to clear the private mode for that transmitter and cause a first receiver which receives
the signal to again emit a short distinctive beep and flash an LED. The switches 87, 88 and 89 also could be used to
designate an emergency situation to the central logic unit 22. For example, pressing two of the switches could cause
an "emergency one" or an "emergency two" alert to be transmitted to the receiver which would establish a special
status situation for room in which the emergency was first reported. The receiver detecting such an emergency code
could emit a distinctive continuous beep and an LED flash. The rooms emergency status condition could be cured by
pressing clear on any transmitter in the room where the emergency was generated.
[0058] Although in the present embodiment of the transmitter three momentary switches 87, 88 and 89 have been
shown, it should be understood that fewer or greater number of switches can be utilized if desired to offer the three bit
status code transmitted at the end of each packet. Pushing a switch can also be utilized to reset a transmit interval
counter and to thereafter initiate an immediate packet transmission. As can be seen from the foregoing, all switch
operations can result in immediate feedback from the nearest detecting receiver as for example by a distinctive beep
and an LED flash. While the button message assignment is arbitrary, assigning emergency codes to be initiated by
pushing multiple switches simultaneously reduces the chance that accidental emergency code transmissions can occur.
[0059] It should be appreciated that the momentary contact switches 87, 88 and 89 and the switch logic 186 can be
replaced with a conventional serial or parallel data communications port and that the transmitter 31 can be used to
send data from a portable or fixed personal computer hand held terminal or other data processing device. By adding
conventional receiver elements to the transmitter 31, the result is a transceiver which creates an infrared port that does
not require wire or fiber optic connections. With an infrared link, a portable device such as a personal computer that
can move throughout a facility while maintaining connection to other computer devices on a network. Because of the
very low power consumption of both the transmitter and the receiver circuitry, the infrared link would not materially
affect the power consumption of the portable device.
[0060] The system and apparatus 21 as hereinbefore explained also includes a magnetic programmer 33 which is
shown in Figure 3 and consists of a conventional pulse generator 187 which produces two sets of pulses, one to enable
and one to transmit actual data to a pair of transistors Q30 and Q40 and to two spaced apart antennae 188 of the same
type as the antennae in the portable transmitter 31 hereinbefore described. The pulse generator 187 is controlled from
a personal computer 189 which is provided with a software program for encoding the transmitters 31 magnetically
through radio frequencies as hereinafter described under the control of the personal computer 189.
[0061] The system and apparatus 21 also includes an infrared programmer 34 which is shown in Figure 4 and consists
of a transmitter 191 which can be of the type provided in transmitter 31 and is capable of emitting infrared signals which
can be utilized for programming the receivers 24. The transmitter 191 is under the control of a portable computer 192.
The portable computer 192 is provided with a software program which can be utilized for programming the receiver 24
as hereinafter described.
[0062] The operation and use of the optical data communication and location apparatus and system 21 of the present
invention in connection with the transmitters 31 hereinbefore described may now be briefly described in performing
the method of the present invention as follows. A data coding scheme is utilized to minimize battery power consumption
10
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
and is shown in Figures 10 and 11. As hereinbefore explained, the diodes 127 are utilized for transmitting packets of
infrared data pulses. The transmitter 31 includes the capability of generating a data code for these data pulses having
a finite number of time frames greater than one or expressed in other words at least two time frames which by way of
example have been identified as frames 0 through 7 in Figure 10. Each time frame is divided into a finite number of
data time slots greater than one, or in other words at least two time slots. Each frame consists of exactly one pulse
196 in one data time slot so that there are encoded n-bits of binary data in each frame of a data packet where 2n is
equal to the number of data time slots in a time frame. In such an arrangement battery power consumption is decreased
by a factor of n.
[0063] In the data coding scheme shown in Figure 10, the code types are shown for a representative message to
be transmitted. Thus, there are shown eight pulses, one in each of eight frames with each frame being shown with
nine time slots. From such a scheme it can be seen that infrared packets which are sent by the transmitter 21 use one
pulse to send three bits of information thereby keeping battery power consumption low. It should be appreciated that
the same scheme can be expanded or reduced so that one pulse can be encoded with more or less bits by increasing
or decreasing the quantity of time slots in each frame without affecting power consumption.
[0064] All infrared packets from all transmitters use the same energy because they always transmit exactly eight
pulses, independent of the data content. This makes battery life predictable and permits automatic correction of errors.
[0065] As shown in Figure 10, the first frame, FRAME 0 in a packet is reserved as a start flag. FRAME 0 always
contains a single infrared pulse 196 in the eighth data time slot (ninth time slot in the frame) counting from zero to
seven. The remaining seven frames of the eight frames each encode three bits of data with a pulse 191 in exactly one
of the nine time slots. FRAME 1 illustrates a pulse in data time slot 6 which encodes the three bit binary number (110)
shown underneath the frame. Below the binary code is the data assigned to each bit. In Figure 9 there is illustrated
the data time slot pulse position coding of the three bit data. Each pulse 196 denotes a "one" in that time slot in the frame.
[0066] It can be seen that the first time slot in each frame is used as a frame delimiter and never contains an infrared
pulse. In Figure 10, the delimiter time slot is labelled "x". No pulse is allowed to be present in this delimiter time slot.
This restriction guarantees that there will always be at least one empty time slot between two consecutive infrared
pulses. Seven frames encoding three bits provides a total of 21 bits of data. The 21 bits is comprised of a 16-bit
transmitter identity code, a 1-bit low battery or special function code, a 1-bit indicating the programmed transmit interval
for the transmitter, and a 3-bit code determined by the status of transmitter push button switches 87, 88 and 89 which
are activated. In connection with the description of the data code and scheme as shown in Figure 8, each time slot is
approximately four microseconds in length which gives a total transmit packet time of:
Eight Frame/Packet x 9 time slots/frame x 4 microseconds/time slot = 288 microseconds
35
40
45
50
55
[0067] Each of the infrared pulses is two microseconds wide. Ideally the infrared pulse is centered in the middle of
a four microsecond time slot. In connection with the present invention, it should be appreciated that narrower pulses
and higher clock speeds can speed transmission and that more frames or more time slots per frame increase the
encoded data.
[0068] The data coding scheme shown in Figures 10 and 11 provides a low overall power consumption. It equalizes
transmitter power consumption for all transmitters irrespective of the transmitted message. It permits automatic receiver
timing adjustment for transmitter timing errors. It makes possible reduced message collisions and it prevents repeated
collisions due to transmitters becoming synchronized. Automatic collision detection and automatic detection of missing
data allows automatic detection of weak signals, automatic infrared noise rejection, immunity to interference from
carrier based infrared signals and no interference to carrier based infrared communications.
[0069] As hereinbefore explained, the transmitter timing is derived from an inexpensive ceramic resonator time base
in each transmitter which has an accuracy of up to one percent. Thus in a worst case scenario the cumulative area of
error of 72 bit times could result in a pulse being detected one bit time too soon or with one bit time too late. Timing
drift compensation logic of the present invention continuously adjusts the receiver pulse sampling to keep pulses centered in bit time slots. Frequent phase adjustments during receipt of a packet allow the system to work even if there is
a large frequency of difference between the transmitter and the receiver thus permitting the receiver also to utilize an
inexpensive time base such as a ceramic resonator. In addition to providing identical power requirements for all transmitters, the data modulation technique or method herein disclosed incorporates self correcting timing. In Figures 12A,
12B and 12C there is disclosed a method of error detection and receiver clock timing drift compensation utilized in
connection with the present invention. As pointed out, there very well may be clock differences between the transmitter
and receiver clocks as a result of the lack of precision and drift of inexpensive time bases such as ceramic resonators
as utilized in the present invention; drift in related parts such as resistors and capacitors; and temperature differences
in clock components. As hereinbefore explained the data packets or pulses consist of eight frames, each of which is
divided into nine time slots of which eight can contain a data pulse. When each infrared pulse is received, the time slot
11
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
of the leading edge of the pulse is recorded by the main processor 51 of the receiver 24 and its clock is adjusted so
that the pulse is centered in the start flag time slot. Consequently, the clock in the receiver is adjusted so that the next
infrared pulse should be properly received in the center of its time slot.
[0070] Figures 12A, 12B and 12C show how each time slot is divided into three legal pulse position areas, "e" (early),
"-" (centered) and "1" (late), plus one illegal area "b" bridging two time slots. If any of the seven subsequent pulses is
received earlier than it should arrive as shown in Figure 12A, the receiver clock time is adjusted back by one position
so that the next pulse will be received in the center of the time slot and will be accepted. A pulse which is received in
the "late" position causes the receiver to adjust its time clock back one position and will be rejected as shown in Figure
12B. Similarly as shown in Figure 12B, if a pulse is found to be between or bridging two time slots, the packet is rejected.
Similarly if a pulse 191 is found in the frame delimiter time slot as shown in Figure 12C, the packet is rejected.
[0071] In summary, in Figure 12A there are shown time slots 6 and 7 of the third frame and time slots x and zero of
the following fourth frame. Below the time slots are the four phases of the time slot clock. The pulses 191 under the
phases of the time slot clock represent examples of received infrared pulses in the various phases of the time slot
clock. In Figure 12A, the first frame shows the data pulse 191 (value 1, 1, 0) arriving early during the "e" period so that
the clock is adjusted such that the next data pulse 191 (value 0, 0, 0) is centered in the frame (during the "-" period).
In Figure 12B, the first frame shows the indeterminate data pulse 191 (value between 1, 1, 0 and 1, 1, 1) arriving either
too late to be a "6" or too early to be a "7" (during the "1" period). This packet is rejected.
[0072] In the unlikely event of a collision of the transmissions between two or more transmitters, the overlapping of
packets are always detected as an error because it results in more than one pulse in at least one frame as illustrated
in Figure 12C.
[0073] Missing pulses in the received packet which are caused by weak signals are always detected as an error.
Noise which causes long IR pulses, short IR pulses or pulses with varying amplitudes is detected by the level detector
48 and is automatically rejected. Much of the ambient IR noise in buildings is related to the 50 to 60 Hertz power utilized
therein. Therefore, by having a packet duration much shorter than the power cycle, the likelihood of interference caused
by high levels of noise at one phase of the power cycle is low.
[0074] Because of their short duration, the short IR packets and very short IR pulses of this system and method of
the present invention tend to cause little or no interference with other systems utilizing an infrared carrier or line-ofsight or directional infrared. Infrared systems that utilize a carrier or are line-of-sight and directional energy will not
interfere with the short IR packets or the very short high energy IR pulses of the system and method of the present
invention.
[0075] If random infrared noise pulses are received after the first pulse, they are detected as noise and ignored. The
number of possible legal codes received is:
possible -- 264
(each of the remaining 64 time slots in the packet may or may not have a pulse)
legal -- 221
(each of the seven remaining infrared pulses may be received in one of eight legal positions)
35
40
45
50
55
[0076] In addition, pulses must occur near the middle of a time slot, and all pulses must be about the same energy.
Therefore, the probability of random pulses occurring in the proper time slots and at identical energy levels such that
they would be recognized as legal code is less than 1 in 243. In practice, random received infrared pulses will tend to
be the wrong pulse width and not of a constant energy level, resulting in rejection. Lastly, for infrared noise to be
accepted as data, there must be exactly one noise pulse, of the correct pulse width, in the center of a one time slot in
every frame. Therefore, the probability is vanishingly small of random noise pulses being accepted as a valid transmitter
message.
[0077] The operation and use of an optical data communication and location system 21 in a facility 201 [deletion(s)]
is shown in Figure 13. A facility by way of example can be a hospital which is provided with walls 202 that are impervious
to the optical energy being utilized for data communication and location as for example infrared. The walls 202 form a
plurality of spaced apart rooms 203 which are accessible through doors 204 opening into the rooms and giving access
to a hallway 206. Typically such a facility would also be provided with a ceiling (not shown) and a floor 207. The rooms
203 can be provided with desks 211 having telephones 212 thereon and chairs 213. As shown by the coded numbers
1 through 9, receivers 24 are indicated as being wall mounted, ceiling mounted and desk mounted. Transmitters 31
are indicated in various positions. Movable equipment 216 which is desired to be tracked can have transmitters 31
secured thereto. Such equipment can include portable medical carts, cardiac monitors, etc. Portable computers 217
having transmitters 31 secured thereto also can be tracked. Motion detectors 218 can be mounted in appropriate
locations. Key pads 219 for securing the premises can also be provided near appropriate doorways.
[0078] It should be appreciated that Figure 13 only shows a small number of the rooms and hallways which may be
provided in a facility and that typically the central logic unit 22 would be installed in the facility in a location which is
preferably near the geometric center of the receivers typically within 2,000 feet (609.6 m) of the most remote receiver.
12
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
50
55
Typically the receivers mounted in a facility should be mounted in such a manner so that they have an unobstructed
view of the rooms in which they are installed. If the receivers are associated with movable items which may later be
placed in front of the receivers, the receivers should be positioned so that they will remain unobstructed even if the
movable items are in fact moved. Typically the receiver should be mounted high enough in the room so that optimum
reception is obtained. For example mounting the receivers on walls from 7 feet to 9 feet 6 (2.13 to 2.90 m) above the
floor gives a receiver the best vantage point. The receiver should also be mounted on a surface so that it faces into
the room. It should not face the doorway into the room where it could detect people in the hallway as being in the room
when they are not. Thus, the receivers should face an interior wall. Typically, the receiver should be placed midway
along the wall because a single receiver of the present invention will generally provide good room coverage for a room
20' x 20' (6.1 m x 6.1 m) square office or a patient room. In hallways the receivers should be mounted approximately
25' (7.62) apart along the hall. Again they should not be placed so that they view directly into a doorway across the hall.
[0079] Upon installation of the apparatus and system 21 of the present invention, the transmitters 31 should be
encoded with the desired identification codes so that they can be tracked. These transmitters 31 can be programmed
one at a time by use of the magnetic programmer 33. The desired codes are supplied from the personal computer 189
to the pulse generator 187 which generates two sets of radio frequency pulses with one set providing enable pulses
and the other pet providing the actual data to the transistors Q30 and Q40 which are operated to supply the information
to the antennae 188 to be coupled into the corresponding antennae 136 of the transmitters 31. The transmitters 31
can thus be encoded one by one in a separate location or at the location 201.
[0080] Thereafter, in readying an installation for use, the receivers 24 are programmed. This is accomplished by
utilizing the infrared programmer 34. By way of example, infrared programmer 34 can be taken into a room which has
one of the transmitters 31 therein. Utilizing the information in the software program in the portable computer 192, the
transmitter 31 which can be coupled to an IO port of the computer 192 can be utilized for sending infrared pulses from
the transmitter 191 to the receiver 24 within the room to activate the receiver 24 and to provide the receiver 14 with
an identification code. The receiver 24 after receiving this identification code transmits this identification information
to the central logic unit 22 through by way of example hard wiring to place in the central logic unit 22 the location of
the receiver 24 sending in the identification code and the identification code for that receiver. Thereafter, the infrared
programmer 34 can be taken into the next room where there is a receiver and the same procedure carried out until all
of the receivers in the facility have been provided with identification codes which have been inserted into the central
logic unit 22.
[0081] As hereinbefore explained, the function of the infrared receivers 24 provided in the facility is to receive infrared
packets from nearby transmitters 31 and report the receipt of these packets to the central logic unit 22 of the identification
code, battery status and switch status of each of the transmitters from which infrared packets have been received. In
addition, the receivers control an LED and a beeper and may control the speaker for audio communications as hereinbefore explained.
[0082] In general as can be seen from Figure 13 the infrared detecting receivers 24 are located strategically within
rooms or other spaces so as to receive line-of-sight and reflected infrared signals from any transmitters 31 present in
the room. In a larger room such as an auditorium, multiple receivers 24 are installed to receive infrared signals from
the entire apace. In special applications where greater resolution of the locations inside a room is desired such as a
large office having work spaces separated by movable space dividers, receivers are installed in each work space. In
other special applications such as resolving the location of an individual object to within a few feet (approximately 1m),
receivers are installed with shades and/or of reduced sensitivity to restrict their range and viewing angle.
[0083] The receivers 24 store valid ID codes received from the transmitters 21 for transmission to the central logic
unit 22 of the system 21. As hereinbefore explained, each receiver 24 can have a piezo transducer, an LED, a speaker,
and an infrared motion detector. The piezo transducer functions as a tone generator to provide audible signaling tones.
The LED provides visual signaling. The speaker provides for one-way or two-way audio communication under the
control of the central logic unit 22. In security applications, the infrared motion detector 218 can be used in conjunction
with the current transmitted ID messages to determine whether unauthorized personnel are present at the receiver
location. If motion is detected and there are no allowed transmitter ID's present an alarm is sounded. Similarly, if
unauthorized ID's are present, an alarm is sounded. Access control can be achieved by a restricted range receiver
controlling the door lock or a key pad 219. The doors would only allow access if the person trying to enter had an
authorized transmitter and the correct lock combination or key.
[0084] From the teaching of the present invention, the transmitters 31, the receivers 24 as well as the central processing unit 22, can be readily constructed to detect the infrared signals and to convert them to electrical signals which can
be read by digital logic. The main processor 51 of the receiver 24 is based on a microcomputer which is utilized to
process infrared packets received from nearby transmitters to keep track of timeouts and process messages received
from the central logic unit and process commands received from the central logic unit. The main processor also includes
a clock and a set of the memory data registers. Each receiver has a unique 16-bit receiver identification number stored
in a non-volatile memory register. The 16-bit identification provides for over 65,000 receivers. A larger receiver iden-
13
EP 1 229 672 B9 (W1B1)
5
10
15
20
25
30
35
40
45
tification number would provide for more receivers if that is desired.
[0085] The central logic unit can send commands to specific receivers or can send a general query to all receivers
simultaneously to locate a specific transmitter. If a telephone call is being received for a person when there are several
persons in the room having a telephone therein, the receiver 24 can be used to communicate audibly which of the
persons in the room is to pick up the telephone in that room.
[0086] The general operation of the apparatus system and method is very similar to that disclosed in U.S. Patent
No. 5062151. In placing the system in use, the identification codes of the receivers 24 and the transmitters 31 are
encoded into the central logic unit with the receivers being identified with respect to locations in a facility as for example
the facility 201 shown in Figure 13 in the manner hereinbefore described. Assuming that the apparatus, system and
method is to be utilized for locating personnel in a facility as for example a hospital for locating nurses and physicians,
the transmitters with their identification codes would be assigned to the personnel with each physician or nurse or other
person desired to keep track of in the facility being assigned a transmitter. As described in U.S. Patent No. 5,062,151
the apparatus in the system is able to carefully and accurately monitor the location of personnel in the facility by
ascertaining which receiver is physically closest to a transmitter. The transmitters carried by the personnel are capable
of sending messages of various types. The receivers 24 as shown in Figure 11 can be monitored so that they can
monitor individual rooms, locations in rooms hallways and the like so that the apparatus and system is capable of
continuously monitoring the location of personnel. Personnel in a facility may be given a message over the transmitter
to use the closest telephone 212 as shown in Figure 13.
[0087] When the system apparatus is utilized for monitoring the location of things which may move slowly or infrequently, the apparatus, system and method of the present invention also can be utilized in such applications.
[0088] The apparatus, system and method of the present invention is one in which a large number of receivers and
transmitters can be accommodated. A data coding method has been utilized which makes this possible and also makes
it possible to make the transmitters very light and portable with the capability of utilizing power supplies which utilize
ambient radio frequency or ambient light energy. When necessary batteries can be used. The battery can be relatively
small and lightweight which in most applications can last as long as a year or several years. Battery life is periodically
monitored in the apparatus, system and method and gives a warning when the battery should be replaced. The system
is reliable and immune to noise. Data collisions are minimized. False data is not recorded. A plurality of light emitting
diodes are provided for emitting sufficient power to ensure that the transmitter can be readily located by the closest
receiver. The receivers have the capability of determining the power level of the transmitted infrared pulses from two
to more transmitters and are capable of discriminating against the more remote transmitter having a lower power level
thereby minimizing interference between transmitters. The receivers are programmed so that information is transmitted
only if new or changed data is received by the receivers.
[0089] The apparatus and system 21 of the present invention can be utilized with a portable data link as shown in
Figure 14. As shown therein, the portable data link can be provided in a facility 201 of the present invention by providing
in one of the rooms 203 a transmitter 31 and a receiver 24, both in a stationary position in the room as for example on
the wall of the room which are coupled to the central logic unit 22. The transmitter 31 and the receiver 24 establish
communication with a portable data link in the room in the form of a computer system 231 which includes a portable
computer 232 of a conventional type which has secured to the input and output ports thereof a transmitter 31 and a
receiver 24. Thus, the computer system 231, as a portable data link, can establish communication between the transmitter 31 and the receiver 24 mounted in the room 203. In this way, two-way communication can be established between
the person utilizing the computer system 231 in conjunction with the apparatus and system which is installed in the
facility 201 through the central logic unit 22.
[0090] From the foregoing, it can be seen that there has been a provided optical data communication and location
apparatus, system and method which provides continuous real time information on the location of people, equipment
files and other mobile objects in a facility which does not require line-of-sight transmission.
Claims
50
1.
An optical data communication apparatus (21) for a facility (201) including a receiver (24) located in a location (26)
of the facility and a plurality of portable transmitters (31) carried by a corresponding plurality of individuals, characterized by a motion detector (8) located in the location, a plurality of optical wireless data links (77) that facilitate
communication between the receiver and the plurality of transmitters, each transmitter having a unique identification code (82), and means (51) for actuating an alarm when an individual is detected in the location by the motion
detector without a portable transmitter having an identification code indicating that the individual is permitted access
to the location.
2.
The apparatus (21) of claim 1 wherein the actuating means (51) includes a processor coupled to the receiver (24),
55
14
EP 1 229 672 B9 (W1B1)
the motion detector (8) and the alarm.
3.
The apparatus (21) of either of claims 1 or 2 wherein the motion detector (8) is an infrared motion detector.
5
4.
The apparatus (21) of any of the previous claims wherein the actuating means (51) actuates the alarm when the
motion detector (8) detects an individual in the location and the receiver (24) receives an identification code (82)
that is not among a plurality of identification codes associated with portable transmitters (31) issued to individuals
authorized to have access to the location.
10
5.
The apparatus (21) of claim 4 wherein the plurality of identification codes are stored in a memory coupled to the
actuating means (51), the actuating means comparing the received identification code to the stored plurality of
identification codes to determine whether the individual carrying the portable transmitter (31) transmitting the identification code is authorized to have access to the location.
15
6.
The apparatus (21) of any of claims 1-3 wherein the actuating means (51) actuates the alarm when the motion
detector (8) detects an individual in the location, but the receiver (24) fails to receive an identification code (82)
from a portable transmitter (31).
7.
The apparatus (21) of any of the previous claims further characterized in that each of the plurality of portable
transmitters (31) includes a power supply (77).
8.
The apparatus (21) of any of the previous claims further characterized in that each of the plurality of portable
transmitters (31) includes means (66, 82, 73, 78, 86, 79, 76) for transmitting data packets over the optical wireless
data links (77) to the receiver (24).
9.
The apparatus (21) of claim 1 wherein a plurality of locations (26) are provided in the facility (201) with a receiver
(24) in each location, said facility including a central logic unit (22) and communication interface means (36, 53)
for establishing communication between the receivers and the central logic unit.
20
25
30
10. The apparatus (21) of claims 1-8 and 9 together with an access keypad (9) at said location (26) which must be
actuated to gain access to said at least one location, access to said at least one location being given if a code
entered on the access keypad and the identification code being transmitted by the transmitter (31) match one
another indicating that the individual with the transmitter is to have access to said location.
35
11. The apparatus (21) of claim 8 wherein each of the plurality of portable transmitter (31) includes a battery (71) and
wherein the data packet includes battery replacement data (166).
12. The apparatus (21) of claims 8 and 11 further including a data packet register means (73) for encoding transmitter
identification data into the data packets.
40
13. The apparatus (21) of claims 8, 11 and 12 wherein said receiver (24) is immune to noise in the data packets from
carrier modulated systems and carrier based systems.
45
14. The apparatus (21) of any of the previous claims wherein each of the plurality of portable transmitters (31) at least
transmits the unique identification code (B2) to the receiver (24) when in the location (26).
15. The apparatus (21) of any of claims 1-8 and 9-14 wherein each of said plurality of transmitters (31) has a plurality
of manually actuatable switches (87, 88, 89), said switches being coded to provide various types of status information.
50
Patentansprüche
1.
55
Ein optischer Datenkommunikationsapparat (21) für eine Einrichtung (201), welche einen Empfänger (24), der an
einen Standort (26) der Einrichtung angeordnet ist, sowie eine Vielzahl tragbarer Sender (31), welche von einer
entsprechenden Vielzahl Personen getragen werden, einschließt, gekennzeichnet durch einen Bewegungsdetektor (8), welcher an dem Standort angeordnet ist, eine Vielzahl optischer drahtloser Datenverbindungen (77),
welche Kommunikation zwischen dem Empfänger und der Vielzahl Sender ermöglicht, wobei jeder Sender einen
15
EP 1 229 672 B9 (W1B1)
einmaligen Identifikationscode (62) sowie Mittel für das Betätigen eines Alarms aufweist, wenn eine Person an
den Standort durch den Bewegungsdetektor festgestellt wird, welche nicht einen tragbaren Sender mit einem
Identifikationscode aufweist, der anzeigt, dass der Person Zugang zu dem Standort gewährt wurde.
5
2.
Der Apparat (21) gemäß Anspruch 1, wobei das Betätigungsmittel (51) einen Prozessor einschließt, der mit dem
Empfänger (24), dem Bewegungsdetektor (8) und dem Alarm verbunden ist.
3.
Der Apparat (21) gemäß einem der Ansprüche 1 oder 2, wobei der Bewegungsdetektor (8) ein Infrarotbewegungsdetektor ist.
4.
Der Apparat (21) gemäß irgendeinem der vorangehenden Ansprüche, wobei das Betätigungsmittel (51) den Alarm
betätigt, wenn der Bewegungsdetektor (8) eine Person an dem Standort entdeckt und der Empfänger (24) einen
Identifikationscode (82) empfängt, der nicht unter einer Vielzahl von Identifikationscode enthalten ist, die tragbaren
Sendern (31) zugeordnet sind, welche an Personen, welche befugt sind, Zugang zu dem Standort zu haben,
ausgegeben worden sind.
5.
Der Apparat (21) gemäß Anspruch 4, wobei die Vielzahl Identifikationscodes in einem Speicher, der mit dem Betätigungsmittel (51) verbunden ist, gespeichert werden, wobei das Betätigungsmittel den empfangenen Identifikationscode mit der gespeicherten Vielzahl Identifikationscodes vergleicht, um festzustellen, ob die Person, die den
tragbaren Sender (31) trägt, der den Identifikationscode sendet, befugt ist, Zugang zu dem Standort zu haben.
6.
Der Apparat (21) nach irgendeinem der Ansprüche 1-3, wobei das Betätigungsmittel (51) den Alarm betätigt, wenn
der Bewegungsdetektor (8) eine Person an dem Standort entdeckt, der Empfänger (24) aber nicht einen Identifikationscode (82) von einem tragbaren Sender (31) empfängt.
7.
Der Apparat (21) gemäß irgendeinem der vorangehenden Ansprüche, der weiter dadurch gekennzeichnet ist,
dass jeder der Vielzahl tragbarer Sender (31) eine Stromversorgung (77) einschließt.
8.
Der Apparat (21) gemäß irgendeinem der vorangehenden Ansprüche, weiter dadurch gekennzeichnet, dass
jeder der Vielzahl tragbarer Sender (31) Mittel (66, 82, 73, 78, 86, 79, 76) für die Übertragung von Datenpaketen
über optische drahtlose Datenverbindungen (77) zu dem Empfänger (24) einschließt.
9.
Der Apparat (21) gemäß Anspruch 1, wobei eine Vielzahl von Standorten (26) in der Einrichtung (21) mit einem
Empfänger (24) an jedem Standort vorgesehen ist, wobei die besagte Einrichtung eine zentrale logische Einheit
(22) und Kommunikationsschnittstellenmittel (36, 53) für das Aufbauen einer Kommunikation zwischen den Empfängern und der zentralen logischen Einheit einschließt.
10
15
20
25
30
35
40
45
10. Der Apparat (21) gemäß Ansprüchen 1-8 und 9 zusammen mit einer Zugangstastatur (9) an besagtem Standort
(26), welche betätigt werden muss, um Zugang zu besagtem, zumindest einen Standort zu erlangen, wobei Zugang
zu besagtem zumindest einem Standort gewährt wird, wenn ein Code, der auf der Zugangstastatur eingegeben
wird mit dem von dem Sender (31) übertragenen Identifikationscode übereinstimmt, um anzugeben, dass der
Person mit dem Sender Zugang zu besagtem Standort gewährt werden soll.
11. Der Apparat (21) gemäß Anspruch 8, wobei jeder der Vielzahl tragbarer Sender (31) eine Batterie (71) einschließt,
und wobei das Datenpaket Daten (166) über den Ersatz der Batterie einschließt.
12. Der Apparat (21) gemäß Ansprüche 8 und 11, der weiterhin ein Datenpaketregistermittel (73) für das Codieren
von Senderidentifikationsdaten in den Datenpaketen einschließt.
50
55
13. Der Apparat (21) gemäß Ansprüche 8, 11 und 12, wobei der besagte Empfänger (24) immun gegen Störung in
den Datenpaketen von trägermodulierten System und trägerbasierten System ist.
14. Der Apparat (21) gemäß irgendeinem der vorangehenden Ansprüche, wobei jeder der Vielzahl tragbarer Sender
(31) zumindest den einmaligen Identifikationscode (82) zu dem Empfänger (24) überträgt, wenn er an dem Standort
(26) ist.
15. Der Apparat (21) gemäß irgendeinem der Ansprüche 1-8 und 9-14, wobei jeder der besagten Vielzahl von Sendern
(31) eine Vielzahl manuell betätigbarer Schalter (87, 88, 89) aufweist, wobei besagte Schalter codiert werden, um
16
EP 1 229 672 B9 (W1B1)
verschiedene Typen von Statusinformationen vorzusehen.
Revendications
5
1.
Appareil de communication de données optiques (21) pour une installation (201) qui inclut un récepteur (24) qui
est localisé au niveau d'une localisation (26) de l'installation et une pluralité d'émetteurs portables (31) qui sont
portés par une pluralité correspondante d'individus, caractérisé par un détecteur de déplacement (8) qui est
localisé au niveau de la localisation, par une pluralité de liaisons de données sans fil optiques (77) qui facilitent
une communication entre le récepteur et la pluralité d'émetteurs, chaque émetteur disposant d'un code d'identification unique (82), et par un moyen (51) pour actionner une alarme lorsqu'un individu est détecté au niveau de la
localisation par le détecteur de déplacement sans qu'un émetteur portable dispose d'un code d'identification indiquant que l'individu est autorisé à accéder à la localisation.
2.
Appareil (21) selon la revendication 1, dans lequel le moyen d'actionnement (51) inclut un processeur qui est
couplé au récepteur (24), au détecteur de déplacement (8) et à l'alarme.
3.
Appareil (21) selon la revendication 1 ou 2, dans lequel le détecteur de déplacement (8) est un détecteur de
déplacement à infrarouges.
4.
Appareil (21) selon l'une quelconque des revendications précédentes, dans lequel le moyen d'actionnement (51)
actionne l'alarme lorsque le détecteur de déplacement (8) détecte un individu au niveau de la localisation et que
le récepteur (24) reçoit un code d'identification (82) qui n'est pas parmi une pluralité de codes d'identification qui
sont associés à des émetteurs portables (31) qui sont délivrés à des individus autorisés à avoir accès à la localisation.
5.
Appareil (21) selon la revendication 4, dans lequel les codes de la pluralité de codes d'identification sont stockés
dans une mémoire qui est couplée au moyen d'actionnement (51), le moyen d'actionnement comparant le code
d'identification reçu à la pluralité stockée de codes d'identification pour déterminer si oui ou non l'individu porteur
de l'émetteur portable (31) qui émet le code d'identification est autorisé à avoir accès à la localisation.
6.
Appareil (21) selon l'une quelconque des revendications 1 à 3, dans lequel le moyen d'actionnement (51) actionne
l'alarme lorsque le détecteur de déplacement (8) détecte un individu au niveau de la localisation mais que le
récepteur (24) échoue à recevoir un code d'identification (82) depuis un émetteur portable (31).
7.
Appareil (21) selon l'une quelconque des revendications précédentes, caractérisé en outre en ce que chacun
de la pluralité d'émetteurs portables (31) inclut une alimentation (77).
8.
Appareil (21) selon l'une quelconque des revendications précédentes, caractérisé en outre en ce que chacun
de la pluralité d'émetteurs portables (31) inclut un moyen (66, 82, 73, 78, 86, 79, 76) pour émettre des paquets
de données sur les liaisons de données sans fil optiques (77) jusqu'au récepteur (24).
9.
Appareil (21) selon la revendication 1, dans lequel une pluralité de localisations (26) sont prévues dans l'installation
(201) moyennant un récepteur (24) au niveau de chaque localisation, ladite installation incluant une unité logique
centrale (22) et un moyen d'interface de communication (36, 53) pour établir une communication entre les récepteurs et l'unité logique centrale.
10
15
20
25
30
35
40
45
50
55
10. Appareil (21) selon les revendications 1 à 8 et 9 en association avec un mini-clavier d'accès (9) au niveau de ladite
localisation (26), qui doit être actionné pour obtenir un accès à ladite au moins une localisation, un accès à ladite
au moins une localisation étant octroyé si un code qui est entré sur le mini-clavier d'accès et le code d'identification
qui est émis par l'émetteur (31) se correspondent l'un l'autre, ce qui indique que l'individu muni de l'émetteur doit
avoir accès à ladite localisation.
11. Appareil (21) selon la revendication 8, dans lequel chacun de la pluralité d'émetteurs portables (31) inclut un
accumulateur (71) et dans lequel le paquet de données inclut des données de remplacement d'accumulateur (166).
12. Appareil (21) selon les revendications 8 et 11, incluant en outre un moyen d'enregistrement de paquet de données
(73) pour coder des données d'identification d'émetteur selon des paquets de données.
17
EP 1 229 672 B9 (W1B1)
13. Appareil (21) selon les revendications 8, 11 et 12, dans lequel ledit récepteur (24) est immunisé vis-à-vis du bruit
dans les paquets de données en provenance de systèmes modulés en porteuse et de systèmes basés sur porteuse.
5
10
14. Appareil (21) selon l'une quelconque des revendications précédentes, dans lequel chacun de ladite pluralité
d'émetteurs portables (31) émet au moins le code d'identification unique (82) sur le récepteur (24) lorsqu'il est au
niveau de la localisation (26).
15. Appareil (21) selon l'une quelconque des revendications 1 à 8 et 9 à 14, dans lequel chacun de ladite pluralité
d'émetteurs (31) comporte une pluralité de commutateurs actionnables manuellement (87, 88, 89), lesdits commutateurs étant codés pour fournir divers types d'information d'état.
15
20
25
30
35
40
45
50
55
18
EP 1 229 672 B9 (W1B1)
19
EP 1 229 672 B9 (W1B1)
20
EP 1 229 672 B9 (W1B1)
21
EP 1 229 672 B9 (W1B1)
22
EP 1 229 672 B9 (W1B1)
23
EP 1 229 672 B9 (W1B1)
24
EP 1 229 672 B9 (W1B1)
25
Download PDF
Similar pages