datasheet for LM238-320WXN by Landmark Technology

datasheet for LM238-320WXN by Landmark Technology
LM238-320WXN - 32" High Bright
LCD Module for Digital Signage
The LM238-320WXN is a 31.5" high bright LCD module specifically designed for digital signage applications. The
module contains an LG LC320WXN LCD with a Landmark very high brightness (VHB) backlight and a set of
inverters to run the VHB backlight. At the full brightness setting, the screen luminance reaches 1,400 nits - three
times the brightness of standard 32" LCD TVs. It also has an extremely high contrast ratio of 1,100:1.
The LM238 module has 1,366 x 768 native resolution. At 1,400 nits brightness, the image on the screen matches the
superb quality of traditional advertising signs that use light boxes behind color transparencies. In addition, the color
of the white is balanced closely to that of a traditional backlit sign.
The inverters that operate the LM238-320WXN VHB backlight require 24V DC input. The 24V power supply should
be able to deliver a minumn of 7 Amperes in order to run the LCD at the maximum brightness.
Electrical & Optical Characteristics (notes 1, 2, 3)
Typical Value
LCD Screen Luminance
LCD displays the brightest White
Luminance Variation
±15% or better
Backlight Power Consumption
LCD Luminance Dimming Ratio
With BI520 / BI522 inverter set
Typical LCD Contrast Ratio
White vs. Black (measured in the
dark along the normal direction)
Typical Viewing Angles
3:00 direction
9:00 direction
6:00 direction
12:00 direction
LCD Screen Chromaticity (x, y)
(0.318, 0.354)
(0.635, 0.343)
(0.282, 0.620)
(0.142, 0.069)
LCD Module Weight
Note 3
Excluding inverter losses
Contrast ratio ³ 10
Contrast ratio ³ 10
Contrast ratio ³ 10
Contrast ratio ³ 10
Measured at the normal direction
Measured at the normal direction
Measured at the normal direction
Measured at the normal direction
K Grams
With Inverters and the cover
Note 1: Please refer to LG LC320WXN LCD Specification for LCD electrical specifications & general precautions.
Note 2: All data is measured at 25º C ± 2ºC ambient temperature.
Note 3: Screen luminance is measured at 5 points as shown in the LG LC320WXN LCD data sheet. The luminance variation is
the percent deviation of the maximun and minimun values neasured versus the average luminance value of the 5 points.
Landmark Technology 172 Component Drive San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954
Landmark Technology
Luminance, Contrast Ratio, Chromaticity, & Color Shifts
The luminance, contrast ratio (CR), and the chromaticity values (x, y) in the table are all measured at the on-axis viewing
direction. As the viewing direction shifts to off-axis angles, both the luminance and contrast ratio drops. However, the
chromaticity (x, y) values of the R, G, B primary colors do not change at off axis angles since this is a normally black
wide viewing angle LCD module.
The LM238-320WXN LCD module has a high contrast ratio (CR) of 1100:1. This is the inherent CR, which is the
luminance ratio between the “White” and the “Black” states measured in a dark room. Under ambient lighting,
particularly in bright outdoor environments, the CR value of the display drops significantly due to the reflection and
glare caused by strong ambient illumination at the front surface of the display.
Inverters to Drive the LM238-320WXN VHB Backlight
The LM238-320WXN high bright LCD module has
a VHB backlight with 24 cold cathode fluorescent
lamps (CCFLs). The lamps are electrically
connected into three groups. Each group has 8
lamps connected as shown in the following figure.
The lamps are connected at one side to two JST
4-pin connectors. The other side of the lamps are
tied together into a lamp common connection. A
JST 2-pin connector is used to provide redundant
connections for the lamp common.
The entire LM238-320WXN VHB backlight has 6
JST 4-pin connectors for 24 lamps and 3 JST 2-pin
connectors for the 3 lamp commons. The part
numbers of the connectors and their mating
connectors are listed in the figure below.
The VHB backlight is operated with two
Landmark inverters in a master and slave
configuration. The master inverter BI520A
operates two groups of lamps (16 lamps) and has
the dimming and the backlight On/Off control.
The VHB backlight has 24 lamps
connected in 3 groups. Each
group has 8 lamps as shown here
Lamp Connectors - 6 pcs
Contact Pins:
JST SBH-001T-P0.5
Mating Connector:
JST SM04(4.0)B-BHS-1-TB
Lamp Common Connectors - 3 pcs
Contact Pins:
JST SBHS-002T-P0.5
Mating Connector:
JST 4 - pin
BH Connector
JST 4 - pin
BH Connector
JST 2 - Pin BHS
Lamp Common
Landmark Technology 172 Component Drive San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954
Landmark Technology
The slave inverter BI522A operates one group of 8
lamps. It receives a signal from the BI520A master
inverter for dimming and On/Off controls. For
interconnections of the inverters, please refer to the
BI520A and BI522A data sheets.
The long CCFLs in this 32" LCD module require a
starting voltage greater than 2,000 Vrms. This high
voltage is extremely dangerous. To protect the
users, the high voltage areas of the inverters are
fully shielded with a metal cover. If any service
work is performed that requires removal of the
metal cover, please do not touch any exposed
metal parts that may carry the high voltage. Please
refer to the BI520A and BI522A data sheets for the
high voltage locations on the inverter boards.
The inverters run on 24 V DC input. At the full LCD
screen luminance setting, the current input to the
inverters is about 7 Amperes. At this level, the
LCD screen luminance (brightness) will be at 1,400
nits. With proper dimming signal input, the
brightness can be adjusted down to below 100 nits.
Correspondingly, the lamp current and the input
current to the inverter reduce in proportion to the
Backlight Life
The LM238-320WXN VHB backlight uses CCFLs with 50,000 hours of rated half brightness life. The half
brightness life is the number of operating hours before the CCFL surface luminance drops down to 50% of its
initial value. The half brightness life is specified at a given lamp current (typically at 5 mA). Driving the CCFLs
at a lower lamp current increases the half brightness life. Conversely, over driving the CCFLs to a higher current
reduces the half brightness life.
At the rated LCD screen luminance of 1,400 nits, the CCFLs in the backlight are driven at a lamp current slightly
higher than the rated value. Therefore, the half brightness life of the lamp should be slightly lower than 50,000
hours. In addition, the brightness of a backlight (and so the LCD screen brightness) decays slightly faster than that
of a CCFL due to the aging of other materials in the backlight. Even with these consideration, the actual operating
half brightness lifetime of the backlight in this LCD module is expected to reach 50,000 hours and beyond, in
particular, if the LCD screen luminance is adjusted (or dimmed) down during night time. For detailed descriptions
on backlight life issues and actual test data on Landmark Technology backlights, please refer to Technical Note
TK801 on Landmark website.
Thermal Management
The total backlight power consumption of the LM238-320WXN LCD module including the inverter losses is about
165 Watts at 1,400 nits screen brightness. This is about 1.5 time the backlight power of the original LG LC320WXN
LCD at the maximum screen brightness of 500 nits. As a result, the LM238 LCD module temperature will be higher
by about 5 - 6ºC than the temperature of the original LG LCD running at 500 nits.
The exact increase in temperature depends on the installation of the LCD module in the equipment. In open air, the
LCD module can be operated at 1,500 nits without any cooling. However, when it is installed in a case, some type
of cooling measure should be implemented to ensure that the LCD temperature stays within the 0 to 50ºC range
specified in the data sheet of the LG LC320WXN.
Landmark Technology 172 Component Drive San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954
Landmark Technology
For outdoor display applications where the LCD may be subject to direct sunlight exposure, the major source of heat
usually comes from sunlight exposure. LCDs are suitable for outdoor applications because they have a low reflective,
black front surface. However, a black surface is a good solar energy absorber. For example, if strong sunlight shines
on the LM238-320WXN LCD module at a perpendicular direction, the LCD module can absorb up to 300 Watts of
solar power. This is nearly twice as much as the maximum power consumption of the VHB backlight with the inverter
loss. As a result, the LCD temperature can rise very quickly beyond its maximum tolerance level.
It is recommended that the LCD screen temperature be measured at full brightness, in the equipment, under actual
operating environments. The cooling measure should then be designed accordingly. Please ensure that the specified
maximum LCD temperature is not exceeded.
Landmark Technology Inc. reserves the right to make changes to this document and the product which it describes without notice. In
addition, Landmark Technology Inc. shall not be liable for technical or editorial errors or omissions made herein; nor for incidental or
consequential damages resulting from the furnishing, performance, and use of this product.
This product shall not be used for or in connection with equipment that requires an extremely high level of reliability, such as military
and aerospace applications, telecommunication equipment, nuclear power control equipment and medical or other life support
equipment. Landmark Technology Inc. takes no responsibility for damage caused by improper use of this product which does not meet
the conditions for use specified in this specification sheet.
Landmark Technology 172 Component Drive San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954
Landmark Technology
LM238-320WXN Mechanical Dimensions
64 ±1
760 ±1
Active Area
697.7 x 392.3
Bazel Opening
703.8 x 398.4
450 ±1
LCD Center
8 mounting holes, M4 tapped
Torque = 4 - 5 Kg-cm
22.0, 4x
190 ±0.5, 2x
190 ±0.5, 2x
166 ±0.5, 2x
LCD Center
166 ±0.5, 2x
LCD Connector
LCD Topside
All dimensions are in mm
Landmark Technology 172 Component Drive San Jose, CA 95131 (408) 434-9302 Fax: (408) 434-0954
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF