US 20070263 524A1 (19) United States (12) Patent Application Publication (10) Pub. No.: US 2007/0263524 A1 (43) Pub. Date: Thompson et al. (54) OPTICAL MEDIA FORMATS AND NOV. 15, 2007 Related US. Application Data METHODS OF MAKING SAME (75) Inventors: Robert E. Thompson, Boca Raton, FL (US); Arthur R. Leblanc III, Kennebunk, ME (US); Edward P. Lindholm, Brookline, MA (US); Louis Cincotta, Andover, MA (US); Joseph Paulus, Portland, ME (US) (60) Provisional application No. 60/711,616, ?led on Aug. 26, 2005. Publication Classi?cation (51) Int. Cl. G11B 7/24 (52) US. Cl. ........................................................ ..369/275.1 (2006.01) Correspondence Address: MORRIS MANNING MARTIN LLP 3343 PEACHTREE ROAD, NE 1600 ATLANTA FINANCIAL CENTER ATLANTA, GA 30326 (US) (57) ABSTRACT Apparatuses, products, and devices consistent With the invention include optically readable media With at least one substrate, at least one encoded information region and/or region for receiving and/or recording encoded information, (73) Assignee: Flexplay Technologies, Inc.,Atlanta, GA and at least one mechanism, chemical, agent, and/ or process for limiting the time period that at least a portion of the at (21) Appl. No.: 11/467,685 (22) Filed: Aug. 28, 2006 least one encoded information region and/or region for receiving and/or recording encoded information can be read and/or accessed by an optical beam and/or reader capable of reading the encoded information. 45 40 5 ZS Patent Application Publication Nov. 15, 2007 Sheet 1 0f 15 US 2007/0263524 Al \0 <1 3 (A ‘5; < u‘ g/. 5 m / \1 Patent Application Publication Nov. 15, 2007 Sheet 2 0f 15 US 2007/0263524 Al FIG.2 Patent Application Publication Nov. 15, 2007 Sheet 3 0f 15 ‘2- US 2007/0263524 A1 . O, Q F185 Patent Application Publication Nov. 15, 2007 Sheet 4 0f 15 3 US 2007/0263524 A1 5 \ . / 1 o // d“ J H m ‘w 64 <31 qr)J, Patent Application Publication Nov. 15, 2007 Sheet 5 0f 15 US 2007/0263524 A1 156 Fig, 5 150 HO Patent Application Publication Nov. 15, 2007 Sheet 6 0f 15 Q05 210 Q15 200 m0 1w US 2007/0263524 A1 4 \/ A, HQ. (0 Patent Application Publication Nov. 15, 2007 Sheet 7 0f 15 US 2007/0263524 A1 ‘é C) d) Patent Application Publication Nov. 15, 2007 Sheet 8 0f 15 US 2007/0263524 A1 10 35 2 FIG. ‘950 Patent Application Publication Nov. 15, 2007 Sheet 9 0f 15 i v 4 .495 MMzw ‘i’°\\ v 405"; ‘415 US 2007/0263524 A1 ‘ "f" k0 415/ / W 4/5 Patent Application Publication Nov. 15, 2007 Sheet 10 0f 15 FIG. 1” US 2007/0263524 A1 Patent Application Publication Nov. 15, 2007 Sheet 12 0f 15 500 SIB HQ. I7 US 2007/0263524 A1 555' Patent Application Publication Nov. 15, 2007 Sheet 13 0f 15 515 US 2007/0263524 A1 Patent Application Publication Nov. 15, 2007 Sheet 14 0f 15 ma AA A U mwA\/h?\ A A A A A US 2007/0263524 A1 AUA“ .‘ U V u AU U V \ \.\ w u w Aw71Aufl,i0z A % Patent Application Publication Nov. 15, 2007 Sheet 15 0f 15 710 E615 US 2007/0263524 A1 Nov. 15, 2007 US 2007/0263524 A1 OPTICAL MEDIA FORMATS AND METHODS OF MAKING SAME RELATED APPLICATIONS [0001] The present application is related to and claims the bene?t of US. Provisional Application Ser. No. 60/711,616 ?led Aug. 26, 2005 and is herein incorporated by reference in its entirety. BACKGROUND Field of the Invention [0002] The present invention relates generally to optically readable media. More speci?cally, apparatuses, products and devices consistent With the invention are disclosed that include numerous con?gurations for encoding information both data layers on top substrate and a reactive dye or corrosion chemistry in bonding layer; [0007] FIG. 3 illustrates a cross section of a combined CD and DVD embodiment consistent With the invention With a protective lacquer over the CD re?ective layer before bond 111%; [0008] a CD lacquer layer before bonding; [0009] FIG. 5 illustrates a cross section of a limited play DVD With a CD recordable layer embodiment consistent With the invention; [0010] FIG. 6 illustrates a cross section of a DVD embodi ment consistent With the invention With tWo standard DVD bonded back to back, Wherein at least one layer is limited on at least one substrate and/or data layer With at least one Play mechanism, chemical, agent, and/or process for limiting the [0011] time period that at least a portion of the encoded information can be read and/ or accessed by an optical beam and/or reader capable of reading information encoded thereon. SUMMARY OF THE INVENTION [0003] A dual format optically readable medium is dis closed. A ?rst substrate includes data encoded information that is optically readable by an optical beam of a pre-selected Wavelength. The ?rst substrate is conjoined With a second substrate that includes data encoded information readable by an optical beam of a pre-selected Wavelength. The tWo FIG. 4 illustrates a cross section of a combined CD and DVD embodiment consistent With the invention Without FIG. 7 illustrates a cross section of a DVD record able the LO layer With L1 prerecorded layer embodiment consistent With the invention, Wherein the bonding layer includes a read limiting agent; [0012] FIG. 8 illustrates a cross section of a DVD record able on the L0 side With a limited play DVD on L1 side embodiment consistent With the invention; [0013] FIG. 9 illustrates a cross section of a limited play DVD With a permanent play DVD read from the top side embodiment consistent With the invention; [0014] FIG. 10 illustrates a cross section of a limited play substrates are con?gured so as to alloW the reading of the data encoded information stored on each substrate. At least one of the substrates includes a read inhibiting material that DVD With a permanent play DVD recordable layer embodi ment consistent With the invention; prohibits reading of the data encoded information on the ?rst substrate, second substrate, or both substrates after a prede termined period of time. The format of the data encoded information is selected to be readable by an optical beam and may be selected from the formats of, for example, Compact [0015] FIG. 11 illustrates a cross section of a limited play HD-DVD dual layer top substrate bonded With a DVD embodiment consistent With the invention, Wherein either or both the HD-DVD layer or the DVD layer are limited life Disc, CD-ROM, CD-WORM, CD-Interactive, DVI, CD Erasable Magneto Optic, Optical Digital Data Disc, ODD, Video Disk, Interactive Video Disc, Blu-ray, High De?ni tion-DVD, Digital Versatile Disc, DVD-R, DVD-Video, DVD-RAM, DVD-Audio, DVD-RAM, DVD-RW, DVD+ RW, DVD+R, DVD-Video, Super Audio CD, Holographic Versatile Disk, CD-R, CD-RW, CD-Video, Enhanced Ver satile Disc, Digital Versatile Disc Recordable, Digital Mul tilayer Disc, and Blu-ray recordable. The present disclosure also discloses novel dual format combinations that do not include a read inhibiting material and/or mechanism. Also disclosed are optical media capable of storing content of differing durationsia limited duration and a persistent duration. layers; [0016] FIG. 12 illustrates a cross section of a Blu-ray data layer(s) combined With DVD data and/or recordable layers embodiment consistent With the invention; [0017] FIG. 13 illustrates a cross section of a Blu-ray data layer(s) combined With DVD data and/or recordable layers embodiment consistent With the invention; [0018] FIG. 14 illustrates a cross section of a Blue-ray top data layer (dual layer shoWn) combined With HD-DVD data layer (dual layer shoWn) read from the bottom embodiment consistent With the invention; and [0019] FIG. 15 illustrates a cross section of a DVD Recordable L0 layer With a L1 prerecorded layer embodi ment consistent With the invention. BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION [0004] These and other features, aspects and advantages of the present invention Will become better understood With [0020] reference to the folloWing description, appended claims, and ments of the present invention as illustrated in the accom accompanying draWings Where [0005] FIG. 1 illustrates a cross section of a combined CD and DVD embodiment consistent With the invention; [0006] FIG. 2 illustrates a cross section of a combined CD and DVD embodiment consistent With the invention With Reference Will noW be made in detail to embodi panying draWings. The same reference numbers may be used throughout the draWings and the folloWing description to refer to the same or like parts. The folloWing description is presented to enable any person skilled in the art to make and use the inventive body of Work. Descriptions of speci?c embodiments and applications are provided only as Nov. 15, 2007 US 2007/0263524 A1 examples, and various modi?cations Will be readily apparent to those skilled in the art. For example, although many of the examples are described in the context of certain data type combinations any single data type may be made limited play, it should be understood that embodiments of the present invention could be used to in any data type combinations even those combinations not expressly stated, or the like. Similarly, although for the sake of illustration many of the examples describe a read limiting agent and/or mechanism in the bonding layer, those of ordinary skill in the art Will appreciate that the apparatus, devices and products of the present invention can be applied to any suitable to a read limiting agent anyWhere in the optical medium. The general principles described herein may be applied to other embodi ments and applications Without departing from the spirit and scope of the invention. Thus, the present invention is to be accorded the Widest scope, encompassing numerous alter natives, modi?cations, and equivalents consistent With the principles and features disclosed herein. For purpose of clarity, details related to technical material that is knoWn in the ?elds related to the invention have not been described in detail so as not to unnecessarily obscure the present inven tion. OvervieW [0021] In one embodiment consistent With the invention a limited life CD, CD-ROM, and/or CD-R optical disc utiliZ ing a corrosive agent and/ or agent for degrading the integrity of a re?ective layer and/or portion there of located in a layer and/or region adjacent to the re?ective layer of the disc is described. [0022] In another embodiment consistent With the inven tion a limited life CD, CD-ROM, and/or CD-R utiliZing a dye in the optical path of the 780 nm laser is described. The optical disc employs tWo substrates bonded together With a dye adhesive While the data layer resides on top of the substrate stack at approximately 1.2 mm above the bottom surface of the layered disc. [0027] In another embodiment consistent With the inven tion a limited play DVD including recordable and dual layer disc halves using a dye material to inhibit the ability of the reading laser to read a data layer Within the optical disc is disclosed. In an overlapping embodiment a permanent play and/or recordable DVD layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. [0028] In a further embodiment consistent With the inven tion an optical disc combining HD-DVD, HD-DVD-R/RW and/or DVD/DVD-/+R/RW data layers Within one disc Where any one or more of the data and/or recordable layers is limited play is disclosed. In an overlapping embodiment, the limited play mechanism is a corrosive agent that is adjacent to one or more re?ective layer. In a further over lapping embodiment a permanent play and/or recordable DVD layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. In yet another overlapping embodiment the read limiting agent is a dye that inhibits the reading of at least one data layer. In an overlapping embodiment With the dye, a permanent play and/or recordable layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. [0029] In another embodiment consistent With the inven tion an optical medium combining HD-DVD, HD-DVD-/+ R/RW and CD, CD-ROM, CD-R, and/ or CD-RW data layers Within one disc Where any one or more of the data and/or recordable layers is limited play is disclosed. The limited play mechanism is selected from a corrosive material, dye material and/or combinations thereof. If the limited play mechanism is a corrosive material it is located adjacent to at least one re?ective layer. In an overlapping embodiment a permanent play and/or recordable layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. [0030] In an embodiment consistent With the invention an optical medium combining Blu-ray and DVD data and/or In yet another embodiment consistent With the recordable layers Within one disc Where any one or more of invention a limited play DVD combined With a CD data the data and/ or recordable layers is limited play is disclosed. The limited play mechanism is selected from a corrosive material, dye material and/or combinations thereof. If the limited play mechanism is a corrosive material it is located adjacent to at least one re?ective layer. In an overlapping [0023] layer or recordable layer is described. In yet still a further embodiment a corrosive agent and/or agent for degrading the integrity of a re?ective layer and/or portion thereof located adjacent to one or more re?ective layers of the DVD and/or CD data layer is described. embodiment a permanent play and/ or recordable layer sur vives after the limited play mechanism is activated and the [0024] In a further embodiment consistent With the inven limited play layer(s) has ceased to play. tion a dye material is incorporated in the optical path of the reading laser. [0031] In another embodiment consistent With the inven tion an optical medium combining Blu-ray and HD-DVD [0025] In another embodiment consistent With the inven tion a permanent play and/or recordable layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. data and/or recordable layers Within one disc Where any one or more of the data and/or recordable layers is limited play is disclosed. The limited play mechanism is selected from a [0026] In an embodiment consistent With the invention a limited play DVD including recordable and dual layer disc halves using a corrosive material and/or an agent for degrad ing the integrity of at least one re?ective layer and/or portion thereof in a layer adjacent to any re?ective layer Within the corrosive material, dye material and/or combinations thereof. If the limited play mechanism is a corrosive material it is located adjacent to at least one re?ective layer. In an overlapping embodiment a permanent play and/or record able layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. optical disc is disclosed. In an overlapping embodiment a [0032] permanent play and/ or recordable DVD layer survives after the limited play mechanism is activated and the limited play layer(s) has ceased to play. compact disc (hereafter “CD”) includes a mechanism, chemical, agent and/or process for limiting the period of In one embodiment consistent With the invention a time encoded information stored on the CD can be read Nov. 15, 2007 US 2007/0263524 A1 and/or accessed. The mechanism, chemical, agent and/or to any material that prevents the reading beam from reading process for limiting the access time can be applied to CDs at least a portion of any data region after a predetermined time. Corrosive material refers to any material that degrades the integrity of at least a portion of any re?ective layer and thus prevents the reading beam from reading a portion of any data region after a predetermined time. that have the encoded information encoded during the manufacturing process (i.e., CD-Read Only Memory, here after “CD-ROM”) and/or encoded information encoded by recording directly onto the CD (i.e., CD-Recordable and/or CD-ReWritable and the like). Further, the mechanism, chemical, agent and/or process for limiting the access time is independent of the type and/or kind of data and/or information encoded on the CD (i.e., audio, video, data, softWare, images, text, games, combinations thereof, etc.). [0036] The folloWing U.S. patents and patent applications are hereby incorporated by reference in their entirety. U.S. Pat. Nos. 6,641,886; 6,838,144; 6,511,728; 6,537,635; 6,839,316; 6,678,239; 6,011,772; 6,343,063; 6,434,109; 6,756,103; 6,917,579; and Us. patent application Ser. Nos. CD standards, put forth by industry groups such as ECMA International, describe the technical and manufacturing aspects of the various CD formats, i.e., CD-Audio, CD ROM CD-Recordable, CD-ReWritable, CD-Interactive, CD [0037] Video. present invention Will be presented in more detail in the [0033] In yet another embodiment consistent With the invention an optical media that includes at least two different types of data structures and/or data formats and at least one mechanism, chemical, agent and/or process for limiting access to the data region of either type of data structure and/or data format, all the types of data structures and/or data formats contained on the optical media, and/ or portions 10/162,417; 10/016,263; 10/163,473; 10/163,855; 10/163, 472; 10/651,627; 60/627,209; and 60/627,386. These and other features and advantages of the folloWing detailed description and the accompanying ?gures Which illustrate by Way of example the principles of the invention. Compact Disc [0038] In one embodiment consistent With the invention a compact disc (hereafter “CD”) includes a mechanism, chemical, agent and/or process for limiting the period of thereof is described. This embodiment includes, for example, combinations of at least tWo data structures and/or time encoded information stored on the CD can be read data formats selected from Read Only Memory (ROM), Write Once, Read Many (WORM), Interactive (I), Erasable process for limiting the access time can be applied to CDs (E), CD-ROM, CD-WORM, CD-I, DVI, CD-EMO, OD3, ODD, Video Disk, IVD, Blu-ray, HD-DVD, DVD, DVD-R, DVD-Video, DVD-RAM, DVD-Audio, DVD-RAM, DVD RW, DVD+RW, DVD+R, DVD-Video, SACD, variants of the above, and/ or any data structure and/ or data format that is readable by an optical beam and/or optical reading device, including holographic and 3-D optical storage devices. In this embodiment, the at least tWo data structures and/or data formats may be accessed by the reading beam(s) through the same substrate layer and/or substrate side, i.e., Without physically ?ipping the disc over; each through a unique substrate layer and/or substrate side, i.e., physically ?ipping the disc over to access the data of the other type; or a and/or accessed. The mechanism, chemical, agent and/or that have the encoded information encoded during the manufacturing process (i.e., CD-Read Only Memory, here after “CD-ROM”) and/or encoded information encoded by recording directly onto the CD (i.e., CD-Recordable and/or CD-ReWritable and the like). Further, the mechanism, chemical, agent and/or process for limiting the access time is independent of the type and/or kind of data and/or information encoded on the CD (i.e., audio, video, data, softWare, images, etc.). CD standards, put forth by industry groups, such as ECMA and ISO, describe the technical and manufacturing aspects of the various CD formats, i.e., CD-Audio, CD-ROM CD-Recordable, CD-ReWritable, CD Interactive, CD-Video. combination thereof. In an overlapping embodiment consis [0039] tent With the invention at least one data structure and/or data structure based on a 1.2 mm thick molded substrate With a format may be accessed by the reading beam(s) through the data layer on the top surface coated With a re?ective layer. The data layer is read from the bottom side of the substrate same substrate layer and/or substrate side, i.e., Without physically ?ipping the disc over; each through a unique substrate layer and/or substrate side, i.e., physically ?ipping the disc over to access the data of the other type; or a combination thereof. [0034] In still another embodiment consistent With the invention an optical media includes a mechanism for record ing information and storing it on the optical media and a mechanism, chemical, agent and/or process for limiting the period of time the recorded information is accessible. The data format recorded is not limited to CD, DVD, High De?nition, Blu-ray, 3-D and/ or holographic data formats and includes any recordable data format. The various CD formats generally adhere to a disc by a 720 nm. laser. [0040] In one embodiment consistent With the invention a limited play optical CD can be constructed using a corrosive material layer adjacent to the re?ective layer. The corrosive agent responds to a stimulus and/or triggering event, such as for example, exposure to oxygen, Which causes the corrosive agent to react With the re?ective layer such that the associ ated data layer, or a portion thereof, is no longer readable by the read laser of the reading device. [0041] In another embodiment consistent With the inven tion a 1.2 mm thick optically transparent substrate is con structed With multiple layers, at least tWo, of molded sub [0035] The speci?cation frequently makes reference to “substrates,”“dye material,” and “corrosive material.” For strates. TWo 0.6 mm thick substrates are bonded together using a reactive dye material to form a 1.2 mm. thick purposes of clarity, substrate is meant to include any struc tural member of an optical medium used for support and/or to receive a subsequent layer such as for example, a data substrate. HoWever, it should be noted that tWo halves and/or substrates of equal thickness are not required, for example, layer, re?ective layer, bonding layer, buffer layer, lacquer layer, and additional substrate layer(s). Dye material refers one substrate could be 0.4 mm thick and the other 0.8 mm thick and variations thereof. Moreover, the total overall thickness of 1.2 mm is just to comply With the speci?cations Nov. 15, 2007 US 2007/0263524 A1 set forth by ECMA, ISO, and the DVD Forum so that discs Will play in a large percentage of the players currently in the homes of consumers. However, as the standards bodies change the speci?cations so too the embodiments consistent With the invention can be changed. This applies for CD, DVD, High De?nition, Blu-ray, and other next generation optical media. The bottom substrate, or L0 substrate as it is referred to in a DVD construct, Would be a blank disc With no data structures molded on either surface of the L0 substrate. The second substrate is molded With a CD data layer or recordable structures on the top surface. The surface is then coated With a re?ective layer or recordable layers to complete the disc according to its format speci?cations and as speci?ed by disc standards bodies such as, for example, ECMA and ISO. The reactive dye in the bonding layer, When exposed to a stimulus and/or triggering event, such as for example exposure to oxygen, Will disable the ability of the laser to read or record data from the disc. [0042] The above embodiments do not require that the limited play mechanism, i.e., corrosive agent and/or reactive dye, be an entire layer or be throughout a single layer and either can be present in limited regions of the media. For example, the limited play mechanism can be localiZed to a region and/or regions that prevent the entire encoded infor mation stored on the media from being read by the reading beam. Alternatively, the regions With the localiZed mecha nism Will be the regions associated With the limited play mechanism. semi-re?ective ?lms, metallic semi-re?ective ?lms, dielec tric ?lms, and/or combinations thereof. [0047] Metallic semi-re?ective ?lms have an effect on the reading of the 780 nm laser used to read the CD layer. Dielectric ?lms can be made Which are transparent at 780 nm and re?ective at 650 nm. A combination of semi re?ective ?lms may also be used to form a layered semi re?ective ?lm. A mechanism for limited the time a re?ective layer and/or semi-re?ective layer can be read by a reading beam and/or for limiting the integrity of a re?ective layer and/or semi-re?ective layer With the inclusion of a dye, corrosive material and/ or other reading limiting agent in the optical path and/or adjacent to a re?ective layer and/or semi-re?ective layer. For example, in one embodiment con sistent With the invention Wherein the CD data layer and DVD data layer are read from one substrate side a corrosive material eliminates the L0 semi -re?ective layer and removes that re?ected signal from that layer after a prede?ned period of time. [0048] In another embodiment consistent With the inven tion, thicker, full re?ective layers are not affected by the corrosive material. This can be accomplished either by the bulk properties of materials (thick ?lm vs very thin) similar to the semi-re?ective ?lm or by changing the full re?ective layer to a different material such as Au, or silver alloy that does not get impacted by the corrosion mechanism. Thus, providing an optically readable medium With tWo time scales of accessability. CD/DVD Hybrid [0043] Combining the functionality of a CD or DVD together on one disc has been recently accepted by the music industry With the release of a Dual Disc product. As this disc does not meet the original Philips Red Book speci?cations for disc thickness, it is unique in that it has received industry acceptance due to its compatibility With the majority of players in the market, While technically not meeting thick ness speci?cations. [0044] In an embodiment consistent With the invention limited play media constructs With modi?ed disc thicknesses are disclosed. In this embodiment a thin CD is placed back to back With a thin DVD. The CD, DVD, portions of either and/or both, or both disc types include a limited play mechanism, such as for example, a dye in the optical path and/or corrosion of the re?ective layer or portions thereof. As described above, the CD substrate can be, for example, an audio, ROM, recordable, or reWritable disc While the DVD side can be, for example, a DVD-5, an inverse DVD-5, DVD-9, DVD-Recordable, or DVD-ReWritable. These tWo substrates With associated data structures, recording layers, and appropriate re?ective layers can be combined together [0049] FIG. 1 illustrates an embodiment consistent With the invention that includes a limited play CD data layer 40, DVD data layer 30, or both. The bonding resin 15 is in the optical path of the CD read laser 25. With a re?ective layer 30 on L0 10, the CD laser 25 is not blocked by this ?rst re?ective layer. The CD laser 25 then reads the L1 5 data through the bonding resin 15 that includes a reactive dye material that absorbs the read laser after a predetermined period of time. In this embodiment the CD data is of limited duration and/ or limited accessability. The L1 layer 5 is caped With a protective layer 45. Alternatively, the semi-re?ective 30 L0 layer 10 is bonded With a material that results in corrosion of the L0 10 re?ective layer 30 after a prede?ned period of time. This con?guration degrades the DVD re?ec tive layer 10 and creates a limited play DVD layer because the re?ectivity deteriorates to the point that the optical reading beam 35 is not re?ected back in a su?icient manner to all it to be read. In this con?guration the CD data layer 40 is permanent play. [0050] FIG. 2 illustrates an optical medium as in FIG. 1, hoWever the DVD portion is made using an inverse DVD-5 as disclosed in Us. patent application Ser. Nos. lO/l 63,473, in any combination. l0/l63,855, l0/l63,472, l0/837,826, l0/l63,82l, 10/651, [0045] 627 and Us. Pat. No. 6,756,103, all hereafter incorporated by reference in their entirety. In this embodiment, the L1 In yet another embodiment consistent With the invention a CD data layer and a DVD data layer use tWo substrates bonded together and are read from one substrate side. [0046] In still another embodiment consistent With the invention an optical medium includes encoded information With tWo separate life times, a limited life and an inde?nite life. In this embodiment the medium is played and/or read, for both DVD and CD, from one substrate side. The re?ec tive layers can be selected from metallic ?lms, dielectric disc 5 has CD data structures on the top side, and DVD data structures on the bottom of the same disc half 5. (i.e., data structures on both sides of the top disc half). This embodi ment enables the use of bonding resins 15 based on either corrosive materials as in the examples above or dye mate rials as the bonding layer is located Within the optical path of the reading beam(s). Both metallic and dielectric semi re?ective layers can be used. Metallic semi-re?ective ?lms do have an effect on the reading of the 780 nm laser used for
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
advertisement
© 2021