Abstract: A method of making composite discs continuously, including forming for each disc a first, a second layer, and a third support layer, each support layer being disc shaped and having a first surface with information indicia. An information layer is added to each support layers respectively. The said first and third support layers are positioned in a facing relationship, with the first and third information layers being adjacent. The third support layer is then separated from the third information layer, which thus remains attached to the first support layer. The first and second support layers are then joined. These steps are performed on a manufacturing line with conveyor belts transferring the support layers from station to station.

Abstract: An improved light-readable information recording medium is provided that comprises an optical data storage structure having lands and pits, in which the depth of the pits is about: ? 2 ? n ? m 1 + M T 2 , wherein ? is the wavelength of light used to read the information recording medium, m is the order of interference selected from a group consisting of odd integers, MT is the transverse magnification, and n is the refractive index encountered by the reading light inside the pits. The invention also provides an improved optical reading system with the parameters satisfying the relationship: nd = ? 2 ? n ? m 1 + M T 2 , wherein ? is the wavelength of light used to read the information recording medium, m is the order of interference selected from a group consisting of odd integers, MT is the transverse magnification, n is the refractive index encountered by the reading light inside the pits, and d is the depth of the pits.

Abstract: An improved light-readable information recording medium is provided that comprises an optical data storage structure having lands and pits, in which the depth of the pits is about: ? 2 ? n ? m 1 + M T 2 , wherein ? is the wavelength of light used to read the information recording medium, m is the order of interference selected from a group consisting of odd integers, MTT is the transverse magnification, and n is the refractive index encountered by the reading light inside the pits. The invention also provides an improved optical reading system with the parameters satisfying the relationship: n ? ? ? d ? ? 2 ? m 1 + M T 2 , wherein ? is the wavelength of light used to read the information recording medium, m is the order of interference selected from a group consisting of odd integers, MT is the transverse magnification, n is the refractive index encountered by the reading light inside the pits, and d is the depth of the pits.

Abstract: An insert for a magazine or book has a recording medium compartment defining a top edge, a bottom edge and two lateral side edges. Two of the edges are closed at all times, one of the edges is initially open for passage therethrough of a recording medium into the compartment (and then closed), and another of the edges is initially closed but openable for passage therethrough of the recording medium out of the compartment.

Abstract: A method of making composite discs continuously, including forming for each disc a first, a second layer, and a third support layer, each support layer being disc shaped and having a first surface with information indicia. An information layer is added to each support layers respectively. The said first and third support layers are positioned in a facing relationship, with the first and third information layers being adjacent. The third support layer is then separated from the third information layer, which thus remains attached to the first support layer. The first and second support layers are then joined. These steps are performed on a manufacturing line with conveyor belts transferring the support layers from station to station.

Abstract: An improved optical disc is provided that comprises a substantially transparent substrate, one surface of which carries optical data structures comprising pits and lands radially outward of a clamp area of the disc. In the clamp area a protrusion structure is provided above the first surface to create a clamp thickness greater than the thickness of the rest of the disc. In accordance with the principles of the present invention, only a portion of the clamp area is covered by the protrusions, which emulate a disc having a clamp area of greater thickness. In order to reduce warping caused by shrinkage of material added to the clamp area, the amount of material used to form the protrusions is less than 5% of the amount of material used to form the rest of the clamp area.

Abstract: An improved light-readable information recording medium is provided that comprises an optical data storage structure having lands and pits, in which the depth of the pits is about: λ 2 ⁢ n ⁢   ⁢   ⁢ M 1 + m T 2 , wherein &lgr; is the wavelength of light used to read the information recording medium, m is the order of interference selected from a group consisting of odd integers, MT is the transverse magnification, and n is the refractive index encountered by the reading light inside the pits.

Abstract: Methods for forming a single-side-readable DVD having graphical information viewable from the DVD's frontside disc are provided. A first, frontside disc having a first and a second surface, with the second surface comprising program information and coated with a semi-reflective coating, is bonded to a second, backside disc having a third and a fourth surface. A first portion of the fourth surface comprises spillover program information and a second portion of the fourth surface comprises graphical information. The fourth surface is coated with a reflective coating. During DVD formation, the frontside and backside discs are adhesively bonded back to back so that the second surface of the frontside disc faces the fourth surface of the backside disc. Because the frontside disc comprises a semi-reflective coating, the graphical information on the second portion of the fourth surface of the backside disc is viewable through the frontside disc.

Abstract: An improved light-readable information recording medium is provided that comprises an optical data storage structure having lands and pits, in which the depth of the pits is about: 1 λ 2 ⁢ n ⁢ m 1 + M T 2 ,

Abstract: A method and apparatus for vacuum assisted venting of an injection mold. The apparatus includes a main body structured to be mounted around an outer circumference of the injection mold and configured to facilitate application of a vacuum pressure therein. The method and apparatus are particularly directed towards preventing the accumulation of residual material inside an injection mold and reducing the frequency of disassembly and cleaning required for the injection mold.

Abstract: An improved optical disc is provided that comprises a substantially transparent substrate, one surface of which carries optical data structures comprising pits and lands radially outward of a clamp area of the disc. In the clamp area a protrusion structure is provided above the first surface to create a clamp thickness greater than the thickness of the rest of the disc. In accordance with the principles of the present invention, only a portion of the clamp area is covered by the protrusions, which emulate a disc having a clamp area of greater thickness. In order to reduce warping caused by shrinkage of material added to the clamp area, the amount of material used to form the protrusions is less than 5% of the amount of material used to form the rest of the clamp area.

Abstract: A method and apparatus for vacuum assisted venting of an injection mold. The apparatus includes a main body structured to be mounted around an outer circumference of the injection mold and configured to facilitate application of a vacuum pressure therein. The method and apparatus are particularly directed towards preventing the accumulation of residual material inside an injection mold and reducing the frequency of disassembly and cleaning required for the injection mold.

Abstract: Methods for forming a single-side-readable DVD having graphical information viewable from the DVD's frontside disc are provided. A first, frontside disc having a first and a second surface, with the second surface comprising program information and coated with a semi-reflective coating, is bonded to a second, backside disc having a third and a fourth surface. A first portion of the fourth surface comprises spillover program information and a second portion of the fourth surface comprises graphical information. The fourth surface is coated with a reflective coating. During DVD formation, the frontside and backside discs are adhesively bonded back to back so that the second surface of the frontside disc faces the fourth surface of the backside disc. Because the frontside disc comprises a semi-reflective coating, the graphical information on the second portion of the fourth surface of the backside disc is viewable through the frontside disc. The graphical information does not affect the playability of the DVD.

Abstract: Methods for forming a single-side-readable DVD having graphical information viewable from the DVD's frontside disc are provided. A first, frontside disc having a first and a second surface, with the second surface comprising program information and coated with a semi-reflective coating, is bonded to a second, backside disc having a third and a fourth surface. A first portion of the fourth surface comprises spillover program information and a second portion of the fourth surface comprises graphical information. The fourth surface is coated with a reflective coating. During DVD formation, the frontside and backside discs are adhesively bonded back to back so that the second surface of the frontside disc faces the fourth surface of the backside disc. Because the frontside disc comprises a semi-reflective coating, the graphical information on the second portion of the fourth surface of the backside disc is viewable through the frontside disc.

Abstract: Light-readable information-recording media are fabricated according to a method wherein the back of a production stamper is laser-scribed, diamond-scribed, etched, or marked by other means to produce an image. This production stamper is then used to form a substantially transparent substrate having information recorded on it by means of pits and lands. During the formation of the substrate, the image is transferred from the back of the stamper to the surface of the substrate. The resulting watermark may be visible under normal light conditions. Information-recording media bearing indelible watermarks according to the present invention are also disclosed.

Abstract: Information-bearing discs are fabricated from a first disc and a second disc. The first disc has a first substantially planar surface and a second surface opposite to the first surface. The second surface has first information recorded on it by means of local changes in the distance of the second surface from the first surface. The thickness of the second disc is not equal to the thickness of the first disc and has opposite, substantially planar, third and fourth surfaces. The fourth surface may have second information recorded on it by means of local changes in the distance of the fourth surface from the third surface. The second disc is secured to the first disc so that the fourth surface faces the second surface.

Abstract: Methods and apparatus for recording on DVD-like recording media in which audio content is stored in a high-capacity multi-channel (e.g., six-channel) format are provided. Various channels may use various resolutions. A two-channel audio output may be derived from the multi-channel audio data stream during playback. To facilitate an accurate derivation, the mixing coefficients to be used in generating the derivation can be supplied along with the six-channel audio data.

Abstract: An improved light-readable information recording medium is provided that comprises an optical data storage structure having lands and pits, in which the depth of the pits is about: 1 λ 2 ⁢ n ⁢   ⁢   ⁢ M 1 + m t 2 ,

Abstract: A protective layer is applied to the surface of a compact disc precursor that must be protected from dust during manufacture. The layer is removable and preferably made of ethylene vinyl acetate.

Abstract: Methods and apparatus for recording and playing back multi-channel digital audio having different sampling rates for different channels are provided. Recording is accomplished by sampling a plurality of channels of audio data and arranging the samples of the plurality of channels of audio data in most nearly the order needed during playback. Playback is accomplished by accessing the samples of the plurality of channels of audio data and converting the samples from digital to analog form. The playback may include deriving audio signals in a different format from the format in which the programming is recorded.