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: 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: 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: 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.

Abstract: Audio signal samples taken at different sampling rates are synchronized. A plurality of channels of audio data are sampled at different rates and recognizable synchronization data are added to selected samples of at least one channel of the plurality of channels.

Abstract: A double sided (or higher multiple sided) data storing compact disc for optically recorded data has data surfaces that are separated by a thin film of wavelength selective material that passes light of one frequency and reflects light of a second (or multiple) frequency. The thin film either passively relies upon the inherent interference between light signals reflected from its upper and lower surfaces or is an active material that reflects light of one frequency and transmits light of a second frequency. A further aspect of the present invention is the method for the manufacture of such a multi-surfaced disc.

Abstract: To protect access to information recorded on a light-readable disc, a light-readable disc player provides the user with a unique key each time the user attempts to play the disc. After the user communicates the unique key to a transaction service and satisfies certain preconditions, such as providing payment or account information, the transaction service provides the user with an unlock key. The user communicates the unlock key to the light-readable disc player, which plays the disc only if the user has provided the correct unlock key.

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 second disc is thicker than 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: A dual-layer DVD disc that does not require a stamping step (typically, as part of the 2P prior art manufacturing process) during its manufacture. A polycarbonate substrate is molded and coated with a semireflective data layer in the usual way. A PMMA substrate is molded and coated with a fully reflective data layer. Adhesive is placed on the semireflective data layer, and the fully reflective data layer is transferred from its PMMA substrate to the polycarbonate substrate. The polycarbonate substrate thus ends up with two data layers in conformance with the DVD specifications, and the PMMA substrate can even be recycled for another use.

Abstract: The warping of the surface of a composite compact disc occurring during the bonding of two surfaces together to form the disc is reduced by the use of a curing filter that modulates the intensity of the ultraviolet light used to set the bonding agent. The curing filter may be in the form of a disc having a greater density near the periphery of the disc than at the center.

Abstract: An in-line system for fabricating a double sided compact discs by bonding together an information bearing surface and another surface, has a prestressing station with means for deforming at least one of the surfaces in such away as to not disturb any of the data. It employs an adjustable spacer for maintaining an adjustable separation between symmetrical arcuate portions of the outer circumference of the information bearing surfaces in the bonding station. This adjustable spacer comprises two spacer arms that comprise wedge shaped portions for entry between the edges of said discs and maintaining a displacement of at least the outermost edges of said discs. There is also disc displacement means for bringing together the two information bearing surfaces by displacement of at least one of said information bearing surfaces orthogonal to the plane of the surfaces.

Abstract: A process for determining the Start Program Point for a compact disc recording of data first recorded on an other medium, by measuring with the aid of a microscope the radius of the transition from the first pit/land transition from silence to data, measuring with the aid of an editor for the other medium a delay period of silence intended to be part of the data, calculating the Start Program Point and recording the Start Program Point thus calculated on the compact disc.

Abstract: A method for focusing the objective of an optical pick-up head on the desired information layer of an optical memory device. The focus error signal when the focus servo is in open loop mode is used to determine the location of the information layers (or layer) and to provide a mechanism for providing a signal which can be used to time/trigger the closing of the focus servo, thus providing focus on the desired layer. One example of an embodiment of the invention is an application to a dual layer optical disc.

Abstract: A system for testing compact discs having audio or video information and time subcode information indicating the elapsed time from the beginning of the audio, video or data information thereon in which three microprocessors respectively monitor the HF signal, the radial tracking signal and the decoder digital flags produced by a CD player to produce error signals indicating HF dropout, HF low, modulation amplitude, radial tracking, Burst, Bler, and uncorrectable errors and in which a computer having a memory responds to the time signal produced by the player periodically to transfer the contents of the microprocessors to the memory together with the time of transfer and to reset the microprocessors, thus to record errors and to locate the positions thereof on the disc in terms of the time subcode information. Initially an eccentricity test is performed and the entire test is stopped if the eccentricity is excessive. The computer is programmed to display the test results in various formats.

Abstract: A single or multi-sided, single or multi-layered optical data disc in which graphical information resides beneath all layers of data information, while maintaining playability. The graphical information is fully viewable to a user through the layers of data. The conventional metalization layer is replaced by a thin film dielectric coating that provides the reflectivity of the metal to the reading laser frequency while being highly transmissive of the ambient visible spectrum.

Abstract: A technique for verifying the authenticity of a particular breed of pirated optical discs. By comparing the original source disc with the pirated version in the cross-polarization laser light of a polarimeter, the stress of the pirated replication will be revealed, verifying the existence of piracy.

Abstract: A method for combining CD-ROM and CD-DA audio data on a single compact disc to reduce the amount of noise which is heard when the compact disc is played back on a player which is not specially adapted to play compact discs with both CD-ROM and CD-DA audio data. Presently, there are three (3) methodologies embodying the invention. In the first, the CD-ROM, i.e., CD-ROM boot blocks are placed in Track 1, Index 1; the CD-DA audio tracks are placed in tracks (2, 3, . . . , N) and the CD-ROM data files are placed in track (N+1). In the second, the entire CD-ROM Volume is placed in Track 1, Index 0; the first CD-DA audio track is placed in Track 1, Index 1, and all other CD-DA audio tracks are placed in tracks 2, 3, . . . , N. In the third, the entire CD-ROM Volume is placed in Track 1, Index 0 as in the second. However, in the third, the boot blocks for the CD-ROM volume are repeated in Track 1, Index 1, with all CD-DA audio selections being placed in tracks 2, 3, . . . , N.