Abstract: Increase of jitter in a phase change optical recording medium is suppressed with no extreme decrease in the crystallization speed of the recording layer when the medium is overwritten at a high linear velocity. In addition, in a disk-shaped medium operated at a constant angular velocity, the overwriting is accomplished with the increase of jitter suppressed over the entire area of the medium. Provided is an optical recording method for recording a disk-shaped optical recording medium having a phase change recording layer which is rotated at a constant angular velocity, wherein amorphous recorded marks are formed in the recording layer. In this method, the minimum recorded mark is formed such that WL/ML incrementally or gradually decreases from the radially inner side to the radially outer side of the optical recording medium, when the minimum signal has a length of SL, and when the minimum recorded mark corresponding to said minimum signal has its maximum width of MW, EW is 0.

Abstract: In an optical recording medium comprising a grooved light-transparent substrate, a phase change recording layer, a dielectric layer and a reflective layer, recording is carried out by irradiating a laser beam to the recording layer through an objective lens in an optical system. The recording is carried out in the grooves under the conditions: 0.48≦PT/(&lgr;/NA)≦0.74, and PT≦0.50 &mgr;m wherein &lgr; is a laser beam wavelength, NA is an objective lens numerical aperture, and PT is a track pitch, thereby forming a recorded mark having opposite ends extending out of the groove. This enables high density recording and increases the data transfer rate of a phase change optical recording medium.

Abstract: In an optical recording medium wherein grooves or lands formed on the supporting substrate are used for the recording tracks, and wherein prepits are also formed, production of the supporting substrate and high density recording are facilitated. This medium comprises a supporting substrate and a recording layer on the substrate wherein the surface of the supporting substrate on which the recording layer is formed is formed with alternating continuous convex portions and continuous concave portions which are substantially parallel to each other. The adjacent continuous convex portions are connected by bridging convex portions extending in transverse direction, and the bridging convex portion has a planar configuration that its width is minimum at or near the center between the adjacent continuous convex portions. The supporting substrate is produced by using a master disk which has a resist layer formed with mother patterns of each of the continuous convex portions, continuous concave portions, and prepits.

Abstract: In an optical information medium comprising a supporting substrate, an information recording layer thereon, and a light-transmitting layer wherein a recording/reading laser beam enters the recording layer through the light-transmitting layer, the light-transmitting layer is formed of a resin and has a tensile strength at break of 5-40 MPa, a tensile elongation at break of 15-100%, and a tensile modulus of 40-1,000 MPa. The medium has improved recording/reading characteristics when a laser beam defines a beam spot having a small diameter of up to 300 &mgr;m and the medium is rotated at a high linear velocity of at least 8 m/s.

Abstract: In an optical recording medium comprising a phase change recording layer (4) containing Sb and optionally, Te and/or In as a main component, the recording layer is able to be crystallized to provide a crystallized region which contains rhombohedral crystals consisting essentially of Sb and is substantially free of a crystal phase other than the rhombohedral crystals. When the recording layer contains a rare earth element, Zr, Hf, Ti or Sn as an auxiliary component, the medium has a dielectric layer (31) composed of silicon oxide, silicon nitride, aluminum oxide, or a mixture of zinc sulfide and at least 30 mol % of silicon oxide, disposed contiguous to and in front of the recording layer (4) as viewed from the recording/reading beam incident side. The medium has a high transfer rate and improved thermal stability.

Abstract: In an optical recording medium having a phase change recording layer, recorded marks having a shortest length of up to 350 nm are formed in the recording layer which contains Sb as a main component. This enables formation of microscopic recorded marks which are stabilized in shape and size. The medium remains reliable in that the microscopic recorded marks are improved in thermal stability.

Abstract: When information is recorded in an optical recording medium having a recording layer by irradiating a laser beam thereto through an optical system, the recording is carried out under the conditions: &lgr;/NA≦680 nm and n·Tw≦22 ns wherein the laser beam has a wavelength &lgr;, the optical system includes an objective lens having a numerical aperture NA, the window margin is Tw, and a signal length corresponding to the shortest recorded mark is n·Tw. The method provides for a high transfer rate and minimizes the jitter.

Abstract: Size-enlarged sludge particles 12 having nuclei of objective particles and having a particle size in a range of from 1 &mgr;m inclusive to 2000 &mgr;m exclusive are mixed with slurry containing fine alumina powder so that a mixture is prepared. Then, the mixture is dried by removal of the water content in the mixture. Then, the mixture is baked at a temperature in a range of from 1200° C. to 1500° C. so that alumina on surfaces of the size-enlarged sludge particles 12 are sintered. By the aforementioned method, light-weight alumina particles can be produced with the particle size controlled well to a uniform value.

Abstract: A voice signal from a microphone is processed for compressing and coding in a voice compressor 4. The compressed voice data that the voice compressor 4 outputs is input into a transmission switching section 5. The transmission switching section 5 switches and outputs the compressed voice data to either a UDP transmitter 7 or a TCP transmitter 6 according to a transmission switching signal that the network situation supervisory section outputs. A network situation supervisory section 16 outputs a transmission switching signal which acts so as to transmit with a UDP in case that a network is in a situation with a margin, and the transmission switching signal which acts so as to transmit with a TCP in case that a network is in a confused situation responding to network congestion information that is obtained from a network interface 9.

Abstract: An illuminated switch unit according to the present invention is provided with: a case having a recess, a pair of protrusions provided within the recess and holes corresponding to those protrusions; a movable knob housed within the recess of the case, and provided on the protrusions so as to be able to rock or move up and down; a switch capable of bringing a movable contact provided on an elastic member to be driven by the movable knob into and out of contact with a stationary contact; and a substrate having a light source for illuminating the movable knob, wherein the elastic member is provided with light shielding members for preventing the light from the light source from passing through the holes in the case.

Abstract: In an optical recording medium of land/groove recording system, a sufficient tilt margin and a reduced cross talk are realized simultaneously with a sufficiently increased output.

Abstract: A compressive encoder changes a search area in accordance with an attitude of a camera platform mounting a video camera on the platform. Responsive to a video signal from the video camera, the encoder executes compressive encoding together with motion compensation which uses motion vectors found out within the changed search area. Thus, the possibility that the motion vectors are founded out within the changed search area becomes high and effective compressive-encoding is achieved.

Abstract: Formation of a synchronization mark pattern of excellent readability is enabled in an optical recording disc wherein track jump is required once per one disc rotation in a convenient manner. The optical recording disc comprises a disc substrate 2 and a recording layer 4 on the disc substrate 2, and at least one surface-irregularity region 2b having an irregularity pattern formed therein is provided on the substrate in its non-recording region and circumferentially adjacent to a smooth region. The surface-irregularity region is preferably in the shape of an arc concentric with the substrate, and the surface-irregularity region preferably comprises a plurality of circumferentially extending grooves or a plurality of projections.

Abstract: In a phase change-type optical recording medium of absorption coefficient control structure used by land/groove recording system, difference in reproduction characteristics between the land and the groove is minimized while ensuring sufficient output of the tracking signal. In the optical recording medium of the present invention, light absorption coefficient at the wavelength of said recording/reproducing beam is such that: Ac/Aa≧0.8 when light absorption coefficient in crystalline region is Ac and light absorption coefficient in amorphous region is Aa; relation between groove width WG and land width WL is such that: 0.97≦2WG/(WL+WG)<1.

Abstract: Disclosed are crystals of a compound represented by the formula: and processes for preparing them.

Abstract: In the phase change type optical recording medium of the present invention, loss of reliability by high-temperature storage is prevented, and self-erasure (a phenomenon of partial erasure of the record mark by heat diffusion in the lateral direction during the irradiation of the recording laser beam) is suppressed. There is thus provided an optical recording medium designed for use in a drive system wherein overwriting is conducted at a linear velocity V.sub.0 which satisfies the relation:0.6<V.sub.2nd /V.sub.0 <1.25when V.sub.2nd is the overwriting linear velocity at which the frequency component corresponding to the second harmonic of the frequency of the recording signal used for the overwriting is minimized when the record marks formed by the overwriting are reproduced and measured for such frequency component. Also provided is an optical recording medium adapted for use in a drive system wherein overwriting is conducted at a linear velocity V.sub.

Abstract: A phase change type optical recording medium comprises a dielectric layer 1a, a dielectric layer 1b, a phase change type recording layer and a second dielectric layer in the described order. The recording layer satisfies Ac/Aa.gtoreq.0.8 where Ac is an absorption coefficient of the recording layer in a crystalline region and Aa is an absorption coefficient of the recording layer in an amorphous region. The dielectric layer 1a comprises ZnS--SiO.sub.2 as main components and the dielectric layer 1b comprises a metal nitride or ZnS--SiO.sub.2 having an SiO.sub.2 content of 40 to 80 mol % as main components. At least an area of the second dielectric layer that is in contact with the recording layer comprises a metal nitride, a rare earth oxide, silicon oxide or ZnS--SiO.sub.2 having an SiO.sub.2 content of at least 40 mol% as main components. However, an optical recording medium comprising a dielectric layer 1a having an SiO.sub.

Abstract: Prevented is the reliability loss in phase change optical recording media during high-temperature storage, and also prevented is the phenomenon of self-erase by which a part of record marks having been formed in the media are erased due to the lateral heat diffusion into the recording layer while recording laser beams are irradiated to the media. The optical recording medium disclosed has a recording layer of a phase change type and is applied to driving units for overwriting it at a linear velocity of V.sub.0. The medium is so designed as to satisfy the requirement of 1<V.sub.max /V.sub.0 <1.5, where V.sub.max indicates the linear velocity at which the medium being overwritten has a highest C/N ratio.

Abstract: In a phase change-type optical recording medium of absorption coefficient control structure used by land/groove recording system, difference in reproduction characteristics between the land and the groove is minimized while ensuring sufficient output of the tracking signal. In the optical recording medium of the present invention, light absorption coefficient at the wavelength of said recording/reproducing beam is such that: Ac/Aa.gtoreq.0.8 when light absorption coefficient in crystalline region is Ac and light absorption coefficient in amorphous region is Aa; relation between groove width W.sub.G and land width W.sub.L is such that: x=2W.sub.G /(W.sub.L +W.sub.G).gtoreq.1.03; and the relation: .lambda.max.sup.i <.lambda.u.ltoreq..lambda.min.sup.i, and -100x+123.ltoreq.t.sub.R .ltoreq.-100x+126 are satisfied when the wavelength of a local minimum in reflectance spectrum is .lambda.min.sup.i ; the wavelength of the local maximum in the reflectance spectrum nearest to the .lambda.min.sup.

Abstract: An optical recording medium of phase change type, and in particular, a dual side medium prepared by adhering two single side media is provided. In this medium, deformation of record marks generated in the overwriting due to difference in light absorption between the record marks and the region other than the record marks is prevented by providing a reflective layer of high light transmission, and increase in jitter and failure of track servo and focus servo caused by uneven coating of the adhesive layer and the resin protective layer are prevented. The optical recording medium comprises a substrate, a recording layer of phase change type on the surface side of the substrate, and a reflective layer and a light absorption layer disposed in this order on the surface side of the recording layer.