摘要:
An optical scanning apparatus has a scanning lens with a rotationally asymmetric aspheric surface having individual curvature radii in the main scanning direction and in the sub-scanning direction. The curvature radius in the sub-scanning direction is asymmetrically increased in the lateral direction with the distance from the optical axis. A field curvature aberration which may be generated in the sub-scanning direction on the scanning surface due to an oblique incident of optical beams on the rotating polygonal mirror or the movement of the reflective surface caused by rotation of the rotating polygonal mirror is compensated for by the scanning lens and the focusing properties of the system can be kept at a level of high resolving power.
摘要:
A high-speed image forming method and apparatus is capable of directly controlling a toner by the force of an energy beam. Selected toner particles in a mass of toner adhering to the surface of a transparent drum are irradiated with a laser beam emitted by a laser disposed within the transparent drum and controlled for scanning according to image information. The laser beam separates the selected toner particles from the transparent drum by the force it produces on the particles, and then the separated toner particles are moved to a paper sheet by the force of an electric field produced by a developing electrode. Each toner particle need only be irradiated with the light for a comparatively short period of time, so that an image can be formed at high speed.
摘要:
According to the present invention, a so-called overwrite operation which records new information while erasing existing information can be reliably performed in an information storage system such as optical disk system. In addition, whether the rewriting of recording has been properly done can be verified.
摘要:
A recording medium is provided with a recording film having opto-magnetic characteristics formed on the substrate, with first information being recorded in advance in the form of pit strings of a phase structure. Second information is recorded over the first information through the application of a magnetic field with polarities corresponding to the second information in the presence of the irradiation of a high-power radiation beam, without damaging the record of the first information. The first and second information are produced independently and simultaneously with a single spot in the same area by use of different signal reproduction mechanisms for the first information and second information. The first information (ROM information) is reproduced as the variation in the amount (intensity) of the reflected light from the opto-magnetic recording film, and the second information (RAM information) is reproduced by detecting the rotational angle of the reflected light, based on the Kerr effect, from the opto-magnetic film concurrently with the reproduction of the first information using a single spot.
摘要:
An optical memory device includes a cylindrically-shaped optical information recording medium and at least one optical head disposed around the information recording medium for irradiating the information recording medium with a light spot for recording or reproduction of information. The optical head has light spot moving means incorporated therein for the irradiation position of the light spot. The recording or reproduction of information is achieved by causing the light spot moving means to perform tracking control so that the light spot follows a desired track in an area within a range of movement of the light spot by the light spot moving means (or an infromation recording zone) in a state in which the relative positional relationship between the optical head and the cylindrically-shaped information recording medium in the direction parallel to the direction of the rotation axis of the information recording medium is fixed, with the optical head being not moved. The device can be constructed so that the position of either the optical head or the cylindrically-shaped information recording medium relative to the other in the direction parallel to the direction of the rotation axis of the information recording medium is mechanically moved, thereby making it possible to cahnge the information recording zone in the range of movement of the light spot by the light spot moving means to another information recording zone.
摘要:
A record carrier having a disc-shaped substrate and a recording layer for optically writing information therein is disclosed which includes a guide groove extended in the rotational direction of the record carrier so that a plurality of revolutions of the guide groove are spaced apart from each other in radial directions of the record carrier, and a pit pattern provided between adjacent guide grooves, at positions arranged at intervals in the above rotational direction, for detecting the deviation of a light spot from the center line between adjacent guide grooves. The recording/reproducing operation for this record carrier is performed in such a manner that the first tracking error signal is detected from diffracted light from the guide groove, the second tracking error signal is detected from the pit pattern, and information is recorded in and reproduced from a land formed between adjacent guide grooves in a state that a tracking operation is performed using the first and second tracking error signals. The second tracking error signal detected from the pit pattern is not affected by the tilting of the record carrier and the movement of the light spot. When a tracking signal obtained by adding the first and second tracking error signals to each other, is used in a closed-loop tracking system, a stable tracking operation can be performed. The polarity of the pit pattern is reversed on every track, and hence a polarity pit having a depth of .lambda./4 (where .lambda. indicates the wavelength of a reproducing light beam) is provided in the record carrier, to reverse the polarity of the second tracking signal on every track on the basis of a signal from the polarity pit.
摘要:
Data recording and/or reproduction on or from a recording medium on which tracking signal detection marks are intermittently provided along each track in a pattern wobbling alternately across the track center line with a very small lateral displacement therefrom, wherein data recording area is defined between the tracking signal detection mark. A servo control system for controlling a write/read light spot so as to follow the track with the aid of a tracking signal obtained by detecting the tracking signal detection marks is provided with a low-pass filter circuit having a cut-off frequency lower than the frequency at which the tracking signal detection marks are detected. A data is recorded or reproduced on or from the recording areas of the recording medium while following the track under the control of the servo system. A blank area where data recording is inhibited is provided between the data recording area and the tracking signal detecting mark (prepit) to suppress interference to the data. A particular access prepit pattern which allows track addresses to be at least approximately detected upon passing of the light spot over the track of the recording medium is previously provided together with synchronizing marks in a synchronizing area.
摘要:
An optical disk having a disk-like substrate and a recording layer provided on the substrate. First and second regions are alternately arranged along a rotational direction of the optical disk. The first region includes a pre-formed optically detectable portion having an address area, and the second region has a guide groove serving as an optical guide for a light spot. A track offset detection area is provided for detecting track offset due to inclination of the optical disk and is disposed with respect to the first region and the second region so that the light spot is not affected by the first region and the second region. The track offset detection area is preferably a mirror portion disposed between the first region and the second region.
摘要:
Information play-back apparatus comprising a laser source, a recording medium, a photodetector, a first optical system which conducts a laser beam from the laser source to an information track on the recording medium as a read spot, and a second optical system which conducts a reflected laser beam from the information track to the photodetector through an optical element having the unidirectional lens action, said optical element being arranged in a manner to define an angle of about 45 degrees relative to the direction of the information track, and said photodetector having at least four light receiving portions divided symmetrically about two axes such that at least one light receiving portion is in each of the four quadrants formed by two axes, and one of the axes is parallel to the direction of the information track.
摘要:
A multilayer optical information medium provided with structure in which first and second substrates respectively provided with two to four layers of planar information areas are respectively arranged outside wherein the thickness of the above-described first and second substrates is set in the range of 0.52 to 0.65 mm. The above-described planar information area consists of embossed pits provided, for example on the surface of respective substrates or on the surface of a layer formed by transparent material and a semi-reflective layer provided on the embossed pits. A planar information area arranged in the farthest position from respective substrates is provided with a reflective layer in place of the above-described semi-reflective layer. The planar information area arranged in the farthest position from respective substrates may be constituted by a recording layer and a reflective layer provided on the recording layer.