摘要:
In an optical information processor such as an optical disc apparatus, when a light beam is irradiated to a plurality of tracks on an information recording medium, the plurality of tracks act as a diffraction grating. Areas in which light receiving parts of a light detector are arranged are determined by a track pitch, a wavelength and a numerical aperture of a condenser lens so that the light detector detects only a change in a light intensity due to an interference between a 0-order diffracted light ray and a 1-order diffracted light ray.
摘要:
An optical memory apparatus employs an optical disc having a plurality of guide-grooves in spiral and concentrical form and a plurality of flat tracks each arranged between adjacent two of the guide-grooves for recording information thereon, and the depth of the guide-grooves is suitably selected to increase the degree of modulation of a track cross signal, thereby performing a stable cross track counting by the use of the track cross signal and a tracking signal. One feature of the invention relies in that the modulation degree of the track cross signal is in the range between 30 and 60%. A second feature of the invention is that the guide-grooves are formed into a V shape and have an optical depth of .lambda./6 to .lambda./5 (.lambda. is the wavelength of the light used). In accordance with the invention, not ony a stable cross track counting is realized, but also the tracking signal is not practically varied with variations in the depth of the guide-grooves, thereby ensuring a highly accurate and stable tracking control.
摘要:
In an optical information recording and reproducing apparatus having a laser light source and an optical system so that a beam from the laser light source is irradiated through the optical system on an information recording medium to record and reproduce information, an accousto-optic modulator is disposed in the optical system for receiving the beam from the laser light source, and a modulation unit is provided which comprises an oscillator for generating a plurality of signals at different frequencies, a modulator for modulating the outputs of the oscillator and an adder for adding together the outputs of the modulator.
摘要:
An optical information processing apparatus uses an optical disk having correction marks such as mirror surfaces or wobbled pits intermittently arranged along a guide track. In a reproduce mode, tracking control is effected by correcting a tracking signal by a tracking offset component detected by the correction marks. In a record or erase mode, the track offset correction is deactivated and record or erase operation is controlled in accordance with an output level of the detected track offset component so that incomplete eraser of recorded data is prevented.
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:
A magneto-optic memory apparatus is disclosed in which a laser beam is focused on a recording medium having a perpendicularly-magnetized film, the intensity of said laser beam is caused to correspond to reproducing, recording and erasing operations, an external magnetic field is applied to the recording medium at least in recording and erasing periods so that the magnetic field in the recording period is opposite in direction to the magnetic field in the erasing period, a light quantity signal corresponding to the light quantity reflected from the recording medium and a magnetization signal corresponding to data recorded on the recording medium are produced by using the reflected light from the recording medium, at least one of the light quantity signal and the magnetization is amplified by a variable gain amplifier so that an amplified value in the erasing period is nearly equal to an amplified value in the reproducing period, a defect on the recording medium is detected from the output of the variable gain amplifier in the erasing period, and defect information thus obtained is utilized to record data in a non-defective region of the recording medium.
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:
In an optical information recording apparatus in which a plurality of light beams are focused on a disc to form a write/read spot or an erase spot, the position of the light spots on a track of the disc is detected to control the distance between the light spots or the length of the light spots, so that even when the positions at which the light spots are formed differ in the radial direction of the disc, uniform and accurate write/read/erase of information can be effected irrespective of the light spot positions.
摘要:
An optical recording apparatus wherein in front and rear of a first light spot for recording predetermined information along a guide groove provided in a recording medium beforehand, two second light spots and two third light spots are arranged along the guide groove and in a manner to mutually deviate from the center of the guide groove; the second light spots are arranged in an area with no information recorded therein, while the third light spots are arranged in an area with the information recorded therein; and the position of the first light spot is controlled on the basis of the difference between the quantities of light of the second light spots and the difference between the quantities of light of the third light spots, so as to track the information.
摘要:
A focus error detection apparatus and an optical disk apparatus comprising a focusing lens for focusing reflected light coming from a light reflecting surface which is to be adjusted at the focal point of a projected light beam; a beam splitter means for dividing the output light of said focusing lens into a first and a second focused light beam; a first and a second photo-detector disposed respectively on the optical paths of said first and said second focused light beam, one of which is located behind the convergence point of said first focused light beam and the other of which is located before the convergence point of said second focused light beam, each of them generating outputs proportional to the amount of light within a predetermined region of the received light image, when it varies so that it is enlarged; and a circuit generating a focus error signal by using the difference between the outputs of said two photo-detectors.