Abstract: In an optical recording and reproducing method and an apparatus employed for effecting the method, in a light beam of a wavelength .lambda.1 is converted by a laser unit into a light beam having a wavelength .lambda.2 which shorter than the wavelength .lambda.1 through employment of a wavelength converting element, and the light beams with wavelengths .lambda.1 and .lambda.2 are converged at approximately the same spots on a recording medium. For recording a signal, a light intensity of the light beam of the wavelength .lambda.1 projected onto the recording medium is arranged to be a light intensity for not effecting recording of the signal independently, and recording of the signal is effected through modulation of at least the light beam of the wavelength .lambda.2 to be high or low intensity according to the signal to be recorded. For recording or reproducing signals, focus control and tracking control are effected by detecting only the light beam of the wavelength .lambda.

Abstract: In a tracking control apparatus, a tracking error signal having a level of a positional shift of a beam of light projected through an optical head onto a recording medium is detected based on a reflected light from the recording medium, and the optical head is controlled so that a beam of light scans on the track to be recorded or reproduced based on the tracking error signal. Offset values of the tracking error signal on adjustment tracks which are predetermined among a plurality of tracks of the recording medium are detected, and then coefficients of a predetermined approximate equation approximately representing an offset value characteristic on the track based on the detected offset values are calculated. Further, an offset value corresponding to the track to be recorded or reproduced is calculated based on the first approximate equation with the calculated coefficients, and an offset value of the tracking error signal is corrected based on the calculated offset value.

Abstract: The temperature around the tracking actuator is detected with a temperature sensor, and the characteristics of an equivalent digital filter are changed to match the characteristics of the tracking actuator at the detected temperature. When the temperature is low, a current is applied to the focus control coil to raise the temperature of the tracking actuator, thereby essentially matching the transfer functions of the tracking actuator and the equivalent filter.

Abstract: A data-track search apparatus is provided with: a tracking error detection unit for detecting a positioning error between a light beam on a record carrier and a track; a moving unit for moving the light beam on the record carrier in a direction traversing the tracks on the record carrier; a focusing control failure detection unit for detecting a focusing control failure, and a control unit for controlling the moving unit in response to an output signal from the tracking error detection unit during the search for a desired track. The control unit regulates the moving unit so as not to accelerate but to decelerate the moving unit in the event of a focusing control failure.

Abstract: In a first optical disk, a plurality of sets of bit information record cells, each cell including a plurality of bit information record cells, and a plurality of clock marks are formed along a track line on a substrate, and the bit information record cells are formed for example as pits, wherein the recording or reading of a bit of information to or from the bit information record cells is effected with a laser head. The information record cells are arranged at mutual intervals smaller than the minimum read distance of the laser head, while the clock marks are provided so as to have a distance from a set of bit information record cell which is larger than the minimum read distance of the laser head so that the clock marks can be recognized by the laser head to be used for synchronization. Then, the recording density can be improved. In a second optical disk, track recognition marks are arranged as d spiral at equiangular distances so that there are an odd number of track recognition marks per track unit.

Abstract: A data recording/reproducing device has a pickup for recording/reproducing information on disk which has tracks formed on a recording area and a ROM area. A track access device for moving the pickup from a starting track at which the pickup is presently located to a target track includes a moving arrangement for moving the pickup in a direction crossing tracks, a tracking error signal generator for generating an analog signal representing the crossing of the tracks by the pickup, and position detector for detecting the position of the pickup in either one of the recording and ROM areas. Also, for processing the tracking error signal, an amplifier, an offset adder and hysteresis comparator are provided, each having differing operating parameters when the pickup is located in the recording area and then when it is located in the ROM area.

Abstract: A tracking control target position adjusting track is provided on a recording carrier, where the track contains a preliminarily recorded first position-adjusting signal adjoining one side of track and a second position-adjusting signal adjoining the other side of track. While the reproduction position set on the target-position adjusting track, the tracking control apparatus adjusts the tracking-control target position based on reproduced first and second position-adjusting signals. As a result, the tracking control apparatus can precisely adjust the tracking control target position, thus providing quite satisfactory interchangeability with the corresponding apparatuses.

Abstract: A tracking control apparatus is disclosed, in which a light beam is focused on an optical recording medium to form a light spot thereon, and a tracking error signal corresponding to a maximum or minimum point of total reflected light from a portion of the optical recording medium, which is irradiated by the light spot, is detected and used as a desired value for tracking servo control, whereby accurate tracking servo control can be made without producing any offset even when the surface of the optical recording medium is inclined or the optical axis of the light reflected from the optical recording medium deviates from a proper direction.

Abstract: During the storing of a tracking error signal and an index detection signal in memories in relation to rotating means for a recording medium, an error is detected when the number of index detection signals is other than one and afrer the storing of the signal in the memory the missing reproduced index detection signal is interpolated in accordance with the index signal stored in the memory. Also, the stored index detection signal and the reproduced index detection signal are compared in phase so as to determine whether the stored tracking error signal is to be applied to a tracking control system. The memory for storing tracking error signal and the memory for storing index detection signal are combined in one unit.

Abstract: In an apparatus in which information is reproduced by projecting/receiving an optical beam to/from a recording carrier having a large number of information tracks, tracking control is performed so as to maintain a reproducing position on an information track by supplying a track deviation signal to an actuator. If this track deviation signal becomes asymmetric by an inclination, etc. of the recording carrier so that a shock is applied to the apparatus, jumping out of a track occurs, resulting in slip-off of the optical beam from the reproducing position. This slip-off can be prevented by detecting a position of a movable support member carrying a focusing lens for projecting and receiving the optical beam and feeding back the position signal to the tracking control system, or by extracting a low-frequency component of an output signal of a control circuit and feeding back the extracted signal to the tracking control system.

Abstract: A velocity detection method and an apparatus therefor, in which the relative velocity between a light beam and tracks is detected on the basis of a period for which the light beam crosses the tracks, and under the condition that the light beam has passed by a predetermined position on the way to the target track, the detected relative velocity is compared with a predetermined velocity value so that when the detected relative velocity is larger than the predetermined velocity value the detected relative velocity is invalidated on the assumption that erroneous detection is generated by noise.

Abstract: A data-track accessing apparatus effectively eliminates external disturbance components from a track-deviation signal and correctly locates an objective track at an extremely fast speed. The apparatus includes an actuator which transfers a light beam in a direction of traversing tracks, a track-deviation detecting circuit which detects an amount of track deviation when the light beam traverses the tracks, a binary-coding circuit which converts the detected track-deviation signal into a binary-coded signal, an external-disturbance-component removal circuit which removes external disturbance components from the binary-coded track-deviation signal, and a speed-discriminating circuit which discriminates the moving speed of the light beam into multiple stages based on an output signal from the removal circuit.

Abstract: A track search apparatus is composed of an actuator such as voice coil motor for moving a light beam to traverse tracks, a position detector for detecting that the light beam has reached a predetermined position in front of a target track, a velocity detector for detecting the velocity of the light beam, and acceleration/deceleration controller such as microcomputer for applying, to the actuator, a driving signal according to the output from the velocity detector when a signal is generated from the position detector.

Abstract: This invention relates to a method of determining the optimal recording power for an optical disk apparatus.

Abstract: A method of and an apparatus for setting into operation a focusing control for bringing a focal point of a beam onto a recording surface of an optical disk such that the beam reproduces signals from the recording surface, in which a relative velocity between the focal point and the recording surface is detected on the basis of an output of a focusing error detection device for detecting a gap between the focal point and the recording surface and velocity of a displacement device for driving the focal point in a direction perpendicular to the recording surface is controlled on the basis of the detected relative velocity such that focusing control can be stably set into operation by starting focusing control after controlling the relative velocity.

Abstract: In an apparatus in which information is reproduced by projecting/receiving an optical beam to/from a recording carrier having a large number of information tracks, tracking control is performed so as to keep a reproducing position on an information track by supplying a track deviation signal to an actuator. If this track deviation signal becomes asymetric by an inclination, etc. of the recording carrier so that a shock is applied to the apparatus, jumping out of a track occurs, resulting in slipping-off of the reproducing position. This slipping-off can be prevented by detecting a position of a movable support member carrying a focusing lens for projecting and receiving the optical beam and feeding back the position signal to the tracking control system, or by extracting a low-frequency component of an output signal of a control circuit and feeding back the extracted signal to the tracking control system.

Abstract: In an apparatus which focuses a light beam on a rotating recording medium in order to record and/or reproduce information, the light beam on the recording medium is focus controlled so that a prescribed focusing condition is accomplished. By storing a relation between a target position of focus control and the amplitude of a reproduced signal and by obtaining an optimum target position of focus control is accordance with such stored information, the target position of the focus control can be precisely and quickly adjusted, thereby properly controlling the light beam to be focused on the recording medium.

Abstract: In an apparatus for searching a desired track of a recording carrier by transferring and controlling the reproduction position of the pickup for reproducing the signal recorded on a recording carrier on the basis of reference transfer information, the traveling load is measured, and the value of the reference transfer information is corrected according to this measured value, so that the desired track may be searched stably. The transfer motor is driven so that the reproduction position may move at a constant velocity, and the traveling load is measured. The transfer motor is driven so that the moving speed of the reproduction position or the time for moving a specified distance may be predetermined specific value, and by this driving signal, the value corresponding to the traveling load is determined.

Abstract: The present invention discloses a control circuit. An AGC circuit has an input of an x input signal and a gain control amplifier has an input of a z input signal. A division operation of z/x is made by controlling the gain of the gain control amplifier by a gain control voltage issued from the AGC circuit. A division output signal is obtained from an output terminal of the gain control amplifier, and is usable for compensating focus error, tracking error or the like in an optical recording and reproducing apparatus which makes recording and reproducing by a light of laser light or the like. Also included is a switching circuit that allows offset voltages to be reduced.

Abstract: A system for recording or reproducing a signal by focusing and irradiating a light beam on a record carrier from a light source while controlling the light beam to always scan the track on the record carrier is disclosed. A track jump that may occur during recording or reproducing a signal on the record carrier is accurately detected. The reliability of the system is thus improved in such a way as to take appropriate action in case of a track jump.