Pioneer Electronic Corporation

Pioneer Corporation

Alex Bradshaw

Hiroyuki Abe

Kazuhiro Kiyoura

Koichiro Haraguchi

Takashi Suzuki

Yoshio Aoyagi

Yoshiya Nonaka

Seiji Kato

Shinichi Naohara

Norio Matsuda

Motoi Kimura

Takeshi Sato

Hitoshi Yamazaki

Kenichi Takahashi

Hideaki Watarihana

Yuichi Kimikawa

Kiyoshi Furukawa

Kazushige Kawana

Chiaki Hirano

Hideaki Yoshimura

Takeshi Matsumoto

Tomoko Miyagawa

Yoshifumi Fujino

Yoshimichi Nishio

Masakazu Takahashi

Morio Nozaki

Mayumi Takahashi

Two sum output signals from two sets of the photodetector elements located symmetrically each other with respect to a light-receiving center of the photodetector of the optical pickup are amplified individually by two amplifiers. A focus error signal is generated in accordance with a difference between respective output levels of the two amplified signals. The gains of the two amplifiers are adjusted in accordance with the focus error signal. A predetermined bias voltage is applied to the focus error signal line in the focus servo control means in accordance with the focus error signal.

Focus servo controller with collision avoidance and method therefor

A tilt servo apparatus which can correct a tilt error at a high speed and with high precision irrespective of a magnitude of the tilt error even if a response speed of a liquid crystal device decreases is provided. An amount of change and an increase/decrease of a signal intensity are detected by changing a correction value of a tilt error correcting arrangement by a first correction width, and a correction width of the correction value and a correcting direction are determined on the basis of the detection result. When the amount of change of the signal intensity is smaller than a predetermined amount of change, the correction width is changed to a second correction width which is smaller than a first correction width. When it is larger than the predetermined amount of change, the correction width is changed to a third correction width larger than the first correction width. The correction width is also determined in accordance with a change in environmental temperature.

Tilt servo apparatus and control method thereof

A tilt servo control apparatus has a tilt error correcting device for correcting a tilt error caused by a tilt angle defined between a normal at an irradiating position of a laser beam irradiated onto a recording surface of an optical recording medium and an optical axis of the laser beam. The tilt error correcting device is driven based on an intensity of the reflected light of the laser beam irradiated onto the recording surface. The apparatus provides a control to hold a drive value of the tilt error correcting device to a predetermined value in response to a track jump command for changing the irradiating position of the laser beam from the first irradiating position to the second irradiating position that is away therefrom by a distance corresponding to a predetermined number of tracks.

Tilt servo apparatus for optical disc recording/playing apparatus

A focusing bias adjusting apparatus in an optical recording medium playing apparatus, in which a focusing bias adjustment is executed to remove an offset component in a focusing error signal based on each output signal of a split type photodetector in an optical pickup and, thereafter, a tilt adjustment is executed to an optical system so as to maximize a read signal serving as a sum signal of the output signals of the photodetector in order to compensate a tilt angle which is defined by a normal at the irradiating position of a laser beam from the optical pickup on the recording surface of an optical recording medium and the optical axial direction of the laser beam. When the tilt adjusting operation of the optical system of the optical pickup is performed after completion of the focusing bias adjustment, the focusing bias adjustment is executed again.

Focusing bias adjusting apparatus and method in optical recording medium playing apparatus

A focus control apparatus for a multilayer optical recording medium performs an adequate focus jump on a multilayer optical recording medium. Threshold values are set according to the amount of a level change in a focus error signal of a loaded multilayer optical recording medium, and focus jump control is conducted based on the result of comparison between the level of the focus error signal and the set threshold values. Positive and negative threshold values to be compared with the level of the focus error signal to detect a zero-crossing point of the focus error signal are set in accordance with the amount of a level change in the focus error signal, after which an acceleration operation of the focus actuator is started in response to a focus jump instruction to shift the focus position of read light for a focus jump, the acceleration operation is stopped in accordance with zero-crossing detection, a deceleration operation of the focus actuator is started thereafter and is stopped in accordance with zero-crossing detection, so that the operation returns to the focus servo operation.

Focus control apparatus for multilayer optical recording medium

A focus jump control apparatus of a player for playing a multilayer recording disc surely achieves a focus jump. This apparatus includes: a focusing servo loop for allowing a focal point to trace a recording surface in accordance with a focusing error signal by using a focusing actuator to displace the focal point of read light to a disc in the optical axial direction; and a tracking servo loop for allowing the focal point to trace disc tracks. A loop opening/closing control unit opens/closes focusing/tracking servo loops in response to an instruction and closes the focusing servo loop when the movement of the focal point from one of the recording surfaces to the other. During the movement of the read light focal point, the closing state of the tracking servo loop is maintained. Jump driving means generates a drive signal of the actuator to move the focal point from one of the recording surfaces to the other based on the error signal under the opening/closing control of the focusing/tracking servo loops.

Focus jump control apparatus of a player for multilayer recording disc

A carriage controller for a multi-layer disc which is capable of performing a stable carriage control during reproduction of a multi-layer disc of the opposite recording scheme. A tracking error signal is relayed by an equalizer, and a carriage motor is driven in accordance with an output signal of the equalizer. An information reading direction on a layer of a disc on which a pickup reads information is detected, and an equalizer characteristic is set in the equalizer in accordance with the detection result.

Carriage controller for multi-layer disc

Apparatus and method for focus control are devised to cope with a fluctuation of an optimum gain of a focus servo loop due to a difference between light reflectance of recording surfaces or the like and to allow an optimum focal position of read light to preferably trace a target recording surface. The focus control apparatus of the invention includes: reading device for generating a read signal of a recording medium 1; a focus servo loop for allowing an optimum converging position of the read light to trace the target recording surface in accordance with a focus error signal FE by using a focusing actuator to displace the optimum converging position of the read light in the optical axial direction; a level detecting unit of the read signal; a level detecting unit of an error signal FE; amplifiers and of a read signal RF and the error signal FE; and a control unit for driving the actuator so as to allow the optimum converging position of the read light to approach the recording surface in the set-up mode and for controlling gains of the amplifiers so that a detection level by the detecting unit in the set-up mode reaches a predetermined level and a detection level by a detecting unit reaches a predetermined level.

Apparatus and method for focus control of read light irradiated on a

An unbalanced waveform of a tracking error signal is automatically corrected within a short period of time. A peak value and a bottom value of a tracking error signal are obtained by a peak-hold circuit and a bottom-hold circuit, respectively. Based on the peak value and the bottom value, an amount of offset measured from a reference level and an amplitude of the tracking error signal are computed. An adjustment value is computed for correcting the unbalance between the peak value and the bottom value based on the amount of offset and the amplitude of the tracking error signal. The adjustment value is fed back to a tracking balance circuit so that the waveform of the unbalanced waveform of the tracking error signal is corrected.

Waveform controlling device for a tracking error signal

An optical information reproducing and/or recording system is provided with an optical system for irradiating a light beam to an information record surface of an information record medium and detecting the light beam reflected from the information record surface to output a light detection signal, an amplifying device for amplifying the light detection signal and generating a focus error signal which indicates an error of a focus point of the light beam with respect to the information record surface, and a feed back device for feeding back the focus error signal in the focus servo loop to change the focus point in accordance with a level of the focus error signal. An apparatus for controlling a bias amount of the focus error signal is provided with: a superimposing device for superimposing a disturbance signal to flutter the focus point with respect to the information record surface, onto the focus error signal; an error amount detecting device for detecting a focus error amount of the focus point, on the basis of the light detection signal outputted when the disturbance signal is superimposed; a parameter calculating device for calculating a gain parameter corresponding to an amplification factor of the amplifying device, and a sensitivity parameter corresponding to a detection sensitivity of the optical system; and a bias amount calculating device for calculating the bias amount.

Apparatus for controlling bias amount of focus error signal

An automatic gain control device includes: servo loop for performing servo control based on an error signal; gain control unit for controlling gain of the servo loop in accordance with gain control value; and storage unit for storing gain control values. The gain control unit starts gain control using the gain control value stored in the storage unit as default value with which the gain control is started, and stores the gain control value newly obtained by the gain control to the storage unit after the gain control is completed.

Device and method for automatically controlling a servo loop gain

Disclosed is a CD player that ensures a setup operation and reproduction of information even when a partially recorded CD-R is set therein. The CD player sequentially performs the setup operation, starting from the first setup position located at the innermost periphery of the CD, predetermined for the setup operation, until the setup operation is complete at any of n-th (n=2, 3, . . . ) setup positions lying outwardly of the first setup position. If the setup operation is not completed even at an n-th setup position located at the outermost periphery of the CD, the CD player performs the setup operation again at at least one setup position lying inwardly of the n-th setup position. Also disclosed is a CD player that can discriminate a partially recorded, additionally recordable CD-R, and can execute the reproduction control for the PRD. This CD player discriminates a set disk as an additionally recordable one when a mirror-finished portion is detected in the control to detect the lead-in area or when the lead-in area cannot be detected and the TOC information cannot be read.

Method and apparatus for executing a CD playback setup operation in a CD

Method and Apparatus for playing a CD are designed to allow playback of a partially recorded disk of CD-Rs (CD-Recordable) having the DRAW (direct read after write) capability. It is determined if a target disk is a partially recorded CD-R recording medium. When a reverse command to return to a predetermined address of the recording medium to execute playback is input, the absolute time for information being reproduced is detected and it is then determined if the absolute time is within a predetermined actual pause period. When the absolute time is determined to be within the actual pause period, the reverse command is canceled. It is therefore possible to properly operate a servo system within that recording area of the recording medium where information has already been recorded, thereby allowing a return to a predetermined address associated with the reverse command. This prevents the loss of control of the servo system. When the pickup position is in a lead-in area of the partially recorded CD-R recording medium, thus ensuring the proper reading control.

Method and apparatus for reproducing information from a partially

A CD player capable of detecting the recording end of a partially recorded CD-R (PRD) during playback. When an unrecorded area (URA) is detected, an address immediately before that of the URA is held and a setup is performed at the position of that detection. If the setup is unsuccessful, a setup is performed at a reference setup position, and when this setup operation is complete, playback starts from the held address position. When the playback from the position and detection of the URA are repeated a predetermined number of times, the held address position is discriminated as the recording end. According to a method of searching for the last piece of recorded information in the program area on a PRD, when reading failure occurs in a search, the pickup is moved back to a previous jump position to the occurrence of the reading failure. Then a search is conducted through a jump over tracks equal to or less in number than the number of tracks of a predetermined smallest amount of information from that jump position, and the last piece (e.g., song) is detected by a sub code acquired at a jump position immediately previous to the re-occurrence of reading failure. A CD player capable of ensuring reproduction of all the pieces of recorded information during playback of a PRD updates the last track number to the newly detected track number when detecting a next track number in an area following an area of a memorized last track number during playback of a PRD.

CD player capable of playing back partially recorded CD

A playing apparatus for a compact disc on which TOC information comprising at least first to third point data has repetitively been recorded in a lead-in area. A reading point by a pickup is moved in the lead-in area from the disc outer rim side in accordance with a TOC information reading command. When it is detected that the reading point was positioned to a recording track of third point data locating on the disc inner rim side in each of the TOC information, the reading point is jumped to the disc inner rim side by at least only two tracks. After that, the reading point is moved toward the disc outer rim side along the track, thereby reading the TOC information including the first, second, and third point data.

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Kawagoe, Japan

Alex Bradshaw