Pioneer Electronic Corporation

Pioneer Corporation

Pioneer Electronics Corporation

Hideyo Kamiyama

Akira Kawakami

Yasunari Kawahara

A track-jump controlling apparatus that controls track-jump operations over disks complying with various DVD data formats includes a quad photodetector having quadrants B to B , a DPDTE signal generator for generating DPD tracking error signals, a push-pull signal generator for generating push-pull signals, and a TZC signal generator having a selector switch for switching the path between the DPDTE signals and the push-pull signals and a comparator for generating TZC signals. In order to prevent failure to obtain proper TZC signals in a seek operation with respect to a DVD-RW, etc. involving passage over an unrecorded area during reproduction, for example, the selector switch is switched to the push-pull signal side to prevent track counting failure associated with the track-jump operation with respect to the DVD-RW.

Track-jump controlling apparatus and method

A laser beam is focused at positions on an optical axis of the optical pickup by a focusing device, corresponding to kinds of the discs which are different in thickness. The focusing device is moved along the optical axis. A photodetector is provided for receiving a laser beam reflected from the disc and for producing a focus error signal. A detector is provided for detecting the difference between the focus error signals, caused by the difference in thickness of the discs and the difference in focal point of the laser beam, thereby discriminating the kind of the disc.

System for discriminating optical discs

A feed velocity control apparatus of a disc player which can execute a stable velocity control of an information reading point by reducing influences by scratches formed on the recording surface of a recording disc, noises, or the like. A velocity signal corresponding to a transporting velocity of the information reading point at the present time point for the recording disc is obtained based on a tracking error signal. At the time of the track jumping operation, when the velocity signal lies within a predetermined velocity range, the information reading point is transferred in accordance with a velocity error signal corresponding to a difference between the velocity signal and a predetermined velocity. When the velocity signal is out of the predetermined velocity range, the information reading point is transferred in accordance with a low band component of the velocity error signal in place of the velocity error signal.

Feed velocity control apparatus for controlling the movement of information reading point of disc player

A servo device for controlling a reading operation of a pickup in a recording medium player, which generates a servo error signal indicative of an amount of deviation of a position at which the pickup of the recording medium player is reading for playing a recording medium. The servo device detects a blemish at a reading point focused by the pickup on the recording medium to generate a blemish detecting signal when a blemish is detected, and generates a servo hold signal based on a low frequency component of the servo error signal. The servo hold signal includes, immediately after the generation of the blemish detecting signal, a signal of opposite polarity to the polarity of the servo error signal immediately before generation of the blemish detecting signal. Further, the servo device controls the reading operation of the pickup in accordance with the servo hold signal in place of the servo driving signal during the time that the blemish detecting signal is generated.

Servo device for recording medium player

Tracking pull-in circuit for reducing effect by a defect in a tracking servo loop

The upper envelop signal generating unit detects the upper envelop of the detection signal to generate the upper envelop signal corresponding to the detected upper envelop, and the lower envelop signal generating unit detects the lower envelop of the detection signal to generate the lower envelop signal corresponding to the detected lower envelop. The slice signal generating unit divides the voltage difference of the upper envelop signal and the lower envelop signal using a predetermined division ratio to generate the slice signal. The averaging unit averages the slice signal to produce the average signal. The defect detecting unit compares the average signal and the upper envelop signal to produce the defect detection signal indicating the period in which the voltage of the upper envelop signal is lower than the voltage of the average signal. As a result, a very short defect like a wedge-shape defect can be reliably detected.

Defect detector and information reproduction apparatus employing the same

A defect detection apparatus has a simple constitution and performs accurate defect detection while clearly differentiating between defect detection and tracking error detection. The defect detection apparatus includes a photodetector having a light-receiving area for receiving a return light beam from a recording medium irradiated with a light beam. A defect on the recording medium is detected based on an output from the photodetector. The defect detection apparatus according to the present invention comprises signal generation means for generating on the basis of an output from the photodetector at least two phase detection signals having phases which vary in a manner complementary to each other according to a deviation of the light beam from a track of the recording medium, adding means for adding up absolute value of the phase detection signal to generate a sum total signal having a value corresponding to a result of the addition, and discrimination means for comparing the value of the sum total signal with a predetermined reference value so as to generate a defect detection signal based on a result of the comparison.

Defect detection apparatus for detecting defects on a recording medium

A focus servo pull-in apparatus which discriminates the type of an optical disk and executes focus servo from the optimal position according to the disk type. This focus servo pull-in apparatus performs a focus servo pull-in control operation at the time of reproducing information from one of at least two types of recording media with different distances from surfaces of the recording media to information recording planes where information is recorded. The apparatus comprises a light-emitting unit for irradiating a light beam on an information recording surface of a recording medium in use, a light-receiving unit for receiving reflected light of the light beam from the information recording surface, a moving unit for moving an objective lens for directing the light beam to a focus, in a direction parallel to an optical axis of the light beam, a discrimination unit for discriminating a type of the recording medium in use and outputting a discrimination signal, and a control unit for performing different pull-in controls in accordance with the discrimination signal.

Focus servo pull-in apparatus for use in a compatible disk player

A disk discrimination apparatus for use in an optical disk reproducing apparatus detects a tracking error signal, discriminates between disks, and prevents reproduction of a disk which does not correspond to the reproducing apparatus. In the disk discrimination apparatus, when a second type disk, having a track pitch which is smaller than that of a first type disk, is played by the optical disk reproducing apparatus, a discriminator detects that the disk is not a first type disk based on an output signal of a tracking error signal generating circuit. The discriminator performs a discrimination operation by comparing the signal level of a tracking error signal with a predetermined reference value. In another embodiment, the discriminator includes a counter for counting the number of zero-crossings of the tracking error signal, and performs the disk discrimination using a count value produced by the counter.

Disk discrimination apparatus for an optical disk reproducing apparatus

An information reproducing apparatus which enables regulation of sound volume levels of signals reproduced from a multiple-audio recording medium in which one of a plurality of audio information signals may be reproduced in conjunction with video information. The multiple-audio signals are recorded on a surface of a video disk, along with the video information. A code signal indicative of presence of multiple-audio information also is recorded, and is detected by code reading circuitry in the apparatus. Operation of changeover circuitry is controlled in accordance with the presence or absence of the code signal, and also in accordance with operation of a microphone in a microphone mixing mode.

Growing community of inventors

Tokorozawa, Japan

Hideyo Kamiyama