Pioneer Electronic Corporation

Koichiro Haraguchi

Kazuhiro Kiyoura

Seiji Kato

Hiroyuki Abe

Alex Bradshaw

Yoshio Aoyagi

Yoshiya Nonaka

Yoshifumi Fujino

Kiyoshi Furukawa

Takeshi Matsumoto

Chiaki Hirano

Takashi Suzuki

Kazushige Kawana

Takehiro Takada

Yoshimichi Nishio

Hideaki Yoshimura

Tomoko Miyagawa

Mayumi Takahashi

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 automatic gain control device includes: reading unit for reading information signal from a recording medium; servo loop including servo control unit for controlling position of the reading unit with respect to the recording medium; mixing unit for mixing a disturbance signal into the servo loop; gain control unit detecting gain of the servo loop in accordance with level of the disturbance signal and varying the gain of the servo loop; and level detecting unit for discriminating whether level of the information signal read by the reading unit is higher than a predetermined level or not, wherein the mixing unit mixes the disturbance signal into the servo loop when the level of the information signal is higher than the predetermined level.

Gain control device for servo control

An automatic gain control apparatus for an optical disc player is equipped in a servo loop to perform a servo control by use of an error signal in the optical disc player. The apparatus is provided with: a gain control device for controlling a gain of the servo loop to have a controlled gain value corresponding to a signal level of the error signal in one series of automatic gain controlling operation; a memory for storing the controlled gain value as a previously controlled gain value in said one series of automatic gain controlling operation; a comparison device for comparing the previously controlled gain value, which is stored in the memory, with a presently controlled gain value of the gain of the servo loop, which is presently controlled by the gain control device in another series of automatic gain controlling operation after said one series of automatic gain controlling operation; and a controller for instructing the gain control device to control the gain of the servo loop again if a difference between the previously controlled gain value and the presently controlled gain value is not less than a predetermined value according to a comparison result of the comparison device in said another series of automatic gain controlling operation.

Automatic gain control apparatus for optical disc player

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

Koichiro Haraguchi