Pioneer Electronic Corporation

Yoshifumi Fujino

Kazuhiro Kiyoura

Koichiro Haraguchi

Takashi Suzuki

Seiji Kato

Hiroyuki Abe

Alex Bradshaw

Yoshimichi Nishio

Kazushige Kawana

Takeshi Matsumoto

Takehiro Takada

Mayumi Takahashi

Hideaki Yoshimura

Tomoko Miyagawa

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 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

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Kawagoe, Japan

Yoshifumi Fujino