Sharp Kabushiki Kaisha Corporation

Daiji Yamane

Nobuyuki Horie

Noriaki Sakamoto

Kunio Kojima

Toshihisa Deguchi

Toshihiro Yamanaka

Yoshiki Nishioka

Yoshio Yuki

Teruki Sugiura

Aisaku Taguchi

A test mode switching system includes a register for storing test signal data and for outputting the test signal data to a self testing circuit for checking whether or not the LSI operates correctly. A memory stores a test inhibiting signal and a test allowing signal received from a CPU through the control signal terminal of the LSI. The register is enabled to output test signals depending on the condition of the output of the memory whereby the LSI can operate either under a normal operation mode or under a test mode.

Test mode switching system for LSI

A motor stop control device for stopping a motor rapidly. The motor control includes a pulse generator for generating a pulse signal having a pulse width which is in relation to the speed of the motor, a CPU, and a drive for driving the motor. When a motor stop command signal is produced when the motor being rotated forward, CPU operates the drive to produce a counter drive torque, and, at the same time, CPU starts to compare the pulse width of the present pulse signal with that of the previous pulse signal, and produces a signal when the pulse width of the present pulse signal becomes shorter than that of the previous cycle. When the signal is produced, the drive stops to produces the counter drive torque.

Motor stop control device

A transducer access control system for use in a disk recording/reproducing apparatus for moving a transducer a required distance from its present position over a disk in the radial direction thereof, includes a linear motor for driving the transducer, a circuit for generating a distance signal indicative of the required distance for moving the transducer, and a calculator for calculating a half distance which is a half of the required distance. To move the transducer for the required distance D, the linear motor is operated at the velocity controlled in accordance with a reference velocity signal produced from a reference velocity generator. The reference velocity is determined such that, the reference velocity is maintained at a predetermined value during the movement of the transducer in the first half of the required distance, and gradually decreases during the movement of the transducer in the second half of the required distance.

Transducer access control system

An optical disk apparatus comprises a light emission detection circuit which converts a light emission from a light source into an electric signal and releases it as a light emission signal, a photo detector which releases an output signal upon reception of a reflected light from a disk and/or stray lights, a correction signal generating circut which adjusts a prescribed gain in accordance with the amount of stray light, and generates a correction signal by attenuating the light emission signal based on this gain, a subtracter in which the correction signal is subtracted from the output signal of the photo detector, and disk discharging means for discharging the disk from the optical disk apparatus, when the disk is present in the optical disk apparatus during the adjustment of the above-mentioned gain. The optical disk apparatus is arranged such that an optimum gain may be obtained even when the disk is present inside the optical disk apparatus, since the disk is discharged from the optical disk apparatus by the disk discharging means during the adjustment of the gain. Thereby an accurate tracking error signal and focus error signal may be otained by correcting the output signal of the photo detector.

Servo control gain adjustment for an optical disk apparatus

Method and device of beam control for stabilizing the laser beam output is controlled by adjusting the driving current of laser beam source. To adjust the driving current output light from laser beam source is detected by a photo detector. This output light has the same specific polarization components the light used to record or read from a magnetic optical disc. The detected light is converted into an electric signal corresponding to the light intensity. This electric signal is compared with a specified reference level to determine the change in the output level of the laser source due to a change in the ambient temperature.

Beam control device utilizing beam having a specific direction of

An apparatus for reading an optical disk having tracks extending tangentially includes a driving device for moving at least one light spot. A signal which indicates a deviation of the light spot from one of the tracks and a second circuit produces acceleration and deceleration signals. The driving device is controlled to accomplish a track jump of the light spot in accordance with the acceleration and deceleration signals. The second circuit produces the acceleration signal when a track jump is to be initiated and produces the deceleration signal when the ratio of the level of the tracking error signal to the peak value of the tracking error signal becomes equal to a predetermined value.

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Yamatokoriyama, Japan

Daiji Yamane