Nippon Gakki Seizo Kabushiki Kaisha

Shinji Aoshima

Norio Tomisawa

Shingo Kamiya

In picking up recorded data from a revolving optical disc by an optical reproduction system in an optical type disc reproduction device and detecting time data of Q subcode from the picked up data for performing operations such as searching a target position, the position control device according to this invention facilitates handling of data in cases such as computing time difference by converting detected present time data from a BCD code into a binary code by a BCD/binary conversion circuit and using the binary coded data. For searching a target position, time difference is detected by a time difference detection circuit on the basis of a difference between the binary coded present time data and target time data and a relative position of the optical reproduction system with respect to the optical disc is changed by a relative position change driver such that the time difference is reduced to zero.

Position control device for an optical reproduction system in an optical

A simplified clock-signal reproducing circuit for reproducing a clock signal from a repetitive pulse signal or a digital signal such as an EFM signal read from a compact disc as a data recording medium of the compact disc digital audio system is provided. A voltage-controlled oscillator generates a first repetition signal, and a second repetition signal is formed from the first repetition signal, the second repetition signal being the clock signal. The repetitive pulse signal is latched by a first latch in response to the clock signal, and a signal which is a delayed output of the first latch is latched by a second latch in response to the clock signal. A voltage representing a phase difference between a clock signal in the repetitive pulse signal and the clock signal generated by the voltage-controlled oscillator is generated in accordance with a first phase difference between the input and output signals of the first latch and a second phase difference between input and output signals of the second latch. This voltage is applied to the voltage-controlled oscillator to thereby control the frequency of the first repetition signal so that the first and second phase differences become equal to each other and that the clock signal generated by the voltage-controlled oscillator and the clock signal existing in the repetitive pulse signal coincide in phase with each other.

Growing community of inventors

Hamamatsu, Japan

Shinji Aoshima