Victor Company of Japan, Limited

Yutaka Morita

Masatsugu Kitamura

Tsuyoshi Ono

Hideo Onoye

Yukihiro Kishima

Fumiaki Ohno

An output signal from a photodetector (3) responsive to light reflected at a phonograph record (2) is differentiated to produce positive and negative differential pulses (b.sub.1+, b.sub.1-), and the positive differential pulse (b.sub.1+) is retarded by a time length substantially equal to the time difference between the positive and negative differential pulses (b.sub.1+, b.sub.1-), while the negative differential pulse (b.sub.1-) is inverted to be a positive signal (d). The retarded signal (c) is added to the positive signal (d) so that the amplitude of the positive signal (d) becomes greater than before when the timing of the positive signal matches with the retarded signal (c). A resultant sum signal (e) produced in this way will be compared with a reference value (V.sub.TH1) to detect only unrecorded zones thereby accurately distinguishing unrecorded zones from recorded zones. The circuit arrangement therefore, comprises a differentiator (4), a circuit (D.sub.1, D.sub.2) for separating the positive differential pulse (b.sub.1+) from the negative differential pulse (b.sub.1-), a delay circuit (6), an inverting circuit (7), an adder (8), and a comparator (9).

Circuit arrangement and method for detecting unrecorded zones of a

A pickup arm is equipped with a photo sensor assembly for detecting non-recorded portions on a disk. The sensor is located in such a position that horizontal distance between the stylus tip and the detecting point of the sensor measured in the direction of the radius of the turntable is substantially constant throughout the possible rotational angle of the arm. The rotational angle of the arm is measured and is modified by a given angle corresponding to the above mentioned distance. When this distance deviates from a standard value on replacement of the same with another, the variation may be readily corrected by manipulating a potentiometer. Prior to performing an automatic playback, the disk is scanned by the sensor and signals indicative of the arm angles corresponding to the non-recorded portions are stored. After scanning, the arm is controlled by comparing the actual angle of the arm with the prestored angles, to place the stylus on a right position on the disk to perform automatic playback in accordance with programmed information.

Programmable automatic record player

A record disc playing apparatus comprises a horizontal drive motor for imparting a horizontal rotational force to a tone arm an address signal generating device for generating an address signal corresponding to a horizontal rotational angle position of the tone arm and a control device including a memory device for storing the magnitude of an inside force to be produced on the tone arm in correspondence with the horizontal rotational angle position of the tone arm. The address signal generating device supplies the generated address signal to the control device. The control device reads out the magnitude of the inside force from the memory device corresponding to the supplied address signal, produces a signal for cancelling the inside force at the rotational angle position of the tone arm corresponding to the read out magnitude of the inside force and supplies the same to the horizontal drive motor.

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Yokohama, Japan

Yutaka Morita