Device for correcting offset angle of pickup arm in tracking pickup apparatus

Claim 2

A pickup arm driving device in a linear tracking pickup apparatus, comprising: a pickup arm for tracing on a disc; support means for said pickup arm including a movable gimbal support including first means for supporting the pickup arm for vertical movement and second means for supporting the pickup arm for horizontal movement, said second means having a surface serving as a light-reflecting surface, and means mounting said gimbal support for linear movement; a motor designed so that its rotation speed and direction of rotation are determined by the value and the polarity of the voltage applied; a motive power transmitting means for converting the rotation force of said motor to a linear movement force and transmitting the latter force to said movable gimbal support; an offset angle detector for detecting a horizontal offset angle of the pickup arm, comprising said light-reflecting surface, a light-emitting source fixed to said mounting means to face said light-reflecting surface, and a photo-sensitive element fixed to said mounting means to face said light-reflecting surface; an offset signal generating circuit connected to said offset angle detector for generating an offset signal having a variable value and polarity corresponding to the variable magnitude and direction of the offset angle detected; and an amplifier for receiving, as an input thereof, said offset signal and for driving said motor, by the output of this amplifier, to rotate in a direction corresponding to the direction of movement of said movable gimbal support in which the offset angle decreases.

Claim 3

A pickup arm driving device according to claim 1, in which: said offset signal generating circuit comprises an electrode provided in contact with one side of said photo-sensitive element, a resistance body provided in contact with the other side of said photo-sensitive element, lead wires connected to both ends of said resistance body, and another lead wire connected to said electrode, whereby said output of said offset signal generating circuit is derived as a ratio of a resistance between one of the lead wires of said resistance body and the illuminated position of said photo-sensitive element to a resistance between the other lead wire of said resistance body and said illuminated position.

Claim 4

A pickup arm driving device according to claim 1, in which: the light rays from the light-emitting source are reflected at said light-reflecting surface as a broad light beam, and a change in the offset angle is derived as the amount of displacement of the center of this broad light beam.

Claim 5

A pickup arm driving device in a linear tracking pickup apparatus comprising: a pickup arm for tracking on a disc; support means for said pickup arm including a movable gimbal support with an inner first frame for supporting the pickup arm for vertical as well as horizontal movements and permitting the pickup arm to make linear travel radially of a disc in a horizontal direction and an outer second frame mounting said first frame and pickup arm for horizontal movement, and means for mounting said gimbal support for linear movement; a motor designed so that its rotation speed and direction of rotation are determined by the value and the polarity of the voltage applied; a motive power transmitting means for converting the rotation force of said motor to a linear movement force and transmitting the latter force to said movable gimbal support; an offset angle detector for detecting a horizontal offset angle for the pickup arm, including a light-reflecting surface formed on the surface of a portion of said inner first frame of said movable gimbal support to constitute a part of the surface thereof, a light-emitting source fixed to said outer second frame to face said light-reflecting surface and a photo-sensitive element fixed to the outer second frame to face said light-reflecting surface; an offset signal generating circuit connected to said offset angle detector for generating an offset signal having a variable value and polarity corresponding to the variable magnitude and direction of the offset angle detected; and an amplifier for receiving, as an input thereof, said offset signal and for driving said motor, by the output of said amplifier, to rotate in a direction corresponding to the direction of movement of said movable gimbal support in which the offset angle decreases.

Claim 6

A pickup arm driving device in a linear tracking pickup apparatus comprising: a pickup arm for tracking on a disc; support means for said pickup arm including a movable gimbal support with an inner first frame for supporting the pickup arm for vertical as well as horizontal movements and permitting the pickup arm to make linear travel radially of a disc in a horizontal direction and an outer second frame mounting said first frame and pickup arm for horizontal movement, and means for mounting said gimbal support for linear movement; a motor designed so that its rotation speed and direction of rotation are determined by the value and the polarity of the voltage applied; a motive power transmitting means for converting the rotation force of said motor to a linear movement force and transmitting the latter force to said movable gimbal support; an offset angle detector for detecting a horizontal offset angle for the pickup arm, including a light-reflecting surface formed on the surface of a portion of said inner first frame of said movable gimbal support to constitute a part of the surface thereof, a light-emitting source fixed to said outer second frame to face said light-reflecting surface and a photo-sensitive element fixed to the outer second frame to face said light-reflecting surface; an offset signal generating circuit connected to said offset angle detector for generating an offset signal having a variable value and polarity corresponding to the variable magnitude and direction of the offset angle detected; and an amplifier for receiving, as an input thereof, said offset signal and for driving said motor, by the output of said amplifier, to rotate in a direction corresponding to the direction of movement of said movable gimbal support in which the offset angle decreases.

Claim 7

A pickup arm driving device according to claim 4, in which: said light-emitting source is a light-emitting diode mounted on said outer second frame.