Abstract: A disc reproducing device has a lock pin for positioning a small-diameter disc inserted into the device in a reproducing position by being loaded by a spring with a force that rotates it about a horizontal shaft, a lock plate for locking the lock pin in a protruding state in the normal state, and a disc detecting lever, locked by being pressed by the outer periphery of a large-diameter disc inserted, for moving the lock plate horizontally with its front end so as to lock and unlock the lock pin. The lock pin in its unlocked state is rotated by being pressed by the large-diameter disc, and, after the largest dimensioned portion of the large-diameter disc passes over the disc detecting lever, the lock plate returns to its original position to lock the lock pin in its falling-down state. With this construction, either an 8-cm-diameter disc or a 12-cm-diameter disc can be reproduced simply by inserting the disc into the device without using an adopter dedicated to an 8-cm-diameter disc.

Abstract: For reducing the number of components used and thereby attaining the reduction of cost and size while ensuring the same disk detecting performance as in the prior art, both light emitting function and light receiving function inherent in an optical pickup are utilized to constitute a disk detecting switch. Only the light emitting function of the optical pickup may be combined with a light receiving element, or only the light receiving function of the optical pickup may be combined with a light emitting element, to constitute a disk detecting switch.

Abstract: A disc reproducing device has a lock pin for positioning a small-diameter disc inserted into the device in a reproducing position by being loaded by a spring with a force that rotates it about a horizontal shaft, a lock plate for locking the lock pin in a protruding state in the normal state, and a disc detecting lever, locked by being pressed by the outer periphery of a large-diameter disc inserted, for moving the lock plate horizontally with its front end so as to lock and unlock the lock pin. The lock pin in its unlocked state is rotated by being pressed by the large-diameter disc, and, after the largest dimensioned portion of the large-diameter disc passes over the disc detecting lever, the lock plate returns to its original position to lock the lock pin in its falling-down state. With this construction, either an 8-cm-diameter disc or a 12-cm-diameter disc can be reproduced simply by inserting the disc into the device without using an adopter dedicated to an 8-cm-diameter disc.

Abstract: A printed circuit board has a product board region where electronic components are mounted. The printed circuit board further has a positioning region where an element contour representing a certain mechanism element, an insulated substrate or the like is formed by a perforation line, a V-cut line or the like so as to be separated from the other portion of the positioning region along the line for another use. Instead of the foregoing element contour, a small printed circuit pattern with or without a small electronic component may be separably formed in the positioning region.

Abstract: For reducing the number of components used and thereby attaining the reduction of cost and size while ensuring the same disk detecting performance as in the prior art, both light emitting function and light receiving function inherent in an optical pickup are utilized to constitute a disk detecting switch. Only the light emitting function of the optical pickup may be combined with a light receiving element, or only the light receiving function of the optical pickup may be combined with a light emitting element, to constitute a disk detecting switch.

Abstract: In an optical pick-up position detector, an optical pick-up is movable by a motor in radial directions of an optical disk for detecting signals on the optical disk. A driver applies a driving voltage to terminals of the motor for forward or reverse rotation of the motor according to a control signal from a controller. The controller has an input terminal connected to a power supply via a resistor and further has a control terminal for outputting the control signal to the driver according to an electric potential at the input terminal of the controller. A switch is disposed between the input terminal of the controller and one of the terminals of the motor. The switch changes its operating state when the optical pick-up moves to exceed a reference position in a radially inward or outward direction with respect to the optical disk. The switch may be connected to the input terminal of the controller via a diode.