1. Field of the Invention
The present invention relates to a disk playback apparatus provided with a centering mechanism for accurately and consistently positioning a disk, which has been inserted therein, at a clamp location on a turntable.
2. Description of the Related Art
Recently, there has been provided a compact disk referred to as a disk hereinafter in which analog sound are converted into digital signals and then pits corresponding to the digital signals are formed in a recording layer thereof. With such a disk, analog sound may be optically reproduced by a laser beam emitted from an optical head of the CD player. Also, in comparison with a conventional LP record, the disk is extremely superior in sound quality and operational properties. Accordingly, the disk has been widely used together with the CD player. In particular, CD players have been developed for automotive use. When a disk having a diameter of 12 cm for playback of music is inserted into a disk insertion opening, the disk is loaded toward a predetermined position (the substantially central position of the CD player) by a loading mechanism. When the disk is brought into contact with a stop portion provided within the CD player, the loading operation is stopped to position the disk in place. In this position, the disk is fixed onto a turntable by means of a clamper arm. The disk on the turntable is rotated by a spindle motor, and the music recorded in the disk is reproduced by a readout head.
On the other hand, a disk having a much smaller diameter of 8 cm has been recently developed. However, if it is desired to insert such a disk into the insertion opening of the conventional CD player, the operator must pay special attention to the operation because the width of the insertion opening is too large.
Also, in a conventional CD player, since the stop portion for stopping the inserted disk at the clamp position is provided for positioning the large diameter disk, when the smaller disk is transferred into contact with the stop portion, the smaller disk would be advanced beyond the clamp position.
Accordingly, there has been proposed a centering system for guiding the small diameter disk to the center of the disk insertion opening. In this case, a disk guide plate has been provided below the clamper arm for guiding the small disk to the clamp position.
However, if such a centering mechanism is provided at the disk insertion opening, the overall mechanism of the player becomes complicated. Also, in a conventional disk player, after the centering operation of the disk has been performed at the disk insertion opening, the disk is transferred to the clamp position. As a result, there is a possibility that the disk would be likely to be displaced or offset during clamping so that it would be difficult to accurately clamp the disk at the desired position. Furthermore, when a larger disk is inserted into the player, the disk must be brought into contact with the centering mechanism, and the operator must push the disk to open the centering mechanism. This can be cumbersome to the operator.