1. Field of the Invention
The present invention relates to a disc playing system, and more particularly to a disc playing system which stores a plurality of discs and capable of continuous playing of discs in order which discs are arbitrarily selected from the stored discs.
2. Description of Background Information
As an example of the disc playing system of this type, a disc displaying system is described in Japanese Patent Application No. 56-67396corresponding to U.S. patent application Ser. No. 373,123 filed May 2, 1982. In this disc playing system, a plurality of discs are stored in a disc storing part and juxtaposed at a predetermined space. A disc playing means is provided to be slidable along the direction of the arrangement of the discs, and a detection means is provided for detecting the position of the disc playing means relative to each storing slot of the disc storing part. The disc playing means is translated along the direction of the disc arrangement and stop position is controlled in accordance with the output signal of the light sensor so that the disc playing means stops at the position of a selected disc. The playing of the selected disc is parformed after the disc is moved from the disc storing part to the playing position by means of a disc transportation means.
A disc presence or absence sensor is provided in the middle of the route of the movement of the disc from the disc storing part to the playing position and the detection of the presence or absence of a disc in a selected disc storing slot is performed in such a manner as to detect whether or not the passing of a disc is sensed within a predetermined time period after the start of the operation of the disc transportation means. If it is detected that no disc is present in the selected disc storing slot, then the number of the slot is memorized in the memory means. Thus, further designation of the disc storing slot having no disc is prevented and as a result the discs are played in sequence very smoothly.
Since this conventional disc playing system is constructed in this manner, there is an advantage that the disc storing slot with no disc is no selected twice. However, at the time of first selection of such a disc storing slot, the playing means is moved to the position of the selected slot and the disc translation means is actuated until the absence of the disc is sensed. Thus, there is a drawback that the electricl engergy is consumed by the movement of the playing means and the disc transportation means and also a time period is consumed by the above process.
Further, in the case of the disc playing system of Japanese Patent application No. 57-45276 proposed by the present applicant, a scaning is effected through all of the disc storing slots at the time of throw-in of the power current and the numbers of the vacant disc storing slot are memorized. However, also in this type of disc playing system, there is the same problem that the disc transportation means is moved to the position of each disc storing slot and the output signal of the disc presence sensor is observed each time. Thus a long time period is required before the selection of the disc becomes possible after the throw-in of the power current.