Apparatus for information retrieval from an optically readable storage disc

Claim 1

An information selection device of a disc player which optically reads information of a plurality of pieces of music from a disc having a plurality of tracks where said information is optically recorded, the information of each of said plurality of pieces including piece number and index information consisting of information of the piece number of said each piece itself and information of a plurality of indexes existing within said each piece and each of said plurality of tracks having address information of said each track itself, said information selection device comprising: pickup means for radiating a light beam on said tracks of said disc, the radiated light beam being modulated and reflected when said light beam hits said tracks, beam detecting means for detecting said address information of the track hit by the radiated beam at present, from said reflected beam, moving means for moving said radiated beam to make said radiated beam cross said tracks of said disc, and signal processing means including: read means for reading said address information of the track hit by the radiated beam at present, detected by said beam detecting means, write means for writing the address information of a target track defined by a desired piece to be played and a desired index within said desired piece selected out of said plurality of pieces, first comparing means for comparing the address information of the track hit by the radiated beam at present, read by said read means, and the address information of said target track written in advance in said write means so that a control signal for reversing the moving direction of said radiated beam is generated and applied to said moving means each time it is determined that said radiated beam has passed said target track, a first register in which the address information of the track hit by the radiated beam is written when it is determined as a result of the comparison by said first comparing means that the address information of the track hit by the radiated beam is larger than the address information of the target track, a second register in which the address information of the track hit by the radiated beam is written when it is determined as a result of the comparison by said first comparing means that the address information of the track hit by the radiated beam is larger than the address information of the target track and second comparing means for comparing the address information written in said first register and the address information written in said second register; said second comparison means including means for generating a control sigtnal for decreasing the moving speed of the radiated beam from a first speed to a second speed when it is determined that the aboslute value of the difference between said address information written in said first register and said address informatiopn written in said second register is smaller than a first set value and that the radiated beam has passed the target track; said second comparison means including means for generating a control signal for decreasing the moving speed of the radiated beam from the second speed to a third speed when it is determined that the absolute value of the difference between said address information written in said first register and said address information written in said second register is smaller than a second set value and that the radiated beam has passed the target track; said second comparison means including means for generating a control signal for decreasing the moving speed of the radiated beam by steps until the absolute value of the difference between said address information written in said first register and said address information written in said second register becomes smaller than the n-th set value; and said second comparison means including means for thereafter generating a control signal for moving the radiated beam to the track corresponding to the address information written in said first register or said second register.