Apparatus for reproducing information recorded on a disk

Claim 1

An apparatus for reproducing information recorded on a disk having a tracking servo device for read beam moving means for directing a read beam to a track on said disk, comprising: a velocity detector means for applying a first power product to a tracking servo read beam moving means upon turn-off of a tracking servo loop, and detecting a velocity of said moving means at the start of movement of said moving means based on an error signal of said tracking servo device; a standard signal generator means for generating a standard signal to said velocity detector means, a reference signal generator means for generating a reference signal corresponding to the velocity of said moving means based on the output of said velocity detector means; velocity control means for controlling the velocity of said moving means by comparing said error signal with said reference signal; correction means for applying to said moving means a force for substantially cancelling a force corresponding to a displacement of said moving means and developed in support means for supporting said moving means; a shaping circuit for shaping said error signal into a rectangular waveform; count means for pulse-counting the output from said shaping circuit to detect the number of tracks across which said moving means has moved to count a desired number of tracks; and means for closing said tracking servo loop approximately one half track before a target track to which said moving means is to be moved based on the content of said count means, and applying to said moving means a second power product which is opposite in polarity and equal in magnitude to said first power product to move said moving means across the predetermined number of tracks.

Claim 2

An apparatus for reproducing information recorded on a disk having a tracking servo device for read beam moving means for directing a read beam to a track on said disk, comprising: a velocity detector means for applying a first power product to a tracking servo read beam moving means upon turn-off of a tracking servo loop, and detecting a velocity of said moving means at the start of movement of said moving means based on an error signal of said tracking servo device; a standard signal generator means for generating a standard signal to said velocity detector means, a reference signal generator means for generating a reference signal corresponding to the velocity of said moving means based on the output of said velocity detector means; velocity control means for controlling the velocity of said moving means by comparing said error signal with said reference signal; correction means for applying to said moving means a force for substantially cancelling a force corresponding to a displacement of said moving means and developed in support means for supporting said moving means; a shaping circuit for shaping said error signal into a rectangular waveform; count means for pulse-counting the output from said shaping circuit to detect the number of tracks across which said moving means has moved to count a desired number of tracks; and means for closing said tracking servo loop approximately one half track before a target track to which said moving means is to be moved based on the content of said count means, and applying to said moving means a second power product which is opposite in polarity and equal in magnitude to said first power product to move said moving means across the predetermined number of tracks.

Claim 3

An apparatus for reproducing information recorded on a disk having a tracking servo device for read beam moving means for directing a read beam to a track on said disk, comprising: a velocity detector means for applying a first power product to a tracking servo read beam moving means upon turn-off of a tracking servo loop, and detecting a velocity of said moving means at the start of movement of said moving means based on an error signal of said tracking servo device; a standard signal generator means for generating a standard signal to said velocity detector means; a first memory means for holding a first velocity detected by said velocity detector means immediately after said moving means has started movement; a second memory means for holding a second velocity detected when said moving means has been moved across a predetermined number of tracks after the start of movement; a first reference signal generator means for generating a first reference signal corresponding to the content of said first memory when said moving means is several tracks before the target track; first velocity control means for comparing said error signal with said first reference signal to change the velocity of said moving means from the second velocity to the first velocity; a second reference signal generator means for generating a second reference signal corresponding to the content of said second memory; second velocity control means for comparing said error signal with said second reference signal to change the velocity of said moving means to the second velocity; correction means for applying to said moving means a force for substantially cancelling a force corresponding to a displacement of said moving means and developed in support means for supporting said moving means; a shaping circuit for shaping said error signal into a rectangular waveform; means for pulse-counting the output of said shaping circuit to detect the number of tracks across which said moving means has moved and counting the number of tracks which is equal to a desired number of tracks less several tracks; count means for counting the desired number of tracks; and means for closing said tracking servo loop approximately one half track before a target track to which said moving means is to be moved based on the content of said count means, and applying to said moving means a second power product which is opposite in polarity and equal in magnitude to said first power product to move said moving means across the predetermined number of tracks.

Claim 4

An apparatus for reproducing information recorded on a disk having a tracking servo device for read beam moving means for directing a read beam to a track on said disk, comprising: a velocity detector means for applying a first power product to a tracking servo read beam moving means upon turn-off of a tracking servo loop, and detecting a velocity of said moving means at the start of movement of said moving means based on an error signal of said tracking servo device; a standard signal generator means for generating a standard signal to said velocity detector means; a first memory means for holding a first velocity detected by said velocity detector means immediately after said moving means has started movement; a second memory means for holding a second velocity detected when said moving means has been moved across a predetermined number of tracks after the start of movement; a first reference signal generator means for generating a first reference signal corresponding to the content of said first memory when said moving means is several tracks before the target track; first velocity control means for comparing said error signal with said first reference signal to change the velocity of said moving means from the second velocity to the first velocity; a second reference signal generator means for generating a second reference signal corresponding to the content of said second memory; second velocity control means for comparing said error signal with said second reference signal to change the velocity of said moving means to the second velocity; correction means for applying to said moving means a force for substantially cancelling a force corresponding to a displacement of said moving means and developed in support means for supporting said moving means; a shaping circuit for shaping said error signal into a rectangular waveform; means for pulse-counting the output of said shaping circuit to detect the number of tracks across which said moving means has moved and counting the number of tracks which is equal to a desired number of tracks less several tracks; count means for counting the desired number of tracks; and means for closing said tracking servo loop approximately one half track before a target track to which said moving means is to be moved based on the content of said count means, and applying to said moving means a second power product which is opposite in polarity and equal in magnitude to said first power product to move said moving means across the predetermined number of tracks.