Tracking control system of an optical pick-up

Claim 1

A tracking control system for controlling a positional relationship between an optical pick-up and a rotating disc having formed thereon a recording track, comprising: detecting means connected to said optical pick-up for detecting an error in tracking said recording track and producing a tracking error signal; filtering means connected to receive said tracking error signal and to pass a predetermined band of frequency thereof and thereby produce an output; phase compensating means connected to receive said tracking error signal and to compensate for the phase of said tracking error signal and produce an output; comparator means connected to receive said tracking error signal and to produce an output signal indicative of whether or not said tracking error signal is above zero level; pulse generating means connected to receive the output signal from said comparator means and to produce a drive pulse of a polarity corresponding to the direction of a desired movement of said optical pick-up relative to the disc; adding means receiving said pulses; a first switch means connected between said filtering means and said adding means; a second switch means connected between said phase compensating means and said adding means; and control means operative during a first control mode to sum the output of said phase compensating means and the output of said filtering means to thereby produce a first feed-back signal supplied to said optical pick-up to cause said optical pick-up to be aligned with said recording track, and operative during a second control mode to inhibit the output from said phase compensating means and to produce an acceleration pulse having a polarity corresponding to the direction of a desired movement of said optical pick-up with respect to the disc, and to thereafter produce a deceleration pulse opposite in polarity to said acceleration pulse in response to an output from said comparator means indicating that said tracking error signal has crossed zero level, wherein the output from said filtering means, said acceleration pulse, and said deceleration pulse are added to define a second feed-back signal supplied to said optical pick-up to cause it to be aligned with another recording track, said control means being connected to both of said first and second switch means to control their operating conditions.

Claim 19

A method of operating an optical disc system in which a disc with radially spaced tracks rotates relative to an optical pick-up comprising: detecting errors in the tracking of a selected track on the disc by the optical pick-up and producing a tracking error signal indicative of detected errors; and selectively operating the system in one of (i) a normal tracking mode, to generate a first control signal as a function of the tracking error signal for application to the pick-up to maintain it in alignment with the selected track, and (ii) a track jump mode, to generate a track jump signal related to the spacing between the selected track and another track and to produce a second control signal which is a function both of said tracking error signal and of said track jump signal for application to the pick-up to move it from said selected track to said another track, said second control signal being the algebraic sum of said tracking error signal and said track jump signal.

Claim 20

A method of operating an optical disc system in which a disc with radially spaced tracks rotates relative to an optical pick-up comprising: detecting errors in the tracking of a selected track on the disc by the optical pick-up and producing a tracking error signal indicative of detected errors; and selectively operating the system in one of (i) a normal tracking mode, to generate a first control signal as a function of the tracking error signal for application to the pick-up to maintain it in alignment with the selected track, and (ii) a track jump mode, to generate a track jump signal related to the spacing between the selected track and another track and to produce a second control signal which is a function both of said tracking error signal and of said track jump signal for application to the pick-up to move it from said selected track to said another track, said second control signal being the algebraic sum of said tracking error signal and said track jump signal.