Optical disc reproducing apparatus

Claim 2

In an apparatus for reproducing an information signal recorded on an optical disc along spiral or concentric tracks, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical disc as a light spot, means for rotating the optical disc at a given speed, means for receiving light from said disc modulated in accordance with the information signal recorded on said disc to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot in a radial direction of the disc to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot in a radial direction of said disc being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal to cause said light spot to trace the same track.

Claim 3

An apparatus according to claim 1, wherein said means for detecting the direction and speed of the light spot comprises, means for detecting an eccentricity component of a displacement of the light spot, and means for detecting a velocity component from the eccentricity component.

Claim 4

An apparatus according to claim 2, wherein said eccentricity component detecting means comprises means for detecting a signal proportional to the tracking error signal.

Claim 5

An apparatus according to claim 3, wherein said signal detecting means comprises a resistor through which the tracking error signal is passed.

Claim 6

In an apparatus for reproducing an information signal recorded on an optical disc along spiral or concentric tracks, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical disc as a light spot, means for rotating the optical disc at a given speed, means for receiving light from said disc modulated in accordance with the information signal recorded on said disc to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot in a radial direction of the disc to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot in a radial direction of said disc being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal, said means for detecting comprising means for detecting an eccentricity component of a displacement of the light spot and means for detecting a velocity component from the eccentricity component, said means for detecting the velocity component including a first sample and hold circuit coupled to sample and hold said eccentricity component and provide an output thereof, a differentiating circuit coupled to differentiate the output of said first sample and hold circuit to provide a differentiated output, a second sample and hold circuit coupled to sample and hold said differentiated output as said velocity component, and a sampling pulse generating circuit coupled to cause sampling pulses to be supplied to said first and second sample and hold circuits to produce sampling and holding of said eccentricity component and said differentiated output; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal to cause said light spot to trace the same track.

Claim 7

In an apparatus for reproducing an information signal recorded on an optical disc along spiral or concentric tracks, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical disc as a light spot, means for rotating the optical disc at a given speed, means for receiving light from said disc modulated in accordance with the information signal recorded on said disc to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot in a radial direction of the disc to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot in a radial direction of said disc being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal, said means for detecting comprising means for detecting an eccentricity component of a displacement of the light spot and means for detecting a velocity component from the eccentricity component, said means for detecting the velocity component including a first sample and hold circuit coupled to sample and hold said eccentricity component and provide an output thereof, a differentiating circuit coupled to differentiate the output of said first sample and hold circuit to provide a differentiated output, a second sample and hold circuit coupled to sample and hold said differentiated output as said velocity component, and a sampling pulse generating circuit coupled to cause sampling pulses to be supplied to said first and second sample and hold circuits to produce sampling and holding of said eccentricity component and said differentiated output; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal to cause said light spot to trace the same track.

Claim 8

An apparatus according to claim 5, wherein said sampling pulse generating circuit comprises, an oscillator for generating a signal having a frequency which is sufficiently higher than a frequency of the eccentricity component; a first pulse generator triggered by the output signal from the oscillator to produce sampling pulses to be supplied to the first sample and hold circuit; a phase shifter for delaying the output signal from the oscillator by a given phase to produce a delayed signal; and a second sampling pulse generator triggered by the delayed signal from the phase shifter to produce sampling pulses to be supplied to the second sample and hold circuit.

Claim 9

In an apparatus for reproducing an information signal recorded on an optical disc along spiral or concentric tracks, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical disc as a light spot, means for rotating the optical disc at a given speed, means for receiving light from said disc modulated in accordance with the information signal recorded on said disc to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot in a radial direction of the disc to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot in a radial direction of said disc being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal and cause said light spot to trace the same track, said means for modifying said return signal including a pulse level modulator coupled to modulate the level of said return signal in accordance with said detected direction and speed of said light spot.

Claim 10

In an apparatus for reproducing an information signal recorded on an optical disc along spiral or concentric tracks, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical disc as a light spot, means for rotating the optical disc at a given speed, means for receiving light from said disc modulated in accordance with the information signal recorded on said disc to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot in a radial direction of the disc to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot in a radial direction of said disc being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal and cause said light spot to trace the same track, said means for modifying said return signal including a pulse level modulator coupled to modulate the level of said return signal in accordance with said detected direction and speed of said light spot.

Claim 12

An apparatus according to claim 8, wherein said optical disc comprises a video signal as said information signal and said separating circuit separates a frame synchronizing pulse in a reproduced video signal.

Claim 13

In an apparatus for reproducing an information signal recorded in tracks on an optical medium, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical medium as a light spot, means for moving the optical medium with respect to said spot, means for receiving light from said optical medium modulated in accordance with the information signal to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot relative to a track to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal to cause said light spot to trace the same track.

Claim 14

In an apparatus for reproducing an information signal recorded in tracks on an optical medium, wherein said apparatus comprises means for emitting a light beam, means for focusing the light beam onto the optical medium as a light spot, means for moving the optical medium with respect to said spot, means for receiving light from said optical medium modulated in accordance with the information signal to produce a reproduced signal, means responsive to said spot position with respect to a track for detecting a tracking error and producing a tracking error signal, means responsive to said tracking error signal for moving the light spot relative to a track to control said tracking error, and means for producing a return signal representing the amount of movement necessary to cause said light spot to trace the same track, said means for moving said light spot being responsive to said return signal to move said light spot so that it returns to trace said same track, the improvement in said apparatus comprising: means for detecting the direction and speed of movement of said light spot on said disc in response to said tracking error signal; and means responsive to said detected direction and speed of said light spot movement for modifying said return signal to cause said light spot to trace the same track.