Optical device for reading-out a track carried by a moving data carrier

Claim 2

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said second direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said motor means being mechanically ganged with a velocity sensor; said feedback electric means including a velocity loop fed from said velocity sensor.

Claim 3

Optical device as claimed in claim 1, wherein said first ane second directions are both perpendicular to said axis.

Claim 4

Optical device as claimed in claim 1, wherein said motor means comprise an electrodynamic motor having a moving coil and means for generating a radial megnetic field around said coil; said velocity sensor comprising a further coil mechanically linked to said moving coil, and means for generating a further radial magnetic field around said further coil.

Claim 5

Optical device as claimed in claim 1, wherein said optical stigmatic means cmprise a microscope objective having a magnification substantially greater than unity.

Claim 6

Optical device as claimed in claim 1, wherein said photoelectric means comprise two photoelectric cells arranged in said detection plane symmetrically in relation to said image.

Claim 7

Optical device as claimed in claim 5, further comprising electrical means for supplying a voltage proportional to the sum of the voltages supplied from said photoelectric cells.

Claim 8

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said seCond direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said motor means driving a viscous damper associated with said optical stigmatic means.

Claim 9

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said seCond direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said motor means driving a viscous damper associated with said optical stigmatic means.

Claim 10

Optical device as claimed in claim 7, wherein said first and second directions are both perpendicular to said axis.

Claim 11

Optical device as claimed in claim 7, wherein said optical stigmatic means comprise a microscope objective having a magnification substantially greater than unity.

Claim 12

Optical device as claimed in claim 7, wherein said photoelectric means comprise two photoelectric cells arranged in said detection plane symmetrically in relation to said image.

Claim 13

Optical device as claimed in claim 10, further comprising electrical means for supplying a voltage proportional to the sum of the voltages supplied from said photoelectric cells.

Claim 14

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said second direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said motor means comprising a flexural electromechanical transducer of the bimorph plate type; said flexural electromechanical transducer comprising at least two piezoelectric elements having each one end clamped in said housing and said other end fastened to said optical stigmatic means.

Claim 15

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said second direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said motor means comprising a flexural electromechanical transducer of the bimorph plate type; said flexural electromechanical transducer comprising at least two piezoelectric elements having each one end clamped in said housing and said other end fastened to said optical stigmatic means.

Claim 16

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said second direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said photoelectric means comprising two photoelectric cells arranged in said detection plane symmetrically in relation to said image; said optical device further comprising a third photoelectric cell arranged in said detection plane; said third photoelectric cell having an elongated receiving face crossing said image.

Claim 17

Optical device for reading out a track positioned on the recorded face of a moving data carrier, said optical device comprising a housing, means for illuminating a portion of said track, optical stigmatic means for projecting onto a detection plane an image of the illuminated portion of said track, photoelectric means fixed to said housing and positioned in said detection plane for sensing the displacement of said image along a first direction crossing the axis of said track, motor means for displacing said optical stigmatic means in relation to said housing along a second direction; said second direction being parallel to said recorded face and arranged for crossing said axis, and feedback electric means for controlling said motor means in relation to the voltage supplied from said photoelectric means; said photoelectric means comprising two photoelectric cells arranged in said detection plane symmetrically in relation to said image; said optical device further comprising a third photoelectric cell arranged in said detection plane; said third photoelectric cell having an elongated receiving face crossing said image.