Patent US2222609A successfully refreshed from Google Patents.
Patent US3974327A successfully refreshed from Google Patents.
US3974327A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Autofocus circuit for a videodisc playback device
Assignee: US Philips Corp
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Filing: 1975-03-03
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Granted: 1976-08-10
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Expires: 1995-03-03
Abstract
Abstract An apparatus is described for reading a flat reflecting record carrier on which information is stored in an optically readable structure, which apparatus, inter alia, includes an objective system for focussing a read beam on the plane of the information structure and a focus detection system which is coupled to an electronic circuit for deriving a control signal for controlling the position of the objective system relative to the plane of the information structure. The electronic circuit is equipped so that the control signal ensures that during locking-in the objective system is moved with a low preferably constant, speed towards the record carrier until the required position is substantially attained, after which the objective system is subject to a high acceleration in the opposite direction.
Inventors
- 👤 Ate Van Dijk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:04
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08511; G02; G02B; G02B27/00; G02B27/40; G11B7/09; G11B7/0908; G11B7/0917; G11B2007/0924
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
431 words
An apparatus for reading a flat reflecting record carrier on which information is stored in an optically readable structure, comprising a radiation source means for supplying a read beam; an objective system for focussing the read beam on the plane of the information structure; a radiataion-sensitive signal detection system for converting the read beam after having been modulated by the information structure into an electrical signal; and an objective position control system, the objective position control system comprising focus detection means for providing an electrical focussing signal corresponding to the direction and magnitude of the deviation of the objective system from a predetermined distance from the information structure of the record carrier at which predetermined distance the read beam is focussed on the information structure, a signal controlled objective drive means for advancing the objective system toward the record carrier information plane from a rest position at a distance exceeding said predetermined distance to a position closer than said predetermined distance and for moving said objective system away from said record carrier, first signal controlled electrical means for selectively connecting said focussing signal to said objective drive means in response to a first timing signal, second signal controlled electrical means connecting said focus detection means to said drive means through said frist signal controlled electrical means for selectively amplifying the focussing signals that advance and move back the objective system in response to a second timing signal and for selectively amplifying and amplitude limiting only those focussing signals that advance the objective system in response to an absence of said second timing, signal, third signal controlled electrical means responsive to an absence of said second timing signal for selectively adding to said focussing signals an electrical bias signal that tends to advance the objective system at a substantially uniform rate toward the record carrier and for providing velocity feedback to said objective drive means through said first signal controlled electrical means, thereby advancing said objective system at a substantially fixed velocity in response to an absence of said second timing signal, and clock means for providing said first timing signal for said first signal controlled electrical means and for concurrently providing an absence of said second timing signal for said second and third signal controlled electrical means to advance the objective system from said rest position toward said record carrier at a substantially fixed velocity and for providing said second timing signal at a time after the initiation of the first timing signal calculated to be such that the objective system is closer to the record carrier than said predetermined distance
Claim 2
Independent Claim
431 words
An apparatus for reading a flat reflecting record carrier on which information is stored in an optically readable structure, comprising a radiation source means for supplying a read beam; an objective system for focussing the read beam on the plane of the information structure; a radiataion-sensitive signal detection system for converting the read beam after having been modulated by the information structure into an electrical signal; and an objective position control system, the objective position control system comprising focus detection means for providing an electrical focussing signal corresponding to the direction and magnitude of the deviation of the objective system from a predetermined distance from the information structure of the record carrier at which predetermined distance the read beam is focussed on the information structure, a signal controlled objective drive means for advancing the objective system toward the record carrier information plane from a rest position at a distance exceeding said predetermined distance to a position closer than said predetermined distance and for moving said objective system away from said record carrier, first signal controlled electrical means for selectively connecting said focussing signal to said objective drive means in response to a first timing signal, second signal controlled electrical means connecting said focus detection means to said drive means through said frist signal controlled electrical means for selectively amplifying the focussing signals that advance and move back the objective system in response to a second timing signal and for selectively amplifying and amplitude limiting only those focussing signals that advance the objective system in response to an absence of said second timing, signal, third signal controlled electrical means responsive to an absence of said second timing signal for selectively adding to said focussing signals an electrical bias signal that tends to advance the objective system at a substantially uniform rate toward the record carrier and for providing velocity feedback to said objective drive means through said first signal controlled electrical means, thereby advancing said objective system at a substantially fixed velocity in response to an absence of said second timing signal, and clock means for providing said first timing signal for said first signal controlled electrical means and for concurrently providing an absence of said second timing signal for said second and third signal controlled electrical means to advance the objective system from said rest position toward said record carrier at a substantially fixed velocity and for providing said second timing signal at a time after the initiation of the first timing signal calculated to be such that the objective system is closer to the record carrier than said predetermined distance
Claim 3
Dependent Claim
108 words
An apparatus as reciited in claim 1 wherein said third signal controlled electrical means comprises an operational amplifier having at least two inputs and an output, a first of the two inputs of said operational amplifier being connected to said electrical focussing signal of said focus detection means, an auxiliary voltage source connected to a second input of said operational amplifier, and a first signal controlled switch connected to said auxiliary voltage sosurce and to said second input of said operational amplifier for controlling the application of said auxiliary voltage to said second input of said operational amplifier in response to an absence of said second timing signal.
Claim 4
Dependent Claim
57 words
An apparatus as recited in claim 2, wherein said second signal controlled dectrical means comprises a transistor amplifier, two opposite bias sources, means connecting said transistor amplifier directly to one of said bias sources, and a second signal controlled switch selectively connecting said opposite bias source to said transistor amplifier in response to said second timing signal.
Claim 5
Dependent Claim
58 words
An apparatus as recited in claim 2, wherein said signal controlled objective drive means comprises a coil disposed in a magnetic field, and wherein said velocity feedback of said third signal controlled electrical means comprises a bridge circuit including said coil, and a diode connecting said bridge circuit to said operational amplifier and said first signal controlled switch.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-08-10 | 1980-02-09 | 1980-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-10 | 1984-02-09 | 1984-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-10 | 1988-02-09 | 1988-08-10 | $7700.00 | Window Closed / Lapsed |