US3735686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camera systems
Assignee: SIDNEY R LITTLEJOHN & CO LTD
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Filing: 1971-11-22
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Granted: 1973-05-29
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Expires: 1991-11-22
Abstract
Abstract A constant focus drive apparatus for controlling the positioning of an object and a lens arrangement in a camera system relative to a desired plane so as to keep an image of the object focused in such plane, comprising means e.g. potentiometers for measuring the object and image distances and for producing distance signals representative thereof, drive means e.g. one or more servo systems and/or a manually controlled motor connected to the camera system for varying both the object and image distances, and a computer which may be analogue or digital and may use electricity, pneumatic or hydraulic power, or other powering medium and which is programmed with the lens formula of the camera system to compute, in accordance with the measured values of the object and image distances, a control signal for application to the drive means to alter one or both of said distances as necessary so that the image is kept focused in said plane.
Inventors
- 👤 T Brewer
- 👤 R Blundell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:45
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/32; G03B27/34
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
284 words
Apparatus for controlling the positioning of an object and a lens arrangement in a camera system relative to a desired plane so as to produce an image of the object in such plane, comprising means for measuring the object distance and for producing a first distance signal representative thereof, means for measuring the image distance and for producing a second distance signal representative thereof; drive means connected to the camera system for varying both the object and image distances, and an analogue computer connected to both said measuring means so as to receive said first and second distance signals and programmed to compute, in accordance with the measured values of said distance signals, a control signal for application via an output thereof to said drive means to alter one of said distances as necessary so that the image is produced in said plane, said computer comprising a first operational amplifier circuit having a feedback network arranged to give the circuit a gain equal to the negative focal length of the lens arrangement of the camera system and an input connected to receive the first and second distance signals, a second operational amplifier circuit having a feedback network arranged to give the circuit a gain of negative unity and an input connected to receive one of said distance signals and a node offset signal for said one distance signal, and a third operational amplifier having a feedback network arranged to give the circuit a gain equal to the negative of the other of said distance signals and an input connected to the output of said second circuit, the outputs of said first and third circuits being connected together and to said output of the computer.
Claim 2
Dependent Claim
284 words
Apparatus for controlling the positioning of an object and a lens arrangement in a camera system relative to a desired plane so as to produce an image of the object in such plane, comprising means for measuring the object distance and for producing a first distance signal representative thereof, means for measuring the image distance and for producing a second distance signal representative thereof; drive means connected to the camera system for varying both the object and image distances, and an analogue computer connected to both said measuring means so as to receive said first and second distance signals and programmed to compute, in accordance with the measured values of said distance signals, a control signal for application via an output thereof to said drive means to alter one of said distances as necessary so that the image is produced in said plane, said computer comprising a first operational amplifier circuit having a feedback network arranged to give the circuit a gain equal to the negative focal length of the lens arrangement of the camera system and an input connected to receive the first and second distance signals, a second operational amplifier circuit having a feedback network arranged to give the circuit a gain of negative unity and an input connected to receive one of said distance signals and a node offset signal for said one distance signal, and a third operational amplifier having a feedback network arranged to give the circuit a gain equal to the negative of the other of said distance signals and an input connected to the output of said second circuit, the outputs of said first and third circuits being connected together and to said output of the computer.
Claim 3
Dependent Claim
38 words
Apparatus as claimed in claim 1, wherein each of said measuring means comprises a potentiometer and means for keeping a wiper of the potentiometer spaced from an end thereof by an amount proportional to the distance being measured.
Claim 4
Dependent Claim
46 words
Apparatus as claimed in claim 1, wherein said drive means includes a servo system connected to the outputs of said computer and arranged for varying said one of the object and image distances, and a manually controlled motor arranged for varying the other of said distances.
Claim 5
Dependent Claim
48 words
Apparatus as claimed in claim 1, wherein said inputs of said first and second operational amplifier circuits receive said distance signals by way of a pair of voltage follower circuits each connected by a respective one of said measuring means for passing a respective one of said signals.
Claim 6
Dependent Claim
40 words
Apparatus as claimed in claim 1, wherein said feedback network of said operational amplifier circuit includes a circuit component representative of said focal length and mounted in the lens mount of the camera system for detachable connection into said network.
Claim 7
Dependent Claim
43 words
Apparatus as claimed in claim 1, wherein said feedback network of said third operational amplifier circuit includes a variable value circuit component and means for varying the value thereof in accordance with the magnitude of the other of said object and image distances.
Claim 8
Dependent Claim
94 words
Apparatus as claimed in claim 1, wherein said analogue computer further comprises a fourth operational amplifier circuit having a feedback network arranged to give the circuit a gain equal to the negative reciprocal of the focal length of the lens arrangement of the camera system and an input connected to receive said first and second distance signals and connected To the output of said second operational amplifier circuit, and display means having a first input connected to the output of said fourth circuit and a second input connected to receive a negative unity signal.
Claim 9
Dependent Claim
38 words
Apparatus as claimed in claim 7, wherein each of said measuring means comprises a potentiometer and means for keeping a wiper of the potentiometer spaced from an end thereof by an amount proportional to the distance being measured.
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) | 1976-05-28 | 1976-11-27 | 1977-05-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-05-28 | 1980-11-27 | 1981-05-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-05-28 | 1984-11-27 | 1985-05-29 | $7700.00 | Window Closed / Lapsed |