US3798660A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic focusing device for cameras
Assignee: Canon Inc
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Filing: 1972-10-03
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Granted: 1974-03-19
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Expires: 1992-10-03
Abstract
Abstract This specification discloses an automatic focusing device for cameras in which a mirror member is provided between a photographic optical system and a range finding optical system and the photographic optical system is moved by a servomotor while the mirror member is being moved up from its range finding position to its picture-taking position. Thereafter, the servomotor holds the optical system in the picture-taking position to accomplish picture-taking.
Inventors
- 👤 M Yamamichi
- 👤 G Hasegawa
- 👤 Y Iura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:56
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/34
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
190 words
A photographic camera provided with an automatic focusing device, comprising: a photographic optical lens system including an objective Lens; a mirror member provided between said objective lens and a sensitive film surface; drive means drivingly connected with said mirror member for driving said mirror member between a first position for intercepting light directed from said objective lens to the film surface and a second position in which light directed to said film surface is not intercepted; a range finding light-receiving photoelectric element disposed in conjugate relationship with the film surface and disposed to receive light intercepted as aforesaid when said mirror member is placed at said first position; and focus detection control circuit means receiving the output of said photoelectric element, said circuit means including: a servomotor drivingly connected with said photographic optical lens system; a drive circuit for driving said servomotor; and hold switching means provided in said drive circuit for electrically energizing and deenergizing said motor, said switching means being arranged to shift from its ON position to its OFF position in synchronism with the displacement of said mirror member from said first position to said second position.
Claim 2
Dependent Claim
190 words
A photographic camera provided with an automatic focusing device, comprising: a photographic optical lens system including an objective Lens; a mirror member provided between said objective lens and a sensitive film surface; drive means drivingly connected with said mirror member for driving said mirror member between a first position for intercepting light directed from said objective lens to the film surface and a second position in which light directed to said film surface is not intercepted; a range finding light-receiving photoelectric element disposed in conjugate relationship with the film surface and disposed to receive light intercepted as aforesaid when said mirror member is placed at said first position; and focus detection control circuit means receiving the output of said photoelectric element, said circuit means including: a servomotor drivingly connected with said photographic optical lens system; a drive circuit for driving said servomotor; and hold switching means provided in said drive circuit for electrically energizing and deenergizing said motor, said switching means being arranged to shift from its ON position to its OFF position in synchronism with the displacement of said mirror member from said first position to said second position.
Claim 3
Dependent Claim
21 words
A photographic camera according to claim 1, wherein said hold switching means comprises a switch mechanically linked with said mirror member.
Claim 4
Dependent Claim
149 words
A photographic camera according to claim 1, wherein said control circuit means further includes; second hold switching means connected in said motor drive circuit arranged to permit interruption of said motor drive circuit only in a predetermined position of said photographic optical lens system; a constant time limit circuit adapted to start timing in response to shutter release and to continue such timing for a predetermined time; and electromagnet means connected with the output of said time limit circuit, said electromagnet means being arranged to block the interruption of said motor drive circuit by said second hold switching means from the time of shutter release until said predetermined time thereafter, whereby when said photographic optical lens system next reaches its said predetermined position under drive of said motor, said second hold switching means is changed over from its ON position to its OFF position to electrically deenergize said motor.
Claim 5
Dependent Claim
15 words
A photographic camera according to claim 1, wherein said mirror member is a rotatable shutter.
Claim 6
Dependent Claim
16 words
A photographic camera according to claim 1, wherein said mirror is a vertically movable quick-return mirror.
Claim 7
Dependent Claim
69 words
A photographic camera according to claim 1, wherein said control circuit means further includes: a switching circuit having the input thereof connected with said light receiving element; and a switch member adapted to be changed over by the output of said switching circuit, said switch member being connected in said motor drive circuit; whereby said motor drive circuit is opened when said mirror member is in its second position.
Claim 8
Dependent Claim
66 words
A photographic camera according to claim 1, wherein said control circuit means further includes a switching circuit having the input thereof connected with said light-receiving element and a flipflop circuit adapted to be reset through the switching circuit when output of said light-receiving element reaches an extreme value thereof, and wherein, further, said servomotor is connected to be driven by the output of the flipflop circuit.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |