US3638543A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic exposure system for photographic camera
Assignee: Olympus Corp
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Filing: 1970-07-17
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Granted: 1972-02-01
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Expires: 1990-07-17
Abstract
Abstract An automatic exposure system for use with a camera of the type which includes a light-sensing device and a diaphragm-adjusting mechanism actuated thereby. The exposure system includes a first variable resistor serially connected to the diaphragm-adjusting mechanism but mechanically altered as the focus of the camera is altered. The flash unit with which the camera operates includes a second variable resistor which is adjusted according to the guide number of the flash unit. When the flash unit is coupled to the camera, the first and second variable resistors are placed in series, via the same leads that connect to the synchronization contacts on the camera shutter, with the automatic diaphragm. In this manner, the correct exposure is ensured, since the division of the camera-to-object distance into the guide number is done automatically by the current-limiting effects of the first and second resistors.
Inventors
- 👤 Isao Kondo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 19:15
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325; G; G03; G03B; G03B15/00; G03B15/02; G03B15/03; G03B15/05; G03B7/00; G03B7/16; G03B2215/00; G03B2215/05
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
190 words
An automatic exposure system comprising the combination of a camera and a photoflash unit, said camera comprising, in series, a source of potential; a light-sensitive device; a diaphragmadjusting mechanism; and a pair of contacts coupled to the shutter of said camera; said photoflash unit comprising a source of potential; a photoflash tube connected to said source; and means for triggering said tube into conduction, said latter means being connected to said camera shutter contacts By at least a pair of conductors, wherein the improvement comprises: a first variable resistor serially connected to said diaphragmadjusting mechanism and mechanically connected to, and varied by, the focus ring of said camera; and a second variable resistor connected to said photoflash source of potential and adjusted in accordance with the guide number of said photoflash unit, said first and second resistors forming a series circuit with said diaphragm-adjusting mechanism and said photoflash source, whereby the current passing through said diaphragm-adjusting mechanism, and hence the aperture of said camera, is varied as the focus of said camera is altered and the guide number of said photoflash unit changes, thereby ensuring proper exposure in said camera.
Claim 2
Dependent Claim
190 words
An automatic exposure system comprising the combination of a camera and a photoflash unit, said camera comprising, in series, a source of potential; a light-sensitive device; a diaphragmadjusting mechanism; and a pair of contacts coupled to the shutter of said camera; said photoflash unit comprising a source of potential; a photoflash tube connected to said source; and means for triggering said tube into conduction, said latter means being connected to said camera shutter contacts By at least a pair of conductors, wherein the improvement comprises: a first variable resistor serially connected to said diaphragmadjusting mechanism and mechanically connected to, and varied by, the focus ring of said camera; and a second variable resistor connected to said photoflash source of potential and adjusted in accordance with the guide number of said photoflash unit, said first and second resistors forming a series circuit with said diaphragm-adjusting mechanism and said photoflash source, whereby the current passing through said diaphragm-adjusting mechanism, and hence the aperture of said camera, is varied as the focus of said camera is altered and the guide number of said photoflash unit changes, thereby ensuring proper exposure in said camera.
Claim 3
Dependent Claim
63 words
The system according to claim 1, wherein said camera further comprises a third variable resistor, connected in parallel with said diaphragm-adjusting mechanism, said resistor being varied in accordance with the speed of the film loaded in said camera so that the current flowing through said mechanism, and hence the aperture of said camera, is compensated for variations in the speed of said film.
Claim 4
Dependent Claim
92 words
The system according to claim 1, wherein said photoflash unit includes a first capacitor which is charged by said source of potential to fire said photoflash tube, and said camera further comprises a first neon lamp, physically located so as to be visible in the viewfinder finder of said camera, said neon lamp being connected in the series circuit including said first and second variable resistors and being illuminated when said first capacitor becomes fully charged, thereby indicating to the eye of a user, that said photoflash unit is ready for use.
Claim 5
Dependent Claim
136 words
The system according to claim 1, wherein said triggering means comprises a triggering transformer having a secondary winding connected to a triggering electrode on said photoflash tube; and a triggering capacitor chargeable through said second variable resistor, said flash unit further comprising: a thyristor having its anode-cathode path in parallel with the primary of said triggering transformer and its trigger electrode connected to ground, the cathode of said thyristor being connected to ground via a first fixed resistor, one plate of said triggering capacitor being connected to the juncture of said cathode and said first fixed resistor, whereby, when said shutter contacts are closed, said triggering capacitor discharges through said first fixed resistor, thereby firing said thyristor which, in turn, applies a current pulse to said triggering transformer to thereby initiate conduction in said photoflash tube.
Claim 6
Dependent Claim
65 words
The system according to claim 4, wherein said camera further comprises switch means for selectively interrupting the series circuit including the first variable resistor in said camera and the second variable resistor in said photoflash unit, whereby said first variable resistor cooperates with the potential source in said camera, and said light-sensitive device, to control the exposure in said camera independently of said photoflash unit.
Claim 7
Dependent Claim
78 words
The system according to claim 4, wherein said photoflash unit includes switching means for energizing said photoflash tube from an external source of AC current, while maintaining the connection of said source of potential as the current supplying source for the series connection of said first and second variable resistors, and said diaphragm, whereby the aperture setting of said camera is rendered immune to variations due to noise and fluctuations in the potential of said external AC source.
Claim 8
Dependent Claim
71 words
The system according to claim 4, wherein said photoflash unit includes a neon lamp serially connected between said second variable resistor and one of said pair of conductors interconnecting said photoflash unit and said camera, and said camera further comprises amplifying means, serially connected in the circuit including said first and second variable resistors, for amplifying the current flowIng therethrough; whereby the range of adjustment of said diaphragm-adjusting mechanism is extended.
Claim 9
Dependent Claim
38 words
The system according to claim 7, wherein said amplifying means comprises a transistor in common emitter configuration, said first variable resistor being serially connected in the collector circuit thereof; and means for biasing said transistor into linear operation.
Claim 10
Dependent Claim
65 words
The system according to claim 8, wherein said camera further comprises switching means for interrupting the serial connection of said first and second variable resistors and establishing, in lieu thereof, a connection between said first variable resistor and a first compensating resistor, having one end thereof connected to said diaphragm-adjusting mechanism, whereby the exposure of said camera is automatically controlled independently of said photoflash unit.
Claim 11
Dependent Claim
41 words
The system according to claim 9, wherein said switching means is adapted to selectively associate said transistor amplifier with said light-sensitive device whereby the light-sensitive device may be utilized to control the aperture of said camera in light of low intensity.
Claim 12
Dependent Claim
73 words
The system according to claim 7, wherein said camera further includes a fourth variable resistor, connected in parallel with said diaphragm-adjusting mechanism, said resistor being varied in accordance with the speed of the film loaded in said camera so that the current flowing through said mechanism, and hence the aperture of said camera, is compensated for variations in the speed of said film, in the extended range made possible by said amplifying means.
References Cited (Backward Citations)
US3424071A
Cited
US3521540A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |