US3876876A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camera exposure time control device
Assignee: Seiko Koki KK
•
Filing: 1973-10-16
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Granted: 1975-04-08
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Expires: 1993-10-16
Abstract
Abstract A device which determines the exposure time in a camera for a sensed scene brightness and in accordance with exposure time factors such as the ASA number of the film and the f-stop setting. The brightness of the scene is converted into a pulse train which is fed into a binary counter which develops the exposure time count. A switch is settable in accordance with the exposure time factors changes the input position of the pulse train into the counter thus varying the magnitude of the exposure time count for the number of pulses in the pulse train. The exposure time corresponds to the mangitude of the exposure time count and thus is determined in accordance with the brightness of the scene bring photographed and the predetermined exposure time factors.
Inventors
- 👤 Kiyoshi Kitai
- 👤 Shinji Nagaoka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:28
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/091; G03B7/093
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
265 words
A device for determining the exposure time in a camera for a sensed scene brightness and in accordance with predetermined exposure time facors comprising: means responsive during use to the brightness of a scene to be photographed for developing an electric pulse train signal having a number of pulses in inverse proportion to the brightness of the scene; means receptive of said electric pulse train signal for converting same into an exposure time count corresponding in time to the exposure time and having a magnitude which varies for the number of pulses received in accordance with predetermined exposure time factors comprising counting means for counting the number of pulses in said electric pulse train signal including a first group of counting elements wherein any one of which is receptive at the input thereof of said electric pulse train signal and a second group of counting elements developing a count which corresponds to the exposure time count wherein the magnitude of the final count depends upon which one of said first group of counting elements receives said electric pulse train signal, and switching means connected between the first mentioned means and said counting means receptive of said electric pulse train signal and settable to positions corresponding to predetermined exposure time factors for selectively applying said electric pulse train signal to alternative ones of said first group of counting elements in accordance with predetermined corresponding exposure time factors; whereby the magnitude of the exposure time count and thereby the exposure time is determined in accordance with brightness of the scene being photographed and predetermined exposure time factors.
Claim 2
Independent Claim
265 words
A device for determining the exposure time in a camera for a sensed scene brightness and in accordance with predetermined exposure time facors comprising: means responsive during use to the brightness of a scene to be photographed for developing an electric pulse train signal having a number of pulses in inverse proportion to the brightness of the scene; means receptive of said electric pulse train signal for converting same into an exposure time count corresponding in time to the exposure time and having a magnitude which varies for the number of pulses received in accordance with predetermined exposure time factors comprising counting means for counting the number of pulses in said electric pulse train signal including a first group of counting elements wherein any one of which is receptive at the input thereof of said electric pulse train signal and a second group of counting elements developing a count which corresponds to the exposure time count wherein the magnitude of the final count depends upon which one of said first group of counting elements receives said electric pulse train signal, and switching means connected between the first mentioned means and said counting means receptive of said electric pulse train signal and settable to positions corresponding to predetermined exposure time factors for selectively applying said electric pulse train signal to alternative ones of said first group of counting elements in accordance with predetermined corresponding exposure time factors; whereby the magnitude of the exposure time count and thereby the exposure time is determined in accordance with brightness of the scene being photographed and predetermined exposure time factors.
Claim 3
Dependent Claim
73 words
A device according to claim 1, wherein said means for developing an electric pulse train signal comprises means responsive to the brightness of the sensed scene for developing an output signal having a time duration inversely proportional to the brightness of the sensed scene, a pulse generator for developing a continuous pulse train and gating means receptive of said output signal and said continuous pulse train for generating said electric pulse train signal.
Claim 4
Dependent Claim
14 words
A device according to claim 2, wherein said gating means comprises an AND gate.
Claim 5
Dependent Claim
15 words
A device according to claim 1, wherein said counting means comprises a binary digital counter.
Claim 6
Dependent Claim
14 words
A device according to claim 4, wherein said binary counter is an up-down counter.
Claim 7
Dependent Claim
29 words
A device according to claim 1, further comprising indicating means receptive of the exposure time count in said second group of counting elements for indicating the corresponding exposure time.
Claim 8
Dependent Claim
37 words
A device according to claim 6, wherein said indicating means comprises a switching element connected to each output of said second group of counting elements and an indicator lamp connected to each switching element and enabled thereby.
Claim 9
Dependent Claim
27 words
A device according to claim 7, wherein said indicating means further comprises means for enabling only the one indicating lamp corresponding to exposure time count to light.
Claim 10
Dependent Claim
68 words
A device according to claim 1, wherein said counting means comprises an up-down binary counter for developing the exposure time count equal to N and further comprising means for counting the binary counter down at a frequency equal to the exposure time divided by N, means for sensing the count in said up-down binary counter equal to zero and for developing a shutter closing signal in response thereto.
Claim 11
Dependent Claim
14 words
A device according to claim 1, wherein said switching means comprises a multi-contact switch.
References Cited (Backward Citations)
US3646371A
Cited
US3703130A
Cited
US3762285A
Cited
US3748979A
Cited
US3765311A
Cited
US3711721A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |