US3914776A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shutter control device
Assignee: Minolta Co Ltd
•
Filing: 1970-06-11
•
Granted: 1975-10-21
•
Expires: 1990-06-11
Abstract
Abstract A shutter control device comprises three timing circuits and a switching circuit, and in a first timing circuit a first capacitor is charged by photoconductive current generated by a photoconductive cell. The switching circuit is controlled by the voltage of the first capacitor. A second timing circuit has a second capacitor the charging of which is actuated by the switching circuit simultaneously with the actuation of the first timing circuit and is charged as a function of the delay of the first timing circuit. A third timing circuit has a third capacitor and a shorting switch opened in response to the shutter opening after the first capacitor is charged to a predetermined level. The switching circuit triggers shutter closing through an electromagnet when the third capacitor is charged to the voltage equal to that of the second capacitor.
Inventors
- 👤 Kayoshi Tsujimoto
- 👤 Kintaro Yata
- 👤 Yoshifusa Fujii
- 👤 Hiroshi Ueda
- 👤 Motonobu Matsuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:45
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
224 words
A shutter opening and closing device for a photographic camera including a shutter opening mechanism, a shutter closing mechanism, and a light responsive element normally exposed to scene light through an objective lens of the camera and unexposed to the light while said shutter mechanisms are in operating condition, comprising: a first timing circuit including a first capacitor charged by current generated by said light responsive element; a switching circuit having an input connected to said first capacitor to be switched when said first capacitor is charged to a predetermined voltage; a second timing circuit having a second capacitor and controlled by said switching circuit to charge to a voltage determined by said first timing circuit; a manually operable switch means for initiating the charging of said first and second capacitors simultaneously; a releasing member manually operable for actuating said switch means and then sequentially releasing said shutter opening mechanism; a third timing circuit having a third capacitor; an operating switch connected across said third capacitor and opened in response to the release of said shutter opening mechanism; means for actuating said shutter closing mechanism; means for comparing the terminal voltages of said second capacitor and the third capacitor and triggering said means for actuating said shutter closing mechanism when said third capacitor is charged to substantially the same voltage as said second capacitor.
Claim 2
Dependent Claim
224 words
A shutter opening and closing device for a photographic camera including a shutter opening mechanism, a shutter closing mechanism, and a light responsive element normally exposed to scene light through an objective lens of the camera and unexposed to the light while said shutter mechanisms are in operating condition, comprising: a first timing circuit including a first capacitor charged by current generated by said light responsive element; a switching circuit having an input connected to said first capacitor to be switched when said first capacitor is charged to a predetermined voltage; a second timing circuit having a second capacitor and controlled by said switching circuit to charge to a voltage determined by said first timing circuit; a manually operable switch means for initiating the charging of said first and second capacitors simultaneously; a releasing member manually operable for actuating said switch means and then sequentially releasing said shutter opening mechanism; a third timing circuit having a third capacitor; an operating switch connected across said third capacitor and opened in response to the release of said shutter opening mechanism; means for actuating said shutter closing mechanism; means for comparing the terminal voltages of said second capacitor and the third capacitor and triggering said means for actuating said shutter closing mechanism when said third capacitor is charged to substantially the same voltage as said second capacitor.
Claim 3
Dependent Claim
35 words
A shutter control device as in claim 1, wherein said first capacitor is selected to make the delay of said first timing circuit shorter than the actual exposure time determined by said third timing circuit.
Claim 4
Dependent Claim
35 words
A shutter control device as in claim 1, wherein said first capacitor is selected to make the delay of said first timing circuit longer than the actual exposure time determined by said third timing circuit.
Claim 5
Dependent Claim
40 words
A shutter control device as in claim 1, further comprising means for short-circuiting said second capacitor prior to the charging thereof and said second capacitor is charged by said switching circuit during the delay period of said first timing circuit.
Claim 6
Dependent Claim
37 words
A shutter control device as in claim 1, further comprising a power source for charging said second capacitor and said second capacitor is discharged by said switching circuit during said delay period of the first timing circuit.
Claim 7
Dependent Claim
44 words
A shutter control device as in claim 1, wherein said first and second timing circuits each include a plurality of alternatively selectable capacitors for a plurality of delay periods to be selected in accordance with the light conditions of a scene to be photographed.
Claim 8
Dependent Claim
39 words
A shutter control device as in claim 6, further comprising a pointer positioned in response to the intensity of light incident on said photoelectric cell, and means associated with said pointer for selecting one of said plurality of capacitors.
Claim 9
Dependent Claim
94 words
A shutter control device as in claim 1, wherein said first timing circuit includes a fourth capacitor having a higher capacitance than said first capacitor for providing a longer delay period than the actual exposure time, said second timing circuit includes a fifth capacitor having a higher capacitance than said second capacitor, and further comprising switching means associated with said first and second timing circuits for connecting said first and second capacitors or said fourth and fifth capacitors in said respective first and second timing circuits in accordance with the intensity of scene light.
Claim 10
Dependent Claim
95 words
A shutter control device as in claim 8, wherein said switching means includes: a voltage divider having said light responsive element and a fixed resistance connected in series therewith, first, second, third and fourth fixed contacts respectively connected to said first, second, fourth and fifth capacitors, first and second movable contacts, means for moving said first and second movable contacts respectively into contact with said first and fourth contacts and said second and fifth contacts, a second switching circuit controlled by said voltage diviDer for actuating said means for moving in response to scene light.
Claim 11
Dependent Claim
27 words
A shutter control device as in claim 1, further comprising means for triggering the shutter opening mechanism when said first capacitor is charged to a predetermined level.
Claim 12
Dependent Claim
20 words
A shutter control device as in claim 1, further comprising means for controlling the charging level of said first capacitor.
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) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |