US3657979A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic exposure controls for cameras
Assignee: Pentax Corp
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Filing: 1970-06-30
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Granted: 1972-04-25
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Expires: 1990-06-30
Abstract
Abstract A camera capable of having the exposure of film therein determined automatically. A shutter actuator is provided for first opening the shutter to start an exposure and for then closing the shutter to terminate the exposure, and a shutter circuit coacts with the shutter actuator to start measuring of an exposure time interval when the shutter is opened and to operate the shutter actuator to close the shutter after elapse of an exposure time which will provide a proper exposure. The shutter circuit is transistorized and includes a triggering capacitor for triggering the shutter circuit to bring about closure of the shutter. A storage circuit is provided for storing information which includes the factor of the intensity of the light received from the object which is photographed, and this storage circuit includes a storage capacitor the charge of which is indicative of the light intensity. A control circuit is connected electrically both with the storage circuit and with the shutter circuit for triggering the latter through the triggering capacitor, to bring about closing of the shutter, in accordance with the charge at the storage capacitor.
Inventors
- 👤 Tsukumo Nobusawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:23
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
291 words
In a camera, storage circuit means for storing exposuredetermining information at least part of which includes the factor of the intensity of the light received from the object which is photographed, said storage circuit means including a storage capacitor, a charging circuit electrically connected with said storage capacitor for charging the same, and a timing circuit electrically connected in parallel with said storage capacitor for determining the duration during which the latter is charged, said timing circuit including a light-responsive means for providing at said storage capacitor a charge in accordance with said light intensity, a timing capacitor in series with said light-responsive means, and a transistor connected to the junction of said timing capacitor and light-responsive means for becoming conductive when said timing capacitor is charged to a given extent and for then interrupting charging of said storage capacitor, shutter-actuating means for first opening a shutter of the camera to commence an exposure and for then closing the shutter to terminate the exposure, shutter circuit means electrically connected with said shutter-actuating means for responding to opening of the shutter thereby to measure exposure time and for providing at said shutter-actuating means a shutterclosing operation after elapse of an exposure time which will provide a proper exposure for the conditions under which the exposure is made, said shutter circuit means including a triggering capacitor for triggering said shutter circuit means to provide said shutter-closing operation by said shutter-actuating means in accordance with the charge of said triggering capacitor, and control circuit means electrically connected between said storage capacitor of said storage circuit means and said triggering capacitor of said shutter circuit means for controlling the latter to terminate an exposure in accordance with the information stored in said storage circuit means.
Claim 2
Dependent Claim
291 words
In a camera, storage circuit means for storing exposuredetermining information at least part of which includes the factor of the intensity of the light received from the object which is photographed, said storage circuit means including a storage capacitor, a charging circuit electrically connected with said storage capacitor for charging the same, and a timing circuit electrically connected in parallel with said storage capacitor for determining the duration during which the latter is charged, said timing circuit including a light-responsive means for providing at said storage capacitor a charge in accordance with said light intensity, a timing capacitor in series with said light-responsive means, and a transistor connected to the junction of said timing capacitor and light-responsive means for becoming conductive when said timing capacitor is charged to a given extent and for then interrupting charging of said storage capacitor, shutter-actuating means for first opening a shutter of the camera to commence an exposure and for then closing the shutter to terminate the exposure, shutter circuit means electrically connected with said shutter-actuating means for responding to opening of the shutter thereby to measure exposure time and for providing at said shutter-actuating means a shutterclosing operation after elapse of an exposure time which will provide a proper exposure for the conditions under which the exposure is made, said shutter circuit means including a triggering capacitor for triggering said shutter circuit means to provide said shutter-closing operation by said shutter-actuating means in accordance with the charge of said triggering capacitor, and control circuit means electrically connected between said storage capacitor of said storage circuit means and said triggering capacitor of said shutter circuit means for controlling the latter to terminate an exposure in accordance with the information stored in said storage circuit means.
Claim 3
Dependent Claim
27 words
The combination of claim 1 and wherein a manually operable means is operatively connected with said storage circuit means for closing the latter to initiate an exposure.
Claim 4
Dependent Claim
77 words
The combination of claim 1 and wherein said shutter circuit means includes transistors which when triggered operate said shutter-actuating means to close the shutter, and said triggering capacitor triggering the transistors of said shutter circuit means to bring about closing of the shutter, said timing circuit of said storage circuit means being electrically connected with said storage capacitor for maintaining the charging thereof for an interval the magnitude of which is in accordance with said light intensity.
Claim 5
Dependent Claim
43 words
The combination of claim 3 and wherein said control circuit means is operatively connected between said capacitors for triggering said shutter circuit means by said triggering capacitor thereof when the charge of the latter is equal to the charge of said storage capacitor.
Claim 6
Dependent Claim
64 words
The combination of claim 4 and wherEin said control circuit means has a transistor and an output terminal connected to the emitter of said transistor, said shutter circuit means having a triggering transistor provided with an emitter electrically connected with said output terminal, and an emitter resistor also connected electrically with sad output terminal and being common to said control and shutter circuit means.
Claim 7
Dependent Claim
35 words
The combination of claim 3 and wherein a pair of variable resistors are electrically connected in series with said capacitors, respectively, for introducing into said circuits additional exposure-determining factors of film speed and diaphragm aperture.
Claim 8
Dependent Claim
42 words
The combination of claim 3 and wherein said control circuit means is a comparison circuit for comparing the charges of said capacitors for triggering said shutter circuit means through said triggering capacitor according to the differential between the charges at said capacitors.
Claim 9
Dependent Claim
70 words
The combination of claim 3 and wherein a diode, additional capacitor, and variable resistor are connected electrically on the one hand with said storage capacitor and on the other hand with said triggering capacitor for forming circuits where the electrical signals are directly proportional to time with said variable resistors being adjustable for addition of exposure factors other than the intensity of light received from the object which is photographed.
Claim 10
Dependent Claim
77 words
The combination of claim 1 and wherein said storage circuit means includes a timing portion for operating said storage circuit means for a given time and said storage circuit means storing at said storage capacitor a plurality of pulses the number of which is indicative of the light intensity, said control circuit means bringing about triggering of said shutter circuit means through said triggering capacitor in accordance with the number of pulses stored at said storage capacitor.
Claim 11
Dependent Claim
54 words
The combination of claim 3 and wherein said storage capacitor receives its charge just prior to opening of the shutter to initiate operation of said shutter circuit means, said storage circuit means including a relay which terminates operation of said storage circuit means just prior to opening of the shutter by said shutter-actuating means.
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) | 1975-04-25 | 1975-10-25 | 1976-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-25 | 1979-10-25 | 1980-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-25 | 1983-10-25 | 1984-04-25 | $7700.00 | Window Closed / Lapsed |