US3680457A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camera having a preliminary flash illumination for exposure determination
Assignee: Pentax Corp
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Filing: 1970-06-01
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Granted: 1972-08-01
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Expires: 1990-06-01
Abstract
Abstract A camera for controlling exposure in accordance with the light intensity of a preliminary flash. This light from the preliminary flash first passes through the objective of the camera and then is received by a light-detecting unit for measuring the light intensity. Information measured by the latter unit is used for controlling the exposure, so that the latter control is achieved with light which has already passed through the camera objective.
Inventors
- 👤 Naoyuki Uno
- 👤 Seijiro Tokutomi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:59
CPC Classifications
G; G03; G03B; G03B15/00; G03B15/02; G03B15/03; G03B15/05; G03B7/00; G03B7/16; G03B2215/00; G03B2215/05
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
227 words
In a camera, an objective, flash means for providing flash illumination, preliminary actuating means coacting with said flash means for actuating the latter to provide a preliminary flash illumination, light-directing means situated in the path of light travel subsequent to said objective for directing light which has passed through said objective along a predetermined path, detecting means situated along the latter path for detecting the intensity of the light of said preliminary flash illumination as well as the intensity of any ambient light after the light has passed through said objective to be directed along said path by said light-directing means, primary actuating means coacting with said flash means for actuating the latter to provide a primary flash to be used during actual film exposure, and control means operatively connected with said detecting means and actuated, in accordance with the light intensity detected thereby, for determining the extent of exposure, said detecting means measuring and memorizing the intensity of light from the preliminary flash and from any ambient source, said control means responding to the information memorized by said detecting means for controlling the exposure, the camera also including a shutter which is opened to initiate an exposure and closed to terminate the exposure, said control means coacting with said shutter for closing the latter after an interval determined by the information memorized by said detecting means.
Claim 2
Dependent Claim
227 words
In a camera, an objective, flash means for providing flash illumination, preliminary actuating means coacting with said flash means for actuating the latter to provide a preliminary flash illumination, light-directing means situated in the path of light travel subsequent to said objective for directing light which has passed through said objective along a predetermined path, detecting means situated along the latter path for detecting the intensity of the light of said preliminary flash illumination as well as the intensity of any ambient light after the light has passed through said objective to be directed along said path by said light-directing means, primary actuating means coacting with said flash means for actuating the latter to provide a primary flash to be used during actual film exposure, and control means operatively connected with said detecting means and actuated, in accordance with the light intensity detected thereby, for determining the extent of exposure, said detecting means measuring and memorizing the intensity of light from the preliminary flash and from any ambient source, said control means responding to the information memorized by said detecting means for controlling the exposure, the camera also including a shutter which is opened to initiate an exposure and closed to terminate the exposure, said control means coacting with said shutter for closing the latter after an interval determined by the information memorized by said detecting means.
Claim 3
Dependent Claim
33 words
The combination of claim 1 and wherein the camera includes a viewfinder, and said light directing means directing light which has passed through the objective through the viewfinder before reaching said detecting means.
Claim 4
Dependent Claim
93 words
The combination of claim 2 and wherein the camera is a single lens reflex camera having a prism viewfinder and a tiltable reflector forming part of said light-directing means and directing light which has passed through the objective into said prism viewfinder, the latter being located along said path for directing light from the viewfinder to said detecting means, said tiltable reflector reflecting light of the preliminary flash through the viewfinder and to said detecting means before tilting of the reflector to a position situated beyond the optical axis when film is exposed.
Claim 5
Dependent Claim
49 words
The combination of claim 1 and wherein said flash means provides when actuated by said preliminary actuating means light which, except for the amount of light, is of the same characteristics as the light provided by said flash means when the latter is actuated by said primary actuating means.
Claim 6
Dependent Claim
46 words
The combination of claim 1 and wherein said control means includes a bypass emission means which is rendered conductive for terminating emission of light by said flash means after an interval determined by the memorized information of said detecting means to which said control means responds.
Claim 7
Dependent Claim
72 words
The combination of claim 1 and wherein said flash means consists only of a single light source, said preliminary actuating means including a preliminary voltage source and a preliminary actuator while said primary actuating means includes a primary voltage source and a primary actuator, and change-over means coacting with said sources and actuators for changing the operation over from saId preliminary voltage source and actuator to said primary voltage source and actuator.
Claim 8
Dependent Claim
59 words
The combination of claim 1 and wherein said control means includes a timing circuit for providing a controlled time interval for determining said exposure, said timing circuit including a current controlling element and a capacitor and the information memorized by said detecting means being converted into a given internal resistance of said current controlling element of said timing circuit.
Claim 9
Dependent Claim
106 words
The combination of claim 1 and wherein said control means includes an electrical circuit having a current controlling element the internal resistance of which is determined by the information memorized by said detecting means, said electrical circuit having a voltage dividing portion for the voltage source of the flash means during primary flash illumination, the latter voltage dividing portion containing said current controlling element and a resistor, and said control means determining the extent of exposure in accordance with the dropping of the divided voltage value of said voltage dividing portion of said circuit to a value which will provide a proper exposure with flash illumination.
Claim 10
Dependent Claim
72 words
The combination of claim 1 and wherein the camera includes a manually-actuated shutter element for initiating shutter operation, said shutter element being operatively connected with said preliminary actuating means for operating the latter prior to actual opening of the shutter to make an exposure, said shutter element then operating said primary actuating means and providing opening of the camera shutter after the detecting means had detected the light of said preliminary flash.
Claim 11
Dependent Claim
48 words
The combination of claim 9 and wherein said control means includes an electrical circuit having a timing capacitor and a short-circuit switch bypassing said capacitor when said switch is closed, said shutter element opening the latter switch simultaneously with the opening of the shutter to make an exposure.
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) | 1975-08-01 | 1976-01-31 | 1976-08-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-01 | 1980-01-31 | 1980-08-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-01 | 1984-01-31 | 1984-08-01 | $7700.00 | Window Closed / Lapsed |