US3896455A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus for controlling the exposure of photographic film
Assignee: C Reichert Optische Werke AG
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Filing: 1973-11-29
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Granted: 1975-07-22
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Expires: 1993-11-29
Abstract
Abstract Conversion of the signal from a light detector to a logarithmic value and the addition of similarly converted predetermined signals representing camera format, film sensitivity, correction factors and the like which are combined with the logarithmic light signal to be used to operate a display device reporting exposure time and converted to an analog value to operate a camera shutter device for obtaining improved exposures. Apparatus which provides improved exposures by this method includes a light detector and a set of controls for predetermining the signal magnitude of condition factors such as camera format, film sensitivity, correction factors and the like; means for converting each of these signals to a logarithmic value; computing means to combine these signals to a logarithmic signal useful for the direct display of exposure time and analog conversion means to provide a signal useable to control a camera shutter device to provide an exposure time equivalent to the display exposure time.
Inventors
- 👤 Alfred Steinbatz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:13
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085; G01; G01J; G01J1/00; G01J1/42; G01J1/4209; G01J1/4214; G03B27/00; G03B27/72; G03B27/80
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
269 words
A control for determining exposure time for photomicrographic apparatus and operating the shutter of said apparatus responsive to the influence of photographic environment such as camera format, film sensitivity and light flux comprising: means for generating an electrical signal responsive to the light flux adjacent a photographic subject including means for detecting light adjacent said subject, means for generating an electrical signal proportional thereto and means for converting said electrical signal to a second electrical signal proportional to the value of an exponent of a predetermined base value of said light value; means for generating an electric signal responsive to the format of said photographic apparatus including means for generating an electrical signal proportional to the value of an exponent of said predetermined base value of said format signal; means for generating an electric signal responsive to the sensitivity of the film of said photographic apparatus including means for generating an electric signal proportional to the value of an exponent of said predetermined base value of said sensitivity signal; means for generating an electric signal responsive to the change of sensitivity of the film of said photographic apparatus including means for generating an electric signal proportional to the value of an exponent of said predetermined base value of said change of sensitivity signal; means electrically connected to said exponential electric signal generating means for summing said signals including means for generating an output electric signal proportional to said sum; and means for displaying the relative value of said output signal and means connected to said output signal and said shutter for driving said shutter responsive to said output signal.
Claim 2
Dependent Claim
269 words
A control for determining exposure time for photomicrographic apparatus and operating the shutter of said apparatus responsive to the influence of photographic environment such as camera format, film sensitivity and light flux comprising: means for generating an electrical signal responsive to the light flux adjacent a photographic subject including means for detecting light adjacent said subject, means for generating an electrical signal proportional thereto and means for converting said electrical signal to a second electrical signal proportional to the value of an exponent of a predetermined base value of said light value; means for generating an electric signal responsive to the format of said photographic apparatus including means for generating an electrical signal proportional to the value of an exponent of said predetermined base value of said format signal; means for generating an electric signal responsive to the sensitivity of the film of said photographic apparatus including means for generating an electric signal proportional to the value of an exponent of said predetermined base value of said sensitivity signal; means for generating an electric signal responsive to the change of sensitivity of the film of said photographic apparatus including means for generating an electric signal proportional to the value of an exponent of said predetermined base value of said change of sensitivity signal; means electrically connected to said exponential electric signal generating means for summing said signals including means for generating an output electric signal proportional to said sum; and means for displaying the relative value of said output signal and means connected to said output signal and said shutter for driving said shutter responsive to said output signal.
Claim 3
Dependent Claim
25 words
A control according to claim 1 wherein the means for displaying a relative value of said output signal includes a visual display of exposure time.
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) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |