Patent US3907428A successfully refreshed from Google Patents.
US3907428A
Expired / Lapsed
US
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Reproduction camera having a control circuit for automatic regulation of the exposure time
Assignee: Eskofot AS
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Filing: 1974-10-07
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Granted: 1975-09-23
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Expires: 1994-10-07
Abstract
Abstract A reproduction camera having a control circuit for automatic regulation of the exposure time is provided, which includes a light-sensitive member which during the exposure is continuously sensing the light intensity in the high light area of the image plane. The described embodiment provides means for automatically regulating the time of exposure continuously in dependence on the amount of light falling on the light-sensitive member. The means for automatically regulating the time of exposure comprises a light dependent resistor which controls the electric current through a transistor, which serves as a constant current generator for charging a capacitor, which, when charged to a predetermined level, activates an electronic switch circuit to cut off the illuminating means and thereby terminate the exposure. The control circuit further comprises means for preselection of the time of exposure corresponding to a number of light-sensitive materials with different sensibilities.
Inventors
- 👤 Richard Arlund Norgaard
- 👤 Sven Nygaard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:55
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/80
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
159 words
In a reproduction camera having a control circuit for automatic regulation of the exposure time and comprising a supporting frame with three planes displaceable in relation to one another, said planes comprising an image plane, a copy plane and a lens plane, and further illuminating means for illuminating the object which is to be reproduced on a photosensitive medium, the improvement comprising light-sensitive means for continuously sensing the quantity of light from said illuminating means as modified by said object during exposure of said photosensitive medium by said modified light and providing an output signal varying as a function of incident light and means mounting said light-sensitive means for movement in a plane adjacent to and substantially parallel with the image plane, between said image and lens planes the control circuit further comprising means for receiving said output signal and automatically regulating the time of exposure continuously in dependence on the amount of light falling on the light-sensitive member.
Claim 2
Dependent Claim
159 words
In a reproduction camera having a control circuit for automatic regulation of the exposure time and comprising a supporting frame with three planes displaceable in relation to one another, said planes comprising an image plane, a copy plane and a lens plane, and further illuminating means for illuminating the object which is to be reproduced on a photosensitive medium, the improvement comprising light-sensitive means for continuously sensing the quantity of light from said illuminating means as modified by said object during exposure of said photosensitive medium by said modified light and providing an output signal varying as a function of incident light and means mounting said light-sensitive means for movement in a plane adjacent to and substantially parallel with the image plane, between said image and lens planes the control circuit further comprising means for receiving said output signal and automatically regulating the time of exposure continuously in dependence on the amount of light falling on the light-sensitive member.
Claim 3
Dependent Claim
85 words
In a camera as claimed in claim 1, the further improvement wherein said light-sensitive means is a light-dependent resistor, and wherein said control circuit includes a constant current generator capacitor and an electronic switch circuit and means connected to said light-sensitive means in such a manner that it regulates the strength of a current supplied by a constant current generator for charging a capacitor which, when charged to a predetermined level, activates an electronic switch circuit which causes the illuminating means to be cut off.
Claim 4
Dependent Claim
34 words
In a camera as claimed in claim 1, the further improvement comprising means for preselecting one of a plurality of exposure times, each corresponding to a corresponding sheet of light-sensitive material of different sensitivity.
Claim 5
Dependent Claim
33 words
In a camera as claimed in claim 3, the further improvement wherein said preselecting means comprise potentiometers which are connected for stepless adjustment of the voltage at a point in the control circuit.
Claim 6
Dependent Claim
23 words
In a camera as claimed in claim 4, the improvement wherein potentiometers are connected with pushbuttons for direct changeover of the pre-adjusted potentiometers.
Claim 7
Dependent Claim
53 words
In a camera as claimed in claim 1, the improvement wherein the light sensitive means is carried by an arm which is pivotally supported at a point outside the image plane in such manner that the light sensor may be moved in a curve into a position above or beneath the image plane.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-22 | 1979-03-24 | 1979-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-22 | 1983-03-24 | 1983-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-22 | 1987-03-24 | 1987-09-23 | $7700.00 | Window Closed / Lapsed |