US3643100A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photocell circuit for providing indications of both available light and flashbulb readiness
Assignee: Agfa Gevaert AG
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Filing: 1970-02-19
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Granted: 1972-02-15
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Expires: 1990-02-19
Abstract
Abstract Operational readiness of a flashbulb is indicated by an indicator lamp prior to release of the camera shutter by connecting the flashbulb with a series resistor in the baseemitter circuit of a transistor, whose collector circuit contains the indicator lamp. By a suitable switching arrangement, the circuit may be combined with the camera automatic exposure control circuit. The condition of the battery and the light conditions affecting the exposure may also be tested.
Inventors
- 👤 Dieter Engelsmann
- 👤 Hubert Hackenberg
- 👤 Johann Putscher
- 👤 Rolf Strittmatter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 01:05
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325; G; G03; G03B; G03B43/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
166 words
Arrangement for indicating the operational readiness of light flash generating means associated with a photographic camera having a release contact for initiating a light flash by said light flash generating means, comprising, in combination, a switching element having an input circuit and an output circuit; a voltage source for energizing said switching element; indicator means connected to said output circuit; connecting means connecting said light flash generating means to said input circuit in such a manner that the indication of said indicator means prior to activation of said release contact in said camera depends upon the operational state of said light flash generating means; photosensitive means mounted to receive light reflected from the object to be photographed; resistor means connected in series with said light flash generating means; and a selector switch means for connecting said photosensitive element in parallel with said light flash generating means and said resistor means in a first selector position, whereby said indicator means also furnish an indication of available light.
Claim 2
Dependent Claim
166 words
Arrangement for indicating the operational readiness of light flash generating means associated with a photographic camera having a release contact for initiating a light flash by said light flash generating means, comprising, in combination, a switching element having an input circuit and an output circuit; a voltage source for energizing said switching element; indicator means connected to said output circuit; connecting means connecting said light flash generating means to said input circuit in such a manner that the indication of said indicator means prior to activation of said release contact in said camera depends upon the operational state of said light flash generating means; photosensitive means mounted to receive light reflected from the object to be photographed; resistor means connected in series with said light flash generating means; and a selector switch means for connecting said photosensitive element in parallel with said light flash generating means and said resistor means in a first selector position, whereby said indicator means also furnish an indication of available light.
Claim 3
Dependent Claim
16 words
An arrangement as set forth in claim 1, wherein said indicator means are an indicator lamp.
Claim 4
Dependent Claim
40 words
An arrangement as set forth in claim 1, further comprising a single-throw switch means connecting said voltage source to said switching element when in a first state, and disconnecting said voltage source from said switching element in a second state.
Claim 5
Dependent Claim
47 words
An arrangement as set forth in claim 3, wherein said switching element is part of an exposure control circuit of said photographic camera; and wherein said indicator means are the indicator lamp used to indicate the sufficiency of available light for an exposure by said photographic camera.
Claim 6
Dependent Claim
65 words
An arrangement as set forth in claim 4, wherein said exposure control circuit comprises a timing circuit, and shutter-operating means; first switching means for alternatively connecting said timing circuit or said light flash generating means to said input circuit of said switching element; and second switching means for alternatively connecting said shutter-operating means or said indicator means to said output circuit of said switching element.
Claim 7
Dependent Claim
72 words
An arrangement as set forth in claim 5, wherein said switching element is a transistor; wherein said timing circuit comprises a photoresisTance mounted to receive light available for a photographic exposure; a capacitor connected in series with said photoresistance, the base of said transistor being connected to the common point of said photoresistance and said capacitor; and wherein said shutter-operating means comprise a magnetic coil connected to the collector of said transistor.
Claim 8
Dependent Claim
51 words
An arrangement as set forth in claim 1, further comprising a second resistor connected in parallel with said light flash generating means and said resistor when said selector switch is in a second selector position, whereby the indication on said indicator means depends upon the voltage furnished by said voltage source.
Claim 9
Dependent Claim
26 words
An arrangement as set forth in claim 7, further comprising means for preventing the simultaneous operation of said light flash generating means and said indicator means.
Claim 10
Dependent Claim
70 words
An arrangement as set forth in claim 8, wherein said means for preventing the simultaneous operation of said light flash generating means and said indicator means comprise a delay capacitor; and third switching means for connecting said delay capacitor parallel with said light flash generating means and said resistor, whereby operation of said indicator means is delayed for a time interval depending upon the charging time of said delay capacitor.
Claim 11
Dependent Claim
42 words
An arrangement as set forth in claim 9, wherein said third switching means are mechanically coupled to said release contact, for connecting said delay capacitor in parallel with said light flash generating means and said resistor upon activation of said release contact.
Claim 12
Dependent Claim
78 words
An arrangement as set forth in claim 10, wherein said switching element is a transistor having a base, emitter, and collector; wherein said delay capacitor is connected between said base and said emitter of said transistor by said third switching means upon activation of said release contact, whereby said transistor becomes conductive upon attainment of a predetermined minimum of resistance between the terminals of said light flash generating means, and a predetermined minimum charge upon said delay capacitor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-14 | 1975-08-16 | 1976-02-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-14 | 1979-08-16 | 1980-02-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-14 | 1983-08-16 | 1984-02-15 | $7700.00 | Window Closed / Lapsed |