Patent US3978370A successfully refreshed from Google Patents.
US3978370A
Expired / Lapsed
US
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Electronic flash unit
Assignee: Robert Bosch GmbH
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Filing: 1974-11-11
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Granted: 1976-08-31
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Expires: 1994-11-11
Abstract
Abstract Operation of the release contact causes a capacitor in the light measuring circuit to be connected to the D.C. supply. The voltage across the capacitor is applied to the gate of a thyristor in the ignition circuit. Only when the voltage across the capacitor has reached a value for proper operation of the exposure control circuit which terminates the flash, is sufficient voltage applied to the gate of the thyristor in the ignition circuit to cause it to fire, thereby causing the flashtube to ignite.
Inventors
- 👤 Albert Stieringer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 07:49
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
102 words
An electronic flash unit comprising, in combination, a flash element; terminating means operative when triggered for terminating a flash being produced by the flash element; a timing circuit operative when activated for measuring the amount of light reflected back toward the unit from objects being illuminated by the unit and when such amount reaches a predetermined value triggering the terminating means; activating means operable for activating the timing circuit; and igniting means for detecting activation of the timing circuit by detecting the occurrence of a predetermined electrical change within the timing circuit and in dependence upon such detection igniting the flash element.
Claim 2
Dependent Claim
102 words
An electronic flash unit comprising, in combination, a flash element; terminating means operative when triggered for terminating a flash being produced by the flash element; a timing circuit operative when activated for measuring the amount of light reflected back toward the unit from objects being illuminated by the unit and when such amount reaches a predetermined value triggering the terminating means; activating means operable for activating the timing circuit; and igniting means for detecting activation of the timing circuit by detecting the occurrence of a predetermined electrical change within the timing circuit and in dependence upon such detection igniting the flash element.
Claim 3
Dependent Claim
79 words
The electronic flash unit defined in claim 1, the timing circuit including energy-storing means operative for receiving and storing electrical energy and for supplying such electrical energy to the remainder of the timing circuit, the activating means comprising means for activating the timing circuit by effecting transfer of energy to the energy-storing means thereof, the igniting means comprising means operative for detecting the accumulation of a predetermined amount of electrical energy by the energy-storing means of the timing circuit.
Claim 4
Dependent Claim
65 words
The electronic flash unit defined in claim 2, the energy-storing means of the timing circuit being a storage capacitor, the means for effecting the transfer of energy to the energy-storing means comprising means for charging the storage capacitor, the means for detecting the accumulation of a predetermined amount of electrical energy by the energy-storing means comprising means responsive to the voltage across the storage capacitor.
Claim 5
Dependent Claim
55 words
The electronic flash unit defined in claim 1, the igniting means including electronic switch means operative when rendered conductive for connecting the flash element to a voltage source, the igniting means furthermore including means for rendering the electronic switch means conductive in dependence upon the detection of the predetermined electrical change within the timing circuit.
Claim 6
Dependent Claim
76 words
The electronic flash unit defined in claim 4, the electronic switch means being comprised of a controllable silicon diode having a control electrode and two main electrodes, connected between the voltage source and the flash element, the means for rendering the electronic switch means conductive comprising means operative for applying a forward-bias voltage to the control electrode of the controllable silicon diode in response to the detection of the predetermined electrical change within the timing circuit.
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) | 1979-08-31 | 1980-03-01 | 1980-08-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-31 | 1984-03-01 | 1984-08-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-31 | 1988-03-01 | 1988-08-31 | $7700.00 | Window Closed / Lapsed |