US4228381A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Flash tube apparatus with delayed emission
Assignee: Nikon Corp
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Filing: 1978-10-06
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Granted: 1980-10-14
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Expires: 1998-10-06
Abstract
Abstract A flash tube (speed-light) apparatus is provided with a drive circuit for ionizing gas in the flash tube in response to a triggering voltage produced by a trigger coil, and a light-measuring circuit measures the light emitted by the flash tube and reflected by an object to be photographed and controls the quantity of light emitted by the flash tube. The drive circuit comprises delay means that delays the flash emission by a predetermined delay time commencing with the energizing of the trigger coil. The delay time is selected longer than a period during which the light-measuring circuit is affected by noise generated by the energizing of the trigger coil.
Inventors
- 👤 Hiroshi Hasegawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:13
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
140 words
In flash tube apparatus comprising a drive circuit for ionizing gas in a flash tube by means of a trigger circuit, thereby causing flash discharge in said flash tube, and comprising a light-measuring circuit for measuring the light emitted by said flash tube and reflected by an object to be photographed and for controlling the light emitted by said flash tube, said light-measuring circuit being susceptible to erroneous operation caused by noise generated upon energizing of said trigger circuit, the improvement wherein said drive circuit includes delay means for delaying the flash emission from said flash tube until the lapse of a predetermined delay time commencing with the energizing of said trigger circuit, said delay time being longer than a period during which said light-measuring circuit may be adversely affected by noise generated upon the energizing of said trigger circuit.
Claim 2
Dependent Claim
140 words
In flash tube apparatus comprising a drive circuit for ionizing gas in a flash tube by means of a trigger circuit, thereby causing flash discharge in said flash tube, and comprising a light-measuring circuit for measuring the light emitted by said flash tube and reflected by an object to be photographed and for controlling the light emitted by said flash tube, said light-measuring circuit being susceptible to erroneous operation caused by noise generated upon energizing of said trigger circuit, the improvement wherein said drive circuit includes delay means for delaying the flash emission from said flash tube until the lapse of a predetermined delay time commencing with the energizing of said trigger circuit, said delay time being longer than a period during which said light-measuring circuit may be adversely affected by noise generated upon the energizing of said trigger circuit.
Claim 3
Dependent Claim
30 words
Apparatus in accordance with claim 1, wherein said light-measuring circuit comprises an operational amplifier and a photosensitive element connected between the inverting and non-inverting input terminals of said operational amplifier.
Claim 4
Dependent Claim
35 words
Apparatus in accordance with claim 2, wherein the photosensitive element is a diode and a logarithmic diode is connected between output and input terminals of the amplifier and is bridged by an oppositely poled diode.
Claim 5
Dependent Claim
83 words
Apparatus in accordance with claim 1, wherein said delay means comprises a silicon controlled rectifier connected in series with said flash tube and a delay circuit connected to the gate of said silicon controlled rectifier, said delay circuit being adapted to supply a signal to the gate of said silicon controlled rectifier, thereby rendering the same conductive and thus inducing the flash emission from said flash tube, after the lapse of said predetermined delay time commencing with the energizing of said trigger circuit.
Claim 6
Dependent Claim
39 words
Apparatus in accordance with claim 4, wherein said delay circuit comprises a resistor in series with a capacitor and connected to said trigger circuit so that the capacitor starts charging through said resistor when the trigger circuit is energized.
Claim 7
Dependent Claim
31 words
Apparatus in accordance with claim 5, wherein said delay circuit further comprises a diac connecting the junction of said resistor and said capacitor to the gate of said silicon controlled rectifier.
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) | 1983-10-14 | 1984-04-14 | 1984-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-14 | 1988-04-14 | 1988-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-14 | 1992-04-14 | 1992-10-14 | $7700.00 | Window Closed / Lapsed |