US3842428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Camera flash controls with internal light detection
Assignee: Pentax Corp
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Filing: 1973-03-05
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Granted: 1974-10-15
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Expires: 1993-03-05
Abstract
Abstract A camera which operates with flash illumination. A flash structure is provided for creating first a preparatory flash illumination, prior to film exposure, and then a main flash illumination during film exposure. Control circuitry is electrically connected with the flash structure for determining the duration of preparatory flash illumination, and an electrical memory structure memorizes an electrical quantity which corresponds to the duration of preparatory flash illumination. Then during main flash illumination a main control structure controls the duration of the main flash illumination in accordance with the electrical quantity stored by the memory structure. Since this latter quantity is determined prior to film exposure, it is possible to measure light during the preparatory flash illumination with an internal photosensitive unit.
Inventors
- 👤 M Kawasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:02
CPC Classifications
G; G03; G03B; G03B15/00; G03B15/02; G03B15/03; G03B15/05; G03B9/00; G03B9/70; G03B2215/00; G03B2215/05
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
103 words
In a camera, flash means for providing first preparatory flash illumination prior to film exposure and then main flash illumination during film exposure, preparatory control means operatively connected with said flash means for controlling the duration of preparatory flash illumination, timing circuit means including memory means operatively connected with said preparatory control means for detecting and storing an electrical quantity representing the time duration of the preparatory flash illumination, and main control means operatively connected with said flash means and with said timing circuit means for determining the duration of main flash illumination at least in part in accordance with said electrical quantity.
Claim 2
Dependent Claim
103 words
In a camera, flash means for providing first preparatory flash illumination prior to film exposure and then main flash illumination during film exposure, preparatory control means operatively connected with said flash means for controlling the duration of preparatory flash illumination, timing circuit means including memory means operatively connected with said preparatory control means for detecting and storing an electrical quantity representing the time duration of the preparatory flash illumination, and main control means operatively connected with said flash means and with said timing circuit means for determining the duration of main flash illumination at least in part in accordance with said electrical quantity.
Claim 3
Dependent Claim
39 words
The combination of claim 1 and wherein the camera has an objective, said preparatory control means including a photosensitive means for receiving light during preparatory flash illumination after the received light has travelled through the objective of the camera.
Claim 4
Dependent Claim
68 words
The combination of claim 2 and wherein said preparatory and main control means respectively include a preparatory flash-terminating means and a main flash-terminating means both of which are operatively connected with said flash means to terminate the operation thereof after the preparatory flash illumination and after the main flash illumination, respectively, so that the flash illumination is interrupted between the preparatory flash illumination and the main flash illumination.
Claim 5
Dependent Claim
25 words
The combination of claim 3 and wherein said flash means includes a single source of flash illumination electrically connected with both of said flash-terminating means.
Claim 6
Dependent Claim
79 words
The combination of claim 2 and wherein said flash means includes a source of flash illumination and said preparatory control means includes a capacitor electrically connected with said source of flash illumination to supply thereto the energy consumed during preparatory flash illumination, so that said capacitor of said preparatory control means discharges during preparatory flash illumination, and said electrical quantity being determined by the length of time during which said capacitor supplies energy to said source of flash illumination.
Claim 7
Dependent Claim
69 words
The combination of claim 2 and wherein said memory is in the form of a memory capacitor for storing a charge corresponding to the time duration of the preparatory flash illumination, said timing circuit means including a time capacitor for retaining a second electrical quantity and a comparing circuit means for comparing said second electrical quantity with said stored electrical quantity to determine the duration of main flash illumination.
Claim 8
Dependent Claim
42 words
The combination of claim 6 and wherein said comparing circuit means is electrically connected with said timing capacitor and said memory capacitor for comparing the charge of the timing capacitor with the memory capacitor to determine the duration of main flash illumination.
Claim 9
Dependent Claim
24 words
The combination of claim 7 and wherein said comparing circuit means Includes a transistor circuit electrically connected with said timing capacitor and memory capacitor.
Claim 10
Dependent Claim
48 words
The combination of claim 2 and wherein said preparatory control means provides for the preparatory flash illumination operating conditions equivalent to those provided by the main control means during main flash illumination, so that the duration of main flash illumination will equal the duration of preparatory flash illumination.
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) | 1977-10-14 | 1978-04-15 | 1978-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-14 | 1982-04-15 | 1982-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-14 | 1986-04-15 | 1986-10-15 | $7700.00 | Window Closed / Lapsed |