US3714872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photographic flash exposure control system
Assignee: Canon Inc
•
Filing: 1970-04-13
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Granted: 1973-02-06
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Expires: 1990-04-13
Abstract
Abstract A camera system comprises a flash device cooperative with a auto-flash mechanism in a camera. The flash device comprises a capacitor, a power supply circuit for charging the capacitor and a discharge lamp circuit including a discharge lamp. The flash device is further provided with a control circuit connected between the capacitor and the auto-flash mechanism for detecting the charge stored in the capacitor and providing output signal to control the auto-flash mechanism in the camera to obtain the optimum exposure.
Inventors
- 👤 Y Mashimo
- 👤 S Mizui
- 👤 Y Takishima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 04:19
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
81 words
A flash exposure control system for a camera comprising: a capacitor; a power supply circuit coupled to said capacitor for charging said capacitor; a discharge circuit including a discharge lamp coupled to said capacitor; and exposure meter circuit including an exposure meter; and control circuit means operatively coupled between said capacitor and said exposure meter circuit for producing an output control signal for controlling the deflection of said exposure meter in response to variations in the charge stored in said capacitor.
Claim 2
Dependent Claim
81 words
A flash exposure control system for a camera comprising: a capacitor; a power supply circuit coupled to said capacitor for charging said capacitor; a discharge circuit including a discharge lamp coupled to said capacitor; and exposure meter circuit including an exposure meter; and control circuit means operatively coupled between said capacitor and said exposure meter circuit for producing an output control signal for controlling the deflection of said exposure meter in response to variations in the charge stored in said capacitor.
Claim 3
Dependent Claim
81 words
A flash exposure control system for a camera comprising: a capacitor; a power supply circuit coupled to said capacitor for charging said capacitor; a discharge circuit including a discharge lamp coupled to said capacitor; and exposure meter circuit including an exposure meter; and control circuit means operatively coupled between said capacitor and said exposure meter circuit for producing an output control signal for controlling the deflection of said exposure meter in response to variations in the charge stored in said capacitor.
Claim 4
Dependent Claim
81 words
A flash exposure control system for a camera comprising: a capacitor; a power supply circuit coupled to said capacitor for charging said capacitor; a discharge circuit including a discharge lamp coupled to said capacitor; and exposure meter circuit including an exposure meter; and control circuit means operatively coupled between said capacitor and said exposure meter circuit for producing an output control signal for controlling the deflection of said exposure meter in response to variations in the charge stored in said capacitor.
Claim 5
Dependent Claim
41 words
A flash exposure control system as set forth in claim 1, wherein said control circuit means comprises at least one switching element coupled to said capacitor and responsive to a predetermined voltage across said capacitor to produce said output control signal.
Claim 6
Dependent Claim
32 words
A flash exposure control system as set forth in claim 2, wherein said switching element comprises a neon discharge lamp which Conducts when the voltage across said capacitor reaches a predetermined level.
Claim 7
Dependent Claim
57 words
A flash exposure control system as set forth in claim 2, wherein said circuit control means further comprises: photo-coupler means including light emissive means coupled to said switching element, and light responsive means coupled to said exposure meter, said photo-coupler becoming energized in response to the energization of said switching element for producing said output control signal.
Claim 8
Dependent Claim
89 words
A flash exposure control system as set forth in claim 1, wherein said control circuit means comprises: a plurality of switching elements, each connected in parallel with said capacitor for respectively switching to a conductive state in response to mutually different predetermined charge levels of said capacitor; and a plurality of signal conducting means, coupled one each to said plurality of switching elements and to said exposure meter, and each becoming energized in response to the said switching to a conductive state of the respective switch element coupled thereto.
Claim 9
Dependent Claim
51 words
A flash exposure control system as set forth in claim 1, wherein said control circuit means includes a detecting circuit for detecting the voltage across said capacitor, and a voltage source connected to said detecting circuit in an opposed-polarity relationship with respect to the polarity of said voltage across said capacitor.
Claim 10
Dependent Claim
29 words
A flash exposure control system as set forth in claim 1 and further comprising: constant voltage means for providing a constant voltage reference portion of said output control signal.
Claim 11
Dependent Claim
45 words
A flash exposure control system as set forth in claim 1, wherein said control circuit means comprises a photo-coupler including: at least one light emissive means coupled to said capacitor; and light responsive means coupled to said exposure meter for producing said output control signal.
Claim 12
Dependent Claim
75 words
A flash exposure control system as set forth in claim 1, wherein said control circuit means comprises a photo-coupler including: a plurality of light emissive means, and a plurality of resistors, wherein each light emissive means is series connected with a resistor across said capacitor; and a plurality of light responsive means optically coupled respectively to said plurality of light emissive means, and each coupled to said exposure meter for producing said output control signal.
Claim 13
Dependent Claim
51 words
A flash exposure control system for a camera as set forth in claim 1, in which said control circuit means includes diode circuit means for providing a non-linear output control signal for increasing the response range of said exposure meter with respect to said variations in charge stored in said capacitor.
Claim 14
Dependent Claim
63 words
A flash exposure control system for a camera as set forth in claim 1, in which said control circuit means comprises a detecting circuit for detecting the voltage across said capacitor, and semiconductor circuit means coupled between said detecting circuit and said exposure meter for producing said output control signal in response to variations of the said voltage detected by said detecting circuit.
Claim 15
Dependent Claim
49 words
A flash exposure control system for a camera as set forth in claim 11, in which said semiconductor circuit means includes diode circuit means for providing a non-linear output control signal for increasing the response range of said exposure meter with respect to said voltage variations across said capacitor.
Claim 16
Dependent Claim
56 words
A flash exposure control system for a camera as set forth in claim 1, in which said control circuit means includes switching means for applying said output control signal to said exposure meter to control said deflection of said meter to indicate a non-optimum value when said charge on said capacitor is below a predetermined level.
Claim 17
Dependent Claim
44 words
A flash exposure control system for a camera as set forth in claim 13, in which said switching means includes a plurality of voltage sensitive switching devices to control said deflection in steps corresponding to a plurality of predetermined charge levels on said Capacitor.
References Cited (Backward Citations)
US2901671A
Cited
US2946924A
Cited
US3424071A
Cited
US3350604A
Cited
US3470798A
Cited
US3438766A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |