US4112443A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Shutter and low-light indicator actuating device for a camera
Assignee: Ricoh Co Ltd
•
Filing: 1977-01-21
•
Granted: 1978-09-05
•
Expires: 1997-01-21
Abstract
Abstract Voltage comparators for actuating a camera shutter and a low-light indicating lamp respectively have inputs connected to junctions of photocells and resistors so as to be controlled in response to sensed light level. The voltage comparator for the low-light indicator energizes the indicator lamp when the light level is below a low-light value from the time the shutter release button is partially depressed until the time the shutter is closed after the exposure. The voltage comparator for the shutter produces a shutter opening signal to open the shutter for the required length of time based on the light level. The output of the voltage comparator for the shutter is connected to a stroke input of the voltage comparator for the low-light indicator so that the low light indicator is de-energized when the shutter is closed.
Inventors
- 👤 Susumi Iguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:06
CPC Classifications
G; G03; G03B; G03B17/00; G03B17/18; G03B17/20; G03B7/00; G03B7/08; G03B7/081; G03B7/083; G03B2217/00; G03B2217/005
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
250 words
A shutter and low-light indicator actuating device comprising: a D.C. voltage source; light sensitive shutter actuator means powered by the voltage source for producing an electric shutter opening signal for a length of time corresponding to the sensed light level; light sensitive low-light sensor means connected directly across the voltage source for producing an electric signal analogous to the sensed level; and comparator means connected to the low-light sensor means and the shutter actuator means for producing an electric indicator activating signal only while the electrical signal produced by the low-light sensor means corresponds to a sensed light level below a predetermined value and the shutter opening signal is produced by the shutter actuator means; the comparator means comprising an indicator current switching transistor, the shutter actuator means being connected to a base of the switching transistor, and a voltage comparator transistor, a base of the comparator transistor being connected to the low-light sensor means and a collector circuit of the comparator transistor being connected between the base of the switching transistor and the voltage source in such a manner that the comparator transistor is turned off while the electric signal produced by the low-light sensor means corresponds to a sensed light level below the predetermined value and turned on thereby connecting the base of the switching transistor to the voltage source with a polarity to turn off the switching transistor while the electric signal produced by the low-light sensor corresponds to a sensed light level above the predetermined value.
Claim 2
Dependent Claim
250 words
A shutter and low-light indicator actuating device comprising: a D.C. voltage source; light sensitive shutter actuator means powered by the voltage source for producing an electric shutter opening signal for a length of time corresponding to the sensed light level; light sensitive low-light sensor means connected directly across the voltage source for producing an electric signal analogous to the sensed level; and comparator means connected to the low-light sensor means and the shutter actuator means for producing an electric indicator activating signal only while the electrical signal produced by the low-light sensor means corresponds to a sensed light level below a predetermined value and the shutter opening signal is produced by the shutter actuator means; the comparator means comprising an indicator current switching transistor, the shutter actuator means being connected to a base of the switching transistor, and a voltage comparator transistor, a base of the comparator transistor being connected to the low-light sensor means and a collector circuit of the comparator transistor being connected between the base of the switching transistor and the voltage source in such a manner that the comparator transistor is turned off while the electric signal produced by the low-light sensor means corresponds to a sensed light level below the predetermined value and turned on thereby connecting the base of the switching transistor to the voltage source with a polarity to turn off the switching transistor while the electric signal produced by the low-light sensor corresponds to a sensed light level above the predetermined value.
Claim 3
Dependent Claim
41 words
An actuating device as in claim 1, in which the comparator means has a signal input and a strobe input, the low-light sensor means being connected to the signal input and the shutter actuator means being connected to the strobe input.
Claim 4
Dependent Claim
44 words
An actuating device as in claim 1, in which the low-light sensor means comprises a light sensitive resistance element and a resistor connected in series across the voltage source, a junction of the resistance element and the resistor being connected to the comparator means.
Claim 5
Dependent Claim
26 words
An actuating device as in claim 1, further comprising a shutter actuated switch for actuating the shutter actuator means to produce the electric shutter opening signal.
References Cited (Backward Citations)
US3664245A
Cited
US4027314A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-09-04 | 1982-03-06 | 1982-09-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-09-04 | 1986-03-06 | 1986-09-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-09-04 | 1990-03-06 | 1990-09-05 | $7700.00 | Window Closed / Lapsed |