US3603799A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light measuring device comprising a plurality of binary circuits for providing a digital representation of photocell output
Assignee: Pentax Corp
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Filing: 1969-03-26
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Granted: 1971-09-07
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Expires: 1989-03-26
Abstract
Abstract A light measuring device includes successive transistor Schmitt triggers having emitter resistors of successively higher resistances, the collector of the input transistor of each trigger being connected through a diode to the emitters of the next successive trigger. A voltage divider includes a photoconductor and resistor series connected across a battery the voltage across the resistor being applied to the Schmitt triggers. The trigger outputs are connected to lamps and may be connected to relay solenoids which control the insertion of resistances in a shutter timing RC network. The photoconductor may control the charging of a capacitor which is coupled through a high impedance input amplifier to the Schmitt trigger inputs.
Inventors
- 👤 Tsukumo Nobusawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 07:10
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/34; H03M1/36; H03M1/361
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
97 words
A light responsive device comprising sensing means including a photocell for providing an output signal in response to the light incident on said photocell, a plurality of successive Schmitt trigger circuits each of which includes a pair of first and second transistors having interconnected emitters, a common emitter resistor, bases and collectors, means connecting the collector of each of said first transistors to the emitters of the transistors of the following switch circuit, means for applying said output signal to the bases of said first transistors, and electric lamps connected to the outputs of said Schmitt circuits.
Claim 2
Dependent Claim
97 words
A light responsive device comprising sensing means including a photocell for providing an output signal in response to the light incident on said photocell, a plurality of successive Schmitt trigger circuits each of which includes a pair of first and second transistors having interconnected emitters, a common emitter resistor, bases and collectors, means connecting the collector of each of said first transistors to the emitters of the transistors of the following switch circuit, means for applying said output signal to the bases of said first transistors, and electric lamps connected to the outputs of said Schmitt circuits.
Claim 3
Dependent Claim
105 words
A light control device comprising a plurality of successive switching networks each switchable between alternative first and second states, means including a photocell for providing an output signal in response to the light incident on said photocell, means for controlling each of said switch networks in response to said output signal and the state of the preceding switch network, a relay solenoid connected to an output of each of said switch networks, a shutter control network including a timing capacitor, a plurality of resistors, and means including switches actuated by said solenoids for alternatively connecting said resistors in a series timing circuit with said capacitor.
Claim 4
Dependent Claim
105 words
A light control device comprising a plurality of successive switching networks each switchable between alternative first and second states, means including a photocell for providing an output signal in response to the light incident on said photocell, means for controlling each of said switch networks in response to said output signal and the state of the preceding switch network, a relay solenoid connected to an output of each of said switch networks, a shutter control network including a timing capacitor, a plurality of resistors, and means including switches actuated by said solenoids for alternatively connecting said resistors in a series timing circuit with said capacitor.
Claim 5
Dependent Claim
94 words
A measuring device comprising a plurality of successive switch networks each switchable between alternative first and second states, a sensing means including a photocell for providing an output signal in response to the light incident on said photocell, each of said switch networks being coupled and responsive to said sensing means output signal and the state of the preceding switching network, a shutter timing network including a timing capacitor and a variable resistor network coupled thereto, and means responsive to the states of said switch networks for controlling the resistance at said resistor network.
Claim 6
Dependent Claim
94 words
A measuring device comprising a plurality of successive switch networks each switchable between alternative first and second states, a sensing means including a photocell for providing an output signal in response to the light incident on said photocell, each of said switch networks being coupled and responsive to said sensing means output signal and the state of the preceding switching network, a shutter timing network including a timing capacitor and a variable resistor network coupled thereto, and means responsive to the states of said switch networks for controlling the resistance at said resistor network.
Claim 7
Dependent Claim
18 words
The measuring device of claim 1 wherein said networks comprise Schmitt trigger circuits having successively different trigger voltages.
Claim 8
Dependent Claim
20 words
The measuring device of claim 4 comprising an electric lamp coupled to the output of each of said Schmitt circuits.
Claim 9
Dependent Claim
81 words
A light measuring device in accordance with claim 3 wherein said switch networks comprise Schmitt circuits each including a pair of first and second transistors having interconnected emitters, a common emitter resistor, bases and collectors, the collector of each of said first transistors being connected to the emitters of the transistors of the following switch network, and the bases of said first transistors being coupled to said sensing means output signal, and electric lamps connected to outputs of said Schmitt circuits.
Claim 10
Dependent Claim
19 words
The light measuring device of claim 6 wherein said emitter resistors of said Schmitt circuits are of different resistances.
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) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |