US3581643A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light measuring device
Assignee: Yashica Co Ltd
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Filing: 1968-04-29
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Granted: 1971-06-01
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Expires: 1988-04-29
Abstract
Abstract A light measuring device includes a photoconductor and variable resistor series connected to a battery. The voltage across the variable resistor is applied to the input of a pair of amplifiers each of which includes an input switching transistor having emitter and collector resistors, and an output transistor with an output energizing a signal lamp. Another transistor has its input connected between the switching transistor collectors and its output to a third lamp. The ratio of the resistances of the collector and emitter resistors are different so that the switching transistor stages respond to different level signals and the output transistors are of opposite types.
Inventors
- 👤 Hirofumi Yoshimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 12:12
CPC Classifications
G; G03; G03B; G03B17/00; G03B17/18; G03B17/20; G01; G01J; G01J1/00; G01J1/42; G01J1/44
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
61 words
A light measuring device comprising a photoresponsive element, control means including first and second amplifiers oppositely responsive to said photoresponsive element and first and second means biasing said first and second amplifiers respectively to different signal response points, and first and second electric lamps concurrently coupled to and energized in response to the outputs of said first and second amplifiers respectively.
Claim 2
Dependent Claim
61 words
A light measuring device comprising a photoresponsive element, control means including first and second amplifiers oppositely responsive to said photoresponsive element and first and second means biasing said first and second amplifiers respectively to different signal response points, and first and second electric lamps concurrently coupled to and energized in response to the outputs of said first and second amplifiers respectively.
Claim 3
Dependent Claim
28 words
The light measuring device of claim 1 comprising a camera viewing system including an eyepiece, and means for concurrently observing said first and second lamps through said eyepiece.
Claim 4
Dependent Claim
48 words
The light measuring device of claim 1, wherein said photoresponsive element comprises a photoconductor and said control means includes a source of current and a variable resistor connected in seriEs with said photoconductor to said current source, said amplifiers having a common input defined by said variable resistor.
Claim 5
Dependent Claim
26 words
The light measuring device of claim 3 wherein the outputs of said amplifiers are of opposite phase and connected to said first and second lamps respectively.
Claim 6
Dependent Claim
124 words
A light measuring device comprising a photoconductor, control means including a source of current, a variable resistor connected in series with said photoconductor to said source of current, and first and second amplifiers differently responsive to said photoconductor and each including a similar switching transistor having its collector and emitter connected to corresponding collector and emitter resistors, and its base connected through said variable resistor and a respective emitter resistor, in series, to said emitter, the ratio of the resistance of the collector resistor to that of the emitter resistor of each of said transistors being different whereby said amplifiers respond to different input signals, and first and second electric lamps energized in response to the outputs of said first and second amplifiers respectively.
Claim 7
Dependent Claim
124 words
A light measuring device comprising a photoconductor, control means including a source of current, a variable resistor connected in series with said photoconductor to said source of current, and first and second amplifiers differently responsive to said photoconductor and each including a similar switching transistor having its collector and emitter connected to corresponding collector and emitter resistors, and its base connected through said variable resistor and a respective emitter resistor, in series, to said emitter, the ratio of the resistance of the collector resistor to that of the emitter resistor of each of said transistors being different whereby said amplifiers respond to different input signals, and first and second electric lamps energized in response to the outputs of said first and second amplifiers respectively.
Claim 8
Dependent Claim
43 words
The light measuring device of claim 5 wherein said amplifiers include opposite types output transistors each having a base connected to the output of a respective switching transistor and an output connected in series with a respective lamp to said source of current.
Claim 9
Dependent Claim
39 words
The light measuring device of claim 5 comprising a third lamp and a transistor having a base and emitter connected to respective collectors of said switching transistors, and a collector connected through said third lamp to said current source.
Claim 10
Dependent Claim
19 words
The light measuring device of claim 1 including means for adjustably attentuating the light incident on said photosensitive element.
Claim 11
Dependent Claim
18 words
The light measuring device of claim 1 including differently colored light filters positioned in front of said lamps.
Claim 12
Dependent Claim
67 words
A light measuring device comprising a photoresponsive element, control means including first and second amplifiers differently responsive to said photoresponsive element, first and second electric lamps energized in response to the outputs of said first and second amplifiers respectively, a third amplifier responsive to a difference in the states of said first and second amplifiers, and a third electric lamp energized in response to said third amplifier.
Claim 13
Dependent Claim
67 words
A light measuring device comprising a photoresponsive element, control means including first and second amplifiers differently responsive to said photoresponsive element, first and second electric lamps energized in response to the outputs of said first and second amplifiers respectively, a third amplifier responsive to a difference in the states of said first and second amplifiers, and a third electric lamp energized in response to said third amplifier.
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) | 1974-05-31 | 1974-11-30 | 1975-06-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-05-31 | 1978-11-30 | 1979-06-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-05-31 | 1982-11-30 | 1983-06-01 | $7700.00 | Window Closed / Lapsed |