US3972626A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Autoranging digital luxmeter
Assignee: General Electric Co
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Filing: 1975-06-17
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Granted: 1976-08-03
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Expires: 1995-06-17
Abstract
Abstract An autoranging digital luxmeter is disclosed in which the current from a photocell is converted into a voltage by cascaded, variable gain amplifiers. The output of the amplifiers is coupled by a sample-and-hold circuit to an analogue-to-digital converter, the output of which is a digital representation of lux. The output of the amplifiers is also connected to limit comparison circuitry which, by way of an up-down counter, varies the gain of one or both of the amplifiers.
Inventors
- 👤 Edward L. Laskowsi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:44
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/3084; G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; H03M; H03M1/00; H03M1/12; H03M1/18; H03M1/181; H03M1/183
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
134 words
A digital luxmeter capable of operating on-line with a computer comprising: photocell means for converting incident light into electric current; amplifier means connected to said photocell for converting said current to a voltage, said amplifier means comprising: a first operational amplifier, having first controllable feedback means, connected to said photocell, a second operational amplifier, having second controllable feedback means, connected to the output of said first operational amplifier, and control means connected to said first and second controllable feedback means for varying the feedback of said first and second operational amplifiers; data conversion means coupled to said amplifier means for converting said voltage into a digital representation of said voltage; and range changing means coupled to the output of said amplifier means and to said control means for maintaining said voltage within predetermined limits.
Claim 2
Dependent Claim
134 words
A digital luxmeter capable of operating on-line with a computer comprising: photocell means for converting incident light into electric current; amplifier means connected to said photocell for converting said current to a voltage, said amplifier means comprising: a first operational amplifier, having first controllable feedback means, connected to said photocell, a second operational amplifier, having second controllable feedback means, connected to the output of said first operational amplifier, and control means connected to said first and second controllable feedback means for varying the feedback of said first and second operational amplifiers; data conversion means coupled to said amplifier means for converting said voltage into a digital representation of said voltage; and range changing means coupled to the output of said amplifier means and to said control means for maintaining said voltage within predetermined limits.
Claim 3
Dependent Claim
21 words
The digital luxmeter as set forth in claim 1 and further comprising: means for providing a busy signal during data changes.
Claim 4
Dependent Claim
31 words
The digital luxmeter as set forth in claim 1 and further comprising: digital voltmeter means coupled to the output of said amplifier means for providing a visual readout of incident lux.
Claim 5
Dependent Claim
25 words
The digital luxmeter as set forth in claim 1 wherein the controllable feedback means of said operational amplifiers varies the gain thereof in decade steps.
Claim 6
Dependent Claim
39 words
The digital luxmeter as set forth in claim 4 wherein the gain of said first operational amplifier varies over a range of two steps and the gain of said second operational amplifier varies over a range of one step.
Claim 7
Dependent Claim
21 words
The digital luxmeter as set forth in claim 5 wherein said second operational amplifier has unity gain at its lowest gain.
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) | 1979-08-03 | 1980-02-02 | 1980-08-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-08-03 | 1984-02-02 | 1984-08-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-08-03 | 1988-02-02 | 1988-08-03 | $7700.00 | Window Closed / Lapsed |