Patent US3263946A successfully refreshed from Google Patents.
US5084887A
Expired / Lapsed
US
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Driving device for semiconductor laser
Assignee: Brother Industries Ltd
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Filing: 1991-03-05
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Granted: 1992-01-28
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Expires: 2011-03-05
Abstract
Abstract A driving device for stimulating light emission of a semiconductor laser, comprises a driving circuit for applying the semiconductor laser to a pumping signal including a biasing current and a modulated signal to emit laser light from the laser source, a photosensor for detecting the laser light and outputting a detection signal representing light amount of the detected laser light, a compensating unit comprising a comparator and an integrating circuit for generating a binary-coded biasing signal for producing the biasing current while compensating fluctuation of the threshold current of the semiconductor laser on the basis of the detected signal from the photosensor every predetermined period, an adding circuit for adding the biasing signal of the compensating unit to the input modulated signal and outputting the added signals therefrom, and a constant-current circuit for generating a predetermined constant current. The constant current of the constant-current generating unit and the added signals of the adding unit are added to each other and supplied to the semiconductor laser as the pumping signal.
Inventors
- 👤 Tsuyoshi Ohashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:24
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06832; H04; H04N; H04N1/00; H04N1/024; H04N1/032; H04N1/036
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
179 words
A driving device for stimulating light emission of a laser source having a threshold current for the light emission with a pumping signal including a biasing current and an input modulated signal, comprising: a driving unit for applying the laser source to the pumping signal to emit laser light from the laser source; a photodetecting unit for detecting the laser light and outputting a detection signal representing light amount of the detected laser light; a compensating unit for generating a binary-coded biasing signal for producing the biasing current while compensating fluctuation of the threshold current of the laser source on the basis of the detected signal from said photodetecting unit every predetermined period; an adding unit for adding the biasing signal of said compensating unit to the input modulated signal and outputting the added signals therefrom; and a constant-current generating unit for generating a predetermined constant current, wherein the constant current of said constant-current generating unit and the added signals of said adding unit are added to each other and supplied to the laser source as the biasing signal.
Claim 2
Dependent Claim
179 words
A driving device for stimulating light emission of a laser source having a threshold current for the light emission with a pumping signal including a biasing current and an input modulated signal, comprising: a driving unit for applying the laser source to the pumping signal to emit laser light from the laser source; a photodetecting unit for detecting the laser light and outputting a detection signal representing light amount of the detected laser light; a compensating unit for generating a binary-coded biasing signal for producing the biasing current while compensating fluctuation of the threshold current of the laser source on the basis of the detected signal from said photodetecting unit every predetermined period; an adding unit for adding the biasing signal of said compensating unit to the input modulated signal and outputting the added signals therefrom; and a constant-current generating unit for generating a predetermined constant current, wherein the constant current of said constant-current generating unit and the added signals of said adding unit are added to each other and supplied to the laser source as the biasing signal.
Claim 3
Dependent Claim
77 words
A driving device as claimed in claim 1, wherein said compensating unit comprises a comparing unit for comparing the detection signal with a predetermined reference level to output a comparison signal having a predetermined level when the detection signal is lower than the reference level, and an integrating unit for integrating the comparison signal for a period when the detection signal is lower than the reference level to output an integrated result as a binary-coded biasing signal.
Claim 4
Dependent Claim
44 words
A driving device as claimed in claim 2, wherein said compensating unit further comprises an AND gate for passing the comparision signal from said comparing unit therethrough to said integrating unit for a period when the detection signal is lower than the reference level.
Claim 5
Dependent Claim
20 words
A driving device as claimed in claim 2, wherein said integrating unit comprises a clock generator and an up-and-down counter.
Claim 6
Dependent Claim
30 words
A driving device as claimed in claim 1, wherein the predetermined constant current is a current lower than a threshold current of the semiconductor laser at a minimum permissible temperature.
Claim 7
Dependent Claim
16 words
A driving device as claimed in claim 1, wherein the laser source comprises a semiconductor laser.
References Cited (Backward Citations)
US4689795A
Cited
US4768198A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-01-27 | 1995-07-29 | 1996-01-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-01-27 | 1999-07-29 | 2000-01-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-01-27 | 2003-07-29 | 2004-01-28 | $7700.00 | Window Closed / Lapsed |