Patent US4618958A successfully refreshed from Google Patents.
US4618958A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for controlling the radiating output of a semiconductor laser
Assignee: Ricoh Co Ltd
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Filing: 1985-02-08
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Granted: 1986-10-21
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Expires: 2005-02-08
Abstract
Abstract A device detects the radiating output from a semiconductor laser and compares a detected signal with a reference signal in a comparator. An up/down counter is controlled an output signal from the comparator to supply the semiconductor laser with a current proportional to a count output from the up/down counter. The current supplied to the semiconductor laser is controlled and held so as to equalize the input signals to the comparator at all times.
Inventors
- 👤 Isamu Shibata
- 👤 Yoshiaki Kanmoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 13:29
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
121 words
A device for controlling the radiating output of a semiconconductor laser, comprising: (a) a photodetector for detecting the radiating output of the semiconductor laser; (b) a comparator for comparing an output signal from said photodetector with a reference signal; (c) an up/down counter for counting clock signals in a count mode controlled by an output signal from said comparator; (d) a digital-to-analog converter for converting a count output from said up/down counter into an analog signal; (e) a semiconductor laser driver for supplying said semiconductor laser with a current proportional to the analog signal from said digital-to-analog converter; and (f) means for controlling and holding the current supplied to said semiconductor laser to equalize the input signals applied to said comparator.
Claim 2
Independent Claim
121 words
A device for controlling the radiating output of a semiconconductor laser, comprising: (a) a photodetector for detecting the radiating output of the semiconductor laser; (b) a comparator for comparing an output signal from said photodetector with a reference signal; (c) an up/down counter for counting clock signals in a count mode controlled by an output signal from said comparator; (d) a digital-to-analog converter for converting a count output from said up/down counter into an analog signal; (e) a semiconductor laser driver for supplying said semiconductor laser with a current proportional to the analog signal from said digital-to-analog converter; and (f) means for controlling and holding the current supplied to said semiconductor laser to equalize the input signals applied to said comparator.
Claim 3
Dependent Claim
20 words
A device according to claim 1, including means for ceasing the holding of said current supplied to said semiconductor laser.
Claim 4
Independent Claim
142 words
A device for controlling the radiating output of a semiconconductor laser, comprising: (a) a photodetector for detecting the radiating output of the semiconductor laser; (b) a comparator for comparing an output signal from said photodetector with a reference signal; (c) an up/down counter for counting clock signals in a count mode controlled by an output signal from said comparator; (d) a digital-to-analog converter for converting a count output from said up/down counter into an analog signal; (e) a semiconductor laser driver for supplying said semiconductor laser with a current proportional to the analog signal from said digital-to-analog converter; and (f) an edge detector for releasing said up/down counter from a disable mode in response to a timing signal and for disabling said up/down counter in response to the detection of inversion of the output signal from said comparator in a predetermined direction.
Claim 5
Independent Claim
142 words
A device for controlling the radiating output of a semiconconductor laser, comprising: (a) a photodetector for detecting the radiating output of the semiconductor laser; (b) a comparator for comparing an output signal from said photodetector with a reference signal; (c) an up/down counter for counting clock signals in a count mode controlled by an output signal from said comparator; (d) a digital-to-analog converter for converting a count output from said up/down counter into an analog signal; (e) a semiconductor laser driver for supplying said semiconductor laser with a current proportional to the analog signal from said digital-to-analog converter; and (f) an edge detector for releasing said up/down counter from a disable mode in response to a timing signal and for disabling said up/down counter in response to the detection of inversion of the output signal from said comparator in a predetermined direction.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-10-20 | 1990-04-21 | 1990-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-10-20 | 1994-04-21 | 1994-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-10-20 | 1998-04-21 | 1998-10-21 | $7700.00 | Window Closed / Lapsed |