US4580044A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser apparatus with control circuit for stabilizing laser output
Assignee: Hitachi Ltd
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Filing: 1983-06-01
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Granted: 1986-04-01
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Expires: 2003-06-01
Abstract
Abstract A laser light source device in which the intensity of laser light emitted from a laser diode is detected, the detected value of the light intensity is compared with a predetermined value to generate a binary signal, the binary signal is used to control the count mode of an up/down counter, and a current for driving the laser diode is controlled on the basis of the output of the up/down counter, to prevent the intensity of laser light from decreasing.
Inventors
- 👤 Jinichi Hongo
- 👤 Shoichi Ito
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 04:56
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
156 words
A laser light source device provided with a control circuit for controlling a current supplied to a laser diode, said control circuit comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and means for changing said up-count mode of said digital up/down counter over to said down-count mode when said digital output signal from said digital up/down counter takes a maximum value.
Claim 2
Dependent Claim
156 words
A laser light source device provided with a control circuit for controlling a current supplied to a laser diode, said control circuit comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and means for changing said up-count mode of said digital up/down counter over to said down-count mode when said digital output signal from said digital up/down counter takes a maximum value.
Claim 3
Dependent Claim
34 words
A laser light source device according to claim 1, wherein said control circuit includes means for generating a maintenance signal when said digtial output signal from said digital up/down counter takes a maximum value.
Claim 4
Dependent Claim
181 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said control circuit comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up/count mode and a down/count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; initializing means for loading said digital up/down counter so that said current flowing through said laser diode has a minimum value when power applied to the apparatus is turned on; and signal generating means for delivering one sampling clock signal to said digital up/down counter for each binary signal delivered from said comparator to said digital up/down counter.
Claim 5
Dependent Claim
181 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said control circuit comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up/count mode and a down/count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; initializing means for loading said digital up/down counter so that said current flowing through said laser diode has a minimum value when power applied to the apparatus is turned on; and signal generating means for delivering one sampling clock signal to said digital up/down counter for each binary signal delivered from said comparator to said digital up/down counter.
Claim 6
Dependent Claim
42 words
A laser apparatus according to claim 3, wherein said control circuit includes means for changing said up/count mode of said digital up/down counter over to said down/count mode when said digital output signal from said digital up/down counter takes a maximum value.
Claim 7
Dependent Claim
32 words
A laser apparatus according to claim 3, wherein said control circuit includes means for generating a maintenance signal when said digital output signal from said digital up/down counter takes a maximum value.
Claim 8
Dependent Claim
187 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said laser apparatus adapted for scanning laser light to form an exposed region on a photoconductive surface, comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal, said photoelectric transducer being disposed on an extension line of a laser scanning line; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and wherein said control circuit includes means for changing said up-count mode of said digital up/down counter over to said down-count mode when said digital output signal from said digital up/down counter takes a maximum value.
Claim 9
Dependent Claim
187 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said laser apparatus adapted for scanning laser light to form an exposed region on a photoconductive surface, comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal, said photoelectric transducer being disposed on an extension line of a laser scanning line; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and wherein said control circuit includes means for changing said up-count mode of said digital up/down counter over to said down-count mode when said digital output signal from said digital up/down counter takes a maximum value.
Claim 10
Dependent Claim
32 words
A laser apparatus according to claim 6, wherein said control circuit includes means for generating a maintenance signal when said digital output signal from said digital up/down counter takes a maximum value.
Claim 11
Dependent Claim
215 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said laser apparatus adapted for scanning laser light to form an exposed region on a photoconductive surface, comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal, said photoelectric transducer being disposed on an extension line of a laser scanning line; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and wherein said control circuit includes initializing means for loading said digital up/down counter so that said current flowing through said laser diode has a minimum value when power applied to said apparatus is turned on, and signal generating means for delivering one sampling clock signal to said digital up/down counter for each binary signal delivered by said comparator to said digital up/down counter.
Claim 12
Dependent Claim
215 words
A laser apparatus provided with a control circuit for controlling a current supplied to a laser diode, said laser apparatus adapted for scanning laser light to form an exposed region on a photoconductive surface, comprising: a photoelectric transducer for converting the intensity of laser light emitted from said laser diode into an analog detection signal, said photoelectric transducer being disposed on an extension line of a laser scanning line; a comparator for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter applied with said binary signal to change over from one of an up-count mode and a down-count mode to the other; a digital-to-analog converter for converting a digital output signal from said digital up/down counter into an analog output signal; a current control circuit for controlling a current flowing through said laser diode, in accordance with said analog output signal; and wherein said control circuit includes initializing means for loading said digital up/down counter so that said current flowing through said laser diode has a minimum value when power applied to said apparatus is turned on, and signal generating means for delivering one sampling clock signal to said digital up/down counter for each binary signal delivered by said comparator to said digital up/down counter.
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) | 1989-03-31 | 1989-09-30 | 1990-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-03-31 | 1993-09-30 | 1994-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-03-31 | 1997-09-30 | 1998-04-01 | $7700.00 | Window Closed / Lapsed |