EP0096341A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Laser printer optical system
Assignee: Hitachi Ltd
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Filing: 1983-05-31
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Granted: —
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Expires: 2003-05-31
Abstract
Abstract A laser light source device is disclosed in which the intensity of laser light emitted from a laser diode (1) 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 controll the count mode of an up/down counter (17), and a current for driving the laser diode (1) 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
EP
Data Source
google_patents
Last Synchronized
2026-10-25 22:09
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
135 words
A laser light source device provided with a control circuit for controlling a current supplied to a laser diode (1), said control circuit comprising: a photoelectric transducer (13) for converting the intensity of laser light, emitted from said laser diode (1) into an analog detection signal; a comparator (l6) for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter (17) 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 (19) for converting a digital output signal from said digital up/down counter (17) into an analog output signal; and a current control circuit (2) for controlling a current flowing through said laser diode (1), in accordance with said analog output signal.
Claim 2
Dependent Claim
135 words
A laser light source device provided with a control circuit for controlling a current supplied to a laser diode (1), said control circuit comprising: a photoelectric transducer (13) for converting the intensity of laser light, emitted from said laser diode (1) into an analog detection signal; a comparator (l6) for comparing said analog detection signal with a reference electrical signal to deliver a binary signal; a digital up/down counter (17) 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 (19) for converting a digital output signal from said digital up/down counter (17) into an analog output signal; and a current control circuit (2) for controlling a current flowing through said laser diode (1), in accordance with said analog output signal.
Claim 3
Dependent Claim
43 words
A laser light source device according to Claim 1, wherein said control circuit includes initializing means (17e, 17f, 17g) for loading said digital up/down counter so that said current flowing through said laser diode has a minimum value when power is turned on.
Claim 4
Dependent Claim
29 words
A laser light source device according to Claim 1, wherein said photoelectric transducer (13) is disposed in close vicinity to a light receiving body illuminated with said laser light.
Claim 5
Dependent Claim
23 words
A laser light source device according to Claim 3, wherein said comparator (16) is disposed in close vicinity to said photoelectric transducer (13).
Claim 6
Dependent Claim
47 words
A laser light source device according to Claim 1, wherein said control circuit includes means (17c, 17d) for changing said up-count mode of said digital up/down counter (17) 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
36 words
A laser light source device according to Claim 1, wherein said control circuit includes means (17c, 17h) for generating a maintenance signal when said digital output signal from said digital up/down counter takes a maximum value.
References Cited (Backward Citations)
No citation records indexed.
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