Patent EP0413449A2 successfully refreshed from Google Patents.
Patent EP0235813A2 successfully refreshed from Google Patents.
EP0235813A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Circuit for driving a laser diode
Assignee: Citizen Watch Co Ltd
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Filing: 1987-03-04
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Granted: —
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Expires: 2007-03-04
Abstract
Abstract A driving circuit has an exciting circuit (44) for intermittently exciting the laser diode (30). A photodiode (28) is provided for detecting the power of beam emitted from the laser diode, and a resistor (32) is connected to the photodiode in series. Voltage across the resistor is stored in a capacitor (36) of a charging circuit. The charged voltage is applied to a constant current circuit (24) to control a current supplying to the laser diode to stabilize the power of beam of the laser diode.
Inventors
- 👤 Nobuyuki Hashimoto
- 👤 Kazuya Ohike
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 21:53
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06835
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
80 words
A circuit for driving a laser diode having an exciting circuit (44) for exciting the laser diode (30), a photodiode (28) for detecting the power of beam emitted from the laser diode, characterized in that the circuit comprises a resistor (32) connected to the photodiode in series, a charging circuit (36) for charging voltage across the resistor, and a constant current circuit (24) responsive to the voltage charged in the charging circuit for supplying constant current to the laser diode.
Claim 2
Dependent Claim
80 words
A circuit for driving a laser diode having an exciting circuit (44) for exciting the laser diode (30), a photodiode (28) for detecting the power of beam emitted from the laser diode, characterized in that the circuit comprises a resistor (32) connected to the photodiode in series, a charging circuit (36) for charging voltage across the resistor, and a constant current circuit (24) responsive to the voltage charged in the charging circuit for supplying constant current to the laser diode.
Claim 3
Dependent Claim
30 words
The circuit according to claim 1 wherein the exciting circuit comprises a transistor connected to the laser diode in parallel and arranged to be intermittently turned on by clock pulses.
Claim 4
Dependent Claim
25 words
The circuit according to claim 1 wherein the charging circuit includes a capacitor and a diode which are arranged to form a one-way charging circuit.
Claim 5
Dependent Claim
53 words
The circuit according to claim 1 wherein the constant current circuit includes an operational amplifier applied with the voltage charged in the charging circuit and a transistor connected to the laser diode in series and operative to an output voltage of the operational amplifier to control the current flowing in the laser diode.
Claim 6
Dependent Claim
17 words
The circuit according to claim 1 further comprising an inductor connected to the laser diode in series.
Claim 7
Dependent Claim
22 words
The circuit according to claim 1 further comprising a resistor for deciding a time constant for the discharge of the charging circuit.
Claim 8
Dependent Claim
21 words
The circuit according to claim 4 wherein the operational amplifier has a negative feedback circuit comprising a capacitor and a resistor.
Claim 9
Dependent Claim
25 words
The circuit according to claim 7 wherein the charging circuit includes a capacitor and a diode which are arranged to form a one-way charging circuit.
References Cited (Backward Citations)
No citation records indexed.
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