Light-emitting element driving device
First Claim
Patent Images
1. A light-emitting element driving device comprising:
- a first control unit adapted to control a drive voltage applied from a voltage source to a light-emitting element;
a second control unit adapted to control a drive current supplied from a current source to said light-emitting element;
a test current supply unit adapted to supply a test current to the light-emitting element when the light-emitting element is switched off; and
a bias voltage setting unit adapted to set a bias voltage applied to the light-emitting element on the basis of a terminal voltage of the light-emitting element supplied with the test current from the test current supply unit when the light-emitting element is switched off, wherein, the first control unit and the second control unit controls an light intensity of a light beam emitted from the light-emitting element.
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Abstract
In a semiconductor laser driving device using a voltage drive system, a drive current of a semiconductor laser is controlled by a drive current control circuit so that a light intensity of light beam emitted from the semiconductor laser is equal to a predetermined light intensity. In a drive voltage control circuit, the drive voltage applied to the semiconductor laser at the time of switching off the semiconductor laser LD is set on the basis of the detected voltage (terminal voltage).
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Citations
18 Claims
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1. A light-emitting element driving device comprising:
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a first control unit adapted to control a drive voltage applied from a voltage source to a light-emitting element;
a second control unit adapted to control a drive current supplied from a current source to said light-emitting element;
a test current supply unit adapted to supply a test current to the light-emitting element when the light-emitting element is switched off; and
a bias voltage setting unit adapted to set a bias voltage applied to the light-emitting element on the basis of a terminal voltage of the light-emitting element supplied with the test current from the test current supply unit when the light-emitting element is switched off, wherein, the first control unit and the second control unit controls an light intensity of a light beam emitted from the light-emitting element. - View Dependent Claims (2, 3)
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4. A light-emitting element driving device for controlling a drive voltage applied from a voltage source to a light-emitting element while controlling a drive current supplied from a current source to the light-emitting element to thereby control an light intensity of a light beam emitted from the light-emitting element, the light-emitting element driving device comprising:
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a bias current supply unit adapted to supply a bias current to the light-emitting element;
a test current supply unit adapted to supply a test current to the light-emitting element when the light-emitting element is switched off;
a bias voltage setting unit adapted to set a bias voltage applied to the light-emitting element on the basis of a terminal voltage of the light-emitting element supplied with the test current from the test current supply unit when said light-emitting element is switched off; and
a bias current setting unit adapted to set the bias current supplied from the bias current supply unit to the light-emitting element on the basis of the bias voltage set by the bias voltage setting unit when the light-emitting element is switched off. - View Dependent Claims (5, 6, 7)
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8. A light-emitting element driving device for controlling a drive voltage applied from a voltage source to a plurality of light-emitting elements while controlling a drive current supplied from a current source to the plurality of light-emitting elements to thereby control the light intensity of light beams emitted from the plurality of light-emitting elements, the light-emitting element driving device comprising:
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a test current supply unit adapted to supply a test current to the light-emitting element when the light-emitting element is switched off;
an arithmetic unit adapted to carry out an arithmetic operation for respective terminal voltages of the plurality of light-emitting elements supplied with the test current from the test current supply unit; and
a bias voltage setting unit for adapted to set a bias voltage applied to the plurality of light-emitting elements on the basis of a voltage value calculated by the arithmetic unit when the plurality of light-emitting elements are switched off. - View Dependent Claims (9, 10, 11)
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12. A light-emitting element driving device for controlling a drive voltage applied from a voltage source to a plurality of light-emitting elements while controlling a drive current supplied from a current source to the plurality of light-emitting elements to thereby control the light intensity of light beams emitted from the plurality of light-emitting elements, the light-emitting element driving device comprising:
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a bias current supply unit adapted to supply bias currents to the plurality of light-emitting elements respectively;
a test current supply unit adapted to supply a test current to the plurality of light-emitting elements when the plurality of light-emitting elements are switched off;
an arithmetic unit adapted to carry out an arithmetic operation for respective terminal voltages of the plurality of light-emitting elements supplied with the test current from the test current supply unit;
a bias voltage setting unit adapted to set a bias voltage applied to the plurality of light-emitting elements on the basis of a voltage value calculated by the arithmetic unit when the plurality of light-emitting elements are switched off; and
a bias current setting unit adapted to set the bias currents supplied from the bias current supply unit to the plurality of light-emitting elements on the basis of the bias voltage set by the bias voltage setting unit when the plurality of light-emitting elements are switched off. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A light-emitting element driving device comprising:
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a first control unit adapted to control a drive voltage applied from a voltage source to a light-emitting element; and
a second control unit adapted to control a drive current supplied from a current source to the light-emitting element, wherein the first control unit and the second control unit controls an light intensity of a light beam emitted from the light-emitting element, wherein the first control unit sets a voltage of the voltage source in accordance with a voltage generated in the light-emitting element as a result of the control of the drive current by the second control unit.
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Specification