Light-emitting-element driving circuit
First Claim
1. A light-emitting-element driving circuit which drives a light-emitting element, comprising:
- a voltage boosting circuit unit which boosts a voltage based on a feedback voltage and which supplies a boosted voltage to a first side terminal of the light-emitting element;
a current circuit unit which drives the light-emitting element with a predetermined drive current;
a first feedback loop path through which a voltage on a second side terminal of the light-emitting element is input as the feedback voltage to the voltage boosting circuit unit;
a second feedback loop path which is provided as a backup feedback loop path through which a voltage on the first side terminal of the light-emitting element is input as the feedback voltage to the voltage boosting circuit unit;
an abnormality detection circuit unit which compares the feedback voltage which is input to the voltage boosting circuit unit through the first feedback loop path and a predetermined determination voltage, to detect abnormality in the first feedback loop path; and
a switching circuit unit which switches from the first feedback loop path to the second feedback loop path when the abnormality detection circuit unit has detected the abnormality.
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Accused Products
Abstract
A light-emitting-element driving circuit is provided which comprises a voltage boosting circuit unit which supplies a boosted voltage to a light-emitting element, a current circuit unit which drives the light-emitting element with a current, a normal feedback loop path through which a voltage of the light-emitting element is input as a feedback voltage to the voltage boosting circuit unit, a backup feedback loop path through which a voltage of the light-emitting element is input as the feedback voltage to the voltage boosting circuit unit, an abnormality detection circuit unit which compares the feedback voltage which is input through the normal feedback loop path to the voltage boosting circuit unit and a predetermined determination voltage, to detect abnormality, and a switching circuit which switches from the normal feedback loop path to the backup feedback loop path when the abnormality detection circuit unit has detected the abnormality.
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Citations
4 Claims
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1. A light-emitting-element driving circuit which drives a light-emitting element, comprising:
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a voltage boosting circuit unit which boosts a voltage based on a feedback voltage and which supplies a boosted voltage to a first side terminal of the light-emitting element; a current circuit unit which drives the light-emitting element with a predetermined drive current; a first feedback loop path through which a voltage on a second side terminal of the light-emitting element is input as the feedback voltage to the voltage boosting circuit unit; a second feedback loop path which is provided as a backup feedback loop path through which a voltage on the first side terminal of the light-emitting element is input as the feedback voltage to the voltage boosting circuit unit; an abnormality detection circuit unit which compares the feedback voltage which is input to the voltage boosting circuit unit through the first feedback loop path and a predetermined determination voltage, to detect abnormality in the first feedback loop path; and a switching circuit unit which switches from the first feedback loop path to the second feedback loop path when the abnormality detection circuit unit has detected the abnormality. - View Dependent Claims (2, 3, 4)
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Specification