LIGHT EMITTING ELEMENT DRIVE DEVICE
First Claim
1. A light emitting element drive device, comprising:
- a light emitting unit that includes a light emitting element and that performs dimming based on a pulse width modulation (PWM) signal;
a first switching element that is turned ON or OFF based on the PWM signal and that is connected in series with the light emitting unit; and
a protection circuit that includes a charging circuit and a second switching element,wherein the second switching element is turned ON when a first voltage obtained by a charging operation of the charging circuit is equal to or more than a first predetermined value,the charging circuit discharges electric charge through the first switching element when a second voltage between input and output terminals of the first switching element drops, andthe first switching element is turned OFF despite existence of the PWM signal when the second switching element is turned ON.
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Accused Products
Abstract
A light emitting element drive device includes a light emitting unit that includes a light emitting element and that performs dimming based on a pulse width modulation (PWM) signal, a first switching element that is turned ON or OFF based on the PWM signal and that is connected in series to the light emitting unit, and a protection circuit that includes a charging circuit and a second switching element. The second switching element is turned ON when a first voltage obtained by a charging operation of the charging circuit is equal to or more than a first predetermined value. The charging circuit discharges electric charge through the first switching element when a second voltage between input and output terminals of the first switching element drops. The first switching element is turned OFF despite the existence of the PWM signal when the second switching element is turned ON.
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Citations
10 Claims
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1. A light emitting element drive device, comprising:
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a light emitting unit that includes a light emitting element and that performs dimming based on a pulse width modulation (PWM) signal; a first switching element that is turned ON or OFF based on the PWM signal and that is connected in series with the light emitting unit; and a protection circuit that includes a charging circuit and a second switching element, wherein the second switching element is turned ON when a first voltage obtained by a charging operation of the charging circuit is equal to or more than a first predetermined value, the charging circuit discharges electric charge through the first switching element when a second voltage between input and output terminals of the first switching element drops, and the first switching element is turned OFF despite existence of the PWM signal when the second switching element is turned ON. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A light emitting element drive device, comprising:
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a light emitting unit that includes a light emitting element and that performs dimming based on a pulse width modulation (PWM) signal; a switching element that is turned ON or OFF based on the PWM signal and that is connected in series with the light emitting unit; and a protection circuit that times a period for which a voltage between input and output terminals of the switching element is maintained as a voltage value that is equal to or more than a first predetermined value, wherein the protection circuit provides an OFF signal to the switching element so as to turn off the switching element when the period is equal to or more than a second predetermined value, and the switching element is turned OFF despite existence of the PWM signal when the switching element receives the OFF signal. - View Dependent Claims (10)
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Specification