Driver circuit and method for driving electroluminescent lamp to emit light at brightness set level
First Claim
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1. A method for driving an electroluminescent lamp to emit light at a brightness set level, comprising the steps of:
- applying a variable bias voltage to the electroluminescent lamp; and
controlling, by a closed loop control, the brightness of the electroluminescent lamp in response to a detected brightness of the electroluminescent lamp, the closed loop control further controlling the brightness in response to the duration of the on-time of the electroluminescent lamp for stabilizing the light intensity of the electroluminescent lamp at the brightness set level during aging of the electroluminescent lamp, wherein said closed loop increases the variable bias voltage in response to a duration of the on-time of the electroluminescent lamp.
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Abstract
A method for driving an electroluminescent lamp to emit light at a brightness set level includes providing a variable bias voltage to the electroluminescent lamp. The variable bias voltage is increased with the duration of the on-time of the electroluminescent lamp. To stabilize the electroluminescent lamp at the brightness set level against aging, a closed loop control of the brightness of the electroluminescent lamp is applied, which is subject to said duration of the on-time the electroluminescent lamp.
23 Citations
13 Claims
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1. A method for driving an electroluminescent lamp to emit light at a brightness set level, comprising the steps of:
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applying a variable bias voltage to the electroluminescent lamp; and
controlling, by a closed loop control, the brightness of the electroluminescent lamp in response to a detected brightness of the electroluminescent lamp, the closed loop control further controlling the brightness in response to the duration of the on-time of the electroluminescent lamp for stabilizing the light intensity of the electroluminescent lamp at the brightness set level during aging of the electroluminescent lamp, wherein said closed loop increases the variable bias voltage in response to a duration of the on-time of the electroluminescent lamp. - View Dependent Claims (2, 3, 4, 5)
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6. An electroluminescent driver circuit for driving an electroluminescent lamp to emit light at a brightness set level, comprising:
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a closed control loop including an electroluminescent lamp brightness detector arranged to detect a brightness of the electroluminescent lamp and generate a lamp brightness signal in response to the detected brightness, and a controllable power supply arranged to generate a variable bias voltage for driving the electroluminescent lamp at the brightness set level in response to said lamp brightness signal;
an on-time detector arranged to detect the total on-time of the electroluminescent lamp and generate therefrom an on-time signal; and
a signal combining circuit arranged to generate an output signal combining the lamp brightness signal and the on-time signal, said controllable power supply increasing the variable bias in response to the on-time signal and receiving said output signal of said signal combining circuit for stabilization of the light intensity of the electroluminescent lamp at the brightness set level during aging of the electroluminescent lamp. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification