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US 7,402,962 B1Granted
System and methods of driving an electroluminescent lamp
AssigneePacificTech Microelectronics, Inc.
InventorVincent Lok-Cheung Fong
Life of this patent
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Abstract
Embodiments of the present invention include systems and methods of driving an electroluminescent lamp. In one embodiment, the electroluminescent lamp is driven to a first threshold during a first time period and then driven to successive voltages between the threshold and a maximum voltage during successive time. This method of driving the lamp waveshapes the lamp voltage signal. In one example, the thresholds are set to minimize audible noise from the electroluminescent lamp due to the piezoelectric effect.
Claims12
An electronic circuit comprising:
- an electroluminescent lamp having a first terminal and a second terminal;
- a regulator having a first input coupled to an input voltage, an output for providing an output voltage, and a feedback input;
- a programmable feedback circuit having a first input coupled to the output of the regulator, an output coupled to the feedback input of the regulator to provide a feedback voltage, and a control input for programming a relationship between the regulator output voltage and the feedback voltage;
- and
- a driver circuit having a first control input, a first output coupled to the first terminal of the lamp, and a second output coupled to the second terminal of the lamp,
- wherein during a first time period, the feedback circuit is programmed to increase a voltage across said electroluminescent lamp to a first threshold and then hold the voltage across said electroluminescent lamp constant,
- wherein during one or more successive time periods, the feedback circuit is reprogrammed to successively increase the voltage across said electroluminescent lamp and then hold the voltage across said electroluminescent lamp constant, and
- wherein during a final time period, the feedback circuit is reprogrammed to increase a voltage across said electroluminescent lamp to a maximum voltage and then hold the voltage across said electroluminescent lamp constant.
5 more elements
A method of driving an electroluminescent lamp comprising:
- during a first time period, increasing a voltage across said electroluminescent lamp to a first threshold and then holding the voltage across said electroluminescent lamp constant;
- during one or more successive time periods, successively increasing the voltage across said electroluminescent lamp and then holding the voltage across said electroluminescent lamp constant;
- and
- during a final time period, increasing a voltage across said electroluminescent lamp to a maximum voltage and then holding the voltage across said electroluminescent lamp constant.
1 more element
Dependencies are inferred from the claim text.