Driving circuit for piezoelectric transformer, cold-cathode tube light-emitting apparatus, liquid crystal panel and device with built-in liquid crystal panel
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Abstract
A driving circuit for a piezoelectric transformer is provided, which ensures lighting of all the cold-cathode tubes connected to the piezoelectric transformer, and reduces the difference in brightness between the cathode tubes during steady lighting, thereby enhancing reliability and performance. A plurality of cold-cathode tubes connected to a secondary side of the piezoelectric transformer, and a cold-cathode tube output detector circuit connected in series to a plurality of cold-cathode tubes, for detecting an output state of the respective cold-cathode tubes are provided, and the driving of the piezoelectric transformer is controlled based on a detection signal from the cold-cathode tube output detector circuit. Because of this, the piezoelectric transformer performs the same operation as that with respect to one cold-cathode tube.
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Citations
18 Claims
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1-12. -12. (canceled)
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13. A cold-cathode tube light-emitting apparatus, comprising:
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a piezoelectric transformer including a primary side electrode and a secondary side electrode formed on a piezoelectric body and converting an AC voltage input from the primary side electrode to output the converted AC voltage from the secondary side electrode;
a plurality of cold-cathode tubes connected to a secondary side of the piezoelectric transformer;
a cold-cathode tube output detector portion connected in series to the plurality of cold-cathode tubes, for electrically separating and detecting a current flowing through the respective cold-cathode tubes; and
a control portion for controlling light-emission of the plurality of cold-cathode tubes based on a detection signal from the cold-cathode tube output detector portion. - View Dependent Claims (14, 15, 16, 17)
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18-27. -27. (canceled)
Specification