发明名称 DRIVE METHOD FOR PIEZOELECTRIC TRANSFORMER
摘要 PROBLEM TO BE SOLVED: To control a piezoelectric transformer fully stably and precisely by sweeping the frequency of the drive voltage of a cold-cathode tube discharge lamp from high to low with the piezoelectric transformer until the current of the cold-cathode tube discharge lamp becomes within a set range, and determining the drive frequency of the piezoelectric transformer. SOLUTION: A feedback resistor 109 is connected in series to a cold-cathode tube 108, the voltage corresponding to the current flowing in the cold-cathode tube 108 is detected by a current detecting circuit 110, and it is compared with a set current value I1 by a comparing circuit 111. When the tube current is not within the range of an allowable current value I2 centering on the set current value I1, a control circuit 112 controls a variable oscillating circuit 101 to change the frequency of the drive signal so that the tube current nears the set current value I1. The changed drive signal is waveform-shaped into a sinusoidal wave by a waveform-shaping circuit 102, then it is voltage/current- amplified by a drive circuit 103 and fed to a piezoelectric transformer 104. The output signal is fed to the cold-cathode tube 108 and the feedback resistor 109 and is again detected by the current detecting circuit 110.
申请公布号 JP2000058280(A) 申请公布日期 2000.02.25
申请号 JP19980220042 申请日期 1998.08.04
申请人 MATSUSHITA ELECTRIC IND CO LTD 发明人 MORITOKI KATSUNORI;NAKATSUKA HIROSHI;KAWASAKI OSAMU
分类号 G02F1/133;G05F1/10;H01L41/107;H02M7/48;H05B41/24 主分类号 G02F1/133
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