| 摘要 |
PURPOSE:To decrease the oscillation frequency fluctuation and reduce the energy loss by detecting the output of a light receiving element detecting the lumines cent strength of an electroluminescence element and controlling the on-period of a main switching element. CONSTITUTION:Part of the output light of an electroluminescence loss 10 is inputted to a CdS cell 25, for example, via a slit 28, the voltage detected by this CdS cell 25 is applied to a feedback circuit 26, and the on-period of a main switching element which is a constituting factor of a DC/AC converting circuit 27 is controlled. The fluctuation of the luminescent strength or the oscilla tion frequency due to the aging change of the electroluminescence element is controlled, the switching operation can be reliably performed, thus the energy loss is reduced, the highly efficient drive can be performed, and the brightness of the electroluminescence element can be efficiently adjusted without using a stabilized power supply.
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