| 摘要 |
PURPOSE:To eliminate the need for external clip processing by limiting an input range to a prescribed voltage or below by the dynamic range of as differential amplifier and limiting a converted voltage output into only substantial brightness control range so as to convert the brightness control voltage into a voltage connected easily to a microcomputer or the like. CONSTITUTION:A brightness control voltage is fed to a base of a differential amplifier Q880 and a collector of a transistor (TR) Q880 is connected to a cross point between resistors R832, R833. On the other hand, the collector of the other TR Q879 being a component of the differential amplifier is connected to the resistor R833. A collector voltage of the TR Q879 is connected through an emitter follower TR Q878 and the emitter of the TR Q878 is connected to a terminal 21. Thus, the input voltage is decreased as 5V or below, and a microcomputer or the like is connected directly thereto and abnormality of ABL operation is prevented.
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