| 摘要 |
PROBLEM TO BE SOLVED: To realize a luminance control making light emitting elements emit light with prescribed luminance at high speed by shortening the delay time of the switching of a constant current source. SOLUTION: A first transistor(Tr) 45 controls the switching between a constant current source 42 and a light emitting element 41 and a second Tr 46 controls the switching between a constant voltage source 44 and the constant current source 42. When a selection signal is inputted from a line control circuit to a gate 45a and the Tr 45 is turned on by the selection signal, the output of the constant current source 42 is conducted o the light emitting element 41. Moreover, the inversion signal of the selection signal from the line control circuit is inputted to a gate 46a via an inverter 47. The input of the first Tr 45 and the input of the second Tr 46 are in a reversal relation each other and when the transistor of one side is turned on, the transistor of other side is made to be turned off complementarily and the output terminal (e) point of the constant current source 42 is made to be always in a conductive state and, thus, a time delay posterior to the changeover between transistors is not present and a prescribed current is made to be instantly conducted to the light emitting element 41.
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