Patent ID: 6188420
Filing Date: 2001-02-13
Classification: B41J,H04N

Abstract:
An image forming apparatus comprising:a photosensitive member;a light-emitting means; said light-emitting means comprising: a light-emitting device array including a plurality of light-emitting devices arranged in the main scanning direction to the moving direction of the photosensitive member; a first transistor array including a plurality of first transistors respectively connected to the light-emitting devices at first terminals of said first transistors, said first transistor array being divided into a plurality of groups comprised of a plurality of transistors; a first line group comprised of a first line connecting commonly to third terminals of each transistor of a first transistor group and a second line connecting commonly to third terminals of each transistor of a second transistor group of said plurality of the divided transistor groups; a second line group comprised of a plurality of lines connecting commonly second terminals of said first transistor and said second transistor of said first transistor group to second terminals of said first transistor and said second transistor of said second transistor group; a capacitor connected to each of the first terminal of said plurality of first transistors respectively, and accumulating electric signals from said second line group; a second transistor array including a plurality of second transistors arranged in a line connecting a capacitor with light-emitting devices by first terminals and second terminals; and a third line connecting commonly third terminals of second transistors, wherein the first, second and third terminals of said first and second transistors are drain terminals, source terminals and gate terminals, respectively; anda driving means for driving said light-emitting circuit, applying scanning signals sequentially to said first line group, whereby third terminals of first transistors on the lines applied by said scanning signals are switched on, during which condition third terminals of second transistors are switched off by the third line, and a voltage signal is applied to the second line group in response to an image signal, whereby third terminals of second transistors are switched on by the third line after said voltage signal is charged and accumulated in a capacitor, whereby electric signal held in said capacitor is discharged to the light-emitting devices simultaneously.