Optical print head and image forming apparatus

摘要

An optical print head includes: light-emitting elements in line shape; first power line supplying first reference voltage; second power line supplying drive current to each light-emitting element and supplying second reference voltage; DAC outputting first voltage indicating light emission amount of each light-emitting element; first elements for holding first voltage difference between the first reference voltage and the first voltage; second elements each electrically connectable with corresponding first element and for holding second voltage difference between the second reference voltage and second voltage according to the first voltage, and during supply of drive current, controls each first element to hold the first difference by electrically disconnecting the first and second elements, and temporarily suspends supply of the drive current, and controls the second element to hold the second difference by electrically connecting the first and second elements, such that the drive current according to the second voltage difference is supplied.

主权项

1. An optical print head comprising:
a plurality of current-driven light-emitting elements that are disposed in a line shape; an earth line; a first power line that is different from the earth line and supplies a first reference voltage; a second power line that supplies a drive current to each of the light-emitting elements, and supplies a second reference voltage; a first voltage output unit that outputs, with respect to each of the light-emitting elements, a first voltage indicating a light emission amount of the light-emitting element; a plurality of first holding elements that are provided in one-to-one correspondence with the light-emitting elements, and are each for holding therein a first voltage difference between the first reference voltage and the first voltage; a plurality of second holding elements that are provided in one-to-one correspondence with the light-emitting elements, are each electrically connectable with a corresponding one of the first holding elements, and are each for holding therein a second voltage difference between the second reference voltage and a second voltage, the second voltage being according to the first voltage; and a control unit that successively performs a first holding operation and a second holding operation in a main scanning period, wherein the first holding operation is an operation that, during supply of the drive current to each of the light-emitting elements, with respect to each of the light-emitting elements, controls a corresponding one of the first holding elements to hold therein the first voltage difference by electrically disconnecting the corresponding first holding element from a corresponding one of the second holding elements, and the second holding operation is an operation that temporarily suspends supply of the drive current to the light-emitting element, and controls the second holding element to hold therein the second voltage difference by electrically connecting the first holding element with the second holding element, such that the drive current according to the second voltage difference is supplied to the light-emitting element after supply of the drive current is resumed.