| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to limit a quantity of current carried in a light emitting thyristor to a given lavel, by adjusting a bias voltage and compensating the quantity of light emitting from a light emitting element in real-time. SOLUTION: When a pulse corresponding to image data is fed from a pulse generation circuit 106 to a base of a transistor 301, a given current at given voltage is fed to a cathode of a light emitting thyristor through a resistor 101 and capacitance 201. The quantity of current carried at the thyristor is changed into a given voltage level through a resistor 102. The holding value is held in a sample holding circuit 107. The holding value is compared with a reference voltage value Vref by a comparator 401, and on the basis of the difference, the output of the comparator 401 is adjusted. In addition, transistors 302 and 303 are driven by the output of the comparator 401 to control a bias voltage (-Vga). |
