| 摘要 |
PURPOSE:To restrain output current variance resulting from wiring resistors of power source lines and to improve the printing quality of an LED printer by providing the independent power source line for each built-in output transistor. CONSTITUTION:A signal H or L corresponding to printing data is added to printing data inputs 17 to 20 to control the on/off of analog switches 5 to 8. When the printing data inputs 17 to 20 are H, the analog switches 5 to 8 are turned off, and gates for a reference bias voltage VBIAS 22 and output transistors 1 to 4 are blocked to turn on output transistors 1 to 4. Whereas the printing data inputs 17 to 20 are L, the analog switches 5 to 8 are turned on. Consequently, the reference bias voltage VBIAS 22 is applied to the gates corresponding to output transistors 1 to 4 to turn on the output transistors 1 to 4, and a current flows into LEDs 13 to 16. Since the wiring resistors 9 to 12 of power source lines are designed to be equal, any voltage drop in the area comes to the same value V. Moreover, a wiring resistor 23 is so designed that its voltage drop also comes approximately to zero. |
