| 摘要 |
PURPOSE: To provide an LED printing head driving circuit, by which the output voltage developed from a control voltage generating circuit can be accurately controlled and, at the same time, the rate of change of the increment of output current can be smoothed over the whole range of the output current. CONSTITUTION: A switching means 16 selects a reference voltage value within the range of the reference voltage VDD generated by a reference voltage generating source 17 so as to supply the selected reference voltage to a digital-to-analog converter 15. In the digital-to-analog converter 15, on the basis of the supplied reference voltage value, the reference voltage having the range V--V+ narrower than the range of the reference voltage is set. The digital-to-analog converter 15 sets increments in the narrow ranged reference voltage V--V+ so as to generate gate voltage VG in correspondence to the increment. The gate voltage VG controls a transistor TR in order to control the quantity of light emitted from an LED 10. |
