LASER DIODE CONTROLLER

PURPOSE:To give high synchronous precision for actualizing multi-gradation by a miniaturized device at low cost. CONSTITUTION:The synchronous precision with a reference picture element clock (CLOCK) is enhanced for actualizing the multi-gradation by using a voltage control oscillator(VCO) 2 comprising a phase lock loop for high-frequency oscillation without frequency-dividing said (CLOCK) to be externally inputted. Next, the laser diode light emission starting time setting up signal (W-CLK) is set up by the synchronous position signal with the signal transmitted from the output of VCO 2 by a tap selecting circuit 5 to decide the shift numbers of a barrel shifter (B.S) 6 using the initial output after the shifting step. Furthermore, the output of VCO 2 synchronously detected by the barrel shifter 6 is gradated by T/2N using a PWM pulse formation logic circuit 7 to form PWM wave forms so that the output may be compared with written-in data (W-DATA) to output the PWM wave forms by a synchronous pulse selecting circuit (S.P.S) 9.