| 摘要 |
PURPOSE:To attain high quality of an output picture by constitution that the center value of a dot controlled in response to the output value of a picture signal comes always to a prescribed position. CONSTITUTION:A 2-bit digital signal inputted from terminals 2a, 3a is converted into a 4-bit decoding signal at a decoder 6 and its high-order 3-bit is latched at a latch circuit 8 by a transfer clock CLK in a period T. A clock CLKH having a frequency three times that of the CLK is inputted to a pulse width modulating circuit 7, where the clock is converted into three clocks CLKH1-CLKH3 different in duty. Latch circuis 12, 13 generate a pulse CLKH1' having the period T, delayed by 1/3T and 1/3T of duty and a pulse CLKH2' having a period T delayed by 1/6T and 2/3T of duty from the CLKH1 and CLKH2. The CLKH1', 2' and 3 drive a transistor 11 via an AND gate 9 and an OR gate 10 together with an output of the circuit 8 to light a laser diode 1a, thereby making the center position of each dot in response to the 2-bit signal coincident with each other.
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