| 摘要 |
PURPOSE:To make it possible to obtain a main scanning signal of desired line thickness by using a plate of rough slit array thickness, by multiplying and leading out a signal obtained from the detector of a main scanning signal generating circuit using a PLL circuit. CONSTITUTION:Phase detector PD receives and shapes scanned analog signal S1 into rectangular-wave signal S2 and also makes a phase comparison to signal S3 outputted from frequency-dividing circuit D2 to generate a signal that corresponds to the difference. Then, LPF-F receives this difference signal to remove its high frequency component and sends its output to VCO to equalize its frequency and phase difference to those of signal S1. Then, the output of VCO varies synchronizing with signal S1. The free-running frequency of this VCO is set four times that of signal S1 by timing circuit T and VCO output signal S4 is inputted to half-frequency-dividing circuits D1 and D2. Therefore, signal S3 of the same frequency with signal S1 is outputted from circuit D2 to detector PD and from circuit D1, accurate eight/mm. line thickness main-scan signal S5 of the double frequency can be led out. |
