| 摘要 |
PURPOSE:To make a shared use of an original oscillator for ILL and other clock generating circuit and to simplify the circuit by setting the linear velocity L so that L=(1/M)XN with the dot density per unit length being M dot. CONSTITUTION:The diagram shows the relation between the dot density M and the linear velocity L. The circle marks indicate dots and the beam scanning is performed horizontally. With the dot density equal to M, the interval DELTAd between adjoining dots is expressed as 1/M. The linear velocity L is set so as to be integer times the dot interval 1/M. That is, with the integer N, the linear velocity L is set so as to be L=(1/M)XN. With the integer set in this manner, the horizontal scanning frequency is always integer. With the horizontal scanning frequency being integer, the frequency of the clock impressed to the motor for rotating a polygonal mirror may be integer so that the original oscillator for the PLL circuit may be used in common with original oscillators used for frequency division of CPU clocks.
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