| 摘要 |
PURPOSE:To reduce acceleration in the returning and positioning of a light source for lighting an original and reduce oscillations by varying the set value of a motor current gradually with time from the reversing or braking start point of a motor. CONSTITUTION:A set analog signal KA rises to a permissible limit value at a scan start time point. At this time, a rotation direction control signal DR is in a normal direction. A motor current increases abruptly and the light source for lighting the original increases up to a specified speed according to acceleration corresponding to a permissible maximum current value, and a run in the normal direction is carried out at the specified speed under constant-speed control of the loop of an encoder 16, phase comparator 18, LPF 19, pulse width modulator 20, transistor (TR) 11, and motor 17; and the rotation direction control signal DR is inverted at a run completion point of specific distance. A control system is switched to the constant current control by a CPU 30, DA converter 32, current detecting resistance 15, differential amplifier 24, and TR 11, and the set analog signal KA increases stepwise at a specific rate. Thus, the light source for original lighting is accelerated with specific acceleration. |
