| 摘要 |
<p>A reproduction apparatus for producing copies of a document selectively at one of a plurality of copy image magnification ratios. The apparatus includes a microprocessor for control of the optical components for variable magnification, the control including a bidirectional AC motor (41) a reference potentiometer (42), an analog to digital (A/D) converter (98), and triacs (94, 96) for driving the motor. The potentiometer voltage represents the present position of the optical components in the reproduction machine. The position of the optical components determines the actual magnification ratio of images. Upon selection of a particular magnification ratio, a digital position word from memory (99) corresponding to the selected magnification ratio is compared (102) to the optical component current position voltage converted through the A/D converter (98). Depending upon the error signal generated by the compare operation, a run bit is set to activate the motor in the direction to minimize the error signal and position the optical components to achieve the magnification ratio selected. As the optical components near the desired locations, the motor is selectively pulsed to progressively decrease the duty cycle of operation. For example, the duty cycle of operation is decreased from 100 percent to 70 percent, 50 percent, and 30 percent to slowly position the optical components and minimize inertia effects.</p> |
