| 摘要 |
The present invention realizes excellent controllability of print position even when a print head is driven at accelerating or decelerating speed while keeping advantages of fine and high resolution printing quality. A position information signal generator 9 in an ink-jet plotter comprises an interpolating circuit 12 which generates a first position information signal based on an A-phase output of A-phase and B-phase outputs from a sensor 5, an edge detector 13 which generates a second position information signal by multiplying the A-phase and B-phase outputs by four, a selector which selects the outputs from the interpolating circuit 12 and the edge detector 13, and a select control circuit 15 which switches the selector 14. The interpolating circuit 12 takes only the A-phase output of the A-phase and B-phase outputs to detect the edges in the A-phase output, and divide intervals between the detected edges based on resolution indicated by a resolution indicating terminal 11, then interpolates pulses corresponding to the indicated resolution into the pulse intervals to obtain the first position information signal. The edge detector 13 detects rising edges and falling edges in the A-phase and B-phase outputs, and synthesizes the detected edges to obtain the second position information signal. The select control circuit 15 detects the head speed or acceleration of a print head 2 based on information from the interpolating circuit 12, and controls the selector 14 based on the detection result.
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