PURPOSE: To detect an image formation position with precision more than the resolution of an element, by moving a body to be measured until the logical level of a binary-coded signal is inverted, and measuring the moved distance with resolution more than the detection resolution of the element.
CONSTITUTION: The output signal (video signal) of a photodiode linear array 1 is coded by a binary coding circuit 27 into a binary signal and the binary- coded signal of the display of a specific element is read by a signal reading circuit 28 and stored in a storage circuit 29. A driving circuit 30 indicates the moved direction and extent of a driving table 26, which is moved through a pulse motor driver 31. The signal reading circuit 28 reads the binary-coded signal of the specific element display again after specific-extent driving (e.g. 0.5μm). A binary-coded signal read by a CPU32 previously and the binary-coded signal read after the driving are compared with each other to decide on a position where the logical level of the binary-coded signal is inverted. Simultaneously, the movement extent required for the inversion is counted to calculate an error value to find a real position. This method improves the detection resolution which is limited by element pitch.
INOUE ISAMU
YONEZAWA TAKETOSHI
KOSUGI MAKOTO
| JPS53109658A | 1978-09-25 |
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