DETECTING DEVICE FOR SUBSTRATE HOLE POSITION

摘要

PURPOSE:To obtain fixed detection accuracy regardless of the sizes of substrate holes by a method wherein A/D conversion is applied to four analog voltages fed from a four-sectional light sensitive element receiving light projected through substrate holes and arithmetic processing is done by a CPU. CONSTITUTION:Light from a light projector 1 passes through substrate holes 2 and aims at a four-sectional light sensitive element 4. The element 4 supplies lines 5a-5d with detector output voltages which are proportional to the amount of received light at each part of the element 4. The voltages are fed into a multiplexer 7 through buffer amplifiers 6a-6d. The detector output voltages V1-V4 supplied to the multiplexer 7 are converted into a digital signal 12 by a sampling hold circuit 9 and an A/D converter 11 and arithmetic processing is done by a CPU13. A driver 22 is controlled based on the arithmetic result.