| 摘要 |
<p>PURPOSE:To attain secure detection regardless of the dispersion of light emitting elements and photo detecting elements by increasing the quantity of light that light emitting elements emit after no photo detection output is obtained by 1st scanning on light emitting elements constituting a coordinate surface. CONSTITUTION:With switch 15 ON, one-shot circuit 13 resets X and Y counters 4 and 6 and makes light emitting elements come on for their sequential scans. When no photo detection output is obtained even by indicating light emitting elements on coordinates by indication pen 14 equipped with a photo detecting element, a counter for scanning outputs an overflow signal without stopping to count up. The overflow signal set flip-flop 5 and driving circuit 2 for light emitting elements is so controlled so that the quantity of emitted light will increase. Until detection becomes possible, the quantity of light is increased gradually.</p> |
