| 摘要 |
PROBLEM TO BE SOLVED: To provide a hole detecting device capable of detecting a through-hole with accuracy even when using printing paper of different transmissivity and when parts deterioration has been caused with time or the like. SOLUTION: A printer part control circuit 94 calculates a threshold for determining detection of a through-hole arranged in the printing paper based on a received light quantity when the printing paper is present at a detecting position of a photodiode 170, and outputs it to a comparator 164 via a D/A converter 156. The comparator 164 compares this threshold with voltage according to a received light quantity of the photodiode 170, and outputs the comparison result to the printer part control circuit 94 as a hole detection signal. The printer part control circuit 94 calculates a threshold for each kind of printing paper and outputs it to the comparator 164 via the D/A converter 156.
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