| 摘要 |
PURPOSE:To automatize the operation of the titled device by knowing the placing of a finger with total reflecting light from a fingerprint on a bent glass and outputting a mechanical driving signal when the area of the peak part of the fingerprint is more than a prescribed one. CONSTITUTION:When the finger is placed on a bent glass body, a value lower than that of a binarization slice level is obtained at the peak part of the fingerprint, and the rate increases in accordance with the increase of the quantity of perspiration. Consequently, by observing the output of a comparator 6, it can be known whether or not the finger is placed. A counting circuit 8 counts the number of signals 1 outputted from the comparator 6 during number of 32 times of main scannings. That is, the area of the crest part of the fingerprint is obtained. A comparator 9, when the output of a counting circuit 7 is larger than the value set at a constant setting circuit 10, namely when the crest part of the fingerprint goes to be more than the area set at the constant setting circuit 10, outputs a mechanical driving starting signal. |
