CONTACT TYPE FINGERPRINT DETECTOR

摘要

PURPOSE:To rationalize a finger placing state by a method wherein a guide for positioning a finger is arranged on a light guide member and light emitting elements are arranged to one of the parts opposed mutually through the finger of the guide while photodetectors are arranged to the other part to detect the finger placing state to the light guide member on the basis of the blocking state of the lights emitted from the light emitting elements to the photodetectors. CONSTITUTION:When a finger 18 is placed on the light guide plate 10 inside a guide 12, the lights emitted from light emitting diodes 14a-14d pass through the finger 28 to invade in the light guide plate 10 at the close contact part of the finger 18 with the light guide plate 10 and a part thereof repeats total reflection to reach the under surface of the other end of the light guide plate 10. The detection signals from the photodetectors 16a-16f are supplied to a microcomputer 24. When the lights from the light emitting diodes 14a-14c are blocked by the finger 18 not to reach the photodetectors 16a-16f, the output of the photodetector concerned is turned OFF. The microcomputer 24 investigates which is turned off among the photodetectors 16a-16f to detect the placing state of the finger 18 to the light guide plate 10 and displays guidance on a display device 26 so as to make the finger placing state proper.