Patent ID: 7633075
Filing Date: 2009-12-15
Classification: G04C

Abstract:
1. A through hole formation state determining device comprising a light emission element which emits light when electrically driven, at least one moving member with an aperture through which light can pass, and a photodetection element which detects light from the light emission element, thereby outputting a detected signal indicative of the intensity of the detected light, the light emission element and the photodetection element being disposed at such positions that when the aperture in the at least one moving member aligns with a predetermined position, light from the light emission element passing through the aperture to the photodetection element, the through hole formation state determining device being further comprising: external light intensity setting means for capturing a detected signal from the photodetection element when the light emission element is in a non-emission state and for setting the measurement of the detected signal as the intensity of the external light; and determining means for capturing a detected signal from the photodetection element when the light emission element is in a light emission state after the intensity of the external light is set by the external light intensity setting means, for offsetting a threshold to be compared with the detected signal by the intensity of the external light, for comparing the offset threshold with the value of the detected signal, and for determining in accordance with a result of the comparison whether the aperture in the at least one moving member is at the predetermined position.