| 摘要 |
PROBLEM TO BE SOLVED: To restrain a wetted surface from being affected by a difference in reflectance, and to precisely detect liquid leakage and attaching abnormality. SOLUTION: A prescribed attaching-abnormality detecting threshold value is set in an attaching abnormality comparator 59 to be compared with a photo- reception level from a photo-receiving part 51. The photo-reception level in the photo-receiving part comes below the attaching-abnormality detecting threshold value when this liquid leakage sensor of the present invention is brought normally into the attaching abnormality, and an attaching abnormality signal is output from the comparator 59. On the other hand, an output signal in response to a variation of the photo-reception level per unit time is imparted to a liquid leakage comparator 61 in a differentiating circuit 60, by differentiating a reception signal from the photo-receiving part. When the liquid leakage is generated to make a liquid flow in between the liquid leakage sensor and the wetted surface, the variation of the photo-reception level per the unit time exceeds a liquid leakage detecting threshold value to output a liquid leakage detection signal from the liquid leakage comparator 61. COPYRIGHT: (C)2004,JPO
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