| 摘要 |
PURPOSE:To detect an operator with a good accuracy in a cost-saving and simple constitution by providing means for detecting the floor surface at all times and means for determining the presence of an operator. CONSTITUTION:The detecting surface of a pyroelectric infrared sensor 101a is arranged downward. While a value when the sensor 101 detects the floor surface is set as an OFF value representing that an operator is absent, an operator detecting area is set between the sensor 101a and the floor surface. An ON/OFF detecting part 101b detects and judges the presence/absence of an operator within the detecting area based on the change of the detection value of the sensor 101a. In this case, if the detectable distance M>L/cosalpha of the sensor 101a is preliminarily set, taking the variation of components and the deterioration with time into consideration, the accuracy of the sensor itself is not required and a low-cost sensor is employable. Moreover, the detection distance L is not dependent on the characteristic of the sensor, eventually improving the detecting accuracy. The OFF value is updated at a predetermined interval, so that the accuracy is furthermore improved. |
