| 摘要 |
PURPOSE:To simplify a circuit constitution and to improve noise resistance and to reduce a cost, by using a pyroelectric effect element sensing a change of infrared light as a light receiving element. CONSTITUTION:When an infrared light emitting diode 2 switched on and off for projecting modulated light is made scanned in an arrow direction A at the back side of a light projecting lens 4 towards an object to be measured for a distance, the intensity change of the infrared radiation received on a light receiving element 100 at each scanning position in accordance with the distance to the object to be measured varies. As a result, for instance when an infrared light is made incident in the form that the intensity of the infrared light on the element 100 becomes the largest on the way of scanning by the diode 2, an output of the element 100 i.e. a differential output of the infrared light intensity is generated. By using such a pyroelectric effect element sensing a change of infrared light as the element 100, a circuit constitution is simplified and the noise resistance is improved and a cost is reduced. |
