| 摘要 |
PURPOSE:To ensure a highly efficient positioning of an image sensor, by inverting the image of the bright/dark identifying mark provided in a body with the image sensor against the optical axis to project the image onto the image sensor and detecting the variation of output according to the degree of deviation to the optical axis to give a minute shift to the identifying mark. CONSTITUTION:The reflecting plates 8a and 8b are provided right before the image sensor 4 in such way that the edges of the reflecting plates become parallel to the array direction of the sensor's light receiving parts. These reflecting plates are irradiated by the lamps 9a and 9b, and the reflected light enters the image forming lens 3. The plates 8a and 8b become bright; while a dark part is formed at the slit-shaped region having a longer direction vertical to the paper surface and formed by the gap between the reflecting plates. Now if the sensor 4 is at the normal position in terms of the (v) direction, a coincidence of the image is obtained between the plates 8a and 8b. Thus the regular incident light volume does not exist at the light receiving part of the sensor 4, and only the bias component is delivered there. As a result, a highly efficient positioning is possible for the image sensor by fixing the sensor at the position where the output becomes minimum. |
