| 摘要 |
PURPOSE:To perform pattern detection stably by detecting the upward/downward movement of a body to be detected like a printed board where a pattern is formed by the 1st and the 2nd detectors and then moving up and down the 3rd detector according to the detection output for focus adjustment. CONSTITUTION:The printed wiring pattern 1a is formed on the surface of the printed board 1 as the body to be detected. Light from a light source 6 is passed through a mask 7 provided with black lines 7a-7c and a lens 8 for mask image formation and reflected by a beam splitter 9, and the reflected light projects black line images 2a-2c on the board 1. Reflected light beams from the line images 2a-2c are transmitted through the splitter 9 to form images on photodetectors 5A, 5B, and 5C through a reflected light image forming lens 4. The detector 5C is provided with a moving mechanism 10 which moves up and down the detector on an optical axis 3c. The board 1 is moved as shown by an arrow and the upward/downward movement of the board 1 is detected with the outputs of the detectors 5A and 5B to move the detector 5C with the detection output, thereby making a focus adjustment. Therefore, the detector 5C detects the pattern stably. |
