| 摘要 |
PURPOSE:To prevent the noise produced by the regular reflection of a fine grain by illuminating a object right from above, giving photoelectric transducing and amplification to the same area to detect reflected light at two areas of an upper oblique side and synthesizing two signals after shading correction and a binary coding. CONSTITUTION:A sheet containing a pattern 3 is put on a table 14 and shifted horizontally by a motor 13 and via a ball screw 28. Then the sheet is irradiated right from above by an optical system consisting of a light source 15, a condenser lens, a half mirror 17 and a filter 18. The point of irradiation forms images to two sensors 20a and 20b through image forming lenses 19a and 19b having the same magnification ratio and set at the upper oblique side. Both sensors 20a and 20b and a motor driving circuit 27 are controlled synchronously with each other by a sensor driving circuit 21. The outputs of sensors 20a and 20b are amplified 22a and 22b, and the shading is corrected 23a and 23b for the correction of variance of both illumination and sensitivity and for the binary coding 24a and 24b. The outputs of both binary coding circuits are fed to an AND circuit 25 to produce an output signal. Thus it is possible to erase the regular reflection of metallic fine grain by the difference of timing. In such a way, the noise level can be lowered. |
