| 摘要 |
PROBLEM TO BE SOLVED: To specify defective concave and convex on the surface of a tire and, at the same time, to recognize the sizes of the concave and convex sections and judge the extents of the defects. SOLUTION: The direction, in which a light emitting section emits light toward a tire is different from the direction in which a light receiving section receives reflected light from the tire by an angleθ. Depending upon the raggedness variation of the surface of the tire, therefore, the heightΔh of the tire from a reference plane varies and an offset amountΔd is produced in the radial direction of the tire between reflecting points (an actual reflecting point R on the surface of the tire and a virtual reflecting point V on a reference plane B). As a result,Δh=Δd/tanθholds. Since the offset amount corresponds to the difference of the light receiving position of the light receiving section, the height variation h can be found easily by calculation from the above-mentioned equation when the proper light receiving position of the light receiving section is known.
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