| 摘要 |
PROBLEM TO BE SOLVED: To provide an evaluation method for reflection sheet capable of a non-destructive measurement, using the device apart from a mark, and exactly and easily obtaining data comparable to a reference value in not using. SOLUTION: Light (V1) from a light source 1 is cast on the reflection surface 92 of a reflection sheet 91 with a specific brightness and a specific incidence angle. Brightness of reflection light (V2) formed by the reflection of the light (V1) from the light source 1 at the reflection surface 92 is measured. On the other hand, the distance (D1) between the reflection surface 92 and the light source 1 is measured and by using the distance (D1), the illuminance of light having reached the reflection surface 92 is obtained. The actually measured brightness or the reflection performance obtained using the brightness is converted to a corrected value so that it is measured in standard conditions including the standard source illuminance. The brightness of an unused reflection sheet measured in the standard conditions or reflection performance is made a reference value. By comparing the reference value and the corrected value, the brightness of the reflection sheet 9 in use or the variation degree of the reflection performance is evaluated.
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