| 摘要 |
<p>An optical irradiation section (2) irradiates an end face of a light-guide sheet (6) with light. A photodetection section (3) receives the light transmitted through the light-guide sheet (6) and detects an X value and a luminance value. A first evaluation section (421) of an evaluation section (42) evaluates whether or not a Y1 value corresponding to the X value detected by the photodetection section (3) exceeds a prescribed threshold value, based on a correlation (a) stored in a first storage section (411). A second evaluation section (422)evaluates whether or not the total light transmittance corresponding to the luminance valuedetected by the photodetection section (3) is less than a prescribed threshold value, based on a correlation (ß) stored in a second storage section (412). If it is evaluated that the Y1 value exceeds the prescribed threshold value, an output section (43) outputs a signal indicating that yellow is present to an excessive degree. If it is evaluated that the total light transmittance is less than the prescribed threshold value, the output section (43) outputs a signal indicating a drop in transparency.</p> |
