| 摘要 |
<p>PROBLEM TO BE SOLVED: To reduce the influence of skylight illumination causing noise, and enable accurate detection of direct sunlight, by judging direct sunlight on the basis of each detection signal of a light detecting part, when light shielding material does not shield the direct sunlight, or shields it. SOLUTION: A light receiving part 2 is arranged facing upward, at the center of a base 1, which is covered with a semi-spherical transparent cover 3. A semi-circular light shielding part 4 is fixed to the base 1, and 180 deg. reciprocal pivotal movement along the outer or inner surface of the cover 3 around a horizontal shaft 6 is made possible by a driving part 5. For example, the horizontal shaft 6 is arranged in the east and west direction, and the light shielding part 4 is made to pivot in the north and south direction. In this case, a detection signal V of the light receiving part 2, at a position where the light shielding part 4 does not shield sunlight, becomes the sum V1 of the direct sunlight and the skylight from the part except the direction of the sun. At the position where the sunlight is shielded, the detected signal becomes V2 which is an amount of only the skylight. As a result, the level of only the direct sunlight at the position where the sunlight is shield becomes the difference between the sum V1 and the skylight amount V2 . Therefore the influence of skylight illumination causing noise is reduced, and direct sunlight can be accurately detected.</p> |
