| 摘要 |
PURPOSE:To simplify the structure and to utilize the titled natural illumination device widely in many fields by brinding the operation of the dimming plate of a natural illumination mechanism consisting of a light collecting plate and the dimming plate for adjusting the quantity of light collection of the light collecting plate under the control of a control means and obtaining a desired quantity of light accurately. CONSTITUTION:The light collecting plate 3 and dimming plate 4 of the natural illumination mechanism 2 are both formed of a circular polarizing glass plate. A voltage is set as a desired light quantity value by a variable resistor 8a and the quantity quantity of light collection is detected by a photoelectric converting element 7 in the form of a voltage. Both voltages are compared with each other by an operational amplifier 8b as a light quantity value comparing means and a servo-motor 5 as a driving source is driven with the differential voltage. For example, when the quantity of light obtained by the natural illumination mechanism 2, i.e. the quantity of light passed through the polarizing plate 4 is larger than the set value, the servo-motor is operated by a control means 8 to rotate the dimming plate 4 in such a direction that the quantity of passed light decreases.
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