| 摘要 |
PROBLEM TO BE SOLVED: To prevent the crash death of fish to the wall of a water tank, wound and the accumulation of stress without causing the panic of fish, by gradually raising the illumination in the water tank by a light modulating means when controlling lighting. SOLUTION: When controlling lighting, the illumination is raised by a preset rising ratio by a light modulating means to give a lighted state. To be concrete, for example, a standard lighting time tr and a standard turning-off time td are housed in a ROM 26 of a control part 14 attached to a water tank 11, a corrected timeΔtr to the tr and a corrected timeΔtd to the td are housed in a ROM 27 and a time Tr to make the illumination from 0% to 100% when controlling the lighting and a time Td to make the illumination from 100% to 0% when controlling turning off are housed. Then illumination of the circumferential light is detected by a light sensor 17 and the lighting is controlled by the detected output or by the set time tr or tr+Δtr. In the operation, a lighting command is sent from a CPU 25 to a light modulating machine 31 so as to raise the illumination of a fluorescent light 13 from 0 to 100 % for a Tr time.
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