| 摘要 |
PURPOSE: To play tennis always in a satisfactory condition, by arranging a plurality of light fittings restraining light incident upon a wall surface in accordance with an arrangement, and having inherent oblique light angles, above a court. CONSTITUTION: Each light fitting is arranged so that it does not emit light at an angle greater than a vertical angleθindicated by the formulae in dependence upon a horizontal angleϕ, where H is an attaching height of a light fitting, W1 is a distance between a light fitting and one of side walls, W2 is a distance between a light fitting and the other one of side wall, D1 is a distance between a light fitting and one of walls in rear of base lines, D2 is a distance between a light fitting and the other one of walls in rear of base lines, a vertical angleθ=0 deg. is a vertically downward direction of each light fitting,ϕis a horizontal angle clockwise around the axis of the above vertical angleθ=0 deg., and a horizontal angleϕ=0 deg. is a side wall direction from a light fitting to the distance W1 . With this arrangement, light radiated from each light fitting is incident upon a ball and a court surface, but is not incident directly upon the wall surfaces around the court. Thus, the relationship between the light intensity LB of a ball and the light intensity LW of the wall surface as a background is always held as LB>LW.
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