A power switch circuit includes first and second power switches, first to fourth inverters, first and second diodes. The belt support member has a cylindrical shape partly cut out along an axis line direction and is capable of changing the size of the cross section area. A container resides on the server and handles requests made for the result of a dynamic page. Further, the color of light can be spatially divided, and still further, it can also be temporally divided by changing the wavelength due to a voltage.