| 摘要 |
PROBLEM TO BE SOLVED: To minimize variation of an output level caused by a change with the elapsed time of a mechanical relay by conducting at least one operation of relay switching operation corresponding to a change of switching of an image signal and relay switching operation not forming a path. SOLUTION: The switching requirement of an input image signal is received from an input selection part 8. After an outputting mechanical relay 6 is controlled in an open state, an input selecting mechanical relay 4A is controlled in an open→close→open state. Input selecting mechanical relays 4B, 4C are also controlled in an open→close→open state. The open→close→open control of a series of input selecting mechanical relays is repeatedly executed by the specified frequencies of at least one. Thereby, the relay does not keep the same state, and the variation of contact resistance caused by the generation of an oxide film for example in a contact part can be prevented. At the same time, screening is conducted, and a contact resistance variation factor such as foreign matters generated in a contact part can be removed.
|
