| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a switching apparatus capable of freely setting a time during the detection of the interception of incoming light and the switching of the light by providing a switching protection time circuit. <P>SOLUTION: An optical line switching apparatus, which outputs an optical line switching signal for switching one line to the other line of a duplex line when an incoming light level constantly detected by a level detecting means 3b becomes not more than a predetermined value 3a, comprises a protection time setting means 3c capable of setting an arbitrary protection time and a switching control means 3d for outputting the optical line switching signal after the incoming light level becomes not more than the predetermined value 3a, only when the incoming light level continues during the protection time. <P>COPYRIGHT: (C)2003,JPO |
