Patent ID: 8463129
Filing Date: 2013-06-11
Classification: H04B

Abstract:
1. A light transmission module comprising: an optical converter for converting an electrical signal to an optical signal; a light transmission path for transmitting the optical signal converted by the optical converter; an electrical transmission path for transmitting an input electrical signal; a control instructing unit for instructing stop of drive to the optical converter based on a detection of an input electrical signal, an input transmission path for transmitting an input electrical signal; an electrical transmission path for transmitting an electrical signal other than a predetermined frequency; a branched portion for branching the electrical signal transmitted through the input transmission path to a path directed to the light transmission path and a path directed to the electrical transmission path; a frequency selecting portion for passing the electrical signal other than the predetermined frequency; an output transmission path for outputting a signal transmitted through the light transmission path or a signal transmitted through the electrical transmission path; and a coupling portion for coupling the light transmission path and the electrical transmission path to the output transmission path, wherein, when an input electrical signal having a predetermined frequency is detected, the input electrical signal having the predetermined frequency is converted to an optical signal and transmitted in the light transmission path, wherein, when input of an electrical signal other than the predetermined frequency is detected, the electrical signal other than the predetermined frequency is transmitted by the electrical transmission path without being converted to an optical signal due to the stop of the drive of the optical converter, wherein an amplitude of an electrical signal that becomes the predetermined frequency is an amplitude smaller than a reference amplitude set in advance; wherein the control instructing unit determines whether or not the amplitude of the input electrical signal is smaller than the reference amplitude and instructs the stop of the drive to the optical converter assuming the input of the electrical signal other than the predetermined frequency is detected when the amplitude of the electrical signal is greater than or equal to the reference amplitude; wherein the frequency selecting portion is arranged to be closer to the branched portion side than the control instructing unit on the electrical transmission path; wherein the control instructing unit determines presence of an electrical signal input from the frequency selecting portion, and instructs the stop of the drive to the optical converter assuming the input of the electrical signal other than the predetermined frequency is detected when determined that the input of the electrical signal is present; and wherein the electrical transmission path includes a first high input impedance circuit at a connecting portion with the branched portion and closer to the branched portion side than the frequency selecting portion so that the light transmission path is segmentalized from the electrical transmission path by high impedance.