Weft yarn detection device of weaving machine

The invention relates to a weft yarn detection device of a weaving machine, which is used to prevent detection delay of weft yarns. During weft insertion of weft yarns of a light absorption system, a light receiving signal (Y2) is output. Because the light receiving signal is used to absorb light by black yarns, a signal level is lower than a light receiving signal (R) of a deformation reed. The light receiving signal is removed by a low frequency removing filtering circuit, and is used to form a high frequency signal (F). In the high frequency signal, an initial light receiving signal (LF) is generated on a negative side. After the high frequency signal is amplified, the high frequency signal is input in a full wave rectification circuit, and a full wave rectification signal (FR) is removed. In the full wave rectification circuit, the negative signal of the high frequency signal, namely the initial light receiving signal, is used as the positive signal, and then is converted into an initial full wave rectifi