| 摘要 |
A device for monitoring a thread, for example the weft thread in a loom of the type in which the weft is driven through the shed of the loom with the aid of a jet, such as a gas jet, for example an air jet, and which has a reed with a longitudinal channel for the weft. An arm with a free end is placed in a position at which it is desirable to monitor the weft. The arm free end has at least one light source for illuminating the monitoring point and any weft located there. A number of light-sensitive elements on the arm free end are aimed towards the channel of the reed to sense the light reflected therefrom. Each light sensitive element generates an electric signal corresponding to the reflected light and is connected to an evaluator circuit for adding the signals regardless of whether the weft at the monitoring point results in an increase or a reduction of the signals obtained from the light-sensitive elements, to generate a signal corresponding to the absolute value of the signals. |
