The present disclosure discloses a thread tension adjusting device comprising a body, a tension rod, an elastic element and an adjusting knob. A thread passing eye for inputting a thread is arranged below the body. A tension wheel and a thread passing wheel are rotatably arranged on the body. An adjusting knob is used for adjusting a rotational speed of the tension wheel. The elastic element has one end connected to the body and another end connected to the tension rod. The thread tension adjusting device may ensure stability of tensioning and transmitting of the thread by cooperation between the tension rod and the tension wheel, and improve precision for thread tension adjusting by the adjusting knob. In addition, the thread tension adjusting device may monitor thread breakage by the tension detector, and ensure operating stability and safety of the thread tension adjusting device.

The present invention concerns a device for the transfer of a mechanical force to a piezo-electric element for the generation of an electrical signal corresponding to the mechanical force, e.g. the tension of a thread or the like and/or the movement of the same, wherein the piezo-electric element is positioned in a holder in order to be actuated by the mechanical force on the end surfaces.