US Patent 7469619 Electronic torque wrench with a torque compensation device

An electronic torque wrench for driving a workpiece includes a wrench body having a handle end and a wrench head receiving end. A wrench head a workpiece receiving end and a mounting end, and the mounting end is removably received by wrench head receiving end. A user interface having a processor and a display is mounted on the wrench body. A wrench head sensing device is carried by the wrench head receiving end and includes an electrical connection between the wrench head sensing device and the processor. The wrench head sensing device sends an electrical signal to the processor indicating the presence of the wrench head on the wrench head receiving end.