Patent ID: 7438251
Filing Date: 2008-10-21
Classification: B65H

Abstract:
1. A web tensioning device which comprises: a base; an angular position sensor; a dancer arm for engaging the web to be tensioned, having a free end portion with a dancer rotatably mounted thereon and a fixed end portion pivotably mounted to the base so as to coact with the angular position sensor and indicate relative angular displacement of the dancer arm as a web in contact with the dancer is maintained in tension; a servo motor operably associated with the dancer arm for pivotally positioning the dancer arm by application of a compensating torque component in response to a control output signal; and a controller for generating the control output signal in response to acceleration of the dancer arm due to changes in web tension as detected by the angular position sensor; the applied compensating torque component being substantially the same as force of the dancer arm acceleration.