Positioning device for scanner

A manually operable scanner for movably supporting a sensor adjacent a body to be scanned for detecting characteristics of the body and for providing continuous signals indicative of the location of the sensor to provide an automatic indication of the location of sensed characteristics on the body, said scanner comprising portable frame means positionable adjacent a body to be scanned, carriage support means on said portable frame means supporting a carriage on said portable frame means for manually effected movement in either direction along a first axis, carrier means on said carriage for supporting a sensor carrier frame on said carriage for manually effected movement on said carriage in either a direction along a second axis perpendicular to said first axis, sensor means mounted on said sensor carrier frame, whereby said sensor means can be manually moved in any direction including a component of one or both of the first and second axes, a first encoder, a second encoder, said first and second encoders each providing an output count and having a rotary input shaft and counting up in response to rotation of its rotary input shaft in a first direction and counting down in response to rotation of its rotary input shaft in a reverse direction, a first mechanical drive connection between said carriage means and the rotary input shaft of said first encoder for continuously actuating said first encoder in response to manual movement of said carriage means in either direction along said first axis to continuously provide a first output count indicative of the position of said carriage means along said first axis at any given moment and a second mechanical drive connection between said sensor carrier frame and the rotary input shaft of said second encoder for continuously actuating said second encoder in response to manual movement of said sensor carrier frame in either direction along said second axis to continuously provide a second output count indicative of the position of said sensor carrier frame along said second axis at any given moment and monitoring means responsive to the count of said first and second encoders for providing a continuous indication of the coordinate position of said sensor means with respect to said portable frame means in response to movement of the sensor in any direction including directions canted to the said axes.