Pen digitisor and transmitter housing

摘要

A transmitter device 40 for an electronic whiteboard houses a conventional pen 42 and includes transmitters 58, 60 surrounding the pen adjacent the pen tip. The annular wedge surface 48 centers the pen within the bore 50 and the pen is biased against the wedge by the centering cap 60 biased against the other end of the pen by the spring 56. When the pen tip is contacted against the writing board, the relief of pressure applied by the pen against the wedge surface 48 is sensed by a microswitch to actuate the transmitters.