Design of an advanced computer writing tool

This paper describes the development of an advanced computer writing tool, called SmartPen. The SmartPen is a computer pen that enables simultaneous writing on paper and on computer. The position of the pen on the writing surface is calculated through measurements of miniature force and acceleration sensors mounted in the pen body. In first instance, the measurements serve as input for a graphic data file. Further processing can lead to a standard text format. As the SmartPen has also a push-button, mouse and joystick functions can be emulated. This paper will concentrate on the development of the force and acceleration sensors together with the overall pen body design. The forces or accelerations during writing are measured with a miniaturised force and acceleration sensor based on strain gauge technology. The design is optimised for mass production and also includes a mechanical protection against shock loading (e.g. when the pen falls from your desk). The pen body is designed as a highly integrated electro-mechanical connector providing a mechanical ground for all force measurements and the necessary electrical connections. Moulded interconnect device technology is used to realise these functions in one single element, thus eliminating nearly all wiring.