Patent ID: 7273174

Claim:
An optical pen having a light path coaxial with its pen tip, comprising: a shaft extending a predetermined length; a pen tip arranged at one end of shaft and having a defined axial direction; a light source for producing light to shine on the vicinity of pen tip; and an optical sensor for receiving imaging light from the vicinity of pen tip and converting it into an electrical signal; wherein the path traveled by the imaging light overlaps with said axial direction; wherein said optical pen further comprises: a control unit connected to the light source and the optical sensor to receive the electrical signal from optical sensor and generate a first corresponding control signal after processing; a button connected to the control unit which, when pressed, enables the control unit to generate a second corresponding control sign; an elastic member connected to the pen tip and enabling the pen tip to extend and retract a predetermined distance upon an exertion of an external pressure; and a pressure sensor disposed inside the shaft adjacent to the pen tip, detecting an extension and retraction of the pen tip, and generating a third corresponding control signal; wherein both said light source and said optical sensor are connected to the pen tip, when the pen tip is extended and retracted, the light source and the optical sensor move with the pen tip.