US Patent 6882340 Electronic pen

An electronic pen is provided with a casing. A sensor substrate is formed by arranging two comblike conductive patterns on a flexible substrate so that the conductive patterns are interleaved but do not come into contact with each other. The sensor substrate is wound around part of the casing and is thereby fixed. A pressure-sensitive conductive rubber member is arranged to cover the sensor substrate. A protective grip is provided to cover these portions. Accordingly, a sensor which senses finger contact or a pressure applied by a finger is formed. When a finger presses the protective grip, a circuit on a control substrate detects a change in the relationship between the conductive patterns between which continuity is established by the pressure-sensitive conductive rubber member. The detection is transmitted as operation information to a digitizer by exchanging electromagnetic waves with the digitizer.