Electronic pen with retractable and replaceable cartridge

摘要

An electronic pen comprises a user-replaceable cartridge having a nib, a force sensor for sensing a nib force transmitted axially through the cartridge from the nib and a retraction mechanism for retracting the cartridge. The retraction mechanism comprises a barrel adapted for seating the cartridge in either an extended position or a retracted position, and a first biasing mechanism for biasing the cartridge towards the extended or retracted positions. A second biasing mechanism biases the barrel towards engagement with the force sensor.