Abstract: A digital pen, which comprises an ink cartridge with a writing tip for marking a surface; a camera system for capturing images of the surface in order to digitally record pen strokes formed on the surface, and a detachable cap to be placed at a writing end of the digital pen, is selectively operable as a non-marking pen with the cap placed at the writing end or as a marking pen without the cap placed at the writing end and configured to digitally record pen strokes both when operated as a non-marking pen and as a marking pen.

Abstract: An electronic pen has a body which comprises a casing consisting of at least two casing parts which are joined to be separable, and electronic equipment arranged inside the casing. A girdle is arranged with a close fit round the joined casing parts. The casing and the girdle have coacting locking means which limit the movement of the girdle in the longitudinal direction of the pen in such manner that at least the girdle is destroyed as the locking is broken.

Abstract: An electronic pen comprises a writing means (7) which extends into the interior of the pen, a guiding element (9) for the writing means (7), a sensor (15a) for recording images and an image processor (30) for calculating positions of the pen based on said images. The sensor (15a) is part of an imaging detector unit (15). The guiding element (9) and the detector unit (15) are arranged in a common mounting part (5) which is fixedly mounted in the interior of the pen. In such a pen, it is possible to minimize the tolerance chain between the components that convert a pen stroke on a base into a sequence of positions. This enables serial production of the pen with a small number of rejects.