Retractable pen with internal tip seating

Abstract

A retractable pen includes a slide cylinder (1) axially coupled to a push tube (17) and slidably but non-rotatably disposed in a surrounding body cylinder (25) and biased toward a retracted position therein by an internal spring (24). The front end of the slide cylinder defines an axially offset open hole (3) and an internal blind hole (3'), and a refill cartridge (8) having an axially offset writing tip (9) and a support tube 11 axially coupled to the cartridge are disposed within the slide cylinder/push tube unit and rotatably but non-slidably coupled to the body cylinder. A grooved cam wall (5) and axially spaced cam ring (16) on the inner surface of the slide cylinder cooperate with cam followers (13) on the outer surface of the support tube, whereby the depression and release of the push tube sequentially effects the extension of the slide cylinder, the 180.degree. rotation of the cartridge and tip, and the retraction of the slide cylinder, to thus transfer the tip between a writing position whereat it extends through the slide cylinder open hole and a retracted position whereat it is protectively seated in the internal blind hole. The cam wall is configured as two elongated slots spaced 180.degree. apart and joined by convex oblique edges, the cam ring edge defines a zig-zag surface matched to but spaced from and slightly rotationally offset from the cam wall oblique edges, and the cam followers are trapezoidal in shape.