GB849460A - Improvements in and relating to writing instruments - Google Patents

Abstract

849,460. Writing instruments. JOHNSON, MATTHEY & CO. Ltd. Nov. 21, 1958 [Nov. 26, 1957], No. 36845/57. Class 146(3). In a writing instrument in which a writing unit carrier is projected and retracted by rotation of an operating member rotatably but axially immovably mounted in a body portion in which the carrier is slidable, the operating member and the carrier are formed with cooperating parts consisting of a pin or projection and a cam track comprising a pair of helical cam surfaces extending from a common apex and against which cam track the pin or projection is constantly resiliently urged, whereby rotation of the operating member in either direction of rotation will cause projection and/or retraction of the writing unit. As shewn a ball-point pen comprises a writing unit 1 mounted in a tubular carrier 3 by means of a flange la at the rear end thereof which is held in engagement with a shoulder 3a in the carrier 3 by means of a threaded plug 3b. The carrier 3 is slidable and relatively rotatable in a tubular operating member 4 haing a reduced diameter portion 5 which terminates in a bevelled face 8. The face 8 constitutes two helical cam surfaces 9, 10 which meet at their upper ends (as seen in Fig. 1) in a notch 22. A rotatable collar 6 is mounted on the part 5 of the member 4 and secured against axial displacement by a bush 7. A tubular body member 12 is frictionally fitted at one end over the collar 6 and has a slot 17 which accommodates a laterally projecting pin 11 on the carrier 3. A compression spring 19 is mounted in the body member 12 surrounding the writing unit and is disposed between a shoulder 21 in the body and a flange 20 on the forward end of the carrier 3 so as to urge the pin 11 on the carrier in to engagement with the face 8 of the operating member 4. A sleeve 15 is fitted in the front end of the body member 12 and is internally threaded to engage a barrel tip 25. A barrel portion 23 of plastic encloses the middle part of the pen and a metal cap 24, rotatable relatively thereto, is frictionally engaged over the operating member 4. When the writing tip is projected, as in Fig. 1, the pin 11 on the carrier 3 is engaged in the notch 22. When the cap 24 and operating member 4 are rotated in either direction the pin 11 is forced out of the notch 22 and rides down the cam face 9 or 10 to the lower end thereof under the influence of the spring 19, the writing tip being thereby retracted. Further rotation of the cap 24 in either the same or the opposite direction restores the pin 11 to the notch 22 and forces the writing unit 1 forward to projected position against the rearward bias of the spring 19. The invention is also applicable to mechanical pencils, in which case the ball-point writing unit 1 is replaced by a lead carrier formed integrally with the carrier 3.