GB849949A - Improvements in and relating to retractable ball-point pens - Google Patents

Abstract

849,949. Reservoir pens. KREUTZER, R., and WEISMULLER, G., [trading : as STAEDTLER, J. S. [Firm of]]. April 11, 1958 [July 19, 1957], No. 11618/58. Class 146(3). In a retractable ball-point pen with a plunger-actuated, return spring-loaded writing unit in which the projected and retracted positions of the writing unit are determined by at least one ball, the writing unit and a guide tube therefor perform a slight rotary motion with respect to the barrel at each operation of the plunger and for this purpose the ball rests within a recess in the guide tube, the return spring is located between an abutment on the guide tube and a sleeve inserted in the barrel and the ball co-operates with oppositely directed control recesses and teeth provided in two bushes associated with the sleeve. The rear end of the writing unit o is received in an axially slidable guide tube l, an extension z of which frictionally grips the unit. The barrel of the pen consists of two parts a b fastened together by an externally threaded sleeve c. Slidable in the rear end of the barrel part b is a plunger g to the forward end of which is fastened a pressure sleeve i having an inturned flange m at its front end. The pressure sleeve i is slidable over the enlarged rear end k of the guide tube l, the flange m abutting against a shoulder n thereon. A spring t bears against the flange m to bias the guide tube l and writing unit o towards retracted position. Bushes r, s, having cam faces as shewn in Fig. 4 are fixed to the inner surface of the sleeve c. Three balls q are carried in recesses p in the guide tube l and cannot move either circumferentially or longitudinally in relation to the tube. When the balls q are engaged in the recesses B of the bush s the writing unit is retracted. Pressure on the plunger g first relieves the guide tube l of the rearward bias of the spring t, and then, when the plunger has travelled forwards a distance A, urges the guide tube t and writing unit o forwards until the balls q engage inclined cam faces c on the bush r, which engagement partially rotates the parts l, o. Release of pressure on the plunger allows the parts l, o to be carried back by the spring t until the balls q engage inclined cam surfaces E on the bush s and come to rest in recesses F, the writing unit then being in projected position. A further depression of the plunger restores the unit to retracted position, the unit being rotated slightly relatively to the pen barrel at each actuation of the plunger. In a modification, Fig. 2 (not shown), a helical spring may be interposed between the guide tube l and its gripping extension z so that the writing unit yields resiliently in writing position.