Patent GB-832527-A (GB)
Title: Improved latch means for retractable ball-point pens
Inventor: SMITH BLANCHARD DRAKE
IPC: B43K24/08
Filed: 1956-10-02
Abstract: 832,527. Writing instruments. SCRIPTO Inc. Oct. 2, 1956, No. 30042/56. Class 146(3) A retractable ball-point pen has a rearwardly biased writing unit which is advanced to writing position by inward depression of a plunger slidable in the rear end of the barrel, and a latch nested in the plunger and extending rearwards from its point of abutment with the plunger to engage its rearward part with a latch keeper on the barrel when the plunger is depressed, the plunger then transmitting the load of the biasing means to the latch' in a direction inclined to the longitudinal axis of the barrel to hold the latch against the keeper and transmitting to the barrel the resultant reaction normal to said axis. In one form, Fig. 3, the barrel 11 is threaded at its rear end to receive an assembly sleeve 12, a tubular cap 13 being frictionally held on an unthreaded portion 21 of the sleeve 12. The cap 13 has an aperture in its rear end through which protrudes the rear portion of a plunger 25 which is retained in the cap against the rearward bias of a spring 19 by the abutment of a shoulder 28 formed thereon against an annular flange 22 at the rear of the cap. The plunger 25 is slotted longitudinally at 32 which slot is enlarged to a lateral channel 33 in the forward end of the plunger forming a fulcrum portion 34 therein. The extreme forward portion of the plunger is formed for frictional retention of a ball-point writing unit 14. A latch element 26 is positioned in the slot 32 and a lateral offset 35 thereof extends through the channel 33 for lateral rocking about the fulcrum portion 34. A second lateral offset 36 is formed on the lever 26 for engaging a lateral keeper aperture 37 in the cap 13. The spring 19 also engages a lip 38 on the offset 35 and biases the latch 26 to rock about the fulcrum 34 outwards from the plunger 25. When the writing unit and plunger are in retracted position the latch 26 is held within the plunger 25 by the side wall of the cap 13: on depression of the plunger for projecting the writing point the latch 26 rocks outwardly when the offset 36 comes into alignment with the aperture 37, causing the offset to latch therein and hold the writing point projected. In this position the load of the spring 19 is transmitted to the latch through the abutment of the base of the channel 33 in the plunger with the lower end of the latch. Retraction is effected by pressing the portion 36 inwards out of engagement with the keeper aperture 37, so that the plunger and writing unit are retracted by the spring 19. In another form, Fig. 6, a cap 104 fits directly on to the rear end of the barrel and carries a plunger 108 formed with a shaped slot 110 to receive a latching portion 106 shaped correspondingly. The forward end of the portion 106 is adapted to grip frictionally the rear end of a writing unit 103. Depression of the plunger 108 causes the portion 106 to move outwardly, by reason of the interaction of cam surfaces 111, 113, so that a flange 107 on the cap 104 engages a slot 116 in the portion 106. When pressure on the plunger is released the portion 106 is held latched on flange 107 against the rearward bias of a spring 115 by the cam action of a ridge 112 in the plunger slot 110 on a groove 114 in the portion, and thus the writing point is held in projected position. Retraction is effected by the spring 115 when the slot 116 is disengaged from the flange 107 by pressing the portion 106 laterally inwards. In yet another form, Fig. 10, the latch means consists of a roller 312 positioned in a slot 311 in a plunger 307. Upon depression of the plunger the roller 312 rolls by gravity so that part of its circumference projects through a keeper aperture 305 in a cap 303. An inclined surface 313 under the action of the retracting spring 314 forces the roller 312 into the aperture. The upper edge 306 of the keeper aperture is shaped with an internal boss to assist the latching action. In a modification of this form the roller is biased outwardly by a leaf spring contained in the plunger.