Patent GB-898555-A (GB)
Title: Latch mechanism assembly for retractable ball-point pen
IPC: B43K24/08
Filed: 1958-09-22
Abstract: 898,555. Reservoir pens. SCRIPTO Inc. Sept. 22, 1958 [June 3, 1958], No. 30185/58. Class 146(3) A retractable ball-pen includes a latch member rockable and slidable in the barrel for locking the writing unit in projected and retracted positions, and a plunger slidable in the rear end of the barrel and having forwardly facing surfaces which engage the latch member and rock it upon depression of the plunger, a leg portion on the plunger extending forwards beyond the contact surfaces thereon and adjacent to a side face of the latch member to which it is attached by a lug and groove connection. As shown in Figs. 3, 6 the pen has a barrel formed in two parts 12, 14, and a writing unit 16 slidable therein and rearwardly biased by a spring in the front barrel part 12. An assembly sleeve 36 is mounted in the rear barrel part 14, being retained therein by ridges 36<SP>1</SP> which frictionally engage the inner wall of the barrel and by a cup-shaped member 42 also frictionally fitted into the barrel. The assembly sleeve 36 is generally cylindrical but has a flat face 52 over part of its length and at its lower end has diametrically opposed slots 44, 46 of different lengths terminating in longitudinally spaced shoulders 48, 50. The plunger has a cylindrical end portion 70 of greater diameter than the internal diameter of the assembly sleeve 36, and a reduced portion 72 which is slidable within the sleeve 36. At the front end of the plunger portion 72 are formed inclined faces 74, 76, and projecting beyond these faces is a leg 78. The latch member 38 has inclined faces 54, 56 at its rear end to co-operate with the faces 74, 76. The latch member is slidable within the assembly sleeve 36 and abuts against the flat face 52 thereof with one of its broad sides; the other broad side of the latch member has a groove 68 in which a lug 80 on the plunger leg portion 78 engages loosely. The front end of the latch member abuts against the rear end of the writing unit and has laterally extending arms 62, 64. In projected position of the writing unit, Fig. 6 the arm 62 is engaged under the shoulder 48 of the assembly sleeve and the rearward pressure of the writing unit 16 on the forward end of the latch member causes the latter to tilt in a clockwise direction until a fulcrum point 60 thereon engages the inner wall of the assembly sleeve. In this position face 76 on the plunger engages face 56 on the latch member; pressure on the plunger causes the latch member to rock in a clockwise direction about the fulcrum point 60 thus disengaging the arm 62 from the shoulder 48. When pressure on the plunger is released the writing unit is retracted by its spring and carries the latch member backwards until the arm 64 thereon engages under the shoulder 50 and the unit is thereby latched in its retracted position. In this position a fulcrum point 58 on the latch member engages the inner wall of the assembly sleeve and the face 74 of the plunger engages the face 54 of the latch member. A second depression of the plunger returns the parts to the Fig. 6 position. The parts are so dimensioned that the lug 80 on the plunger leg at no time touches either the upper or the lower edge of the groove 68 so long as a writing unit is mounted in the barrel; the purpose of the connection is to retain the plunger, assembly sleeve and latch member in an assembled relationship when the pen is dismantled. The sleeve 36 may be formed integrally with the barrel and the slots 44 46 may be of the same length, the arms 62, 64 on the latch member being longitudinally spaced in this case. In a modification, Fig. 8, an opening 82 is formed in the rear barrel part 14<SP>1</SP> adjacent to the shoulder 48 on the assembly sleeve. A release member 84 is mounted in the pocket clip 86 and has a finger portion 88 extending into the opening 82 so that it engages the arm 62 of the latch member 38 when the arm is engaged under the shoulder 48 in projected position. Inward manual pressure on the member 84 disengages the arm 62 from the shoulder 48 and allows retraction of the parts. In a further modification, Fig. 10, the rear barrel part 14 is apertured at 92 and a release member 94 mounted in the pocket clip 96 has a finger portion 98 extending therethrough for engagement, when the member 94 is pressed inwards, with a cam face 90 provided on the plunger reduced portion 72. The action of the finger portion 98 on the cam face 90 causes the plunger to move forward and actuate the latch member. Reference has been directed by the Comptroller to Specification 804,903.