Patent GB-900299-A (GB)
Title: Projection-retraction mechanism for writing instruments
IPC: B43K24/02
Filed: 1959-05-14
Abstract: 900,299. Reservoir pens. JOHMANN, F. T. May 14, 1959 [May 29, 1958], No. 16581/59. Class 146 (3). A retractable ballpoint pen comprises a writing unit which is spring urged towards a projected position, a latch element and a latch actuating element having an outer end extending through the front end of the pen barrel and being longitudinally slidable in the barrel, the latch member being moved alternately upon successive reciprocations of the actuating element to a position in which it latches the writing unit in its retracted position and a position in which it allows the writing unit to project from the barrel. Two parts 10, 11 of the barrel are joined by a sleeve 12 in which the writing unit 28 is slidable. The front end of the barrel is tapered and a tubular hood 20 having lateral lugs 23 at its rear end is slidable therein. The barrel part 11 is formd internally with inwardly projecting lugs 14 and longitudinal deep recesses 15 therebetween. Each lug 14 has a longitudinal shallow recess 16 parallel to the recesses 15 and the recesses 15, 16 terminate at their front ends in shoulders 17, 17<SP>1</SP>. A lug 23 of the hood 20 slides in each of the recesses 15, 16. Each lug 14 is formed at its rear end with teeth 18, 19, one on each side of the recess 16 and the rear ends of the hood 20 and lugs 23 are formed with teeth 24. A tubular latch element 25 is slidably mounted in the bore of the hood 20 at its rear end and has four lateral lugs 26 each formed with a downwardly projecting tooth 27. The lugs 26 are slidable in the recesses 15 but are too long to engage in the recesses 16. The writing unit passes through the bores of the latch element 25 and the hood 20 and in the writing position the writing point projects from the hood. The unit is held in writing position by a strong spring 32 disposed between the sleeve 12 and an enlargement 29 on the unit. A weaker spring 33 is disposed between the enlargement 29 and a washer 34 resting on top of the latch element 25. A further weak spring 35 is disposed between the front end of the latch element and a shoulder 21 in the hood 20. In the Fig. 1 position the lugs 23 on the hood abut against the shoulders 17, 17<SP>1</SP>. in the barrel and the lugs 26 on the latch element are engaged in the deep recesses 15, the teeth 27 thereon contacting the teeth 24 on the lugs 23 in those recesses. In order to retract the writing unit the writing tip is pressed against a firm surface so that first the writing unit and then the writing unit and hood 20 together move rearwards in the barrel. Rearward movement of the hood 20 causes the latch element 25 to move rearwards until the lugs 26 are disengaged from the recesses 15. At this point the teeth 27, which are now free to rotate, slide down to the bottoms of the V- shaped recesses between the teeth 24 on the hood 20. When the pen is raised from the surface the latch element moves forward under the influence of the springs 32, 33 until the teeth 27 engage the teeth 18 on the lugs 14, whereupon the camming action between the teeth causes the latch element to rotate until the lugs 26 engage those parts of the lugs 14 adjacent to the recesses 16 and are there held by abutment with the vertical sides of the teeth 19. The latch element now acts through spring 33 to hold the writing unit in a retracted position while the hood 20 is again projected to its greatest extent by the spring 35. To project the writing point the hood is again pressed inwards so that those lugs 23 in the recesses 16 lift the lugs 26 of the latch member above the teeth 19. The teeth 27 again rotate and engage in the V-shaped recesses between the teeth 24 so that when pressure on the hood is released the teeth 27 engage the inclined sides of the teeth 19 and are rotated into registration with the recesses 15 again which the lugs 26 enter. In a modification, the spring 32 is disposed between the rear end of the barrel and the rear end of the writing unit. Specifications 748,897 and 854,313 are referred to.