GB1099569A - Writing instrument - Google Patents

Abstract

1,099,569. Retractable ball-point pens. H. BROSS. July 28, 1966 [Aug. 2, 1965], No. 34020/66. Heading B6P. The rear push-button 2 of a retractable ballpoint pen has a cam member 5 which is flexible in at least the radial direction with respect to the longitudinal axis of the pen. The toothed part 6 of the cam 5 co-operates guide edges formed by apertures or grooves in the barrel of the pen. As shown in Fig. 8, in the retracted position, the toothed part 6 is retained in topmost corner of the upper guide edge. On depressing the push-button, the cam 5 moves radially inwards by the action of the slope 6<SP>1</SP> on the internal barrel surface, until it can latch into the second groove or aperture defining the second guide edge. The return spring (4, Fig. 1) then urges the tooth 6 to ride up the second or intermediate guide edge to its upper corner, thereby latching the pen in the projected position. A second depression of the push-button 2 disengages the tooth 6 from the intermediate guide edge to latch it behind the lowest or third guide edge. Upon release of the push-button 2, the tooth moves up the third guide edge, and continues to move as indicated by the broken arrows, until retained in the retracted position defined by the top corner of the uppermost guide edge. In the case of a push-button which is allowed to rotate relative to the barrel, e.g. of circular cross-section, the cam 5 is formed with a certain amount of rigidity in the peripheral direction. However, with push-buttons that are not allowed to rotate, e.g. of square section (Fig. 5), the peripheral movement of the tooth 6 is allowed by peripheral bending of the cam 5. If, however, movement of the tooth 6 parallel to the longitudinal axis is required when the cam 5 is bent from its neutral position, longitudinal guide edges (13, Fig. 4) must be provided. Instead of grooves or apertures forming the guide edges, ever deepening steps may be provided on the internal surface of the barrel (Figs. 6 and 7), with a ramp leading from the deepest step to the shallowest step. It is stated in the prior art that the mechanisms described above are suitable for retractable writing instruments with pressure caps.