GB695861A - Improvements in reservoirs for writing instruments of the ball tip type - Google Patents

Abstract

695,861. Reservoir pens. COMPANIA URUGUAYA DE FOMENTO SOC. ANON. Aug. 13, 1949. [July 15, 1948; July 9, 1949] Nos. 19058/48 and 18218/49. Class 146 (iii)., A cylindrical &c. reservoir 1, Fig. 1, for a ball point pen, attached to a writing extremity 2 having a writing ball 3 therein, is provided with a buoyant sealing member 5 which is a sliding fit in the reservoir, follows the end of the ink column, and prevents escape of ink when the pen is inverted, and a non- buoyant balancing member 6 which sinks to the position shown during writing but, when the pen is inverted, descends through the ink to rest on top of the member 5 thereby preventing any tendency of the latter to rise in the ink and so prevent ink seepage. In the form shown in Fig. 3, the balancing element 6a is buoyant and the sealing member 5a is non-buoyant in the ink, so that in the writing attitude the element 6a will float on top of the ink and support the member 5a, and in the non-writing attitude the element 6a rises through the ink leaving the member 5a at the bottom of the ink column. The element 6a is a bubble of air or other gas in a film of synthetic resin, but it may be a gas bubble not enclosed in a shell, in which case the entry to the feed duct 4 must be small to prevent the air bubble entering it, or a porous filter &c. may be used at the duct entry of the kind described in Specification 650,804. Ink seepage due to capillary creep past the sealing member may be prevented by providing annular sharp-edged grooves in the inner surface of the reservoir near the open end thereof, as described in Specification 695,862. Further leakage preventing means include (i) a plug 7, having an air hole 8 therein, to close the end of the reservoir, which is preferably conically shaped ; and (ii) sharp edges 9 on the sealing members. Examples are given of preferred materials, weights, and dimensions of the various members. The ink preferably has a viscosity of 15 poise at 37 ‹C. Specifications 564,173, 571,698, 573,747, 621,847 and 695,861. also are referred to.