GB688891A - Improvements in and relating to reservoir writing instruments - Google Patents

Abstract

688,891. Reservoir pens. COMPANIA URUGUAYA DE FOMENTO INDUSTRIAL SOC. ANON. Sept. 12, 1947. [May 13, 1946 ; June 3, 1946] Nos. 14406/46 and 16831/46. Class 146,(iii). An ink reservoir for a ball-point pen has a diameter of not more than 6mms. and is equipped with a piston which has a "bulk" density (i.e. including cavities therein) the same or nearly the same as the density of the ink and which is a close sliding fit in the reservoir, so that the piston floats on and moves along the reservoir, with the ink surface and prevents seepage of ink. The floating piston 4 may be hollowed out as shown and may have attached thereto or contacting it on the side remote from the ink a flaccid tubular bag 5. The latter is secured by a clip 6 at its open end to the outer wall 2, and prevents leakage of any ink which seeps past the piston. The inside of the tube is open to the atmosphere through a passage 7. The piston is conical at 4a so as not to trap any air when it is inserted in the ink. Further, the piston diameter may be decreased at the side remote from the ink (see Fig. 6), so that ink drawn into the gap by capillary forces does not reach the end of the piston. In all cases the arrangement is such. that the piston follows and remains in contact with the surface of the ink whatever the position of the pen. In place of the bag 5, an extra piston may be employed and may be lubricated with a high-viscosity lubricant ; it may contain an air passage leading to the inktrap space between the pistons. Alternatively, or in addition to the extra piston an absorbent pad may be used. In another construction, Fig. 6, the piston 22 floats on the ink in the non- writing position of the pen. It slides on a central capillary tube 24 leading to the feed duct in the point section 26. An air-hole 27 is provided above the piston 22 and an absorbent pad 25 prevents leakage. The point section may be formed as described in Specifications 564,172, 609,817 and 650,754 Inks. A suitable ink contains an oleaginous solvent (e.g. olein, castor oil, ricinoleic acid or a combination thereof), an adhesive thickener (e.g. colophony) and a dye (e.g. aniline). A small proportion of a metal soap (e.g. sodium oleate) may be added. Proportions are given. Specifications 573,747 and 621,847 also are referred to. Reference has been directed by the Comptroller to Specification 615,548.