GB633879A - Improvements in and relating to reservoir writing instruments - Google Patents

Abstract

633,879. Reservoir pens. MARTIN, H. G. April 19, 1945, No. 16738/47. Divided out of 633,821. [Class 146 (iii)] In a ball-point reservoir pen, pneumatic means are arranged to exert on the ink a pressure having a maximum value no greater than and preferably less than the capillary pressure in the gap between the ball and its housing. As shown, the reservoir 27 comprises capillary channels 34a formed on the surface of a core of synthetic resin enclosed in a sheath 32. At the inner end of the reservoir is attached a resilient bellows made of thin metal or comparatively stout rubber enclosing an air-chamber 29. When the barrel parts 30a, 30b are assembled, an initial compression is imparted to the chamber 29 so that the air therein exerts pressure on the ink. The required pressure may be ascertained by trial and error methods. In this construction the pressure decreases as the ink is used. If a constant pressure is required, the chamber 29 is loaded by a weight which operates only when the pen is in the writing position. Specifications 571,698, 573,747 and 633,821 are referred to. According to the Provisional Specification, pressure may be applied to the ink by a spring-pressed plunger. Further the reservoir may be a rubber bag or corrugated metal cylinder or a cylinder with a flexible diaphragm so that as the reservoir or a part thereof is compressed, the ink is urged towards the ball. Means may be provided for removing or applying the pressure at will. For example, fitting the protecting cap on the end remote from the ball may function to compress the reservoir directly or through a spring. Alternatively, the reservoir with the ball may be slidable in a casing against the action of a spring which applies pressure to the ink when presure is applied to the pen point in the act of writing. The reservoir may be in the form of an annulus comprising a collapsable bag and an internal tube and the bag when compressed may apply air pressure to the ink. Specification 629,226 is referred to in the Provisional Specification.