Patent GB-748007-A (GB)
Title: Improvements in or relating to fountain pens
IPC: B43K7/10
Filed: 1953-03-04
Abstract: 748,007. Reservoir pens. PARKER PEN CO. March 4, 1953 [Dec. 4, 1952], No. 6084/55. Divided out of 747,968. Class 146(3) In a reservoir pen having a writing point and an ink feed passage which constitute a writing unit reciprocating relatively to a reservoir, and a pump member including a normally closed pump chamber which is opened and closed by reciprocation of the writing unit for pumping ink from the reservoir through the ink feed' passage to the writing point, means is provided for venting the feed passage to atmosphere. As described, the writing point comprises a rotatable ball but it could be a split nib. Inks of a wide range' of viscosity can be used and provision is made for preventing ink leakage due to atmospheric temperature and pressure variations. As shown, the pen casing comprises two portions joined by screw-threads, the rear portion being vented to atmosphere, and the removable cartridge reservoir is urged forwardly against a shoulder 21 by a coil spring. A metal nose bush 14 is screw-threaded into the front portion of the pen casing, and a point assembly 23 is slidably mounted in the nose bush 14. When pressure is applied to the point assembly 23, as in writing, the point is urged inwardly of the bush 14 to set up a pumping action which forces ink to the ball. The reservoir and pump unit is in a plastic or metal casing 25 closed at the rear end by a plug 26 which retains a long flexible sac 28 capable, in its free state of filling the interior of the reservoir chamber 29. When the reservoir is filled with ink, the sac 28 is collapsed, and due to the air vent 27 in the plug 26, the sac will expand as ink is withdrawn from the reservoir during writing. Secured within the forward end of the reservoir casing 25 is a holder 30 formed with ink passages 31 leading to a pump chamber 32 and supporting rigidly a valve stem 33 having a head 34. A rubber disc valve 40 is arranged loosely within a recess in the holder 30. A rubber pump member 45 is clamped between the holder 30 and an end sleeve 46 of the casing 25, the thickened wall 50 of the member 45 being engaged and distorted by the head 34 of the stem 33. The writing point 23, described below, has an extended sleeve 59 formed with an enlarged head 70 having an outer portion 71 formed with ribs 72 which surround the pump member 45, and engage frictionally therewith, and an annular rim 77 extending near to the front face 51 of the wall 50. Normally, the ink space 78 communicating with the writing ball 55 also communicates with the atmosphere through spaces, between the ribs 72, the space between the flange 71 and the sleeve 46, and slots 81 communicating with the air space around the reservoir. casing 25, all these spaces being of capillary size. When the writing point 23 is urged inwardly the rim 77 engages the face 51 of the pump wall to seal the space 78 from the atmosphere and the reduction in volume of the space 78 causes ink to be forced to the ball 55. Further rearward movement of the point 23 causes the face 51 to be pressed away from the rear face of the head 34 to establish communication between the space 78 and chamber 32 and a reduction in the volume of the latter. Some ink is thus forced from chamber 32 past the disc check valve 40 into the chamber 29 of the reservoir until the valve is forced against the wall of the holder 30, whereupon the ink in the chamber 32 is under pressure, and this pressure resists further rearward movement of the writing point 23. When pressure on the point 23 is released i.e. when the pen is raised from the writing surface, the pump 45 urges the point forwardly, ink flows from the reservoir into the pump chamber 32, the latter is then sealed by wall 50 and head 34, and the space 78 again communicates with atmosphere. Flooding or leakage due to increase in temperature and pressure is prevented since the space 78 is at atmospheric pressure and communicates with the atmosphere through capillary cells or spaces described above. The writing point 23 comprises a glass seat member 57 in which a sapphire ball 55 is retained by a soft metal sleeve 58. The ball and seat may be formed as described in Specification 747,968. An intermediate elongated plastic sleeve 59 fits between the seat member 57 and sleeve 58. A rod 63 is inserted into the bores of the sleeve 59 and seat member 57 to reduce the cross-section thereof. The metal sleeve 58 is deformed at 64 to grip the sleeve 59 and form a liquid-tight-seal, and is adapted tc slide within a bore in the metal nose bush 14. A split metal ring 68 limits the forward movement of the writing point. The sleeve 59, as described above, is enlarged at the inner end to co-operate with the pump member 45.