US2730993A

US2730993A - Ink reservoir for ball point pen

Info

Publication number: US2730993A
Application number: US204754A
Authority: US
Inventors: Farnham F Boyle
Original assignee: RITEPOINT PEN AND PENCIL CO
Current assignee: RITEPOINT PEN AND PENCIL CO
Priority date: 1951-01-06
Filing date: 1951-01-06
Publication date: 1956-01-17
Anticipated expiration: 1973-01-17

Description

Jan. 17, 1956 F. F. BOYLE INK RESERVOIR FOR BALL POINT PEN Filed Jan. 6, 1951 INVENTOR. F. BOYLE FARNHAM States Patent om INK RESERVOIR FOR BALL POINT PEN Farnham F. Boyle, St. Louis, Mo., assignor, by mesne assignments, to Ritepoint Pen and Pencil Company, St. Louis, Mo., a corporation of Missouri Application January 6, 1951, Serial No. 204,754

2 Claims. (Cl. 120-424 This invention pertains to the structure of ball point pens and more particularly to an ink reservoir therefor, which may form part of a refill unit.

An object of this invention is to provide a refill unit having an ink reservoir in the form of an open end tube, such tube being of ample volume and at the same time having provision for preventing leakage of the ink from the open end.

In accordance with this invention, the ink reservoir is in the form of a rigid tube preferably of plastic. This tube is formed at one end with a head adapted to receive the ball point tip. Above this head the tube has a bore of non-circular cross section. In the illustrated embodiment, this bore has a plurality of internal ribs extending therealong. These ribs increase the perimeter of the bore and thereby the extent of the surface to which the ink may cling, without seriously reducing the volume thereof. Since the ink tends to cling to the wall of the tube, this increase in the surface to which it may cling serves to prevent it from leaking out of the open end of the tube.

A preferred embodiment of the invention is illustrated in the accompanying drawing, in which:

Fig. 1 is a longitudinal section of an ink tube embodying this invention;

Fig. 2 is a section on line 2-2 of Fig. l; and

Fig. 3 is a detail section of the open end of the tube before reforming.

In the embodiment illustrated, an ink reservoir tube 1 is provided, sized to fit into the barrel of the pen in the usual manner. This tube is of rigid material, preferably of plastic and is formed with a head 2 at its lower end adapted to receive a ball point tip 3. This assembly provides a refill unit for the pen. The bore of the tube 1 is non-circular in cross section as may be seen from Fig. 2. This section may have various shapes, the one shown being formed by an outer circular bore 4 provided with a plurality of internal ribs 5. Between the ribs 5 recesses or channels 6 are formed. As shown in Fig. l, the ribs 5 extend along a major portion of the length of the tube 1 except for an enlarged circular portion 7 provided to receive the tip 3. While in the drawing the tube is shown with six internal ribs, any other number may be used and the general form of the outer limit of the bore may be of non-circular form.

The ribs 5 terminate short of the upper end of the tube as indicated at 8 so as to leave the upper end open for the insertion of a plug 9 into the bore of the tube. This plug may be of any suitable material. It has been found desirable to make the same of resilient material, such as felt.

In the embodiment shown, the plug 9 is originally circular in outline and of a diameter somewhat larger than the inner diameter of the ribs 5. The plug is then pushed into the bore of the tube so as to be placed under compression at the ribs 5, the intermediate portions bulging into the spaces 6 as indicated in Fig. 2.

-ttented J Before insertion of the plug 9, the tube is filled with ink at a suitable viscosity and a rod 10 is also placed in the tube. This rod may be simply a length of wire of suitable diameter and is arranged so as to be imbedded in the ink in the tube. After inserting the charge of ink and the rod 10, the plug 9 is inserted and thereafter the upper end of the tube 1 is heated and swaged over as shown at 11 so as to close the upper end of the tube except for an opening 12 to admit atmospheric pressure.

The ink used to chargethe tube is preferably of a relatively high viscosity so that by its internal friction and its adhesion to the inner wall of the tube and the surface of the ribs 5, its flow along the tube is retarded sufiiciently to prevent leakage of the ink out of the opening 12. The plug 9 which is spaced a substantial distance from the opening 12 assists in preventing the flow of ink toward said opening. The spacing of the plug 9 from the opening 12 should be sutficient to prevent capillary creepage of the ink along the tube from reaching said opening.

The rod 12 is loose in the tube 1 so that it may move about as the position of the pen is changed in the handling thereof. Accordingly, the movements of the pen in handling will cause the rod to move both lengthwise and laterally in the bore of the tube. This movement provides an agitating action by the rod 10 which tends to break up any air bubbles which may form in the ink and assist in maintaining a uniform flow of ink to the ball tip 3.

It will be seen, therefore, that this invention provides a structure whereby an ink reservoir of relatively large ink capacity is provided, while at the same time the tendency for such a large volume of ink to leak from the open end of the tube is prevented, namely by the adhesion of ink to the internal surface of the tube, which surface is increased in extent over that of an ordinary circular tube by provision of the ribs. Since the adhesion of the ink is active throughout these surfaces, it will be seen that such adhesion particularly as assisted by the plug 9 will prevent a flow of ink sufiicient to run out at the opening 12. At the same time, the continual feed of ink to the ball point is assured by provision of the agitator 10 to break up air bubbles and provide agitation sufiicient to encourage movement of the ink toward the tip as it is used up in Writing.

Various changes may be made in the details of construction, within the scope of the appended claims, without departing from the spirit of this invention. Parts of the invention may be used without the whole and improvements may be added while retaining some or all of the advantages of the invention.

I claim:

1. In a ball point pen, an ink reservoir comprising a rigid tube having an internal tubular bore provided with an opening in the upper portion thereof, said bore having a plurality of substantially straight, radially inwardly projecting, axial ribs, said ribs being uniformly spaced from each other around the periphery of the bore so that the space therebetween will constitute straight axial grooves extending along a major portion of the length of said tube, and a plug engaging said ribs in said tube in the upper portion thereof thereby closing a major portion of said opening and forming in combination with said tube a plurality of air passages along said grooves thereby allowing air to enter into said tube below said plug.

2. In a ball point pen, an elongated ink reservoir comprising a tube having a substantially uniform bore formed with a plurality of longitudinally extending and alternately disposed substantially straight axially extending, uniformly spaced ribs and grooves extending therealong for a major portion of the length of said tube,

3 7 said tube having .a ,headithereon at one ,end thereof adapted to receive, a ball point tip, said tube having an opening at the other end thereof adapted to admit air to said tube, and a resilient porous plug in said tube spaced from said opening, said plug contacting said ribs but not the bottoms of said grooves thereby forming a plurality of air passages along said grooves to admit air at ali times to said tube between said plug and said ball point tip.

References Cited in the *file of this patent UNITED STATES PATENTS Stewart Feb. '3, 1881