US2474865A

US2474865A - Ball-point pen

Info

Publication number: US2474865A
Application number: US745590A
Authority: US
Inventors: Salas Jose Antonio
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-05-02
Filing date: 1947-05-02
Publication date: 1949-07-05
Anticipated expiration: 1966-07-05

Description

J. A. SALAS BALL-POINfl PEN July 5, 1949.

Filed May 2, 1947 INVENTOR. Jose Amoma Salas v H 7"TORNE Y Patented July 5, 1949 UNITED STATES PATENT "OFFICE BALL-POINT PEN Jos Antonio Salas, Caracas, Venezuela Application May 2, 1947, Serial No. 745,590

4 Claims. i

This invention relates in general to writing pens and in particular to pens having a ball point and includes correlated means designed to enhance the utility and to facilitate the useful life of such pens.

In general, ball pens are characterized by employing a relatively viscous ink as compared with the ink used in other types of writing pens. Such ink is characterized by flowing with difiiculty under gravity so that frequently the flow of ink to the ball stops even though the ink is not exhausted. Various means have been proposed to overcome this disadvantage but the means heretofore proposed have not been satisfactory.

One prior means has been a piston which was threaded into the upper end of the ink-containing cylinder. By applying pressure on the piston, the ink was caused to flow more readily. It is characteristic of liquids, however, that they cannot be compressed. Therefore, if by chance the small capillary channel leading to the ball point should become clogged, the pressure applied by such a piston will frequently cause the ink chamber to burst. It is well recognized that by a simple threaded screw, pressures of several thousand pounds per square inch can be obtained in such a hydraulic system.

The present invention has for its general object the provision of means for overcoming the disadvantages above mentioned in ball point pens.

A specific object of the invention is to provide a ball point writing pen with means to apply a yielding pressure on the ink in the pen to facilitate its proper flow to the ball.

It is a further object of the invention to provide a ball point writing pen having means to enable the user to test the level of the ink in the barrel.

It is a further object of the invention to provide a ball point writing pen having means to prevent the ink from leaking out when the pen is turned upside down.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

According to the present invention, there is provided a ball point writing pen having, in combination, an elongate ink container, a writing head incorporating a ball point closing one end of said container, a piston closing the upper end of said container, said piston having a vent therein communicating with a closed air chamber. When pressure is applied on the piston to compress the ink, the ink will rise through the vent tube and compress the air in the air chamchamber gives a measure of the amount of ink remaining unused.

For a more complete understanding of the nature and objects of the invention, reference should be had to the accompanying drawing in which i Fig. 1 is a side elevation, partly in section, of one embodiment of the pen of the invention;

Fig. 2 is a cross-section of the pen of Fig. 1 taken along the line 2-2 thereof;

Fig. 3 is a fragmentary view, in side elevation and in section, of a second embodiment of the D Fig. 4 is a fragmentary view, in side elevation and in section,.of a third embodiment of the pen; and

Fig. 5 is a fragmentary view, in side elevation and in section, of a fourth embodiment of the pen.

The essential principle of*the present invention is the fact. that the'pen comprises an elongate ink chamber adapted to hold ink and a memberarranged and positioned to be reciprocated in the ink chamber and cover the upper surface'of the ink.

The piston has an aperture or channel communicating with a closed sealed air chamber. Preferably the communicating channel is an elongate capillary tube open at both ends. The upper end communicating with the closed air chamber or the capillary may be bent into a U- shape with the lower end of one arm closed.

By way of illustration but not by way of limiting the invention, several specific embodiments will now be described.

Referring to Fig. 1, the pen comprises a writing head [0, havin a conventional socket l I at the lower end adapted to enclose a ball [2 with suflicient clearance to allow the ball to rotate therein and provided with an ink channel l3, the lower end of which communicates with the socket H and the top end communicates with a socket I l adapted to support therein an elongate container I5 adapted to contain the writing ink It. The head I0 is provided at its upper end with a threaded area 2| adapted to engage the lower threaded end 22 of the barrel 23. The barrel is 3 hollow through the major portion of its length and thus encloses the ink container l5.

In this embodiment the piston 16 conforms to the shape of the interior of the container and fits tightly therein and slidably engages the walls. The piston is preferably a block of material having one or more rings H of rubber embedded in the surface and contacting the walls of the container l5 and serving to make an air-tight and liquid-tight seal. It is essential that the piston fit very tightly. In the embodiment shown in Fig. 1, there is provided above the piston a sealed air space by means of an inverted cylinder ll threaded at its lower end to the upper end of the piston and having its upper end I9 closed. The piston is provided with an elongate hole into which is threaded a capillary tub? 24 open at both ends, the upper end being adjacent the closed end IQ of the tube l8.

In use, the pen shown in Fig. 1 is filled with ink and the piston inserted initially in the position shown. Whenever it is desired to apply pressure tothe ink, the barrel 23 is removed and pressure is applied on the piston by pressing downward on the tube 18. When the ink is thus brought under pressure, a small amount of ink will rise in the capillary tube 20 and compress the air in the closed container l8, thus relieving the pressure on the ink. As the ink is gradually used up, the piston is pressed further and further into the lower container IS. The height of the piston will indicate the level of the ink.

That embodiment shown in Fig. 3 is similar to that shown in Fig. '1 except that the capillary tube is bent into an inverted U. One leg, of the tube 24a is enlarged and sealed to provide the closed air chamber 25 while the other leg is open and passes through an aperture in the piston Ilia. When pressure is applied on the ink by pressing the piston liq. downward, the ink will tend to rise in the capillary and compress the air in tube 24a and bulb 25.

at mbodiment shown in Fig. 4-is also similar in construction to that shown in Fig. 1 except that the air tube I811. is fixed to the barrel 23o by means of the projection 26- which is threaded into the upper end 21 of the barrel 23a. In this embodiment the barrel 23a is not threaded to the lower container Iiiv but is ground to fit smoothly on and slide over the lower body of the pen as shown in the lower part of Fig. 4. To apply pressure to the piston, the barrel 23a is merely pressed downward toward the writing head. This tends to' shorten the pen but also gives a measure of the ink supply remaining. As in the other embodiments, the pressure thus applied will be relieved by the ink compressing the air in the closed chamber [8a.

That embodiment shown in Fig. 5 issimilar in tial portion of its outer surface, such threads 33 engaging the threads 32-. In operation, when the upper part of the barrel 230 is rotated, this will cause the threaded air chamber lBc to be moved downward, thus applying pressure through the piston I6 against the ink in the container I5, the pressure being relieved in the same manner asin the embodiment shown in Fig. 1.

I claim:

1. In a ball-point writing pen, the combinationof an elongate ink container, a writing head incorporating a ball point closing one end of said container. a piston closing the upper end of said container, a closed air chamber, and a vent in said piston communicating with said air chamber, whereby a yielding, pressure is applied to the ink in said container when pressure is applied to said piston.

2. A ball-point writing pen as claimed in claim 1, in which said air chamber comprises an inverted U-tube having one closed end and the other end communicating with said ink chamber.

3. A ball-point writing pen as claimed in claim 1, in which said air chamber comprises a cylinder having an upper closed end and the other end fixed to said piston, and said vent comprises a capillary tube passing through said piston and terminating adjacent the closed end of said cylindert 4. A ball-point writing pen as claimed in claim 1, in which said ink container and said air chamher are coaxial cylinders, one of said members containing threads on the inner surface and the other containing corresponding threads on the outer surface to permit one of said members to be screwed inside the other.

JOSE ANTONIO sALAs.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number- Name Date 498,213 Miller Ma 23, 1893 873,769 Morris Dec. 17, 1907 FOREIGN PATENTS Number Country Date 476,971 Great Britain 1937