US 2594083 A
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April 22, 1952 F. v. SILVER BALL'POINT PEN AND CAP Filed July 8, 1948 Patented Apr. 22, 1952 UNITED STAT-Es Pn'flzlv'rA OFFICE BALLPOIN T PEN AND CAP Frank Vern Silver, Chicago, Ill.
Application July 8, 1948, Serial No. 37,544
3 claims. (ci. 12o-42.4)
This invention relates to an improved fountain pen and relates particularly to an improved construction for ball point type writing pens.
The ball point pen constructions heretofore known have been subject to certain inherent disadvantages. The most commonly experienced disadvantage is the failure, or partial failure, of the flow oi ink. The now failure generally occurs after the pen has not been used for some time and is generally caused by an air lock in the ink channel immediately adjacent the ball tip. During periods of non-use, the writing tip of the pen is generally inserted within the pen cap and carried in inverted position by means of a clasp aiiixed to the pen cap.
The inks used in ball-bearing type pens are viscous iiuds and are not susceptible to easy or ready flow. However, during non-use of the pen. when the pen itself is inverted, the ink tends to withdraw somewhat within its channel and to retreat from the immediate vicinity of the ball bearing. The distance the ink withdraws from the ball bearing dependsupon the viscosity of the particular ink used, temperature and atmospheric conditions, etc. When the ink has been withdrawn by reverse flow, its meniscus` will form at a point below the ball bearing in the ink channel and air will enter the channel between the ball bearing,r and the meniscus and thus forms an air lock.
When the pen is again held in writing position in order for the ink to flow evenly about, the ball bearing, this air lock must be broken and the surface tension at the meniscus of the ink column must be overcome.
In the ball-bearing type pens heretofore known, no enicient means for overcoming these obstructions to free ilow of the ink has been provided.
In accordance with the features of this invention, the aforementioned disadvantage is overcome by providing a ring seal member which embraces the ink cartridge and by providinga pressiitted cap to t over the ring and ball bearing when the pen is not in use. When the cap is being removed, its interior is sealed by the ring from the influx of air so that. a partial vacuum is created within the cap about the ball bearing until the cap is completely removed from the ring seal. The low pressure area or partial vacuum created within the cap during its removal induces the now of air from behind the ball and breaks the previously described air lock. It is a well known law of physics that fluids will tend to move from a higher to a lower pressure area and it is this law that is utilized in overcoming the resistance to the outward iiow of ink* brought about by the air lock and by surface tension.
It is, therefore, an object of this invention to provide an improved fountain pen construction.
Another object of this invention is to provide a ball point pen construction that provides an even, continuous flow of ink from the start when in use.
Other and further objects of the present invention will be apparent 'to those skilled in the art from the following detailed description of the annexed sheet of drawing, which by way of preferred example only, illustrates one specific embodiment of the invention.
On the drawing:
Figure l is a perspective view of an assembled pen cartridge and cap constructed in accordance with the features of the present invention;
Figure 2 is a broken vertical cross-sectional view to an enlarged scale, of the cartridge and cap of Figure 1; and
Figure 3 is an enlarged fragmentary cross-sectional view of the writing tip of the pen showing the ink channel to the writing ball bearing.
As shown on the drawing:
The reference numeral Ill indicates generally an assembled ball point pen constructed in ac.l cordance with the features of this invention. As seen in Figure l, the pen Iii comprises a cartridge casing I2 and a non-vented cap I4 forI covering and protecting the writing point of the pen dur ing non-use. The casing I2 and the cap I4` are of generally cylindrical configuration, the can I4 being tubular and so dimensioned as to telescopingly and snugly fit the casing I2 toward the writing end oi` the pen. The casing I2 is also hollow and tapped adjacent its open end to receive the pen cartridge, inf dicated enel-ally by the reference numeral I6. The cartridge I6 comprises a cartridge barrel IB having a reduced externally threaded end for threading within the casing I2 and a writing tip and channel member 20. The tip member 20 is tapered inwardly toward the writing end which provides a socket 20a for receiving a writing ball bearing 22. A centrally disposed longitudinal ink channel 24 runs the entire length of the writing tip and channel member 20, communicating with the socket Zla through the feeder channels 26.
The tip and channel member 20 has a reduced diameter stem 2Gb which fits into the hollow barrel I8 and is secured therein by the engagement of external threads 20c on the stem and internal threads l8a on the barrel I8 at the end adjacent the writing end of the pen. The stem 20h is open ended providing the channel 24 but the end portion is covered by a sleeve 28 provided to prevent excessive leakage should the column of ink lose viscosity and tend to flow. An air hole 30 is provided through the casing I2 adjacent the open end oi the. stem 24, and the sleeve- 2"! and stem 20h have a communicating aperture 32 so that air at atmospheric pressure is within the channel 24 at the end of the ink column opposite the writing tip.
A sealing ring 34 embraces the reduced and threaded end portion I8c of the barrel I8 and rests against the shoulder I8b on the barrel provided by the reduced end I8c. When the casing I2 is threaded over the reduced end I8c, it secures the sealing ring 34 in position against the shoulder Ib. The sealing ring 34 has a concave outer periphery 34a and presents two peripheral sealing surfaces 34h and 34e to the inner surface of the cap I4 when the same is pressed over the Y writing end of the pen as illustrated in Figure 2.
Contact of the cap I4 with the seal ring 34 and the casing I2 affords an air-tight iit of the cap over the writing end of the pen. The cap I4 has a pocket clasp 36 brazed or otherwise secured thereto in a manner so as not to permit the entry of air within the cap when the same is secured over the writing tip of the pen.
During periods of non-use, the pen is assembled with the cap as illustrated in Figures 1 and 2 and generally held in said position with the ball bearing Writing tip upward. Due to the forces of gravity, the viscous ink column will drop in the channel 24 and the meniscus M of the ink column may form well below the socket 20a and below the feed channels 20 as illustrated in yFigure 3. The meniscus M is formed in the manner illustrated due to the wall of the channel 24 being wetted by the ink uid and the forces of attraction o-f the particles making up the ink uid. This attraction force must be overcome in order for the ink to flow toward the ball bearing 22.
Also the gravitational pull of the ink fluid mass aids in the meniscus development and this force as well must be overcome in order to permit the ink to flow toward the ball bearing 22.
4 ends thereof, a closed end cap engageable over the ball end of the barrel and engageable with the seal with the open end extending past the same for an appreciable distance lengthwise of the barrel whereby withdrawal of the cap will attenuate the air in the same to create a partial vacuum" therein Ito unseat the ball and break an air lock formed by recession of ink from the ball due to the force of gravity when the pen is carried in upright or vertical position with the ball uppermost.
2. In a fountain pen, a cylindrical barrel, an ink feed channel therein vented to atmospheric pressure, a writing ball seated in the end of the channel to be wetted by ink flowing therethrough under force of gravity and movable from sealing relationship with its seat, a double ring seal projectingfrom the outer surface of the barrel intermediate'the ends thereof, a closed end cylindrical cap engageable over the ball end of the barrel with its interior` contacting the seal in sealing re-` lationship and extending for an appreciable distance, lengthwise of the barrel past the seal whereby withdrawal of the cap will attenuate the air within the cap and create a partial vacuum therein to unseat the ball and break an air lock Y formed by recession of ink from the ball due to feed channel therein vented to atmospheric pres- Air at the pressure within the cap I4 as sealed f bythe ring 34 is within the socket 28a and feed channels 26. The force exerted by this air pressure must also be overcome before the ink will again flow from the column 24 about the ball bearing 22 for writing purposes.
When the cap I4 is removed from the writing point, it is slipped from the casing I2 and ring 34, but during its removal and until its open end has slipped past the yring 34, the cap is sealed from sure, a ball seated in the end of the channel to be wetted by ink flowing therethrough under force of gravity and movable from sealing relationship with its seat, a cylindrical seal projecting from the outer surface of the casing intermediate the ends thereof, a closed end cap having a'cylindrical cavity therein engageable over the ball end `of the casing in sealing relationship with' the seal and extending there past for an appreciable distance lengthwise of the casing whereby withdrawal of the cap will attenuate the air within the cap and create a partial vacuum therein to unseat'the ball and break an air lock formed by recession of ink from the ball due to the force of gravity when the pen is carthe entrance of atmospheric air. Due to the increase of volume so produced within the cap a partial vacuum is created about the ball bearing and within the feed channels 26, which serves tobreak any air lock and to overcome the surface tension tending to resist now of the column of ink 24, and to thereby induce a flow of the ink toward the ball bearing 22.
It isv obvious, therefore, that the aforedescribed pen' structure incorporating the seal ring and press-fitting cap provides a ball bearing type pen having improved ink flowing characteristics.
It will be Vunderstood that modifications and variations may be eected Vwithout departing from the scope of the novel concepts of thepresent invention. ,r
Iclaim as my invention:
l. InV a fountain pen, a cylindrical barrel, an ink feed channel therein vented to atmospheric pressure, a ball seated in the end of the'channel to be wetted by'ink flo-wing therethrough under force of gravity and movable from sealing'relationship. with its seat, a ring seal projecting from vtl'iepouter surface ofA the barrel intermediate the Number Name Date 1,550,599 Y Walker Aug. 18, 1925i Y 1,863,061 Larsen June 14, 1932 2,223,541 Baker Dec. 3, 1940 2,278,907A Baker Apr. 7, 1942V 2,427,033 Wahl Sept. 9, 1947 2,449,939 Heyberger Sept. 21, 1948 2,452,504 Tefft. Oct. 26, 1948 2,474,996 y Wallis July 5, 1949 2,489,983 Severy Nov. 29, 1949 2,514,729 Snodgrass July l1, 1950 2,519,635 Claret Aug. 22, 1950 FOREIGN PATENTS Number Country Date 218,660 Switzerland Apr. 1, 1942 222,566 Switzerland Oct. 16, 1942 ried in upright or vertical position with the ball uppermost. FRANK VERN SILVER.
REFERENCES. CITED The following references are of record in the le of this patent:
' NITED STATES PATENTS 564,172.; Great ll` 1'"itain'.. Sept. 15, 1944