US2557563A - Ball point pen - Google Patents

Description

M. J. REED BALL POINT PEN June 19% 195] Filed Oct. 9, l94'7 Patented June 19, 1951 UNITED STATES FATE N or F BALL POINT PEN Maurice .1; Reed, Middletowii 'Towii'shfp, Mon= mouth county, N. J assighor'of thr-eigliths to Anne E. Reed and two-eighths to Thomas J: Eur'ell; II, both of Middletow-"n, N. J Application October 9, 1947, Serial No. 7%,967'

invention relates to writing instruments,

and is more particularly related to a pen of'the ball applicator type.

The ball point pen has undergone consider-' abledevelopment in recent years with the result that there is available on the present market a fairly large selection of such pens, varying considerably in details of construction and in cost. Despite variations in. the details of construction, these pens include in common a writing fluid supply conduit and a writing fluid applicator. In general, the supply conduit is an elongate hollow cylindrical body which may vary in cross section at various points throughout its length, but which terminates in a small capillary leading to and lying directly adjacent the other element of 'the combination, which is the ball applicator.

The ball is so mounted as to rotate when the pen is used so that while one surface of the ball is writing, another surface thereof is picking up writing fluid from the feed point of the supply conduit.

While pens of the foregoing type have enjoyed considerable commercial success, they are sub- ,iect to certain limitations which have prevented their more widespread use and which have caused dissatisfaction on the part of many of their purchaser's. For example, it has been found that these pens are not universally satisfactory with all types of writing materials, that they are susceptible of failure in operation, apparently caused by some interruption of the flow of writing' fluid to the ball applicator, and that when the initial supply of writing fluid with which they are provided for sale is exhausted, refilling by the owner is not possible. Thus it is that many of the advantages inherent in the ball point pen principle have not been heretofore fully enjoyed.

An analysis of the construction of the conventional ball point pen indicates that failure in operation resulting from interruption in the flow of the writing fluid to the ball point may, and probably does, result from the formation of air bubbles in the conduits of relatively small cross sectionwhich supply the writing fluid to the point of use.

The d'ifliculties which have been encountered in attempting to use ball point pens with all types of paperv apparently result from the'fact that the ball has a highly polishedsurface which does not afford sufilcient frictional engagement with hard surface papers, and consequently tends to limit the use of ball point pens in such applications as the writing of checks, notes and so on which are usually prepared on highly polished bank paper;

The problem ofrefilling the ball point pen is probably related to the first problem set out above; That is, the formation of air bubbles in the conduit leading to the ball point causes interruptions in the flow Of: writing fluid to the paint and consequently failure of the instrument 3 Claims. (01. 120-4214) n operates. Iii era-ems recmde ra'u'ure ini= tial operaticsn, the pen reservoir is filled under sufficient ressure so as to ins e that all air is expelled from the suppiy ecnduir through the bearing" spaces between the ban point main-e holdiflginediuiii. consequentl the writing fluid is applied under iiies'iiie 6r a niag'fn ude that the filling operation requires the use c: special tocis or iiistiiimnts which camibt be made available to the genera public at reasoiif able cost. some; of the manufacturers or ball point pens have attempted to overcoifie this di f ficiilty by providing cartridges efiect, constitute a ae'eiherit of a pt'rtiini 6f the pen itseif, these cartridges beihgfill'd the factory by the pressure methods outlined state. In view of the foregoing, it is an objeet or this acme the disadvantegescf' resenny available can point pens and w prov-i ea pen or that type wni h iscnare terlze'd tines: ddin from nterrupt on irithefiew 6f writifig'iidid to the tan seawater; whih is sfm with all t pes of writing rhatfial's, and which may he collvemen'uy and sat'isfaetarny refinedby the own i without recourse to factoi'y repiacemerit parts or expensive filiifig'equipniefit.

It is contempiated acccraifig is the present in: vention to provide a ball po nt pen] which is very reliable in operation regardless of the aper or other writing material with which it is used,

'and which is or" simple design susceptible of manufacture at relativelyl ow cost to precede a writing instrument of relatively high quality; I q Other objects and advantages of this invention will be @Pbfient upon consideration of theffcl; lowing detailed, description or, several riibddi ments thereof in conjunction with the annied drawings wherein: Figure I is a view in vertical section of a ban point pen cohstructd in accordance with the principles at the present invehtion; Figure 2 isa view in section taken along the lines 2-2 of Figure 1"; U M H Figure3 is a view in section taken along the lines 3-3 of; Figural Figure 4 is a vertical sectional view of a rese voircap modified from the type shown in Figure 1;

Figure Sis a vertical sectional view of a device constructed accordance with the principles of the presentinvention for fillingv the pen of Fig,- ure 1; and

Figure 6 is a view' partially in elevation and partially in vertical section of the-device of. Fig. ure 4' iri dperati veposition with respect to apen of. the type shown in Figure l I Now referring in greater detail to the drawings, and more particularly; to Figures 11, 2' and. thereof, the pen. there disclosed is-comprisedof a hollow cylinder assembly m; a ten-supporting: arid supplying assenitly l I a ball H lhdlilitdihtd 3 the assembly II, a reservoir cap I3, and writing fluid supplying conduits I I and I5. The hollow cylinder I is internally threaded at both ends and at the upper end the threaded zone I6 receives the threaded shank ll of the cap I3. The threaded lower portion of the cylinder I0 receives a threaded upper portion of the ball-supporting and supplying assembly I I. It will be noted that the assembly II is comprised of a piece of material having cylindrical channels therethrough which in Figure 1, are designated by reference characters I8 and I9. These channels merge at a junction point 20 above the writing ball I2. The writing ball is mounted in a socket in the end of the assembly I I for free rotation and a portion of its surface is-always in communication with the junction point 20 while another portion is always in writing position. In view of the fact that the ball socket must conform in a complementary sense to aportion of the surface of a sphere, it is convenient to divide the bearings for the ball into two sections, one of which is integral with the main body of the assembly II and the other of which, designated in the drawings at 2|, comprises a plate which may be separately machined and later applied to the end of the main body of the assembly to hold the ball in position. At the upper end of the channels I3 and I9 there is provided a cylindrical space of enlarged cross section in which the tubes I4 and I5 respectively are seated.

It will now be seen that a continuous channel for writing fluid is provided from the reservoir constituted by the hollow interior of the cylinder I0 through the top of the tube I5, throughout the length of the tube I5, through the channel I9, around the junction 20 at the top of the ball I2, through the channel I8, through the tube I4 and back to the reservoir. While structurally this passageway is comprised of separate parts in the form of the invention illustrated in the drawings, the important feature is that functionally the passageway is a U tube with the point of discharge of the writing fluid to the ball located at the bottom or point of maximum bend thereof.

It has been found that the location of the ball I2 at the point of bend of a'generally U- or V- shaped passageway overcomes the disadvantage of interruption of the flow of writing fluid to the ball caused by the formation of air bubbles in the feed lines. While the theory of operation is not fully understood, it is clear that by providing a passageway of U or V shape, serving the ball at. the point of bend, the component legs of the U or V passageway which accommodate the liquid, form columns of equal height in each tube much in the manner of the familiar manometer. Thus, each leg of the tube is under hydrostatic pressure equal to that of the other leg. Now, if this condition is prevailing and a bubble for some reason is introduced into one of the columns, as for example by shaking the pen, it is apparent that so soon as the pen reaches the writing position, which is more or less vertical, the hydrostatic pressure in the leg or column which does not have the bubble will exceed the hydrostatic pressure in the leg which does have the bubble, This will cause a movement of' the liquid and will cause expulsion of the bubble. Furthermore, it prevents the migration of a bubble downwardly toward the writing point which it is believed has been the cause of many failures of ball point pens as they were previously known. In the event of pocket pens which are usually carried in an inverted position in the pocket, it can be seen that any free space in the ink reservoir will be occupied by air and this air will tend to migrate to the apex or junction point 20 of the columns during the time that the pen is not in operative position. Thus, when the pen is once more restored to writing position, it may be that a bubble will exist right at the point 20 where the two columns run into one another, that is, just above the ball as is illustrated in Figure 1. It would seem that this bubble, being symmetrically distributed with respect to the two columns, would tend to maintain both columns with equal hydrostatic pressure and consequently would present a problem. In practice, however, it has been found that this is not the case, for any bubbles. formed at the point where the two tubes run into one another is in a highly unstable state of equilibrium and the slightest vibration or movement of the pen, which would naturally occur in attempts to write, causes the bubble to shift to one or another of the legs whereupon the phenomenon previously discussed takes effect and the'bubble is removed. It is further apparent that unbalanced equilibrium once established tends to be self-accelerating.

In view of the foregoing discussion, it appears desirable to construct the pen of the present invention with both of the tubes I 4 and I5 of equal internal diameter.

Regardless of the theory of operation of the present invention, it has been. found that if a ball mounted for rotation in bearings is served by two channels which merge above the point of feed to the ball, satisfactory operation results. It has been found desirable to have the cross section of the composite conduit or junction point immediately above the ball fairly large as is indicated in Figures 2 and 3. While the exact size may not be critical, it does not appear that the cross section should get substantially below the cross section of one of the conduits.

There is shown in Figure 4 a cap similar to the cap I3 which differs from the cap I3 in the provision of a small air vent aperture designated by reference numeral 22. The purpose in providin vent 22 in a cap, which in other respects is similar to the cap I3, is that as the writing fluid is consumed it is quite apparent that extra space is provided in the reservoir which must be occupied by air drawn in from the atmosphere. While under some conditions of operation and in some types of construction this air may be introduced between the ball and its bearing, during storage of the pen, there are other conditions where a vent in the cap is indicated, these being or including cases where the pen is to be subjected to long periods of continuous operation and cases where the ball fit is extremely close so that the ball cannot act as an air valve. In the case where the ball fits loosely and affords sufficient clearance so that air can pass between the ball and its bearings when the pen is inverted, and the pen is subjected to frequent inversion, it will be realized that each bubble of air which is disposed of in the manner described above will add to the air already in the space above the writin fluid in the reservoir. If this were to continue without venting, a pressure would build up to a suflicient extent as to cause the out-leakage of writing fluid at an undesired rate. It is therefore apparent that the aperture provided at 22 in the cap shown in Figure 5 affords a free and adequate pressure relief orifice. In other words, the aperture in the cap serves to maintain atmospheric pressure within the chamber above the writing fluid regardless of whether there is a tendency to inleakage or out-leakage of air.

The ball 12 shown in several figures of the drawing has not been heretofore described except to say that it is a sphere which receives the fluid from the junction point of the channels in the assembly H and applies that writing fluid to the surface to be marked. It has been found advantageous to provide the ball I2 with a microscopically roughened surface, and this may be done by subjectin the ball during manufacture to the action of an etchant. The eifect of microscopic roughening of the surface of the ball is to render the instrument better susceptible of use with very smooth writing surfaces such as hard finish papers, and to improve the lubrication of the bearin between the ball and the body I I. This is apparent when one considers that the roughening of the surface will increase the wetability of the ball so that the writing fluid distributed thereby will be in a better position to function as a lubricant between the ball and its bearing surfaces. Similarly, by the provision of roughening of the order which is produced by etching, it is apparent that a roughening approaching the type of roughness encountered in paper surface is achieved, with the result that better engagement between the paper and the ball occurs, which results in a better application of the writing fluid to the surface on which the mark is made and a more positive rotation of the ball with resultant regular replenishment of the coating of writing fluid on the ball. Furthermore, the roughened surface has increased ink-holding capacity.

If now reference is made to Figure 5, it will be noted that there is shown a collapsible tube 23 of the type used for dentifrices and the like, which is provided with a hollow threaded boss 24 at one end, the threads of which are complementary to and intended for cooperation with the internal threading at the top of the cylinder l0 of the pen. The collapsible tube 23 is provided with a cap at 25 which serves to protect the contents during storage. When the pen is to be filled, cap 25 is removed, the tube 23 is inverted and its threaded boss is inserted in the threaded end of the cylinder l9 whereupon it is screwed down sufficiently to hold it firmly in position, see Figure 6. Thereafter the tube is manually compressed and its contents are forced into the reservoir of the pen. It is apparent that during this operation a certain amount of air will have to be displaced from the pen reservoir as the writing fluid is placed in position. To facilitate this, the boss 24 on the end of the tube 23 is provided with an axially-extending groove 26 of such a depth that it extends below the root of the threads on the boss. It is therefore apparent that when the tube is in the filling position an air vent is provided along the side of the boss 24 so that the air displaced from within the cylinder can escape. No other precaution with respect to the filling of the pen of the present invention is required since the existence of an air bubble in any of the tubes leading to the ball is not a serious matter but is self-correcting in the manner described above. The cap 25 of the tube 23 can be provided with a sealing gasket 21 of conventional form which will seal ofi the groove 26 and prevent leakage of the contents of the tube while the tube is in storage.

While this invention has been described with respect to several embodiments thereof, it will be understood that these embodiments are by way of example and are not intended to be exhaustive or limiting of the invention. It will be apparent therefore that numerous modifications of the structure shown may be made within the scope of the annexed claims.

What is claimed is:

l. A writing instrument comprising a hollow casing, a ball mounted for rotation in one end of said casing, a writing fluid reservoir at the other end of said casing, means in said casing interiorly dividing the area above the ball into a plurality of conduits leading from a junction space immediately adjacent the ball to said reservoir, said conduits at the junction space being separated by a narrow lower edge of said means, said junction space being defined by the ball, the inner wall of the casing and said narrow lower edge of said dividing means and being materially in excess of mechanical clearance between said ball and said lower edge to afford free flow of liquid intermediate the conduits.

2. A writing instrument comprising a hollow casing, a ball mounted for rotation in one end of said casing, a writing fluid reservoir at the other end of said casing, means in said casing dividing the area above the ball into a pair of conduits divergent from a junction space immediately above the ball to said reservoir, said conduits being symmetrical on opposite sides of a narrow lower edge of said means which separates said conduits at the junction space, said junction space being defined by the ball, the inner wall of the casing and the narrow lower edge of the dividing means and being materially in excess of mechanical clearance between said ball and said lower edge to afford free flow of liquid intermediate the conduits.

3. A writing instrument comprising a hollow casing, a removable cap closing one end of the casing, a body closing the other end of said casing, said body including a portion projecting into the casing and a conical end projecting from the casing, a ball mounted in the conical end of said body, said body defining a junction space immediately above the ball and having a pair of channels therethrough extending from said junction space to the interior of said hollow casing, said channels being convergent toward the junction space and the body defining a narrow edge therebetween at the junction space, the junction space between said narrow edge and said ball being materially in excess of mechanical clearance and the space within the casing above the body functioning as a writing fluid reservoir.

MAURICE J. REED.

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

UNITED STATES PATENTS Number Name Date 600,299 Werner Mar. 8, 1898 720,705 La Burt Feb. 17, 1903 1,514,519 Harris Nov. 4, 1924 1,527,971 Forsell Mar. 3, 1925 2,397,229 Biro Mar. 26, 1946 2,408,256 Florman Sept. 24, 1946 2,411,532 Escofiery Nov. 26, 1946 2,424,896 Oakes July 29, 1947 FOREIGN PATENTS Number Country Date 364,359 Italy Oct. 31, 1938

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