US2612867A

US2612867A - Fountain pen

Info

Publication number: US2612867A
Application number: US45776A
Authority: US
Inventors: Marlin S Baker; Harlan H Zodtner
Original assignee: Parker Pen Co
Current assignee: Parker Pen Co
Priority date: 1948-08-23
Filing date: 1948-08-23
Publication date: 1952-10-07
Anticipated expiration: 1969-10-07
Also published as: GB663951A

Description

Oct. 7, 1952 M. s. BAKER EIAL FOUNTAIN PEN 2 SHEETSSHEE'I 1 Filed Aug. 25, 1948 INVENTORS.

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Oct. 7, 1952 M. s. BAKER EI'AL FOUNTAIN PEN 2 SHEETSSHEET 2 Filed Aug. 25, 1948 Patented Oct. 7, 1952 Janesville, Wis., assignorsto- The Parker Pen Company,- J'anesville, Wis, a corporation of- Wisconsin Application August-23, 1948, Serial No. 45.776

This invention relates generally to fountain pens: and has todo particularly with a filling mechanism therefor of the type embodying a breather tube.

An object is to provide a fountain pen having a multiple stroke filling means embodying, anew and improved breather tube. construction.

Another object is" to provide a fountain pen having a multiple strokefilling" means ofyimprovedconstruction by which the, ink reservoir may be filled to maximum capacity with a; minimum number of filling strokes.

Anotherobject is to provide a fountain pen of the multiple stroke filling'typ having a breather tube soconstructed and arranged. that it facil-i tates theflow of ink intothe reservoir upon each stroke of the filling means and thereby contributes to increased eff ciency of the filling means.

A further object is to provide a fountain pen having a breather tube'of such construction that a relatively small quantity of ink is expelled from the pen upon each compression stroke thereby insuring maximum expulsion of air from the reservoir and consequently a maximum intake of ink upon each suction stroke.

Another object is to provide a fountain pen of the type employing abreather'tube, which pen embodies a new and improved arrangement for venting through the forward end of the breather tube the air space at the forward end oi the inlr reservoir, thereby to prevent expulsion ofink fromthe pen upon an increase in pressure of the air in the ink reservoir or decrease in the pressure of the surrounding atmosphere. I

Another object is to provide multiple stroke filling means having a breather tube which is ventedin its forward portion but which is'so constructed and arranged that a minimum quantity of air is forced through the vent and back into the reservoir during each compression stroke in the filling operation thereby insuring that-a maxi-- mum proportion of the air displaced during the compression stroke is expelled from the pen and a. maximum quantity of inkis drawn into thepen during the suction stroke.

Other objects will appear from the following description taken in connection with the appended drawings, wherein:

Figure 1 is a bottom plan view of a fountain pen constructed accordance with the invention with certain of the parts broken away and sectioned;

Fig. 2 is a longitudinal sectibnal view taken through the iorward portion of the pen of Fig; 1;

S-CIaims. (01-. 120-46) Fig; 3 is an enlarged longitudinal sectional view taken through the rearward portion of the pen of Fig. 1;.

Fig. 4 is an enlarged transverse sectional view taken along 11-min ofFig. 2;

Fig. 5- is an enlarged transverse sectional view taken along line 5'5- of Fig.- 2-;

Fig; 6-'-is an enlarged transverse sectional View taken along line 6-6 of Fig. 2;

Fig. 7 is anenlarged transversesectiona-l view taken'along line 7-4 of Fig. 3; and

Fig. 8 isan enlarged, fragmentary view of" a portion of the structure of Fig. 2.

- For the purpose of illustrating the present invention it is disclosed in connection with a fountain pe-n generally similar to that disclosed in the co-pending application of Kenneth Parker and Ivan D. Tefft', Serial No. 45,624, filed- August 23-, 1 94 8; for Fountain Pen, to which pen the presentihvention'isexcellently well adapted. However, it will be understood that the present invention is not limited to the details oithefo'un t'ai'npenshown and described herein but is excellently adapted for embodiment in fountainpens of other forms; For example, the novel breather tube arrangement of our invention may be embodied in other types of multiple stroke filling devices and including other arrangements for eff'ecting displacement of air from the reservoir. Also our breather tube arrangement may be employed with other typesoi feed means than that disclosed herein although it is especially efiective when combined-with a feed of the general type illustrated. I

Referring now particularlyto- Ffgs. 1 and 2; the pen includes a casing or housing formed by a barrel; ii) and a" forwardly extending hollow shell H which together surround and substantially inclose' the internal members of the pen. The shell and b'arre'l'preferably are formed of a suitable knownplastic- The-pen is provided interior- 1y with an ink reservoir I 2, a writing point or nib l3 (the extreme tip of which projects from the shell I'll, andafeed means connected between the'inlc reservoir: l2 and the writing nib for feedi-nginl': to the: latter, which feed means preferably includes; an. ink. governor or= overflow collector [4 for: controlling the feed of ink,- all of which elements. are more fully described hereinafter.

tubular body, which preferably takes the form of an externally threaded bushing or nipple [5, is provided for connecting a majority of the other members forming the pen and. for retaining them proper assembled relationship. The body l5; preferably formed of a suitable plastic,

is provided with a forward bore I 6 and a rearward bore I1, which may be smaller than the forward bore, and is formed with a plurality of different external diameters providing in efiect a plurality of longitudinally displaced sections of different diameters adapted to receive various of the pen members as hereinafter described. The reservoir I2 is defined by the rearward bore portion I I of the body I and by an elongate, flexible and resilient sac I3 having its forward open end receiving the reduced section I8. The sac I9, together with the rearward portion of the body I5 thus defines an ink reservoir of substantial capacity. In forming the sac preferably the forward open end is of somewhat smaller diameter than the remaining portion of the sac so that such reduced portion is stretched when applied to the section I8 and a tight gripping action of the sac on the section I8 is provided. While the sac I9 may be retained on the section [8 merely by its resilience, preferably it is secured to the section I8 as by fusing it thereto or by a known cement.

The sac I9 is formed of suitable material of sufficient resilience to remain in expanded condition except when forcibly compressed. The material is resistant to inks of the types commonly used, that is, both acid and alkaline inks and will not deteriorate or lose its resilience over a long period of use. Preferably, the sac is formed of material which is transparent or sufficiently translucent to permit the user to observe the level of ink therein as hereinafter explained. The sac is adapted to be alternately compressed and released to draw ink into the reservoir for filling the latter in a manner which will be understood as the description proceeds. The sac I9 may be provided with a plurality of spaced, longitudinally extending ribs I9a which project inwardly from the inner wall thereof and which effectively stiffen the sac to aid it in returning rapidly to its initial shape after compression and subsequent release of the compressive force.

For the purpose of protecting the sac I9 when the barrel ID has been removed for the filling operation (as hereinafter explained) in order to prevent accidental compression of the sac, a guard 29 is provided. The guard 29 is formed as an elongate hollow member open at its forward end and is telescoped over the sac I9 and the rearward end of the body I5. The open forward end of the guard 29 is secured to an intermediate section 2I of the body It of slightly greater diameter than the section I8. 'While the guard 28 may be secured in any suitable manner, it preferably is threaded onto the section 2I for convenience in assembly, although, it may if desired, be secured in other ways, as for example, by providing an annular groove (not shown) in the section 2| and spinning the material of the guard into such groove.

The guard is provided with an opening 22 to expose a portion of the sac I9 and to provide access thereto so that the sac may be compressed by the user. The finger opening 22 preferably is of such longitudinal and circumferential extent as to permit the sac to be compressed and collapsed to a substantial extent as hereinafter explained more in detail. The rearward end of the guard 20 is closed as by a button or plug 23 preferably formed of a plastic, and which serves to stiffen and reinforce the end portion of the guard 20 to prevent damage thereto such as might otherwise result should the 4 end he struck against another object or squeezed tightly by the fingers of the user.

The guard 20 preferably is formed of thinwalled material of suitable rigidity, and preferably a material which is relatively light in weight, and for this purpose preferably aluminumis employed, although other materials may be used. The guard 20.;is disposed close to but spaced from the sac I9 and in turn is disposed close to but spaced from the barrel I0 thus permitting the sac I9 to be of relatively large diameter without substantially increasing the overall diameter of the pen barrel I0. However, the spaces between the guard and the sac and between the guard and the barrel, respectively, provide dead air spaces which serve to insulate the contents of the sac from external heating ef-- fects such as the heat of the hand of the user. In addition, the external surface of the guard preferably is polished to provide a reflecting surface which reflects radiant heat. Accordingly, the contents of the sac are protected against sudden increases in pressure which might otherwise result from external heating effects and which might tend to force ink from the pen.

The sac may be compressed manually or by suitable mechanism but preferably a pressure bar 25 is provided for compressing the sac I 9 to a greater extent than would be conveniently possible were the sac compressed by direct errgagement between fingers of the user. The pressure bar is so formed that it extends over a substantial portion of the length of the sac and hence when the bar is depressed, it compresses a substantial portion of the sac and displaces, a relatively large amount of air. The pressure bar preferably is formed of resilient material .such as metal and includes a fiat body portion 26 and a hook-shaped end portion 21, which latter engages and is held between the inner walls of the guard and serves both to provide the necessary resiliency and to hold the pressure bar in position in the guard 20. To aid in retaining the hooked end, it is provided with spaced small prongs 21a which bite into the wall of the guard. The bar 25 is formed with an offset portion 28 adapted to enter and seat in the finger opening 22 to aid in maintaining the pressure bar in position. In addition, the offset is of such depth that the upper surface of the portion of the pressure bar which is exposed through the opening 22 is substantially flush with the adjacent surface of the guard and is in a position for convenient engagement between fingers of the user.

The barrel I9 is formed as a hollow member having an open forward end and is adapted to be telescoped over the guard 20 and a portion of the body I5 and thereby to inclose the guard 20 and sac IS. The barrel I6 is detachably connected to the body I5 in order to permit ready removal for the purpose of providing access to the sac for the filling operation. To this end the barrel is threaded at its open end onto a section 30 of the body I5 of slightly larger diameter than the section 2|. The barrel I0 is adapted to be screwed onto the body I5 with its forward limit of movement being determined by abutment of the end edge of the barrel I0 against a rearwardly facing shoulder 3I provided for this purpose. The rearwardly facing shoulder 3I may be provided conveniently by a portion of the rear face of a clutch ring 32 carried on the body I5 and securely retained in position thereon. The clutch ring 32 also may serve to retain a slip cap 33 in a. manner '4! adapted to fit in generally similar tothat disclosed and claime'din United States Letters Patent No. 2,278,901 granted April 7, 1942, to Marlin S. Baker. l The barrel I is provided with a vent opening 34, preferably located at its rear end,which maintains the airwithin the barrel and externally of the sac at atmospheric pressure. Therefore, no sudden change in the pressure of the air which is in' the space within the barrel and surrounding the. sac takes place-when the barrel is moved into "position surrounding the guardor is removed therefrom. Moreover, since the interior of the "barrel is continuoush vented to atmosphere,

there is no possibility of a pressure difierential being established between the air in the interior of the barrel and the atmosphere which might 'eause flooding or starving of the pen when used in writing or leakage during periods of non-use.

' The hollow shell II is secured on the forward section 35 of the body 15, which preferably is of less diameter than the section 39. Preferably, the shell I i is threaded onto the section 35 and abuts the clutch ring 32 to maintain it in firm abutment with the forward end of the section 38 of maximum diameter, the clutch ring being positioned on a portion of the body member 15 which is of the same diameter as the section 35 but preferably not threaded. The'shell preferably is ad- 'hesively secured on the body 15 by a thermoplastic cement which maybe softened by heat to permit removal of theshell for repair purposes. The shell is {to receive the governor l4, and a reduced bore 3'! formed with a chamber 35 adapted extending from the chamber 3B through the forward end of the shell i l, through which the nib l3 projects.

erally cylindrical body or core 38 having a plu- 'rality of longitudinally spaced, circumferential fihs' 39 extending radially therefrom and defining a plurality of circumferential, longitudinally :spaced capillary spaces or cells 413. The capillary cells 40-are so formed that they progressively increase in width toward the forward end'of the pen for controlling the flow of ink in a manner explained more in detail in said Baker Patent 'No. 2,223,541.

The governor i4 is formed with a shank pQition the bore It for supporting the overnor M on the body s, with the forward core portion and fins being disposed in the chamberdfi and substantially filling the same. The governor I4 is positioned in the body l5 by a shoulder 42 provided by the rearwardmost fin 43 which fin, as well as the forwardmostfin 44, may be substantially thicker than the remaining intermediate fins 35 for the purpose of increasing their strength." i v For the purpose of feeding ink from the reservoir II, a capillary'ink'feed duct is provided which takes the form of a fissure 45 extending longitudinally of the governor l4 and radially inwardly throughout the radial extent of the fins 35 and the core 38. The feed duct 45 has a rearward portion 45a which opens at its rear end into the chamber defined by the bore l1 and extends forwardly to the rearward cells 40, and a forward portion 45b of narrower widthv which extends to short'of the forward end ofxthe governor Id." The feed duct 45 which preferably is disposed in the "bottom portion ofthe governor l4 and intersects the fins 39 and the capillary cells 40 defined thereby. Thus-the capillary cells 4|] are in feeding communication with the feed duct 45 and constitute a capillary overflow space constantly in feeding communication with the ink feed duct 45 to receive ink tending to flow through the latter in excess of that required for writing purposes. The thicker fins 43 and serve to maintain the desired spacing of the opposed walls which define the feed duct 45 but, in order to aid in maintaining this spacing, aspacing pin 46 may be inserted in a suitable opening of the rearward end of the shank 4i.

The governor l4 is formed with an axial bore extending throughout its length and communicating at its rear end with thechamber defined by the. bore [6 and forming a portion of the ink reservoir. The bore :in the governor i4 is formed with a plurality of

portions

50, 5|, 52 and 68 of progressively decreasing diameters respectively from the forward end of the Collector 14 in a rearward direction. The forward bore portion'50 provides a socket for the writing nibl3 which preferablyhas a cylindrical shank portion53 frictionally fitted. into such socket. 'Theshank portion 53 is slotted in its-underside as at 54, and provided with a notch 55 forwardly for the slot to provide a passage for the entry of air into the reservoir, as hereinafter explained. The nib may, if desired, seat against therear wall of the bore portion 53in order to accuratelypositlon the nib longitudinally with respect to the associated pen members. The nib 13 has a forward'tapered writing end portion 56 provided with a longitudinal slit 5'! terminating rearwardly in a'pierce 58, the nib being of such length that when seated .in the bore portion 50 the writing tip projects Such ink feed means includes a feed bar 60 associated with the nib I3 and formed with a genorally cylindrical body portion 6| frictionally seated in thebore portion 52, and a reduced forward end portion 6-2 extending forwardly through the nib and providing with the adjacent wall of the bore 31 an air passage extending through the forward end of the shell H and communieating through the nib notch 55 with the chamber36 in the shell l I. The feed bar-'60 is of slight- 13; smaller diameter than the interior of the nib 13,- thereby providing between the nib and feed bar an ,arcuate capillary space 63 extending from the rear end of the nib to forwardly of the nib pierce 58. This arcuate space 63 communicates with an annular capillary ink space 64 defined by the bore portion 5| and the adjacent portion of the feed bar body 3|, which space 64 is in communication with the ink feed duct 45. Thus it will be seen that an ink feed passage is provided which provides communication between the reservoir [2 and the nib pierce 58 and slit 51. This feed passage functions in a manner-generally similar to that described in Baker Patent No. 2,223,541. However, in order to further insure that ink will be delivered by capillary action in the nib But, an ink feed Sin ll! of capillary Preferably, the bor 31 is slightly relieved or recessed above the nib I3, as at 65, to provide an arcuate capillary space extending over the nib and which receives ink through the pierce 58 in order to insure that a quantity of ink is maintained at the nib slit and the pen, therefore, is always in condition for instant writing.

Air to replace ink withdrawn from the reservoir in writing is admitted to the ink reservoir I2 by way of the cells 40 and feed duct 45, as explained in Baker Patent No. 2,223,541, the governor I 4 being provided with an air channel II (Fig. 4) in its top side, which channel is'of greater than capillary width and extends throughout the length of the collector and in intersection with all of the fins 39 and capillary cells 40, preferably at a point substantially diametrically opposite the feed duct 45. The air channel II communicates with the chamber 85 and thus with the exterior of the shell I I through the nib notch 55 and the bore 37.

For the purpose of providing for multiple stroke filling of the reservoir, a breather tube 61 of novel construction, arrangement and functioning is incorporated in the pen for performing functions enerally similar to those of a conventional breather tube. Thus the breather tube 61 communicates at its forward end with the feed means and at its rear end with the interior of the reservoir. Thus air is displaced from the reservoir through the breather tube upon compression of the sac, and upon release of the sac a suction is created which draws ink into the sac. Thus upon repeated filling strokes, each consisting of compression and subsequent release of the sac, ink is drawn into the reservoir in successive increments to fill the reservoir.

The breather tube 61 is securely seated in a bore 56 in the feed bar body as by providing slits 15 in the end of the tube, and extends rearwardly through the bore 68 and into the reservoir I2 and terminates at its rear end close to the rear end of the sac I9. The bore 66 is connected through a transverse passage 69 with the annular ink space 64 previously described and thus an air discharge path is provided by the breather tube 61, bore 65, passage 69, annular space 64, arcuate ink space 63, the forward portion of feed duct 45, capillary cells 40 and air channel ll through which air is displaced from the reservoir I2 during the filling operation as hereinafter described. The breather tube 61 is disposed axially of the body I5 and the sac I9 and, therefore, when the sac I 9 is compressed and partially collapsed durin the filling operation such manipulation does not bend or collapse the breather tube 61 and there is therefore no interference with the passage of air through the breather tube.

To fill the pen, the barrel I is unscrewed from the body I and is slid rearwardly to disassemble it from the remainder of the pen thereby to expose the finger opening 22 and render the pressure bar 25 accessible to the user. The forward end of the pen then is inserted in a supply of ink and the sac I9 repeatedly compressed as by repeated depression and release of the pressure bar 25. During the filling operation the pen may be held by grasping the shell at its rearward portion with one hand and by pressing on the pressure bar with the fingers of the other hand, but, owing to the provision of the rigid guard 20, the pen may be held solely by one hand and the sac compressed by the fingers of that hand. Upon each compression of the sac I9, air is displaced from the reservoir through the breather-tube 61,

and the air discharge path above described, and thence through the front end of the shell. At the same time, some air is displaced from .the reservoir through the rear end of the ink feed duct 4-5, capillary cells 40, and thence through the front end of the shell. Upon release of the pressure upon the sac, the latter returns to its normal expanded condition, whereby a suction action is produced which draws ink into the reservoir on a reverse direction along the path through which air was expelled during the compression stroke and principally through the breather tube. It will be understood that where any ink is in the pen at the beginning of the filling operation, some ink may be expelled with the air upon the first compression of the sac; also, ink may be expelled with the air upon subsequent compressions. However, the amount of ink drawn in during each expansion of the sac is greater than that expelled with the air during the-previous compression and therefore repeated compression and release of the sac I 9 fills the reservoir I2.

It will beunderstood that ink will rise in the reservoir until it stands at a level substantially even with the rear end of the breather tube. Thereafter, the only additional ink which can be drawn into the reservoir is an amount equal to that which is drawn in upon the next additional suction stroke. If further strokes are effected, no further ink will be drawn into the reservoir since upon each such additional compression stroke, ink instead of air is forced out of the pen and regardless of the number of such additional strokes, no more ink will be drawn in upon the expansion of the sac than is expelled during the compression of the sac. It will be noted, however, that the rear end of the breather tube extends to very close to the rear end of the sac so that the level of the ink at the end of the last effective filling stroke is very close to the rear end of the sac and the sac, therefore, is substantially filled.

Because the portion of the sac opposite the inner or rear end of the breather tube is exposed when the barrel is removed and the sac is transparent or translucent, the user may determine by inspection when sufficient ink has been drawn into the reservoir to raise the level of the ink to the level of the rearward end of the breather tube 61. The user thus is informed that the only further ink which will be drawn into the reservoir is that which will be drawnin by the next filling stroke and that only one such additional stroke is required to complete the filling operation. Thereafter the barrel is telescoped over the guard 20 and screwed home against the clutch ring 32 and the pen is ready for use.

In accordance with the present invention, the breather tube is made with a very small internal diameter and correspondingly small internal cross-sectional area. Therefore, only a relatively small quantity of ink stands in the breather tube .at any time and which must be displaced when the sac is compressed during the filling operation to expel air from the reservoir through the breather tube. Thus, upon each compression stroke a relatively small proportion of the combined volume of ink and air which is expelled through the breather tube consists of ink and a relatively large proportion of such volume is air, with the result that upon each filling stroke there is only a comparatively small loss of efiiciency tbecause of the presence of ink in the breather ube. 3

except the rearward few cells thereof, to drain back into the reservoir when the pen is maintained in point-up position. By reason of this tendency, the governor tends to be cleared of ink when the pen is maintained in point-up position and has a large proportion of its ink storage capacity available as stand-by space for receiving ink should ink tend to flow from the reservoir in excess of that required for writing. Therefore, unless it is desired to use the pen in writing immediately after filling it, there is no necessity for clearing the collector in the course of the filling operation as the collector will tend to clear itself when the pen is held in point-up position as it customarily is when carried in the pocket. Where it is desired to write with the pen immediately after filling,

the overflow ink storage spaces in the governor may be rapidly emptied of ink at the completion of the filling operation by removing the end of the pen from the supply of ink prior to the release of pressure upon the sac I9 after the last compression stroke. That is to say, when the user observes that the level of the ink has reached the height of the end of the breather tube, the sac is compressed an additional time and the pen is removed from the supply of ink, whereafter the pressure on the sac is released, which draws the ink from the overflow storage spaces into the reservoir. However, where the pen is to be carried in point-up position before being used, it generally is not necessary to perform such governor clearing operation because of the tendency for the governor to be cleared by drain-back.

In writing, ink finds its way from the reservoir 12 to the nib slit by way of the feed duct 45, the annular ink space 84 and the feed slit 10, as well as the arcuate ink space 63; ink also enters the space 65 above the nib as above explained. Air enters the reservoir l2, for permitting ink to flow therefrom, by way of the air passage provided between the feed bar 60 and Wall of the bore 31, the chamber 36, the air channel H, the rearmost capillary cells 39, and the portion of the ink feed duct 45a rearwardly of the capillary cells. As will be understood from Baker Patent No. 2,223,541, the capillary cells receive ink which flows from the reservoir in excess of that required for writing purposes and fill with ink, thus blocking the flow of air to the reservoir l2 and preventing further ink from being withdrawn from the reservoir until the cells are emptied. The cells are emptied either by writing out the ink therefrom or by the establishment of pressure conditions which cause the ink to be drawn back into the reservoir from the cells. Because of the greater capillarity of the rearward cells these remain filled with ink until the remaining cells are emptied and thus the entry of air into the reservoir is blocked until substantially all of the cells have been emptied.

The sac I9 preferably is formed of a material which is relatively non-wettable (hydrophobic) byinks of the type with'which the pen is to be used. Therefore there is substantially no tendency for ink to wet and adhere to the walls of the sac when the reservoir is depleted by writing. In addition the reservoir is formed without crevices or other formations in which ink would tend to remain. Thus, substantially all ofthe ink in the reservoir may be withdrawn when the pen is used in writing.

It is important that the dimensions of the breather tube and associated members he carefully selected having in mind the above-described construction and arrangement of such elements and the necessary relationships therebetween. Excellent results were obtained in one practical embodiment of a fountain pen embodying our invention, which pen was generally similar in construction to the pen shown in the accompanying drawings and comparable in size to fountain pens of conventional construction, by forming the breather tube 61 (see Fig. 8) with an internal diameter a of approximately 0.036" and an external diameter b of approximately 0.046. The vent T2 in the aforesaid breather tube was formed with a diameter c of approximately 0.0 0" although it has been found that excellent results may be obtained where this dimension is within the range of from around 0.014 to around 0.026". In the aforesaid pen the well "I5 had a diameter d of approximately 0.098", thus providing a wall-to-wall width e of approximately 0.026". This dimension may be varied somewhat but must be small enough to provide substantial turbulence and on the other hand, must be large enough to prevent the formation of a film of ink across the open end of the well. The vent 12 Was located approximately midway of the depth ,f of the well although excellent results may be obtained where the vent is located anywhere between such midpoint and a point spaced it" from the open end of the well where the well is formed with the above described diameter and wall-to-wall width. A pen of the foregoing construction and having its parts dimensioned as above stated may be completely filled with approximately six filling strokes. Where the vent 12 is formed of the smaller dimension, the pen may be filled with fewer strokes but where the vent is of larger dimension, a greater number of strokes is necessary.

It will be understood that the foregoing dimensions may be varied somewhat without departing from our invention so long as the relationships and principles of our invention disclosed herein are substantially followed.

Proper feed of ink from the reservoir I2 to the nib slit 51 is insured by forming the several portions of the capillary ink path between the reservoir and nib slit with such dimensions as will cause ink to be drawn by capillary action into the several portions of the capillary feed path and stand in a continuous column from the reservoir to the nib slit. As an example of the size of the various ink passages constituting the feed which have been found suitable for effecting proper flow of the ink, the capillary feed duct 45 may have a width of around 0.006" in its rearward portion 45a and around 0.005" in its forward portion 45?), the annular space 64 may have a radial thickness of around 0.006", the arcuate space 63 may have a radial thickness of around 0.0055", the capillary space 65 above the nib may have a width or thickness of around 0.005", and the feed slit [0 may have a width of around 0.007", although this dimension may be smaller. The nib slit 51 has the smallest capillary dimension and preferably is from 0.001 to 0.0015" in width to insure that ink is drawn therein and maintained therein at all times. The capillary cells are of greater cross-sectional dimension and lesser capillarity than the feed duct 45 with which they communicate so that ink will be drawn therefrom and into the feed duct whenever any ink is in the cells during the time the penis 13 in writing so that the cells are' emptied by writing out.-

From the foregoing, it will be seenthat; the present invention provides amultiple-stroke filling means which is simple in construction and highly efil'cient in operation. The provision of the very small internal diameter breather tube decreases the amount of inkwhich is displaced during the compression stroke, thereby increasing the efficiency of filling. At the same time by reason of the small internal diameter of the tube, a large proportion of the ink drawn into the pen in each suction stroke enters the reservoir.

The novel proportioning and arrangement of tnevent which is located inthe forwardv end of the" breather tube provides the desired so=called "airplane characteristic without materially-decreasing the efficiency of the: filling operation. Moreover, the .arrangement is such that while it substantially prevents any decrease in the efficiency' of the filling operation, on the other hand it does not impair the effectiveness of the venting: function necessary to prevent expulsion of ink from the pen.

By forming the breather tube of silver or its equivalent, a number of advantages are obtained in addition to those just above-mentioned. The tube may be formed of very thin-walled stock and thus even though the vent opening may be made with a small diameter it may nevertheless be made very short in axial length relative to its diameter. Accordingly, the tendency for a film to form across the vent is substantially eliminated. In addition the highly wettable nature of the tube walls further inhibits the formation of such film. Moreover, silver may be readily fabricated and does not deteriorate over a long period of use and does not contaminate ordinary inks.

We claim:

1. A fountain pen comprising an ink reservoir, a pen nib, feed means defining a feed passage connecting the interior of said reservoir and said nib, and filling means for displacing air from said reservoir including a breather tube fixed relatively to said feed means and communicating at its forward end with said feed passage intermediate the ends thereof and exteriorly of said reservoir and at its rearward end with the interior of said reservoir for venting air from said reservoir, said breather tube having a continuously open lateral vent in its forward portion and intermediate its ends, and means defining a restricted passage opposite said vent providing communication between said vent and the interior of said reservoir, said restricted passage being of sufficiently small wall-to-wall width to cause substantial turbulence of air therein upon actuation of said filling means and consequent displacement of air through said breather tube and thereby prevent substantial flow of air through said vent.

, 2. A fountain pen comprising an ink reservoir, a pen nib, feed means defining a feed passage connecting the interior of said reservoir and said nib, and filling means for displacing ink from said reservoir including a breather tube fixedly v secured relatively to said feed means and communicating at its forward end with said feed passage exteriorly of said reservoir and at its rearward end with the interior of said reservoir, for venting air from said reservoir, said breather tube being provided with a. continuously open lateral vent in its forward portion providing com-.- munication between the interior of said tube and said reservoir and having a diameter smaller than pen-comprising. an ink reservoir,

a pen nib, feed means including a governor hav-.

ing capillary ink storage spaces,v said feed m ans} defining a feedp-assage connectingthe interior of said reservoir andsaid nib and connected to saidspaces, and a breather tube communicating. at its forward end with said feed means; exteriorlly or" said reservoir and at its rearward end with the interior of said reservoir forventing, air fromsaid reservoir and having a side vent in its forward portion communicating with said reservoir,.said governor and breather tube forming a well opening? into said reservoir and receiving the. ventedportion of saidbreather tubev to limitthe flow, of air from said ventduring filling, said area-trier tube being formed of silver and providing surfaces which exhibit; a relatively high degree of wett'ability with liquid inks.

4. A fountain pen comprising an ink reservoir, a pen nib, feed means defining a, feed passage connecting the interior of said reservoir and said nib, a breather tube communicating at its forward end with said feed eXteriorly of said reservoir and at its rearward end with the interior of said reservoir, said breather tube having an external diameter of around 0.046, an internal diameter of around 0.036", a lateral vent in the forward portion of said breather tube of from around 0.014 to around 0.026" in diameter, and means defining a restricted passage of around 0.026" wall-to-wall width opposite the vented portion of said breather tube and connecting said vent and the interior of said reservoir.

5. A fountain pen comprising an ink reservoir, a pen nib, feed means defining a feed passage connecting the interior of said reservoir and said nib and including a feed member in the forward portion of said reservoir, a breather tube of substantially uniform diameter fixed at its forward end in said feed member and extending rearwardly in said reservoir with the forward end of said breather tube communicating with said feed passage exteriorly of said reservoir and the rear end opening into said reservoir, said breather tube having a lateral vent adjacent its forward end and said feed member having a bore defining a well surrounding the vented portion of said breather tube and providing a restricted passage from said vent to the interior of said reservoir.

6. A fountain pen comprising means defining an ink reservoir and including a hollow body member, a pen nib, feed means defining a feed passage connecting the interior of said reservoir and said nib and including a feed member having a shank seated in the forward end of said hollow body member and formed with a bore communicating with said feed passage and opening at its rearward end into the interior of said reservoir, and a breather tube extending into said bore and fixedly seated therein with the forward end of said tube opening into said bore forwardly of said seat and the rearward end opening into the interior of said reservoir, the portion of said bore rearwardly of said seat being spaced from the corresponding portion of said breather tube and providing a restricted passage opening into said reservoir space, said breather tube having a lateral vent opening into said restricted passage intermediate the ends thereof.

7. In a fountain pen, means' forming an ink reservoir, an ink feed means having a wall forming a trap or well connected to said reservoir, and filling mechanism including a silver breather tube with one end passing through said trap and connected to said feed means and the other end projecting toward the rear end of said reservoir, said breather tube being thin-walled with a small internal diameter and having a vent opening in that portion of said tube passing through said trap of less diameter than the internal diameter of the corresponding portion of said tube but greater than the wall thickness of the tube.

8. In a fountain pen, a writing nib, means forming an ink reservoir, an ink feed means including a well or trap directly connected to said reservoir and a feed passage connecting said well to said nib, and filling mechanism including a breather tube of uniform diameter having one end passing through said trap and connected to said feed means intermediate the ends of said feed passage and the other end projecting near the rear end of said reservoir, said breather tube 16 being thin-walled with a small internal diameter and formed of silver, said tube also having a small vent opening at a point located in said trap and discharging laterally thereinto.

MARLIN S. BAKER. HARLAN H. ZODTNER.

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

UNITED STATES PATENTS Number Name Date 723,726 Perks et al Mar. 24, 1903 2,375,770 Dahlberg May 15, 1945 2,398,521 Cloutier Apr. 16, 1946 2,428,863 Wing Oct. 14, 1947 2,521,657 Severy Sept. 5, 1950 FOREIGN PATENTS Number Country Date 3,451 Great Britain Dec. 24, 1862 325,142 Italy Mar. 1, 1935