US3501225A - Fountain pen - Google Patents

Description

March 17, 1970 v 1.. P. MARTIN ETAL FOUNTA IN PEN 2 Sheets-Sheet 1 Original Filed July 22 1965 lullllllll IIIIIIIIIIII \i! u J 4 1 l l llllll III III March 17, 1970 L. P. MARTIN ETAL FOUNTAIN PEN 2 Sheets-Sheet z Original Filed July 22, 1965 United States Patent 3,501,225 FOUNTAIN PEN Lynn P. Martin and Thomas P. Evans, Fort Madison, Iowa, assignors, by mesne assignments, to Textron, Inc., Providence, R.I., a corporation of Rhode Island Continuation of application Ser. No. 474,083, July 22, 1965. This application July 19, 1968, Ser. No. 755,485 Int. Cl. B43k 5/18 US. Cl. 401-198 8 Claims ABSTRACT OF THE DISCLOSURE In a novel fountain pen having a vacuum type ink reservoir, a writing or marking point, and a capillary ink feed; an improved fluid control member arranged for releasably retaining ink to prevent leakage from the point in the event of excess ink discharge from the reservoir. The fluid control member comprises a porous plastic matrix, wettable by writing fluid, and defining a multiplicity of interconnected randomly disposed capillary storage cells of irregular configuration communicating with the atmosphere, with one another and with the ink feed means. The storage cells are lower in capillarity than the ink feed and normally remain free of fluid. In operation, ink is drawn from the reservoir by the ink feed and transferred directly to the point for deposit on a writing surface. In the event excess ink enters the feed, however, such ink will be transferred to the control member for retention in the storage cells until the feed requires additional ink for writing. As compared with the usual comb cut type control member, the present control member provides significantly greater fluid storage efficiency and is substantially less costly to manufacture while being considerably less susceptible to breakage during manufacture and assembly.

This application is a continuation of our earlier application Ser. No. 474,083 filed July 22, 1965 for a Fountain Pen, now abandoned.

This invention relates to a writing instrument and more particularly to a fountain pen having improved ink feed control means.

In the usual fountain pen construction, ink is contained in a reservoir the internal volume of which remains substantially constant during normal writing use of the pen. If continuous writing is to be realized, it is necessary to provide for the controlled entry of air into the reservoir to relieve the slight vacuum created therein by the withdrawal of ink therefrom during writing. This simultaneous but opposite flow of air into and ink out of the reservoir is generally accomplished through contiguous air and ink channels formed in or at least defined in part by a feed bar which extends between the reservoir and the point. The ink channel usually is formed as a relatively tight capillary slit or fissure in the feed bar with the air channel usually being the space immediately adjacent the feed bar. The air channel is small enough in cross section to support a column of ink but large enough to permit the movement of air bubbles therethrough.

Any air in the fountain pen reservoir will, of course, tend to expand if the pen is subjected to a temperature increase or an atmospheric pressure decrease. If such expansion should occur while the pen is held point downwardly, as in writing, ink may be forced from the reservoir in an amount greater than that which can be accommodated in the ink and air channels.

In the past, manufacturers have incorporated into their pens what might be termed an expansion chamber to control or accommodate such excess ink flow and to prevent 3,501,225 Patented Mar. 17, 1970 ice leakage of ink from the pen. The expansion chamber has customarily taken the form of a plurality of relatively large capillary size grooves or comb cuts machined in the feed or in a separate control member adjacent the feed, the grooves being arranged to communicate both with the ink feed channel and the atmosphere. With such a construction excess ink entering the ink feed channel will overflow into the expansion chamber grooves for temporary storage until such time as it is returned to the feed channel either for replacement of ink withdrawn during writing or for return to the reservoir after the inkexpelling pressure in the reservoir has been relieved.

Without question, known expansion chamber devices have proven to be of definite value in the fountain pen art, substantially reducing many of the severe leakage problems which were inherent in early day fountain pens. However, these expansion chamber devices have given rise to several additional problems which manufacturers have assiduously attempted to solve over the years without significant results, for present day fountain pens still utilize the same basic structures devised many years ago. For example, whether machined from hard rubber or molded from a suitable plastic, these expansion chamber devices are relatively expensive because of the complicated precision machinery, skilled workers and time consuming operations needed in holding the extremely close tolerances involved in their production. Moreover, even with the best manufacturing techniques and equipment, it is difficult to maintain these close tolerances, and any significant deviation in certain of the essential dimensions of these devices will often make the difference between proper and improper functioning of the pen.

Also, because of the fragile nature of the combs and other parts of the conventional expansion or fluid control devices, a high percentage of the devices usually are damaged either during processing or while being assembled into finished pens. Accordingly, not only is production time of highly skilled workers lost,'but such damaged controls cannot be even partly salvaged.

Another drawback to the usual expansion device is that a good percentage of its total volume is solid and therefore not available for holding ink. The high percentage of solid material in such devices serves merely as support for the capillary grooves so that the resulting structure will not be excessively fragile. Although manufacturers have tried in various ways to more efliciently utilize the volume occupied by the expansion device, very little progress has been made up until the present time. Thus, of the already limited available interior space in present day quality pens, a fairly significant portion thereof will be occupied by the expansion device which must be of sufficient size to provide an adequate reserve overflow capacity for the pen. Heretofore, if the size of the expansion device were to :be reduced to provide a desirable increase in the reservoir capacity, for example, a manufacturer would risk the creation of a condition which could lead to customer complaints because of leakage. With the usual fountain pen it thus has been a real problem to arrive at a satisfactory balance between reservoir and overflow capacities.

The present invention represents the first commercially significant improvement in fountain pen feed control systems since manufacturers adopted the concept of providing capillary overflow grooves many years ago. This invention not only eliminates or substantially alleviates the several problems discussed hereinabove but at the same time provides a significant reduction in both manufacturing and repair costs.

Accordingly, it is a principal object of the present invention to provide an improved feed control member for a fountain pen.

Another object of this invention is the provision of an improved feed control member which consists of a single part that may be easily and inexpensively manufactured.

It is yet a further object of this invention to provide a greatly simplified and completely reliable fluid control member having a multiplicity of overflow cells or chambers distributed randomly therethroughout.

A still further object of this invention is the provision of an improved fountain pen fluid control member consisting of a molded plastic matrix having distributed randomly therethroughout a multiplicity of intercommunicating capillary overflow cells adapted to temporarily hold excess ink discharged from the reservoir.

Yet another object of this invention is to provide a fountain pen of the type having a vacuum ink reservoir, the pen including a molded plastic fluid control member which is much less fragile than previous controls and has a very high ink holding capacity for its size.

A still further object of the present invention is the provision of a fountain pen having an improved fluid control member comprising a molded plastic matrix having distributed randomly therethroughout a multiplicity of various size intercommunicating spaces, a portion of such spaces serving as fluid transfer channels with the rest of such spaces serving as overflow storage cells for receiving and temporarily holding any excess ink discharged from the reservoir.

Yet an additional object of the present invention is to provide a fluid control member which is extremely simple yet highly eflicient, which is inexpensive yet reliable, and which can be routinely handled and assembled by the manufacturer without danger of damage thereto.

Still further objects and advantages of the present invention will be apparent from the following description and the accompanying drawings.

According to the present invention, there is provided a fountain pen having a barrel with a conventional ink reservoir disposed therein. Extending forwardly of the barrel is a writing point, which may be any one of several different kinds, and a capillary feed extends between and supplies ink from the reservoir to the point. Carried by the barrel adjacent the feed is a control member comprising a porous matrix which is wettable by the ink and which defines a multiplicity of randomly disposed ink storage cells communicating with the atmosphere and with the feed. These storage cells are lower in capillarity than the feed, and while they normally are not filled with ink, they have sufficient capillarity to support ink which might be received therein from the feed under conditions of excess ink discharge from the reservoir. Because of their lower relative capillarity however, any ink contained in the cells is released readily to the feed upon subsequent removal of ink from the feed, and thus the cells serve only to temporarily store fluid forced from the reservoir during such periods of excess ink discharge.

For a more complete understanding of this invention reference should now be had to the drawings, wherein:

FIGURE 1 is a longitudinal sectional view of a fountain type marking pen embodying the present invention;

FIG. 2 is a front end elevational view of the pen of FIG. 1;

FIG. 3 is an enlarged longitudinal view, partially in cross section, of the feed control member of the embodiment of FIG. 1;

FIG. 4 is a front end view of the fluid control member as shown in FIG. 3;

FIG. 5 is a longitudinal sectional view of the forward portion of a pen constituting another embodiment of the present invention;

FIG. 6 is a transverse sectional view of the embodiment of FIG. 5 taken along line 6-6 of that figure; and

FIG. 7 is an exploded perspective view of the feed and feed control member of the embodiment of FIG. 5.

Referring now to the drawings and more particularly to FIGS. 1 through 4 thereof, there is illustrated a fountain pen 10 having a generally cylindrical barrel 12 which may be molded of plastic. A forward barrel portion or gripping section 14 is threadedly mounted in axial alignment with the barrel 12, as by threads 16, to permit convenient disassembly of the barrel and gripping section for filling purposes.

As will be seen best from FIG. 1, the gripping section 14 is of a generally cylindrical configuration with a gradual inward taper toward its outer or forward end to provide a pleasing appearance and a comfortable gripping area for the user.

The ink or fluid reservoir in this embodiment is of the conventional vacuum type, consisting of a throwaway cartridge 32 which is molded of a plastic material having low moisture vapor transmission characteristics, such as polypropylene or polyethylene. This cartridge includes a cylindrical body portion 34 having one end closed by an integral wall 36, and the other end sealed by a closure plug or disc 37. Preferably, both ends 36 and 37 of the cartridge 32 are adapted to be pierced so that the user does not have to orient the cartridge when inserting it into the pen.

The inner end of the enlarged gripping section bore 48 is closed by a plug 38 having an enlarged rearward flange 40 which in the illustrated embodiment abuts against and seats on the rearward end of the gripping section. This flange 40 not only provides for the convenient positioning of the plug relative to the gripping section, but it likewise enables the plug to be sealed readily to the gripping section by spin welding should such sealing be desired.

Press fitted into a central longitudinal bore 42 in the plug 38 is a pierce tube 44 having a bias cut on its rearward end, this cut providing a piercing point 46 which is sufficiently sharp to penetrate either the wall 36 or the plug 37 of the cartridge 32 upon insertion of the cartridge into the pen for purposes of renewing the ink supply.

A centrally disposed longitudinal reduced bore 50 (see FIG. 2) extends forwardly from the large bore 48 of the gripping section 14, this reduced bore 50 terminating at the outer end of the gripping section to provide therein an open forward end. Extending radially into the bore 50 from the bore-defining walls of the gripping section 14 are several longitudinally extending splines or ribs 52 which serve to further restrict the effective diameter of the reduced bore 50.

While other types of points may be used with this invention, the point 54 in this embodiment is a substantially rod-like element of generally circular cross section and it is formed of a porous plastic material of the type disclosed in copending patent application No. 244,196, filed Dec. 12, 1962, the matrix preferably being a polyamide such as a fluorocarbon. The point 54 includes (1) a writing tip portion 56 which extends through the reduced bore 50 of the gripping section and forwardly therebeyond for writing purposes and (2) an integral rearwardly projecting elongate feed portion, which in the embodiment illustrated in FIG. 1 consists of an intermediate section 58 disposed in the bore 48 and a reduced section 60 which extends through the pierce tube 44 to adjacent the piercing point 46 thereof. Thus, the point 54 in effect constitutes a capillary ink conductor for feeding ink from the reservoir 32 to the writing tip 56, this feeding conductor comprisnig a multiplicity of interconnected pores ranging from about .001 inch to about .006 inch in diameter as measured by standard ASTM pore size determination methods.

Referring generally to the size of the pores of the point 54, it will be recognized that individual pores may vary in size either below or above the diameter mentioned heretofore, without any adverse effect on the performance of the point. However, for proper capillary feeding of the ink, a major portion of the pores should fall within or average close to the specified range when used with the standard type of aqueous based writing ink.

For best performance, it will be understood that the point 54 preferably should be manufactured of a material which is wettable by the usual wrinting ink or which can be made wettable either by treatment with a surface active agent or by exposure to the ink itself.

The point 54 is maintained in proper operating position in the gripping section assembly by means of frictional engagement of the Writing tip portion 56 thereof by the radially extending splines 52 in the reduced bore 50 of the gripping section 14. The diameter of the bore 50 is greater than the diameter of the writing tip portion 56 but the effective diameter of the bore 50 is actually reduced by the radial splines 52 to slightly less than that of the tip portion 56, so that the frictional engagement therebetween is tight. In spite of this tight frictional engagement between the splines 52 and the tip 56, venting from the atmosphere to the interior of the gripping section is provided through the bore 50 along the periphery of the tip 56 in the spaces between the splines 52.

Disposed within the gripping section 14 and arranged for fluid communication with the elongate feed portion of the point 54, is an improved fluid control member 62, this control member being generally cylindrical in configuration to conform to the interior surface of the gripping section bore 48. As will :be seen from FIGS. 1, 3 and 4 of the drawing, this fluid control member 62 includes a longitudinally extending central bore 64 which is slightly larger in diameter than the adjacent intermediate section 58 of the feed. For example, if the intermediate section 58 of the feed measures .075 inch in diameter, the bore 64 of the feed 62 preferably should be about .082 inch. Further, the diameter of the bore 64 preferably should be slightly smaller than the outside diameter of the pierce tube 44 so that the portion of the pierce tube 44 extending forwardly of the plug 38 may be press fitted thereinto (see FIG. 1). This latter feature is suggested primarily for convenience in manufacture as it will allow the plug 38, pierce tube 44 and control member 62 to be preassembled before insertion into the gripping section 14 as a complete subassembly. In this connection, it should be noted that the feed control preferably is short enough that it does not make contact with the rerawardly facing shoulder 66 formed by the intersecting forward and intermediate bores 50 and 48, respectively, of the gripping section 14.

From the above description, it will be seen that the feed sections 58 and 60 provide a fluid conductor for the direct transfer of ink from the reservoir to the writing tip 56, with a return air channel being provided through the bore 50 surrounding the writing tip 56, through the space between the forward end of the feed control 62 and the shoulder 66 and rearwardly along the feed portions 58 and 60 between their outer periphery and the inner surfaces of the adjacent feed control member 62 and pierce tube 44. Since ink will usually be present in the pierce tube, as writing progresses, a slight vacuum is created in the reservoir 32, which vacuum causes minute air bubbles to be drawn through the air channel just described to relieve this vacuum and permit continued feeding of ink from the reservoir for writing.

As discussed briefly h-ereinabove, the usual feed control member includes a plurality of machined comb cuts, or equivalent structure, for the temporary storage of fluid which might be forced from the reservoir as a result of a pressure increase therein. With the present invention, the complexity and high costs attendant to the manufacture of such control members have been eliminated while at the same time providing an increase in operating efiiciency and durability. These and other very significant advantages are realized by the provision of a feed control member consisting of a plastic matrix which defines therethroughout a multiplicity of randomly disposed ink storage spaces or cells which communicate with one another and with the atmosphere,

and which at least under conditions of flooding communicate with the feed conductor extending between the reservoir and the writing tip. As will be best seen from FIGS. 1, 3 and 4 of the drawings, communication between these cells and the atmosphere is provided through a generally semicylindrical venting channel 68 formed longitudinally along the length of the fluid control 62. This venting channel 68 then communicates with the atmosphere through the spaces :between the splines 52 surrounding the tip 56 in the reduced bore 50 as previously described.

The control member 62 is formed as a unitary homogeneous porous matrix of a synthetic plastic material of a type which is wettable or which can be made wettable by the usual fountain pen ink. Other materials can be used for this control member, including both inorganic and organic solid particles inert to ink and capable of being bonded or otherwise attached together, but polypropylene is preferred. The control member 62 consists of a multiplicity of particles of material which are bonded together at their points of contact, the size of these particles being chosen to provide the cell dimensions discussed in more detail hereinbelow. As one example of a process of forming these particles into a control member, they may be lightly packed into a molding die of the desired configuration with the die then being heated sufficiently to cause softening and subsequent bonding together of the surface contacting portions of the particles. Upon subsequent cooling, the particles remain bonded together to form the necessary unitary homogeneous porous matrix. The amount of heat used in this process depends, of course, upon the particular material chosen for the particles, as the heat employed in melting the exterior surfaces of one type of material may cause insuflicient or alternately complete melting of another material. Thus, for the particular particulate material chosen, it would usually be necessary to conduct a few routine tests to determine the amount and time of heating and the pressures needed for the initial light compacting of the particles.

The spaces in the feed control member 62 are randomly distriubuted and of various sizes. The total volume of these spaces, herein referred to as void volume, is preferably in the range of about 40% to about 75% of the total volume of the control. If the void volume falls below about 40% the capacity of the feed is generally considered too low, and if the void volume exceeds about 75 with present materials and methods the supporting structure appears to be too fragile. A certain percentage of these spaces or voids, ranging from about 10% to about 60% of the total spaces, comprise fluid storage cells the width of which range from between about .01 inch to about .07 inch. Cells within this size range fill with fluid only during periods of excess ink discharge from the reservoir 32, and subsequently release such fluid readily to the higher capillarity of the pores of the point 58 either during subsequent writing or as fluid is pulled back into the reservoir upon reduction of the pressure therein.

The Width of the fluid conducting smaller spaces in the fluid control 62 may range from about .001 inch to about .01 inch. These smaller spaces form a vein-like network of capillary passages through which ink is removed as rapidly as it is exuded from the intermediate section 58 of the feed during periods of excess ink flow or flooding. By means of the smaller spaces in the fluid control, ink is efficiently distributed throughout the control member 62 to the storage cells 67. This vein-like I It will be understood by those in the art that the dimensions of the spaces in the point 54 and in control member 62 may have to be varied, depending upon the character of the ink used in the pen, and Wettability characteristics between the ink and the porous matrix. However, with a control member having proper Wettability and the usual aqueous based ink having a surface tension ranging from about 40 to 60 dynes per centimeter and a viscosity of about 1 centipoise, the above discussed sizes have proven satisfactory.

Depending upon the material chosen for use in forming the matrix of the control member 62, the finished control may have to be treated to improve its Wettability with the ink to be used in the pen. For example, it has been found that a polypropylene matrix should be treated with a surface active agent to insure proper operation when initially put into use. One such suitable agent may be prepared as a solution of 99% water, .5% Span 80 (sorbitan monooleate) and .5% Tween 80 (polyoxyethylene (20) sorbitan monooleate) which are products of the Atlas Chemical Industries, Inc., of Wilmington, Del. It has been found that immersion and agitation of the fluid control 62 in such a solution, and subsequent drying, will give a surface which is quite satisfactory insofar as Wettability is concerned. Alternately, it has been found that a polypropylene control member can be made adequately wettable by immersion thereof in the writing fluid with which it is to be used for a period of several days.

Wettability of a particular material by a specific liquid generally is defined by a contact angle designation. It has been found that the contact angle of certain inks having a surface tension of between about 40 and about 70 dynes per centimeter will form a contact angle on a clean solid polypropylene surface of about 80 to 100. The contact angle on the small particles used in making the untreated polypropylene controls as discussed above is more difficult to establish, but it is believed to be in the same area of 80 to 100. This would appear to be too high an angle for proper initial Wettability of the controls, and a reduction therein, by a surface active agent or lengthy immersion in the ink, is believed desirable. A contact angle of below about 50 would appear to be suitable for the present controls, although, of course, the angle should be brought down as much as possible.

As will be understood from the above description, the present embodiment operates in its feeding and venting in much the same way as a regular fountain pen with ink being withdrawn from the reservoir through the feed or point 54 for deposit on the writing surface and with air entering the reservoir through the previously described vent channel to replace the fluid thus used. Should expansion of air occur in the reservoir when the pen is held downwardly, excess ink will be exuded from the feed and forced into the space surrounding the feed. This excess will quickly transfer to and throughout the fluid control member 62 passing by way of the smaller veinlike spaces to the larger fluid storage cells thereof. During this transfer and distribution, air displaced from the control member will be vented to the atmosphere through the venting channel 68 and thence through the spaces in the bore 50 surrounding the writing tip 56. The ink thus deposited in the storage cells will be safely retained against loss until such time as it is withdrawn back to the writing point either during subsequent writing or as the air in the reservoir contracts and the pressure therein is thus relieved.

Referring now to the embodiment of FIGS. 5 through 7, there is disclosed a fountain pen 100 having a feed control member similar to that described hereinabove with respect to the first embodiment, except that the control member is used in conjunction with a slitted metal point and a hard rubber feed of the usual type.

This modification consists of the fountain pen having a barrel 102 with forwardly disposed internal threads 104 for engagement with a rearwardly extending reduced threaded portion 106 of the gripping section 108. The barrel 102 and gripping section 108 may be molded of a suitable synthetic thermoplastic resin.

As will be noted, the barrel 102 has an enlarged intermediate bore 110 of about the same diameter as the rearwardly opening enlarged bore 112 in the gripping section 108. The barrel bore 110 and gripping section bore 112 thus comprise a cavity for the reception of a throwaway type ink reservoir or cartridge 114 which abuts rearwardly against the barrel shoulder (not shown). It will be understood, of course, that other reservoir arrangements may be utilized in this pen, such as a plunger or lever filling mechanism of the usual type, but for simplicity purposes a cartridge reservoir has been illustrated.

The gripping section 108 preferably is generally circular in cross section, with a gradual inward taper toward the front of the pen and a generally hooded design for convenient gripping and an aesthetic appearance. Internally, the gripping section is provided with an intermediate bore 118 extending forwardly of the rearward bore 112 to provide a rearwardly facing shoulder 120. As will be noted particularly from FIG. 4, the bore 118 tapers inwardly somewhat toward the forward end, terminating in a further reduced forward bore 122 which extends through thef orward end of the gripping section.

A plug 124 is press fitted into bores 112 and 118, the plug including a rearward enlarged flange 126 adapted to abut the gripping section shoulder for positioning purposes. The earward face of the plug includes a screw driver slot 128 for purposes of orientation of the plug as well as for use in spin-welding the plug to the gripping section should such attachment be desired by the manufacturer. Extending rearwardly of the plug 124 is a pierce tube 126 which, while being illustrated as integral with the plug, nevertheless may be of a type adapted for assembly with the plug in a manner well known in the art. Further, if the plug is of a molded type, it may be desirable for the manufacturer to provide an annular cut or indentation 130 extending rearwardly from its forward face, this out not only serving to reduce the amount of material in the plug but also to provide some resilience in the plug 124 for providing a good press fit in the bore 118. The pierce tube terminates on its rearward end on a bias cut providing a piercing point 132 which will penetrate either end of the reservoir cartridge 114 upon assembly of the cartridge into the pen.

The feed bar or feed means 131 in this pen includes a forward head portion 134 having an enlarged annular flange 136 adapted to abut and position against the rearwardly facing shoulder 138 formed at the intersection of the gripping section bores 118 and 122. Extending forwardly of the flange 136 is a generally circular tapering nose portion 140 having a land 142, the purpose of which will be hereinafter more fully described.

Extending rearwardly of the head portion of the feed 134 is a substantially cylindrical hollow tail portion 144, the upper surface of which has a longitudinal slot 146. As will be noted, the tail portion 144 extends rearwardly into a forwardly facing opening 148 in the plug 124 to thereby align with the pierce tube 126 and to provide with the pierce tube a continuous conduit through the pen from the bias cut end of the pierce tube 126 to the nose portion 140 of the feed 131.

Mounted in this channel formed by the pierce tube and feed tail is a feed insert 150 which is provided with a longitudinally extending flattened bottom area 152 (see FIG. 6) and a contiguous capillary fissure 154 which extends upwardly from the flattened area 152. This fissure 154 is cut completely through to the top of the insert at the forward end of the insert 150, but is not cut com pletely through in the remaining rearwardly extending portion of the insert. It will be noted that the insert 150 is positioned in the upper portion of the feed tail 144 to close slot 146 except for communication through the fissure at the forward end of the insert.

A capillary slit 156 is formed adjacent the forward end of the feed nose portion 140. This capillary slit 156 communicates with the capillary fissure 154 in the insert 150 to provide a continuous capillary fluid channel from thelnose portion 140 of the feed to the ink reservoir 114.

Disposed on the land 142 of the feed head 140 is the rearward or mounting portion 158 of a pen point 160. This pen point is preferably formed of a gold or stainless steel alloy and. provided with a forward writing tip portion 162 having the usual capillary slit formed between two relatively flexible nibs.

The point 160 is held in proper operating position by a press fit between the interior surface of the gripping sectiofi forward bore 122 and adjacent surfaces of the feed land 142, with sufficient space being provided between the nibs-of the point and the interior of the gripping section to permit a limited amount of flexure of the tip 162 during writing use.

As heretofore described this pen operates in a conventional fashion, fluid being drawn from the reservoir and into the capillary fissure 154 of the insert 150, then being transferred to the capillary slit 156 of the feed and finally to the capillary slit of the writing tip 162 for deposit on a writing surface. As such feeding occurs, air is drawn into the reservoir through an air scoop 164 in the head 140, then through a transverse aperture 178 in the lower section of the feed extension 144 and finally through the enlarged air passage 166 formed between the flat area 152 of the insert 150 and the internal surface of the extension or tail 144.

Disposed in the intermediate bore 118 of the gripping section 108 and in surrounding engagement with the feed tail 144 is an improved feed control member 170 constrticted according to the present invention. As will be noted from the drawing, this control member 170 is generally cylindrical in configuration, tapering slightly toward the front to conform with the tapering internal configuration of the intermediate bore 118. The internal bore 172 of the feed control member 170 preferably is of about the same diameter as the diameter of the feed tail 144 whereby the control member 170 can be pushed onto the feed tail 144 and into engagement with an abutment 174 onthe head 140 for positioning purposes, and the feed 131, the writing tip 162, the insert 150 and the control member 170 may be assembled into the gripping section 108 as a complete subassembly.

The control member 170 is similar in structure and function to the control member 62 of the previously described embodiment illustrated particularly in FIGS. 3 and 4. Basically, this control member comprises a homogeneous porous matrix formed of a synthetic plastic material preferably, but not limited to, polypropylene, the material being nonreactive with but wettable by the usual writing fluid. If necessary, this wettability can be improved in the various ways previously discussed.

As with the first embodiment, the control member 170 defines a multiplicity of randomly disposed fluid storage cells ranging from about .01 inch to about .07 inch in width. As will be understood, these cells are substantially lower in capillarity than the capillary fissure 154 of the insert 150 and, therefore, will not draw fluid from this feed fissure during normal use of the pen. Thus, except perhaps for the tight capillary dimensions at the juncture of the particles forming the cells, the cells will be clear of fluid and available for accommodating any discharge of excess fluid from the reservoir into the capillary feed fissure 154 and air channel 166. In the event of such a discharge, excess ink will be forced through the fissure 154 of the insert 150 and into the groove 146 of the feed extension 144 from where it will be picked up by the feed control member 170 and distributed rapidly therethroughv of the head portion 140 of the feed which, in turn, is in '10 out to the storage cells by the small vein-like network of cells of higher capillarity interspersed between the storage cells.

It will be understood, of course, that it is preferable to provide as many storage cells as possible in the fluid control 170. Depending upon the manner in which the control member 170 is made, and the particulate mate'- rial used in forming the matrix, the percentage of such storage cells (of a size between about .01 inch and about .07 inch in width) generally will range from between 40% to about of the total void volume of the control member. Generally, however, such storage cells will range between about 50% to about 70% of the void volume of the control. The rest of the void volume will consist of the smaller spaces, which generally range up to about .01 inch in diameter. The total void volume will range from about 40% to about 75% as indicated for the feed control 62 of the previously described embodiment.

Depending upon their size, a portion of the smaller spaces may remain at least partially full of writing fluid during normal usage of the pen. And while this factor will somewhat reduce the ultimate capacity of the control member 170; these pre-wet or prefilled spaces have the advantage of permitting more rapid removal and transfer of ink than would otherwise be realized. Also, they are believed to insure better and more rapid distribution of ink throughout the control member 170, especially to the upper or rearward end thereof, which is highly desirable in a structure as illustrated where communication between the feed fissure 154 and the control member 170 is restricted to one end thereof and a fairly long distance must be traversed by the ink to fill the storage cells at the opposite end of the control member 170.

It will be understood that the storage cells have to be in communication with the atmosphere and in the present embodiment such communication is provided by the venting channel 182 which runs the full length of the control member 170. This venting channel is in communication with the air scoop 164 formed along the lower surface direct communication with the atmosphere.

As Will be understood from the above description, the operation of the pen might be considered conventional to the extent of the feeding of fluid from the reservoir to the point and the return of air to the reservoir to replace fluid used during writing. However, the structure provided for accommodating excessive ink discharge from the reservoir is greatly improved over the usual prior art devices. This fluid control member provides a number of unique new advantages and features. For example, it is manufactured in a very simple, inexpensive mold; it uses a minimum of material, consisting principally of storage spaces; it requires no subsequent machining; it can be inspected very readily for quality control purposes, having no intricate combs, fissures, etc.; it can be handled and assembled with little or no danger or breakage or damage; and, it is highly efiicient whereby for a given amount of space, it Will provide a greater storage capacity than the usual control member.

It will be understood from the above description that the present invention is not to be limited to the embodiments herein described but that it is applicable to other types of writing instruments and similar devices.

What is claimed is:

1. In a fountain pen having a barrel with a vacuum type ink reservoir therein, a point extending forwardly beyond said barrel, and a feed defining a capillary conduit for supplying ink from said reservoir to said point; a control member carried by said barrel forwardly of said reservoir, and control member comprising a matrix (1) wettable by said ink,

(2) provided with a transfer surface disposed adjacent to said capillary conduit, and

(3) defining a multiplicity of ink storage cells.

(a) of irregular configuration, (b) communicating with one another, (c) randomly distributed throughout said matrix, ((1) larger in width and lower in capillarity than said capillary conduit, but (e) having sufficient capillarity to support ink re ceived therein, and (f) comprising substantially the entire ink storage capacity of said control member, an element disposed between the rearward portion of said transfer surface and said capillary conduit, said element providing with said conduit an air channel communicating with said reservoir and with the atmosphere, a portion of said cells being intersected by said transfer surface to provide communication between said cells and said capillary conduit forwardly of said element, and means intersecting another portion of said cells for venting said cells to the atmosphere, said cells receiving ink through said transfer surface forwardly of said element and dis lacing air through said vent means under conditions of excess ink discharge from said reservoir into said conduit, said cells readily releasing ink to said conduit upon subsequent removal of ink from said conduit whereby said cells remain substantially empty except during said periods of excess ink discharge.

2. The structure according to claim 1, wherein said cells range from about .01 inch to about .07 inch in width.

3. The structure according to claim 1, wherein said element is generally tubular and said transfer surface is generally cylindrical and defined by a bore extending longitudinally through said control member and surrounding said element and said feed forwardly of said element.

4. The structure according to claim 3, wherein said point and said capillary conduit are formed by an elongate generally cylindrical porous element having a multiplicity of pores extending through its outer surface for communication with said generally cylindrical transfer surface forwardly of said tubular element.

5. The structure according to claim 1, wherein said cells are of various sizes, the larger of said spaces comprising storage cells having lower capillarity than said capillary conduit and remaining substantially free of ink except under conditions of excess ink discharge into said conduit from said reservoir, the smaller of said spaces having greater capillarity than said storage cells and providing a vein-like network of capillary passages through which ink is rapidly removed from said conduit and carried throughout said control member to said storage cells under said conditions of excess ink discharge into said conduit from said reservoir, said ink being withdrawn from said cells and returned to said conduit through said network upon subsequent removal of ink from said conduit.

6. The structure according to claim 5, wherein said capillary conduit defines at least one capillary ink channel having a width of about .001 inch to about .005 inch, said cells range from about .01 inch to about .07 inch, and said other spaces range from about .001 inch to about .01 inch.

7. The structure according to claim 6, wherein said matrix is formed of polyethylene.

8. The structure according to claim 6, wherein the void volume of said storage cells comprises between about 40% and about of the total void volume of said fluid control member.

References Cited UNITED STATES PATENTS 1,574,281 2/1926 Doyle. 2,554,654 5/ 1951 Wittnebert. 2,684,052 7/ 1954 Rickmeyer. 2,921,558 1/1960 Von Platen. 2,935,970 5/ 1960 Morse et al. 3,154,055 10/1964 Lawton. 3,340,560 9/ 1967 Nakata. 2,282,840 5/1942 Wing 401-227 2,684,052 7/1954 Rickmeyer 40l199 XR 2,935,970 5/1960 Morse et al 401227 3,340,560 9/1967 Nakata 401198 FOREIGN PATENTS 941,439 11/1963 Great Britain.

1,384,182 1l/1964 France.

ROBERT W. MICHELL, Primary Examiner US. Cl. X.R. 40l-229

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