US2536124A - Writing instrument - Google Patents

Description

Patented Jan. 2, .1951

WRITING INSTRUMENT Camille Mariano Franois Bolvin and Marius Jean Lavet, Paris, France Application February 28, 1948, Serial No. 11,936 In France October 11, 1946 3 Claims. l y

The present invention relates to conventionala fountain pens comprising instead of the conven tional pen a small rotating tracing ball which is automatically coated with a highly viscous ink contained in an ink-reservoir of large capacity, the said ink being supplied in very small and yet sufcient quantities to give immediately tracings which dry instantaneously.

In a fountain pen of this kind, the following conditions must be fulfilled.

1. During writing, the ball must always roll to draw out a layer of ink on its periphery and toA convey the ink in this manner to the paper. Consequently, the seat against which the ball bears must be able to withstand the wear and dirt.

2. Ink must be supplied in very small and y et suicient quantities to trace uninterrupted and evenly fed lines, the pen being held inclined and the direction of the displacements of the ball on the paper being very variable.

3. The duct which supplies the ink from the ink-reservoir to the ball should never be clogged by dried ink in the passage vents, either through an excessive increase in viscousness or through the introduction of dust, paper particles, metallic dust due to the wear of the rubbing parts, etc.

4. When the ball fountain pen does not work anymore after a mishap or an unforeseen exhaustion of the ink-reservoir, the user of the pen i should be able to t up easily and rapidly a new emergency writing device ready for service.

5. Finally the mass production of the fountain pen must not be subject to excessive difficulties and must not lead to high cost prices. larly a strict observation of the allowance for the plays between assembled parts must be easy; as those parts are very small, delicate machining should be avoided such as drilling very small diameter over long lengths, very ne threading, accurate settings requiring highly skilled labor, etc.

It will be noted that all these conditions complement one another and are indispensable for reaching the nal and desired result. Now, it is a fact that this ensemble of qualities is not obtained with the various designs which are put forward up to the present. Particularly the metallic surfaces upon which the ball is resting while it slides are rapidly worn out in the types of scribers which are used at present; the setting operation required to hold the ball in its recess with an exceedingly small play is made by hand under irregular and very often faulty conditions.

Particu- It is found that the ball has a tendency (Cl. 1Z0-42.4)

to be blocked intermittently in a xed position; thelines which are obtained are often punctuated and their variable irregularities depend at the same time upon the direction of the displacement of theA fountain pen and its inclination with respect to paper. When irregularities of lines are taking place the user has the tendency of pressing the scriber strongly on the paper which subjects the parts that guide ther ball to comparatively considerable thrusts. Defects are then increasing rapidly and theball is finally jammed to rest; accordingly ink is no more supplied and the pen is out of service. The recess of the ball being deteriorated, repair is practically impossible.

The design of a good scriber according to the old processes shows great difficulties, for the diameter of the ball is very small (one mm. approximately) and the shape of the tiny recess for the ball must be obtained by removing matter with extraordinarily reduced manufacturing margins. In order to provide the vents and grooves required for the passage of the ink, the part upon which the bail is resting has been reduced to a small surface. Accordingly when one presses down strongly on paper, the pressures per unit surface reach extremely high values which exceed the utlimate strength of the metals which are ordinarily used for the manufacture of the conventional types of pens. The result is either that they wear out extremely rapidly on account of the slide friction or that they undergo permanent deformation which modify the value of the play and lead to the clogging of the vents which supply the ink.

The object of the present invention is to provide an improved fountain pen which does not show the serious inconveniences mentioned above.

This fountain pen is remarkable particularly in that thev tracing ball is resting upon a seat constituted by the concave highly polished and nearlyvcovering area of a hard piece which has been selected so that the friction coefficient of the ball covered with ink with respect to its seat remains always smaller than the friction coeilcient of the ball covered with ink with respect to the paper or to any other surface receiving the inscriptions.

The piece forming the seat is preferably constituted by a natural or synthetic stone of the group of stones (ruby, synthetic sapphire, etc.)

used for the manufacture of pivots and counter-- will become apparent from the course of the following description, when read in conjunction with the accompanying drawing showing, by way of example, a preferred embodiment of the invention.

In the drawings:

Fig. 1 is an enlarged longitudinal section of the front part of an improved fountain pen according to the invention seen in the position in which it is usually held;

Fig. 2 is a transverse section of Figure 1 along line II--II showing the ducts bringing the viscous ink to the ball:

Fig. 3 is a detail and much enlarged longitudinal section of the housing of the ball;

Fig. 4 ls a much enlarged perspective view of the piece constituting the seat on which rests the ball and of the inner support of the said seat;

Fig. 5 is a top view of a seat for a ball, the said seat being drilled and grooved;

Fig. 6 is a section of Figure 5 along line VI-VI.

According to the illustrated form of embodiment shown on Figs. 1 to 4, the front part of an improved fountain pen according to the invention comprises a ball I fitted in a widely opened housing; the-bottom of the said housing constitutes a bearing surface for the ball; its general shape is that of a concave spherical segment whose radius is substantially equal to that of the ball. The radius of the said bearing surface is preferably slightly larger than the radius of the spherical ball to provide a large surface of contact between ball and seat. and the spherical segment constituting the bearing surface of the ball extends over an angle a of about 120 (see Fig. 3).

'I'he ball is guided sideways by a cylindrical wall having an inner diameter slightly larger than the diameter of the ball. The said wall is integral with a sheath 2 having the form of a truncated cone the open end of which has a thin circular lip 3, 3 out of which a portion of the ball projects. The rim of said lip converges slightly towards the ball I and its diameter is slightly smaller than the diameter of the ball. The difference between those two diameters is of the order of one hundredth of a millimeter. The side and longitudinal play of the ball is very small (smaller than three hundredths of a milli meter). As shown on Figs. 1 and 3, the ball is uncovered over a surface which is very close to that of half a sphere and which permits writing when the fountain pen is held inclined with respect to the paper.

Behind lip 3, 3 there is provided an annular recess 4, 4' which is intended to be filled with a very viscous and semi-fluid ink fed through several channels distributed around ball I.

The spherical concave surface against which the ball is pressed when writing and the side wall 1 of the recess containing the ball are formed respectively on two concentric pieces. namely, a seat for the ball, and the end of sheath 2.

According to the present invention, the spherical surface of the seat 5 upon which slides the rotating ball is extremely hard and perfectly polished while the taper end of the sheath belongs to a piece made from a ductile and elastic metal such as drawn brass, stainless'steel,` nickel. nickel silver, beryllium bronze, etc. This metal must not be attacked chemically by the ink used. According to a preferred embodiment of the I natural stone or a synthetic stone such as invention the seat 5 of ball I-is constituted by corundum. ruby, sapphire, etc. The piece 5 may be cut and shaped by grinding; it may also be obtained from a stone powder agglomerated by a binding material and moulded according to an art which is well known.

The seat of the ball is shown separately on Figures 5 and 6 in which it may be seen ythat it has the form of a small cylinder whose diameter is very close to that of the ball. The face that rests on the ball has the shape of a spherical segment whose radius is very close to or slightly larger than that of the ball. Thus for instance, the radius of the concave surface may be of about 0.52 mm. if that of the ball is of about 0.5 mm.

The seat 5 ls preferably drilled with a small/ hole 5I. In the concave suriace,'three arcuate divergent grooves 6, 6i and 6" are cut (Fig. 5). The said 'grooves which are like scratches are narrow and open on the center hole. They may be obtained by grinding or etching, for instance by means of a small and thin disc rotating very rapidly, the said disc being coated with diamond powder contained in a liquid. The said grooves may also be obtained by moulding when the pieces 5 are obtained agglomerating fine powder of a very hard material.

The spherical .surface resting on the ball must be comparatively large with respect to the area obtained in cutting off the grooves 6, B' and 6".

The seat 5 is inserted and stuck at the end of a hollow tube 1. The said tube is elongated and arranged coaxially with the pen. A perspective view thereof is shown in Fig. 4. Its truncated front end is tapered in the neighborhoodV of the seat of the ball. The tube 'I fits into sheath 2 the shape of which is shown by the longitudinal section given in Fig. l. It can be seenthat the sheath is provided intermediate its ends, substantially at its middle part. with a truncated annular shoulder 8'. 8". Its end remote from theball, shows a tubular, slightly tapered portion 9 over which is engaged by friction a long tube Il constituting the ink-reservoir.

The inner tube 'I is constituted by a ductile and stainless metal, easy to machine, such as brass or nickel silver. It is inserted with a tight frictional flt in the sheath 2 and is adjusted therein, to determine with a high accuracy the axial play of the ball I.

Before mounting the seat 5 in the tube 1, three uniformly distributed slits II, Il and II" are milled in the wall of the said tube, as shown in Figures 2 and 4. As shown in Fig. 1, these slits Il make the ink-reservoir I0 communicate with the annular caviety 4.

The tube 1 is partially slit on its front part and4 is surrounded by sheath 2; owing to this arrangement, three channels are provided which are parallel to the axis of the pen and intended to supply the ink around the ball on an equatorial line adjacent to lip 3, 3'.

After numerous comparative tests, it has been found that the performance of the Writing instrument described above is far better than that of similar instruments known hitherto, and that this superiority is confirmed as being particularly important when the condition of the surface of the ball is appropriately chosen together with the physical and chemical properties of the ink.

Thus, it is of advantage to have the ball made from a ,material which is less hard than the material from which the seat 5 is made in order to avoid scratching by the Aball of the concave surface of the seat 5. It is also of advantage to have the outer surface of the ball slightly unpolished and strewn with pores. However the asperities on this surface must be very fine and the tops of the grains thus formed must be invisible with the magnifying glass. The spacing between these asperities vand the depth of the pores should be less than one micron, or, in other words, lessl than one thousandth of a. millimeter. This porous surface should be perfectly wetted by the ink, that is to say the ink should be drawn within the pores on the ball surface and adhere strongly to them in order to penetrate into the ne cavities without having the tendency of moving sideways with respect to the said cavities.

The hardness of the tops of these asperities I should be high but however slightly lower than that of seat 5. The material with which the ball is made should withstand properly wear by friction. The inner body of the ball should be highly elastic and the asperities should not be canted olf rapidly and disappear during the sliding motion of the ball on its seat.

It is also necessary that the friction of the ball v on its seat does not cause the well known mishap known as "jamming.

Particularly good results have been obtained by adopting a seat made of hard sapphire and a ball made of agate, the said agate being of the quality known yas calcedonic agate; certain quartzes have also given good results, Metallic balls may also be used; the metals to be preferred are tempered steel, nickel steel and chrome nickel steel, beryllium bronze hardened by thermal treatment, chromed nickel steel.

In all cases it is necessary to remove the polish of the ball surface in a particular manner in order to obtain an appropriate porosity. This removal may be obtained by making the balls roll between two plates made of a soft material between which a liquid is introduced, the said liquid containing some very fine diamond powder. The size of the diamond grains should be less than one micron. The said grains should incrust strongly in the plates and the latter should be provided with a very complex motion so as to make the balls roll in every direction and receive some line incrustations, the diamond powder however adhering mostly to the plates which are used for removing the polish and not so much to the balls. The liquid containing the diamond powder in suspension may be oil or water. After the removal of the polish, the balls must be cleaned and their sphericity must be properly checked.

For mass productiom each category of balls characterized by very close diameter values are associated with sheaths machined in such a way that the diameter of the lips diiers from that of the balls by a well determined value which is supplied by tests on specimens. In this manner the rejection of balls is very much reduced.

It is evident that the above results require a most careful manufacture as the plays between the constitutive parts are very small and must be observed carefully with allowances less than one hundredth of a millimeter. A process of manufacture is indicated further which permits to meet this condition easily.

To appreciate the importance and novelty of writing instrument according to theinventlon its behaviour will now be analyzed. Fig. 3 shows the behavior of the elements of the pen when being inclined over the sheet of paper it is moved in the direction f1. Owing to Newton's principle of the equality of action and reaction, the ball presses at the same time on the sheet of paper and on the seat 5 and the pressure P is the same.

When the ball slides on seat 5, so that a frictional force F is developed which is: F1==K1P. K1 denoting the friction coeflicient for the ball coated with ink with respect to seat 5 which is also coated with ink.

Should the ball be pressed on the sheet of paper with the same pressure P without making it roll on its seat, the frictional force developed would be: F2=K2P, Kz denoting the friction coeicient of the ball coated with ink with respect to paper.

The rotation of the ball depends upon the difference between the torques F1 and F2, that is the products of the forces by their lever arm; but these lever arms are the same since they are equal to the radius of the spherical ball.

For making the ball rotate with respect to seat 5, K1 therefore must be smaller than K2. In other words it is indispensable for the ball coated with ink to slide most easily on the bearing surface ofthe seat 5 and to adhere strongly t0 paper. This behavior depends at the same time on the surface conditions of the solid constitutive elements and on the qualities of the viscous ink used. That ink must constitute a lubricant for the polished seat of the ball and 0n the other hand it must hinder sliding on the paper in order to cause the required rotary motion for distributing the ink. The properties of the ink with respect to the ball and to the fibrous paper must therefore be those of a glue. Experience has shown that the choice of the materials mentioned above is satisfactory. Furthermore good operation lasts for a very long period for all precautions have been taken for reducing the wear and alteration of the materials.

Another important advantage of the embodiment shown on Fig. 1 resides in that it allows to obtain removable and easily repairable ball fountain pens. In fact, since the recess holding the ball consists of two concentric elements, means may be provided to separate these two pieces. Under those conditions the ball may be easily removed and replaced; the openings for the passage of the ink may also be easily cleaned; nally the seat of the ball may be repolished. In the embodiment shown in Figure 1, the elements such as l, 9 and I0 are tubular and may be easily mounted into each other with a slight friction. Said elements may also be tted into one another rather tightly and made integral by means of a screw; they may be joined by soldering and then separated by heating or may be stuck together by means of a product which can be dissolved by plunging them in an appropriate solvent, etc.

While the arrangement herein shown and described is admirably adapted to full the objects primarily stated, it is to be understood that it is not intended to conne the invention to the form or embodiment herein disclosed for it is susceptible of embodiment in various forms all coming within the scope of the claims which follow.

What we claim is:

1. In a ball pointed fountain pen, in combination a substantially cylindrical ink reservoir, a rst cylindrical sleeve slidably engaged in the front part of said reservoir and having a'beveled front end ending in an annular rim, a second cylindrical sleeve, slidably engaged in the rst one, having its front part beveled and recessed,

1 and engaged in spaced relationship within the beveled part of the rst of said sleeves to form therewith an annular chamber, a seat engaged in said recess, having a central hole substantially coaxial with the ink reservoir and a spherical surface the center of which is between the said seat and the annular rim, substantially in the neighbourhood of the latter, a ball rotatably lodged between the seat and the annular rim and having a diameter slightly less than the diameter of the spherical surface of the seat, and apertures in the sidewall of the second cylindrical sleeve for establishing a communication be- -tween the ink reservoir and the said chamber.

2. A ball pointed fountain pen according to claim 1, wherein lthe spherical surface of the seat is provided with arcuate divergent grooves communicating with the center hole in said seat.

3. A ball pointed fountain pen according to claim 1 in which the apertures in the said second sleeve are formed by three longitudinal slits milled at 120 on the side face of said sleeve.

CAMILLE MARIANO FRANCOIS BOLVIN.

MARI'US JEAN LAVET.

assenza .1 .A 3 REFERENCES cri-En The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 451,808 Cooper May 5, 1891 1,020,221 Rauchenecker Mar, 12, 1912 1,391,267 Nelson Sept. 20, 1921 1,808,489 Bassi June 2, 1931 1,938,835 Grzyb Dec. 12, 1935 2,021,141 Boyer Nov. 19, 1935 2,199,265 Lobry Apr. 30, 1940 2,328,580 P ickus Sept. 7, 1943 2,390,636 Biro Dec. 11, 1945 2,416,145 Biro Feb. 18, 1947 2,432,061 Chesler Dec. 2, 1947 2,449,939 Heyberger Sept. 21, 1948 FOREIGN PATENTS Number Country Date 2,939 Great Britain of 1911 800,851 France of 1936 772,173 France of 1934

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