US2564755A - Writing instrument - Google Patents

Description

Aug. 21, 1951 H. R. FEHLING WRITING INSTRUMENT Filed Dec. 26, 1946 l INVENTOR Hans if 71%11' flTTORNEYS Patented Aug. 21,1951

. WRITING INSTRUMENT Hans R. Fchling, London, England, assignor, by mesne assignments, to Eversharp, Inc., Chicago, 111., a corporation of Delaware Application December 26, 1946, Serial No. 718,336 In Great Britain June 7, 1946 3 Claims. 1

This invention relates to writing instruments and, more particularly, to the type in which a rotatable ball writing member is mounted for rotation in a housing with part of the ball exposed.

In the type of instruments herein indicated, the unexposed part of the ball is housed and in contact with a supply of ink contained in the instrument. As the writing ball member of the instrument is rotated by being moved ove and in contact with a writing surface, a thin film of ink is carried by the ball through the gap between the ball and the housing and this is deposited as a trace on the writing surface. The ink used is preferably a viscous ink of the type disclosed in pending applications Serial Numbers 389,829, now Patent 2,416,145; 657,598, now abandoned; and 659,149, now abandoned, filed April 23, 1941, March 2'7, 1946, and April 2, 1946, respectively.

The housing for the rotatable ball member forms part of the terminal or nib portion of the instrument and is in communication with a source of ink in such writing instrument. It is important that the ball member be well supplied with ink from the instrument without forming any smudges when the instrument is in use and that the size of the gap between the ball and the housing be between 1 10- and 1X10" cms. (1 to microns).

With the above and other features in view, it is an object of the invention to effect improvements in a writing extremity or nib for writing instruments of the type such as are shown and described in co-pending application S. N. 674,262, filed June 4, 1946, now Patent 2,536,924.

As explained in the said patent applications, the size of the gap between the ball and the housing is a critical factor in the efficient operation of the writing instrument. It will, however, be noted that there is a progressive tendency for thegap to widen under prolonged use owing to wear and this widening eventually results in the pen smudging instead of leaving a sharply defined and distinct trace.

Another object of the present invention is to provide an instrument with a fissured ball housing provided with means for feeding ink to the ball member and adapted to compensate for the wear on the housing.

A further object of the present invention is to provide a Writing instrument with a terminal or nib portion having a housing containing a rotatable ball member and forming a gap whose size remains practically constant irrespective of wear.

With the above and other objects in View, the invention will now be described in detail with reference to the accompanying drawings in which Fig. 1 is an elevational view of an embodiment of the invention;

Fig. 2 is a longitudinal, sectional, fragmentary, enlarged view of the terminal or nib portion of an instrument shown in Fig. 1;

Fig. 3 is a cross sectional view taken on line 3; of Fig. 2;

Fig. 4 is a longitudinal, sectional, fragmentary view of a modified form of the embodiment shown in Fig. 1; and

Fig. 5 is alonghudinal, sectional, fragmentary view of another form of the invention.

In the drawings showing exaggerated views, like reference characters refer to like parts throughout. 7

In Fig. 1 is illustrated a writing instrument 1 of the ball point type having a tubular housing 8 and a tapering end portion 9 in the forward end of which is mounted a rotatable writing ball member "I. Said housing contains an ink reservoir such as is described in the co-pending applications previously referred to herein and is adapted to supply ink to the ball member l0.

Referring to Figs. 2 and 3, whichshow the details of construction of the end portion 9, a ball I0 is shown as contained in a housing I2, with its upper portion or lip I4 having spaced diametral slits lb of a capillary size, e. g., of about 0.1 mm. in width, which sub-divide said lip of the housing into separate fingers l8 each serving to enclose the ball [0 as in the jaws of a chuck. It will be noted that said fingers are springy, equispaced and substantially vertically disposed, as shown, and may. extend to the diametric plane of the ball member If). The gap 20 formed between the housing and the ball member is slightly exaggerated, being shown much wider than it actually is. Said fingers I8 have a certain degree of resilienc and, as wear on their interior faces takes place, such as would normally tend to increase the size of the ink filled gap 20, they themselves tend to close and to maintain the gap size substantially constant; e. g., at a preferred value of about 5 microns.

It may here be understood that, although the vertical slits l6, formed in the lip I4, permit ink to flow therethrough, it will be appreciated that, since these slits are of a capillary size, they constitute narrow capillary channels and serve to hold the ink in them in very much the same manner as the narrow gap or slit between the two tongues or points of the ordinary type of 3 pen nib which serves to hold and conduct the extremely fluid ink employed in said type of pens. In effect, it will be noted that the slits provide alternative or supplementary means for conveying ink around the ball rather than facilities for draining the lateral seating and gap by seepage through them to the outside of the nib housing.

This effect is strongly enhanced by making the slits extremely narrow. The desired fine proportions can be achieved by closing-up, for example, by swaging or pressing, the cuts first made by a saw blade of a practical width, in the order of about 0.5 mm. In this manner slits may be produced having a width of no more than 0.01 mm. or 10 microns. This closing in no way detracts from and indeed may enhance the resilient character or chuck action of the fingers IS.

The depths of the slits 16 in the axial or longitudinal direction of the nib may be varied. Since Figs. 2 and 3 illustrate the slits as cut down to the diametral plane of the ball It, the fingers iii are constituted solely by the peined-over part of the lateral seating of the lip I4, it being understood that the ball is retained in its seating b peining the lip thereof. Furthermore, the ball seat 24 is provided in its base 26 with a plurality of grooves 22 extending outwardly of conduit 28. By the presence of grooves 22 between writing member In and the front end of ink passage 28, the writing member is directly exposed to the ink from said passage over an area of the writing member substantially larger than the size of said passage.

In Fig. 4, it will be noted that vertical slits It may be cut down to substantially the full depth of the ball ill in housing [2 thereby imparting a greater length to the fingers l8. The use of slits, as shown in this figure, produces a greater resilience and power of adjustment in the fingers l8 and also renders unnecessary the grooves 22 in ball seat 24 and which, as shown in Fig. 2, are formed in the base 26 of the seating 24 so as to lead outwards from the conduit supply passage 28 from an ink reservoir, not shown, but usually of the type shown in co-pending applications hereinabove referred to.

In Fig. 5 are shown slits l6 extending beyond the depth of ball and which may be made in any usual manner, such as with a circular saw.

The constructions shown in Figs. 4 and have the further advantage that the ball seating area may be larger than any known constructions because the base of the seating may be produced by the application of a punch having a hemispherical end and because the necessity for grooves 22, as shown in Fig. 1, is obviated.

From the foregoing description taken in connection with the drawings, it will be noted that there are two approaches to. a solution of the problem of supplying ink to the writing member without causing smudging after the housing wears down. One is the choice of better materials with better surface finishes thereon, and the second and preferred choice is the compensation for wear by providing means for maintaining the gap substantially constant as wear takes place. It is with this second approach that the present invention is concerned. Compensation for wear of the housing due to use of the ball member therein, however, involves major problems that are mainly due to the small size of the terminal portion of the instrument, known as the nib. Also, the components of said terminal portion of the instrument impose severe manufacturing limitations that will readily be appreciated from 4 the fact that it is desirable to employ a ball of about 1 mm. in diameter.

Furthermore, the writing extremity or nib of an instrument of the type specified, is characterized in that the extreme end or lip portion of the ball housing is split by at least one narrow slit of a capillary size so as to gri the ball resiliently. Within limits, therefore, the resilience thus afforded causes the gap size to remain substantially constant irrespective of wear. It is preferred to provide a plurality of slits at various intervals in the periphery of the lip so that the housing is sub-divided into a plurality of independent resilient and elastic elements which may be referred to as fingers and which, owing to their elasticity, cooperatively grip the ball as in a chuck.

It will be readily observed that, in the production of a terminal writing portion or nib for writing instruments of the rotatable ball point type, the blank nibs are first machined, then one or more vertically disposed slits are formed in the lip section of said nib which are partially closed by means of swaging. The nibs are then drilled in order to .form the conduit 28, said conduit being of about 0.5 mm. in diameter. The seating or base 2% is formed in any suitable mannor by punching or counterboring and then formed into a hemispherical shape by means of a hemispherical punch.

After this sequence is completed, the known operations of inserting the ball into the seating, peining over the lip of the housing, pressing the ball out, and re-inserting it under pressure, are followed. The material of which the nib is made is preferably a high tensile material having a suificiently high elastic limit in order to provide the chuck action without permanent distortion.

While various forms have been described in connection with the accompanying drawings, it will be noted that various changes as to form, use, cooperation and arrangement of materials may be made Without departing from the spirit and scope of the accompanying claims,

I claim:

1. A writing instrument comprising a casing, a terminal portion extending from the casing, and a spherical writing member rotatably housed in the terminal portion adapted to be coated with ink fed from an ink reservoir in the casing, said terminal portion having a, lip constituted by a plurality of springy sections which rotatably retain the writing member and are separated from one another by means of fissures, which fissures are of such minute width as to retain ink therein and prevent the escape of any appreciable quantity of ink laterally therethrough.

2. A writing instrument comprising a casing, a terminal portion extending from the casing, and a spherical writing member rotatably housed in the terminal portion adapted to be coated with ink fed from an ink reservoir in the casing, said terminal portion having a lip constituted by a plurality of springy sections which rotatably retain the writing member and are separated from one another by means of fissures, which fissures are of such minute width as to retain ink therein and prevent the escape of any appreciable quantity of ink laterally therethrough, and said terminal portion including an ink feed passage behind the writing member through which ink is adapted to be fed to the writing member from the reservoir, and said fissures extending about the writing member into communication with said ink feed passage.

.5 k A writing instrument comprising a casing, a terminal portion extending from the casing, and a spherical writing member rotatably housed in the terminal portion adapted to be coated with ink fed from an ink reservoir in the casing, said terminal portion having a lip constituted by a plurality of springy sections Which rotatably retain the writing member and are separated from one another by means of fissures, which fissures are of such minute width as to retain ink therein and prevent the escape of any appreciable quantity of ink laterally therethrough, and said terminal portion including an ink feed passage behind the writing member through which ink is adapted to be fed to the writing member from the reservoir, said terminal portion also including a socket for the writing member which is of spherical shape opposite the sides of the latter and conforms closely to said sides and which is of non-spherical shape behind the writing member at a point between the latter and the front end of said ink feed passage, whereby the writing member is directly exposed to the ink from said passage over an area of the writing member substantially larger than the size of said passage.

. HANS R. FEHLING.

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

UNITED STATES PATENTS Number Name Date 894,488 Enright July 28, 1908 1,387,996 Menger Aug. 16, 1921 2,107,424 Platt Feb. 8, 1938 2,390,636 Biro Dec. 11, 1945 FOREIGN PATENTS Number Country Date 14,103 Great Britain 1895

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