Writing instrument

Aug. 31, 1965

3,203,025

C. SCHREUR

WRITING INSTRUMENT Filed Aug. 15, 1962

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United States Patent Office „ 3,203,025

Patented Aug. 31, 1965

3,203,025 WRITING INSTRUMENT

Clarence Schreur, Escondido, Calif., assignor to Pacific Research Laboratory, Escondido, Calif., a partnership

Filed Aug. 15, 1962, Ser. No. 217,212

Claims. (CI. 15—563)

Ulis invention relates to writing instruments and more particularly to an instrument of the type having a reservoir supply of ink in continuous communication with a stylus or writing nib comprising a very slender flexible bundle of fibers or filaments for feeding ink to the exposed end by capillary action and as needed for leaving a very narrow, thin mark upon the surface contacted, and which capillary feeding core is encapsulated except at its ends by a tubular shroud.

Proposals have been made heretofore to provide handheld marking devices employing a thick-bodied relatively stiff fibrous nib formed of felting, wicking or the like and functioning to feed ink in a wide strip onto the surface being marked and employing the ink-feeding characteristics of felting and wicking. Writing devices of this type are used to advantage in many fields and serve admirably for marking with large or wide symbols, as for example, in the sign painting art and by merchants and artisans when marking rough surfaces as shipping cartons, Inmber, building materials, parcel post packages and the like. Such markers, commonly referred to as fountain brushes, are quite unsuitable for fine work such as that desired for normal writing and accounting purposes requiring sharply defined, narrow, quick-drying lines produced by a nib incapable of flooding as essential characteristics. Felt nibs as heretofore proposed in marking devices have insufficient rigidity and wearing characteristics for practical use as a writing instrument if an attempt is made to slim the nib down to a slender small-diameter contour. The service life is totally unacceptable and the load-supporting characteristics are so small as to require the user to tense the muscles in an attempt to hold the nib lightly contacted with the paper or other writing surface thereby tiring the user after only a very short period of writing. If an attempt is made to sharpen a large cross-section nib of felting to provide a fine writing point, somewhat greater rigidity and supporting capacity is obtained but the sharp point wears away after a brief period of use and there is a pronounced tendency for the sharpened nib to flood as well as to produce a broad line unless the instrument is supported deftly with only the point proper in light contact with the writing surface.

With the foregoing shortcomings and disadvantages of ⁵⁰prior proposals in mind, it is pointed out that it is a prime purpose of the present invention to provide an improved writing instrument retaining certain advantages of fibrous and felt-tipped fountain brush-type marking devices while avoiding many of the limitations, defects ^5aand shortcomings of the fountain brush. Thus there is provided by the present invention a simply constructed, inexpensive, lightweight hand-held writing instrument of the fountain type featuring a generally rigid writing nib comprising an extremely small diameter bundle of closely ⁶⁰compacted filaments, fibers or other equivalent means for feeding ink by capillary action and featuring a thin-walled tubular shroud having numerous functions. Typically the capillary ink-feeding core of the nib may comprise a multiplicity of fine fibers cooperating to provide a large number of very fine capillary passages between their adjacent side walls and having little or no load-supporting capability by themselves, the latter important and essential requirement being performed by the encapsulating or surrounding shroud of thin-walled flexible material. For ‘° example, this shroud may comprise a suitable plastic immune to attack by the constituents of the ink and having wealing qualities greatly enhancing the wearing properties of the capillary core material. Only the opposite ends of this core are left uncovered, the inner ends being in intimate contact with the ink supply and the outer ends being exposed just sufficiently to convey the ink into contact with the surface being written upon. The end of the shroud is rounded to form a continuation of the wearrounded exposed outer end of the core.

In normal usage the nib is held at an angle inclined to the surface being written upon with the result that the lowermost edge of the nib shroud forms a glide surface firmly and accurately supporting the writing force applied to the instrument and effective in holding the adjacent end. portion of the capillary material in contact with the surface to apply ink thereto.

. Accordingly, it is a primary object of the present invention to provide an improved writing instrument featuring a novel mb and capable of making a fine line imprint of predetermined width on a wide range of surfaces and irrespective of whether these surfaces are rough, porous smooth, glossy, etc. ’ . Another object of the invention is the provision Of an inexpensive hand-held writing instrument having an elongated very small diameter nib featuring a capillary core encapsulated in a protective generally rigid shroud for the core, adding support and rigidity thereto and assuming a major portion of the wear-resisting characteristics of the nib assembly.

Another object of the invention is the provision of a writing instrument having a small diameter tubular nib mounted, within the lower end thereof and designed to bear against the writing surface and to cooperate with a core filling in forming a multiplicity of capillary inkfeeding channels.

. Another object of the invention is the provision of a nib for a writing instrument comprising a thin-walled tubular housing charged throughout its length with capillary ink-feeding means effective to supply ink as needed to the surface-contacting end of the nib.

Another object of the invention is to provide an inkfeeding nib comprising a seamless abrasion resistant plastic tube charged with fibrous material exposed at the opposite ends of the tube and forming a multiplicity of capillary ink-feeding channels.

These and other more specific objects will appear upon reading the following specification and claims and upon considering in connection therewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of the invention is illustrated—

FIGURE 1 is an elevational view partly in section of a writing instrument incorporating the present invention;

FIGURE 2 is a fragmentary cross-sectional view on an enlarged scale taken through the nib-supporting portion of the instrument;

FIGURE 3 is a fragmentary cross-sectional view on an enlarged scale taken along line 3—3 on FIGURE 2; and

FIGURE 4. is an enlarged fragmentary sectional view taken lengthwise of the writing instrument at the junction of the nib with the main body, as is indicated bv the line 4—4 on FIGURE 2.

Referring more particularly to FIGURE 1, there is shown one preferred embodiment of a writing instrument designated generally 10 embodying the features of the present invention. This instrument includes a tubular main body 11 of any suitable material such as molded plastic.. Main body 11 has a tapering lower end 12 formed in its axial.tip with a noncircular opening 13 supporting therein a nib 14. When not in use, nib 14 is preferably guarded by a protective cap 15 having a friction

3,203,025 ⁴maintained in very light contact with the surface, and this is true irrespective of the direction from the vertical to which the pen is inclined when starting to write.

Shroud 2® is the main component resisting wear of the 5 nib. If selected from a material having a small coefficient of friction, as is desired, the shroud is found to be extremely long wearing and highly effective in protecting and prolonging the service life of core filling 21..

Another feature of the invention is best shown in ₁₀ FIGURES 2 and 3 and has reference to the mounting of nib 14 in main body 11. Preferably mounting opening 13 is noncircular in cross-section, such as of the hexagonal shape shown in FIGURE 3. The smaller diameter of this hexagonal opening is somewhat less than 15 the exterior diameter of shroud 20 with the result that the shroud has a snug frictional fit within the opening yet leaves a plurality of voids or very small openings 24 serving as air vents to admit air as the ink supply is consumed during use of the instrument. The air vents also 20 accommodate temperature and pressure changes without permitting leakage of the ink supply. Should nib 14 become damaged or unusable for any reason, it can be easily withdrawn and replaced by an identical replacement nib.

The mode of operation of the described writing instrument will be quite apparent from the foregoing detailed description of its components and their operative relationship to one another. As will be readily apparent, the tip of nib 14 may be applied to the surface to be written 30 upon with any portion of glide surface 23 in contact with the writing surface and serving as a glide shoe. Varying writing pressures are absorbed substantially entirely by shroud 20 with but slight or imperceptible flexure of the nib body. Small scale repeated flexure of the nib trans35 versely of its length does occur in normal writing but in an amount so small as to be well within the elastic limit of the nib assembly. Irrespective of this repeated flexure, the nib will instantly return to its original straight condition as the pressure is relieved and this is true even though 40 extreme deflection of the nib occurs through accident or other cause.

Desirably absorbent material 17 is charged with an ink formulation which feeds readily by capillary action and which dries rapidly even on nonporous substrates such as ₄5 glass, metal, plastics and the like nonporous surfaces, and which resists removal by a wide range of solvents. A suitable ink meeting these requirements consists of 10% ester gum, 5% oil soluble dye, and 85% toluene. _ Numerous other ink compositions having generally similar 50 characteristics to those just mentioned and known to the art may also be used.

While the particular writing instrument herein shown and disclosed in detail is fully capable of attaining the objects and providing the advantages hereinbefore stated, 55 it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as defined in the appended claims.