EP0326716B1 - Drawing implement comprising a writing nib whose front part determines the width of the drawn line - Google Patents

Abstract

The drawing implement (8), in particular for numerically controlled drawing systems, has a writing nib (1), whose front part (3) determines the width of the line of the drawing implement (8), and a supply of writing medium to the writing nib (1). The drawing implement (8) is distinguished by provision of a rotatable rolling body which serves as spacer and projects over the front part (3) of the writing nib (1) and by the projection of the rolling body being dimensioned in such a way that a capillary gap for the writing medium is formed between the front part (3) of the writing nib (1) and a writing or drawing bearer resting against the projection end of the rolling body. The drawing implement (8) requires comparatively little production outlay. Using the drawing implement (8) even, standardised and sharp lines can be drawn even on difficult and abrasive writing or drawing bearers, the front part (3) of the writing nib (1) hardly being subjected to wear. <IMAGE>

Description

The invention relates to a drawing device, in particular for numerically controlled drawing systems, with a drawing end, the end face of which determines the drawn line width of the drawing device and, when in use, has a capillary gap between itself and a writing or drawing medium, with a supply of writing medium to the drawing end and with one Rotating rolling element protruding from the end face of the character end.

Such a drawing device is known from GB-A-531 940. At the end of the drawing, a ball is embedded as a rolling element, which is pressed directly or indirectly by pressure springs from the inside against a ball seat and can release this ball seat for the flow of ink by pressing on the writing instrument. Thus, the distance between the end face of the end of the drawing and a writing or drawing medium can have an alternating difference.

This document shows different solutions either only with a rolling element and in contrast only slightly laterally projecting end face or with a relatively large end face for a larger line width, in which several ink outlet openings are provided to the To be able to wet the end face sufficiently with ink, so that a correspondingly large number of sealing balls are necessary as valve parts. Such a device is complex and prone to failure and, above all, there is a risk that either too much or too little ink will be dispensed. In particular, the balls can wear out after a certain time, so that their closing action can also be impaired.

Signs of a different kind are considerably less complex, which have a drawing tip designed as a tube. The end face advantageously determines the width of the line drawn, so that uniform, standard-compliant and sharp lines or "lines" can be produced. If such drawing devices are used on a large scale and at high working speed, for example in numerically controlled drawing systems, so-called plotters, high-quality materials must be used in order to achieve a sufficiently long service life. Abrasive writing or drawing media in particular, for example matt drawing foils, result in high wear on the end face of the drawing device. So far, drawing devices of this type have therefore often only been used in a one-way system and / or the end of the sign has been provided with a hard metal insert, for example. The associated design effort and the use of high-quality materials have so far in turn led to very high production costs even if the drawing device is only intended for one-time use.

It is therefore the task of creating a drawing device of the type mentioned at the outset, the production of which involves comparatively little effort and which is hardly subject to wear on abrasive writing and drawing media, but which nevertheless enables uniform, standardized and sharp-edged lines.

The solution according to the invention provides that the protrusion of the rolling element in a drawing device of the type mentioned in the introduction is dimensioned such that the capillary gap for the writing medium is formed between the writing or drawing support resting on the protruding end of the rolling body and the end face of the drawing end, the end face having grooves running from the inside to the outside with capillary cross-sectional dimensions.

The rotatable rolling element thus does not serve as part of a valve which must be mounted against spring force and must also be flexible in order to allow the writing fluid to escape to the end face. Rather, it has the task of preventing the end face of the end of the sign, which is used exclusively for applying the ink or writing fluid, from rubbing and being worn on the paper, the film or the like. At the same time, this ensures a constant, standard-compliant line width, even after prolonged use and heavy use of the drawing device. It is possible to dispense with the use of resistant and expensive materials at the end of the drawing and its end face, which reduces the manufacturing outlay as well as the avoidance of springs pressing the rolling elements against a locking seat. The protrusion caused by the rolling element is very small and is expediently only a fraction of a millimeter, so that the capillary gap already mentioned is formed between the end face and the writing or drawing medium. This makes it possible to apply even, sharp-edged lines to difficult writing surfaces such as foils without disruptive interruptions.

The rotatability of the rolling element not only reduces the wear on this part which maintains the distance of the capillary gap, but rather also enables the drawing device to be easily guided over the writing or drawing medium when writing or drawing. Advantageously, a single outlet for writing liquid is sufficient, because it runs through the grooves running from the inside to the outside with capillary cross-sectional dimensions is quickly pulled outwards onto the surface of the end face, which is advantageous for a certain width of the line to be produced.

It is particularly advantageous if the rolling element is designed as a ball and is preferably arranged centrally in the end face. A rolling element designed as a ball only touches the writing or drawing surface in a punctiform manner and thus forms a largely continuous capillary gap in the area of the entire end surface of the drawing device. In addition, a rotatable ball allows the drawing device to be moved easily and freely in any direction on the writing or drawing medium. The central arrangement of the ball makes it easier to move the drawing device when writing or drawing with a capillary gap practically constant on each side of the end face and not to use it at an excessive angle.

When viewed superficially, the drawing device according to the invention with a rolling element designed as a ball has a certain similarity to conventional ballpoint pens. However, it differs significantly from these in its structure and mode of operation. While ballpoint pens usually encircle the writing ball with its outer flanged edge just below the great circle, in the drawing device according to the invention the ball protrudes only a fraction of a millimeter. The line width is determined by the face of the end of the character and not by the size of the writing ball and the possibly lower pressure force on this ball. While with a ballpoint pen a pasty writing medium is constantly transferred to a surface with the help of the writing ball, the capillary gap is essential for the writing function of the drawing device according to the invention.

Due to its capillary action, it sucks the writing medium into the area between the end face and the drawing medium and, unlike previously known ballpoint pens, allows the drawing device according to the invention to be used to write or draw well and reliably on difficult writing or drawing media such as foils.

Ballpoint pens and marking pens are also known, the writing ball of which is spring-loaded in the ballpoint pen tip and is arranged to be displaceable in the direction of the ballpoint pen axis. Such pens or marker pens are described for example in DE-AS 12 09 912, DE-OS 25 59 158, US-PS 15 63 408 and FR-PS 950 038. They are intended to produce a variable stroke width depending on the pressure exerted on the writing ball, but they all also start from the basic principle of a conventional ballpoint pen, in which the expulsion and application of the writing medium to a writing surface is primarily due to the fact that ink, for example, is entrained by the writing ball - Rotation takes place. In the case of these known ballpoint pens or marking pens, the writing medium is at most brought to the writing ball by capillary forces, but not also to the writing or drawing medium. If, in such previously known devices, the writing ball is designed to be movable in the direction of the ballpoint pen axis, the flanged edge surrounding it can possibly be brought up to a slight distance from the writing surface. However, the flanged edge is not designed such that - as in the drawing device according to the invention - a capillary gap would form between an end face which determines the line width and the writing surface. In the case of the ballpoint pens and marking pens mentioned, the arrangement of the writing ball which is displaceable in the direction of the ballpoint pen axis already stands in the way of this.

In the drawing device according to the invention, it is advantageous if the ball consists of metal or hard metal. A metal ball, in particular if it is rotatable, it is practically not subject to wear.

A simple feeding of the writing medium to the end of the sign can consist in that the ball is supported in the end of the sign with a play that preferably forms capillary forces and is supported on the back in the area of the end of the sign opposite the end face by at least two holder-resistant, preferably web-shaped abutments, which the ball along a Touch small circle or point-like with their appropriately beveled contact surfaces.

The writing medium initially flows down from its reservoir into the area of the abutment. Since these are web-shaped, the writing medium can flow past them up to the upper area of the ball. Since the ball itself is supported with play, the writing medium can then continue to run between the ball and the end of the character that surrounds it up to the end face. The play of the ball in the end of the drawing is expediently chosen to be so small that capillary forces also promote the flow of the writing medium up to the edge of the end face. The abutments support the ball upwards and guarantee a constant capillary gap between the end face of the end of the sign and the writing or drawing support due to its holder-resistant design. At the same time, they secure the position of the ball in the direction of the longitudinal axis of the drawing device. During the writing and drawing process, the ball in the drawing tip practically rubs only on the contact surfaces of the abutments; this creates a smooth line drawing. With the help of the bevelled contact surfaces, the ball can be automatically centered in the longitudinal axis of the writing instrument during the writing process. In addition, bevelled contact surfaces - in contrast to the contour of the sphere - reduce the direct contact area between the latter and the sphere and correspondingly reduce the frictional forces arising there.

It is conceivable to design both the drawing end and the ball from metal. However, the manufacturing effort is reduced and the stability of the drawing device according to the invention is increased if at least the region of the drawing end surrounding the ball is made of preferably elastically expandable plastic. In particular at the high writing and drawing speeds achieved by plotters, the ball of the drawing device used rotates at very high speeds in the end of the drawing. If both the ball and the surrounding area of the drawing end are made of metal, there is basically the risk that the surfaces of the ball and the drawing end rubbing against each other will tend to "eat" as a result of the frictional heat that occurs and the drawing device will thus become unusable. This is avoided if the end of the sign is at least partially made of plastic. In this case, elastically expandable plastic reduces the manufacturing outlay because the ball can simply be snapped into its mounting in the end of the drawing when the drawing device according to the invention is manufactured. Even with abrasive writing or drawing media, the use of plastic as the material for the end of the sign does not have a disadvantage, since the ball serves as a spacer and the end face of the end of the sign itself does not come into contact with these media, or just does so.

When using elastically expandable plastic, the end of the drawing can also be in one piece and can be produced, for example, as a molded part. Only in the case of smaller line widths and correspondingly fine spheres is it expedient if the end of the drawing is of multiple parts and is preferably composed of two parts which can be plugged together and are rotationally symmetrical at their plug-in areas.

It is advantageous if a writing medium reservoir filled with ink or ink is provided in the drawing device.

Both writing media serve simultaneously as lubricants for the ball that is stored in the end of the sign and rotates during the writing and drawing process.

Fig. 1

das teilweise abgebildete Zeichenende eines Zeichengerätes in Schnittdarstellung,

Fig. 2

ein erfindungsgemäßes Zeichengerät in einer seitlichen Teil-Schnittdarstellung,

Fig. 3

ein mehrteilig ausgebildetes Zeichenende in einer seitlichen Teil-Schnittdarstellung und

Fig. 4

ein Zeichenende, dessen Stirnfläche kapillar wirkende radiale Rillen aufweist, in einer Aufsicht (Fig.4a) und einer seitlichen Teil-Schnittdarstellung (Fig.4b).

The invention is explained in more detail below on the basis of advantageous exemplary embodiments in conjunction with the drawings. Show it:

Fig. 1

the partially shown character end of a drawing device in a sectional view,

Fig. 2

a drawing device according to the invention in a partial side sectional view,

Fig. 3

a multi-part character end in a partial side sectional view and

Fig. 4

a drawing end, the end face of which has capillary-acting radial grooves, in a top view (FIG. 4 a) and a partial side sectional view (FIG. 4 b).

1 shows the lower region of a character end, designated 1, of a writing and drawing device according to the invention. In the character end 1, a ball 2 serving as a spacer is rotatably mounted. It keeps an end face 3 of the character end 1 at a distance from a writing or drawing support 4 such that a capillary gap K can form between the writing or drawing support 4 and the end face 3. The ball 2 is supported in the drawing tip 1 with play and is supported on the back by web-shaped abutments 5 which touch the ball with its beveled contact surfaces 6 along a small circle. The Abutments 5 are arranged in a writing medium channel 7. The writing medium - for example ink or ink - flows down in the writing medium channel 7 past the abutments 5 to the ball 2. The lateral play of the ball 2 in the end of the drawing 1 allows the writing means to continue past the ball 2 to the end face 3. The game between the ball 2 and the area of the character end 1 encompassing it is selected such that capillary forces also promote the flow of the writing medium towards the end face 3. The writing means serves as a lubricant for the ball 2 rubbing during the writing or drawing process, particularly on the contact surfaces 6 of the abutment 5. While the ball 2 is made of metal, the drawing tip 1 in FIG. 1 consists essentially of solid plastic.

The line width of the drawing device is not determined by the ball 2, as in the case of a ballpoint pen, but rather by the end face 3 of the drawing tip 1. With a corresponding design of the end face 3, uniform, standard-compliant and sharp-edged lines can be drawn with the drawing device according to the invention. The end face width B is exactly limited and can be adjusted to the desired line width. The drawing device can also be used to write or draw on difficult writing or drawing media 4 - for example on foils - well and without disruptive interruptions. This is made possible by the capillary gap K between the end face 3 and the writing or drawing support 4, which is kept constant by means of the ball 2 supported on the back by the abutment 5. Even with prolonged use of the drawing device according to the invention, its line width remains constant since the end face 3 practically does not come into contact with the writing or drawing support 4 and is therefore hardly subject to wear, even with abrasive media, such as matt foils. Usually, the rotatable ball 2 alone rolls over the writing or drawing support 4. Grooves 13 that extend outwards are omitted for better clarity in FIG. 1, and also in FIGS. 2 and 3, and are explained with reference to FIGS. 4a and 4b.

Fig. 2 shows the drawing device 8 in a partial side sectional view. A fibrous writing medium conductor 9 can be clearly seen. This leads ink or ink from a larger writing medium reservoir 10 behind it to the end of the character 1. The writing medium reservoir 10 can likewise consist of a fibrous material or can also be designed as an ink cartridge.

2 also shows the beveled contact surfaces 6 of the abutments 5, which touch the ball 2 along a small circle; during the writing process, they automatically center the ball 2 in the longitudinal axis of the drawing device 8.

The drawing device according to the invention can be used both for numerically controlled drawing systems and with the aid of a manual guide part for manual drawing. With a corresponding design, the drawing device can also be used, for example, to produce technical drawings by hand, mark stencils or write letters. Its design with a capillary gap and a rotatable ball serving as a spacer also allows use on difficult or abrasive writing or drawing media. Nevertheless, the manufacture of the drawing device according to the invention is possible with comparatively little effort.

Fig. 3 shows a two-part character end 1 ', which is composed essentially of a lower and upper parts 11a and 11b. The parts 11a and 11b are pressed together at their rotationally symmetrical plug regions 12a and 12b during the manufacturing process of the character end 1 'and hold the ball 2 between them in their interior. Such a design of the character tip 1 'is particularly useful for fine balls, because a one-piece character tip could be difficult to form so that even a very fine ball can be snapped into it.

4 shows, at the end of the drawing 1 ″, other end face 3 ′, radial grooves 13 which run from the inside to the outside, as are also provided in the examples described above. 4a shows the radial arrangement of these grooves 13 on the end face 3 ', which is associated with comparatively little manufacturing effort and is therefore preferred, and FIG. 4b shows their arrangement and design in a lateral partial sectional view. These grooves 13 are dimensioned so narrow in their cross-sectional dimensions, especially in their width, that they also act capillary. In this way, they draw the ink or ink faster outwards onto the surface of the end face 3 ', which is particularly advantageous when the tips of the characters are wider.
Fig. 4 shows a possible embodiment; the grooves 13 could, however, also be designed, for example, to be open toward the outer edge or just to extend to the outer and / or inner edge of the end face 3 '. In these possible embodiments, too, the grooves 13 support the distribution of the ink or ink, which is sufficiently drawn in by the capillary gap K shown in FIG. 1, on the end face 3 or 3 'of the various exemplary embodiments.

Claims (9)

1. A drawing implement, particularly for numerically controlled draughting systems, comprising a drawing end (1, 1', 1'') whose front part or face (3, 3') determines the width of the line drawn by the drawing implement and in use has between itself and a graphic carrier (4) a capillary gap (K), comprising a means feeding writing medium to the drawing end (1, 1', 1'') and further comprising a rotatable rolling element projecting beyond the face (3, 3') of the drawing end (1, 1', 1''), wherein the projection of the rolling element is dimensioned such that the capillary gap (K) for the writing medium is formed between the graphic carrier (4) lying against the projecting end of the rolling element and the face (3, 3') of the drawing end (1, 1', 1''), and the face (3, 3') has grooves (13) which run from inside to outside and have crosssectional dimensions of capillary action.
2. A drawing implement as claimed in claim 1, characterized in that the rolling element takes the form of a ball (2) and is preferably arranged centrally in the face (3, 3').
3. A drawing implement as claimed in claim 2, characterized in that the hall (2) is of metal or carbide.
4. A drawing implement as claimed in claim 2 or claim 3, characterized in that the ball (2) is mounted in the drawing end (1,1',1'') with a clearance preferably forming capillary forces and is supported at the rear in that area of the drawing end (1, 1', 1'') which is opposite the face (3, 3') by at least two retentive, preferably web-like abutments (5) whose contact surfaces (6), suitably sloped ones, are on contact with the ball (2) along a small circle or are in punctiform contact therewith.
5. A drawing implement as claimed in any one of claims 2 to 4, characterized in that at least the area of the drawing end (1, 1', 1'') surrounding the ball (2) is made of preferably elastically expandible plastics material.
6. A drawing implement as claimed in any one of claims 2 to 5, characterized in that the drawing end (1, 1'') is one-piece.
7. A drawing implement as claimed in any one of claims 2 to 5, characterized in that the drawing end (1') is multipart and preferably composed of two intermateable parts (11a, 11b) which are rotationally symmetric at their mating areas (12a, 12b).
8. A drawing implement as claimed in any one of claims 2 to 7, characterized in that a writing medium reservoir (10) filled with China ink or ink is provided in the drawing implement (8).
9. A drawing implement as claimed in any one or more of claims 2 to 8, characterized in that the grooves (13) running from inside to outside are radially arranged.

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