The invention relates to an ink feed component for a fountain pen. There are known in the art ink feed components which include a main body provided with radial ink-holding chambers, located intermediate forward and rearward ends thereof. The forward end is provided with a nib supporting surface, while the rearward end is adapted for connection to the ink reservoir of the fountain pen. On the nib support side of the ink feed, an axially extending groove is provided for receiving an inset, such that between the inset and the base of the groove, an air channel and at least one capillary ink feed channel are formed.
In a known ink feed of this type (DE-AS 1 034 066) two capillary ink feed channels extend in the base of a groove forming an air channel in the main body, and connect the rear end of the main body with the nib support surface. These two ink feed channels deviate in the region of the front end of the main body from their otherwise straight course, by curving towards the nib support surface, so that they emerge on the nib support surface, and so that direct wetting of the under side of the nib takes place with ink from the ink feed channels.
In practice, it has been discovered that in many cases the continuity of the ink film breaks between the nib and the exit openings of the ink-feed channels when the nib spreads slightly (due to increased writing pressure) and is lifted from the nib support surface of the ink feed. It is also possible, particularly with nibs used for wider lines, and when there is a greatly fluctuating writing pressure, that the ink feed channels are not capable of automatically supplying the larger quantity of ink required under such circumstances.
The object of this invention is to provide an ink feed in which the ink film between the ink feed and the nib does not break, even under increased writing pressure.
To achieve this object, an ink feed of the type specified in the introduction is improved in accordance with this invention, such that the front end of the ink feed channel opens into an ink reserve chamber formed between the main body and the inset, and such that the ink reserve chamber is connected to the nib support surface via a capillary ink exit slit located between the front end area of the inset and the main body. This ink exit slit extends from the longitudinal axis of the ink feed, (which extends through the center of the groove), out to its two sides, with at least partial side sections extending to the rear.
In the ink feed according to the invention, the supply of ink to the nib does not therefore take place directly from the capillary ink feed channel or channels, but from an ink reserve space charged by one or more of the channels, so that even when there is greater ink consumption, sufficient ink can be drawn from the ink reserve space, which forms a type of buffer. Due to this arrangement, there is surprisingly an almost complete suppression of the pressure fluctuations, caused by other pressure fluctuations in the ink reservoir due to consumption of ink and entry of air, which otherwise occur in the region of transfer to the nib and accompanying retraction of the ink meniscus.
As indicated above, the supply of ink from the ink reserve space to the nib takes place via a capillary ink exit slit, the front area of which lies directly below the nib groove. The slit also extends both to the side and to the rear, so that when not in use or when there is low writing pressure, wetting of the nib takes place through the entire ink exit slit including the region immediately below the nib groove even when the nib is not positioned in the exact center. When there is increased writing pressure, resulting in the spreading of the nib, the ink film between the region of the ink exit slit lying directly below the nib groove and the nib may be broken; however, an ink film is reliably maintained between the remaining region of the ink exit slit and the nib on both sides of the nib groove.
In a related aspect of the invention, a high degree of ink evaporation from the ink reserve space is prevented by the ink exit slit. When the ink does evaporate, ink is additionally drawn again from the ink feed channel into the ink reserve space, thereby supplying ink to the ink exit slit. This produces very good start of writing performance.
The ink exit slit can, for example, be U-shaped, wherein the arms of the U extend directly to the rear but can, if desired, diverge outwardly to the rear. Additionally, the passage from the base of the U to its arms can take place via a rounded region or an angled region.
It is also possible to form the ink exit slit in the shape of a V or to form it in a curve such that the ends of the curve lie further to the rear than its central curved region.
In order to ensure that ink is fed to the writing nib when using nibs for wider lines, the distance between the neighboring sides of the main body and the inset which border on the ink reserve space can gradually decrease from the outlet region of the ink feed channel to the ink exit slit. In this way, a relatively large volume of ink is collected in the ink reserve space, and because the capillary forces act more strongly there due to the narrowing of the ink reserve space towards the ink exit slit, the ink is carried reliably to the ink exit slit and therefore to the writing nib.
As described, the ink reserve space can also taper to the front in a wedge-shape along the longitudinal axis of the ink feed which extends through the center of the groove.
As already mentioned above, by providing the ink reserve space and the ink exit slit according to the invention, a reliable supply of ink to the writing nib is ensured even under difficult writing conditions. The ink feed according to the invention is therefore suitable both for narrow-line nibs and for wider-line nibs.
In a preferred embodiment of the invention, the ink feed channel (channels) is (are), formed on the under side of the inset.
In this way, it is necessary to provide only one form of a main body for the ink feed, and to adapt the insets for nibs of different line widths by using an appropriately formed inset, with the ink feed channel or channels so dimensioned that they transport the appropriate quantity of ink to the front end of the ink feed, the inset being so formed that together with the main body it forms an ink reserve space and an ink exit slit with dimensions suitable for the current application.
When an inset of this type is used, transverse channels can be provided on the under side of the inset to connect with the radial ink holding chambers.
In order to be able to position the inset precisely in the main body so that an ink exit slit of the desired size can be obtained within the most narrow specifications, positioning projections can be constructed in the front end region of the inset on its side walls.
It has also proved advantageous to form the radius of curvature of the outer surface of the inset in the region of the nib support surface such that it is larger than the radius of curvature of the outer surface of the main body which joins in the circumferential direction, so that the radius of curvature of the outer surface of the inset exactly matches the radius of curvature of the nib. This results in a further improvement of the ink feed.
Further objects and advantages will become apparent from the detailed description which follows.