EP0035736B1 - Writing tip, particularly for funnel type pens - Google Patents

Description

The invention relates to a pen tip, in particular a tube pen tip with from behind on the writing tube, the writing tip or the like in its front end. supporting cylinder body push-on writing liquid tank or push-on writing liquid cartridge, which carries a compensation chamber on the outer surface of the front end region, which ends in a connecting bore extending through the wall of the writing liquid tank or the writing liquid cartridge and is covered by a sleeve part between the and the Cylinder body the front end of the compensation chamber is connected to the ambient air.

In a known tube recorder tip of this type (DE-A-1 967 021), the sleeve part is formed in one piece with the cylinder body, so that an annular space open to the rear is provided between the sleeve part and the cylinder body and openings are provided in the connection area between these two components. A ink tank or ink cartridge is inserted into the annulus, which carries a spiral-shaped ink compensation chamber on the outer surface of the front end area, the front end of which, via the openings between the sleeve part and the cylinder body, with the ambient air, and the rear end of which via the connection hole with the room is connected adjacent to the drop weight body held in the cylinder body. This compensation chamber is covered by the sleeve part. The outer wall of the cylinder body has a relatively short axial length, so that it ends far in front of the connecting bore and this is not covered by the wall of the cylinder body. Rather, the connecting bore is in direct connection with the ink that comes from the tank or from the cartridge into the cylinder body and the writing tube.

With this known tube recorder tip, the ink compensation chamber can be cleaned very easily because it is located on the ink tank to be removed for refilling, so that only the ink tank needs to be completely cleaned before refilling, in order to make the ink compensation chamber that is often filled with dried ink functional again close. When using an ink cartridge, it is not even necessary to clean the ink compensation chamber in this way, but the soiled ink compensation chamber is automatically replaced by a clean ink compensation chamber when a new ink cartridge is inserted. However, in this known tube recorder there is a relatively large pressure difference between the front end of the writing tube and the connecting bore, since these two are at a relatively large distance from one another, that is to say there is a relatively large ink column with corresponding static pressure between them. Therefore, this ink compensation chamber does not achieve optimal pressure compensation. In addition, the compensation chamber is relatively short and thus only has a relatively small volume for receiving ink, the ink entering the compensation chamber directly from the annular space between the ink tank or ink cartridge and drop weight body through the connecting hole in the event of overpressure. Therefore, there is also the danger that when attempting to make the writing instrument capable of writing by spinning movements, ink will be thrown out of the openings between the sleeve part and the cylinder body at the front.

It is an object of the invention to improve a pen tip, in particular a tube pen tip, in such a way that, while maintaining the easy cleaning of the ink compensation chamber when using a writing fluid tank or while completely avoiding such cleaning when using a writing fluid cartridge, a small pressure difference between the front end of the writing tip and connection of the compensation chamber to the writing fluid supply area is achieved, the compensation chamber also being said to have a relatively large volume.

To achieve this object, a pen tip of the type mentioned at the outset is designed in such a way that an inner compensation chamber is provided on the inner surface of the front end region of the write liquid tank or the write liquid cartridge, the rear end of which is connected to the connecting bore such that the entire inner compensation chamber and the Connection bore are covered by the outer surface of the cylinder body and that a transverse bore connected to the inner bore is provided in the front end region of the cylinder body, which is connected to the front end of the inner compensation chamber.

In the pen according to the invention there is therefore an equalizing chamber both on the inner surface and on the outer surface of the front end region of the writing fluid tank or the writing fluid cartridge, and these equalizing chambers are connected to one another via the connecting hole, while the writing fluid enters the inner equalizing chamber at the front end. where a transverse bore is provided in the wall of the cylinder body, the wall of which also extends axially relatively far to the rear in order to cover the entire inner compensation chamber and the connecting bore. As a result of the transverse bore in the front end area of the cylinder body, there is a small distance between the front end of the writing tip and the entry area of the writing fluid into the compensation chamber and thus a low pressure difference, as well as a relatively long, i.e. large-volume compensation chamber, because the writing fluid initially advances in the inner compensation chamber at the back, then through the connecting hole and then from the connecting hole in the outer compensation chamber to the front. Since, moreover, the compensation chamber is only partially filled in normal operation, that is to say there is generally only writing fluid in the inner compensation chamber, there is also no danger of writing fluid being thrown out of the compensation chamber to the front when the pen tip is shaken.

It is already known in tube recorders (DE-U-1 947 421 and DE-B-1 278 284) to connect the inner bore of the cylinder body in the front area with an ink compensation chamber, which is connected to a radially outer one via a connection bore located further back Ink compensation chamber communicates. This radially outer ink compensation chamber is connected to the ambient air at the front end. This also results in the advantages of a low pressure difference and a large-volume compensation chamber, but this design is a relatively complicated tube pen tip made of at least three different molded parts, which together form the cylinder body and the two compensation chambers, with the cleaning of the compensation chambers being proportionate great disassembly and assembly work is connected, while is while the writing fluid tank or the writing fluid cartridge is attached from behind to the pen tip thus formed.

In the area behind the compensation chamber located on the outer surface, an external thread for screw engagement with an internal thread provided in the rear end region of the sleeve part can be present on the writing liquid tank or the writing liquid cartridge of the inventive pen tip, so that the sleeve part, and if this is made in one piece with the cylinder body is, the cylinder body can be firmly and captively connected to the writing fluid tank or the writing fluid cartridge.

A radially outwardly directed annular shoulder can be provided behind the outer compensation chamber or behind the external thread, against which the rear end of the sleeve part rests, thereby ensuring a defined position of the writing liquid tank or cartridge relative to the sleeve part.

In a further embodiment of the pen tip according to the invention, in which the writing liquid tank or the writing liquid cartridge is made of softer plastic than the sleeve part, sawtooth-shaped projections can be provided on the rear end surface of the sleeve part in its axial direction, the longer tooth surfaces of which opposite to the screwing-on direction of the sleeve part rise, and on the writing fluid tank or the writing fluid cartridge, behind the ring shoulder there may be an external thread having the same direction as the external thread in front of the ring shoulder for fastening a holder shaft. Through such sawtooth-shaped projections in the sleeve part made of harder material, this is anchored when screwing onto the writing fluid tank or the writing fluid cartridge in the front surface of the ring shoulder and is more difficult to loosen than the screwed-on holder shaft. In this way it is avoided that the user accidentally loosens the sleeve part when trying to unscrew the holder shaft and thus exposes the outer compensation chamber. Rather, the holder shaft is always released first, and then the user can grip the writing liquid tank or the writing liquid cartridge and separate it from the sleeve part by unscrewing it.

• Fig. 1 zeigt teilweise als Ansicht teilweise im Schnitt eine Röhrchenschreiberspitze mit aufgeschraubtem Halterschaft.
• Fig. 2 zeigt in einer Draufsicht das hintere Ende des Hülsenteils.
• Fig. 3 zeigt einen Teilschnitt entlang der Linie 111-111 aus Fig. 2.

In order to assemble the pen tip from individual parts that are particularly easy to produce by injection molding and to also be able to easily clean the cylinder body if necessary, the cylinder body and the sleeve part can be separate components, and the cylinder body can have an annular shoulder in its front end region, which is on the front edge of the Writing liquid tanks or the writing liquid cartridge abuts and is held in position by the radially inwardly drawn front edge of the sleeve part.
The invention is explained in more detail below with reference to the figures showing an exemplary embodiment:

• Fig. 1 shows partly as a view, partly in section, a tube pen tip with a screwed-on holder shaft.
• Fig. 2 shows a top view of the rear end of the sleeve part.
• FIG. 3 shows a partial section along the line 111-111 from FIG. 2.

The tube pen tip shown contains a cylinder body 1, in the front end of which the tube 4 is held by means of a metal holder 3 embedded in the cylinder body 1. In the inner bore of the tubular cylinder body 1 there is a drop weight body 2, in the front end of which the cleaning wire is fastened in a manner not shown, which extends into the writing tube and can be moved back and forth with the drop weight body 2 in the axial direction. In the rear end of the cylinder body 1, a falling weight safety device 5 having a central opening is inserted. In the front end region of the cylinder body 1 there is a transverse bore 7 which connects the outer cylinder surface of the cylinder body 1 with its inner bore.

A ink tank 11 is attached to the cylinder body 1 from the rear and bears with its front edge against an annular shoulder 18 of the cylinder body 1. In the front end region of this ink tank 11 there is a helical compensation chamber 14 in the inner surface, the front end of which is connected to the transverse bore 7, while its rear end is connected to a connecting bore 13 extending through the wall of the ink tank 11. This inner ink compensation chamber is covered by the outer cylindrical surface of the cylinder body 1, which is in essentially sealing engagement with the inner surface of the ink tank 11. From the connecting bore 13 extends in the outer surface of the ink tanks 11 a helical ink compensation chamber 12 to the front, and behind this outer ink compensation chamber 12 an external thread 16 is provided, which ends at a radially outwardly directed annular shoulder 15. a sleeve part 9 is screwed onto the thread 16 from the front, which covers the compensation chamber 12 and has openings 10 at the front end between itself and the cylinder body 11 forms that connect the front end of the ink balancing chamber 12 with the ambient air. Otherwise, the front, radially inwardly drawn edge of the sleeve part 9 holds the cylinder body 11 by abutment against the annular shoulder 18 of the cylinder body in the ink tank 11. The rear end of the sleeve part 9 touches the annular shoulder 15 of the ink tank 11.

Thus, in the tube pen tip shown in FIG. 1 in the assembled state, the sleeve part 9 can be removed forwards by unscrewing the thread 16, and the ink tank 11 can then be pulled backwards from the cylinder body 1. The ink tank exposed in this way can be cleaned and refilled, and during cleaning the compensation chambers 12 and 14 and the connecting bore 13 can also be cleaned without requiring special cleaning of the cylinder body 1 or the sleeve part 9. The newly filled ink tank 11 is then put back on the cylinder body 1, and the two elements are connected to one another by screwing on the sleeve part 9.

Behind the annular shoulder 15 there is an external thread 17 on the ink tank 11, onto which a holder shaft 6 is screwed.

While a ink tank is shown in the illustrated embodiment, a correspondingly designed ink cartridge can of course also be used, i.e. an ink container, which was filled by the manufacturer and closed on both sides, but whose front closure lies behind the connecting bore 13 and is broken through by plugging onto the cylinder body 1 from its rear end or from the drop weight safety device 5.

As can be seen in FIGS. 2 and 3, sawtooth-shaped projections 20 are formed in the rear end face of the sleeve part 9, which protrude with their tooth faces 21, 22 from the end face, as can be seen in particular in FIG. 3. The longer tooth surface 21 rises in the opposite direction of the thread of the fastening thread 16 for the sleeve part 9, i.e. in the case of a conventional right-hand thread, the rise, viewed from the front end of the sleeve part 9, takes place in a counterclockwise direction.

When the sleeve part 9, which is made of relatively hard plastic, is screwed on, the projections 21 "dig" somewhat into the front surface of the ring shoulder 15 of the writing fluid tank 11, which is made of softer plastic, so that the sleeve part 9 is anchored to a certain extent. In this way, it is avoided that the user, who holds the writing instrument with one hand on the sleeve part 9 and with the other hand on the holder shaft 6 to unscrew the holder shaft 6, accidentally loosens the sleeve part 9 instead of the holder shaft 6, because the resistance to this Loosening this sleeve part is due to the "anchoring" by means of the projections 20 greater than the resistance to loosening the holder shaft 6. Only when the holder shaft 6 is unscrewed and the user holds the pen tip on the ink tank 11 can the sleeve part 9 be easily removed.

It should be pointed out that to cover writing tubes 4 and compensation chamber 12 connected to the ambient air, a cover cap can be applied to the sleeve part 9. For this purpose, an external thread, not specified, is present on the sleeve part.

Claims (5)

1. Pen tip, in particular capillary pen tip with a writing fluid reservoir (11) or writing fluid cartridge, able to be pushed from the rear onto the cylindrical body (1) carrying in its front end the writing capillary (4), the writing tip or suchlike, which reservoir or cartridge on the outer surface of the front end region carries an equalizing chamber (12), which terminates in a connecting bore (13) extending through the wall of the writing fluid reservoir (11) or writing fluid cartridge, and which is covered by a sleeve piece (9), between which and cylindrical body (1) the front end of the equalizing chamber (12) is connected with the surrounding air, characterized in that on the inner surface of the front end region of the writing fluid reservoir (11) or writing fluid cartridge, an inner equalizing chamber (14) is provided, the rear end of which is connected with the connecting bore (13), that the entire inner equalizing chamber (14) and the connecting bore (13) are covered by the outer surface of the cylindrical body (1), and that in the front end region of the cylindrical body (1) a transverse bore (7) is provided, which is connected with the inner bore, and communicates with the front end of the inner equalizing chamber (14).

2. Pen tip according to claim 1, characterized in that on the writing fluid reservoir (11) or writing fluid cartridge, in the region behind the equalizing chamber (12) which is located on the outer surface, an external thread (16) is present, and that the sleeve piece (9) in the rear end region has an internal thread for engagement with the external thread (16).

3. Pen tip according to claim 1 or 3, characterized in that on the writing fluid reservoir (11) or writing fluid cartridge, behind the equalizing chamber (12), which is located on the outer surface, or behind the external thread (16), an annular shoulder (15) is provided, which is directed radially outwards, and that the rear end of the sleeve piece (9) rests against the annular shoulder (15) when the writing fluid reservoir (11) or writing fluid cartridge has been pushed on.

4. Pen tip according to claim 3, with a writing fluid reservoir or a writing fluid cartridge, which consists of softer synthetic material than the sleeve piece, characterized in that on the rear end face of the sleeve piece (9) saw-tooth shaped projections (20) are provided, rising in its axial direction, the longer tooth faces (21) of which rise towards the direction of the screwing on of the sleeve piece (9), and that on the writing fluid reservoir (11) or writing fluid cartridge behind the annular shoulder (15) an external thread (17) is present to fasten a holder shaft (6), and which thread has the same thread direction as the external thread (16) provided in front of the annular shoulder (15).

5. Pen tip according to claim 3 or 4, characterized in that cylindrical body (1) and sleeve piece (9) are separate component parts and the cylindrical body has an annular shoulder (18) in its front end region, which rests against the front edge of the writing fluid reservoir (11) or the writing fluid cartridge and is held in its position by the front rim of the sleeve piece (9) which is drawn radially inward.

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