US3873218A

US3873218A - Writing instrument for low-viscous ink without an absorbing fibrous bundle

Info

Publication number: US3873218A
Application number: US347465A
Authority: US
Inventors: Kisaburo Yoshida
Original assignee: Sakura Color Products Corp
Current assignee: Sakura Color Products Corp; SAKURAKUREPASU KK
Priority date: 1972-04-26
Filing date: 1973-04-03
Publication date: 1975-03-25
Anticipated expiration: 1992-03-25
Also published as: IT986273B

Abstract

Writing instrument comprising a pen tip, a reservoir containing low-viscous ink, an ink feeding conduit extending from the pen tip into the reservoir and having an inner ink passageway extending therethrough, an air admission inside tube covering the conduit, with an annular air passage formed therebetween to permit a capillary action therein, and an air admission outside tube covering the inside tube, with a large space formed therebetween, and having an air port in its rear portion. The conduit is formed in its peripheral wall with a port positioned in the front end of the reservoir to permit the ink passageway to communicate with the interior of the reservoir. The opposite ends of the outside tube are closed, while the annular air passage has a front end open to the front portion of the outside tube and a rear end open to the front end of the reservoir, whereby the ink in the reservoir is rendered replaceable by air.

Description

United States Patent 11 1 Yoshida 51 Mar. 25, 1975 WRITING INSTRUMENT FOR LOW-VISCOUS INK WITHOUT AN ABSORBING FIBROUS BUNDLE [75] Inventor: Kisaburo Yoshida, Osaka, Japan [73] Assignee: Kabushiki Kaisha Sakurakurepasu,

Osaka, Japan [22] Filed: Apr. 3, 1973 [21] Appl. No.: 347,465

[30] Foreign Application Priority Data Apr. 26, 1972 Japan 4742508 [52] US Cl. 401/292, 401/209 [51] Int. Cl B43k 5/00 [58] Field of Search 401/292, 198, 199, 223, 401/224, 134, 209, 261

[56] References Cited UNITED STATES PATENTS 3,338,216 8/1967 Roller 401/292 X 3,361,516 1/1968 Rigondaud 401/292 3,501,225 3/1970 Martin et a1. I 401/198 3,614,248 10/1971 Otsuka 401/292 3,687,561 8/1972 Phillips 401/292 FOREIGN PATENTS OR APPLICATIONS 422,575 4/1967 Switzerland 401/198 swam? Primary E.\'aminer-Lawrence Charles Atlorney, Agent, or FirmLarson, Taylor and Hinds [57] ABSTRACT Writing instrument comprising a pen tip, a reservoir containing low-viscous ink, an ink feeding conduit extending from the pen tip into the reservoir and having an inner ink passageway extending therethrough, an air admission inside tube covering the conduit, with an annular air passage formed therebetween to permit a capillary action therein, and an air admission outside tube covering the inside tube, with a large space formed therebetween, and having an air port in its rear portion. The conduit is formed in its peripheral wall with a port positioned in the front end of the reservoir to permit the ink passageway to communicate with the interior of the reservoir. The opposite ends of the outside tube are closed, while the annular air passage has a front end open to the front portion of the outside tube and a rear end open to the front end of the reservoir, whereby the ink in the reservoir is rendered replaceable by air.

7 Claims, 6 Drawing Figures amaze:

PATENTEDHARZSISYS felllallllllfil sum 1 or z PATENTEUHARZWYB 3.873.218 sum 2 o 2 FIG 5 BACKGROUND OF THE INVENTION The present invention relates to writing instruments such as marking pens and ball-point pens having a reservoir which contains aqueous ink, alcoholic ink or like low-viscosity ink without using a conventional fibrous bundle.

With conventional writing instruments using aqueous ink or alcoholcontaining ink, ink inevitably flows out in a drop or to excess during writing when the amount of outflow of ink undergoes minute variations due to changes in the atmospheric pressure and temperature. This is the most serious problem heretofore encountered with writing instruments of the above-mentioned type, unlike those for use with high-viscosity ink such as ball-point pens for oily ink. For example, the body temperature is transmitted during writing from the fingers to the pen barrel to expand the air or ink in the pen barrel, thereby causing excess outflow of ink from the pen tip or from various clearances in the ink channel. In order to avoid such trouble, conventional marking pens employ a fibrous bundle for absorbing and retaining ink. However, the amount of ink contained in the pen barrel as absorbed by the fibrous bundle is extremely limited and, moreover, only about 50% of the total amount of the ink is actually usable for writing. Furthermore, the known structure fails to assure sufficient flow of ink for rapid writing. Consequently, the pen of the type described readily runs short of ink and is serviceable only for a very short period of time. It is also known that usual fountain pens have a nib support element formed with several flutes for preventing excess outflow of ink. It is, however, impossible to incorporate such element into a marking pen or ballpoint pen.

SUMMARY OF THE INVENTION It is therefore a main object of this invention to provide a writing instrument for low-viscosity ink including a structure in which an ink reservoir containing a large amount of ink without employing a fibrous bundle communicates with the atmosphere free of any leakage of ink and which is capable of automatically replenishing the reservoir with air at a rate corresponding to the consumption of ink, the structure further being such that even in the event of a change in temperature or atmospheric pressure, expanded air or ink in the reser-' voir can be released through an opening other than the ink passageway while keeping the ink in the passageway free of any influence so as to eliminate any excess outflow of ink and to ensure smooth flow of ink at a constant rate all the time for a prolonged period.

Another problem encountered with writing instruments for use with low-viscosity ink is that bubbles are likely to be formed in the ink passageway and, once formed, they interfere with capillary action within the passageway, rendering the instrument no longer serviceable.

Accordingly, a further object of this invention is to provide a writing instrument for low-viscosity ink in which formation of bubbles in the ink passageway is prevented and bubbles, even if formed, will not completely impede the flow of ink through the passageway, making it possible to use the whole amount of ink in the reservoir without leaving any droplet of ink.

Other objects and features of the present invention will become more apparent from the following description of preferred embodiments of the invention with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal sectional view ofa writing instrument embodying the present invention;

FIG. 2 is an enlarged view in section taken along the line A-A of FIG. I;

FIG. 3 is an enlarged fragmentary perspective view showing an ink feeding conduit partly broken away;

FIG. 4 is a longitudinal sectional view showing another embodiment of this invention;

FIG. 5 is a longitudinal sectional view showing another embodiment of this invention; and

FIG. 6 is an enlarged view in section taken along the line B-B of FIG. 5.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The writing instrument of this invention for a lowviscosity ink basically comprises a reservoir 1 which contains a large amount ofink without an ink absorbing fibrous bundle, a pen tip 2, and an ink feeding conduit 3 connecting the reservoir 1 to the pen tip 2 so that ink 4 within the reservoir 1 is fed to the pen tip 2 by the capillary action of the ink feeding conduit. The instrument of this invention is characterized by a structure for substituting air for ink by which the ink reservoir is automatically replenished with an amount of air corresponding to the consumption of ink. This structure for substituting air for ink will first be described in detail.

An air admission inside tube 5 and an air admission outside tube 6 are usually molded of synthetic resin and cover the ink feeding conduit 3 extending between the front end of the reservoir 1 and the pen tip 2. The air admission outside tube 6 has a connecting portion 7 at its back end, a constricted portion 8 at the front end thereof, and a port 9 at a rear portion thereof. The reservoir l is tightly fitted around the connecting portion 7, and the constricted portion 8 firmly holds the ink feeding conduit 3. The air admission inside tube 5 is smaller in diameter than the air admission outside tube 6. Between the inner peripheral surface of the inside tube 5 and the outer peripheral surface of the outside tube 6, there is formed a very small annular clearance 10 as an air passage, such that when the ink is introduced into the air passage 10, a powerful capillary action will be produced therein. The inside tube 5 has a thick back end 11 which is tightly fitted in the back end of the air admission outside tube 6, thereby keeping the back end of the air passage 10 open to the front end of the reservoir 1. The front end of the annular passage 10 is open to the inner front portion of the air admission outside tube 6. The clearance between the air admission inside tube 5 and the air admission outside tube 6 is formed as widely as possible so that ink will not be drawn by capillary action from the front portion to the rear portion of the air admission outside tube 6 even if a small amount of ink is deposited in the front portion of the tube 6.

Various types of the ink feeding conduit 3 and the pen tip 2 will now be described in detail.

FIGS. 1 to 3 show an ink feeding conduit 3a made of a wear resistant material such as acetal resin and having a very fine ink passageway 12 which is accurately diseen in cross section, the passageway 12 comprises a plurality of radial channels P each of which is tapered toward the center Q of the conduit 3a in the form of an elongated isosceles triangle, the channels P communi eating with one another at their vertexes, i.e., at the center Q. The shape of the ink passageway 12 is not limited to that shown but the passageway may be of any shape insofar as it has a very small clearance which will induce a very effective capillary action, such that bubbles, if any in the ink, will not block up the passageway 12 to interrupt the flow of ink through the passageway 12. Thus the constituent channel or the passageway must at least be noncircular in cross section. Especially in the case where the passageway 12 comprises a plurality of channels P which are in the form of an isosceles triangle and which communicate with one another at the center Q as in the present embodiment, the ink will be drawn toward a narrower portion. Consequently the ink flows three-dimensionally, i.e., in the axial direction and from the peripheral portions of the passageway toward the center in a plane perpendicular to the axial direction. This is the most preferable mode of supply of ink to the center of the pen tip. The ink feeding conduit 3 extends from a rear portion of the reservoir l to the pen tip 2 coaxially with the air admission inside tube 5 and the air admission outside tube 6. A port 13 for releasing air and admitting ink is formed in the peripheral wall of the ink feeding conduit 3, at a position in the front end of the reservoir 1. The port 13 communicates with the ink passageway 12 and serves to release air (bubbles) from the passageway 12. Through the port 13, the ink in the front portion of the reservoir 1 is introduced into the passageway by the capillary action and vacuum of the interior of the passageway during writing. As a rule, the air and ink port 13 is positioned only in the front end of the reservoir 1. However, another port may be formed in a portion of the conduit corresponding to the midportion or rear portion of the reservoir 1. An auxiliary air and ink port 14 formed in the peripheral wall of the ink feeding conduit 3 is positioned in the front end of the air admission outside tube 6, and has substantially the same function as the aforementioned air and ink port 13 in the reservoir 1 except that whereas the air and ink port 13 takes in the ink within the reservoir 1, the auxiliary air and ink port 14 draws in the ink collected in the front portion of the air admission outside tube 6. More specifically although the ink which has flowed into the air passage is usually retained therein by surface tension since the air passage 10 is in the form ofaminute clearance, some ink in the air passage 10 may possibly be deposited in the front portion of the air admission outside tube if the pen is left unused with its tip down. When the pen is then put to use, the ink is withdrawn from the front portion into the conduit 3 through the port 14. The writing instrument is operable free of any trouble without the auxiliary port 14, but experiments have revealed that the provision of the auxiliary port 14 permits the writing instrument to display superior performance.

The tip 2a shown in FIG. 1 is formed by cutting the end of the ink feeding conduit 3a into a conical shape. The ink passageway inside the conduit 3a is therefore exposed on the conical surface of the ink feeding conduit 3a, and ink flows through the ink passageway concentrically to the center 0 at the pen tip 2a.

The ink feeding conduit 3a in FIG. 4 has the same construction as that illustrated in FIGS. 1 to 3. As in the foregoing embodiment, the ink passageway 12 therein is not limited to the shape in which channels are arranged radially in cross section but may be of any cross sectional shape other than circular form insofar as the passageway will induce an effective capillary action and will not be blocked up with bubbles. The pen tip 2b of FIG. 4 comprises a ball-point pen tip 16 of metal or synthetic resin fitted around the front end of the ink feeding conduit 3a. The ball-point pen tip has a ball 15 in its top. The end surface of the ink feeding conduit 3a serves to seat the ball 15. The ball-point pen tip may be of any construction if ink can be transferred from the feeding conduit onto paper.

The ink feeding conduit 3b in FIG. 5 comprises a slender tube 17 and several smooth-surfaced linear elements 18 such as nylon wires or stainless steel wires inserted in the tube 17 and extending over the entire length of the tube 17 to provide an ink passageway 19 in the form of minute clearances between the linear elements l8 and the peripheral inner surface of the tube 17 and amongst the linear elements themselves. In other respects, this ink feeding conduit 3b is identical to the ink feeding conduit 30 shown in FIG. 1. The pen tip 20 in FIG. 5 comprises a ball-point pen tip 21 made of metal or synthetic resin and having a ball 20 in its top end and a rear portion 22 receiving the ink feeding conduit 3b. A small bore 23 is formed in the front portion of the tip 21. A single element 18' among the linear elements 18 within the ink feeding conduit 36 is inserted in the small bore 23, with the end of the element 18' in contact with the ball 20. During writing, the rolling ball 20 shakes the linear element 18' in contact therewith, thereby feeding ink from the conduit 3h onto the ball 20.

In FIGS. 4 to 6, indicated at 24 is a pen barrel and at 25, an air port formed in a suitable portion of the pen barrel 24. The reservoir 1 and the air admission outside tube 6 need not always be covered with the pen barrel 24. Where an elongated reservoir is used and connected to the outside tube, the assembly serves as a pen barrel. In the drawings, theparts referred to by the same reference numerals and characters have the same construction and function in the same manner.

The reservoir 1 may be of the interchangeable or disposable cartridge type or may be adapted for replenishment.

When the reservoir 1 filled with ink is tightly fitted to the connecting portion 7 of the air admission outside tube 6, the ink 4 is instantaneously introduced into the ink feeding conduit 3a or 312 from its rear end as well as through the air and ink port 13 and is fed to the pen tip 2a, 212 or 26 by powerful capillary action of the

ink passageway

12 or 19, while permitting air to escape from the

ink passageway

12 or 19 through the air and ink port 13, auxiliary port 14, and pen tip. Even if air should remain in the

ink passageway

12 or 19, the air is in the form of fine bubbles and will not block up the entire cross sectional area of the

passageway

12 or 19, since the passageway 12 comprises radially arranged channels and is not circular in cross section, whilst the passageway 19 comprises clearances among several linear elements 18. Thus the bubbles will in no way interrupt the flow of ink, permitting effective capillary action. When air is introduced into the

ink feeding conduit

3a or 3b during writing, the conduit similarly functions effectively to assure satisfactory capillary action. Inasmuch as the

ink passageway

12 or 19 comprises minute channels or clearances as described above, the ink fed to the

pen tip

2a, 2b or 2c is effectively retained in the

ink passageway

12 or 19 by virtue of high surface tension when the pen is not in use. Furthermore, ink 4 is always kept in contact with the inlet of the ink feeding conduit 3a or 312 whether the pen is left for a long time in horizontal position or in upright position with its tip up, because the

conduit

3a or 3b extends to the back end of the reservoir 1 and has the air and ink port 13 positioned in the front end of the reservoir 1. Thus the pen tip 2a, 212 or is wet with the ink all the time, ready for writing.

When the pen is put to use for writing, the friction of the

pen tip

20, 2b or 2c with paper and the ability of paper to absorb ink cause the ink to continuously flow out of the

ink passageway

12 or 19 toward the pen tip, whilst the vacuum and capillarity in the interior of the

ink feeding conduit

30 or 3b force the ink in reservoir 1 to flow into the

passageway

12 or 19 from the rear end and/or the air and ink port 13 of the conduit. At a rate corresponding to the consumption of ink, air is supplied to the reservoir 1 from an air port of the pen barrel 24, through the port 9 of the air admission outside tube 6 and then through the annular passage of the air admission inside tube 5. Thus substitution of air for ink can be effected smoothly.

The air passage 10 of the air admission inside tube 5 plays an important role in the foregoing operation. That is to say, during writing with the pen tip down, some of ink 4 flows into the annular passage 10 from its open rear end, but the annular passage which is in the form of the smallest possible clearance permits a high surface tension to act to effectively retain the ink therein. Consequently, hardly any ink will flow out into the air admission outside tube 6. When the writing instrument is used, with the ink effectively retained within the annular passage 10, a vacuum is created in the reservoir 1, whereby air is introduced in the form of fine bubbles into the ink in the passage 10 by way of the ports already described and is eventually withdrawn into the reservoir 1 together with the ink.

Thus although the annular passage 10 is open to the front end of the reservoir 1, the passage 10 which is a small clearance enables a high surface tension to act to retain the ink within the passage 10, without allowing hardly any ink to flow into the outside tube 6 even if the pen is shaken forcibly. During writing, the vacuum produced in the reservoir draws air through the tube 6 into the reservoir in the form of fine bubbles along with the ink held in the annular passage 10. In this way, the ink in the reservoir can be replaced by air without any trouble notwithstanding that the annular passage 10 is blocked with ink. Although the air passage 10 at the front end of the reservoir communicates with the atmosphere, the annular passage functions to assure substitution of air for ink without permitting ink to leak out. This is the most distinct feature of this invention.

Furthermore, even if some of ink retained in the passage 10 should be deposited in the front portion of the air admission outside tube 6, the ink will be drawn into the

ink feeding conduit

3a or 3b during writing, if the anxiliary air and ink port 14 is formed in the conduit at that position.

The air in the reservoir may expand due to changes in temperature or atmospheric pressure, but some air can be released through the annular passage 10, thereby preventing excess outflow of ink. For the same reason, insufficient flow of ink can be avoided in the event of contraction of air in the reservoir.

The air and ink port 13 formed in the

ink feeding conduit

3a or 3b and positioned in the front end of the reservoir 1 makes it possible to use up the ink in the reservoir without leaving almost any droplet of ink.

I claim:

1. A writing instrument for low-viscous ink comprising a pen tip, a reservoir containing said ink without employing an ink absorbing fibrous bundle, an ink feeding conduit extending from said pen tip into said reservoir to its rear portion and having an inner ink passageway extending throughout the entire length thereof, said conduit having in its peripheral wall a port positioned in the front end ofsaid reservoir and permitting said ink passageway to communicate with the interior of said reservoir, an air admission inside tube covering said conduit and forming an annular air passage between the inner peripheral surface of said air admission inside tube and the outer peripheral surface of said conduit which annular passage permits capillary action therein, an air admission outside tube covering both said conduit and said inside tube and being closed at its opposite ends so that a sufficiently large space is formed between said inside and outside tubes to prevent ink from being drawn by capillary action from the front portion of said outside tube toward its rear por tion, said air admission outside tube having in its rear portion an air port for permitting the interior of said air admission outside tube to communicate with the atmosphere, said annular air passage having a front end open to the front portion of said outside tube and a rear end open to the front end of said reservoir, whereby the ink in said reservoir is rendered replaceable by air.

2. A writing instrument for low-viscous ink according to claim 1, in which said ink passageway comprises a plurality of channels radially arranged in cross section and communicating with each other at the center of the passageway.

3. A writing instrument for low-viscous ink according to claim 2, in which said ink feeding conduit is made of synthetic resin.

4. A writing instrument for low-viscous ink according to claim 3, in which the front end of said ink feeding conduit is conically cut to serve as said pen tip.

5. A writing instrument for low-viscous ink according to claim 4, in which said ink feeding conduit has a port formed in the peripheral wall thereof and positioned in the front end of said air admission outside tube, the ink passageway communicating with the space between said inside and outside tubes through said port.

6. A writing instrument for low-viscous ink according to claim 5, in which the front end of said ink feeding conduit has a ball-point pen tip fitted therein and serving as said pen tip.

7. A writing instrument for low-viscous ink according to claim 1 in which several linear elements are inserted into the ink feeding conduit, said ink passageway comprising the clearances among said linear elements, and the front end of said conduit has a ball-point pen tip serving as said pen tip.

Claims

1. A writing instrument for low-viscous ink comprising a pen tip, a reservoir containing said ink without employing an ink absorbing fibrous bundle, an ink feeding conduit extending from said pen tip into said reservoir to its rear portion and having an inner ink passageway extending throughout the entire length thereof, said conduit having in its peripherAl wall a port positioned in the front end of said reservoir and permitting said ink passageway to communicate with the interior of said reservoir, an air admission inside tube covering said conduit and forming an annular air passage between the inner peripheral surface of said air admission inside tube and the outer peripheral surface of said conduit which annular passage permits capillary action therein, an air admission outside tube covering both said conduit and said inside tube and being closed at its opposite ends so that a sufficiently large space is formed between said inside and outside tubes to prevent ink from being drawn by capillary action from the front portion of said outside tube toward its rear portion, said air admission outside tube having in its rear portion an air port for permitting the interior of said air admission outside tube to communicate with the atmosphere, said annular air passage having a front end open to the front portion of said outside tube and a rear end open to the front end of said reservoir, whereby the ink in said reservoir is rendered replaceable by air.