JP4590800B2 - Writing instrument - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention has a cylindrical body that opens at the rear end and communicates with the outside air as an ink tank that stores ink in a free state, and has a high viscosity that moves following the ink interface as the ink is consumed. A mobile stopper at least partially immersed in the composition and the high-viscosity composition is disposed, a barrier capable of contacting the mobile stopper is disposed in the vicinity of the rear end opening of the cylindrical body, and the rear side of the mobile stopper is disposed on the barrier The present invention relates to a writing instrument that opens a vent hole that communicates with the outside air, and closes the flow of the ink and the high-viscosity composition to the cylindrical rear end opening when the barrier and the moving stopper come into contact with each other.
[0002]
[Prior art]
Traditionally, writing instruments that store ink in an ink tank in a free state are not impregnated with ink, such as fiber converging bodies or porous bodies, but are called fresh ink-type writing instruments. There are advantages such as ejection and consumption of a large amount of ink without waste. In such a raw ink type writing instrument, ink leakage should be considered in particular, and it is made to be sealed except for a controlled ink distribution part such as an ink supply path to the pen tip. It is common. It is also known that a temporary ink reservoir member having a comb-like longitudinal section is interposed between the nib and the ink tank, which communicates the air passage into the ink tank with the outside as it is. However, it is devised so that the ink does not reach the opening part to the outside of the air passage as much as possible by utilizing the capillary force.
[0003]
The ink tank of the raw ink-type writing instrument as described above also needs to take in the outside air for the ink volume that decreases as the ink is consumed. become. Therefore, it is necessary to replace the volume of the consumed ink with another. Normally, air is taken into the ink tank by changing the internal pressure due to the ink being consumed by opening the air passage to the outside. In addition to the ink that is directly taken into the ink tank and replaced with the consumed ink, there is also an ink tank that changes the volume of the ink tank itself so that the ink tank volume automatically corresponds to the remaining amount of ink. For example, the ink tank itself is made by blow molding or a soft material that is relatively easy to deform, such as a bag, and the ink volumetric ink tank is crushed or the ink tank follows the ink interface. In some cases, the volume of the ink tank is always arranged so that the volume of the ink tank is almost equal to the volume of the ink existing in the ink tank.
[0004]
Such a type that changes the ink tank volume in accordance with the remaining amount of ink is arranged with a moving wall, and a high-viscosity fluid that prevents the ink from leaking over the moving wall is provided. There are known a backflow preventer disposed at the ink interface position, and a movable stopper that is a partly or fully immersed member adjusted by the specific gravity relationship with the backflow preventer.
[0005]
[Problems to be solved by the invention]
In order for the moving wall described above to be able to move by being pulled by the pressure of decompression due to ink consumption, it must be able to move with a relatively weak force, which is a problem in certain situations was there. That is, the backflow prevention body and this and the movable stopper move backward due to impact such as when the writing instrument is dropped, or when the pen tip is a ballpoint pen, the impact when dropping or rotates during writing The ball may come off due to wear caused by the ball rubbing against the ball-point pen tip. This causes a hole in the ball-point pen tip, and the ink tank communicates with the atmosphere. In addition to moving backward, when air is present in the ink tank, it may be pushed backward due to an increase in the volume of the air at high temperatures. Due to these phenomena, when the moving stopper moves backward, the moving stopper comes out from the rear end opening of the ink tank, so that there is a barrier provided on the tail plug or the like to prevent the moving stopper from coming off. However, the sealing reliability is not satisfactory, and a gap occurs in the contact portion, and the high viscosity composition that is a fluid flows through the gap due to impact, water head pressure, and pressure due to an increase in the volume of air. There was a concern that the backflow prevention function could not be maintained, leading to ink leakage from the portion.
[0006]
[Means for Solving the Problems]
That is, the present invention has a cylindrical body that opens as the ink tank for containing ink in a free state and communicates with the outside air, and moves along the ink interface as the ink is consumed. A high-viscosity composition and a mobile stopper at least partially immersed in the high-viscosity composition are disposed, a barrier capable of contacting the mobile stopper is disposed near the rear end opening of the cylindrical body, and the mobile stopper is disposed on the barrier In a writing instrument that opens a vent hole that allows communication between the rear side and outside air, and blocks the flow of the ink and the high-viscosity composition to the cylindrical rear end opening when the barrier and the moving stopper come into contact with each other. The gist of the writing instrument is characterized in that an annular convex portion is provided at the abutting portion of the stopper against the barrier and / or the abutting portion of the barrier against the movable stopper.
[0007]
[Action]
The contact portion between the movable stopper and the barrier is made into a state close to a line contact that is an infinitely small surface by an annular convex portion, and since the contact area is small, it is difficult to be influenced by the contact portion with respect to the other party, and a gap may be generated. Suppressed as much as possible. In addition, since the contact area is small, the contact pressure per unit area applied to the contact portion between the movable stopper and the barrier is larger than that of surface contact, so that the sealing performance can be further ensured. Therefore, even if the moving stopper moves backward due to impact, water head pressure, or increased air volume under high temperature, the flow of the high-viscosity composition, which is an ink backflow prevention body, can be reliably suppressed, thus suppressing ink leakage. can do.
[0008]
【Example】
An example will be described below with reference to the drawings.
The examples shown in FIGS. 1 to 4 are examples of so-called raw ink-type writing instruments that contain ink 1 in a free state that is not held in an ink occlusion body such as a fiber converging body. As shown in FIG. 1 where the whole is partially omitted, the metal ballpoint pen tip 2 is composed of polypropylene having excellent gas non-permeability and transparency so that the remaining amount of ink is visible. It is press-fitted and fixed to the distal end opening of the cylindrical body 3 which is a resin injection molded product. A synthetic resin tail plug 4 colored or dyed in an ink color capable of color display is press-fitted and fixed in the rear opening of the cylindrical body 3. The tail plug 4 is formed with an outside air communication hole 4a as an air flow passage. As the ink is consumed, outside air is taken into the rear of the movable stopper 5 in the cylinder 3, and the inside of the ink tank is not depressurized. Like that.
[0009]
The cylinder 3 contains ink 1 having a viscosity of about 100 mP · s and using water as a main medium and a pigment as a colorant. Further, as a backflow preventer for the ink, the high-viscosity composition layer 6 is disposed by a high-viscosity composition having a viscosity of 500,000 mP · s, which is based on polybutene, in contact with the interface of the ink 1, and this high-viscosity composition. A movable stopper 5 made of synthetic resin is disposed so as to be partially immersed in the physical layer 6. The movable stopper 5 also plays a role of maintaining the shape of the high viscosity composition layer 6 that is a fluid in the container.
[0010]
As shown in FIG. 2, which is an enlarged view of the portion I in FIG. 1, the movable stopper 5 is formed with an annular convex portion 5 a having an arcuate cross section on the rear end surface. The diameter of the outside air communication hole 4a of the tail plug 4 is set to be equal to or smaller than the inner diameter of the rear end face of the movable plug 5 to form a barrier 4b that can contact the convex portion 5a of the movable plug 5. That is, when the movable stopper 5 is moved backward due to impact, water head pressure when the ball comes off in the case of a ballpoint pen, and the increase in the air present in the ink tank at a high temperature, the convex portion of the movable stopper 5 5a and the barrier 4b are in circumferential contact. Because of the contact between the convex part and the surface, the contact area is extremely small, it is easy to make contact in a circumferential shape, and the contact pressure per unit area during contact increases, so this part is securely sealed The passage between the ink tank and the outside world can be blocked. Therefore, even if the movable stopper 5 moves backward, the ink is prevented from leaking from the outside air circulation hole. Although the annular convex portion 5a in this example has an arc shape in cross section, the cross section may be in the shape of a pyramid or a prism.
[0011]
FIG. 3 shows another example. It is shown as a drawing corresponding to FIG. 2 of the above example. In order to facilitate the assembly process, the tail plug 4 has a vertically symmetric shape, but an annular convex portion 4 c is formed on the tail plug 4. When the movable stopper 5 has moved backward, it contacts the rear end surface of the movable stopper 5 to suppress ink leakage. In addition, you may form the same cyclic | annular convex part in the said rear end surface of the movement stopper 5. FIG.
[0012]
FIG. 4 shows another example. This example is also shown as a drawing corresponding to FIG. 2 of the above example. A recess 5 b is provided on the rear end surface of the movable stopper 5, an elastic body 7 made of ethylene butadiene rubber is disposed in the concave portion 5 b, and a convex portion is formed on the rear end face of the movable stopper 5. Even if the barrier 4b of the tail plug 4 is inclined in the radial direction due to variations in molding dimensions, the axial length of the convex portion made of the elastic body 7 is deformed according to the inclination. 5 can be reliably brought into contact with the barrier 4b, and ink leakage can be suppressed.
[0013]
【The invention's effect】
As described above, according to the present invention, an impact is applied to the writing instrument, or in the case of a ballpoint pen, the ball is detached, ink head pressure is generated, or air is mixed into the ink tank, resulting in volume expansion at a high temperature. As a result, even if the movable stopper is moved backward, the flow of the high-viscosity composition that is the ink backflow preventer is reliably suppressed, so that leakage of the ink is suppressed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example.
FIG. 2 is an enlarged vertical sectional view of a portion I in FIG.
FIG. 3 is a view corresponding to FIG. 2 and showing another example.
FIG. 4 is a view corresponding to FIG. 2 and showing another example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ink 2 Ball-point pen tip 3 Cylinder 4 Tail plug 4a Outside air communication hole 4b Barrier 4c Convex part 5 Mobile stopper 5a Convex part 5b Concave part 6 High viscosity composition 7 Elastic body

Claims (2)

As an ink tank for containing ink in a free state, it has a cylinder that opens at the rear end and communicates with the outside air, and a high-viscosity composition that moves following the ink interface as the ink is consumed in the cylinder A mobile stopper at least partially immersed in the high-viscosity composition is disposed, a barrier capable of contacting the mobile stopper is disposed in the vicinity of the rear end opening of the cylindrical body, and the rear side of the mobile stopper and the outside air are disposed on the barrier. In a writing instrument that opens a communicating vent and closes the flow of the ink and the high-viscosity composition to the cylindrical rear end opening when the barrier and the moving stopper come into contact with each other, the moving stopper comes into contact with the barrier A writing instrument, characterized in that an annular convex portion is provided at a contact portion of the portion and / or the barrier with respect to the movable stopper. The writing instrument according to claim 1, wherein the annular convex portion is formed of an elastic body.

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