JP3724885B2 - Ballpoint pen - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an improvement of a ballpoint pen having an ink backflow prevention mechanism.
[0002]
[Prior art]
In Japanese Utility Model Publication No. 4-52067, the same applicant discloses a mechanism for preventing a backflow of ink in a ballpoint pen provided with a valve chamber in which a ball is loosely fitted. This is provided with a required number of protrusions in the valve chamber in which the ball is loosely fitted with a synthetic resin tip shaft, and a gap formed between the protrusion and the protrusion during writing. The ink is made to flow to the chip through communication. The tip shaft is obtained by injection molding, but the ridges are undercut at the time of mold release, so it is difficult to obtain dimensional accuracy, and it is troublesome to prevent damage to the ridges by inserting balls. In addition, the centrifugal treatment is performed in order to defoam air bubbles that are entrained after ink filling at the time of manufacture, but at that time, there is a disadvantage that the ball bites into the ridge due to the centrifugal force and the ball is fixed. Conventionally, so-called oil-based ballpoint pens using high-viscosity inks and so-called water-based ballpoint pens in which ink is incorporated in fibrous batting and the ink is guided to the ballpoint pen tip through an ink guide core are known. Each of them has some drawbacks, but as a simple disadvantage, oil-based ballpoint pens have the disadvantage that the ink has a high viscosity and therefore has a low dot and writing density. In addition, the water-based ballpoint pen has a drawback in that it requires a member cost due to the use of a batting in which ink is incorporated, and that the consumption of the ink is not known. In addition, in order to improve the respective drawbacks under such circumstances, the ink has a high static viscosity and has a shear thinning viscosity in which the viscosity is lowered by the rotation of the tip ball during writing and the ink flows out. Ballpoint pens that use are also known. However, ballpoint pens that use ink with shear thinning viscosity tend to evaporate the ink, and the amount of ink that flows out is large (to increase the writing density). There are many. Further, since the viscosity of the ink is smaller than that of the oil-based ballpoint pen, the flow resistance with respect to the ink containing tube is small. Therefore, ink leakage (ink flows backward at the rear end of the ink containing tube) easily occurs due to the weight of the ink or impact. For this purpose, it usually prevents the ink from evaporating at the trailing edge of the ink and moves following the consumption of the ink during writing. A follower is provided. However, even if the follower is provided, when writing is performed upward, if the ink on the back surface of the tip ball of the chip runs out, the ink head is added directly, so that a significant backflow occurs. In addition, if the inner diameter or length of the ink containing tube is increased to increase the ink filling amount, there is a problem that the reverse flow phenomenon against impact cannot be supported. When backflow occurs, there is a risk that the inside of the shaft cylinder is stained and ink leaks from a vent hole provided in the shaft cylinder, and the hands and clothes are stained. The ink backflow phenomenon also occurs with oil-based ballpoint pens, but ballpoint pens using shear-thinning inks are prominent.
[0003]
[Problems to be solved by the invention]
An object of the present invention is to improve a ball-point pen using ink having a so-called shear thinning viscosity, in which the viscosity is statically high and the viscosity is reduced by the rotation of the ball at the time of writing and the ink flows out. In addition, the ink backflow prevention mechanism caused by upward writing or impact of the ballpoint pen can improve the disadvantages and disadvantages of the conventional backflow prevention mechanism.
[0004]
[Means for Solving the Problems]
In order to achieve the above object, the ballpoint pen of the present invention has a ball receiving seat at the rear, a valve chamber for loosely fitting the ball valve is provided in the shaft center portion, and a chip fitting hole communicating with the front of the valve chamber is provided. In addition, a so-called joint having a guide hole communicating with the valve chamber at the back of the valve chamber, a tip in the tip fitting hole of the joint, and an ink containing tube fixed to the outer periphery of the shaft, respectively. In a ballpoint pen equipped with an ink backflow prevention mechanism, when an elastic piece is provided at a required position on the outer periphery of the shaft between the tip fitting hole of the joint and the valve chamber, and the ink containing tube is fixed on the outer periphery of the shaft The elastic piece is deformed in the axial direction of the inner hole, and its end becomes a forward contact portion of the ball valve loosely fitted in the valve chamber.
In addition, the ink containing tube has a high viscosity statically, and the viscosity of the tip ball is reduced by the rotation of the tip ball when writing, so that the ink flows out. Is provided with a follower that has the property of preventing ink evaporation and follows the ink as it is consumed.
[0005]
【Example】
The embodiment of the present invention shown in FIGS. 1 to 4 has a press-fitting cylinder part 7 in the first half and a fitting cylinder part 11 in the second half, and the outer side surface of the front press-fitting cylinder part 7 is vertically tapered at a plurality of locations. Ribs 8 are formed, and the ink containing tube 4 is fixed to the fitting cylinder portion 11 to provide the joint 3. A tip 5 holding a tip ball is press-fitted into the tip fitting hole 10 at the tip of the press-fitting cylinder portion 7 from the rear end side.
[0006]
The joint 3 is integrally formed of an elastically deformable synthetic resin. The joint 3 communicates with the chip fitting hole 10 and is provided with a valve chamber 12 on the rear side. A conical ball seat 13 is provided at the rear of the valve chamber 12. Further, a guide hole 13 a communicating with the valve chamber 12 is formed behind the ball receiving seat 13. Further, the valve chamber 12 is cantilevered by drilling a cut window 15c at a required position on the outer peripheral portion of the shaft (fitting tube portion 11) between the tip fitting hole 10 of the joint 3 and the valve chamber 12. The elastic piece 15 is provided. Further, the outer surface of the front end portion of the elastic piece 15 is provided with a protrusion 15b having an appropriate slope on the front surface. As will be described later, the elastic piece 15 is deformed in the axial direction of the inner hole when the ink containing tube 4 is fixed to the outer peripheral portion of the shaft, and the end 15 a of the ball valve 14 is loosely fitted in the valve chamber 12. It becomes the forward contact part.
[0007]
A flange 3a is provided at the rear end of the press-fitting cylinder 7 of the joint 3, and a fitting cylinder 11 is extended behind the flange 3a. A cylindrical ink storage tube 4 is press-fitted and fixed to the outer periphery of the fitting tube portion 11 with its tip abutting against the rear end of the flange portion 3 a, and the inner diameter portion of the ink storage tube 4 communicates with the guide hole 13 a of the joint 3. To do. At that time, the protrusion 15b of the elastic piece 15 is pressed against the inner wall of the ink containing tube 4 and deformed in the axial direction, and the end 15a is in contact with the forward contact portion of the ball valve 14 loosely fitted in the valve chamber in advance. Become. The ink containing tube 4 is filled with an ink 19 having a statically high viscosity and a shear thinning viscosity that allows the ink to flow out by the rotation of the tip ball during writing. In addition, the rear end of the ink 19 is filled with a grease-like follower 20 that prevents the ink from evaporating and moves in contact with the ink surface as the ink is consumed. The ink storage tube 4 is made of, for example, a transparent PP resin molded product that suppresses ink evaporation.
[0008]
Next, a writing part in which the tip 5 and the ink containing tube 4 filled with ink are fixed is inserted into the joint 3 from the tip of the shaft cylinder 1, and the rear edge of the flange 3 a of the joint 3 is inserted in front of the shaft part 6. The base 2 is screwed onto the shaft portion 6 of the shaft tube 1 in a state where the vertical ribs 8 of the press-fit tube portion 7 are brought into contact with the inner step portion 9 of the base 2 in a biting manner. Further, a vent hole communicating with the inner hole portion of the shaft tube 1 is formed at an appropriate position of the shaft tube 1 or communicates with the inside of the shaft tube by a tail plug 18 press-fitted and fixed to the rear end of the shaft tube 1. Vent holes are provided. The shaft tube 1 is made of a transparent resin molded product so that the amount of ink consumed can be understood.
[0009]
[Action]
By the way, in the writing state with the tip 5 facing downward, the ball valve 14 comes into contact with the end 15a of the elastic piece 15, and ink can flow into the chip through a gap formed between the elastic piece and the elastic piece. Made. Although the ink is statically high in viscosity, the viscosity is lowered by the rotation of the tip ball of the chip 5 and the ink flows out, so that writing with a high density is possible without any stickiness. Further, unlike the conventional protrusion, the contact portion formed by the end portion 15a is not subject to deformation due to insertion of a ball valve or restriction due to mold release during molding, so there is no problem in the centrifugal treatment after ink filling. There is no.
[0010]
In the state where the tip 5 is faced upward, the ball valve 14 is positioned at the ball receiving seat 13 of the valve chamber 12 and seals the guide hole 13a. Even if the ink disappears, the head is hung on the ink and does not flow backward. In the embodiment, the tip 5 is press-fitted into the tip fitting hole 10 of the press-fitting cylinder portion 7 of the joint 3 and the vertical rib 8 abuts against the inner step portion 9 of the base 2 so that the tip 5 The base 2 is rattled.
[0011]
【The invention's effect】
The configuration and operation of the ballpoint pen of the present invention are as described above. The valve chamber is provided in the intermediate portion communicating the tip and the ink storage tube, and the ink storage portion and the valve chamber are written upward by a ball valve loosely fitted in the valve chamber. Since the ink is sealed, it is possible to prevent accidents in which the ink flows backward and soils the inside of the shaft cylinder, hands, clothes, and the like. In addition, unlike the conventional example, unlike the undercut ridge that prevents the ball valve from being pulled out, a reliable contact portion is formed. In addition, the problem that the ball bites by centrifugation when defoaming bubbles during ink filling is also solved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing the whole of a ballpoint pen according to an embodiment of the present invention, and is partially shown in a half section.
FIG. 2 is an enlarged vertical cross-sectional view of a front portion of a ballpoint pen that is an embodiment of the present invention, and a part thereof is not shown in cross section.
FIG. 3 is an enlarged longitudinal sectional view of a rear part of a ballpoint pen that is an embodiment of the present invention.
FIG. 4 is a cross-sectional view of a joint used in the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Shaft cylinder 1a Step part 1b Locking groove 1c Step part 1d Locking groove 2 Base 3 Joint 3a collar part 4 Ink storage tube 5 Tip 6 Shaft part 7 Press-fit cylinder part 8 Vertical rib 9 Inner step part 10 Tip fitting hole 11 Fitting cylinder portion 12 Valve chamber 13 Ball receiving seat 13a Guide hole 14 Ball valve 15 Elastic piece 15a End portion 15b Projection portion 15c Cutting window 16 Cap 16a Locking projection portion 16b Locking projection portion 16c End portion 17 Clip 18 Tail plug 19 Ink 20 Follower 21 Follower stick

Claims (2)

A ball receiving seat is provided at the rear, a valve chamber for loosely fitting the ball valve is provided in the shaft center, a chip fitting hole communicating with the front of the valve chamber, and a valve chamber communicating with the valve chamber behind the valve chamber In a ballpoint pen provided with a so-called ink backflow prevention mechanism in which a joint is provided with a guide hole, and a tip is attached to the tip insertion hole of the joint, and an ink storage tube is fixed to the outer periphery of the shaft. An elastic piece is provided at a required location on the outer periphery of the shaft between the tip insertion hole of the joint and the valve chamber , a protrusion is provided on the outer surface of the front end of the elastic piece, and the ink containing tube is fixed to the outer periphery of the shaft. When this occurs, the protrusion of the elastic piece is pressed against the inner wall of the ink containing tube and deformed in the axial direction, so that the end of the elastic piece becomes the forward contact portion of the ball valve loosely fitted in the valve chamber. Ballpoint pen characterized by being configured to. The ink storage tube has a statically high viscosity, and the ink is discharged by the rotation of the tip ball during writing and the ink flows out. The ballpoint pen according to claim 1, wherein the ballpoint pen has a property of preventing ink evaporation and is provided with a follower that follows as the ink is consumed.

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