JPH1178350A - Writing utensil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a writing utensil, which has a simple structure, the miniaturization of which is easy and which has a high ink drying preventing effect, by a method wherein the pressure of an ink applying to a pen body is controlled stably and the expansion and contraction of the air or the like in an ink storage chamber is compensated. SOLUTION: A pressure equalizing pipe 7, within which a pressure equalizing passage 8 is formed, is inserted in an ink storage chamber 4 so as to communicate the tip of the pressure equalizing pipe 7 with the tip of the ink storage chamber 4 and, at the same time, communicate its tail end part with outside through a reservoir 10 in order to use this pressure equalizing passage 8 as a feeder for compensating the expansion and contraction of the air or the like in the ink storage chamber 4. Further, at writing, the waterhead pressure of the ink developing within the ink storage chamber 4 is compensated through this pressure equalizing passage 8 so as to be equal to the atmospheric pressure. At the same time, by means of this pressure equalizing passage 8 and the reservoir 10, the solvent vapor of the ink is prevented from transpiring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink storage type writing instrument for directly storing liquid ink. More specifically, the present invention relates to a writing implement that can maintain the pressure of ink supplied to a pen body constant, can effectively prevent drying of ink, and has a simple structure and can be easily miniaturized.

[0002]

2. Description of the Related Art In general, when a writing instrument is divided into two types of ink reservoirs, a porous body such as cotton is filled in the ink chamber, and a so-called batting type in which ink is held in the porous body by a capillary force, and a so-called batting type in which the ink is retained. There is a so-called ink storage type writing implement that directly stores liquid ink.

The above batting type has a simple structure, but has a small ink holding amount and supplies ink to a pen body by a capillary force. Therefore, there is a restriction on the flow rate of ink supplied to the pen body. In some cases, such as when writing is performed early, there is a problem that the amount of ink supplied to the pen body is insufficient and handwriting is blurred.

In addition, the above-mentioned ink storage type can store a large amount of ink, and the flow rate of ink supplied to the pen body is not restricted in principle. There is an advantage that such does not occur. However, the ink storage type has a mechanism for compensating for expansion and contraction of air and ink in the ink storage chamber due to a change in temperature, a change in water head pressure due to a change in the posture of a writing instrument, and a mechanism for ink to a pen body. It is necessary to provide a mechanism or the like for controlling the supply flow rate, and the structure becomes complicated. Also, even if such a compensation mechanism is provided, depending on conditions, temperature, pressure,
There is a disadvantage that the pressure and flow rate of the ink supplied to the pen body become unstable due to a change in the posture of the writing implement and the like.

There are various types of ink storage type writing implements. As a typical example, there is one provided with a bellows-shaped feeder used for a conventional so-called fountain pen. In this type, ink is held by a capillary force in a feeder composed of a bellows-like flow path having a small sectional area. When air or the like in the ink storage chamber expands, excess ink is pushed out and held in the feeder, and when contraction occurs in the ink storage chamber, the ink held in the feeder is Is sucked back into the ink reservoir and returned in this way, thereby compensating for expansion and contraction in the ink reservoir to maintain a constant pressure.

As another structure, there is a structure using a slide stopper. In this apparatus, the ink storage chamber has a cylindrical shape and the tail end side communicates with the atmosphere, and a slide stopper that is slidable in the axial direction while maintaining airtightness and liquid tightness is provided therein. The ink and the air in the storage chamber are partitioned. This one is
The slide stopper slides in response to ink expansion, contraction, and ink consumption due to writing, maintaining the ink pressure at a constant pressure approximately equal to atmospheric pressure. Further, in order to control the supply of ink to the pen body, a means such as providing a valve mechanism for opening a valve with a slight differential pressure is adopted between the ink storage chamber and the pen body.

By the way, all of these can compensate for the expansion and contraction of the air and ink in the ink storage chamber, but cannot sufficiently compensate for the change in the water head pressure due to the posture of the writing implement. . That is, when writing, the writing implement is used in a substantially vertical position, so that if the free surface of the ink inside the ink storage chamber and the axial depth to the pen body are, for example, 80 mm, the pen body is 80m
A head pressure corresponding to m is generated. Such a water head pressure is a minute pressure, but depending on the type of the pen body, when such a water head pressure acts, a change occurs in the handwriting and a so-called dripping may occur in which ink is pushed out of the pen body. .

[0008] There are various types of pen bodies described above, and generally used ones include a ball tip in which a ball is rotatably held at the tip of a ball holder and a fiber or the like which is hardened. There is a so-called felt chip made of a porous material. These various types of pens have their respective characteristics, but the important factors common to them include the ink seal pressure and the ink withdrawal pressure.

That is, these pen bodies, for example, hold ink by a gap between the ball and the ball holder in the case of a ball tip, and a gap between the fibers in the case of a felt chip, and hold the ink to perform a sealing action. Is the ink seal pressure. If the pressure difference between the inside and outside of the pen exceeds this ink seal pressure,
For example, when the internal pressure is higher than the ink seal pressure, the ink inside is pushed out through these gaps, causing so-called dripping, and when the internal pressure is lower than the ink seal pressure, the ink in these gaps is sucked,
Air will be sucked into the ink reservoir through this gap.

When the ink in the gap is consumed by writing, a new ink is sucked from the inside of the pen body into the gap. Pressure. Therefore, when the internal pressure is lower than the ink withdrawal pressure, writing cannot be performed. The ink seal pressure and the ink withdrawal pressure differ depending on the type of pen body, but with the same type of pen body, the ink seal pressure and the ink withdrawal pressure are substantially equal.

The above-mentioned ball chip has an ink sealing pressure and ink withdrawal pressure of about 100 mm when the ink is oily ink having a high viscosity. In the case of dry ink, it is only about 20 mm. The felt tip is generally 100 mm to several hundred mm.
High ink seal pressure and ink withdrawal pressure.

The above-mentioned felt chip has a high ink sealing pressure, that is, a high ink holding force due to its own capillary force, so that only a small amount of ink can be transferred to a writing surface having no water absorption, such as a resin film. Can only write "thin" on the writing surface. On the other hand, since the ball chip using the water-based ink or the quick-drying ink has weak ink holding power, it can be written on a non-water-absorbing surface such as a resin film. In particular, when a quick-drying ink is used, the ink transferred to the resin film dries instantly, so that it can be applied to the surface of a water-repellent material such as a polyethylene film which could not be written in the past. Writing is possible. Also, this ball chip
Since the ink attached to the surface of the ball is transferred to the writing surface by the rotation of the ball, there are preferable features such that the outline of the written line is clear and a thin line can be written.

However, a ball chip using such an aqueous or quick-drying ink has a size of 20 mm as described above.
Since there are only ink seal pressures and ink withdrawal pressures of a certain degree, in a writing instrument using the same, it is necessary to stably control the pressure of ink supplied to the ball chip to a pressure substantially equal to the pressure of the outside, that is, the pressure of the atmosphere.

Although the felt chip has a large ink seal pressure and ink withdrawal pressure as described above, if a pressure difference between the inside and outside occurs, the drop does not drop and air is not sucked, but is held in the felt chip. The amount of ink that changes easily. Therefore, if the internal pressure is increased even slightly, the amount of ink contained in the felt chip increases, resulting in a so-called ink rich state, and the handwriting becomes undesirably dark. Conversely, if the internal pressure is reduced even if it is slight, the amount of ink held in the felt chip is reduced, resulting in a so-called ink purer state, and the handwriting becomes undesirably thin. Therefore, it is needless to say that it is preferable to stably control the pressure of the supplied ink even in a writing instrument provided with this felt chip.

However, the above-described feeder mechanism basically has only a function of compensating for expansion and contraction of air and the like in the ink storage chamber and maintaining the pressure in the ink storage chamber at a pressure equal to the atmosphere. It was not possible to compensate for the head pressure of the ink. Also, this feeder
Since it has a bellows-like complicated passage, it is easy for ink to dry and clog inside this passage, and such a problem is particularly prominent when quick-drying ink is used.

Further, in the above-mentioned slide stopper type writing implement, when writing, the head pressure of the ink in the ink storage chamber reaches several tens mm, and the ink acting on the pen body also by the sliding resistance of the slide stopper. Pressure changes. Therefore, even if a valve mechanism that opens the valve with a slight differential pressure as described above is added to this slide stopper type, the pressure of the ink acting on the aqueous ball chip or the like still falls within the range of the ink seal pressure. It is difficult to control accurately.

As described above, in the ink storage type writing implement, the pressure in the ink storage chamber is always kept constant, and the fluctuation of the ink pressure due to the water head pressure of the ink inside during writing is eliminated. It is preferable to always control the pressure of the ink supplied to the pen body to be equal to the external atmospheric pressure and to a constant pressure. However, such a conventional ink pressure compensation mechanism is not always satisfactory. Was.

The writing implement has a so-called disposable type in which all the components are integrated and the entire writing implement is discarded when ink is consumed, and a so-called disposable type in which basic parts such as an ink storage chamber and a pen tip are integrated. There is a so-called refill-type writing implement in which a refill is exchangeably housed in a casing body of a writing implement separate from this, or is housed so as to be able to protrude and retract by a knock mechanism or the like.

This refill has basically the same structure as a disposable writing instrument, but has different conditions from a disposable writing instrument. That is, since this refill is housed in a separate casing main body, the size of the refill is limited, and it is particularly necessary to reduce the diameter. It is difficult to adopt a complicated structure. In addition, since it is housed as a separate body in the casing body of the writing implement, it is not possible to structurally complete the seal with the outside, it is always left open, and it is difficult to prevent the ink from drying. It is. For this reason, most of the conventional refill-type writing implements have a ball-chip type using oil-based ink that has a simple structure and does not dry.

Therefore, when a ball-tip type writing instrument using the above-described water-based ink or quick-drying ink is formed into a refill type, it is difficult to reduce the size of the writing instrument due to the complicated ink supply and pressure adjusting mechanism. In addition, problems such as drying of the ink in a short time occur. Therefore, at present, it has been difficult to put a ball-tip type refill using such an aqueous ink or a quick-drying ink into practical use.

[0021]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and it is possible to control the pressure of ink acting on a pen body to a pressure, and to make the structure simple and compact. It is intended to provide a writing instrument which can easily prevent the drying of the ink and can effectively use a ball tip type refill using an aqueous ink or a quick-drying ink, for example.

[0022]

According to a first aspect of the present invention, there is provided a writing instrument main body, a pen body provided at a tip portion of the main body, and a pen body formed in the main body and communicating with the pen body. And a tubular end which is inserted in the axial direction into the ink storage chamber, the leading end communicates with the distal end of the ink storage chamber, and the tail end communicates with the outside at the tail end side of the main body. And a reservoir formed at the tail end of the main body and communicating with the tail end of the pressure equalizing passage and communicating with the outside.

The inside of the ink reservoir is always in communication with the outside by the above-mentioned pressure equalizing passage. The expansion and contraction of the air and the like in the ink reservoir is compensated for, and the inside thereof is maintained at a pressure equal to the atmospheric pressure. Also, even when the writing instrument is set up at the time of writing, since the pressure equalizing passage communicates with the outside, the pressure in the ink storage chamber at the position of the tip becomes equal to the atmospheric pressure, and the pen body has Only the water head pressure corresponding to the distance from the tip of the pressure equalizing passage to the pen body acts, and the pressure acting on the pen body during writing can be controlled to a constant pressure close to the atmospheric pressure, and stable ink Supply and writing are possible. Further, the structure is simple, the production is easy, and the miniaturization is easy.

The evaporation surface of the ink is only the free surface of the ink in the pressure equalizing passage, and its area is small so that the amount of evaporation is small. Is exchanged, and the solvent vapor evaporates from the tail end side of the pressure equalizing passage only by diffusion by molecular motion. Further, since the tail end side of the pressure equalizing passage communicates with the outside through the reservoir, the solvent vapor diffused from the tail end of the pressure equalizing passage by the above-described diffusion is trapped in the reservoir. Evaporation of the solvent vapor of the ink is further reduced. Therefore, the structure can be simple and small-sized, and the drying of the ink can be effectively prevented, so that a ball-tip refill writing instrument using, for example, an aqueous ink or a quick-drying ink can be realized.

According to a second aspect of the present invention, an outflow prevention pipe projects from the reservoir, and the reservoir communicates with the outside via the outflow prevention pipe. Therefore, even if the ink flows out of the pressure equalizing passage, the ink is stored in the reservoir, and is prevented from flowing out to the outside by the flow-out prevention pipe protruding inside. Also in the outflow prevention pipe, the exchange action between the gas in the reservoir and the outside air is prevented, so that the solvent vapor of the ink diffused into the reservoir from the pressure equalizing passage prevents the outflow. Even in the pipe, the substance evaporates to the outside only by diffusion, and the effect of preventing drying of the ink is further enhanced.

According to a third aspect of the present invention, the cross-sectional shape and the cross-sectional dimension of the pressure equalizing passage are such that the ink that has penetrated therein has a liquid columnar shape in the pressure equalizing passage due to the surface tension of its free surface. And the inside is set to a cross-sectional shape and a cross-sectional dimension that does not cause a gas-liquid exchange action in which the positions of ink and air are exchanged. Therefore, it is possible to prevent ink from flowing out of the pressure equalizing passage into the reservoir.

According to a fourth aspect of the present invention, the ink storage chamber has a substantially cylindrical shape, and the cross-sectional area of the pressure equalizing passage is 1/30 to 1/30 of the cross-sectional area of the ink storage chamber. 1
/ 4. Therefore,
In the case of a normal writing instrument, the ink is held in the form of a liquid column in the pressure equalizing passage, and the pressure equalizing passage can compensate for expansion and contraction of the air and the like in the ink storage chamber due to a change in temperature, and can compensate for the ink. Drying can also be effectively prevented.

According to a fifth aspect of the present invention, there is provided a mechanism for preventing ink from splashing having a bent or maze-shaped passage at the tail end of the pressure equalizing passage. . Therefore, even if a strong impact acts on this writing implement and the ink in the pressure equalizing passage is scattered and scattered,
This ink droplet does not scatter to the reservoir or the outside, and does not stain the surroundings. The bent or maze-like passage has an effect of preventing evaporation of the solvent of the ink.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 to 4 show a first embodiment of the present invention. This is a so-called refill-type writing implement which is exchangeably housed in a separate writing implement casing main body, or is housed so as to be protruded and retracted by a knock mechanism or the like. However, this refill has a basic configuration as a writing instrument, and it is of course possible to form a disposable writing instrument having the same structure. This refill-type writing instrument uses a quick-drying ink using a solvent such as an alcohol-based solvent, and uses a ball tip as a pen body.

This writing instrument has a substantially cylindrical main body 1, a ball tip 2 for the quick-drying ink is provided at a tip of the main body 1, and a tail is provided at a tail end of the main body 1. A stopper 3 is attached. In addition, these main body 1 and tail plug 3
Are formed by injection molding a synthetic resin material. Although not shown in the drawings, this refill-type writing instrument is used by being housed in a casing body of an arbitrary writing instrument.

A substantially cylindrical ink storage chamber 4 is formed in the main body 1, and the ink storage chamber 4 is filled with the quick-drying ink 5. The tip of the ink storage chamber 4 is formed in a tapered shape, and communicates directly with the ball chip 2. The tail end side of the main body 1 is partitioned by a partition member 6.

A pressure equalizing pipe 7 is provided in the center of the ink storage chamber 4 along the axial direction of the ink storage chamber 4, and the pressure equalizing pipe 7 is formed in a pressure equalizing passage 8. I have. The tail end of the pressure equalizing pipe 7 is attached to the partition member 6 so as to penetrate the partition member 6 and communicates with the outside through a hole formed in the tail plug 3. The distal end of the pressure equalizing tube 7 extends to a position near the ball chip 2 at the distal end in the ink storage chamber 4, and communicates with the ink storage chamber 4 at this position.

In this embodiment, the distance between the tip of the pressure equalizing tube 7, that is, the tip of the pressure equalizing passage 8 and the ball chip 2 is set to about 10 mm. It is set shorter than the depth of the head pressure corresponding to the ink seal pressure. In this embodiment, the inner diameter of the ink storage chamber 4 is set to about 6 mm, and the inner diameter of the equalizing pipe 7, that is, the diameter of the equalizing passage 8 is set to about 1.5 mm. Is about 1/16 of the sectional area of the ink storage chamber 4.

Also, on the tail end side of the partition member 6,
A cylindrical reservoir portion 9 is formed, and the inside of the reservoir portion 9 is formed in a reservoir 10. This reservoir 1
Reference numeral 0 indicates that if ink flows out of the pressure equalizing passage 8 in the pressure equalizing tube 7, the ink is held to prevent the ink from flowing out. In addition, the above tail plug 3
Is provided with an outflow prevention pipe 11 protruding inward from a center portion thereof.
0 is in communication with the outside. Therefore, this reservoir 1
When the ink that has flowed out into the inside of the ink storage device has been collected, the ink does not flow out as long as the tip of the flow-out prevention tube 11 is not submerged in the ink, even when the writing instrument is horizontally or inverted.

Next, referring to FIG. 2 to FIG.
The ink pressure compensation action of the writing implement according to the embodiment will be described. FIG. 2 shows a case where the writing instrument has a horizontal posture in a non-writing state. In this case, when the amount of the ink 5 is large, the tip of the pressure equalizing tube 7 is immersed in the ink as shown in FIG. However, since the pressure equalizing passage 8 in the pressure equalizing tube 7 has a relatively small diameter, the ink is held therein as a liquid column 5a due to surface tension.
There is no so-called gas-liquid exchange action in which the positions of ink and air are exchanged within the chamber.

Therefore, in this state, if the air in the ink storage chamber 4 expands due to, for example, a rise in temperature, the ink is pushed out into the equalizing passage 8 by the amount of the expansion, and the ink in the ink storage chamber 4 is expanded. Is maintained at a pressure substantially equal to the atmospheric pressure. When the air in the ink storage chamber 4 contracts, the ink column 5a pushed out into the equalizing passage 8 is pushed back into the ink storage chamber 4, and the pressure in the ink storage chamber 4 is reduced. Is maintained at a pressure equal to the atmospheric pressure. In the above case, the ink in the pressure equalizing passage 8 does not have a gas-liquid exchange action, but only moves in the axial direction in the pressure equalizing passage 8 while maintaining the liquid column 5a. It does not flow out of the pressure passage 8.

FIG. 3 shows a case where the writing instrument is inverted in a non-writing state. Also in this case, as described above, the ink column 5a in the pressure equalizing passage 8 moves in response to the expansion and contraction of the air in the ink storage chamber 4 to compensate for the expansion and contraction, and this ink The inside of the storage chamber 4 is maintained at a pressure equal to the atmospheric pressure.

FIG. 4 shows a case where the writing instrument is set up. Also in this case, similarly to the above, the ink column 5a in the pressure equalizing passage 8 moves up and down in response to the expansion and contraction of the air in the ink storage chamber 4, and these expansions and
The shrinkage is compensated and the pressure in the ink storage chamber 4 is maintained at a pressure equal to the atmospheric pressure.

In the above case, after the air in the ink storage chamber 4 is largely contracted and the liquid column 5a in the pressure equalizing passage 8 moves to the tip of the pressure equalizing passage 8, the pressure equalizing passage 8 From 8, external air enters the ink storage chamber 4 to compensate for shrinkage. After the air in the ink storage chamber 4 is greatly expanded and the liquid column 5a of the ink in the equalizing passage 8 reaches the tail end of the equalizing passage 8, the ink is stored in the reservoir 10. Although the ink flows out, the ink is held in the reservoir 10 without flowing out since the above-mentioned outflow prevention tube 11 is protrudingly provided in the reservoir 10.

When the writing instrument is dropped on the floor or the like, the ink in the pressure equalizing passage 8 may be scattered by the impact and scattered from the tail end of the pressure equalizing passage 8. In this case, the scattered ink is stored in the reservoir 10 and does not flow out.

As described above, the pressure equalizing passage 8 functions as a kind of feeder for compensating expansion or contraction of the air or ink in the ink storage chamber 4 during non-writing. In this case, by appropriately setting the relationship between the cross-sectional area of the pressure equalizing passage 8 and the ink storage chamber 4 and the diameter of the pressure equalizing passage 8, the ink can be stored in the reservoir 10 as described above.
It can be set so that it rarely occurs that the air is pushed out into the ink reservoir 4 or the outside air enters the ink reservoir 4 through the pressure equalizing passage 8.

That is, when the temperature changes from T1 ° C. to T2 ° C., the expansion or contraction rate of air is (T2−
T1) / (273 + T1). Therefore, within a normal temperature range, the expansion or contraction rate of air is about 0.3% with respect to a change in temperature of 1 ° C. Therefore, for example, assuming a temperature change range of ± 30 ° C., the expansion or contraction of the air in the ink storage chamber 4 is about 9%. In this embodiment, the ink storage chamber 4
Since has a cylindrical shape with a substantially constant cross-sectional area in the axial direction, the air in the ink storage chamber 4 expands or contracts by about 9% in the axial direction.

When the entire ink storage chamber 4 is substantially filled with air, that is, assuming that the ink is almost empty, the length of the pressure equalizing passage 8 is equal to the length of the ink storage chamber. Since the cross-sectional area of the equalizing passage 8 is set to 9% of the cross-sectional area of the ink storage chamber, for example, the air in the ink storage chamber 4 expands in the axial direction by 9%. In this case, the liquid column 5a of the ink in the equalizing passage 8 becomes (9/100) × (100/9) = 1, and the liquid column 4a of the ink reaches the full end of the equalizing passage 8. It moves but does not flow out of the reservoir 10. Also,
When the air in the ink storage chamber 4 contracts, the air flows into the ink storage chamber 4 from the pressure equalizing passage 8 to compensate for the contraction of the air.

In the state of using or storing such a writing instrument, the temperature change hardly exceeds ± 30 ° C., and the ink storage chamber 4 is generally filled with ink to some extent. , The volume of air is less than the above assumption. Therefore, in general, if the cross-sectional area of the pressure equalizing passage 8 is set to about 1/10 of the cross-sectional area of the ink storage chamber 4, the ink can flow out from the pressure equalizing passage 8 to the reservoir 10. Sex can be reliably eliminated.

In order to hold the ink as the liquid column 5a in the pressure equalizing passage 8 as described above, the diameter of the pressure equalizing passage 8 may be reduced. Equalizing passage 8 for this
The diameter varies depending on the properties of the ink, such as viscosity, but if the diameter is about 6 mm or less, the ordinary ink can be held in a liquid column shape. However, as described above, in order to reduce the possibility that the liquid column 5a in the pressure equalizing passage 8 is scattered as a droplet when the writing implement is dropped on the floor or the like and an impact is applied, the pressure equalizing passage is required. The inner diameter of 8 is preferably about 3 mm or less.

In the above description, the case where the pressure equalizing passage 8 functions as a feeder during non-writing is described. In this state, only the ink column 5a exists. That is, such a writing instrument is filled with ink at the temperature at the time of writing, that is, at room temperature, and at the time of this manufacturing, only a slight length of the ink column 5a exists in the pressure equalizing passage 8. State. The temperature change as described above is periodic, and always returns to the original room temperature state after the temperature rises or falls. In addition, the ink of such a writing instrument is sufficiently degassed at the time of manufacture, does not release gas in the ink storage chamber 4 after filling, and the volume of the ink decreases with writing, while is there. Therefore, in a normal case, the interior of the pressure equalizing passage 8 is almost empty at the time of writing, and only the short ink column 5a is present at the leading end.

The pressure equalizing passage 8 has an effect of preventing drying of the ink 5, especially of a quick-drying ink. That is, first, the cross-sectional area of the pressure equalizing passage 8 is small and the area of the free surface of the ink column 5a inside the ink is also small, so that the amount of evaporation of the ink solvent from this surface is small. Further, the pressure equalizing passage 8 has a small diameter and is long in the axial direction, and the speed of the gas flow inside the pressure equalizing passage 8 is extremely slow. The Reynolds number of the gas flow in the pressure equalizing passage 8 is extremely small. Value, and the behavior of the gas in this passage is a completely laminar region.

Therefore, in this passage, not only the gas-liquid exchange action as described above does not occur, but also the gas exchange action does not occur. Therefore, there is no gas-gas exchange effect in which the position of the solvent evaporated from the free surface of the ink column 5a on the tip side of the pressure equalizing passage 8 and the position of the air on the tail end side are switched. Therefore, in the pressure equalizing passage 8, the solvent vapor diffuses to the tail end side due to the molecular motion, and near the free surface of the liquid column 5a on the front end side, the solvent vapor has a saturated vapor pressure at that temperature. , A continuous vapor pressure distribution such that the vapor pressure of the solvent vapor continuously decreases toward the tail end. Therefore, the vapor pressure of the solvent vapor at the opening at the tail end of the pressure equalizing passage 8 is reduced, and the amount of the solvent vapor escaping from the opening at the tail end is also reduced.

In view of the above, if the cross-sectional area of the pressure equalizing passage 8 is made small and long, the liquid column 5a
Has a small free surface, and the dissipation by the above-mentioned diffusion is also reduced. However, if the cross-sectional area of the pressure equalizing passage 8 is reduced, the free surface of the ink column 5a in the pressure equalizing passage 8 becomes smaller at the opening of the tail end when the air in the ink reservoir 4 expands. It reaches the vicinity, and the evaporation due to the diffusion increases. In order to effectively prevent the dissipation of the solvent vapor due to the diffusion, at least the free surface of the ink column 5a of the ink in the pressure equalizing passage 8 and the opening at the tail end side of the pressure equalizing passage 8 are required. A diffusion prevention length of about 25 mm is required.

Therefore, when the temperature rises within an expected temperature change range and the ink liquid column 5a moves to the tail end side in the pressure equalizing passage 8, the free surface of the liquid column 5a The cross-sectional area, internal volume, and length of the pressure equalizing passage 8 may be set so that the diffusion prevention length of 25 mm or more is left between the pressure equalizing passage 8 and the tail end thereof.

The above-mentioned temperature change range of ± 30 °
C corresponds to extreme cases, such as when a writing instrument is brought into a warm room from a cold outdoor, or when the writing instrument is left on the dashboard of a car parked in the scorching sun. If a change in temperature occurs, the outflow of ink from the pressure equalizing passage 8 to the reservoir 10 is permitted, and it is sufficient to assume that the range of this temperature change is about ± 10 ° C.

In consideration of the above conditions, the pressure equalizing passage 8 has an inner diameter of 6 mm or less, preferably 3 mm or less, and an internal volume of 3% or more of the internal volume of the ink storage chamber 4 and its contents. What is necessary is just to have a length obtained by adding a diffusion prevention length of 25 mm or more to the remaining portion after subtracting the integral.

In the case of a general writing instrument, the cross-sectional area of the pressure equalizing passage 8 as described above is set within a range of 1/30 to 1/4 of the cross-sectional area of the ink storage chamber 4. For example, the pressure equalizing passage 8 performs a sufficient compensating action against a temperature change or the like, and the diffusion of the solvent vapor of the ink in the pressure equalizing passage 8 can be suppressed to a practically sufficient low level.

Further, since the reservoir 10 is formed at the tail end side of the pressure equalizing passage 8, the solvent vapor of the ink evaporated from the tail end opening of the pressure equalizing passage 8 is introduced into the reservoir. Trapped, the solvent vapor can be dissipated to the outside. Further, since the reservoir 10 and the outside are communicated with each other by the small-diameter and long outflow prevention pipe 11, the inside of the outflow prevention pipe also has the function of preventing the above-mentioned gas-gas exchange action. Since only the dissipation of the solvent vapor due to diffusion occurs, there is a further effect of preventing evaporation.

Next, the operation of the writing implement during writing will be described. At the time of writing, as shown in FIGS. 1 and 4, the writing instrument is written with the ball chip 2 turned upright. In this state, the ink 5 accumulates in the lower part of the ink storage chamber 4 and the air
Move to the top of. In this state, a head pressure equivalent to H1 + H2 normally acts on the ball chip 2. However, the leading end of the pressure equalizing tube 7, that is, the pressure equalizing passage 8 reaches the depth of H1, and the tail end of the pressure equalizing passage 8 communicates with the outside. It should be noted that, as described above, normally, only a very short ink column 5a of ink exists in the pressure equalizing passage 8 during writing. Therefore, the tip of the pressure equalizing passage 8, that is, the portion of the ink 5 at the depth of H1 has a pressure equal to the atmospheric pressure.

As a result, the liquid level of the ink 5 in the ink storage chamber 4 drops slightly, and the air above the ink storage chamber 4 expands to a low pressure corresponding to the head pressure of the ink 5 corresponding to H1. Equilibrate and stabilize in state. In this case,
The ink enters the equalizing passage 8 by an amount corresponding to the decrease in the liquid level of the ink 5, and the depth of the liquid column 5a of the ink in the equalizing passage 8 becomes H3.

In this case, for example, the above H1 is set to 50 m
m, and the length of the air portion in the ink storage chamber 4 in the axial direction is 50 mm, the air in the ink storage chamber 4 has a low pressure corresponding to the head pressure of the 50 mm,
It expands, and the amount of expansion is 1 atmospheric pressure to about 1000 head pressure.
Assuming 0 mm, about 50 × 50/1000 in the axial direction
0 = 0.25 mm, and therefore, the amount of decrease in the liquid level of the ink 5 is 0.25 mm, which is equal to this.

On the other hand, in this embodiment, the pressure equalizing passage 8
Is 1/16 of the cross-sectional area of the ink storage chamber 4, the rise of the liquid column 5a of the ink in the pressure equalizing passage 8 due to the lowering of the liquid level of the ink 5 in the ink storage chamber 4 is 0. 25x
16 = 4 mm. Therefore, in practice, the pressure at the tip of the pressure equalizing passage 8, that is, the pressure at the depth of H1 is:
Although it is higher than the atmospheric pressure by the above-mentioned H3 head pressure of 4 mm, this pressure is extremely small and can be ignored in practice.

Therefore, the head pressure acting on the ball chip 2 is H2 + 4 mm. In this embodiment, since H2 is set to about 10 mm as described above, only the head pressure equivalent to this 14 mm acts on the ball chip 2.
Even when the ink seal pressure is as low as, for example, about 20 mm, ink is not pushed out.

In this embodiment, the tip of the pressure equalizing tube 7 can be brought very close to the ball chip 2, and the length of H2 in FIG. 4 is not limited in principle. For example, if the tip of the pressure equalizing tube 7 is made to have a small diameter and the inner diameter of the ball holder of the ball chip 2 is increased and the tip of the pressure equalizing tube 7 is inserted into the ball holder,
, That is, the tip of the pressure equalizing passage 8 can be brought close to, for example, 1 mm of the ball of the ball chip 2.

As described above, since the pressure acting on the ball chip 2 is very small and is always a substantially constant pressure corresponding to substantially H2, stable writing can be performed. In addition,
When the ink is consumed by writing, the ink level in the ink storage chamber 4 and the pressure equalizing passage 8 decreases, but the amount of ink used in one writing is extremely small.
Changes in the ink level during writing are also negligible.

The air in the ink storage chamber 4 may expand during writing due to heat of the writer's hand or the like. However, the temperature rise in such a case is on the order of several degrees Celsius. For example, even if the temperature rises by 3 degrees Celsius, the expansion of this air is 0.3% × 3 = 0.9%. Even if the length in the axial direction is 50 mm, 50 × 0.9 /
100 = 0.45 mm only, the ink level in the ink storage chamber 4 drops by 0.45 mm, and the height H3 of the liquid column 5a in the pressure equalizing passage 8 rises by 0.45 × 16.
= 7.2 mm, which has almost no effect on writing.
In order to reduce the influence of the temperature rise during writing, the cross-sectional area of the pressure equalizing passage 8 may be set to be large within a range satisfying other conditions.

As described above, the pressure compensating action during non-writing and the pressure adjusting action during writing of the writing implement of this embodiment are stably controlled only by the balance of the pressure of each part. Therefore, there are no parts that are affected by dimensional accuracy, such as movable parts and fine orifices, and no variable elements such as capillary force are used, so high reliability is obtained, and the structure is simple, easy to manufacture, and small. Conversion is also easy.

When the diameter of the writing instrument is reduced and the cross-sectional area of the ink storage chamber 4 is reduced, the cross-sectional area of the pressure equalizing passage 8 is correspondingly reduced. Therefore, in the case of a writing instrument having a generally small diameter, such as a refill-type writing instrument, the cross-sectional area of the equalizing passage 8 becomes smaller, and the effect of preventing the ink from drying becomes greater. Therefore, the structure is suitable for a refill-type writing instrument, in combination with the simple structure as described above.

The present invention is not limited to the first embodiment. As described above, the present invention is not limited to the above-described refill-type writing implement, but is applicable to a disposable-type writing implement, and the pen body is not limited to a ball tip, for example, a felt tip. , Or other things.

FIGS. 5 and 6 show a second embodiment of the present invention, which is a disposable writing instrument using an aqueous or quick-drying ink and a felt tip as a pen body. In this figure, the cap is omitted.

As described above, when the pen body is a felt chip, for example, the ink seal pressure is high, but the amount of ink contained in the felt chip increases due to a change in the pressure in the ink storage chamber. Or, it may decrease and the handwriting may become undesirably dark or thick. Therefore, when a temperature change occurs during non-writing and the air in the ink storage chamber expands, the pressure equalizing passage as described above has the effect of compensating for the pressure. , The amount of ink contained in the image becomes excessive, resulting in a so-called ink-rich state, which tends to cause problems such as undesirably thickened handwriting. On the other hand, since such a felt chip has a high ink sealing pressure and ink drawing pressure, it is not necessary to bring the tip end of the pressure equalizing passage close to the pen body as in the case of the ball chip as described above. Can be added.

In the writing implement according to the second embodiment shown in FIGS. 5 and 6, the ink pressure adjusting mechanism includes a partition member 21 for partitioning the ink storage chamber 4 on the inner surface at the tip end thereof.
The partition member 21 and the felt chip 2a
And a shut-off chamber 23 is formed. Also, an orifice hole 22 having a small cross-sectional area is formed at the center of the partition member 21.
Is formed, and the ink storage chamber 4 and the cutoff chamber 23 communicate with each other through the orifice hole 22. The shut-off chamber 23 is filled with air. The configuration of the second embodiment is the same as that of the first embodiment except for the above points. In the drawing, the same reference numerals are given to portions corresponding to the first embodiment. The description is omitted.

According to the second embodiment, when the writing instrument is placed in a horizontal position during non-writing, for example, a small amount of ink
Accumulates on the peripheral wall below the blocking chamber 23, and the tail end of the felt chip 2a is not in contact with the ink 5b, but is in contact with air. Therefore, in the shutoff chamber 23, the ink in the ink storage chamber 4 is not communicated with the felt chip 2a in a liquid state, but is once shut off by air. Then, even when a small differential pressure is generated during a pressure compensation operation such as expansion and contraction of air in the ink storage chamber 4, the orifice hole 22 of the partition member 21 is formed.
Since the ink is held by the capillary force in the ink, the ink is pushed out into the shut-off chamber 23 by such a small differential pressure, and air or ink is discharged from the shut-off chamber 23 into the ink storage chamber 4. You will not be drawn into.
Therefore, the minute differential pressure does not act in the shut-off chamber 23, and the amount of ink contained in the felt chip 2a can be kept constant.

As shown in FIG. 6, when the writing instrument is set up with the felt tip 2a facing downward during writing, a small amount of ink 5b in the shut-off chamber 23 is placed on the tail end side of the felt tip 2a. The ink that comes into contact with the handwriting is supplied to the felt chip 2a. When the ink 5b in the shut-off chamber 23 is consumed, the shut-off chamber 23
The inside of the orifice hole 2 has a low pressure.
Ink is replenished into the shut-off chamber 23 through 2, and the amount of the ink 5b in the shut-off chamber 23 is kept constant, so that a stable ink supply becomes possible.

FIGS. 7 to 9 show a third embodiment of the present invention.
An embodiment will be described. This has the effect of preventing the liquid column of the ink in the pressure equalizing passage from being scattered as a droplet due to impact or the like, and has the effect of preventing the evaporation of the solvent of the ink. The evaporation prevention mechanism can be omitted.

The third embodiment has a basic structure similar to that of the first embodiment, and includes a reservoir 10 partitioned by a partition member 6 on the tail end side of the main body 1. The pressure equalizing passage 8 in the pressure equalizing pipe 7 is connected to the reservoir 1.
It communicates within 0. A scattering prevention mechanism is provided at the tail end side of the pressure equalizing tube 7, that is, at the end communicating with the reservoir 10.

Reference numeral 31 in the figure denotes a scattering prevention member of the scattering prevention mechanism. The scattering prevention member 31 has a head 32 and a neck 33. The neck 33 is closely fitted in the tail end of the pressure equalizing tube 7. The outer diameter of the head 32 is slightly smaller than the inner diameter of the reservoir 10, and an annular gap is formed between the outer peripheral surface of the head 32 and the inner peripheral surface of the reservoir 10. Have been.

The front side surface of the head 32, that is, the surface facing the partition member 6, is provided with, for example, a radial communication groove 3.
4 are formed. A communication groove 35 is also formed on the peripheral surface of the neck 33 along the axial direction, and these communication grooves 34 and 35 communicate with each other. In the case of this embodiment, the communication groove 35 of the neck 33 has a shape in which the periphery of the neck 33 is cut off in a flat shape.
When the tube 3 is fitted into the pressure equalizing tube 7, a gap or passage having an arcuate cross section is formed between the pressure equalizing tube 7 and the inner peripheral surface of the pressure equalizing tube 7.

A plurality of projections 36 are provided on the surface of the head 32 facing the partition member 6, and these projections 36 come into contact with the partition member 6, and the partition member 6 and the head 32
Is formed such that a gap 37 is formed between them.

In the third embodiment, the pressure equalizing passage 8 in the pressure equalizing pipe 7 is provided with the communication grooves 34, 35 of the scattering prevention member 32.
As described above, the writing instrument is communicated with the reservoir 10 to compensate for expansion and contraction of the air and the like in the ink storage chamber 4 of the writing instrument, thereby always maintaining the inside of the ink storage chamber 4 at atmospheric pressure. , If you put this writing instrument on the writing,
It works to eliminate the ink head pressure.

The communication groove 34 is formed along the radial direction, and the communication path formed by the communication grooves 34 and 35 is bent or maze-shaped in the middle. Therefore, even if the writing implement is dropped on a floor from a high place, a strong impact acts, and even if the ink column 5a of the ink in the pressure equalizing passage 8 is scattered in the form of a splash due to the impact, the ink is not scattered. Does not fly into the reservoir 10.
Therefore, the droplets are prevented from flowing out of the reservoir 10 from the reservoir 10.
Spattering to the outside via 1 is reliably prevented.

Further, since the tail end side of the pressure equalizing passage 8 is communicated with the reservoir 10 through the communication grooves 34 and 35, which are the narrow passages, the communication grooves 34 and 35 communicate with air. There is no gas-exchange effect between the ink and the solvent vapor, and since the passage is narrow, diffusion is small and evaporation of the solvent vapor is sufficiently prevented. In this embodiment,
The length of the reservoir 10 in the axial direction is relatively long, and the length of the outflow prevention tube 11 formed in the tail plug 3 is relatively long. Therefore, there is an effect of sufficiently preventing evaporation of the solvent vapor even in the long outflow prevention pipe 11. Therefore, according to this embodiment, the evaporation of the quick-drying ink can be sufficiently prevented without providing the above-described ink evaporation prevention mechanism.

Further, according to this embodiment, even if the air in the ink storage chamber 4 is excessively expanded and the ink flows into the reservoir 10 as described above, the ink storage chamber 4
When the air inside the container again contracts, the ink flowing into the reservoir 10 can be efficiently returned to the ink storage chamber 4.

That is, a gap 37 is formed between the head 32 of the scattering prevention member 31 and the partition member 6.
The outflowing ink is held in the gap 37 and the communication grooves 34 and 35 by capillary force. Therefore, when the air in the ink storage chamber 4 expands and contracts again with the writing implement horizontal or with the pen body facing downward, all of the ink in the reservoir 10 will have the above-mentioned gap 37 and the communication grooves 34, 35. Is sucked into the pressure equalizing passage 8 through the inside,
The ink is returned into the ink storage chamber 4 without being left. In addition, the air is inflated with this writing instrument turned upside down with the pen body side,
When contracted, the leading end of the pressure equalizing tube 7 protrudes above the liquid surface of the ink, so that the ink is originally supplied to the pressure equalizing passage 8.
Does not flow out into the reservoir 10 through the reservoir, so that no ink remains in the reservoir 10.

Further, in the case of the third embodiment, the passage formed in the scattering prevention member 31 is not limited to the above-mentioned one, but may be bent or maze-shaped so as to prevent scattering of ink droplets. Any shape may be used as long as it is a passage.

The present invention is not limited to the above embodiments. Although the above embodiment describes a writing implement for general character writing, the writing implement of the present invention is also applicable to a whiteboard marker, a paint marker, or a writing implement for other uses, and a pen body. However, the type of ink is not limited.

[0083]

As described above, according to the present invention, at the time of writing, the inside of the tip of the ink storage chamber is adjusted to a pressure substantially equal to the atmospheric pressure by the pressure equalizing passage, and the head pressure acting on the pen body can be arbitrarily reduced. , And can be maintained constant, and stable ink supply and writing can be performed. In addition, the pressure equalizing passage compensates for expansion and contraction of air in the ink storage chamber during non-writing, and maintains the pressure in the ink storage chamber at a pressure substantially equal to the atmospheric pressure. Furthermore, the writing instrument of the present invention has no movable parts such as a delicate valve mechanism and the like, and does not have a part utilizing a capillary force such as a fine orifice, and operates only by the pressure balance of each part. The operation reliability is extremely high, and the pressure of the ink can be controlled stably. Further, this writing instrument has a simple structure, can be formed in a small size, can be easily manufactured, and can reduce the cost.

Further, according to the present invention, since the ink is effectively prevented from drying inside inside by the pressure equalizing passage and the reservoir formed at the tail end thereof, it is possible to use quick drying ink. . In addition, this writing instrument is generally formed to have a small diameter because the smaller the cross-sectional area of the ink storage chamber is, the smaller the cross-sectional area of the equalizing passage is, and the higher the effect of preventing the ink from drying is. There are various effects such as being suitable for a refill type writing instrument.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a refill-type writing instrument according to a first embodiment.

FIG. 2 is a vertical sectional view of the first embodiment in a horizontal posture.

FIG. 3 is a longitudinal sectional view of the first embodiment in an inverted posture.

FIG. 4 is a vertical sectional view of the first embodiment in an upright posture.

FIG. 5 is a vertical sectional view of a tip end portion of a disposable writing instrument according to a second embodiment in a horizontal state.

FIG. 6 is a vertical cross-sectional view of a disposable writing instrument according to a second embodiment in a state in which a distal end portion is set up;

FIG. 7 is a longitudinal sectional view of a writing instrument according to a third embodiment.

FIG. 8 is an enlarged longitudinal sectional view of a main part of a writing instrument according to a third embodiment.

FIG. 9 is an exploded perspective view of a main part of a writing instrument according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body 2 Ball tip 2a Felt tip 3 Tail plug 4 Ink storage chamber 7 Equalizing tube 8 Equalizing passage 10 Reservoir 11 Outflow prevention tube

Claims (5)

[Claims] 1. A writing instrument main body, a pen body provided at a tip end of the main body, an ink storage chamber formed in the main body and communicating with the pen body, and an axial direction inside the ink storage chamber. A tubular pressure equalizing passage which is inserted and whose leading end communicates with the leading end of the ink storage chamber and whose tail end communicates with the outside on the tail end side of the main body, is formed at the tail end of the main body. And a reservoir communicating with the tail end side of the pressure equalizing passage and communicating with the outside. 2. The writing implement according to claim 1, wherein an outflow prevention pipe projects from the reservoir, and the reservoir communicates with the outside via the outflow prevention pipe. 3. The cross-sectional shape and cross-sectional dimensions of the pressure equalizing passage are such that the ink that has penetrated into the inside of the pressure equalizing passage is maintained in the form of a liquid column in the pressure equalizing passage due to the surface tension of its free surface, and the ink, air and 2. The writing implement according to claim 1, wherein the position is set to a cross-sectional shape and a cross-sectional dimension which do not cause a gas-liquid exchange action to be exchanged. 4. The ink reservoir has a substantially cylindrical shape, and the cross-sectional area of the pressure equalizing passage is set to be 1/30 to 1/4 of the cross-sectional area of the ink reservoir. The writing implement according to claim 1, wherein: 5. The writing implement according to claim 1, wherein a tail end of said pressure equalizing passage is provided with a mechanism for preventing ink splash having a bent or maze-shaped passage.