JP2003063023A - Coloring agent reservoir and image forming device equipped with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of image quality caused by pressure variation in a region pertaining to the same side of the inflow port of a coloring agent. SOLUTION: A filter 25 is arranged so as to divide the region within the housing 20 of an ink reservoir 12 nearly in half. An air port 31 is provided so that the region pertaining to the same side of the inflow port 21 relative to the filter 25 communicates with open air. Thus, the air pressure within the region can be satisfactorily released.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a colorant reservoir having a filter and an image forming apparatus having the same.

[0002]

2. Description of the Related Art In an electrostatic ink jet printer, ink droplets containing pigment particles charged with a predetermined electric charge are ejected from a print head toward a recording medium such as paper by utilizing deflection of an electrostatic field. As a result, there is one that forms an image on a recording medium. Further, in such an electrostatic ink jet printer, it is general that ink is supplied to the print head by a pump arranged between the ink tank storing the ink and the print head.

Here, in the case of a structure in which a pump is directly connected to the print head to supply ink, the amount of ink ejected from the print head fluctuates due to the pulsation of ink flowing out from the pump. The quality of the image formed on the paper may deteriorate. Also, if the pigment particles contained in the ink or dust floating in the ink is larger than the diameter of the printhead ejection hole, the pigment particles or dust clogging the ejection hole of the printhead and the ink is ejected from the printhead. It may not be possible to properly eject. In order to solve such a problem, a technique of providing an ink reservoir having a filter between a print head and a pump is known.

Here, an example of the above-mentioned ink reservoir will be described with reference to FIG. 4, which is a sectional view thereof. Figure 4
The ink reservoir 112 shown in FIG. 2 has a casing 120 having an inlet 121 through which ink flows and an ink supply port 122 for supplying ink to a print head (not shown) on the right bottom surface and the left side surface, and the housing 120. A mesh-shaped filter 125 vertically arranged so as to divide the inner space of the filter into approximately two, and an overflow pipe 128 vertically arranged to overflow a predetermined amount of ink in the space on the right side of the filter 125. It is provided with an air hole 132 provided so as to connect the space on the left side of the housing 120 and the outside air. By using such an ink reservoir 112, fluctuations in the amount of ink ejected from the print head due to pulsation of ink flowing out from the pump can be suppressed to some extent. Further, the ink that has flowed in from the inflow port 121 passes through the filter 125 to open the mesh of the filter 125 (the length of one side of the opening portion in the case of a lattice mesh).
The pigment particles and dust having a diameter equal to or larger than the above are removed and then supplied to the print head. Therefore, it is possible to prevent pigment particles and dust from clogging the ejection holes of the print head. The air holes 132 are
This is for depressurizing the air in the space (left and right spaces) of the housing 120.

[0005]

However, in the electrostatic ink jet printer provided with the ink reservoir 112, when ink adheres to the surface of the upper end portion of the filter 125 (the portion not immersed in the ink liquid), the surface By forming the ink film on the left side, the space on the right side and the space on the left side inside the housing 120 do not communicate with each other. Therefore, the depressurization of air in the space on the right side of the housing 120 is performed by the air holes 132.
Is not sufficiently performed via the ink, and the pressure fluctuation in the right space is easily transmitted to the left space via the ink. As a result, the amount of ink ejected from the print head may fluctuate and the quality of the image formed on the sheet may not be sufficiently suppressed from being deteriorated.

Therefore, the main object of the present invention is to prevent the deterioration of the quality of the image formed by the pressure fluctuation in the region on the same side as the colorant inlet. To provide a reservoir and an image forming apparatus including the reservoir.

[0007]

In order to achieve the above object, a colorant reservoir according to claim 1 is provided with an inflow port into which a colorant flows in, an outflow port from which a colorant flows out, and a colorant into the inflow port. A filter that passes when moving from the outlet to the outlet,
A first air hole provided so that a region belonging to the same side as the inlet and the outside air communicate with the filter;
A second air hole provided so that an area belonging to the same side as the outflow port and the outside air communicate with the filter is provided.

According to the first aspect, the region belonging to the same side of the filter as the inflow port and the outside air are always communicated with each other by the first air hole, and the air in the region is sufficiently depressurized. Be seen. Therefore, the pressure fluctuation in the above area is less likely to be transmitted to the area on the same side as the outflow port with respect to the filter via the coloring agent. Therefore, the quality of the image formed may be deteriorated due to the variation in the amount of the colorant flowing out from the first outlet due to the pressure variation in the region on the same side as the colorant inlet. Suppressed. As a result, stable image reproducibility can be obtained.

According to a second aspect of the present invention, there is provided a colorant reservoir in which the colorant flows in, a first outlet in which the colorant flows out, and the colorant moves from the inflow port to the first outlet. When passing through the filter, in a region that belongs to the same side as the inlet with respect to the filter, at least a part of the colorant that has flowed in from the inlet is substantially near the surface of the filter and the surface of the filter. A second outlet provided at a position where the colorant flows out in a direction parallel to the first outlet, and a colorant exceeding a predetermined amount in a region belonging to the same side of the filter as the first outlet. A third outlet for letting air out, a first air hole provided so that an area belonging to the same side of the filter as the inlet and the outside air communicate with each other, Same as the first outlet A second air hole provided so that the region belonging to the first side communicates with the outside air, and the first outlet in the region belonging to the same side as the first outlet with respect to the filter. The inner peripheral surface of the peripheral portion of the base plate protrudes outward, and the peripheral portion is formed so that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the first outlet. An inner peripheral surface of a peripheral portion of the second outlet in a region on the same side as the second outlet with respect to the filter protrudes outward, and the peripheral portion has an inner peripheral surface thereof. It is characterized in that the area of the portion surrounded by is formed so as to become smaller toward the second outlet.

According to the second aspect, similarly to the first aspect, it is possible to prevent the quality of the formed image from being deteriorated due to the pressure fluctuation in the region on the same side as the colorant inlet. On the other hand, part of the colorant that has flowed into the colorant reservoir from the inlet moves near the surface of the filter substantially parallel to it at a relatively high speed. In addition, the large-sized pigment particles or dust contained in the colorant do not pass through the second filter.
It is discharged to the outside from the outlet of. Therefore, it is possible to prevent the filter particles from being clogged due to the relatively large diameter pigment particles or dust contained in the colorant staying on the filter surface. From this point as well, it is possible to prevent the amount of the colorant flowing out from the first outlet from decreasing, and suppress the deterioration of the quality of the formed image. Furthermore, since a third outlet having a so-called overflow function is provided on the same side as the first outlet with respect to the filter, most of the colorant flowing from the inlet into the colorant reservoir has a high velocity. Will pass through the filter. Therefore, stagnation of the colorant hardly occurs near the filter, and it is possible to prevent the filter from being clogged due to this stagnation.
From this point as well, it is possible to prevent the amount of the colorant flowing out from the first outlet from decreasing, and suppress the deterioration of the quality of the formed image. Further, since the peripheral portion of the first outlet is formed as described above, the pigment particles having a relatively large diameter contained in the colorant that has passed through the filter in the colorant reservoir will not enter the first outlet. The colorant is naturally discharged from the reservoir along the flow of the colorant toward the reservoir, and the stain of the colorant hardly occurs in the reservoir. Therefore, it is possible to prevent the amount of the colorant flowing out from the first outlet due to the stagnation from decreasing. From this point as well, it is possible to prevent the amount of the colorant flowing out from the first outlet from decreasing, and suppress the deterioration of the quality of the formed image. Further, since the peripheral portion of the second outlet is formed as described above, most of large-sized pigment particles and dust contained in the colorant that has flowed into the colorant reservoir from the inlet will filter the filter. It is more likely to be discharged from the second outlet to the outside without passing through. Therefore, it is possible to effectively prevent the filter particles from being clogged due to the relatively large-sized pigment particles or dust contained in the colorant accumulating on the filter surface. From this point as well, it is possible to prevent the amount of the colorant flowing out from the first outlet from decreasing, and suppress the deterioration of the quality of the formed image. That is, according to claim 2, the deterioration of the image quality due to the decrease in the amount of the colorant flowing out from the first outlet is suppressed as in the case of claim 1, and the both surfaces of the filter (upstream side and downstream side) are suppressed. (Both sides), deterioration of image quality due to filter clogging is suppressed.

A third aspect of the present invention is an image forming apparatus including the colorant reservoir described above. According to the third aspect, the image forming apparatus can form a high quality image.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of an electrostatic ink jet printer including an ink reservoir according to an embodiment of the present invention.

First, a schematic structure of an electrostatic ink jet printer having an ink reservoir according to this embodiment will be described with reference to FIG. The electrostatic ink jet printer 1 shown in FIG. 1 includes an ink tank 10 and a pump 1.
1, an ink reservoir 12, a print head 15, and
The pressure control valve 18 is provided. Then, the first circulation circuit including the ink tank 10, the pump 11, the ink reservoir 12, and the print head 15, and the ink tank 10,
Pump 11, ink reservoir 12, and pressure adjustment valve 18
Second circulation circuit including the ink tank 10, the pump 11
And a third circulation circuit including the ink reservoir 12 are connected to each other by piping.
The pipe connecting the ink tank 10 and the pump 11 and the pipe connecting the pump 11 and the ink reservoir 12 are common to all circulation circuits.

The ink tank 10 is for storing the ink 2 used for forming an image. Here, the ink 2 is a pigment particle 2 having a property of being positively charged.
a and a liquid medium 2b in which the pigment particles 2a are dispersed. The pump 11 is for circulating the ink 2 in the first to third circulation circuits. In addition, the ink reservoir 12 prevents the pulsation of the ink 2 caused by the pump 11 from being transmitted to the print head 15, and the filter 25 disposed inside the ink reservoir 12 prevents the pulsation of the ink 2 from flowing into the pigment particles 2a and the ink 2 having a relatively large diameter. This is for removing floating dust. The detailed configuration of the ink reservoir 12 will be described later. The print head 15 is for ejecting the ink 2 onto the paper 5 to form an image. Here, the print head 15 has a nozzle 16 having an injection hole formed so as to extend in the main scanning direction, and a large number of electrodes 17 are arranged in the nozzle 16 along the main scanning direction. ing.

Here, the electrostatic ink jet printer 1
In, the ink 2 stored in the ink tank 10 is
The ink is supplied to the ink reservoir 12 by the pump 11. Part of the ink 2 that has flowed into the ink reservoir 12 from the inflow port 21 (see FIG. 2) moves near the surface of the filter 25 in a direction parallel to the surface of the filter 25, and passes through the outflow port 23 (see FIG. 2). It flows out from the ink reservoir 12, passes through the pressure regulating valve 18, and is returned to the inside of the ink tank 10 (above,
It corresponds to the above-mentioned second circulation circuit). Of the ink 2 that has flowed into the ink reservoir 12, the ink 2 that has passed through the filter 25 is further partially supplied to the print head 15 via the ink supply port 22 (see FIG. 2). Then, of the ink 2 supplied to the print head 15, the ink 2 not ejected from the print head 15
Is returned to the inside of the ink tank 10 (the above-mentioned first
Corresponding to the circulation circuit). Of the ink 2 that has passed through the filter 25, the ink 2 that has not been supplied to the print head 15 flows out of the ink reservoir 12 through the overflow hole 28 (see FIG. 2) and is returned to the ink tank 10 (above). , Corresponding to the above-mentioned third circulation circuit).

Further, the resistance to the ink 2 in the pipe of the second circulation circuit can be changed by the pressure adjusting valve 18. Therefore, by controlling the pressure regulating valve 18, the amount of the ink 2 flowing from the outlet 23 of the ink reservoir 12 to the second circulation circuit and the ink reservoir 12 are controlled.
It is possible to adjust the amount of the ink 2 that flows out of the overflow hole 28 of FIG. Even when the pressure adjusting valve 18 is controlled, the amount of the ink 2 supplied from the ink supply port 22 of the ink reservoir 12 to the print head 15 is kept constant.

From ink reservoir 12 to printhead 1
After the ink 2 is supplied to the electrode 5, a positive pulse voltage having a predetermined peak voltage value and a predetermined pulse voltage width is applied from the controller (not shown) to the electrode 17 arranged in the nozzle 16 of the print head 15. Is applied,
A predetermined amount of the liquid medium 2b in the nozzle 16 and the pigment particles 2a contained therein form an ink droplet 3. The repulsive force between the pigment particles 2a and the electrode 17 having the same polarity causes the ink droplet 3 to be charged from the nozzle 16 to have a negative polarity, or toward the grounded (grounded) paper 5. Is ejected.

The ink droplets 3 ejected from the nozzles 16 of the print head 15 form dots of a predetermined size on the paper 5. Here, the amount of the ink droplet 3 ejected from the nozzle 16 per droplet is determined by the controller 1
It is determined by the pulse voltage width applied to 7. That is, by appropriately changing the pulse voltage width by the controller, the amount of each ink droplet 3 ejected from the nozzle 16 can be controlled. Therefore, it is possible to change the amount of the pigment particles 2a contained in the ink droplets 3 and the size (diameter) of the dots formed on the paper 5, so that a desired image can be formed on the paper 5. it can.

Next, the detailed structure of the ink reservoir according to this embodiment will be described with reference to FIG. Figure 2
FIG. 3 is a sectional view of an ink reservoir included in the inkjet printer shown in FIG. 1.

The ink reservoir 12 has a casing 20 having a substantially rectangular parallelepiped outer shape. The housing 20 has an inlet 21 and an air hole 31 on the upper right side, and an ink supply port 22 on the left bottom side.
However, an outlet port 23 is formed on the right bottom surface, an air hole 32 is formed on the upper left surface, and an overflow hole 28 is formed on the upper left side surface. In addition, the ink reservoir 12 includes a housing 20.
Has a filter 25 inside. The filter 25 is
It is arranged substantially vertically so as to divide the area inside the housing 20 into two substantially equal parts. The filter 25 is made of stainless steel (SUS) wire having a wire diameter of 20 μm and is knitted so as to form a grid-like opening, and the opening is 10 μm to 20 μm. Note that the filter 2
It is preferable that the opening size of 5 is changed in consideration of the diameter of the ejection hole of the print head 15 and the diameter of the pigment particles 2a contained in the ink 2. Therefore, when the ink 2 flowing into the ink reservoir 12 passes through the filter 25, the pigment particles 2a and the dust contained in the ink 2 which are equal to or larger than the openings of the filter 25 and dust are removed.

An inflow port 21 provided on the upper right side of the housing 20.
Is for taking in the ink 2 supplied from the pump 11 into the ink reservoir 12. Further, the air hole 31 provided on the right upper surface is for communicating the region belonging to the same side as the inflow port 21 with respect to the filter 25 (that is, the right side of the internal space of the housing 20) and the outside air. The size and number of the air holes 31 are the same as those of the ink reservoir 1.
The amount can be arbitrarily changed within a range in which a large amount of dust does not enter the inside of the ink container 2 and the large amount of the ink 2 in the ink reservoir 12 does not evaporate.

The ink supply port 22 provided on the left bottom surface of the housing 20 is on the opposite side of the filter 25 from the inflow port 21 (that is, on the left side of the internal space of the housing 20), and the ink supply port The ink 2 flowing out from 22 is supplied to the print head 15. Here, the inner peripheral surface of the peripheral portion 22a of the ink supply port 22 projects downward (toward the outside of the housing 20), and the peripheral portion 22a is formed in a substantially conical shape. That is, the area of the portion surrounded by the inner peripheral surface of the peripheral portion 22 a of the ink supply port 22 becomes smaller toward the ink supply port 22. The inner peripheral surface of the peripheral portion 22a of the ink supply port 22 is inclined approximately 60 degrees with respect to the horizontal plane.

In addition, the outflow port 23 provided on the right bottom surface of the housing 20 is located in the same region as the inflow port 21 with respect to the filter 25 (that is, on the right side of the inner space of the housing 20), and the inflow port 21 is provided. It is provided at a position facing the inflow port 21 so that at least a part of the ink 2 that has flowed into the ink reservoir 12 from the above flows in the vicinity of the surface of the filter 25 in a direction substantially parallel to the surface of the filter 25. here,
The inner peripheral surface of the peripheral portion 23a of the outflow port 23 has the ink supply port 2
Similarly to the second peripheral portion 22a, the peripheral portion 22a projects downward (toward the outside of the housing 20) and is formed in a substantially conical shape. That is, the area of the portion surrounded by the inner peripheral surface of the peripheral portion 23 a of the outflow port 23 becomes smaller toward the outflow port 23. The inner peripheral surface of the peripheral portion 23a of the outflow port 23 is inclined by approximately 60 degrees with respect to the horizontal plane. Therefore, from the inflow port 21 to the ink reservoir 1
The ink 2 that has not passed through the filter 25 out of the ink 2 that has flowed into the nozzle 2 flows out from the outlet 23 in a direction parallel to the surface of the filter 25.

The air hole 32 provided on the upper left side is
This is for communicating the region belonging to the same side as the ink supply port 22 with respect to the filter 25 (that is, the left side of the internal space of the housing 20) and the outside air. The size and the number of the air holes 32 are arbitrarily changed within a range in which a large amount of dust does not enter the ink reservoir 12 from the outside and a large amount of the ink 2 in the ink reservoir 12 does not evaporate. can do. Here, since the air holes 32 are formed, the air in the left side region is sufficiently depressurized, so that the ink 2 easily passes through the filter 25 from the right side region and flows into the left side region. The liquid level height of the ink 2 in the left side region easily rises.

The overflow hole 28 provided above the left side surface of the housing 20 has a so-called overflow function, and is based on the height of the overflow hole 28 from the bottom surface of the housing 20 in the left area. The ink 2 that exceeds the determined predetermined amount flows out from the ink reservoir 12 to the third circulation circuit through the overflow hole 28 and is returned to the ink tank 10.

Next, details of the ink flow in the ink reservoir 12 according to the present embodiment will be described.

The ink 2 supplied to the ink reservoir 12 by the pump 11 flows into the housing 20 through the inflow port 21. The ink 2 that has flowed into the housing 20 is provided on the right bottom surface of the housing 20 so that the outflow port 23 faces the inflow port 21, so that the vicinity of the surface of the filter 25 is in a direction substantially parallel to this ( It moves at a relatively large speed in the thrust direction). Further, the inner peripheral surface of the peripheral portion 23a of the outflow port 23 projects downward and the peripheral portion 23a is formed into a substantially conical shape, so that the pigment particles and the dust contained in the ink 2 having a relatively large diameter are included. Most of the gas is discharged to the outside through the outlet 23. As a result, the relatively large diameter pigment particles 2a and dust that cannot pass through the filter 25
It is possible to suppress the accumulation of ink on the surface of the filter 25 and the formation of accumulated ink. Therefore, according to the present embodiment,
The filter 25 is almost never clogged,
The decrease in the amount of the ink 2 supplied from the ink supply port 22 to the print head 15 is suppressed, and a substantially constant amount of the ink 2 is supplied to the print head 15.

A part of the ink 2 moving in the direction parallel to the surface of the filter 25 passes through the filter 25 and moves to the left side area. Here, as described above, the filter 2
Since the overflow hole 28 is formed on the same side as the ink supply port 22 with respect to No. 5, from the inflow port 21 to the housing 20.
Most of the ink 2 that has flowed into the filter 2 has a large speed.
Pass 5 Therefore, the stagnation of the ink 2 is unlikely to occur near the filter 25, and the stagnation hardly causes the filter 25 to be clogged.
The decrease in the amount of the ink 2 flowing out from the ink supply port 22 is suppressed.

The ink 2 that has passed through the filter 25
Is supplied to the print head 15 from the ink supply port 22. Here, as described above, the inner peripheral surface of the peripheral portion 22a of the ink supply port 22 provided on the bottom surface of the left side region projects downward and the peripheral portion 22a is formed in a substantially conical shape. Since the stagnation of the ink 2 that has passed through the filter 25 hardly occurs in the housing 20, it is possible to prevent the amount of the ink 2 flowing out from the ink supply port 22 from decreasing.

Since the ink 2 supplied to the print head 15 has been passed through the filter 25 in the ink reservoir 12, relatively large pigment particles 2a and dust are removed. Therefore, the print head 15
The large diameter pigment particles 2a and dust are hardly clogged in the injection hole of the nozzle 16.

Further, the air hole 31 allows the right side region and the outside air to communicate with each other at all times, so that the pressure in the air in the right side region is sufficiently released. Therefore, the pressure fluctuation in the right side region is suppressed from vibrating the ink 2 in the ink reservoir 12, and the pressure fluctuation is transmitted via the ink 2 to the left side region where the ink supply port 22 is formed. It gets harder. Therefore, the quality of the image formed may be deteriorated due to the change in the amount of the ink 2 flowing out from the ink supply port 22 due to the pressure fluctuation in the region that belongs to the same side as the ink inlet 21. Suppressed.

As described above, according to the ink reservoir 12 of the present embodiment, the cause of the decrease in the outflow amount of the ink 2 from the ink supply port 22 and the clogging of the filter 25 both on the upstream side and the downstream side of the filter 25. As a result, the amount of the ink 2 flowing out from the ink supply port 22 is reduced and the deterioration of the quality of the printed image due to the clogging of the filter 25 hardly occurs.

The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-mentioned embodiment, and as long as it is stated in the claims,
It is possible to make various design changes. For example, in the above-described embodiment, the air holes 31 and 32 are the housing 2
Although the case where it is provided on the upper surface of 0 is described, the position is not limited to this, and the position can be arbitrarily changed as long as it is provided so as to communicate the right side region or the left side region with the outside air. . That is, it may be provided above the side surface of the housing 20.

Further, in the above-described embodiment, the case where the inner peripheral surface of the peripheral portion 22a of the ink supply port 22 projects downward and the peripheral portion 22a is formed in a substantially conical shape is described. However, the invention is not limited to this, and the inner peripheral surface of the peripheral portion 22a of the ink supply port 22 always protrudes outward, and the peripheral portion 22a of the ink supply port 22 is not limited to this.
The area surrounded by the inner peripheral surface is the ink supply port 22.
It does not need to be formed so that it becomes smaller toward the. That is, the bottom surface of the housing 20 may be flat, and the ink supply port 22 may be provided on the bottom surface. Further, even when formed as described above, the inner peripheral surface of the peripheral portion 22a of the outflow port 22 projects outward, and
Any shape may be used as long as the area of the portion surrounded by the inner peripheral surface of the peripheral portion 22a becomes smaller toward the outlet 22. Further, as shown in FIG. 3, the ink supply port 22 is formed on the outer wall surface of the planar bottom surface of the housing 20a, and the ink supply port is provided between the inner wall surface and the outer wall surface of the bottom surface of the housing 20a. The inner peripheral surface of the peripheral portion 22a of 22 protrudes outward, and the peripheral portion 22a is formed so that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the ink supply port 22. It may be.

In the above embodiment, the outlet 23
Although the case where the outlet is formed has been described, the present invention is not limited to this and the outlet 23 does not necessarily have to be provided. However, in a region where the outflow port 23 belongs to the same side as the inflow port 21 with respect to the filter 25, at least a part of the ink 2 flowing in from the inflow port 21 is substantially in the vicinity of the surface of the filter 25 with the surface of the filter 25. It is effective to prevent the filter 25 from being clogged by providing it in a position where it flows in a parallel direction. Further, even when the outflow port 23 is provided, its position can be arbitrarily changed. Therefore, the inner peripheral surface of the peripheral portion 23a of the outlet 23 does not necessarily protrude toward the outside, and the peripheral portion 23a of the outlet 23 is formed.
Does not need to be formed such that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the outlet 23. That is, the bottom surface of the housing 20 may be flat and the outflow port 23 may be provided on the bottom surface. The outlet 23 is
It does not necessarily have to be provided at a position facing the inflow port 21 (a position in which the extending direction of the straight line connecting the inflow port 21 and the outflow port 23 is parallel to the surface of the filter 25). If it is provided on the bottom surface (area facing the inflow port 21), the position can be arbitrarily changed. Further, in the above-described embodiment, the outlet 23
The case where the inner peripheral surface of the peripheral portion 23a of the above is projected downward and the peripheral portion 23a is formed in a substantially conical shape has been described. If the peripheral surface projects outward, and the peripheral portion 23a is formed such that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the outlet 23, it may have any shape. Good. Also, FIG.
As shown in, the outlet 23 is formed on the outer wall surface of the bottom surface of the housing 20a in a planar shape, and the peripheral portion 23a of the outlet 23 is formed between the inner wall surface and the outer wall surface of the bottom surface of the housing 20a. The inner peripheral surface projects outward and the peripheral portion 23a
May be formed such that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the outflow port 23.

Further, in the above-mentioned embodiment, the case where the rectangular filter 25 is used has been described.
Not limited to this, a filter of any shape such as a circular filter may be used. Even when a circular filter is used, the outflow port 23 is the same as the inflow port 2
It is necessary that at least a part of the ink 2 that has flowed in from 1 flows near the surface of the filter in a range that flows in a direction substantially parallel to the surface of the filter. However, the outflow port 23 faces the inflow port 21 (the straight line connecting the inflow port 21 and the outflow port 23 passes through the center position of the circular filter).
It does not necessarily have to be provided at the position.

Further, in the above-mentioned embodiment, the case where the overflow hole 28 is provided on the side surface of the housing 20 has been described, but the invention is not limited to this, and the overflow hole is not necessarily provided, and the overflow hole is not necessarily provided. Even if it is provided, as long as it has an overflow function similar to that of the embodiment, its position and configuration can be arbitrarily changed. However, it is necessary to provide the overflow hole 28 in a region that belongs to the same side as the ink supply port 22 with respect to the filter 25.
This is effective in suppressing clogging of the filter 25.

Further, in the above-described embodiment, the case where the ink 2 containing the pigment particles 2a is used as the colorant has been described, but the present invention is not limited to this, and the paper is formed by an electrostatic ink jet printer such as liquid toner. Any colorant may be used as long as it can form an image thereon. In addition, the ink supply port 22 and the outflow port 23
The inclination angles of the peripheral portions 22a and 23a of the
Setting the angle to 60 degrees or more is effective in suppressing the amount of ink flowing out from the ink supply port 22 and preventing the filter 25 from being clogged.

Further, in the above-described embodiment, the ink reservoir 12 having the substantially rectangular parallelepiped casing 20 is described, but the present invention is not limited to this, and the ink reservoir having any casing may be used. Good. Further, in the above-described embodiment, the ink reservoir provided in the electrostatic ink jet printer is shown, but the colorant reservoir of the present invention is not limited to the electrostatic ink jet printer,
Any device that can form an image using a colorant can be applied.

[0040]

As described above, according to the first aspect, the region belonging to the same side of the filter as the inflow port and the outside air are always communicated by the first air hole, and the inside of the region The air is sufficiently depressurized. for that reason,
It becomes difficult for pressure fluctuations in the above-mentioned region to be transmitted to the region on the same side as the outflow port with respect to the filter via the coloring agent. Therefore, the quality of the image formed may be deteriorated due to the variation in the amount of the colorant flowing out from the first outlet due to the pressure variation in the region on the same side as the colorant inlet. Suppressed. As a result, stable image reproducibility can be obtained.

According to the second aspect, similarly to the first aspect, it is possible to prevent the quality of the formed image from being deteriorated due to the pressure fluctuation in the region on the same side as the colorant inlet. On the other hand, part of the colorant that has flowed into the colorant reservoir from the inlet moves near the surface of the filter substantially parallel to it at a relatively high speed. In addition, the large-sized pigment particles or dust contained in the colorant do not pass through the second filter.
It is discharged to the outside from the outlet of. Therefore, it is possible to prevent the filter particles from being clogged due to the relatively large diameter pigment particles or dust contained in the colorant staying on the filter surface. Furthermore, the third having a so-called overflow function
Since the outlet of the colorant is provided on the same side as the first outlet with respect to the filter, most of the colorant flowing into the colorant reservoir from the inlet passes through the filter at a high speed. Therefore, stagnation of the colorant hardly occurs near the filter, and it is possible to prevent the filter from being clogged due to this stagnation. Further, since the peripheral portion of the first outlet is formed as described above, the pigment particles having a relatively large diameter contained in the colorant that has passed through the filter in the colorant reservoir will not enter the first outlet. The colorant is naturally discharged from the reservoir along the flow of the colorant toward the reservoir, and the stain of the colorant hardly occurs in the reservoir. Therefore, it is possible to prevent the amount of the colorant flowing out from the first outlet due to the stagnation from decreasing. Further, since the peripheral portion of the second outlet is formed as described above, most of large-sized pigment particles and dust contained in the colorant that has flowed into the colorant reservoir from the inlet will filter the filter. It is more likely to be discharged from the second outlet to the outside without passing through. Therefore, it is possible to effectively prevent the filter particles from being clogged due to the relatively large-sized pigment particles or dust contained in the colorant accumulating on the filter surface. That is, according to the second aspect, deterioration of the image quality due to a decrease in the amount of the colorant flowing out from the first outlet is suppressed as in the first aspect, and at the same time, both surfaces of the filter (upstream side and downstream side) are suppressed. (Both sides), deterioration of image quality due to filter clogging is suppressed.

According to the third aspect, the image forming apparatus can form a high quality image.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an electrostatic ink jet printer including an ink reservoir according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an ink reservoir included in the electrostatic inkjet printer shown in FIG.

FIG. 3 is a diagram showing another example of the configuration of the ink reservoir.

FIG. 4 is a cross-sectional view of a conventional ink reservoir.

[Explanation of symbols]

1 electrostatic inkjet printer 2 ink 2a pigment particles 2b Liquid medium 3 ink droplets 5 sheets 10 ink tank 11 pumps 12 Ink reservoir (colorant reservoir) 15 print head 16 nozzles 17 electrodes 18 Pressure regulating valve 20 housing 21 Inlet 22 Ink supply port (outlet; first outlet) 23 Outlet (second outlet) 25 filters 28 Overflow hole (third outlet) 31 air holes 32 air holes

Claims (3)

[Claims] 1. An inflow port through which a colorant flows in, an outflow port through which a colorant flows out, a filter through which the colorant passes when moving from the inflow port to the outflow port, and a flow path for the filter. A first air hole provided so that an area belonging to the same side as the inlet communicates with the outside air, and an area belonging to the same side as the outlet for the filter communicates with the outside air. A colorant reservoir comprising a second air vent. 2. An inflow port into which the colorant flows, a first outflow port from which the colorant flows out, a filter through which the colorant passes when moving from the inflow port to the first outflow port, In a region on the same side of the filter as the inlet, a position where at least a part of the colorant flowing from the inlet flows near the surface of the filter in a direction substantially parallel to the surface of the filter. Was established in
A second outlet through which the colorant flows out; a third outlet for letting out a colorant exceeding a predetermined amount in a region that belongs to the same side of the filter as the first outlet; A first air hole provided so that a region belonging to the same side as the inlet and the outside air communicate with each other; and a region belonging to the same side as the first outlet with respect to the filter and the outside air. And a second air hole provided so as to communicate with each other, and an inner peripheral surface of a peripheral portion of the first outlet in a region on the same side as the first outlet with respect to the filter. While projecting outward, the peripheral portion is formed such that the area of the portion surrounded by the inner peripheral surface becomes smaller toward the first outlet, and Area belonging to the same side as the second outlet The inner peripheral surface of the peripheral portion of the second outlet is projecting outward, and the area of the portion surrounded by the inner peripheral surface of the peripheral portion becomes smaller toward the second outlet. A colorant reservoir characterized by being formed as follows. 3. An image forming apparatus comprising the colorant reservoir according to claim 1.