JP2001071525A - Ink jet recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recording head constituted so as to finely divide an air bubble in a flow channel to make the ejection failure of ink hard to occur. SOLUTION: In an ink jet recording head equipped with a head main body 1 for ejecting ink drops and first and second flow channels 5, 7 guiding the ink supplied from an ink cartridge 2 to the head main body 1, a first filter 9A for almost uniformizing the flow speed distribution of the ink passed through the first and second flow channels 5, 7 and a second filter 9B for removing foreign matter in the ink are provided to the connection part of the first and second flow channels 5, 7 not only to almost uniformize the flow speed distribution of the ink passed through the first and second flow channels 5, 7 but also to finely divide the air bubble remaining in the first flow channels 5 to make the ejection failure of ink hard to occur.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an ink jet recording head for discharging ink supplied from an ink cartridge as ink droplets.

[0002]

2. Description of the Related Art A recording head of an ink jet recording apparatus includes a head body for discharging ink as ink droplets, and an ink cartridge for storing ink to be supplied to the head body. The recording head is provided with an ink supply needle, the ink cartridge is provided with an ink supply port, and the ink is supplied to the head body via the ink supply needle inserted into the ink supply port. ing.

More specifically, as shown in FIG. 8, the recording head is provided with a head body 1 for ejecting ink droplets in response to a print signal on a lower surface of a head holder 10. A cartridge case 12 for accommodating the ink cartridge 2 is provided at an upper portion of the cartridge 10. The above ink cartridge 2
The positioning projection 13 is formed on the lower surface of the ink jet printer 1, and the ink supply port 4 is formed on the lower surface of the positioning projection 13. The opening of the ink supply port 4 is sealed with the film 14 until the ink cartridge 2 is mounted on the recording head.

On the other hand, on the upper surface of the head holder 10,
A recess 11 into which the positioning protrusion 13 is fitted is formed,
The ink supply needle 3 is provided upright in the recess 11. The figure shows a state before the ink cartridge 2 is mounted.

The tip of the ink supply needle 3 is formed in a conical shape so that the film 14 of the ink supply port 4 can be easily pierced. An ink guide hole 6 penetrating vertically is formed in the inclined surface portion at the tip. A first ink flow path 5 communicating with the ink guide hole 6 is formed inside the ink supply needle 3,
0, a second ink flow path 7 for supplying the ink guided into the first ink flow path 5 of the ink supply needle 3 to the head main body 1.
Are formed.

At the entrance of the second ink flow path 7,
A filter 9 for filtering ink supplied from the ink cartridge 2 and trapping foreign matter is provided.

[0007] On the lower surface of the head holder 10, a communication path 8 communicating with the second ink flow path 7 is formed. The ink introduced into the communication path 8 is supplied into the head main body 1 by an ink supply pipe 16 provided in the head main body 1.

In the above-mentioned recording head, when the ink cartridge 2 is mounted, the tip of the ink supply needle 3 is attached to the film 1 for sealing the ink supply port 4 of the ink cartridge 2.
4, the ink supply needle 3 is inserted into the ink supply port 4. Then, the ink in the ink cartridge 2 is supplied to the head main body 1 through the ink guide hole 6 of the ink supply needle 3 and the first ink flow path 5, the second ink flow path 7, and the communication path 8.

The recording head is an ink cartridge 2
The print head is mounted on a carriage (not shown) and prints by ejecting ink droplets from nozzle openings provided in the nozzle plate 15 of the head body 1 while reciprocating in the width direction of the recording paper by the carriage. The consumed ink is supplied from the ink cartridge 2 to the head main body 1 via the first and second ink flow paths 5 and 7.

[0010]

In the above recording head,
Since it is necessary to trap foreign matter having a diameter of 10 μm or more that can flow from the ink cartridge 2 or the like, a metal mesh filter 9 having a fine mesh is used. Therefore, the flow path resistance of the filter 9 is large, and it is necessary to minimize the pressure loss during ink ejection. For this reason, the filter area is made as large as possible, and the first ink flow path 5 in front of the filter 9 is expanded in a trumpet-like downward spread,
The diameter of the second ink flow path 7 after the filter 9 is widened upward.

Due to such a flow path shape, the flow velocity in the central part of the filter 9 is large, but the flow velocity in the peripheral part of the filter 9 becomes small, and a difference occurs in the ink flow velocity when ink is supplied. When such a difference in flow velocity occurs, FIG.
(A) As shown in (b), a bubble 17 grows in a peripheral portion where the flow velocity is small, and a large bubble 1
7 may remain.

As described above, when the large air bubbles 17 remain in the first ink flow path 5, the air bubbles 17 grow more and more when the recording head is left unused for a long time, and when the use is resumed. In this case, the air bubbles 17 pass through the filter 9 and the ink droplets are not normally ejected. In addition, even if the bubbles 17 do not pass through the filter 9, bubbles 17 are generated by the flow of ink at the time of ejection.
, The pressure loss of the filter 9 increases, which may cause printing failure.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide an ink jet type recording head which divides bubbles in a flow path and hardly causes ejection failure.

[0014]

In order to achieve the above object, an ink jet recording head according to the present invention comprises a head body for discharging ink droplets, and a flow path for guiding ink supplied from an ink tank to the head body. An ink jet recording head comprising: a first filter that makes the flow velocity distribution of the ink passing through the flow path nearly uniform; and a second filter that removes foreign matter in the ink. The point is that

That is, the ink jet recording head of the present invention has a flow path for guiding the ink supplied from the ink tank to the head body, and makes the flow rate distribution of the ink passing through the flow path substantially uniform. A first filter and a second filter for removing foreign matter in the ink are provided. For this reason, the flow velocity distribution of the ink passing through the flow channel becomes almost uniform, and the air bubbles remaining in the flow channel are fragmented.
Therefore, even if air bubbles remain in the flow path, the size becomes small, and when the recording head is reused after being left as in the related art, the air bubbles pass through the filter and discharge failure such as "dot missing" occurs. And printing defects due to increased pressure loss due to air bubbles sticking to the filter are less likely to occur.

In the ink jet recording head according to the present invention, when the second filter is provided on the downstream side of the first filter, the first filter functions to trap air bubbles to some extent, and the ejection failure is reduced. It is more difficult to wake up.

In the ink jet recording head according to the present invention, when the diameter of the flow path is increased at a portion where the first and second filters are provided, the area of the first and second filters is reduced. The pressure loss during ink ejection can be reduced even when a fine filter is used as the second filter. Therefore, it is effective for removing small foreign matter. In addition, since the flow velocity distribution tends to be non-uniform in such a flow path having an enlarged diameter, the flow velocity distribution can be effectively made uniform by the first filter.

In the ink jet recording head according to the present invention, the first filter may have a larger opening ratio toward the outer periphery, or the first filter may have a larger opening hole toward the outer periphery. In some cases, the flow velocity on the outer peripheral side of the second filter (in other words, the part closer to the outer wall of the flow path) is increased, and the flow velocity near the center is reduced, so that the flow velocity distribution in the flow path is effectively and uniformly made. You can get closer.

[0019]

Next, embodiments of the present invention will be described in detail.

FIG. 1 is a diagram showing an example of a peripheral structure of a recording apparatus to which an ink jet recording head (hereinafter, referred to as a “recording head”) of the present invention is applied. This apparatus includes a carriage 25 on which an ink cartridge 2 is mounted on an upper part and a head main body 1 is mounted on a lower surface, and a capping device 26 for sealing the head main body 1 and the like.

The carriage 25 is connected to a stepping motor 28 via a timing belt 27, and is guided by a guide bar 29 to reciprocate in the width direction of the recording paper 30. In addition, the carriage 25
Has a surface facing the recording paper 30 (a lower surface in this example).
, A head body 1 is attached. Then, ink is supplied from the ink cartridge 2 to the head body 1 and ink droplets are ejected onto the upper surface of the recording paper 30 while moving the carriage 26 to print images and characters on the recording paper 30 in a dot matrix. I have.

The capping device 26 is provided in a non-printing area within the moving range of the carriage 25, and seals the nozzle opening of the head body 1 during printing suspension so as to prevent drying of the nozzle opening as much as possible. I have.

FIG. 2 is a sectional view showing the structure of the recording head of the present invention. This recording head is basically the same as that shown in FIG. 8, and the same parts will be described below using the same reference numerals. The recording head comprises: a head body 1;
An ink cartridge 2 for storing ink to be supplied to the head main body 1; The recording head is provided with an ink supply needle 3, the ink cartridge 2 is provided with an ink supply port 4, and the head main body 1 is inserted through the ink supply needle 3 inserted into the ink supply port 4.
Is supplied with ink.

More specifically, in the recording head, a head main body 1 for ejecting ink droplets in response to a print signal is attached to a lower surface of a head holder 10, and an ink cartridge 2 is attached to an upper portion of the head holder 10. Is provided. The ink cartridge 2 has a positioning projection 13 formed on the lower surface thereof, and an ink supply port 4 formed on the lower surface of the positioning projection 13. The opening of the ink supply port 4 is sealed with the film 14 until the ink cartridge 2 is mounted on the recording head.

On the other hand, on the upper surface of the head holder 10,
A recess 11 into which the positioning protrusion 13 is fitted is formed,
The ink supply needle 3 is provided upright in the recess 11. The figure shows a state before the ink cartridge 2 is mounted.

The tip of the ink supply needle 3 is formed in a conical shape so that the film 14 of the ink supply port 4 can be easily pierced. An ink guide hole 6 penetrating vertically is formed in the inclined surface portion at the tip. A first ink flow path 5 communicating with the ink guide hole 6 is formed inside the ink supply needle 3,
0, a second ink flow path 7 for supplying the ink guided into the first ink flow path 5 of the ink supply needle 3 to the head main body 1.
Are formed.

The first ink flow path 5 has a trumpet-shaped downwardly expanding diameter, and the second ink flow path 7 has an upwardly expanding diameter. At the joint between the outlet of the first ink flow path 5 and the inlet of the second ink flow path 7, the ink supplied from the ink cartridge 2 and passing through the first and second ink flow paths 5 and 7 is provided. And a second filter 9B for filtering the ink and trapping foreign matter.

As described above, the first and second flow paths 5, 5
Since the diameter of the first and second filters 9A and 9B is increased at the portion where the first and second filters 9A and 9B are provided, the area of the first and second filters 9A and 9B can be increased.
Even when a fine B is used, the pressure loss at the time of ink ejection can be reduced.

The first filter 9A and the second filter 9B
Are provided in close contact with each other such that the second filter is located downstream of the first filter.

The second filter 9B is not particularly limited as long as it can trap foreign matter in the ink, and various kinds of filters can be used. For example, various materials such as glass wool, glass wool membrane, metal mesh, sintered metal, and ceramic sintered body can be used. Among these, a metal mesh having a fine mesh that can reliably trap foreign matter having a diameter of 10 μm or more flowing from the ink cartridge 2 is preferably used.

As the first filter 9A, for example,
As shown in FIG. 3, a filter provided with a circular opening hole 20 in a metal mesh filter can be used. In this example, five opening holes 20 are circumferentially arranged at the periphery of the first filter 9A. As described above, by providing the plurality of opening holes 20 near the periphery of the first filter 9A, the outer peripheral side of the second filter 9B (in other words, the portions near the outer walls of the first and second flow paths 5 and 7). By increasing the flow velocity in step (1) and decreasing the flow velocity near the center, the flow velocity distribution in the flow channel can be effectively made uniform.

On the lower surface of the head holder 10, a communication path 8 communicating with the second ink flow path 7 is formed. The ink introduced into the communication path 8 is supplied into the head main body 1 by an ink supply pipe 16 provided in the head main body 1.

In the above recording head, as shown in FIG.
In a portion where the diameter of the joint between the first ink flow path 5 and the second ink flow path 7 is increased, the flow velocity distribution in the radial direction of the flow path approaches uniform, and the air bubbles 17 remaining in the first flow path 5 are subdivided. Be transformed into Therefore, even if the air bubbles 17 remain in the first flow path, they become small, and when reused after leaving the recording head, the air bubbles 17 pass through the filter and cause ejection such as “dot missing” as in the related art. It is less likely that a defect will occur or that a printing defect due to an increase in pressure loss due to air bubbles 17 sticking to the filter will not occur.

In the recording head, since the second filter 9B is provided downstream of the first filter 9A, the first filter 9A performs a function of trapping air bubbles to some extent, and more discharge failure occurs. Hateful.

FIG. 5A shows a second example of the first filter 9A used in the present invention. In this example, fan-shaped openings 20A and 20B are provided in a metal mesh filter. In this example, four large fan-shaped opening holes 20A are arranged so as to draw a circumference in a portion near the periphery of the first filter 9A, and four small fan-shaped holes are formed in a portion near the center of the first filter 9A. The opening hole 20B is provided so as to describe a circumference. As described above, the first filter 9A is provided with the opening hole 20A which is larger on the outer peripheral side, so that the outer peripheral side of the second filter 9B (in other words, the first and second flow paths 5, 7) are provided.
(The portion close to the outer wall of the flow path), and the flow velocity near the center is reduced, whereby the flow velocity distribution in the flow channel can be effectively made uniform.

FIG. 5B shows a third example of the first filter 9A used in the present invention. In this example, a drop-shaped opening hole 20 is provided in a metal mesh filter. In this example, eight drop-shaped opening holes 20 are radially arranged with the larger opening area facing outward. As described above, the first filter 9A has the opening 20 that is larger on the outer peripheral side, so that the outer peripheral side of the second filter 9B (in other words, the portion close to the outer wall of the first and second flow paths 5 and 7).
By increasing the flow velocity in the flow path and decreasing the flow velocity in the vicinity of the center, the flow velocity distribution in the flow channel can be effectively made uniform.

In the first filter 9A of the first to third examples, the thickness and the opening area (the area ratio of the opening 20 other than the mesh portion) of the first filter 9A are determined by the first and second flow paths 5 and 5. By designing according to the flow path shape of 7 (the degree of diameter expansion), the amount of bubbles 17 remaining in the first ink flow path 5 can be optimized. The shape of the opening 20 is not limited to those shown in the first to third examples, but may be various shapes.

FIG. 6A shows a fourth example of the first filter 9A used in the present invention. This example is an electroformed filter in which a large number of circular openings 20 are formed. In this example, a large number of opening holes 20 are arranged so as to draw concentric circles. The hole diameter of the opening hole 20 located on the outer concentric circle is larger. Thus, the first filter 9A
Is provided with an opening hole 20 that is larger on the outer peripheral side,
Outer peripheral side of second filter 9B (in other words, first and second filters 9B)
By increasing the flow velocity in the portions near the outer walls of the flow paths 5 and 7 and decreasing the flow velocity in the vicinity of the center, the flow velocity distribution in the flow paths can be effectively made uniform.

FIG. 6B shows a fifth example of the first filter 9A used in the present invention. This example is an electroformed filter in which a large number of circular openings 20 are formed. In this example, a large number of opening holes 20 are arranged so as to draw concentric circles. Each opening 20 has the same diameter, but the opening pitch between the openings 20 becomes smaller toward the outer periphery of the first filter 9A, and the opening ratio becomes larger toward the outer periphery. As described above, since the first filter 9A has a larger aperture ratio toward the outer peripheral side, the first filter 9A has an outer peripheral side (in other words, a portion near the outer wall of the first and second flow paths 5 and 7) on the second filter 9B. By increasing the flow velocity in the flow path and decreasing the flow velocity in the vicinity of the center, the flow velocity distribution in the flow channel can be effectively made uniform.

The first filter 9 of the fourth and fifth examples
A, the change in the opening ratio, which becomes larger toward the outer periphery and the thickness of the first filter 9A, is changed by the first and second flow paths 5 and 7.
By designing according to the flow path shape (degree of diameter expansion), the amount of bubbles 17 remaining in the first ink flow path 5 can be optimized. In the fourth and fifth examples,
Although the shape of the opening hole 20 is exemplified as a circular shape, it is not limited to this, and various shapes can be adopted.

The first filter 9 of the fifth example shown in FIG.
In A, the diameter of the opening hole 20 is set to a diameter small enough to trap foreign matter in the ink (for example, 10 μm or less).
In this case, the first filter 9A can make the flow velocity distribution in the flow path nearly uniform and can also remove foreign substances in the ink.
It can also serve as the second filter 9B. That is, although one filter may be used, the present invention is intended to include such an embodiment.

FIG. 7 shows an ink jet recording head according to a second embodiment of the present invention. In this recording head, a space 21 is formed between the first filter 9A and the second filter 9B. Otherwise, it is the same as the first embodiment, and has the same operation and effect.

In each of the above embodiments, an example is shown in which a metal mesh and an electroformed filter are used as the first and second filters 9A and 9B. However, the present invention is not limited to this. Can be used. In this case, the same operation and effect can be obtained.

Further, in each of the above-described embodiments, an example has been shown in which the first filter 9A and the second filter 9B each use one filter, that is, a total of two filters. However, the present invention is not limited to this. 2 or more filters 1A, 2nd
Two or more filters 9B may be provided, and a total of three or more filters may be used. In this case, the same operation and effect can be obtained.

[0045]

As described above, according to the ink jet recording head of the present invention, the flow velocity distribution of the ink passing through the flow path becomes almost uniform, and the air bubbles remaining in the flow path are fragmented. . Therefore, even if bubbles remain in the flow path,
When the recording head is reused after leaving it unattended as in the past, bubbles may pass through the filter, causing ejection failure such as "dot missing", or bubbles may stick to the filter, resulting in pressure loss. And printing defects due to the increase in the size of the image are less likely to occur.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a recording apparatus to which an ink jet recording head of the present invention is applied.

FIG. 2 is a sectional view showing an ink jet recording head of the present invention.

FIG. 3 is a plan view illustrating an example of a first filter.

FIG. 4 is a sectional view showing the operation of the ink jet recording head.

5A and 5B are plan views showing a first filter, wherein FIG. 5A is a second example and FIG. 5B is a third example.

FIGS. 6A and 6B are plan views showing a first filter, wherein FIG. 6A is a fourth example and FIG. 6B is a fifth example.

FIG. 7 is a sectional view showing a second embodiment of the ink jet recording head according to the present invention.

FIG. 8 is a sectional view showing a conventional ink jet recording head.

FIGS. 9A and 9B are cross-sectional views showing the operation of the above-mentioned conventional ink jet recording head, wherein FIG.
Indicates the state after the growth of bubbles.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Head main body 2 Ink cartridge 5 1st flow path 7 2nd flow path 9A 1st filter 9B 2nd filter

Claims (5)

[Claims] 1. An ink jet recording head comprising: a head main body for discharging ink droplets; and a flow channel for guiding ink supplied from an ink tank to the head main body,
An ink jet recording head, wherein the flow path is provided with a first filter for making the flow velocity distribution of the ink passing through the flow path substantially uniform, and a second filter for removing foreign matter in the ink. 2. The ink jet recording head according to claim 1, wherein the second filter is provided downstream of the first filter. 3. The ink jet recording head according to claim 1, wherein the diameter of the flow path is increased at a portion where the first and second filters are provided. 4. The ink jet recording head according to claim 1, wherein the first filter has a larger aperture ratio toward an outer peripheral side. 5. The ink jet recording head according to claim 1, wherein the first filter has a larger opening hole toward an outer periphery.