JP4042380B2 - Inkjet recording head - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet recording head that records an image or characters on a recording sheet by ejecting ink droplets from a nozzle opening by expansion and contraction of a piezoelectric vibrator.
[0002]
[Prior art]
Ink jet recording heads (hereinafter referred to as “recording heads”) using longitudinally vibrating piezoelectric vibrators are generally formed with a large number of nozzle openings 8 and pressure generating chambers 7 as shown in FIGS. The flow path unit 1 and the head case 2 in which the flow path unit 1 is attached and the piezoelectric vibrator 6 is accommodated are provided.
[0003]
The flow path unit 1 includes a nozzle plate 3 in which nozzle openings 8 are arranged in a direction perpendicular to the paper surface of FIG. 12, and a flow path substrate 4 in which pressure generation chambers 7 communicating with the nozzle openings 8 are arranged. The diaphragm 5 that closes the lower opening of each pressure generating chamber 7 is laminated. The flow path substrate 4 is formed with an ink storage chamber 9 that communicates with each pressure generation chamber 7 via an ink supply path 10 and stores ink supplied to each pressure generation chamber 7. In this example, two rows of nozzle openings 8 and pressure generation chambers 7 are provided.
[0004]
The head case 2 is made of synthetic resin, and the piezoelectric vibrator 6 is accommodated in a space 16 penetrating vertically. The space 16 extends in the direction in which the nozzle openings 8 are arranged, and two spaces 16 are provided corresponding to the rows of the nozzle openings 8. The piezoelectric vibrator 6 has a rear end fixed to a fixed substrate 11 attached to the head case 2 and a front end fixed to an island portion 5 </ b> C on the lower surface of the diaphragm 5.
[0005]
Then, a drive signal generated by a drive circuit (not shown) is input to the piezoelectric vibrator 6 through the flexible circuit board 13 to expand and contract the piezoelectric vibrator 6 in the longitudinal direction. By expanding and contracting the piezoelectric vibrator 6, the island portion 5C of the diaphragm 5 is vibrated to change the pressure in the pressure generating chamber 7, and the ink in the pressure generating chamber 7 is ejected from the nozzle opening 8 as ink droplets. It has become. In the figure, reference numeral 15 denotes an ink supply pipe for supplying ink from an ink cartridge (not shown) to the ink storage chamber 9.
[0006]
On the other hand, in the portion corresponding to the ink storage chamber 9 of the head case 2, pressure fluctuation in the ink storage chamber 9 at the time of ejection is released through a diaphragm 5 made of a polyphenylene sulfide film (hereinafter referred to as “PPS film”). A damper recess 12 is formed. When the damper recess 12 is present as an independent space that does not communicate with the outside, the air in the damper recess 12 passes through the diaphragm 5 made of PPS film and elutes into the ink, and the pressure in the damper recess 12 As a result, the tension of the diaphragm 5 is increased and a sufficient damper effect is not easily obtained. Therefore, by forming an external communication hole 14 that penetrates from the back surface of the damper recess 12 toward the opposite side surface of the head case 2 and communicates the damper recess 12 to the outside, the damper recess as described above is formed. The pressure drop in 12 is prevented.
[0007]
The recording head includes a cleaning unit 17 that forcibly sucks the high-viscosity ink when the ink in the flow path evaporates and the viscosity rises due to being left unused or the like. When the recording head moves to the cleaning position in the non-printing area, the cleaning unit 17 seals the nozzle surface of the recording head as shown in FIG. Let me recover.
[0008]
[Problems to be solved by the invention]
However, in the recording head, since the damper recess 12 is open to the atmosphere, when the recording head is not used for a long time and stored, the moisture in the ink in the ink storage chamber 9 is reduced. Water vapor passes through the diaphragm 5 made of PPS film, and the viscosity of the ink in the ink storage chamber 9 gradually increases.
[0009]
In particular, as shown in FIG. 13, in the case where one damper recess 12 corresponds to one ink storage chamber 9, it is closer to the external communication hole 14 than to a place far from the external communication hole 14. The water in the ink at the location is likely to be released into the atmosphere as water vapor through the diaphragm 5. Therefore, a region with high viscosity (hereinafter referred to as a high viscosity region) is likely to be formed as indicated by reference numeral 19 in FIG. At the same time, the ink other than the high-viscosity region 19 is likely to form a low-viscosity region (hereinafter referred to as a low-viscosity region) as indicated by reference numeral 20. An ink viscosity difference is generated in the ink storage chamber 9. The low viscosity region 20 means “low viscosity” with respect to the high viscosity region 19, and the actual viscosity is close to a normal value.
[0010]
When the ink in the flow path is forcibly sucked using the cleaning unit 17 when the use is started again from the storage state having the viscosity difference as described above, the ink of the low viscosity region 20 has its fluidity. Therefore, the ink is preferentially sucked, and the ink in the high-viscosity region 19 remains as it is and is difficult to be sucked.
[0011]
Therefore, the ink in the flow path corresponding to the high-viscosity region 19 remains almost stagnant, and the clogging of the corresponding flow path may not be recovered and the ink may not be ejected normally, causing a printing failure. . Such a tendency to increase the viscosity is particularly noticeable in pigment-based inks that tend to increase in viscosity. Recently, pigment-based inks are often used to achieve various print quality. Therefore, it has been strongly desired to develop an ink jet recording head that can prevent the increase in the viscosity of the ink due to such long-term storage.
[0012]
13 and 14 show the shape of the upper surface portion of the head case 2, and the ink storage chamber 9, the pressure generating chamber 7, the nozzle opening 8 and the like arranged above the upper surface portion are indicated by a two-dot chain line. It is shown in the figure.
[0013]
On the other hand, as shown in FIG. 14, when a plurality of the ink storage chambers are arranged according to the type of ink, that is, when three chambers such as the ink storage chambers 9A, 9B, and 9C are provided. A high-viscosity region 19 is generated in the ink storage chamber 9B located near the external communication hole 14. The other ink storage chambers 9A and 9C become the low-viscosity region 20, and a viscosity difference is generated between the three ink storage chambers. In particular, depending on the type of ink, there are inks that tend to evaporate moisture in the ink and inks that do not easily evaporate. If these conditions are taken into account, the viscosity difference may be further increased.
[0014]
When the ink in the flow path is forcibly sucked using the cleaning unit 17 when the use is resumed from the storage state having the viscosity difference as described above, the ink storage chamber 9A that is in the low viscosity region 20 is used. , 9C ink is preferentially sucked because its fluidity is better, and the ink in the ink storage chamber 9B in the high viscosity region 19 remains as it is and sucked. It will be hard to be done.
[0015]
Therefore, the ink in the flow path communicating with the ink storage chamber 9B in the high viscosity region 19 remains almost stagnant, and the clogging of these flow paths does not recover, and the ink is normally discharged from the ink storage chamber 9B. There is a possibility that the ink cannot be discharged, which causes a printing defect. Such a tendency to increase the viscosity is particularly noticeable in pigment-based inks that tend to increase in viscosity. Recently, pigment-based inks are often used to achieve various print quality. Therefore, it has been strongly desired to develop an ink jet recording head that can prevent the increase in the viscosity of the ink due to such long-term storage. At the same time, even if the water evaporation amount of each type of ink is the same value, there is a difference in the viscosity between the inks. For example, the viscosity of black tends to be higher than that of the light color. Development of such an ink jet recording head is expected.
[0016]
The present invention has been made in view of such circumstances, and its main object is to provide an ink jet recording head that can reduce the difference in viscosity of ink in the flow path as much as possible in a long-term storage state. .
[0023]
[Means for Solving the Problems]
  A flow path having a number of nozzle openings, a pressure generation chamber communicating with the nozzle openings, an ink storage chamber for storing ink to be supplied to the pressure generation chamber, and a sealing plate for closing the openings of the pressure generation chamber and the ink storage chamber An ink jet recording head comprising a unit, a head case to which the flow path unit is attached, and a pressure generating element that applies pressure fluctuation to the pressure generating chamber, and corresponds to an ink storage chamber of the head case A damper recess for releasing pressure fluctuations in the ink storage chamber is formed in the portion via the sealing plate, and an external communication hole for communicating the damper recess with the outside is formed in the direction opposite to the flow path unit. A plurality of ink storage chambers are provided at positions corresponding to the respective ink storage chambers according to the type of ink that is formed through the case and the ink storage chambers are ejected. The resistance is set to a different value for each ink storage chamber, and the external communication hole allows the water vapor of the ink in each ink storage chamber to reach the damper recess as uniformly as possible between the ink storage chambers in which different types of ink are stored. That it is in led form1The gist of
[0024]
That is, in the ink jet recording head of the present invention, a damper recess for releasing pressure fluctuations in the ink storage chamber is formed through a sealing plate in a portion corresponding to the ink storage chamber of the head case. External communication holes are formed to communicate with the outside, and a plurality of the ink storage chambers are provided according to the type of ink to be ejected. The external communication holes store the water vapor of the ink in each ink storage chamber and store different types of ink. In this mode, the ink is guided to the damper recess as uniformly as possible between the ink storage chambers.
[0025]
Accordingly, the ink viscosity in the plurality of ink storage chambers is almost uniform in all the ink storage chambers. Therefore, when the ink in the flow path is forcibly sucked by the cleaning unit, the suction force is uniform from all the nozzle openings. In addition, it acts on the entire ink storage chamber, and high-viscosity ink is sucked out from all the nozzles at the same time, and thereafter, ink of normal viscosity is ready to be discharged from all the nozzle openings. In addition, as described above, high-viscosity ink is sucked from all the nozzle openings at the same time, which is effective in shortening the sucking time and can reduce the amount of ink consumed for cleaning.
[0026]
In the ink jet recording head of the present invention, when the external communication hole is provided at a position corresponding to each ink storage chamber, a water vapor evaporation channel is provided for each ink storage chamber. The water in the ink evaporates from each ink storage chamber, and the ink viscosity in all of the plurality of ink storage chambers becomes substantially uniform.
[0027]
In the ink jet recording head of the present invention, when the flow resistance of the external communication hole is set to a different value for each corresponding ink storage chamber, the viscosity increase of the ink stored in each ink storage chamber Since the flow resistance of the external communication hole can be selected in accordance with the ratio, it is extremely suitable for making the ink viscosity in each ink storage chamber as uniform as possible.
[0028]
Depending on the type of ink stored in each ink storage chamber, there may be a difference in the rate of increase in viscosity associated with the evaporation characteristics of water. For example, when the viscosity of each ink is measured when a certain amount of water evaporates from each ink, a variation is recognized in the value, the light color ink Y has the lowest viscosity, and the normal color inks C and M The viscosity of the black ink K is higher than that of the ink Y, and the viscosity of the black ink K is higher than that of the inks C and M. Therefore, the ink viscosity in each ink storage chamber can be made uniform by providing each external communication hole with a flow path resistance corresponding to the difference in the viscosity increase rate.
[0029]
In the ink jet recording head of the present invention, the external communication hole having a high flow resistance is provided corresponding to an ink storage chamber in which ink having a high viscosity increase rate is stored, and the external communication hole having a low flow resistance is a viscosity. When the ink storage chambers are provided corresponding to the ink storage chambers in which the ink having a low increase rate is stored, external communication holes having flow path resistances suitable for the ink viscosity increase rates in the ink storage chambers are provided in the ink storage chambers. The ink viscosity for each ink storage chamber becomes as uniform as possible. That is, since it is adapted to the properties of various inks in each ink storage chamber, the object of the present invention can be achieved very reasonably for making the ink viscosity as uniform as possible.
[0030]
In the ink jet recording head of the present invention, when the flow resistance of each of the external communication holes and the viscosity increase rate of the ink in each ink storage chamber are correlated, the above-described correlation is satisfied. By setting the flow path resistance, an external communication hole having a flow path resistance adapted to the rate of increase in the viscosity of the ink in each ink storage chamber can be made to correspond to each ink storage chamber, and the ink viscosity for each ink storage chamber can be increased. Be as uniform as possible.
[0031]
In the ink jet recording head of the present invention, the ink storage chambers are arranged in order from the low viscosity increase rate of the ink stored in the ink storage chamber, and the external communication holes store the ink having a low viscosity increase rate. In this case, the ink having a low viscosity increase rate has an external communication hole that easily evaporates to the atmosphere, and the ink having a high viscosity increase rate has a low communication rate that is difficult to evaporate to the air. Since it is an arrangement environment, the ink viscosity of each ink storage chamber becomes as uniform as possible.
[0032]
In the ink jet type recording head of the present invention, when the sealing plate includes a polyphenylene sulfide film, the water vapor permeability of the film itself, the flow resistance of the external communication hole, the viscosity uniforming function by the arrangement position, etc. In combination, the optimal ink vapor evaporation process is realized.
[0033]
In the ink jet recording head of the present invention, when the ink to be ejected is a pigment-based ink, the viscosity of the pigment-based ink increases sharply due to water evaporation, so it conforms to the viscosity increase rate of the ink in the ink storage chamber. By arranging the external communication holes, the characteristics of the pigment-based ink can be easily dealt with, and the effect of smooth reuse after long-term storage is remarkable and effective.
[0034]
In the ink jet recording head of the present invention, when the pressure generating element is a piezoelectric vibrator, the ink viscosity in the entire ink storage chamber is uniformized in a recording head using a piezoelectric vibrator as the pressure generating chamber. Alternatively, the ink viscosity between the ink storage chambers is made uniform, and reuse after a long-term storage can be performed smoothly.
[0035]
In the ink jet recording head of the present invention, when the piezoelectric vibrator is a longitudinal vibration mode piezoelectric vibrator, the recording head of the type using the longitudinal vibration mode piezoelectric vibrator has, for example, polyphenylene sulfide as a sealing plate. Since many resin films, such as films, that easily permeate water vapor are used, the ink viscosity in the entire ink storage chamber is made uniform, or the ink viscosity between the ink storage chambers is made uniform. The effect of smooth use is remarkable and effective.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail.
[0037]
FIGS. 1 to 5 are diagrams showing a first embodiment of an ink jet recording head according to the present invention. The external communication hole can be formed from the entire area of one ink storage chamber in which water vapor of ink stores one type of ink. This is a case where the shape is guided to the recess for the damper as uniformly as possible. This recording head is basically the same as that shown in FIG. 12, and the same parts will be described below using the same reference numerals. 2 corresponds to the [2]-[2] cross-sectional view of FIG. 3, and FIGS. 3 to 5 are shown in the same manner as FIG. 13 and FIG.
[0038]
The recording head includes a head case 2 in which the piezoelectric vibrator 6 is accommodated, and a flow path unit 1 that is fixed to a unit fixing surface of the head case 2 with an adhesive or the like.
[0039]
In the flow path unit 1, a nozzle plate 3 in which nozzle openings 8 are arranged and a pressure generation chamber 7 that communicates with the nozzle openings 8 are arranged in a line, and each pressure generation chamber 7 is connected to an ink supply path 10. The flow path substrate 4 in which the ink storage chambers 9 for storing the ink to be supplied are formed, and the vibration plates (sealing plates) 5 that close the lower openings of the pressure generation chambers 7 and the ink storage chambers 9 are laminated. Configured.
[0040]
The head case 2 is formed by injection molding a thermosetting resin or a thermoplastic resin, and a piezoelectric vibrator 6 is accommodated as a pressure generating element in a space 16 penetrating vertically so as to correspond to the pressure generating chambers 7. It has become so. The space 16 extends in the direction in which the nozzle openings 8 are arranged, and is provided corresponding to the row of nozzle openings 8. The piezoelectric vibrator 6 is a longitudinal vibration mode piezoelectric vibrator 6, the rear end side of which is fixed to the fixed substrate 11 attached to the head case 2, and the front end surface of the piezoelectric vibrator 6 is fixed to the island portion 5 </ b> C on the lower surface of the diaphragm 5. Has been.
[0041]
Here, the diaphragm 5 is made of a polyphenylene sulfide film (hereinafter referred to as “PPS” film), and is laminated with an island portion 5C made of a stainless steel plate. In the head case 2, a damper recess 12 is formed in a portion corresponding to the ink storage chamber 9 to allow pressure fluctuation generated in the ink storage chamber 9 to escape through the vibration plate 5.
[0042]
If the damper recess 12 exists as an independent space that does not communicate with the outside, the air in the damper recess 12 passes through the diaphragm 5 made of PPS film and is eluted into the ink, and the pressure in the damper recess 12 Is lowered, the tension of the diaphragm 5 is increased, and a sufficient damper effect is not easily obtained. Accordingly, the head case 2 employs a structure that prevents the pressure drop in the damper recess 12 as described above by communicating the damper recess 12 to the outside via the external communication hole 14.
[0043]
Then, a drive signal generated by a drive circuit (not shown) is input to the piezoelectric vibrator 6 through the flexible circuit board 13 to expand and contract the piezoelectric vibrator 6 in the longitudinal direction. By expanding and contracting the piezoelectric vibrator 6, the island portion 5C of the diaphragm 5 is vibrated to change the pressure in the pressure generating chamber 7, and the ink in the pressure generating chamber 7 is ejected from the nozzle opening 8 as ink droplets. It has become. In the figure, 15 is an ink supply pipe for supplying ink from an ink cartridge (not shown) or the like to the ink storage chamber 9, and 15A is an ink supply hole provided at a position corresponding to the ink supply pipe 15 of the diaphragm 5. .
[0044]
The recording head includes a cleaning unit 17 that forcibly sucks the high-viscosity ink when the ink in the flow path evaporates and the viscosity rises due to being left unused or the like. When the recording head moves to the cleaning position in the non-printing area, the cleaning unit 17 seals the nozzle surface of the recording head as shown in FIG. Recover.
[0045]
Three external communication holes 14 are provided at the bottom of the damper recess 12 in FIG. The external communication hole 14 penetrates the head case 2 in the vertical direction as shown in FIG. The position where the external communication hole 14 is opened to the damper recess 12 is such that the high viscosity region 19 in the ink storage chamber 9 formed by each external communication hole 14 is formed in three regions as shown in FIG. Is determined so that the ink viscosity in the entire area of the ink storage chamber 9 is substantially uniform, and one high viscosity region 19 is formed. In the case of FIG. 3, three elongated damper recesses 12 are arranged at equal intervals in the longitudinal direction at the center in the width direction.
[0047]
In the example shown in FIG. 5, external communication holes 14 having different flow path resistances are formed at the bottom of the damper recess 12 according to the shape of the damper recess 12. In the case of FIG. 5, in addition to the equally spaced external communication holes 14 as shown in FIG. 3, external communication holes 14 </ b> A having a small diameter are provided in an auxiliary manner in the vicinity of both ends where the width of the recess 12 for the damper is reduced. Has been placed. By doing so, the corner portion indicated by reference numeral 9A in the ink storage chamber 9 also becomes the high viscosity region 19, and the suction force from the nozzle opening 8 acts uniformly on the corner portion 9A.
[0048]
As described above, when the external communication holes 14 are arranged at equal intervals as shown in FIG. 3, the high viscosity regions 19 formed thereby are distributed over three locations, and these distribution regions are integrated, Eventually, the entire area in the ink storage chamber 9 has a substantially uniform ink viscosity, and when the suction force is applied to the nozzle openings 8, the suction force is transmitted to the entire ink in the ink storage chamber 9 almost uniformly. Good cleaning is done. Therefore, even if the cleaning process is performed after a long period of time, the entire flow path including the nozzle openings 8 is refreshed normally.
[0049]
  In the case of FIG. 5 as well, since the viscosity in the entire area of the ink storage chamber 9 is made uniform as described above, the same advantages as described with reference to FIG. 3 can be obtained. In particular, when the external communication hole 14A is supplementarily added as shown in FIG. 5, the ink viscosity is completely equalized up to the corner 9A, and a more complete cleaning process can be performed.
[0050]
Next, the second embodiment shown in FIGS. 6 and 7 will be described. In this embodiment, a plurality of ink storage chambers are provided according to the type of ink discharged, and the external communication holes 14 store ink vapor in each ink storage chamber 9 and store ink of different types. This is the case where it is guided to the damper recess as uniformly as possible between the chambers 9.
[0051]
In this embodiment, three types of different types of ink are ejected from the nozzle opening 8, and for this purpose, the ink storage chamber 9 includes an ink storage chamber 9 </ b> Y storing a light color ink Y and a normal color. The ink storage chamber 9M stores the ink M, and the ink storage chamber 9C stores other normal color ink C. External communication holes 14 are opened at the bottoms of the damper recesses 12 at locations corresponding to the ink storage chambers 9Y, 9M, and 9C, respectively.
[0052]
Since the external communication holes 14 correspond to the ink storage chambers 9Y, 9M, and 9C, the high viscosity regions 19 are formed in the ink storage chambers 9Y, 9M, and 9C in the respective ink storage chambers. . Therefore, when a cleaning air suction force is applied to all the nozzle openings 8, the suction force uniformly acts on the high-viscosity regions 19 in the three chambers, and good cleaning is performed. Therefore, even if the cleaning process is performed after a long period of time, the entire flow path including the nozzle openings 8 is refreshed normally.
[0053]
Since the ink stored in each of the ink storage chambers 9Y, 9M, and 9C has a different viscosity increase rate, the external corresponding to the ink storage chamber 9C storing the ink having the highest viscosity increase rate. The communication hole 14 is given the largest flow resistance. A flow resistance having a value smaller than the above value is given to the external communication hole 14 corresponding to the ink storage chamber 9M that stores ink having a viscosity increase rate lower than the above value. The flow resistance having the smallest value is given to the external communication hole 14 corresponding to the ink storage chamber 9Y in which the viscosity increase rate is lower than the above value, that is, the lowest ink is stored.
[0054]
In accordance with the principle as described above, the flow resistance value of the external communication hole 14 can be set, for example, by the length of the control passage 14B shown in FIGS. 7 (A), (B), and (C). The figure (A) of the longest control path 14B corresponds to the ink storage chamber 9C having the highest viscosity increase rate, and the figure (B) of the next longest control path 14B shows the viscosity increase rate at the next highest level. The figure (C) of the shortest control passage 14B corresponding to a certain ink storage chamber 9M corresponds to the ink storage chamber 9Y having the lowest viscosity increase rate. In other words, three types of control passages are set in correspondence with each other according to the three-stage viscosity increase rate.
[0055]
The flow path resistance of such a control passage, specifically, the amount of water vapor Q flowing per unit time is set by the following equation. That is,
Q = (W0-W1) / R
W0: Water vapor density at the pipe entrance
W1: Water vapor density at the pipe outlet
R: Channel resistance of the pipeline
R = L / (D × S)
D: Diffusion coefficient of water vapor
S: Pipe cross-sectional area
L: Length of the pipeline
Therefore, the amount of water vapor that evaporates is inversely proportional to the length of the control passage 14B and proportional to the cross-sectional area of the passage.
[0056]
As a method for setting the flow path resistance of the control passage 14B, various other modes can be adopted. For example, what is shown in FIG. 8 is one in which a control pin 21 is inserted into the passage hole of the external communication hole 14, and a spiral groove 22 is formed on the outer peripheral surface of the pin 21. The spiral groove 22 corresponds to the control passage 14B. The length of the control pin 21 is manufactured in three stages, and three types of lengths of the spiral groove 22 are provided. The lengths of the control pins 21 correspond to the ink storage chambers 9Y, 9M, and 9C, and In the meantime, make the ink viscosity as uniform as possible.
[0057]
9 shows a structure in which a breathable sintered alloy 23 is press-fitted into the control passage 14B, and the length of the alloy 23 is divided into three stages a, b, and c.
[0058]
In the embodiment shown in FIG. 10 and FIG. 11, the ink storage chambers 9A, 9B, 9C are arranged in order from the side where the viscosity increase rate of the ink stored in them is low, and the external communication hole 14 is increased in viscosity. It is disposed in the vicinity of the ink storage chamber 9 in which low-rate ink is stored. Since the ink storage chamber 9C having the highest viscosity increase rate is farthest from the external communication hole 14, the ink water vapor from the ink storage chamber 9C has a slow atmospheric diffusion. On the other hand, since the ink storage chamber 9A having the lowest viscosity increase rate is closest to the external communication hole 14, the ink water vapor from the ink storage chamber 9A is actively diffused into the atmosphere.
[0059]
In this way, by setting the distance relationship between each of the ink storage chambers 9A, 9B, 9C and the external communication hole 14, ink water vapor is guided from each ink storage chamber to the damper recess as uniformly as possible. .
[0060]
【The invention's effect】
As described above, according to the ink jet recording head of the first aspect of the present invention, the external communication hole is configured so that the water vapor of the ink is guided from the entire ink storage chamber to the damper recess as uniformly as possible. Yes. Therefore, if normal cleaning operation is performed when starting use again from a long-term storage state, the air suction force transmitted from all the nozzle openings acts uniformly on the entire ink in the ink storage chamber, and normal operation is performed. Cleaning is done. As a result, ink can be properly discharged, and the conventional discharge failure hardly occurs.
[0061]
Furthermore, according to the ink jet recording head of the second aspect of the present invention, a plurality of the ink storage chambers are provided according to the type of ink to be ejected, and the external communication hole has water vapor of the ink in each ink storage chamber. The ink storage chamber is configured to be guided to the damper recess as uniformly as possible between the ink storage chambers in which different kinds of ink are stored. Therefore, when normal cleaning operation is performed when starting to use again from a long-term storage state, the air suction force transmitted from all nozzle openings is uniform over the entire ink in each ink storage chamber in which different types of ink are stored. The normal cleaning is performed. Therefore, even in the case of a plurality of ink storage chambers, ink can be properly discharged, and the conventional discharge failure hardly occurs.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view showing a first embodiment of an ink jet recording head of the present invention.
FIG. 2 is a cross-sectional view of the ink jet recording head.
FIG. 3 is a plan view of a single head case in the ink jet recording head.
FIG. 4 is a plan view showing a modification of the head case.
FIG. 5 is a plan view showing still another modified example of the head case.
FIG. 6 is a plan view showing a second embodiment of the ink jet recording head of the present invention.
FIG. 7 is a cross-sectional view showing the shape of an external communication hole for each ink storage chamber.
FIG. 8 is a cross-sectional view showing an inserted state of a control pin.
FIG. 9 is a cross-sectional view when a flow path resistance of a control passage is selected with a breathable sintered alloy.
FIG. 10 is a plan view of a modification of the second embodiment.
11 is a cross-sectional view taken along line [11]-[11] in FIG.
FIG. 12 is a cross-sectional view showing a conventional ink jet recording head.
FIG. 13 is a plan view showing the conventional head case.
FIG. 14 is a plan view showing another example of the above-described conventional head case.
[Explanation of symbols]
1 Channel unit
2 Head case
3 Nozzle plate
4 Channel board
5 Diaphragm
5C island
6 Piezoelectric vibrator
7 Pressure generation chamber
8 Nozzle opening
9 Ink storage chamber
9A Corner
10 Ink supply path
11 Fixed substrate
12 Recess for damper
13 Flexible circuit boards
14 External communication hole
14A External communication hole
14B Control passage
15 Ink supply tube
15A Ink supply hole
16 spaces
17 Cleaning unit
18 Seal lip
19 High viscosity region
20 Low viscosity region
21 Control pin
22 Spiral groove
23 Breathable sintered alloy

Claims (6)

A flow path having a number of nozzle openings, a pressure generation chamber communicating with the nozzle openings, an ink storage chamber for storing ink to be supplied to the pressure generation chamber, and a sealing plate for closing the openings of the pressure generation chamber and the ink storage chamber An ink jet recording head comprising: a unit; a head case to which the flow path unit is adhered; and a pressure generating element that applies pressure fluctuation to the pressure generating chamber.
A portion of the head case corresponding to the ink storage chamber is formed with a damper recess for releasing pressure fluctuation in the ink storage chamber via the sealing plate, and an external communication hole for communicating the damper recess with the outside. A plurality of the ink storage chambers are provided at positions corresponding to the respective ink storage chambers according to the type of ink that is formed through the head case in a direction opposite to the flow path unit, and the flow path resistance. Is set to a different value for each ink storage chamber, and the external communication holes lead the water vapor of the ink in each ink storage chamber to the recess for the damper as uniformly as possible between the ink storage chambers in which different types of ink are stored. An ink jet recording head characterized by being in a form to be used. External communication holes with high flow resistance are provided corresponding to ink storage chambers in which ink having a high viscosity increase rate is stored, and external communication holes with low flow resistance are stored with ink having a low viscosity increase rate. 2. The ink jet recording head according to claim 1 , wherein the ink jet recording head is provided corresponding to an ink storage chamber. 3. The ink jet recording head according to claim 2 , wherein the flow path resistance of each of the external communication holes is correlated with the rate of increase in the viscosity of the ink in each ink storage chamber. The ink storage chambers are arranged in order from the low viscosity increase rate of the ink stored in the ink storage chambers, and the external communication holes are arranged in the vicinity of the ink storage chamber in which ink having a low viscosity increase rate is stored. 1. An ink jet recording head according to 1. 5. The ink jet recording head according to claim 1, wherein the flow path resistance is set according to a length of a control path of the external communication hole. An ink jet recording head according to claim 5 in which the control pin in the control path of the external communication hole is set to be inserted the channel resistance.

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