JPH09286100A - Ink jet printing head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more miniaturize a head substrate to reduce the production cost thereof and to avoid the generation of crack inferiority in a vibration plate to the utmost. SOLUTION: In an ink jet printing head equipped with a head substrate 25 having a passage substrate 32 having a plurality of nozzle orifices 34 formed thereto on the surface side thereof and having a plurality of pressure chambers 29 communicating with the nozzle orifices and the ink supply passages 31Y, 31M, 31C communicating with the pressure chambers formed thereto in a depressed state and the vibration plate bonded to the rear surface of the passage substrate 25, the nozzle orifices 34 are linearly arranged in one row or two rows. The pressure chambers 29 are formed on both sides of the row of the nozzle orifices 34 so as to extend parallelly toward the outside of the head substrate 25 at a definite angle with respect to the row of the nozzle orifices and the ink supply passages 31Y, 31M, 31C are formed so as to communicate with the outward ends of a plurality of the adjacent pressure chambers 29 on both sides of the row of the nozzle orifices 34.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head which prints by ejecting ink droplets from a nozzle array toward a recording paper, and more particularly to an ink jet print head classified as a Kaiser type piezoelectric print head.

[0002]

2. Description of the Related Art An example of the structure of a conventional ink jet print head of this type is shown in FIGS. FIG.
Shows a plan view of the head substrate 1. A plurality of nozzle holes 2 are obliquely arranged in two rows in the center of the head substrate 1, and a plurality of pressure chambers 3 communicating with the nozzle holes are radially arranged in the peripheral area of the nozzle hole arrangement area. It is arranged so as to extend. The outer end of each pressure chamber 3 is connected to the ink supply passage 5 through the narrow passage 4. The ink supply passage 5 surrounds the plurality of radially arranged pressure chambers 3 in an annular shape as a whole, but when a color head is constructed, as shown in FIG. , Y (yellow), M (magenta),
It is divided for C (cyan) or B (black) in addition to this. Each ink supply path 5 is connected to an ink tank (not shown) held by the head frame via an ink supply port 6 formed in an appropriate portion of the head substrate.

FIG. 11 shows the head substrate 1 shown in FIG.
2 shows the cross-sectional structure of the device. The head substrate 1 is configured by adhering a vibrating plate 8 made of thin plate glass to the back surface side of a flow path substrate 7 made of photosensitive plate glass. The pressure chamber 3 or the ink supply path 5 connected to the pressure chamber 3 is formed in a concave shape by etching the back surface side of the flow path substrate 7. The nozzle hole 2 is formed so as to penetrate from an appropriate portion of the concave portion forming the pressure chamber 3 to the front surface side of the flow path substrate 7. A piezoelectric element 9 is provided on the back surface side of the vibration plate 8 so as to correspond to each pressure chamber 3. The power supply to each piezoelectric element 9 is performed by using the ITO film formed on the back surface side of the diaphragm 8 as a ground and bringing the individual electrodes formed on the flexible substrate 10 into contact with the surface electrodes of each piezoelectric element 9.

When a voltage is applied to the piezoelectric element 9 corresponding to the selected pressure chamber 3, the vibrating plate 8 is bent in a concave manner due to the deformation of the piezoelectric element 9, and an amount corresponding to a reduction in the volume of the pressure chamber 3 due to the deformation. Ink droplets are ejected from the nozzle hole 2 to the outside. When the piezoelectric element 9 and the diaphragm 8 are restored,
Ink is replenished from the ink supply path 5 to the pressure chamber 3 through the narrowed path 4 to prepare for the next printing operation.

[0005]

In the above ink jet print head, as described above, each pressure chamber 3
Are formed radially and the ink supply passages 5 are annularly arranged so as to surround the radially arranged pressure chambers 3, the head substrate 1 has a relatively large flat portion. Therefore, problems such as cracks are likely to occur in the thin diaphragm 8 attached to the flow path substrate 7.
That is, the flow path substrate 7 made of photosensitive plate glass and the thin diaphragm 8 made of ordinary glass have different coefficients of thermal expansion, and these are integrated by bonding or the like to form the head substrate 1. However, in the inkjet print head having the above-described configuration having a relatively large flat portion, the diaphragm 8 is apt to suffer from cracks due to thermal stress. Further, the flow path substrate 7 is manufactured through an etching process using a photosensitive plate glass. However, in the conventional inkjet print head, the head substrate has a relatively large area, and therefore, one The material cost and processing cost of the head substrate 1 are relatively high.

The present invention was devised under such circumstances, and the head substrate can be further downsized, the manufacturing cost thereof can be reduced, and at the same time, It is an object of the present invention to provide an inkjet print head that can avoid the occurrence of crack defects in the diaphragm as much as possible.

[0007]

DISCLOSURE OF THE INVENTION In order to solve the above problems, the present invention employs the following technical means.

According to the present invention, a plurality of nozzle holes are opened on the front surface side, and a plurality of pressure chambers respectively communicating with the respective nozzle holes or ink supply paths communicating with the respective pressure chambers are recessed on the rear surface side. An ink jet print head comprising: a head substrate having a flow path substrate formed in a striped shape, and a vibrating plate attached to the back surface side of the flow path substrate, wherein the nozzle holes are linearly arranged in one row or two. The pressure chambers are arranged in rows and are formed on both sides of the row of nozzle holes so as to extend parallel to each other toward the outside of the head substrate at a constant angle with respect to the row of nozzle holes. And an ink jet print characterized in that the ink supply path is formed so as to be commonly communicated with the outer ends of a plurality of adjacent pressure chambers on each side of the row of nozzle holes. Head is provided.

In the ink jet print head of the present invention, the plurality of pressure chambers formed on the head substrate are not formed so as to extend radially from the nozzle hole forming region as in the conventional case, but are linear nozzles. It is formed so as to extend toward the outside of the head substrate on both sides of the row at a constant angle with respect to the row of nozzles. Therefore, the formation area of the pressure chambers is basically limited to the length range of the row of nozzle holes, and if the length of the pressure chambers is set to an appropriate length, the same number of nozzle holes and the same arrangement as in the conventional case are provided. Also when forming the head substrate, the area of the head substrate can be made significantly smaller than that of the conventional head substrate. As a result, since the photosensitive plate glass is subjected to the etching process to form the concave pressure chambers, the ink supply paths, etc., the head substrate, which has a high manufacturing cost, can be manufactured more from a certain material. As a result, the manufacturing cost of the head substrate is reduced. Further, since the planar shape of the head substrate can be remarkably miniaturized as compared with the conventional one, it becomes possible to effectively avoid the occurrence of defects such as cracks in the vibration plate due to thermal stress. The strength, life and performance of the head substrate, which can be said to be the heart of the product, are stabilized.

According to the present invention, a plurality of nozzle holes are opened on the front surface side, and a plurality of pressure chambers communicating with the nozzle holes or ink supply paths communicating with the pressure chambers are formed on the back surface side. A flow path substrate formed in a concave shape,
An ink jet print head comprising a head substrate having a vibrating plate attached to the back surface side of the flow path substrate, wherein the nozzle holes are linearly arranged in two rows in a staggered pattern. The pressure chambers corresponding to the respective rows are formed so as to extend outwardly at right angles to the rows of the nozzle holes and extend parallel to each other, and the plurality of nozzle holes and the pressure chambers are the nozzle holes. The ink supply passages are formed so as to be commonly communicated with the outer ends of the pressure chambers of the same group on each side of the row of nozzle holes. An inkjet printhead characterized by:

In a preferred embodiment, the plurality of groups are groups corresponding to Y, M, and C, and each group has two ink supply paths on both sides of the row of nozzle holes on the head substrate. Has been formed.

According to the above structure, the plurality of pressure chambers extend from the nozzle holes classified into the same group to both sides of the row of nozzle holes, and further, to the outer end of each pressure chamber on both sides of the row of nozzle holes. Two ink supply paths that are commonly communicated
It will be formed in some places. Therefore, each ink supply path is short and narrow in width as compared with the conventional one in which the ink supply path is laid out in an annular shape. for that reason,
Since the formation area of the ink supply path can be saved accordingly, the planar shape of the head substrate can be further downsized. Further, since it becomes possible to narrow the ink supply path, it is possible to more effectively avoid the problem that cracks are generated in the diaphragm due to thermal stress.

In a preferred embodiment, a flow path plate is disposed on the back surface side of the head substrate, and the flow path plate is provided from each of the Y, M, and C ink supply ports on the back surface side. It is configured to distribute the supplied ink to each of the two ink supply paths of the head substrate.

According to this structure, when an ink tank for storing Y, M, and C colors is used as the ink tank to be mounted on the main frame, each of the ink tanks of the respective colors has one ejection port. Even at the location, the ink of each color can be supplied to the ink supply paths at two locations on the head substrate without any problem. Moreover, since the flow path plate is laminated on the back surface side of the head substrate, the flow path plate does not increase the size of the head substrate or the head frame for mounting the flow path plate, and the inkjet print head is downsized. Does not interfere with.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of an ink jet print head 20 according to the present invention will be specifically described below with reference to the drawings.

This ink jet print head 20
Is classified into a Kaiser type piezoelectric print head, and as shown in FIGS. 1 and 2, a box-shaped main frame 21 and this main frame 21.
Head frames 22, 2 mounted on the front of the vehicle
3 is provided. An ink cartridge 23 (FIG. 5) is mounted inside the box-shaped portion of the main frame 21. In the present embodiment, one of the two head frames 22 provided on the front surface of the main frame 21 on the left and right is for color printing, and the other is for monochrome printing.

The head frame 22 is in the form of a box having a rectangular stepped opening window 24 that is inclined at the front, and a head substrate 25 is provided in the stepped opening window 24, and a head substrate 22 is provided inside the head frame 22. The ink supply plates 26 and 27 for supplying the ink from the ink cartridge 23 to the head substrate 25 supply power to the head substrate 25 between the head substrate 25 and the ink supply plates 26 and 27. The flexible boards 28 are attached respectively. Hereinafter, these will be described in detail.

4 to 8 show the head substrate 25.
The composition of is shown. The head substrate 25 has a plurality of pressure chambers 29 or an ink supply path 3 communicating with each pressure chamber 29 by etching on the back surface side of the photosensitive plate glass.
1 _Y , 31 _M , 31 _C are formed in a concave shape,
A flow path substrate 32 having nozzle holes penetrating from the appropriate portions of the pressure chambers 29 to the front surface side is provided, and a thin glass vibrating plate 33 attached to the back surface side of the flow path substrate 32. It is configured.

As shown in FIG. 4, the head substrate 25 has a rectangular planar shape so that it can be accommodated in the stepped opening window 24 of the head frame 22, and its longitudinal center line. The plurality of nozzle holes 34 are arranged in a zigzag pattern in two rows so as to be substantially aligned with. However,
As described above, since the head frame 22 is inclined with respect to the scanning direction of the main frame 21 (indicated by the arrow A in the drawing), the nozzle hole 3 of the head substrate 25 is formed.
The rows 4 are inclined at a predetermined angle with respect to the scanning direction A of the main frame 21.

As shown in FIG. 5 and FIG. 7, each pressure chamber 29 extends from each nozzle hole 34 in a direction orthogonal to the row of the nozzle holes 34 in the front view of the head substrate 25. It extends toward the outside of the substrate 25. The outer end of each pressure chamber 29 is connected to the ink supply passages 31 _Y , 31 _M , and 31 _C via a narrow passage 30. As described above, the pressure chambers 29 or the ink supply passages 31 _Y , 31 _M , and 31 _C are connected to the flow path substrate 32.
As described above, the openings are formed in the concave shape on the back surface side of the above, and the openings of these concave portions are closed by the diaphragm 33.

The ink jet print head 20 shown in the figure is for color printing, and has the nozzle holes 3
4 and corresponding pressure chambers 29 are grouped into three groups corresponding to three primary colors Y (yellow), M (magenta), and C (cyan) for color printing. That is, the head substrate 25 is divided into groups for Y, M, and C in the longitudinal direction from the end. Then, on both sides of the row of the nozzle holes 34, the pressure chambers belonging to the same group are commonly communicated with the ink supply passages 31 _Y , 31 _M and 31 _C.
Therefore, in the case of the embodiment shown in the drawing, the ink supply passages 31 _Y , 31 _M , and 31 _C are formed in three places on each side of the head substrate in the width direction, and six places in total, and Y, M, and C head substrate 2 for each color
Two ink supply passages are formed on both sides of the width direction 5 of the ink.

Each of the ink supply paths 31 _Y , 31 _M , 31
_C has a width sufficient and sufficient for supplying ink to a predetermined number of pressure chambers 29 belonging to the group in charge without any inconvenience, and at a suitable position thereof, extends outward in the width direction of the head substrate. The extending portion 35 is formed. An ink supply port 36 is opened in a portion of the vibration plate 33 that covers the extending portion 35, as shown in FIGS. 6 and 8.

A ground electrode film (not shown) made of an ITO film is formed on the back surface of the head substrate 25, that is, the back surface of the vibration plate 33, and the pressure chambers 29 and the pressure chambers 29 are formed on the ground electrode film. The piezoelectric element 37 is attached in a corresponding manner.

Further, on the surface of the head substrate 25, as shown in FIG. 8, in general, the head substrate 25 is made to correspond to the nozzle holes 34 formed by etching in the flow path substrate 32.
A metal nozzle plate 39 having an ink ejection hole 38 having an accurate position and diameter formed by precision processing is attached.

Further, the head substrate 25 is provided on the inward flange portion 52 of the stepped opening window 24 of the head frame 22.
Ink through holes 53 corresponding to the six ink supply ports 36 formed in the vibration plate 33 are formed in a penetrating manner.

Inside the head frame 22, the ink supply plates 26 and 27 arranged on the back surface side of the head substrate 25 are respectively arranged in the head frame 22 as shown in FIGS. 3, 4 and 6. The first plate 26 and the second plate 27, which have a planar shape corresponding to the planar shape of the internal space, are stacked, and the first plate 26 has three ink introduction holes 40 in the longitudinal direction.
Are formed in a penetrating manner. The second plate 27 has three ink introduction holes 40 of the first plate 26 on the back surface side.
Ink introduced through the second plate 27
Ink grooves 41 for distributing to two positions in the width direction of the
Are formed, and ink supply holes 42 penetrating to the front surface side are formed at both ends of each ink groove 41. The front surface side opening of the ink supply hole 42 is opened on the bulging portion 55 formed on the front surface side of the second plate 27. The planar position of each ink supply hole 42 is determined by the head substrate 25 described above.
The positions of the ink supply ports 36 formed in the back side vibration plate 33 and the positions of the ink through holes 53 formed in the inward flange portion 52 of the stepped opening window 24 of the head frame 22 are made to correspond. In addition, 3 formed on the first plate 26
The one ink introduction hole 40 corresponds to the three ink supply ports 43 formed in the main frame 21, and Y, M, C formed in the color ink cartridge 23 inserted into the main frame 21. The ink nozzles 44 for the respective colors are communicated with the respective ink introduction holes 40 of the ink supply plate 26 from the ink supply port 43 via the seal bush 45.

Further, between the head substrate 25 and the ink supply plates 26 and 27, a flexible substrate 28 for supplying electric power to each piezoelectric element 37 mounted on the back surface of the head substrate 25 is interposed. Flexible substrate 28
Is a patterned conductor foil formed on the base of a polyimide film and covered with an insulating film while leaving the terminal portion. As shown in detail in FIG. 9, in this embodiment, the flexible substrate 28
Has terminal pads 45 for individual electrodes arranged at one end, and each individual electrode is electrically connected to a comb-teeth-shaped terminal portion 46 corresponding to the arrangement of the piezoelectric elements 37 on the head substrate 25. ing. The ground wiring pattern 47 is routed around the bundle of individual electrode wiring patterns. Further, the second plate 27 is provided on an appropriate portion of the flexible substrate 28.
An opening 56 that fits into the front side bulging portion 55 is formed.

The base end portion of the flexible substrate 28 is also backed up by a reinforcing plate 48 made of glass epoxy or the like in order to mount the drive IC 60 stably and without any inconvenience. Each output pad of the drive IC 60 mounted on the part and the terminal pad 45 for each individual electrode are connected by wire bonding. At the base end of the flexible substrate 28, power is supplied to the driving IC 60.
Wiring patterns 49 for inputting control signals, print data signals, etc. are formed, and each wiring pattern and drive IC
The predetermined pads on 60 are also connected by wire bonding. The drive IC 60 or the bonding wires connecting the wiring patterns and the terminal pads to each other are covered with a protective coat 50 made of epoxy resin or the like.

As described above, the flexible substrate 28 has the piezoelectric element 37 having the comb-teeth-shaped terminal portions 46 forming the individual electrodes attached to the back surface side of the head substrate 25.
And is interposed between the back surface side of the head substrate 25 and the ink supply plates 26 and 27. In order to ensure the contact between the individual electrode 46 and each piezoelectric element 37, a part of the flexible substrate 28 is elastically pressed toward the back surface of the head substrate 25 by the sponge-like elastic member 51. ing. The elastic member 25 also plays a role of surely bringing the ground wiring pattern 47 formed on the flexible substrate 25 into contact with the ground electrode coating (not shown) of the head substrate 25.
In the assembled state, the IC mounting portion of the flexible board 28 is fixed to an appropriate side surface portion of the main frame 21 by, for example, bonding.

The ink jet print head 20 having the above-described structure moves in the scanning direction shown in FIGS. 1 and 5 and prints on the recording paper by the following operation.

According to the print data, the drive IC turns on the corresponding individual electrode 46 to apply a voltage to the piezoelectric element 37 corresponding to the selected nozzle hole 34. The piezoelectric element 37 to which a voltage is applied in this manner causes the diaphragm 33 to bend in a concave manner due to its deformation. Then, the volume of the pressure chamber 29 is forcibly reduced by that amount, and ink droplets of an amount corresponding to the volume reduction are ejected to the outside from the nozzle holes 34 or the ink ejection holes 38 of the nozzle plate. When the piezoelectric element 37 and the vibration plate 33 are restored, the ink supply paths 31 _Y , 31 _M , 3 are generated due to the capillary pressure.
1 _C of ink is replenished to the pressure chamber 29 through the constriction passage 30 to prepare for the next printing operation.

In the ink jet print head 20 having the above structure, the plurality of pressure chambers 29 formed in the head substrate 25 are radially arranged from the nozzle hole forming region like the conventional ink jet print head of this type shown in FIG. Instead of being formed so as to extend in a straight line, it is formed so as to extend outward at a right angle to the nozzle rows on both sides of the linear nozzle row. Therefore, the formation region of the pressure chambers 29 is basically limited to the length range of the row of the nozzle holes 34, and if the length of the pressure chambers 29 is set to an appropriate length, the same number of nozzles and the same arrangement of nozzles as in the conventional case are formed. Even when the head substrate having the holes is formed, the area of the head substrate can be made significantly smaller than that of the conventional head substrate. As a result, since the photosensitive plate glass is subjected to the etching process to form the concave pressure chambers, the ink supply paths, etc., the head substrate, which has a high manufacturing cost, can be manufactured more from a certain material. As a result, the manufacturing cost of the head substrate is reduced.
Further, since the planar shape of the head substrate can be remarkably miniaturized as compared with the conventional one, it becomes possible to effectively avoid the occurrence of defects such as cracks in the vibration plate due to thermal stress. The strength, life and performance of the head substrate, which can be said to be the heart of the product, are stabilized.

Further, the ink jet print of the above-mentioned form
In the head 20, for each color of Y, M and C,
An ink supply path commonly connected to the outer end of the pressure chamber
31 _Y, 31_M, 31_CWill be formed in two places
You. Therefore, the ink supply path is looped around.
Each ink supply path is shorter and narrower than the conventional one.
Will be enough. Therefore, the formation area of the ink supply path
Can also save that much, so the head substrate
The planar shape of can be further miniaturized. And
Since it is possible to narrow the ink supply path,
The thermal stress may cause cracks on the diaphragm.
The condition can also be avoided more effectively
Become.

Actually, when forming a head substrate having the same number of nozzle holes, the nozzle holes 34, the pressure chamber 29 and the ink supply paths 31 _Y , 3 as in the present invention are formed.
When the arrangement of 1 _M and 31 _C is taken, the planar size of the head substrate is about 1/4 or less as compared with the conventional configuration as shown in FIGS.

Of course, the present invention is not limited to the above embodiment. Although the configuration of the color print head is described in the embodiment shown in the drawings, the present invention can be similarly applied to a monochrome print head. In this case, in the case of a color printer, three ink supply paths 31 _Y , 31 _M , and 31 _C are formed on each side of the nozzle row so as to correspond to the three groups. On each side of the direction, ink supply passages that are commonly communicated with all the pressure chambers may be formed. In this case, the ink cartridge 23 is provided with one ink nozzle, and the ink supply plates 26 and 27 are correspondingly provided.
May be configured to be distributed from one ink supply port to the ink supply path of the head substrate.

Even when the same head substrate 25 as that of the embodiment shown in the figure is used, the ink supply plates 26 and 27 are connected from one ink supply port to six ink supply passages of the head substrate. The ink paths may be distributed.

Further, in the embodiment shown in the figure, the nozzle holes provided in the head substrate are arranged in a staggered pattern in two rows, but it is always necessary to arrange them in a staggered pattern. Also,
Even if they are arranged in one row, the pressure chambers are extended to one side in the width direction of the head substrate for the odd-numbered nozzle holes, and the pressure chambers are extended to the other side in the width direction of the head substrate for the even-numbered nozzle holes. By doing so, the same advantages as described above can be enjoyed.

Further, in the embodiment shown in the figure, a color head and a monochrome head are provided side by side on one main frame, but this is not the gist of the present invention, and the color It is, of course, within the scope of the present invention to configure the main frame so that only the head for monochrome or the head for monochrome is mounted.

[Brief description of drawings]

FIG. 1 is an overall external perspective view of an embodiment of an inkjet printhead according to the present invention.

FIG. 2 is an exploded perspective view showing a part of an embodiment of an inkjet print head according to the present invention.

FIG. 3 is a perspective view showing the components mounted on the head frame of the inkjet print head shown in FIGS. 1 and 2 in an exploded manner.

FIG. 4 is an exploded perspective view showing a configuration of an ink supply plate in the parts shown in FIG.

FIG. 5 is an enlarged front view of the head frame.

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5;

FIG. 7 is a partially enlarged plan view of a head substrate.

FIG. 8 is a sectional view taken along the line VIII-VIII in FIG. 7;

FIG. 9 is a plan view of a flexible substrate.

FIG. 10 is a front view of an inkjet print head according to a conventional example.

11 is an enlarged sectional view taken along line XI-XI of FIG.

[Explanation of symbols]

20 inkjet print head 21 main frame 22 head frame 23 ink cartridge 25 head substrate 26 ink supply plate 27 ink supply plate 28 flexible substrate 29 pressure chamber 30 narrow passages 31 _Y , 31 _M , 31 _C ink supply passage 32 flow passage substrate 33 vibration Plate 34 Nozzle hole 37 Piezoelectric element

Claims (5)

[Claims] 1. A plurality of nozzle holes are opened on the front surface side, and a plurality of pressure chambers communicating with the nozzle holes or ink supply paths communicating with the pressure chambers are formed in a concave shape on the back surface side. An ink jet print head comprising a head substrate having a flow channel substrate and a vibration plate attached to the back surface side of the flow channel substrate, wherein the nozzle holes are linearly arranged in one or two rows. The pressure chambers are formed on both sides of the row of nozzle holes so as to extend parallel to each other outward of the head substrate at a constant angle with respect to the row of nozzle holes. The inkjet print head is characterized in that the supply passage is formed so as to be commonly communicated with the outer ends of a plurality of adjacent pressure chambers on each side of the row of nozzle holes. 2. A plurality of nozzle holes are opened on the front surface side, and a plurality of pressure chambers communicating with the respective nozzle holes or ink supply paths communicating with the respective pressure chambers are formed in a concave shape on the rear surface side. An ink jet print head comprising a head substrate having a flow channel substrate and a vibrating plate attached to the back surface side of the flow channel substrate, wherein the nozzle holes are linearly arranged in two rows in a staggered pattern. The pressure chambers corresponding to the respective rows of the nozzle holes are formed so as to extend outwardly at right angles to the rows of the nozzle holes and extend parallel to each other. The pressure chambers are divided into a plurality of groups in the arrangement direction of the nozzle holes, and the ink supply path is commonly connected to the outer ends of the pressure chambers of the same group on each side of the row of nozzle holes. Formed into It is characterized in that is, an ink jet printhead. 3. The plurality of groups are groups corresponding to Y, M, and C, and for each group, two ink supply passages are formed on both sides of the row of the nozzle holes on the head substrate. The inkjet printhead of claim 2. 4. An ink supply plate is arranged on the back surface side of the head substrate, and the ink supply plate is supplied with ink from one ink supply port for each of Y, M, and C on the back surface side. The ink jet print head according to claim 3, wherein the ink is distributed to each of two ink supply paths on the head substrate. 5. The ink jet print head according to claim 4, further comprising a main frame on which an ink cartridge is mounted, and the main frame is also mounted with a head frame that accommodates the flow path plate and the head substrate. .