JP2003063010A - Ink jet printing head and ink jet printer - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent air bubbles from staying in an ink flow path and to suppress crosstalk during ink ejection. SOLUTION: An ink jet nozzle 33 is formed on a nozzle plate 32 on a front surface of a head, a pressure chamber 37 is provided behind the nozzle plate 33, and an ink reservoir 39 communicates with the pressure chamber 73. The ink reservoir 39 has an ink supply path 49.
Is connected. The diameter of the supply path 39 is narrowed down at an outlet 49B connected to the ink reservoir 39, and the diameter at the outlet is smaller than the width and the depth of the ink reservoir 39. The outlet 49B of the ink supply path is connected to the ink reservoir 39 at a location remote from the connection point with the pressure chamber 37 of the ink reservoir 39, except for the connection point with the outlet 49B of the ink supply path. 3
The back surface 9 is covered with a film 43 having flexibility and elasticity, and can absorb the pressure of the ink jet from the pressure chamber 37.

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, and more particularly to improvement of an ink flow path for preventing accumulation of bubbles and crosstalk during ink ejection.

[0002]

2. Description of the Related Art FIG. 1 shows a typical sectional structure of a conventional ink jet print head 1 related to the present invention.

The nozzle plate 2 on the front surface of the head 1 has a large number of ink discharge nozzles 3 arranged in a direction penetrating the paper surface of FIG.
have. Behind this nozzle plate 2, a large number of pressure chambers 5 (arranged in a direction penetrating the plane of the drawing) communicating with each nozzle 3, and a common ink reservoir 7 for supplying ink to these pressure chambers 5 ( Along with the arrangement of the pressure chambers 5) extending in a direction penetrating the plane of the drawing. An ink supply path 9 that carries ink from an ink cartridge (not shown) penetrates the casing 11 of the head 1 and is connected to the ink reservoir 7. Normally, the ink supply passage 9 is connected to the central portion of the ink reservoir 7 which extends long in the direction of penetrating the drawing.

The back surfaces of the pressure chambers 5 and the ink reservoir 7 are covered with a flexible or elastic film 13, and a rigid reinforcing plate 15 such as a stainless steel plate is laminated on the film 13. . 2 is a cross-sectional view of the reinforcing plate 15 taken along the line AA of FIG. 1 (note that the cross section of the head of FIG. 1 is taken along the line BB of FIG. 2). As shown in FIG. 2, the reinforcing plate 15 has a plurality of holes 17, 19,
21 is formed by an etching method and has a rectangular hole 1
7 corresponds to the back surface of the row of pressure chambers 5 and has a circular hole 19 in the center.
Corresponds to the outlet of the ink supply path 9 to the reservoir 7, and the wing-shaped holes 21 on both sides thereof contact the back surface of a portion other than the central portion of the reservoir 7. Further, a large number of strip-shaped island portions 18 existing inside the holes 17 are located on the back surface of each pressure chamber 5.

Referring again to FIG. 1, in the film 13 on the back surface of each pressure chamber 5, the tips of the comb-teeth-shaped portions of the piezoelectric element 23 are separated by the island portions 18 shown in FIG. Are joined together. The piezoelectric element 23 is fixed to the casing 11, and each comb tooth portion of the piezoelectric element 23 is connected to the cable 25.
The film 13 in each pressure chamber 5 reciprocates to generate a pressure in each pressure chamber 5 by the expansion and contraction motion of the nozzles 3 in response to a signal from the nozzles 3 to eject ink. At the same time, a jet of ink also flows from the pressure chamber 5 to the reservoir 7, but the film 13 covering the back surface of the reservoir 7 absorbs the pressure of this jet.

[0006]

The ink flowing from the ink cartridge through the supply passage 9 to the reservoir 7 may contain air bubbles. In the worst case, the bubbles may grow up to the diameter of the supply passage 9, but such large bubbles may be trapped and accumulated near the connection between the supply passage 9 and the reservoir 7. Then, the ink flow becomes poor and the ink cannot be normally ejected from the nozzle.

When ink is ejected, the ink jet from the pressure chamber 5 triggers in the reservoir 7 to oscillate an MC circuit consisting of the compliance C of the film 13 on the back surface of the reservoir and the inertance M of the ink supply path 9. Pressure oscillations may occur. Then, a problem (referred to as crosstalk) such as variation in ink ejection speed or ink ejection from other non-driving nozzles 3 occurs.

Crosstalk is likely to occur when the nozzles near the center of the nozzle row are driven. The reason is as follows. In this case, the ink jet flows from the pressure chamber 5 near the center to the center of the reservoir 7, that is, near the connection with the ink supply path 9. However, in the vicinity of the central portion of the reservoir 7, the rear surface thereof is, as shown in FIG. 2, the peripheral portion 15A of the ink supply passage outlet hole 19 of the reinforcing plate 15 (this is to be joined to the peripheral portion of the outlet of the ink supply passage 9). There is no jet escape because it is covered with (which is a necessary part). Therefore, a high-pressure wave is generated in this central portion and propagates to the periphery, causing problems such as ink ejection from other non-ejection nozzles.

Therefore, an object of the present invention is to prevent the retention of air bubbles in the ink flow path.

Another object of the present invention is to suppress crosstalk during ink ejection.

[0011]

According to a first aspect of the present invention, there is provided an ink jet print head having a plurality of ink ejection nozzles arranged in a row and a plurality of ink ejection nozzles respectively communicating with the nozzles. Of the pressure chambers, an ink reservoir extending along the row of the pressure chambers, which is in common communication with the pressure chambers, and has a predetermined width and depth, and at least part of the outer surface of the ink reservoir is deformable. And a flexible film covered with the ink supply path and an ink supply path communicating with the ink reservoir. The region where the flexible film covers the ink reservoir in a deformable state is continuous in the vicinity of the pressure chambers along the row of pressure chambers and at least in the range from one end to the other end of the pressure chamber row. I'm wandering around.

An ink jet print head according to a second aspect of the present invention includes a plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row which communicate with these nozzles, respectively. An ink reservoir having a predetermined width and a predetermined depth, which extends along the row of pressure chambers and communicates with the pressure chambers in common, and an ink supply path that communicates with the ink reservoirs are provided. The outlet of the ink supply passage is arranged at the center of the ink reservoir and on the side opposite to the pressure chamber side.

An ink jet print head according to a third aspect of the present invention includes a plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row which communicate with the nozzles, respectively. An ink reservoir having a predetermined width and depth, which extends along the row of pressure chambers, and which communicates with the pressure chambers in common, an ink supply passage communicating with the ink reservoir, and at least a part of the outer surface of the ink reservoir. A flexible film which covers the deformable state and thereby acts to absorb the pressure ejected from the pressure chamber to the ink reservoir. The outlet of the ink supply path is located at the central portion of the ink reservoir in the direction along the row of pressure chambers, and is arranged at a position close to the side opposite to the pressure chamber side,
The width of the outlet of the ink supply path is smaller than the width of the ink reservoir. Further, the region of the flexible film that covers the ink reservoir in a deformable state is continuous in the vicinity of the pressure chambers along the row of pressure chambers, at least in the range from one end to the other end of the pressure chamber row. I'm wandering around.

According to this ink jet print head,
With respect to the ink jet from any pressure chamber, the pressure of the jet is effectively absorbed by the flexible film to reduce crosstalk.

The present invention further comprises an ink jet print head having the above-described structure, a carriage mechanism for moving the ink jet print head, a paper feed mechanism for conveying the paper, and a control circuit for driving and controlling these. We also offer inkjet printers.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a sectional structure of an ink jet print head 31 according to an embodiment of the present invention.

The nozzle plate 32 on the front surface of the head 31
Has a large number of ink discharge nozzles 33 arranged in a line in a direction penetrating the plane of the drawing of FIG. This nozzle plate 3
A spacer 35 made of, for example, silicon is bonded to the back surface of the second member 2. In the spacer 35, a number of pressure chambers 37 (arranged in a row penetrating the plane of the drawing) communicating with each nozzle 33 are formed by etching.
A common ink reservoir 39 (which extends in the direction of penetrating the plane of the drawing along the arrangement of the pressure chambers 37) that supplies ink to the pressure chambers 37 is formed. Each pressure chamber 37
Is connected to the reservoir 39 through a very narrow channel 41.

A flexible and elastic film 43 made of resin or metal is attached to the back surface of the spacer 35, and this film 43 is used as the pressure chamber 37 and the reservoir 3.
It covers the back of 9. A rigid reinforcing plate 45 such as a stainless steel plate is laminated on the film 43 from the back surface thereof. The laminated structure of the nozzle plate 32, the spacer 35, the film 43, and the reinforcing plate 45 described above is called a flow path unit 46. The casing 47 of the head 31 is joined to the back surface of the flow path unit 46. Then, the ink supply path 49 that carries the ink from the ink cartridge (not shown) is
Through the ink reservoir 39 in the channel unit 45.
Is connected to the central part of. The ink supply path 49 is tapered from an inlet 49A connected to the ink cartridge to an outlet 49B connected to the ink reservoir 39. Therefore, the cross-sectional area of the ink supply passage 49 is equal to the outlet 49.
It is the smallest at B, which helps prevent bubbles from staying as will be described later, and also contributes to suppressing crosstalk by increasing the compliance of the film 43 on the back surface of the reservoir 39.

On the film 43 on the back surface of each pressure chamber 37,
The tips of each of the piezoelectric elements 50 (extending in the direction of penetrating the paper along the row of the pressure chambers 37) in a comb-like shape are joined via island portions 58 of the reinforcing plate 45, which will be described later. ing. The piezoelectric element 50 is fixed to a heavy holding block 51 made of, for example, stainless steel, and the holding block 51 is fixed to the casing 47 with an adhesive 53 or the like. A signal cable 55 is connected to the piezoelectric element 50. The signal provided from the cable 55 causes each comb-tooth portion of the piezoelectric element 50 to expand and contract, causing the film 43 on the back surface of each pressure chamber 37 to reciprocate to generate pressure in each pressure chamber 37. Ink is ejected from each nozzle 3. At the same time, a jet of ink also flows from the pressure chamber 37 to the reservoir 39. However, as will be described in detail below, the pressure of this jet is changed by the film 43 covering the back surface of the reservoir 39 as shown in FIG. It is absorbed more effectively than the head.

FIG. 4 is a reinforcing plate 4 taken along the line CC of FIG.
5 is a cross-sectional view of the spacer 35 taken along line D-D of FIG. 3 (note that the cross-sectional view of the head taken along line EE of FIGS. 4 and 5 is shown in FIG. 3). Is a cross-sectional view of).

As shown in FIG. 4, a plurality of holes 57, 59 and 61 are formed in the reinforcing plate 45 by an etching method. As can be seen by comparing FIGS. 4 and 5, the rectangular hole 57 of the reinforcing plate 45 is formed in the pressure chamber 37 in the spacer 35.
A large number of strip-shaped island portions 58 located on the back surface of each of the pressure chambers 37 and located inside the rectangular holes 57 are located on the back surfaces of the individual pressure chambers 37. It serves as an intermediary for joining the tips of the comb teeth to the film 43 on the back surface of each pressure chamber 37. Also,
The elliptical or oval hole 59 shown in FIG. 4 corresponds to the supply passage outlet 49B connecting the reservoir 39 and the ink supply passage 49 shown in FIG. 5, and the portion 45A surrounded by the broken line around the elliptical hole 59 is It is a portion for adhering to the peripheral portion of the outlet of the ink supply path 49. Further, the wing-shaped hole 61 shown in FIG. 4 is in contact with the back surface of the reservoir 39 shown in FIG. 5 (excluding the portion of the supply passage outlet 49B).

It should be noted here that, in the reinforcing plate 45, the wing-shaped hole 61 that contacts the back surface of the reservoir 39.
However, it is not interrupted in the central portion like the conventional wing-shaped hole 21 shown in FIG. 2, but is continuous over the entire range from one end of the reservoir 39 to the other end along the row of the pressure chambers 37. This is the point (in the area of this hole 61, the film 4
3 is deformable and absorbs the pressure of the ink jet from the pressure chamber 37, that is, as compliance,
Works). Along with this, the width (diameter in the width W direction) D1 of the supply passage outlet 49B is designed to be smaller than the width W of the reservoir 39, and the supply passage outlet 49B is on the opposite side of the reservoir 39 from the pressure chamber 37. Of the pressure chamber 37 and is separated from the edge on the pressure chamber 37 side. With this configuration,
No matter which pressure chamber 37 ejects ink when ejecting the ink, the film 43 on the back surface of the reservoir 39 can effectively absorb the energy of the ink jet flow, so that crosstalk is reduced.

The operation of this embodiment under the above configuration will be described below.

FIG. 6A shows the flow of bubbles contained in the ink in this embodiment, and FIG. 6B shows that of the conventional head shown in FIG.

In the present embodiment shown in FIG. 6A, the area of the ink supply passage outlet 49B is smaller than the area of the outlet of the ink supply passage 9 of the conventional head shown in FIG. 6B. When the ink flow rates are the same, the flow velocity at the outlet of the ink supply path is semi-proportional to the outlet area, so the flow velocity v1 at the outlet of the ink supply passage of this embodiment is higher than the outlet flow velocity v2 of the conventional head. Further, in this embodiment, the flow velocity in the ink supply passage 49 increases as it approaches the outlet 49B. Therefore, in the present embodiment, the force of pushing bubbles is stronger than that of the conventional head, and the force of pushing bubbles is maximized at the ink supply path outlet 49B, which is the bend angle at which the bubbles are most easily trapped. .

When a bubble grows in the ink supply passage to a size close to the diameter of the supply passage, in the conventional head shown in FIG. 6B, the large bubble 73 hits the wall surface of the reservoir 7 and stays at the outlet of the ink supply passage 9. However, in the present embodiment shown in FIG. 6A, the ink supply path outlet 39B
Since the diameter of the air bubble 71 is small, the bubbles 71 are also small and easily pass through the reservoir 39.

FIG. 7A shows the compliance C of the film 43 on the back surface of the reservoir 39 and the inertance M of the ink supply path 49 in this embodiment.
(B) shows an equivalent circuit of an ink flow path having this compliance C and inertance M (R shows the flow path resistance due to viscosity and the like, and I shows the ink flow rate).

From the pressure chamber 37 to the reservoir 3 when ejecting ink.
The jet of the ink jet to 9 is like the step-like disturbance added to the equivalent circuit of FIG. 7B, which causes the MC circuit to oscillate. As is clear from the circuit theory, the larger C is and the smaller M is, the smaller the pressure amplitude of oscillation is. In the present embodiment, as described with reference to FIGS. 4 and 5, the area where the film 43 acts as the compliance on the back surface of the reservoir 39 is wider than that of the conventional head, and there is no discontinuity at the central portion unlike the conventional head. , C is larger than that of the conventional head. Further, the ink supply passage 49 is thin at the outlet, but becomes thicker toward the inlet, so that the M of the entire ink supply passage 49 is small. Therefore, the pressure amplitude in the reservoir 39 is small and the crosstalk is small.

FIG. 8 shows a preferable dimensional relationship for making the effects of the bubble retention prevention and the crosstalk reduction described above effective.

That is, the outlet 49B of the ink supply path 49
It is desirable that the width (diameter) D1 of the reservoir is smaller than the depth D2 of the reservoir 39. As a result, bubbles that have entered the reservoir 39 from the ink supply path 49 can easily pass through the reservoir 39. However, it is not always necessary that D1 <D2, and even if D1> D2, the bubbles do not stay if the ink flow velocity is appropriately high. The width W of the reservoir 39 is preferably larger than the outlet width D1 of the ink supply passage 49, and more preferably larger than the depth D2 of the reservoir 39. This allows the film 4 on the back of the reservoir to
3 becomes large, and the crosstalk reducing effect becomes large.

FIG. 9 shows some variations on the shape or structure of the ink supply channel 49 in which the principles of the present invention can be utilized.

In the example of FIG. 9A, the ink supply path 49
Are tapered near the inlet 49A and near the outlet 49B so that the inlet 49A and the outlet 49B are thin and the other portions are thick and have the same diameter. Two members 81 having holes of such a shape, It is made by joining 83. In the ink supply path 49 of FIG. 9B, only the outlet 49B is tapered so that the outlet 49B is the thinnest and the other portions are thick and have the same diameter. Two holes having such a shape are formed. Member 85,
It is made by joining 87. The ink supply path 49 in FIG. 9C is tapered slightly upstream of the outlet 49B, the outlet 49B has the smallest diameter and the same diameter, and the upstream side from the tapered portion has the same diameter that is thick. , Is formed by joining three members 89, 91, 93 having holes of such a shape.

FIG. 10 shows another modification of the ink supply passage 49.

FIGS. 10B and 10C are respectively shown in FIG.
FIG. 6A is a cross-sectional view of the ink supply path 49 taken along line FF and line GG in FIG. The cross section of the ink supply path 49 has an outlet 4
9B has an elliptical shape, which contributes to increase the compliance C of the film on the back surface of the reservoir 39, and has a circular shape in the other thick portion, which minimizes the inner stance M of the ink supply path 49. Contribute.

FIG. 11 shows still another modification of the ink supply passage 49.

The ink supply path 49 obliquely penetrates through the casing 47 of the head, and a taper is provided near the outlet so that the outlet 49B is the thinnest.
The number 101 indicates a needle inserted into an ink cartridge (not shown), and the number 103 indicates a filter for removing dust of ink. Since the ink cartridge is usually much larger than the reservoir 39, an ink supply path 49 is obliquely arranged to guide the ink from a predetermined position of the ink cartridge to the reservoir 39.

FIG. 12 is a cross-sectional view of a modified example of the reinforcing plate 45 for explaining another arrangement example of the ink supply path.

In the reinforcing plate 45, the ink reservoir 39
One end of the hole 113 corresponding to the back surface of the ink chamber extends outward from the hole 57 corresponding to the rear surface of the row of pressure chambers, and a hole 111 corresponding to the outlet of the ink supply path is formed beside the extending end portion of the hole 1143. Has been done. This means that the ink reservoir extends to a position out of the row of pressure chambers, and the outlet of the ink supply path is connected to this extended portion. According to this structure, the ink jet from the pressure chamber can be absorbed in the entire region of the reservoir in front of the pressure chamber, so that the crosstalk reducing effect is further improved. But,
The size of the head increases as the ink supply path is arranged outside the row of pressure chambers.

FIG. 13 shows the overall construction of an ink jet printer using the ink jet print head 31 according to the above embodiment.

The printer 120 has the above-described inkjet print head 31, a carriage mechanism 123 that moves the inkjet print head, a paper feed mechanism 125 that conveys paper, the inkjet print head 121, and the carriage mechanism 123. And a control circuit 121 for driving and controlling the paper feeding mechanism 125.
Such a printer can be used for various printing applications such as an output device of a computer system, a facsimile terminal device, a word processor printer, and an ATM printer.

The embodiment of the present invention has been described above.
The above embodiment is merely an example for explaining the present invention, and the present invention is not limited to the above embodiment. Therefore, the present invention can be implemented in various forms other than the above embodiment.

[Brief description of drawings]

FIG. 1B of FIG. 2 of a conventional inkjet printhead.
-A sectional view taken along line B.

FIG. 2 is a cross-sectional view of the reinforcing plate 15 taken along the line AA of FIG.

FIG. 3 is a cross-sectional view of the inkjet print head according to the embodiment of the present invention taken along line EE of FIGS.

4 is a cross-sectional view of the reinforcing plate 45 taken along the line CC of FIG.

5 is a cross-sectional view of the spacer 35 taken along the line DD of FIG.

FIG. 6 is a view showing the flow of bubbles contained in ink in the present embodiment (A) in comparison with the conventional head (B).

FIG. 7 shows the compliance C of the film 43 on the back surface of the reservoir 39 and the inertance M of the ink supply path 49, and the compliance C and the inertance M in the present embodiment.
FIG. 6 is a diagram showing an equivalent circuit of an ink flow path having a line.

FIG. 8 is a view showing a preferable dimensional relationship in the present embodiment.

FIG. 9 is a diagram showing some modifications of the shape or structure of the ink supply path 49 in which the principle of the present invention can be used.

FIG. 10 is a view showing still another modified example of the ink supply passage 49.

FIG. 11 is a view showing still another modified example of the ink supply passage 49.

FIG. 12 is a cross-sectional view of a modified example of the reinforcing plate 45 for explaining another arrangement example of the ink supply paths.

FIG. 13 is an overall configuration diagram of an inkjet printer using the inkjet print head of the present invention.

[Explanation of symbols]

31 inkjet print head 33 nozzles 35 Spacer 37 Pressure chamber 39 ink reservoir 43 films 45 Reinforcement plate 46 flow path unit 47 casing 49 ink supply path 49A Ink supply inlet 49B Ink supply outlet 50 Piezoelectric element 57, 59, 61, 111, 113 Holes in the reinforcing plate

Claims (6)

[Claims] 1. A plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, each of which communicates with the nozzle, and a plurality of pressure chambers extending along the row of the pressure chambers. An ink reservoir having a predetermined width and depth, which communicates in common with each other, a flexible film which covers at least a part of an outer surface of the ink reservoir in a deformable state, and an ink supply which communicates with the ink reservoir A region, the region covering the ink reservoir in a deformable state of the film, in the vicinity of the pressure chamber, along the row of pressure chambers, from at least one end of the row of pressure chambers. Inkjet print head that extends continuously up to the other end. 2. A plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, each of which communicates with the nozzle, and a plurality of pressure chambers extending along the row of the pressure chambers. An ink reservoir having a predetermined width and depth, which communicates with each other in common, and an ink supply path communicating with the ink reservoir, and an outlet of the ink supply path is a central portion of the ink reservoir, An ink jet print head disposed at a position near the side opposite to the pressure chamber side. 3. A plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, which communicate with the nozzles, respectively, and a plurality of the pressure chambers extending along the row of the pressure chambers. An ink reservoir having a predetermined width and depth, which communicates in common with the ink reservoir, an ink supply passage which communicates with the ink reservoir, and at least a part of an outer surface of the ink reservoir which is deformably covered. A flexible film that acts to absorb the pressure ejected from the pressure chambers into the ink reservoirs, the outlet of the ink supply passages of the ink reservoirs in a direction along a row of the pressure chambers. The film is arranged in a central portion and at a position closer to the side opposite to the pressure chamber side, the width of the outlet of the ink supply passage is smaller than the width of the ink reservoir, and the film is deformable. The region covering the ink reservoir extends continuously in the vicinity of the pressure chambers along the row of the pressure chambers, at least in the range from one end to the other end of the pressure chambers. Inkjet print head. 4. An inkjet print head, a carriage mechanism for moving the inkjet print head, a paper feed mechanism for carrying a paper, and a control circuit for driving and controlling the inkjet print head, the carriage mechanism and the paper feed mechanism. And a plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, respectively communicating with the nozzles, extending along the row of the pressure chambers, An ink reservoir having a predetermined width and depth that communicates with the plurality of pressure chambers in common, a flexible film that covers at least a portion of the outer surface of the ink reservoir in a deformable state, and the ink reservoir An ink supply path communicating with the ink reservoir, the film covering the ink reservoir in a deformable state. Range is in the vicinity of the pressure chamber, along the columns of the pressure chambers, ink jet printers over continuously in a range from one end of the column of at least the pressure chamber to the other. 5. An inkjet print head, a carriage mechanism for moving the inkjet print head, a paper feed mechanism for carrying a paper, and a control circuit for driving and controlling the inkjet print head, the carriage mechanism and the paper feed mechanism. And a plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, respectively communicating with the nozzles, extending along the row of the pressure chambers, An ink reservoir having a predetermined width and depth, which communicates with the plurality of pressure chambers in common, and an ink supply path which communicates with the ink reservoir are provided, and an outlet of the ink supply path has a center of the ink reservoir. An ink jet printer which is disposed at a portion closer to the side opposite to the pressure chamber side. 6. An inkjet print head, a carriage mechanism for moving the inkjet print head, a paper feed mechanism for carrying paper, and a control circuit for driving and controlling the inkjet print head, the carriage mechanism and the front paper feed mechanism. And a plurality of ink ejection nozzles arranged in a row, a plurality of pressure chambers arranged in a row, respectively communicating with the nozzles, extending along the row of the pressure chambers, An ink reservoir having a predetermined width and depth that communicates with the plurality of pressure chambers in common, an ink supply path that communicates with the ink reservoir, and at least a part of an outer surface of the ink reservoir in a deformable state. A flexible film that covers and thereby acts to absorb the pressure ejected from the pressure chamber into the ink reservoir. Where the outlet of the ink supply passage is the central portion of the ink reservoir in the direction along the row of the pressure chambers and is close to the side opposite to the pressure chambers side. The width of the outlet of the ink supply path is smaller than the width of the ink reservoir, and the region that covers the ink reservoir in a deformable state of the film is near the pressure chamber, An ink jet printer that continuously extends along at least one row of the pressure chambers from one end to the other end.