CN110843342A

CN110843342A - Liquid ejection substrate, liquid ejection head, and liquid ejection apparatus

Info

Publication number: CN110843342A
Application number: CN201911161947.XA
Authority: CN
Inventors: 奧岛真吾; 刈田诚一郎; 青木孝纲; 永井议靖; 驹宫友美
Original assignee: Canon Inc
Current assignee: Canon Inc
Priority date: 2016-01-08
Filing date: 2017-01-06
Publication date: 2020-02-28
Also published as: JP2017124617A; RU2016151773A; RU2016151773A3; CN106956509A; JP2023126669A; JP6987498B2; JP2022016691A; JP7401508B2; AU2016277743A1; CN106956509B; KR102179743B1; RU2664201C2; KR20200096191A; MY193592A; BR102017000247A2; KR20170083498A

Abstract

The invention relates to a liquid ejection substrate, a liquid ejection head, and a liquid ejection apparatus. The liquid ejection substrate includes: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, wherein the liquid ejection substrate includes a first portion and a second portion that are offset from each other in a thickness direction of the liquid ejection substrate, wherein the first portion is provided with: a supply channel arranged at one side of the pressure chamber to supply liquid to the pressure chamber; and a recovery channel disposed at the other side of the pressure chamber to recover the liquid from the pressure chamber, and wherein the second portion is provided with: a common supply passage communicating with a plurality of the supply passages; and a common recovery passage communicating with a plurality of the recovery passages.

Description

Liquid ejection substrate, liquid ejection head, and liquid ejection apparatus

The present application is a divisional application of invention patent application No.201710008650.4 entitled "liquid ejection substrate, liquid ejection head, and liquid ejection apparatus" filed on 6/1/2017.

Technical Field

The present invention relates to a liquid ejection substrate, a liquid ejection head, and a liquid ejection apparatus for ejecting various liquids including ink.

Background

For example, in an inkjet print head capable of selectively ejecting ink from a plurality of ejection openings, it is necessary to intensively arrange the ejection openings so as to print a high-quality image with high accuracy. Further, since the ink is thickened due to evaporation of moisture in the ink from the ejection openings, it is necessary to provide a countermeasure that affects a high-quality printing operation.

To cope with such a demand, japanese patent No.4722826 discloses a method of circulating ink through a pressure chamber so that thickened ink inside the pressure chamber communicating with an ejection port does not stagnate therein. Japanese patent No.4722826 discloses a configuration in which a member having a curved ink passage is formed by extruding aluminum, and ink is forced to flow into a pressure chamber corresponding to each of a plurality of ejection ports through the ink passage formed inside the member. Japanese patent No.5264000 discloses a configuration in which a member having a three-dimensionally curved ink passage is formed, and ink is forcibly flowed into a pressure chamber corresponding to each of a plurality of ejection ports through the ink passage formed inside the member.

However, in japanese patent No.4722826 and japanese patent No.5264000, the ink channels have a complex shape, and therefore it is not easy to densely arrange a plurality of ink channels such that ink circulates through a pressure chamber corresponding to each of a plurality of ejection ports that are densely arranged.

Disclosure of Invention

The present invention provides a liquid ejection substrate, a liquid ejection head, and a liquid ejection apparatus capable of circulating liquid through pressure chambers respectively corresponding to a plurality of ejection openings even in the case where the ejection openings are densely arranged.

In a first aspect of the present invention, there is provided a liquid ejection substrate comprising: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, wherein the liquid ejection substrate includes a first portion and a second portion that are offset from each other in a thickness direction of the liquid ejection substrate, wherein the first portion is provided with: a supply channel arranged at one side of the pressure chamber to supply liquid to the pressure chamber; and a recovery channel disposed at the other side of the pressure chamber to recover the liquid from the pressure chamber, and wherein the second portion is provided with: a common supply passage communicating with a plurality of the supply passages; and a common recovery passage communicating with a plurality of the recovery passages.

In a second aspect of the present invention, there is provided a liquid ejection substrate comprising: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, the liquid ejection substrate including: a supply channel that is arranged on one side of the pressure chamber and extends in a direction intersecting a face on which the ejection energy generating element is provided; a recovery channel that is arranged on the other side of the pressure chamber and extends in a direction intersecting a face on which the ejection energy generating elements are provided; a common supply passage communicating with the plurality of supply passages; and a common recovery passage communicating with the plurality of recovery passages, wherein a gap W between the downstream end of the common supply passage and the upstream end of the common recovery passage satisfies a relationship of W < (2 × P)/(Q1 × R) in a case where a passage resistance per unit length from the downstream end of the supply passage to the upstream end of the recovery passage through the pressure chamber is denoted by R, a liquid flow rate flowing through the pressure chamber without ejecting the liquid from the ejection port is denoted by Q1, and a maximum negative pressure capable of ejecting the liquid from the ejection port is denoted by P.

In a third aspect of the present invention, there is provided a liquid ejection substrate comprising: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, the liquid ejection substrate including: a supply channel that is arranged on one side of the pressure chamber and extends in a direction intersecting a face on which the ejection energy generating element is provided; a recovery channel that is arranged on the other side of the pressure chamber and extends in a direction intersecting a face on which the ejection energy generating elements are provided; a common supply passage communicating with the plurality of supply passages; and a common recovery passage communicating with the plurality of recovery passages, wherein in a case where a passage resistance per unit length from the downstream end portion of the supply passage through the pressure chamber to the upstream end portion of the recovery passage is denoted by R, a maximum ejection amount of the liquid ejected from the ejection port is denoted by Q2, and a maximum negative pressure capable of ejecting the liquid from the ejection port is denoted by P, a gap W between the downstream end portion of the common supply passage and the upstream end portion of the common recovery passage satisfies a relationship of W < (2 × P)/(Q2 × R).

In a fourth aspect of the present invention, there is provided a liquid ejection head having a liquid ejection substrate including: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, wherein the liquid ejection substrate includes a first portion and a second portion that are offset from each other in a thickness direction of the liquid ejection substrate, wherein the first portion is provided with: a supply channel arranged at one side of the pressure chamber to supply liquid to the pressure chamber; and a recovery channel disposed at the other side of the pressure chamber to recover the liquid from the pressure chamber, and wherein the second portion is provided with: a common supply passage communicating with a plurality of the supply passages; and a common recovery passage communicating with a plurality of the recovery passages.

In a fifth aspect of the present invention, there is provided a liquid ejection apparatus comprising:

a liquid ejection head comprising: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, the liquid ejection head including: an ejection port array in which a plurality of liquid ejection ports are arranged; a first passage communicating with one side of the pressure chamber; a second passage communicating with the other side of the pressure chamber; a supply channel array in which a plurality of supply channels that supply liquid to the first channels are arranged along an arrangement direction of the plurality of ejection ports, the plurality of supply channels extending in a direction intersecting a face where the ejection energy generating elements are provided; a recovery passage array in which a plurality of recovery passages that recover liquid inside the second passages are arranged along the arrangement direction of the plurality of ejection ports, the plurality of recovery passages extending along the intersecting direction; a common supply passage extending in an arrangement direction of the plurality of ejection ports and communicating with the plurality of supply passages; and a common recovery passage extending in an arrangement direction of the plurality of ejection ports and communicating with the plurality of recovery passages,

a controller configured to control the plurality of ejection energy generating elements; and

a differential pressure generator configured to generate a differential pressure between the common supply passage and the common recovery passage such that the liquid flows through the common supply passage, the pressure chamber, the recovery passage, and the common recovery passage.

In a sixth aspect of the present invention, there is provided a liquid ejection head comprising: an ejection port that ejects liquid; an ejection energy generating element that generates energy for ejecting liquid; and a pressure chamber in which an ejection energy generating element is provided, the liquid ejection head including: an ejection port array in which a plurality of liquid ejection ports are arranged; a first passage communicating with one side of the pressure chamber; a second passage communicating with the other side of the pressure chamber; a supply channel array in which a plurality of supply channels that supply liquid to the first channels are arranged along an arrangement direction of the plurality of ejection ports, the plurality of supply channels extending in a direction intersecting a face where the ejection energy generating elements are provided; a recovery passage array in which a plurality of recovery passages that recover liquid inside the second passages are arranged along the arrangement direction of the plurality of ejection ports, the plurality of recovery passages extending along the intersecting direction; a common supply passage extending in an arrangement direction of the plurality of ejection ports and communicating with the plurality of supply passages; and a common recovery passage extending in an arrangement direction of the plurality of injection ports and communicating with the plurality of recovery passages.

Further features of the invention will be apparent from the following description of exemplary embodiments (with reference to the attached drawings).

Drawings

Fig. 1 is an exploded perspective view showing a liquid ejection substrate of a first embodiment of the present invention;

fig. 2 is an exploded top view showing the liquid ejection substrate of fig. 1;

fig. 3 is a plan view showing a main portion of the liquid ejection substrate of fig. 1;

FIG. 4 is a cross-sectional view taken along line IV-IV of FIG. 3;

fig. 5 is a sectional perspective view showing a main part of the liquid ejection substrate of fig. 1;

fig. 6A is a longitudinal sectional view showing a main part of the liquid ejection substrate of fig. 1;

fig. 6B is a side view showing a main portion of the liquid ejection substrate of fig. 1;

fig. 7 is an explanatory view showing a main part of the liquid ejection substrate of fig. 1;

fig. 8A and 8B are explanatory diagrams respectively showing ink menisci in ejection ports;

fig. 8C is an explanatory diagram showing the relationship between the ejection port aperture and the allowable pressure limit;

fig. 9 is an explanatory diagram showing a positional relationship between the first common supply path and the first common recovery path;

FIG. 10 is a flowchart showing a liquid ejection head manufacturing step;

fig. 11 is an exploded perspective view showing a liquid ejection substrate according to a second embodiment of the present invention;

fig. 12 is an exploded top view showing the liquid ejection substrate of fig. 11;

fig. 13 is an exploded perspective view showing a liquid ejection substrate according to a third embodiment of the present invention;

fig. 14 is an exploded top view showing the liquid ejection substrate of fig. 13;

fig. 15 is an exploded perspective view showing a liquid ejection substrate according to a fourth embodiment of the present invention;

fig. 16 is an exploded top view showing the liquid ejection substrate of fig. 15;

fig. 17A is a plan view showing a main portion of the liquid ejection substrate of fig. 15;

fig. 17B is an explanatory diagram showing an end portion of the ejection array of fig. 17A;

fig. 18A is an explanatory diagram showing the shapes of the first common supply passage and the first common recovery passage;

fig. 18B is an explanatory view showing end portions of the first common supply passage and the first common recovery passage of fig. 18A;

fig. 19 is an exploded perspective view of a liquid ejection substrate according to a fifth embodiment of the present invention;

fig. 20 is an exploded top view showing the liquid ejection substrate of fig. 19;

fig. 21 is an exploded perspective view showing a liquid ejection substrate according to a sixth embodiment of the present invention;

fig. 22 is an exploded top view showing the liquid ejection substrate of fig. 21;

fig. 23 is an explanatory diagram showing an arrangement relationship between a first ink channel and a second ink channel;

fig. 24A, 24B, 24C, 24D, and 24E are perspective views each showing a configuration example having a different liquid ejection head to which the liquid ejection substrate of the present invention is applied;

fig. 25A and 25B are schematic perspective views each showing a configuration example having a different ink jet printing apparatus to which the liquid ejection head of the present invention is applied;

fig. 25C is an explanatory diagram showing an ink supply system for a printhead;

fig. 26 is an explanatory diagram showing a printing apparatus according to a first application example of the present invention;

fig. 27 is an explanatory diagram showing a first circulation pattern among circulation paths applicable to the printing apparatus of fig. 26;

fig. 28 is an explanatory diagram showing a second circulation pattern among the circulation paths applicable to the printing apparatus of fig. 26;

fig. 29 is an explanatory diagram showing the ink circulation amounts in the first circulation pattern and the second circulation pattern;

fig. 30A and 30B are perspective views respectively showing the liquid ejection head of fig. 26;

fig. 31 is an exploded perspective view showing a liquid ejection head;

fig. 32 is a schematic view showing the front and back surfaces of first, second, and third channel members in the liquid ejection head;

fig. 33 is an enlarged perspective view showing a channel formed by joining the first, second and third channel members;

FIG. 34 is a cross-sectional view taken along line XXXIV-XXXIV of FIG. 33;

FIGS. 35A and 35B are perspective views respectively showing a spray module;

fig. 36A, 36B, and 36C are explanatory views each showing a printing element board;

FIG. 37 is a cross-sectional perspective view showing a print element plate taken along line XXXVII-XXXVII of FIG. 36A;

FIG. 38 is an enlarged top view of adjacent portions of two print element plates;

fig. 39A and 39B are perspective views each showing a liquid ejection head according to a second application example of the present invention;

fig. 40 is an exploded perspective view showing the liquid ejection head;

FIG. 41 is an explanatory view showing a passage member constituting a liquid ejection head;

fig. 42 is a perspective view showing a liquid connecting relationship between a printing element plate and a passage member in the liquid ejection head;

FIG. 43 is a cross-sectional view taken along line XXXXII-XXXXXII of FIG. 42;

fig. 44A and 44B are perspective views showing an ejection module of the liquid ejection head;

fig. 45A and 45B are explanatory views showing a printing element board;

fig. 45C is an explanatory view showing the cover plate;

fig. 46 is a diagram showing a second example of a printing apparatus to which the present invention is applicable;

FIG. 47 is an explanatory view showing a printing apparatus of the present invention;

fig. 48 is an explanatory diagram showing a third circulation pattern of the ink circulation path;

fig. 49A and 49B are explanatory views showing the liquid ejection head of the present invention;

FIG. 50 is an exploded perspective view showing the liquid ejection head of the present invention;

FIG. 51 is a schematic explanatory view showing a passage member of the invention;

fig. 52 is an explanatory diagram showing a printing apparatus according to a third application example of the present invention;

FIG. 53 is an explanatory view showing a fourth circulation pattern of an ink circulation path

Fig. 54A and 54B are explanatory views each showing a liquid ejection head according to a third application example of the present invention;

fig. 55A, 55B, and 55C are explanatory views each showing a liquid ejection head according to a third application example of the present invention.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The liquid ejection substrate, the liquid ejection head, and the liquid ejection apparatus of the following embodiments are application examples of an ink ejection substrate (substrate for an ink jet print head) that ejects ink as liquid, an ink jet print head, and an ink jet printing apparatus.

Further, the liquid ejection head and the liquid ejection apparatus of the present invention can be applied to a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printing section, and an industrial printing apparatus combined with various processing devices. For example, liquid ejection heads and liquid ejection devices can be used to manufacture biochips or print electronic circuits. Further, since the embodiments described below are detailed examples of the present invention, various technical limitations can be made. However, the embodiments of the present invention are not limited to the embodiments described in the specification or other detailed methods, but can be modified within the scope of the spirit of the present invention.

(first embodiment)

Fig. 1 to 10 are explanatory views showing a liquid ejection unit 300 according to a first embodiment of the present invention. Here, the liquid ejection unit 300 constitutes an inkjet print head, which is mounted on an inkjet printing apparatus as will be described later.

As shown in fig. 1 and 2, the liquid ejection unit 300 of this embodiment has a six-layered channel structure including an orifice plate 21, a first channel layer 22, a second channel layer 23, a third channel layer 24, a fourth channel layer 25, a fifth channel layer 26, and a sixth channel layer 27. The first channel layer 22 is provided with ejection energy generating elements 12, and the ejection energy generating elements 12 generate ejection energy for ejecting ink as liquid, so the ink inside the pressure chambers 13 can be ejected from the ejection ports 11 of the orifice plate 21 by means of the ejection energy. When the ink inside the pressure chamber 13 is in a stationary state, the pressure inside the pressure chamber 13 is maintained at a negative pressure, in which a meniscus of the ink is formed at the ejection port 11. When a pressure change is generated inside the pressure chamber 13, the ink ejection speed or the ink ejection amount (volume) changes, thus affecting the ink ejection characteristics. In particular, when the pressure inside the pressure chamber 13 becomes lower than a predetermined pressure, ink is not easily ejected.

As the ejection energy generation element 12, an electrothermal conversion element (heater) or a piezoelectric element may be used. In the case of using a heater, the ink inside the pressure chamber 13 becomes bubbles due to heat, and can be ejected from the ejection port 11 by using foaming energy.

As shown in fig. 3, a plurality of ejection openings 11 are densely arranged to form an ejection opening array 16. In this example, four ejection port arrays 16 are formed. As shown in fig. 4, the first common supply channel 17 of the second channel layer 23 communicates with one side (the left side in fig. 4) of each pressure chamber 13 through the single supply channel 14 and the channel 10 corresponding to each pressure chamber 13. Similarly, the first common recovery channel 18 of the second channel layer 23 communicates with the other side (the right side in fig. 4) of each pressure chamber 13 through the single recovery channel 15 and the channel 10 from the pressure chamber 13. The plurality of supply passages 14 and the plurality of recovery passages 15 extend in the thickness direction of the first passage layer 22 and are arranged along the extending direction (first direction) of the ejection port array 16 so as to form a supply passage array and a recovery passage array. The thickness direction of the first channel layer 22 corresponds to a direction intersecting (orthogonal in this example) the liquid ejection substrate face on which the ejection energy generating elements 12 are arranged. The first common supply channel 17 communicates with a first supply port 30 formed in the third channel layer 24, and receives ink supplied from the first supply port 30. Similarly, the first common recovery channel 18 communicates with a first recovery port 31 formed in the third channel layer 24. The plurality of first supply ports 30 are arranged along the extending direction (first direction) of the ejection port array 16 so as to form a first supply port array. Similarly, a plurality of first recovery ports 31 are arranged along the extending direction of the ejection port array 16 so as to form a first recovery port array. In the third channel layer 24, four first supply port arrays and four first recovery port arrays are alternately arranged in parallel. The fourth channel layer 25 is provided with a second common supply channel 32 and a second common recovery channel 33, while the fifth channel layer 26 is provided with a second supply port 34 and a second recovery port 35. The sixth channel layer 27 is provided with a third common supply channel 36 and a third common recovery channel 37.

The first common recovery channel 17 has a configuration in which one side (the side facing the first channel layer 22) in the thickness direction of the second channel layer 23 communicates with the plurality of supply channels 14, and the other side (the side facing the third channel layer 24) communicates with the plurality of first supply ports 30. Similarly, the first common recovery channel 18 has a configuration in which one side in the thickness direction of the second channel layer 23 communicates with the plurality of recovery channels 15 and the other side communicates with the plurality of first recovery ports 31. The second common supply channel 32 has a configuration in which one side in the thickness direction of the fourth channel layer 25 communicates with the plurality of first supply ports 30, and the other side communicates with the plurality of second supply ports 34. Similarly, the second common recovery channel 33 has a configuration in which one side in the thickness direction of the fourth channel layer 25 communicates with the first recovery port 31 and the other side communicates with the second recovery port 35. Further, the third common supply passage 36 communicates with the plurality of second supply ports 34, and the third common recovery passage 37 communicates with the plurality of second recovery ports 35.

The arrangement density of the plurality of second supply ports 34 and the arrangement density of the plurality of second recovery ports 35 are lower than the arrangement density of the plurality of first supply ports 30 and the arrangement density of the plurality of first recovery ports 31. Further, the arrangement density of the plurality of first supply ports 30 and the arrangement density of the plurality of first recovery ports 31 are lower than the arrangement density of the plurality of supply passages 14 and the arrangement density of the plurality of recovery passages 15. The first common supply passage 17 and the first common recovery passage 18 are formed in parallel in the first direction. The second common supply passage 32 and the second common recovery passage 33 are formed in parallel in the second direction. The third common supply passage 36 and the third common recovery passage 37 are formed in parallel in the first direction.

In this way, the liquid ejection unit 300 of this example is formed by laminating a plurality of channel members. The channel formation density in these channel layers increases in the order of the sixth channel layer 27, the fifth channel layer 26, the fourth channel layer 25, the third channel layer 24, the second channel layer 23, and the first channel layer 22. Therefore, the liquid ejection unit 300 can have a configuration in which the plurality of ejection port arrays 16 are densely arranged while suppressing an increase in the size of each element plate and the passage member.

In this embodiment, the first channel layer 22 and the second channel layer 23 are formed in the liquid ejection substrate 100. In the present invention, the configurations of the third channel layer 24 to the sixth channel layer 27 are not particularly limited. Specifically, first and second configuration examples are exemplified below. In the first configuration example, the third channel layer 24 is formed in the cover plate (cover member) 20 or 2020 of the following embodiment of fig. 36C or 45C, and a part of the fourth channel layer 25 is formed in the support member 400 of the following embodiment of fig. 24A to 24E. Another portion of the fourth channel layer 25 is formed in the

first channel member

500 or 50 of the following embodiment of fig. 24A to 24E or 31, and portions of the fifth channel layer 26 and the sixth channel layer 27 are formed in the

second channel member

600 or 60 of the following embodiment of fig. 24A to 24E or 31. Another portion of the sixth channel layer 27 is formed in a third channel member 370 of the embodiment of fig. 31 described below. On the other hand, in the second configuration example, the third channel layer 24 is formed in the

cover plate

20 or 2020, and a part of the fourth channel layer 25 is formed in the support member 400. Another portion of the fourth channel layer 25 and the fifth channel layer 26 is formed in the

first channel member

500 or 50, and the sixth channel layer 27 is formed in the

second channel member

600 or 60. Further, the second common supply passage 32, the second common recovery passage 33, the second supply port 34, and the second recovery port 35 are not limited to the configuration of this example.

Ink supplied from the outside is introduced from the third common supply channel 36 communicating with the ink flow inlet to the pressure chamber 13, sequentially through the second supply port 34, the second common supply channel 32, the first supply port 30, the first common supply channel 17, and the supply channel 14. The ink inside the pressure chamber 13 flows to the outside from the recovery port communicating with the third common recovery passage 37, sequentially passing through the recovery passage 15, the first common recovery passage 18, the first recovery port 31, the second common recovery passage 33, the second recovery port 35, and the third common recovery passage 37. Since the ink circulates in this manner, the thick ink that tends to stagnate inside the pressure chamber 13 can flow to the outside. Therefore, it is possible to suppress the color density variation of the ink and suppress the decrease in the ejection speed of the ink ejected from the ejection openings 11. Hereinafter, such forced flow of ink will be referred to as "ink circulation flow".

In this example, as shown in fig. 3, 4, and 5, the supply passage 14 and the recovery passage 15 are arranged to face each other with the ejection port 11 therebetween. Because the supply channel 14 and the recovery channel 15 face each other in this way, an extremely efficient ink circulation flow is generated inside the pressure chamber 13 and the ejection port 11. Therefore, a decrease in the ink ejection speed and a change in the color density of the ink can be extremely effectively suppressed. Further, the supply passage 14 and the recovery passage 15 are respectively formed at a plurality of positions in a first direction corresponding to the extending direction of the ejection port array 16 so as to correspond to each pressure chamber 13. Since the supply channels 14 and the recovery channels 15 are formed at a plurality of positions, respectively, in this way, the electric wires for driving the ejection energy generating elements 12 can be arranged between the adjacent supply channels 14 and between the adjacent recovery channels 15. Therefore, it is not necessary to arrange the electric wires extending in the first direction between the supply passage 14 and the ejection port 11 and between the recovery passage 15 and the ejection port 11. Therefore, the size of the portion between the supply passage 14 and the injection port 11 and the size of the portion between the recovery passage 15 and the injection port 11 can be further reduced. The number relationship between the supply passage 14 and the ejection port 11 may be one-to-one, one-to-two, or one-to-five, and the number of the pressure chambers 13 communicating with the supply passage 14 is not limited to one of the present embodiments.

In this example, since the ink circulation flow is generated inside the pressure chamber 13 and the ejection port 11, the passage is formed in the following manner.

As shown in fig. 2, the first common supply passage 17 extends in the first direction to communicate with the plurality of supply passages 14 and communicate with the pressure chamber 13 through each of the supply passages 14. Similarly, the first common recovery passage 18 extends in the first direction to communicate with the plurality of recovery passages 15 and communicate with the pressure chamber 13 through each recovery passage 15.

In this way, the first channel layer 22 and the second channel layer 23 are provided with a series of ink channels including the supply channel 14, the recovery channel 15, the first common supply channel 17, and the first common recovery channel 18 and corresponding to the ejection port array 16. By such an ink passage, the ink circulation flow can be generated inside the pressure chambers 13 of the liquid ejection substrate 100 and the ejection ports 11 of the orifice plate 21.

Further, as shown in fig. 6A, the side walls constituting the supply passage 14, the recovery passage 15, the first common supply passage 17, and the first common recovery passage 18 are substantially orthogonal to the front and back surfaces (upper and lower surfaces in the drawing) of the first passage layer 22. Here, the substantially orthogonal state includes the inclination of the taper formed when the first channel layer 22 and the second channel layer 23 are processed. The supply channel 14, the recovery channel 15, the first common supply channel 17 and the first common recovery channel 18 may be formed by, for example, dry etching. Further, the channels may be formed by laser machining or a combination of dry etching and laser machining. The depth directions (vertical directions in fig. 6A) of the supply channels 14, the recovery channels 15, the first common supply channels 17, and the first common recovery channels 18 are all substantially perpendicular to the front surface of the first channel layer 22. Therefore, when the ink channels are densely formed with high efficiency, the ink circulation flow can be efficiently generated inside the pressure chambers 13 and the ejection ports 11 densely formed in the first channel layer 22.

(relationship (1) between the first common supply path 17 and the first common recovery path 18.)

The first common supply passage 17 and the first common recovery passage 18 are formed as follows.

As shown in fig. 6A and 6B, a gap (beam width) between the downstream end portion of the first common supply passage 17 and the upstream end portion of the second common recovery passage 18 is denoted by W1, and a distance between the supply passage 14 and the recovery passage 15 is denoted by W2. Further, a channel resistance per unit length from the downstream end portion of the supply channel 14 to the upstream end portion of the recovery channel 15 through the channel 10, the pressure chambers 13, and the channel 10 is denoted by R, and a flow rate of the ink circulation flow generated inside each pressure chamber 13 is denoted by Q1. The channel resistance R is expressed by an equation including a term (including a time element) representing the viscosity of the ink. Further, the maximum negative pressure inside the pressure chamber 13 within a range in which the ink meniscus in the ejection port 11 does not collapse is represented by Pmax, in addition to the maximum negative pressure inside the pressure chamber 13 within a range in which the ink can be appropriately ejected from the ejection port 11. These elements have the relationship of equation (1). The correlation equation (1) will be described below.

W2< (2X Pmax)/(Q1X R) equation (1)

In the case where the meniscus is depressed by the influence of the negative pressure as shown in fig. 8A and the meniscus is broken as the negative pressure increases as shown in fig. 8B, the ink does not exist on the ejection energy generating elements 12, and therefore the ink cannot be easily ejected under normal conditions. In the case where the surface tension of the ink is 30mN/m and 20mN/m, the aperture of the ejection orifice 11 and the allowable pressure limit in the ejection orifice 11 have the relationship shown in fig. 8C. In general, the ink meniscus in the ejection orifice depends on the ejection orifice aperture and the surface tension of the ink. However, when a pressure above-1000 mmAq is not maintained, the meniscus breaks. Therefore, as an example, in the case where the orifice diameter is 12 μm and the surface tension of the ink is 30mN/m, the maximum negative pressure in a range not to break the meniscus is-1000 mmAq. Further, even in a case where the meniscus is in a range not to be broken, the ink ejection amount is reduced by the meniscus being depressed as shown in fig. 8A. Therefore, the ink ejection state is affected, so that a plurality of sub-droplets (satellite droplets) of ink are generated.

Here, the appropriate ink ejection state refers to a state in which ink is satisfactorily ejected to the extent that no deformation of the printed image is visually recognized. In particular, it is desirable to adopt an ink ejection state in which the variation in the ink ejection amount is small and is not visually recognized. Further, in the case where the ink main droplets and the sub droplets (satellite droplets) are generated during the ink ejection operation, an ink ejection state in which at least a part of the ink sub dots formed by the satellite droplets contact the ink main dots formed by the main droplets and land on the printing medium is desirable.

In this way, the maximum negative pressure Pmax represents a negative pressure in which, when the pressure becomes higher than the maximum negative pressure, the meniscus is broken or ink cannot be ejected properly. Further, when satellite drops are generated, it is desirable that the satellite drops land on the print medium so that the sub dots are located within the main dots. For example, the maximum negative pressure Pmax is 500 mmAq. Further, the ink circulation flow rate Q1 is a flow rate capable of suppressing a decrease in the ink ejection speed and suppressing a change in the ink color density. That is, the flow rate can suppress the possibility that the ink ejection speed is lowered and the ink landing position is changed to a recognizable degree due to evaporation of moisture of the ink from the ejection opening 11. Further, the flow rate can suppress the possibility that the ink color density changes and the printed image becomes recognizable as unevenness due to evaporation of moisture of the ink from the ejection opening 11. For example, the ink circulation flow rate Q1 indicates that it is possible to suppress a decrease in the ink ejection speed within a range of 10% of the normal ejection state. In the experimental example, the ink circulation flow rate can be converted to a flow velocity of 0.05m/s or more in the pressure chamber 13. In other experimental examples, the flow rate was 0.1 m/s.

When the relationship of equation (1) is satisfied, the pressure inside the first common supply passage 17 can be maintained at a negative pressure. In an inkjet printhead, it is desirable that the pressure inside the channels of the printhead be maintained at a negative pressure. In the case where the pressure is positive, the following possibility occurs. That is, in the case where the pressure inside the ink passage of the print head is a positive pressure, ink is liable to leak from the members of the print head. Further, the ink is liable to leak from the ejection ports 11. For example, even if the pressure inside the first common supply passage 17 is a positive pressure and the pressure inside the pressure chamber 13 is maintained at a negative pressure due to a pressure loss caused by the ink circulation flow in the ink circulation state, there is a fear that the pressure loss varies due to the ink circulation flow variation and the pressure inside the pressure chamber 13 may become a positive pressure. As an extreme example, when the ink circulation flow is stopped, the pressure of the pressure chamber 13 becomes a positive pressure as in the first common supply passage. In order to prevent the pressure inside the pressure chamber 13 from becoming positive, complicated control needs to be applied to the ink supply system.

(description of the related equation (1))

Next, equation (1) for maintaining the pressure of the first common passage 17 at a negative pressure will be described in detail.

The pressure difference Δ P between the supply passage 14 and the recovery passage 15 is expressed by equation (2).

△ equation (2) Q1 XR XW 2

Further, in the case where the pressure of the supply passage 14 is represented by Pin and the pressure of the recovery passage 15 is represented by Pout, equation (3) is established. Further, in the case where the injection port 11 is located at an intermediate position between the supply passage 14 and the recovery passage 15, the pressure Pn of the injection port 11 is expressed by equation (4).

△ P-Pin-Pout. equation (3)

Pn ═ 2 · (Pin + Pout) · (equation 4)

Equation (5) is established from equations (3) and (4).

Pin + (△ P/2. equation (5)

In order to maintain the pressure of the first common supply passage 17 at a negative pressure, equation (6) needs to be satisfied.

Pin & lt + & gt (△ P/2) <0 & lt & gtequation (6)

Equation (6) can be modified to equation (7).

-Pn > △ P/2. equation (7)

Since the equation of Pn > -PMAX needs to be satisfied in order to normally eject ink, equation (8) is established

Pmax > △ P/2. equation (8)

From equations (2) and (8), equation (1) above can be derived.

Further, W1 and W2 have the relationship of equation (9).

W1< W2. equation (9)

Equation (10) is established from equation (9).

W1< (2 x Pmax)/(Q1 x R) · equation (10)

When the gap W1 is set so as to satisfy the relationship of equation (10), the pressure of the first common supply channel 17 can be maintained at a negative pressure, and therefore the reliability of the substrate and the print head can be improved.

In particular, in the print head in which the channel resistance of the pressure chamber 13 is high, the gap (beam width) W1 needs to be further reduced. In the print head employing the piezoelectric element as the ejection energy generating element 12, since the channel resistance of the pressure chamber 13 is generally decreased, the gap W1 can be increased. On the other hand, in the print head employing the heater as the ejection energy generating element 12, since the channel resistance of the pressure chamber 13 is generally increased, it is necessary to further reduce the gap W1.

(relationship (2) between the first common supply path 17 and the first common recovery path 18)

In the case where the maximum ejection amount of the ink ejected from the ejection ports 11 is represented by Q2, it is desirable to set the first common supply passage 17 and the first common recovery passage 18 so as to satisfy the relationship of equation (11).

W1< (2 x Pmax)/(Q2 x R) · equation (11)

When the ink circulation flow rate Q1 is set to be larger than the maximum ejection amount Q2, the occurrence of reverse flow of the ink circulation flow can be suppressed even when the ink ejection is maximized. In the case where the ink circulation flow reverse flow is generated, the heat generated by the ink ejection cannot be discharged by the ink circulation flow. Further, the ink may be excessively heated by the reverse flow of the discharge heat, and an ink ejection failure may occur due to the reverse flow of the precipitate inside the ink channel. However, since the occurrence of the reverse flow of the ink circulation flow is suppressed, the above state can be suppressed.

When the first common supply passage 17 and the first common recovery passage 18 are set to satisfy the relationship of equation (11), the pressure inside the first common supply passage 17 can be maintained at a negative pressure while suppressing occurrence of a reverse flow of the ink circulation flow. As a result, the reliability of the substrate and the print head can be improved.

As a result of the experiment, when the height of the pressure chamber 13 was set to 20 μm, the viscosity of the ink was set to 10cP, and the beam width W1 was set to 200 μm or less, the pressure inside the first common supply channel 17 was maintained at a negative pressure even when the flow rate of the ink circulation flow was 0.1m/s in order to suppress the occurrence of the reverse flow of the ink circulation flow. Further, when the beam width W is set to 100 μm or less, even when 10pl of ink is ejected at an ejection frequency of 30kHz (drive frequency of the print head), the pressure inside the first common supply channel 17 can be kept at a negative pressure while suppressing the reverse flow of the ink circulation flow.

(arrangement relationship between

passages

17 and 14 and arrangement relationship between passages 18 and 15)

Further, the arrangement relationship between the first common supply passage 17 and the supply passage 14 and the arrangement relationship between the first common recovery passage 18 and the recovery passage 15 may be set in the following manner. That is, as shown in fig. 6B, the center L1 of the supply passage 14 in the second direction is set at a position close to the ejection port 11 with respect to the center L2 of the first common supply passage 17 in the second direction. Similarly, the center L3 of the recovery passage 15 in the second direction is set at a position close to the ejection port 11 with respect to the center L4 of the first common recovery passage 18 in the second direction. In this way, when the supply passage 14 and the recovery passage 15 are provided close to the ejection port 11, the width W2 can be set smaller even if the same beam width W1 is set, and therefore the pressure inside the ejection port 11 can be easily maintained at an appropriate pressure.

(arrangement relationship between the passage 17 and the passage 18)

It is desirable to set the arrangement relationship between the first common supply passage 17 and the first common recovery passage 18 in the following manner.

That is, as shown in fig. 9, in the case where the beam width between the first common supply passage 17 and the first common recovery passage 18 located between the adjacent ejection port arrays 16 is represented by W3, the beam width W3 is set larger than the beam width W1. When the beam width W3 is set to be large, the strength of the substrate can be improved. Fig. 9 is a schematic view showing the liquid ejection substrate when viewed from the back side in a state where the ejection ports 11 are seen through. In this way, the first common supply passage 17 and the first common recovery passage 18 communicating with the same ejection port array 16 are formed close to each other, so that the beam width W1 is set small. On the other hand, the first common supply passage 17 communicating with one ejection port array 16 of the adjacent ejection port arrays 16 and the first common recovery passage 18 communicating with the other ejection port array are separated from each other so that the beam width W3 is large. Therefore, the strength of the substrate can be improved while suppressing the reverse flow of the ink circulation flow so that the pressure inside the first common supply channel 17 is kept at a negative pressure.

(Structure (1) for suppressing ink circulation flow rate variation and pressure variation)

Further, in the embodiment, the following structure is provided to suppress the ink circulation flow rate variation and the pressure variation of each pressure chamber 13.

That is, as shown in fig. 1 and 2, the plurality of first supply ports 30 communicate with one first common supply passage 17. Similarly, a plurality of first recovery ports 31 communicate with one first common recovery channel 18. The first supply port 30 and the first recovery port 31 are arranged so that the ink circulation flow rate variation and the pressure variation of each pressure chamber 13 are within a range that does not affect the ink ejection characteristics. Specifically, the first supply ports 30 and the first recovery ports 31 are alternately arranged along the first direction in which the ejection port array 16 extends. Therefore, the gap between the first supply port 30 and the first recovery port 31 in the first direction can be further reduced. Therefore, even in the case where the widths of the first common supply passage 17 and the first common recovery passage 18 are both relatively narrow, it is possible to suppress the ink circulation flow rate variation and the pressure variation of each pressure chamber 13.

(Structure (2) for suppressing ink circulation flow rate variation and pressure variation)

Further, in the embodiment, a structure is provided below to suppress the ink circulation flow rate variation and the pressure variation of each pressure chamber 13.

That is, as shown in fig. 1 and 2, the second common supply passage 32 extends in the second direction, and communicates with the plurality of first supply ports 30 arranged in the second direction. Similarly, the second common recovery channel 33 extends along the second direction, and communicates with the plurality of first recovery ports 31 arranged along the second direction. Further, the plurality of second common supply passages 32 are communicated together with one third common supply passage 36 through the second supply port 34. Similarly, the plurality of second common recovery passages 33 are communicated together with one third common recovery passage 37 through the second recovery ports 35.

When the ink passages communicate with each other through the six-layer structure in this way, the plurality of first common supply passages 17 eventually merge into one third common supply passage 36 through the plurality of first supply ports 30, and the plurality of first common supply passages 17 are formed at narrow intervals to match the plurality of ejection port arrays 16 arranged densely. Similarly, the plurality of first common recovery passages 18 are finally merged to one third common recovery passage 37 by the plurality of first recovery ports, and the plurality of first common recovery passages 18 are formed at narrow intervals to match the plurality of ejection port arrays 16 arranged densely. Therefore, the plurality of ejection port arrays 16 can be densely arranged without widening the respective passage widths of the first common supply passage 17 and the first common recovery passage 18. Further, it is possible to suppress ink circulation flow rate variation and pressure variation in each pressure chamber 13 corresponding to each ejection opening 11 in the plurality of ejection opening arrays 16 densely arranged in the above-described manner. Further, it is possible to supply ink from an ink tank (not shown) and recover the ink into the ink tank while suppressing ink circulation flow rate variation and pressure variation in the pressure chamber 13 with respect to the ejection ports 11 densely arranged. Therefore, not only the print head and the printing apparatus including the print head but also various liquid ejection heads and liquid ejection apparatuses including the liquid ejection heads can be provided in a compact size.

(Structure (3) for suppressing ink circulation flow rate variation and pressure variation)

Further, in order to suppress the ink circulation flow rate variation and the pressure variation of each pressure chamber 13, the following structure is desirable.

That is, the first supply port 30 and/or the first recovery port 31 at both end portions of the ejection port array 16 are formed smaller than the first supply port 30 and/or the first recovery port 31 at other positions than both end portions. That is, the opening of the first supply port 30 and/or the opening of the first recovery port 31 of the former is formed smaller than the opening of the first supply port 30 and/or the opening of the first recovery port 31 of the latter. In the vicinity of the first supply ports 30 located at both ends of the ejection port array 16, the ejection ports 11 in the ejection port array 16 are located only on one side in the first direction of the first supply ports 30 located at both ends of the ejection port array 16. Therefore, the ink flow rate of the first supply ports 30 located at both ends of the ejection port array 16 is smaller than the ink flow rate of the other first supply ports 30. Similarly, in the vicinity of the first recovery ports 31 located at both ends of the ejection port array 16, the ejection ports 11 in the ejection port array 16 are located only on one side in the first direction of the first recovery ports 31 located at both ends of the ejection port array 16. Therefore, the ink flow amount of the first recovery ports 31 located at both ends of the ejection port array 16 is smaller than the ink flow amount of the other first recovery ports 31.

In this way, the first supply port 30 and/or the first recovery port 31 formed at both ends of the ejection port array 16 are formed in a small size in shape, so that the passage resistance increases. Therefore, the pressure loss generated in the first supply port 30 and/or the first recovery port 31 formed at both ends of the ejection port array 16 can be adjusted to be similar to the pressure loss generated in the other first supply port 30 and/or the first recovery port 31. Therefore, it is possible to reduce the difference between the ink flow rate flowing in the pressure chamber 13 through the first supply port 30 and/or the first recovery port 31 at both ends of the ejection port array 16 and the ink flow rate flowing in the pressure chamber 13 through the other first supply port 30 and/or the other first recovery port 31. As a result, the difference in the ink circulation flow rate inside each pressure chamber 13 can be further suppressed.

(Structure (4) for suppressing ink circulation flow rate variation and pressure variation)

That is, as shown in fig. 7(a), the region "a" between the end of the ejection orifice array 16 and the end of the liquid ejection substrate 100 is set to be large. For example, the region "a" may serve as an arrangement space where a driving circuit of the ejection energy generating element 12 is arranged and the connection pad 150 for transmitting an electric signal to the liquid ejection substrate 100 and receiving an electric signal from the liquid ejection substrate 100 is arranged. Further, it is desirable to arrange the first recovery port 31 by using the region "a" as in fig. 7(b) and (c) which are perspective views showing the liquid ejection substrate 100 when viewed from the ejection port 11. That is, along the first direction in which the ejection port array 16 extends, the first recovery port 31 is arranged to overlap the ejection ports 11 located at the ends of the ejection port array 16. In fig. 7(b), the left end of the first common recovery passage 18 and the left end of the first recovery port 31 are located at the same position. Further, in fig. 7(c), the left end of the first common recovery passage 18 and the left end of the first recovery port 31 protrude leftward largely with respect to the recovery passage 15 located at the left end.

In fig. 7(b) and (c), as indicated by an arrow a1, the ink passing through the pressure chamber 13 located at the end of the ejection port array 16 first flows from the first supply port 30 into the first common supply channel 17 and the supply channel 14. Then, as indicated by an arrow a2, the ink flows out from the first recovery port 31 after passing through the pressure chamber 13, the recovery passage 15, and the first common recovery passage 18 at the end of the ejection port array 16. Fig. 7(d) is a comparative example in the case where the first recovery port 31 is arranged so as not to overlap the ejection ports 11 located at the ends of the ejection port array 16 in the first direction. In fig. 7(d), as indicated by an arrow a1, the ink passing through the pressure chamber 13 located at the end of the ejection port array 16 first flows from the first supply port 30 into the first common supply channel 17 and the supply channel 14. Then, the ink passes through the pressure chamber 13 and the recovery passage 15 at the end of the ejection port array 16 as indicated by an arrow a2, and flows out from the first recovery port 31 after passing through the first common recovery passage 18 as indicated by an arrow A3.

In fig. 7(b) and (c), the length of the ink passage of the ink flowing from the first supply port 30 located at the first direction end and flowing out of the first recovery port 31 via the pressure chamber 30 can be shortened, as compared with the configuration of fig. 7 (d). That is, since the maximum pressure loss in the first common supply passage 17 and the first common recovery passage 18 located near the end of the ejection port array 16 is reduced, the ink circulation flow rate variation inside each pressure chamber 13 can be suppressed. Further, in the case where the first supply port 30 is located at the first-direction end instead of the first recovery port 31, the first supply port 30 may be arranged to overlap the ejection ports 11 located at the end of the ejection port array 16 in the first direction.

(temperature distribution suppressing structure)

In an embodiment, the following structure is provided to suppress temperature distribution within the print head.

That is, as shown in fig. 1 and 2, the first recovery ports 31 are arranged at both end portions of the ejection port array 16. In the case where the ink is forcibly circulated through each pressure chamber 13 as in this example, the heat generated by the ejection energy generating elements 12 and the like is recovered by the ink. Therefore, the ink temperature inside the ink recovery-side passage is higher than the ink temperature inside each pressure chamber 13.

Further, even if a sufficient ink circulation flow rate is secured in order to suppress the influence caused by the evaporation of moisture in the ink from the ejection openings 11, there is a case where the ejection amount of the ink ejected from the plurality of ejection openings 11 at the same time becomes larger than the ink circulation flow rate. In this case, ink is also supplied from the second common recovery passage 37 into the pressure chamber 13. That is, the ink is supplied from the second common recovery passage 37 into the pressure chamber 13 through the second recovery port 35, the second common recovery passage 33, the first recovery port 31, the first common recovery passage 18, and the recovery passage 15. Therefore, there is a case where the high-temperature ink inside the first recovery port 31 is supplied into the pressure chamber 13 when ink is ejected from the plurality of ejection ports 11 at the same time. In this case, since the ink temperature in the vicinity of the first recovery port becomes higher than the ink temperature in the vicinity of the first supply port 30, there is a fear that an ink ejection speed difference is generated between the ejection ports 11 in the vicinity of the first supply port 30 and the ejection ports 11 in the vicinity of the first recovery port 31. Further, in the case where the first supply port 30 is located on one end side of the two end portions of the ejection port array 16 and the first recovery port 31 is located on the other end side, the temperature distribution inclination along the ejection port 11 arrangement direction occurs in the entire ejection port array 16, and thus the temperature distribution width in the entire print head increases. As a result, there is a fear that ink ejection characteristic variation occurs in each ejection port 11.

In this embodiment, since the first recovery ports 31 are arranged at both end portions of the ejection port array 16, the temperature distribution inclination is suppressed, and therefore, the ink ejection characteristics can be suppressed from varying. Further, even when the first supply ports 30 are arranged at both end portions of the ejection port array 16, the same effect can be obtained. However, as in this embodiment, it is desirable to arrange the first recovery ports 31 at both ends of the ejection port array 16.

That is, in the liquid ejection substrate 100, as described above, the region "a" where the ejection ports 11 are not arranged is set approximately between both end portions of the ejection port array 16 and the end portion of the liquid ejection substrate 100, and thus heat generated by the ink ejection operation is radiated from the region "a". Therefore, in the case where the plurality of ejection openings 11 eject ink, there is a tendency that the temperature values of both end portions of the ejection opening array 16 become lower than those of other portions. Since the first recovery ports 31 are arranged at both end portions of the ejection port array 16, it is possible to supply the high-temperature ink to both end portions of the ejection port array 16 in this case. Therefore, since the temperature values of both end portions of the ejection port array 16 are set higher, the temperature difference with respect to the other portion can be reduced. As a result, since the temperature distribution width in the entire print head is reduced, it is possible to suppress the ink ejection characteristics from varying.

Fig. 10 is a flowchart showing an example of the manufacturing steps of the liquid ejection head of the present embodiment.

First, a nozzle is formed on the liquid ejection substrate 100 by the nozzle forming step S1, and the ejection energy generating element 12 and a desired circuit are formed on the liquid ejection substrate 100. The nozzle is a portion that ejects ink by using the ejection energy generating element 12, and includes an ejection port 11 and a pressure chamber 13. Then, the first common supply path 17 and the first common recovery path 18 are formed on the back surface of the liquid ejection substrate 100 by the back surface supply path forming step S2. Next, the cap member forming step S3 forms the cap plate 20 (cap member) or 2020 of the embodiment shown in fig. 36C or fig. 45C on the back surface of the liquid ejection substrate 100. Then, the shape of the liquid ejection substrate 100 is processed from a wafer shape into a chip shape by the dicing step S4. Then, the liquid ejection substrate 100 is bonded to the support member 400 and the first passage member 500 of the embodiment of fig. 24A to 24E by the bonding step S5.

In this way, since the cap plate as the third channel layer is formed on the back surface of the liquid ejection substrate 100 by the cap member forming step S3 before the bonding step S5, the first supply port 30 and the first recovery port 31 can be formed in the wafer-shaped liquid ejection substrate 100. Since the cover plate is processed when the liquid ejection substrate 100 has a wafer shape, the processing accuracy is improved compared to machining or molding, and therefore, the minute holes can be formed with higher accuracy. Further, the cover plate can be formed thinner. Therefore, the ejection ports 11 can be arranged with higher accuracy. Further, since the channel resistances of the first supply port 30 and the first recovery port 31 are reduced with little variation, the pressure difference for generating the ink circulation flow can be stabilized, and thus the circulation flow rate can be suppressed to be small.

The cover plate may be formed from a silicon substrate. That is, since the cap plate formed as a wafer-shaped silicon substrate is bonded to the wafer-shaped liquid ejection substrate 100, the number of steps can be reduced as compared with the case where the cap plate is bonded to the chip-shaped liquid ejection substrate 100. Further, the cover plate may be formed of a resin film. As in the case of the silicon substrate, since the cap plate can be bonded so that the film-like resin is laminated on the wafer-like liquid ejection substrate 100, the number of steps can be reduced as compared with the case where the cap plate is bonded to each chip-like liquid ejection substrate 100.

The order and content of the steps of fig. 10 are merely exemplary, and not restrictive of the invention. For example, the order of the nozzle forming step S1, the back supply path forming step S2, the cover member forming step S3, and the cutting step S4 is not limited to the example of fig. 10 as long as the cover member forming step S3 can be carried out before the joining step S5.

(second embodiment)

Fig. 11 and 12 are explanatory views showing a liquid ejection unit 300 according to a second embodiment of the present invention, and the same description as the above-described embodiment will be omitted, and the same reference numerals will be given to the same description as the above-described embodiment. Fig. 11 is an exploded perspective view showing the liquid ejection unit 300, and fig. 12 is an exploded top view showing the liquid ejection unit 300.

In this embodiment, the first common supply passage 17 and the second common supply passage 32 communicate with each other at one end side of the ejection port array 16, and the first common recovery passage 18 and the second common recovery passage 33 communicate with each other at the other end side. In this embodiment, since the third channel layer 24 of the first embodiment is not provided and the first recovery port 31 of the first embodiment can be omitted, the structure of the channel can be simplified.

(third embodiment)

Fig. 13 and 14 are explanatory views showing a third embodiment according to the present invention, and the same description as the above-described embodiment will be omitted, and the same reference numerals will be given to the same description as the above-described embodiment. Fig. 13 is an exploded perspective view showing the liquid ejection unit 300, and fig. 14 is an exploded top view showing the liquid ejection unit 300.

In this embodiment, at one end side of the ejection port array 16, the first common supply passage 17 and the first supply port 30 communicate with each other and the first common recovery passage 18 and the first recovery port 31 communicate with each other. Similarly, at the other end side of the ejection port array 16, the first common supply passage 17 and the first supply port 30 communicate with each other and the first common recovery passage 18 and the first recovery port 31 communicate with each other. When the first supply port 30 and the first recovery port 31 are arranged at both end portions of the ejection port array 16, it is possible to suppress a pressure variation inside each pressure chamber 13 and an ink circulation flow rate variation along the first direction in which the ejection port array 16 extends, compared to the second embodiment. Further, the second common supply passage 32 and the second common recovery passage 33 may be both arranged at two positions.

In this way, in this embodiment, since the number of the first supply ports 30 and the number of the first recovery ports 31 are reduced, the structure of the ink passage can be simplified.

(fourth embodiment)

Fig. 15 to 18B are explanatory views showing a liquid ejection unit 300 according to a fourth embodiment of the present invention, and the same description as the above-described embodiment will be omitted, and the same reference numerals will be given to the same description as the above-described embodiment. Fig. 15 is an exploded perspective view showing the liquid ejection unit 300, and fig. 16 is an exploded top view showing the liquid ejection unit 300. In this embodiment, the planar shape of the liquid ejection unit 300 is formed into a parallelogram (a parallelogram in which adjacent sides are at non-right angles), but for the sake of simplifying the description, the planar shape is shown as a rectangular shape. Fig. 17A is a plan view showing the liquid ejection substrate 100 according to the embodiment, and fig. 17B is a perspective view showing an end structure of the ejection port array 16.

As shown in fig. 17A, the planar shape of the liquid ejection substrate 100 of this embodiment is formed into a parallelogram shape, and the area "a" between the end of the ejection port array 16 and the end of the element plate is smaller than the area "a" of the liquid ejection substrate 100 of fig. 7(a) of the first embodiment. In this embodiment, as shown in fig. 17A, the connection pads 150 for transmitting and receiving electric signals between the liquid ejection substrate 100 and the outside and the drive circuit for ejecting the energy elements 12 and the like are arranged on the long side of the liquid ejection substrate 100. In the case of obtaining an elongated print head (line head) by combining the liquid ejection substrates 100, the liquid ejection substrates 100 may be arranged in a zigzag shape, instead of a substantially linear shape, as shown in fig. 17A. With this arrangement, the end portions of the ejection port arrays 16 of two adjacent liquid ejection substrates 100 can easily overlap each other in the second direction, as shown in fig. 17A. Here, "arranged substantially in a line" denotes a state in which two adjacent liquid ejection substrates 100 partially overlap each other in both the first direction and the second direction.

In this way, in this embodiment, the ejection port 11 is arranged to the vicinity of the end of the liquid ejection substrate 100. In this embodiment, it is difficult to arrange the first supply port 30 or the first recovery port 31 at a position overlapping with the end of the ejection port array 16 of the liquid ejection substrate 100 as shown in fig. 7(b) and (c) of the first embodiment. Therefore, in this embodiment, the first supply port 30 or the first recovery port 31 is arranged at a position shifted to the center with respect to the end of the ejection port array 16, as shown in fig. 17B.

In this embodiment, in order to suppress variations in the ink circulation flow rate and pressure variations in each pressure chamber 13 and in order to suppress the temperature distribution inside the liquid ejection substrate 100, the first supply ports 30 are arranged in the vicinity of both end portions of the ejection port array 16, as shown in fig. 15 and 16.

As in this embodiment, in the case where the first supply port 30 is arranged near the end of the ejection port array 16, the pressure difference between the first common supply passage 17 and the first common recovery passage 18 located at the end of the ejection port array 16 during the ink ejection operation is larger than in the case where the ink circulation operation is performed using the initial pressure difference. On the other hand, as in the first embodiment, in the case where the first recovery port 31 is arranged at the end of the ejection port array 16, the pressure difference between the first common supply passage 17 and the first common recovery passage 18 at the end of the ejection port array 16 during the ink ejection operation is smaller than in the case where the ink circulation operation is performed using the initial pressure difference. When the pressure difference between the first common supply passage 17 and the first common recovery passage 18 decreases, the ink circulation flow rate decreases. Therefore, the effect of suppressing the influence due to the evaporation of the ink from the ejection openings 11 is reduced. That is, the effect of suppressing the decrease in the ink ejection speed and the change in the ink color density is reduced. Therefore, the differential pressure is preferably set to be large. As in this embodiment, since the first supply ports 30 are arranged in the vicinity of both end portions of the ejection port array 16, the influence of the variation in the ink circulation flow rate can be reduced.

Since the pressure inside the first supply port 30 is set higher than the pressure inside the first recovery port 31 to generate the ink circulation flow, it is easy to supply the ink into the pressure chamber 13 through the first supply port 30 during the ink ejection operation. In this way, since the first supply port 30 that easily supplies ink is arranged in the vicinity of the end of the ejection port array 16, it is possible to reduce the pressure loss between the first common supply passage 17 and the first common recovery passage 18 when ejecting ink from the plurality of ejection ports 11 at the same time.

Further, in this embodiment, as described above, since the area "a" between the end of the ejection port array 16 and the end of the element plate is small, the degree of heat generated by the ink ejection operation is small emitted from the area "a". Since the area "a" is small, the length of the portion of the first common supply passage 17 from the first supply port 30 to the end of the ejection port array 16 increases as shown in fig. 17B. Similarly, the length of the portion of the first common recovery passage 18 from the first recovery port 31 to the end of the ejection port array 16 increases. Therefore, the ink passing through the portion of the first common supply passage 17 and the portion of the first common recovery passage 18 easily receives heat from the liquid ejection substrate 100. Therefore, when ink is ejected from the plurality of ejection openings 11 at the same time, there is a tendency that the temperature of the end portion of the ejection opening array 16 is higher than that of the other portion. Further, a pressure loss generated in each ink channel during an ink ejection operation increases, and thus the pressure at the end of the ejection port array 16 becomes uneven.

However, in this embodiment, as described above, since the first supply ports 30 are arranged at both end portions of the ejection port array 16, a large amount of ink is supplied from the first supply ports 30 arranged in the vicinity of the end portions of the ejection port array 16 to the ejection ports 11 in the vicinity of the end portions of the ejection port array 16. As a result, when ink is ejected from the plurality of ejection openings 11 at the same time, the amount of high-temperature ink supplied from the first supply port 30 can be reduced, and therefore the temperature rise at the end of the ejection opening array 16 can be reduced.

Specifically, the ink supplied from the first supply port 30 first flows into the supply passage 14 from the first common supply passage 17, as indicated by an arrow B1 in fig. 17B. Then, the ink passes through the pressure chamber 13 and the recovery passage 15 at the end of the ejection port array 16 as indicated by arrow B2, and flows out from the first recovery port 31 through the first common recovery passage 18 as indicated by arrow B3.

In this way, in this embodiment, since the first supply ports 30 are arranged at both end portions of the ejection port array 16, the ink circulation flow rate and the pressure variation can be suppressed and the temperature distribution inside the print head can be suppressed to be small. Therefore, it is possible to print a high-quality image with high accuracy by suppressing a decrease in the ink ejection speed, a change in the ink color density, and a change in the ejection characteristics caused by evaporation of the ink moisture from the ejection openings 11. Further, it is desirable that the first common supply passage 17 and the first common recovery passage 18 of this embodiment have the shapes shown in fig. 18B. Fig. 18A is a diagram showing the liquid ejection substrate when viewed from the back surface side, and fig. 18B is an enlarged view showing the end of the first common supply passage 17 and the end of the first common recovery passage 18 along the longitudinal direction of fig. 18A. Both end portions in the longitudinal direction of the first common supply passage 17 and the first common recovery passage 18 communicating with the same ejection port array 16 are provided at the same position shown in fig. 18B. Further, as shown in fig. 18A, in two ejection port arrays 16 disposed parallel to each other and adjacent to each other, the first common supply passage 17 and the first common supply recovery passage 18 at one side of the adjacent ejection port array 16 and the first common supply passage 17 and the first common recovery passage 18 at the other side of the adjacent ejection port array 16 have the following positional relationship. That is, both longitudinal ends of the first common supply passage 17 and the first common recovery passage 18 communicating with one side of the adjacent ejection port array 16 and both ends of the first common supply passage 17 and the first common recovery passage 18 communicating with the other side are obliquely offset from each other.

By the

channels

17 and 18 having such a shape, the width between both end portions of the

channels

17 and 18 and the end portion of the liquid ejection substrate 100 is widened to ensure the strength of the liquid ejection substrate 100 while reliably supplying ink to the ejection ports 11 located at both end portions of the ejection port array 16. More specifically, as shown in fig. 18A, the distance between the right end of the channel 17 and the right end of the liquid ejection substrate 100 may be set to be longer, and the distance between the left end of the channel 18 and the left end of the liquid ejection substrate 100 may be set to be longer. Further, as shown in fig. 18B, both end portions in the longitudinal direction of the first common supply passage 17 and the first common recovery passage 18 are formed in a shape with corners removed. In the case of this example, a chamfered shape is shown, but a rounded shape may also be used. With this shape, it is possible to suppress the possibility of stress concentration on both ends of the first common supply passage 17 and the first common recovery passage 18 when an external force or strain is generated due to heat, and thus to suppress damage of the liquid ejection substrate 100 due to cracking or the like.

(fifth embodiment)

Fig. 19 and 20 are explanatory views showing a liquid ejection unit 300 according to a fifth embodiment of the present invention, and the same description as the above-described embodiment will be omitted, and the same reference numerals will be given to the same description as the above-described embodiment. Fig. 19 is an exploded perspective view showing the liquid ejection unit 300, and fig. 20 is an exploded top view showing the liquid ejection unit 300.

In this example, as shown in fig. 19, three first common supply passages 17(17A, 17B, and 17C) and two first common recovery passages 18(18A and 18B) are arranged with respect to the four ejection port arrays 16(16A, 16B, 16C, and 16D). As shown in fig. 20, a recovery passage 15 common to the

arrays

16A and 16B is arranged between the

ejection port arrays

16A and 16B, and the recovery passage 15 communicates with a first common recovery passage 18A. Further, a supply passage 14 common to the

arrays

16B and 16C is arranged between the

ejection port arrays

16B and 16C, and the supply passage 14 communicates with a first common supply passage 17A. Further, a recovery passage 15 common to the

arrays

16C and 16D is arranged between the

ejection port arrays

16C and 16D, and the recovery passage 15 communicates with a first common recovery passage 18B. The supply passage 14 of the ejection port array 16A communicates with the first common supply passage 17A, and the supply passage 14 of the ejection port array 16D communicates with the first common supply passage 17C.

In this way, one first common supply passage 17B communicates with the pressure chambers 13 of the ejection port array 16B through the supply passage 14 common to the

arrays

16B and 16C. Further, one supply recovery passage 18A communicates with the pressure chambers 13 of the

ejection port arrays

16A and 16B through the recovery passage 15 common to the

arrays

16A and 16B. Similarly, one first common recovery passage 18B communicates with the pressure chambers 13 of the

ejection port arrays

16C and 16D through the recovery passage 15 common to the

arrays

16C and 16D.

According to this embodiment, in addition to the effects of the above-described embodiment, the following effects can be obtained.

That is, since two adjacent ejection port arrays share the first common supply channel 17 and the first common recovery channel 18, the number of partition walls between the ink channels and the number of ink channels can be reduced. Therefore, the gap between the ejection port arrays 16 can be narrowed, and the width between the ink channels can be increased. As a result, the ink circulation flow rate variation and the pressure variation of each pressure chamber 13 can be further suppressed. Then, the ejection port arrays 16 are arranged more densely than in the above-described embodiment, so that the sizes of the substrate and the print head can be reduced. Further, in the case where the arrangement density of the ejection port arrays 16 is the same, the ink circulation flow rate variation and the pressure variation of each pressure chamber 13 are further suppressed, and the number of the first supply ports 30 and the number of the first recovery ports 31 can be reduced. Therefore, the structure of the ink channel of the substrate can be simplified.

(sixth embodiment)

Fig. 21 to 23 are explanatory views showing a liquid ejection unit 300 according to a sixth embodiment of the present invention, and the same description as the above-described embodiment will be omitted, and the same reference numerals will be given to the same description as the above-described embodiment. Fig. 21 is an exploded perspective view showing the liquid ejection unit 300, and fig. 22 is an exploded top view showing the liquid ejection unit 300.

In this embodiment, an ejection orifice array having the ejection orifices 51 for the first ink and an ejection orifice array having the ejection orifices 61 for the second ink are formed into one substrate to eject inks of different colors or kinds of inks. The second channel layer 23 is provided with a first common supply channel 52 for the first ink, a first common supply channel 62 for the second ink, a first common recovery channel 53 for the first ink, and a first common recovery channel 63 for the second ink. The third channel layer 24 is provided with a supply port 54 for the first ink, a supply port 64 for the second ink, a recovery port 55 for the first ink, and a recovery port 65 for the second ink. The fourth channel layer 25 is provided with a second common supply channel 56 for the first ink, a second common supply channel 66 for the second ink, a third common recovery channel 57 for the first ink, and a third common recovery channel 67 for the second ink. The fifth channel layer 26 is provided with a second supply port 58 for the first ink, a second supply port 68 for the second ink, a second recovery port 59 for the first ink, and a second recovery port 69 for the second ink. The sixth channel layer 27 is provided with a third common supply channel 70 for the first ink, a third common supply channel 80 for the second ink, a third common recovery channel 71 for the first ink, and a third common recovery channel 81 for the second ink.

Similarly to the first embodiment, the first and second inks are supplied from the third

common supply passages

70 and 80, respectively, pass through the corresponding pressure chambers 13, and then flow out from the third

common recovery passages

71 and 81.

Similarly to the fifth embodiment, one first common supply passage may communicate with the pressure chambers of the two ejection port arrays. Similarly, one first common recovery passage may communicate with the pressure chambers of the two ejection port arrays. Further, the width of the sixth channel layer 27 in the second direction may be set larger than the width of the first channel layer 22 in the second direction.

In this way, even in a print head for plural color inks or plural kinds of inks, it is possible to suppress ink circulation flow rate variation and pressure variation in each pressure chamber without widening the width of the first common supply passage and the width of the first common recovery passage. Therefore, it is possible to print a high-quality image with high accuracy by suppressing a decrease in the ink ejection speed and a change in the ink color density due to evaporation of moisture in the ink from the ejection openings.

(arrangement relationship between the

passages

52 and 53 and the passages 62 and 63)

It is desirable to set the arrangement relationship between the first common supply passage 52 and the first common recovery passage 53 for the first ink and the first common supply passage 62 and the first common recovery passage 63 for the second ink in the following manner.

That is, as shown in fig. 23, the beam width W4 between the first common recovery channel 53 and the first common supply channel 62 between the ejection port array 16(1) for the first ink and the ejection port array 16(2) for the second ink is set larger than the beam width W1. When the beam width W4 is set to be large, ink leakage between the first common recovery passage 53 and the first common supply passage 62 can be suppressed so that the ink colors do not mix with each other. The beam width W3 and the beam width W4 may be equal to or different from each other. In particular, in the case where the beam width W3 between channels for the same ink is set smaller than the beam width W4 between channels for different inks, the pressure loss of the channels for ink flow is reduced, and therefore the ink ejection characteristics can be improved. In this way, since the reverse flow of the ink circulation flow is suppressed, it is possible to suppress the ink colors from mixing with each other while keeping the pressure inside the first common supply channel 17 at the negative pressure.

(construction example of liquid Ejection head)

Fig. 24A to 24E are perspective views showing configuration examples having different ink jet print heads as the liquid ejection head of the present invention.

The printhead of fig. 24A includes one liquid ejection substrate 100, and the support member 400 and the liquid ejection substrate 100 are sequentially arranged on the first passage member 500. The print head is used in a so-called serial scan type inkjet printing apparatus. The printing apparatus prints an image on a printing medium by repeating a printing operation of ejecting ink from ejection ports while moving a print head in a main scanning direction indicated by an arrow X and a conveying operation of conveying the printing medium in a sub-scanning direction indicated by an arrow Y, the sub-scanning direction crossing (in this example being orthogonal to) the main scanning direction. The main scanning direction is a direction intersecting (orthogonal in this example) the first direction in which the ejection opening array 16 extends.

The print head of fig. 24B and 24C is an elongated line-type print head in which a plurality of liquid ejection substrates 100 are arranged in a zigzag shape. In the configuration of fig. 24B, the first channel member 500 is arranged to be shared by the plurality of liquid ejection substrates 100. In the configuration of fig. 24C, each liquid ejection substrate 100 is individually arranged with the first channel member 500. The first channel member 500 is disposed on the second channel member 600. Such a print head is used in a so-called full-line type inkjet printing apparatus. This kind of printing apparatus continuously prints images on a print medium by ejecting ink from the print head at a fixed position while continuously conveying the print medium in a direction indicated by an arrow Y, which intersects (in this example, is orthogonal to) a first direction in which the ejection port array 16 extends.

The print heads of fig. 24D and 24E are elongated line-type print heads and are used in a so-called full-line-type inkjet printing apparatus in which the liquid ejection substrates 100 are arranged in a row shape. In the configuration of fig. 24D, the first channel member 500 is arranged to be shared by the plurality of liquid ejection substrates 100. In the configuration of fig. 24E, each liquid ejection substrate 100 is individually arranged with the first channel member 500. The first channel member 500 is disposed on the second channel member 600. It is desirable that the liquid ejection substrate 100 of such a printhead be formed in the shape of the fourth embodiment.

In such various print heads, by generating the ink circulation flow as described above, it is possible to print a high-quality image with high accuracy while suppressing a decrease in the ink ejection speed and a change in the ink color density due to evaporation of moisture in the ink from the ejection openings.

(construction example of liquid ejecting apparatus)

Fig. 25A to 25C are diagrams showing configuration examples having different inkjet printing apparatuses to which the liquid ejection apparatus of the present invention is applied.

The inkjet printing apparatus of fig. 25A is a serial scan type printing apparatus that uses a print head having the configuration of fig. 24A as the print head 43. The frame 47 is formed of a plurality of plate-like metal members having a predetermined rigidity and constitutes a frame of the printing apparatus. The feeding unit 41, the conveying unit 42, and the carriage 46 equipped with the print head 43 and movable in the main scanning direction indicated by the arrow X are assembled into a frame 47. The main scanning direction is a direction intersecting (orthogonal in this example) the extending direction of the ejection port array in the print head 43. The feeding unit 41 automatically feeds sheet-like printing media (not illustrated) into the printing apparatus, and the conveying unit 42 conveys the printing media fed one by the feeding unit 41 in a sub-scanning direction indicated by an arrow Y. The sub-scanning direction is a direction intersecting (orthogonal in this example) the main scanning direction. Such a printing apparatus prints an image on a printing medium by repeating a printing operation of ejecting ink from ejection ports of the printing head 43 while moving the printing head 43 along the main scanning direction together with the carriage 46 and a conveying operation of conveying the printing medium along the sub-scanning direction. Ink is supplied to the print head 43 from an ink tank (not shown).

The inkjet printing apparatus of fig. 25B is a full-line type printing apparatus that uses the elongated print head 120 described in fig. 24B, 24C, and 24D and 24E and includes a conveying mechanism 202, and the conveying mechanism 202 continuously conveys a sheet (printing medium) 201 in a direction indicated by an arrow Y. As the conveying mechanism 202, instead of the structure using the conveying belt in this example, a structure using a conveying roller or the like may be used. In this example, four

print heads

120Y, 120M, 120C, and 120B that eject yellow (Y) ink, magenta (M) ink, cyan (C) ink, and Black (BK) ink are provided as the print head 120. Respective inks are supplied to the printheads (120Y, 120M, 120C, 120B). When ink is ejected from the print head 120 at a fixed position while the sheet 201 is continuously conveyed in the direction indicated by the arrow Y, a color image can be continuously printed on the sheet 201.

Fig. 25C is an explanatory diagram showing an ink supply system for the print heads 43 and 120. The ink inside the first ink tank 44 is supplied to the third common supply channel 36 of the

print head

43 or 120, passes through the pressure chamber 13, and is recovered from the third common recovery channel 37 into the second ink tank 45. As a method of generating the ink circulation flow inside the

print head

43 or 120, for example, a method of using a water head difference between the first ink tank 44 and the second ink tank 45 is known. Alternatively, a method is known in which a pressure difference is generated between the first ink tank 44 and the second ink tank 45 by controlling the pressure inside the first ink tank 44 and the pressure inside the second ink tank 45. Also, a method of generating an ink circulation flow by using a pump or the like is known. The configuration of the ink supply system and the method of generating the ink circulation flow are not limited to the present example and may be arbitrarily set. The specific configuration and method are not critical, so long as the differential pressure generator configured is capable of generating the differential pressure required to circulate ink within the pressure chamber.

In such a printing apparatus, by generating the ink circulation flow in the print head, it is possible to print a high-quality image with high accuracy while suppressing a decrease in the ink ejection speed and a change in the ink color density caused by evaporation of moisture in the ink from the ejection openings.

(first application example)

Fig. 26 to 38 are diagrams showing a first application example to which the present invention can be applied.

(description of ink jet printing apparatus)

Fig. 26 is a diagram showing a schematic configuration of a liquid ejection apparatus that ejects liquid in the present invention, particularly an inkjet printing apparatus (hereinafter referred to as a printing apparatus) 1000 that prints an image by inkjet. The printing apparatus 1000 includes: a conveying unit 1, the conveying unit 1 conveying a printing medium 2; and a line-type (wide-format) liquid ejection head 3, the liquid ejection head 3 being arranged substantially orthogonal to the conveying direction of the printing medium 2. Then, the printing apparatus 1000 is a line printing apparatus that continuously prints images in one pass by ejecting ink onto the relatively moving printing medium 2 while continuously or intermittently conveying the printing medium 2. The liquid ejection head 3 includes: a negative pressure control unit 230, the negative pressure control unit 230 controlling the pressure (negative pressure) inside the circulation path; a liquid supply unit 220, the liquid supply unit 220 communicating with the negative pressure control unit 230; a liquid connection portion 111, the liquid connection portion 111 serving as an ink supply port and an ink discharge port of the liquid supply unit 220; and a housing 380. The print medium 2 is not limited to cut paper, but may be a continuous roll medium. The liquid ejection head 3 is capable of printing a full-color image with cyan ink C, magenta ink M, yellow ink Y, and black ink K, and is fluidly connected to a liquid supply member, a main tank, and a buffer tank (see fig. 27 described below) as supply paths for supplying liquid to the liquid ejection head 3. Further, the control unit is electrically connected to the liquid ejection head 3 to supply electric power to the liquid ejection head 3 and transmit an ejection control signal. The liquid path and the electric signal path in the liquid ejection head 3 will be described below.

The printing apparatus 1000 is an inkjet printing apparatus so that liquid such as ink circulates between a tank described below and the liquid ejection head 3. The circulation pattern includes a first circulation pattern in which the liquid is circulated by activating two circulation pumps (a high-pressure pump and a low-pressure pump) at the downstream side of the liquid ejection head 3, and a second circulation pattern in which the liquid is circulated by activating two circulation pumps (a high-pressure pump and a low-pressure pump) at the upstream side of the liquid ejection head 3. Hereinafter, a first cycle pattern and a second cycle pattern of the cycle will be described.

(description of the first cycle type)

Fig. 27 is a schematic diagram showing a first circulation pattern in a circulation path suitable for the application example printing apparatus 1000. The liquid ejection head 3 is connected to a first circulation pump (high pressure side) 1001, a first circulation pump (low pressure side) 1002, and a buffer tank 1003 in fluid communication. Further, in fig. 27, for simplification of description, a path through which ink of one color of cyan C, magenta M, yellow Y, and black K flows is shown. However, actually, circulation paths for four color inks are provided in the liquid ejection head 3 and the printing apparatus main body.

In the first circulation pattern, the ink inside the main tank 1006 is supplied into the buffer tank 1003 by the replenishment pump 1005, and then is supplied to the liquid supply unit 220 of the liquid ejection head 3 via the liquid connection portion 111 by the second circulation pump 1004. Then, the ink adjusted to two different negative pressures (high pressure and low pressure) by the negative pressure control unit 230 connected to the liquid supply unit 220 is circulated into two channels having high pressure and low pressure. The ink inside the liquid ejection head 3 circulates in the liquid ejection head by the action of the first circulation pump 1001 (high pressure side) and the action of the first circulation pump 1002 (low pressure side) at the downstream side of the liquid ejection head 3, is discharged from the liquid ejection head 3 through the liquid connection portion 111, and returns to the buffer tank 1003.

The buffer tank 1003, which is a sub tank, is connected to the main tank 1006, and includes an atmospheric communication port (not shown) that communicates the inside of the tank 1003 with the outside, so that bubbles in the ink can be discharged to the outside. A make-up pump 1005 is provided between the surge tank 1003 and the main tank 1006. In the printing operation and in the suction recovery operation, the replenishment pump 1005 outputs the ink from the main tank 1006 to the buffer tank 1003 after the ink is consumed by ejecting the ink (ink discharge) from the ejection ports of the liquid ejection head 3.

Two first circulation pumps 1001 and 1002 suck the liquid from the liquid connection portion 111 of the liquid ejection head 3 so that the liquid flows to the buffer tank 1003. As the first circulation pump, a volumetric pump having a quantitative liquid conveying capacity is desirable. Specifically, a tube pump, a gear pump, a diaphragm pump, and a syringe pump are exemplified. However, for example, a universal constant flow valve or a universal pressure relief valve may be arranged at the outlet of the pump to ensure a predetermined flow rate. When the liquid ejection head 3 is driven, the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 are operated so that the ink flows through the common supply passage 211 and the common recovery passage 212 at a predetermined flow rate. Because the ink flows in this manner, the temperature of the liquid ejection head 3 is maintained at the optimum temperature during the printing operation. The predetermined flow rate at the time of driving the liquid ejection head 3 is desirably set to be equal to or higher than the flow rate at which the temperature difference between the printing element plates 10 inside the liquid ejection head 3 does not affect the printing quality. First, when an excessively high flow rate is set, the negative pressure difference between the printing element plates 10 may increase due to the influence of pressure loss of the internal channels of the liquid ejection unit 300, thus causing generation of image density unevenness. Therefore, it is desirable to set the flow rate in consideration of the temperature difference and the negative pressure difference between the printing element plates 10.

The negative pressure control unit 230 is disposed in a path between the second circulation pump 1004 and the liquid injection unit 300. The negative pressure control unit 230 is operated so as to maintain the pressure at the downstream side of the negative pressure control unit 230 (i.e., the pressure in the vicinity of the liquid ejection unit 300) at a predetermined pressure even when the ink flow rate in the circulation system varies due to the difference in the ink ejection amount per unit area. As the two negative pressure control mechanisms constituting the negative pressure control unit 230, any mechanism may be used as long as the pressure at the downstream side of the negative pressure control unit 230 can be controlled to be below a predetermined range with reference to a required set pressure. By way of example, a mechanism such as a so-called "pressure reducing regulator" may be employed. In the circulation passage of this application example, the upstream side of the negative pressure control unit 230 is pressurized by the second circulation pump 1004 via the liquid supply unit 220. With this configuration, since the influence of the water head pressure of the buffer tank 1003 with respect to the liquid ejection head 3 can be suppressed, the degree of freedom in the arrangement of the buffer tank 1003 of the printing apparatus 1000 can be widened.

As the second circulation pump 1004, a turbo pump or a displacement pump may be used as long as the pressure above the predetermined head pressure can be within the ink circulation flow rate range used when driving the liquid ejection head 3. In particular, a diaphragm pump may be used. Further, for example, instead of the second circulation pump 1004, a water head tank arranged to have a certain water head difference with respect to the negative pressure control unit 230 may also be used. As shown in fig. 27, the negative pressure control unit 230 includes two negative pressure adjusting mechanisms having different control pressures, respectively. In the two negative pressure adjustment mechanisms, a relatively high pressure side (indicated by "H" in fig. 27) and a relatively low pressure side (indicated by "L" in fig. 27) are connected to the common supply passage 211 and the common recovery passage 212 inside the liquid ejection unit 300, respectively, via the liquid supply unit 220. The liquid ejection unit 300 is provided with a common supply channel 211, a common recovery channel 212, and a single channel 215 (a single supply channel 213 and a single recovery channel 214) that communicate with the printing element board. The negative pressure control mechanism H is connected to the common supply passage 211, the negative pressure control mechanism L is connected to the common recovery passage 212, and a pressure difference is formed between the two

common passages

211 and 212. Then, since the single channel 215 communicates with the common supply channel 211 and the common recovery channel 212, a flow (a flow indicated by an arrow direction in fig. 27) is generated in which a part of the liquid flows from the common supply channel 211 to the common recovery channel 212 via a channel formed inside the printing element plate 10.

In this way, the liquid ejection unit 300 has a flow in which a part of the liquid flows through the printing element board 10 while flowing through the common supply channel 211 and the common recovery channel 212. Therefore, the heat generated by the printing element board 10 can be discharged to the outside of the printing element board 10 by the ink flowing through the common supply channel 211 and the common recovery channel 212. With this configuration, the flow of ink can be generated even in the pressure chambers or the ejection ports that do not eject liquid when the liquid ejection head 3 prints an image. Therefore, the ink can be suppressed from thickening, so that the viscosity of the ink thickened inside the ejection opening is reduced. Further, thickened ink or foreign matter in the ink can be discharged toward the common recovery passage 212. Therefore, the liquid ejection head 3 of this application example is capable of printing high-quality images at high speed.

(description of the second cycle type)

Fig. 28 is a schematic diagram showing a second circulation pattern which is different from the first circulation pattern in a circulation path suitable for an application-example printing apparatus. The main differences from the first cycle pattern are: both negative pressure control mechanisms constituting the negative pressure control unit 230 control the pressure at the upstream side of the negative pressure control unit 230 within a predetermined range with reference to an ideal set pressure. In addition, another difference from the first cycle pattern is: the second circulation pump 1004 serves as a negative pressure source for reducing the pressure at the downstream side of the negative pressure control unit 230. Furthermore, another difference is: a first circulation pump (high pressure side) 1001 and a first circulation pump (low pressure side) 1002 are arranged on the upstream side of the liquid ejection head 3, and the negative pressure control unit 230 is arranged at the downstream side of the liquid ejection head 3.

In the second circulation pattern, the ink inside the main tank 1006 is supplied to the buffer tank 1003 by the replenishment pump 1005. Then, the ink is divided into two channels, and circulates in the two channels at the high pressure side and the low pressure side by the action of the negative pressure control unit 230 provided in the liquid ejection head 3. The ink divided into two channels at the high pressure side and the low pressure side is supplied to the liquid ejection head 3 via the liquid connection portion 111 by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002. Then, the ink circulating inside the liquid ejection head by the action of the first circulation pump (high pressure side) 1001 and the first circulation pump (low pressure side) 1002 is discharged from the liquid ejection head 3 through the negative pressure control unit 230 and the liquid connection portion 111. The second circulation pump 1004 returns the discharged ink to the buffer tank 1003.

In the second cycle pattern, even when the flow rate varies due to a variation in the ejection amount per unit area, the negative pressure control unit 230 stabilizes the pressure variation at the upstream side (i.e., the liquid ejection unit 300 side) of the negative pressure control unit 230 within a predetermined range with respect to a predetermined pressure. In the circulation passage of the application example, the downstream side of the negative pressure control unit 230 is pressurized by the second circulation pump 1004 via the liquid supply unit 220. With this configuration, since the influence of the water head pressure of the buffer tank 1003 with respect to the liquid ejection head 3 can be suppressed, the arrangement of the buffer tank 1003 in the printing apparatus 1000 can have various options. Instead of the second circulation pump 1004, for example, a head tank arranged to have a predetermined head difference with respect to the negative pressure control unit 230 may also be used. Similar to the first cycle pattern, the negative pressure control unit 230 includes two negative pressure control mechanisms in the second cycle pattern, the two negative pressure control mechanisms having different control pressures, respectively. In the two negative pressure adjusting mechanisms, a high pressure side (denoted by "H" in fig. 28) and a low pressure side (denoted by "L" in fig. 28) are connected to the common supply passage 211 and the common recovery passage 212 inside the liquid ejection unit 300, respectively, via the liquid supply unit 220. When the pressure of the common supply channel 211 is set higher than the pressure of the common recovery channel 212 by the two negative pressure adjustment mechanisms, a liquid flow from the common supply channel 211 to the common recovery channel 212 via the single-use channel 215 and the channels formed inside the printing element board 10 is formed.

In this second circulation pattern, the same liquid flow as that of the first circulation pattern can be obtained inside the liquid ejection unit 300, but has two advantages different from those of the first circulation pattern. As a first advantage, in the second circulation pattern, since the negative pressure control unit 230 is arranged at the downstream side of the liquid ejection head 3, there is little fear that foreign substances or waste generated by the negative pressure control unit 230 flow into the liquid ejection head 3. As a second advantage, in the second circulation pattern, the maximum value of the flow rate required for the liquid to be supplied from the buffer tank 1003 to the liquid ejection head 3 is smaller than the maximum value of the flow rate in the first circulation pattern. The reason is as follows.

In the case of the printing standby state cycle, the sum of the flow rates of the common supply path 211 and the common recovery path 212 is set to the flow rate a. The value of the flow rate a is defined as a minimum flow rate required to adjust the temperature of the liquid ejection head 3 in the printing standby state so that the difference in the internal temperature of the liquid ejection unit 300 is within a required range. Further, the ejection flow rate obtained when ink is ejected from all the ejection openings of the liquid ejection unit 300 (full ejection state) is defined as a flow rate F (ejection amount per ejection opening × ejection frequency per unit time × number of ejection openings).

Fig. 29 is a schematic diagram showing a difference between the inflow amounts of ink flowing into the liquid ejection head 3 between the first circulation pattern and the second circulation pattern. Fig. 29(a) shows the standby state in the first cycle pattern, and fig. 29(b) shows the full injection state in the first cycle pattern. Fig. 29(c) to (f) show the second cycle pattern. Here, fig. 29(c) and (d) show the case where the flow rate F is lower than the flow rate a, and fig. 29(e) and (F) show the case where the flow rate F is higher than the flow rate a. In this way, the flow rate in the standby state and the flow rate in the full injection state are shown.

In the first circulation pattern ((a) and (b) in fig. 29), a first circulation pump 1001 and a first circulation pump 1002 each having a quantitative liquid conveying capacity are arranged at the downstream side of the liquid ejection head 3, and the total flow rate of the first circulation pump 1001 and the first circulation pump 1002 becomes the flow rate a. By virtue of the flow rate a, the temperature inside the liquid ejection unit 300 in the standby state can be managed. Then, in the full-ejection state of the liquid ejection head 3, the total flow rate of the first circulation pump 1001 and the first circulation pump 1002 becomes the flow rate a. However, by the negative pressure action generated by the ejection of the liquid ejection head 3, the flow rate F plus the flow rate a consumed by the full ejection is a total flow rate, and the maximum flow rate of the liquid supplied to the liquid ejection head 3 is obtained. Therefore, the maximum value of the supply amount supplied to the liquid ejection head 3 satisfies the relationship of { (flow rate a) + (flow rate F) }, because the flow rate F adds to the flow rate a (fig. 29 (b)).

On the other hand, in the case of the second circulation pattern (fig. 29(c) and 29(d)) in which the first circulation pump 1001 and the first circulation pump 1002 are arranged at the upstream side of the liquid ejection head 3, the supply amount to the liquid ejection head 3 required for the print standby state becomes the flow rate a, similarly to the first circulation pattern. Therefore, when the flow rate a is higher than the flow rate F (fig. 29(c) and 29(d)) in the second circulation pattern in which the first circulation pump 1001 and the first circulation pump 1002 are arranged at the upstream side of the liquid ejection head 3, the supply amount supplied to the liquid ejection head 3 sufficiently becomes the flow rate a even in the full ejection state. At this time, the discharge flow rate of the liquid ejection head 3 satisfies the relationship of { (flow rate a) - (flow rate F) } ((d) of fig. 29). However, when the flow rate F is higher than the flow rate a (fig. 29(e) and 29(F)), the flow rate becomes insufficient when the flow rate of the liquid supplied to the liquid ejection head 3 in the full ejection state becomes the flow rate a. Therefore, when the flow rate F is higher than the flow rate a, the supply amount to the liquid ejection head 3 needs to be set to the flow rate F. At this time, since the flow rate F is consumed by the liquid ejection head 3 in the full ejection state, the liquid flow rate discharged from the liquid ejection head 3 becomes almost zero (fig. 29 (F)). Further, if the liquid is ejected when the flow rate F is higher than the flow rate a but the liquid is not ejected in the full ejection state, the liquid discharged from the liquid ejection head 3 is the liquid decreased by the amount consumed by the ejection flow rate F. Further, when the flow rate a and the flow rate F are equal, the flow rate a (or the flow rate F) is supplied to the liquid ejection head 3, and the flow rate F is consumed by the liquid ejection head 3. Therefore, the flow rate discharged from the liquid ejection head 3 becomes almost zero.

In this way, in the case of the second circulation pattern, the total value of the set flow rates, that is, the maximum value required for the supply flow rates, for the first circulation pump 1001 and the first circulation pump 1002 becomes the large value of the flow rate a and the flow rate F. Therefore, as long as liquid ejection units 300 having the same configuration are used, the maximum value of the supply amount required for the second circulation pattern (flow rate a or flow rate F) becomes smaller than the maximum value of the supply flow rate required for the first circulation pattern { (flow rate a) + (flow rate F) }.

Thus, in the case of the second circulation pattern, the degree of freedom of the available circulation pump is increased. For example, a circulation pump having a simple configuration and low cost can be used, or the load of a cooler (not shown) provided in the main body side path can be reduced. Therefore, there is an advantage in that the cost of the printing apparatus can be reduced. This advantage is particularly prominent in line heads having a relatively large value of flow rate a or flow rate F. Therefore, a line head having a long longitudinal length is advantageous in the line head.

On the other hand, the first circulation pattern is more advantageous than the second circulation pattern. That is, in the second circulation pattern, since the liquid flow rate flowing through the liquid ejection unit 300 becomes the largest in the print standby state, a higher negative pressure is applied to the ejection port as the ejection amount per unit image area becomes smaller (hereinafter, also referred to as a low duty image). Therefore, when the channel width is narrow and the negative pressure is high, the high negative pressure is applied to the ejection port in a low duty ratio image where unevenness is liable to occur. Therefore, there is a fear that the print quality is degraded as the number of so-called satellite droplets ejected together with the ink main droplets increases.

On the other hand, in the case of the first cycle pattern, since a high negative pressure is applied to the ejection openings when an image having a large ejection amount per unit area (hereinafter also referred to as a high duty ratio image) is formed, there is an advantage in that even if many satellite droplets are generated, the influence of the satellite droplets on the image is small. The two circulation patterns can be desirably selected in consideration of specifications of the liquid ejection head and the printing apparatus main body (ejection flow rate F, minimum circulation flow rate a, and channel resistance inside the print head).

(description of the third cycle pattern)

Fig. 48 is a schematic diagram showing a third circulation pattern, which is one of the circulation paths used in the printing apparatus of this embodiment. The description of the same functions and configurations as the first and second circulating paths will be omitted, and only the differences will be described.

In this circulation path, liquid is supplied into the liquid ejection head 3 from three positions including two positions at the center of the liquid ejection head 3 and one end side of the liquid ejection head 3. The liquid flowing from the common supply channel 211 to each pressure chamber 23 is recovered by the common recovery channel 212, and the liquid is recovered to the outside from the recovery port at the other end portion of the liquid ejection head 3. The single channel 215 communicates with the common supply channel 211 and the common recovery channel 212, and the printing element board 10 and the pressure chamber 23 arranged inside the printing element board 10 are provided in the path of the single channel 215. Therefore, a part of the liquid flowing from the first circulation pump 1002 flows from the common supply passage 211 to the common recovery passage 212 while passing through the pressure chambers 23 of the printing element plate 10 (see the arrow of fig. 48). This is because a pressure difference is generated between the pressure adjusting mechanism H connected to the common supply passage 211 and the pressure adjusting mechanism L connected to the common recovery passage 212, and the first circulation pump 1002 is connected only to the common recovery passage 212.

In this way, in the liquid ejection unit 300, a liquid flow through the common recovery channel 212 and a liquid flow flowing from the common supply channel 211 to the common recovery channel 212 while passing through the pressure chamber 23 inside each printing element board 10 are generated. Therefore, the heat generated by each printing element plate 10 can be discharged to the outside of the printing element plate 10 by the flow flowing from the common supply channel 211 to the common recovery channel 212 while suppressing the pressure loss. Further, according to the circulation path, the number of pumps as the liquid conveying unit can be reduced as compared with the first and second circulation paths.

(description of liquid ejecting head construction)

The configuration of the liquid ejection head 3 according to the first application example will be described. Fig. 30A and 30B are perspective views showing the liquid ejection head 3 according to this application example. The liquid ejection head 3 is a line-type liquid ejection head in which fifteen printing element plates 10 capable of ejecting four color inks of cyan C, magenta M, yellow Y, and black K are arranged in series (in-line arrangement). As shown in fig. 30A, the liquid ejection head 3 includes: a printing element board 310; a signal input terminal 91 and a power supply terminal 92. The

terminals

91 and 92 are electrically connected to the printing element board 310 through the flexible circuit board 40 and the electric wiring board 90. The signal input terminal 91 and the power supply terminal 92 are electrically connected to the control unit of the printing apparatus 1000 so that an ejection drive signal and power necessary for ejection are supplied to the printing element board 310. When the wirings are integrated by the circuits inside the electric wiring board 90, the number of the signal input terminals 91 and the power supply terminals 92 can be reduced compared to the number of the printing element boards 310. Therefore, the number of electrical connection parts to be separated is reduced when assembling the liquid ejection head 3 to the printing apparatus 1000 or replacing the liquid ejection head. As shown in fig. 30B, liquid connection portions 111 provided at both ends of the liquid ejection head 3 are connected to a liquid supply system of the printing apparatus 1000. Thus, inks of four colors including cyan C, magenta M, yellow Y, and black K are supplied from the supply system of the printing apparatus 1000 to the liquid ejection head 3, and the inks passing through the liquid ejection head 3 are recovered by the supply system of the printing apparatus 1000. In this way, inks of different colors can be circulated through the path of the printing apparatus 1000 and the path of the liquid ejection head 3.

Fig. 31 is an exploded perspective view showing a constituent member or unit of the liquid ejection head 3. The liquid ejection unit 300, the liquid supply unit 220, and the electric wiring board 90 are mounted in the casing 380. The liquid connection portion 111 (see fig. 28) is provided in the liquid supply unit 220. Also, in order to remove foreign substances in the supplied ink, filters 221 (see fig. 27 and 28) for the inks of different colors are provided inside the liquid supply unit 220 while the filters 221 communicate with the openings of the liquid connecting portions 111. The two liquid supply units 220 are provided with filters 221 corresponding to two color inks, respectively. In the first circulation pattern as shown in fig. 27, the liquid passing through the filter 221 is supplied to the negative pressure control unit 230 disposed on the liquid supply unit 220 corresponding to each color ink. The negative pressure control unit 230 is a unit that includes negative pressure control valves corresponding to different color inks. By virtue of the function of the spring member or the valve provided therein, a variation in pressure loss inside the supply system of the printing apparatus 1000 (the supply system located at the upstream side of the liquid ejection head 3) due to a variation in the liquid flow rate is greatly reduced. Therefore, the negative pressure control unit 230 can stabilize the negative pressure variation at the downstream side of the negative pressure control unit (the liquid ejection unit 300 side) within a predetermined range. As shown in fig. 27, two negative pressure control valves corresponding to each color ink are provided inside the negative pressure control unit 230. The two negative pressure control valves are set to different control pressures, respectively. Here, the high pressure side of the two negative pressure control valves communicates with the common supply passage 211 (see fig. 27) inside the liquid ejection unit 300 through the liquid supply unit 220, and the low pressure side of the two negative pressure control valves communicates with the common recovery passage 212 (see fig. 27) through the liquid supply unit 220.

The casing 380 includes the liquid ejection unit support portion 381 and the electrical wiring board support portion 82, and ensures the rigidity of the liquid ejection head 3 while supporting the liquid ejection unit 300 and the electrical wiring board 90. The electric wiring board support 82 is for supporting the electric wiring board 90, and is fixed to the liquid ejection unit support 381 by screws. The liquid ejection unit support 381 is used to correct warpage or deformation of the liquid ejection unit 300 to ensure the relative positional accuracy between the printing element boards 310. Thus, streaking and unevenness of an image printed on a medium are suppressed. Therefore, it is desirable that the liquid ejecting unit supporting portion 381 have sufficient rigidity. As the material, a metal such as SUS or aluminum or a ceramic such as alumina is desirable. The liquid ejecting unit support portion 381 is provided with

openings

83 and 84, and rubber joints 100 are inserted into the

openings

83 and 84. The liquid supplied from the liquid supply unit 220 is introduced to the third passage member 370 constituting the liquid ejection unit 300 through the rubber joint 100.

The liquid ejection unit 300 includes a plurality of ejection modules 200 and a channel member 210, and the cover member 130 is mounted to a face of the liquid ejection unit 300 near a printing medium. Here, as shown in fig. 31, the cover member 130 is a member having a picture frame-like surface and provided with an elongated opening 131, and the printing element plate 310 and the sealing member 110 (see fig. 35A described later) included in the ejection module 200 are exposed from the opening 131. The frame of the opening 131 serves as a contact surface of a cover member that covers the liquid ejection head 3 in the print standby state. Therefore, it is desirable to form a closed space in the capping state by applying an adhesive, a sealing material, and a filling material along the periphery of the opening 131 to fill the uneven portion or the gap on the ejection port face of the liquid ejection unit 300.

Next, the configuration of the passage member 210 included in the liquid ejection unit 300 will be described. As shown in fig. 31, the channel member 210 is obtained by laminating a first channel member 50, a second channel member 60, and a third channel member 370, and the channel member 210 distributes the liquid supplied from the liquid supply unit 220 to the ejection module 200. Further, the channel part 210 is a channel part that returns the liquid recirculated from the spray module 200 to the liquid supply unit 220. The channel member 210 is fixed to the liquid ejection unit support portion 381 by screws, and thus warpage or deformation of the channel member 210 is suppressed.

Fig. 32(a) to (f) are diagrams showing the front and back surfaces of the first to third channel members. Fig. 32(a) shows a face of the first passage member 50 to which the ejection module 200 is to be mounted, and fig. 32(f) shows a face of the third passage member 370 that contacts the liquid ejection unit support portion 381. The first passage member 50 and the second passage member 60 are engaged with each other such that portions corresponding to the contact surfaces of the

passage members

50 and 60 shown in fig. 32(b) and (c) face each other. The second passage member 60 and the third passage member 370 are engaged with each other such that portions corresponding to the contact surfaces of the

passage members

60 and 370 shown in (d) and (e) in fig. 32 face each other. When the second channel member 60 and the third channel member 370 are engaged with each other, eight common channels (211a, 211b, 211c, 211d, 212a, 212b, 212c, 212d) extending in the longitudinal direction of the channel members are formed by the

common channel grooves

362 and 371 of the second and third channel members. Therefore, a set of the common supply path 211 and the common recovery path 212 is formed inside the path member 210 to correspond to each color ink. The ink is supplied from the common supply channel 211 to the liquid ejection head 3, and the ink supplied to the liquid ejection head 3 is recovered by the common recovery channel 212. The communication port 72 (see fig. 32(f)) of the third passage member 370 communicates with the corresponding hole of the rubber joint 100, and is connected in fluid communication to the liquid supply unit 220 (see fig. 31). The bottom surface of the common channel groove 62 of the second channel member 60 is provided with a plurality of communication ports 361 (a communication port 361-1 communicating with the common supply channel 211 and a communication port 361-2 communicating with the common recovery channel 212). The communication port 361 communicates with one end portion of the corresponding single-passage groove 352 of the first passage member 50. The other end portion of the single-channel groove 352 of the first channel member 50 is provided with a communication port 351, and is connected to the ejection module 200 in fluid communication through the communication port 351. With the single passage groove 352, the passages can be densely arranged at the center side of the passage member.

It is desirable that the first to third channel members be formed of a material having liquid corrosion resistance and having a low linear expansion coefficient. As the material, for example, a composite material (resin) obtained by adding an inorganic filler such as fibers or fine silicon particles to a base material such as alumina, LCP (liquid crystal polymer), PPS (polyphenylene sulfide), PSF (polysulfone), or modified PPE (polyphenylene ether) may be suitably used. As a method of forming the channel member 210, three channel members may be laminated and adhered to each other. When a resin composite material is selected as the material, a joining method using welding may be applied.

Fig. 33 is a partially enlarged perspective view showing when viewed from the face where the injection module 200 is mounted on the first passage member 50, shows a portion α of fig. 32(a), and shows a passage inside the passage member 210 formed by joining the first passage member to the third passage member to each other, the common supply passage 211 and the common recovery passage 212 are formed such that the common supply passage 211 and the common recovery passage 212 are alternately arranged from the passages at both ends, and here, the connection relationship between the passages inside the passage member 210 will be described.

A common supply channel 211(211a, 211b, 211c, 211d) and a common recovery channel 212(212a, 212b, 212c, 212d) extending in the longitudinal direction of the liquid ejection head 3 are provided in the channel member 210 for ink of each color. The single-use supply channels 213(213a, 213b, 213c, 213d) formed by the single-use channel grooves 352 are connected to the common supply channel 211 for the different color inks through the communication ports 361. Further, the single recovery passages 214(214a, 214b, 214c, 214d) formed by the single passage grooves 352 are connected to the common recovery passage 212 for the different color inks through the communication port 361. With this channel configuration, ink can be collectively supplied from the common supply channel 211 to the printing element board 310 located at the central portion of the channel member through the single-use supply channel 213. Further, the ink can be recovered from the printing element board 310 to the common recovery channel 212 through the single recovery channel 214.

FIG. 34 is a cross-sectional view taken along line XXXIV-XXXIV of FIG. 33. The individual recovery passages (214a, 214c) communicate with the ejection module 200 through the communication port 351. Only the single recovery channel (214a, 214c) is shown in fig. 34, but in a different cross-sectional view, the single supply channel 213 and the spray module 200 shown in fig. 33 communicate with each other. The support member 330 and the printing element board 310 included in each ejection module 200 are provided with channels for supplying ink from the first channel member 50 to the printing elements 315 provided in the printing element board 310. Further, the supporting member 330 and the printing element plate 310 are provided with a passage for recovering (recycling) a part or all of the liquid supplied to the printing elements 315 to the first passage member 50.

Here, the common supply channel 211 for each color ink is connected to the negative pressure control unit 230 (high pressure side) for the corresponding color ink through the liquid supply unit 220, and the common recovery channel 212 is connected to the negative pressure control unit 230 (low pressure side) through the liquid supply unit 220. A pressure difference (pressure difference) is generated between the common supply passage 211 and the common recovery passage 212 by the negative pressure control unit 230. Therefore, as shown in fig. 33 and 34, the liquid flow of each color ink is generated in the order of the common supply channel 211, the individual supply channel 213, the printing element plate 310, the individual recovery channel 214, and the common recovery channel 212 inside the liquid ejection head of this application example in which the channels are connected to each other.

(description of the injection Module)

Fig. 35A is a perspective view showing one jetting module 200, and fig. 35B is an exploded view thereof. As a method of manufacturing the ejection module 200, first, the printing element board 310 and the flexible circuit board 40 are bonded to the support member 330, the support member 330 being provided with the liquid communication port 31. Then, the terminals 316 on the printing element board 310 and the terminals 341 on the flexible circuit board 40 are electrically connected to each other by wire bonding, and the wire bonding portions (electrical connection portions) are sealed by the sealing member 110. The terminals 342 of the flexible circuit board 40 on the side opposite to the printing element board 310 side are electrically connected to the connection terminals 93 of the electric wiring board 90 (see fig. 6). Since the supporting member 330 serves as a support for supporting the printing element plate 310 and the channel member that fluidically communicates the printing element plate 310 and the channel member 210 with each other, it is desirable that the supporting member 330 has high flatness and sufficiently high reliability in the case of bonding to the printing element plate. As the material, for example, alumina or resin is desirable.

(description of printing element plate Structure)

Fig. 36A is a plan view showing a face where the ejection port 313 is provided in the printing element plate 310, fig. 36B is an enlarged view of a portion a of fig. 36A, and fig. 36C is a plan view showing a back face of fig. 36A. Here, the configuration of the printing element board 310 of the application example will be described. As shown in fig. 36A, the ejection port forming member 312 of the printing element plate 310 is provided with four ejection port arrays corresponding to different color inks. Further, the extending direction of the ejection opening array of the ejection openings 313 will be referred to as "ejection opening array direction". As shown in fig. 36B, a printing element 315 as an ejection energy generating element for ejecting liquid by thermal energy is arranged at a position corresponding to each ejection port 313. A pressure chamber 323 in which the printing element 315 is disposed is defined by a partition wall 322. The printing element 315 is electrically connected to the terminal 316 through an electrical lead (not shown) provided in the printing element board 310. Then, the printing element 315 causes the liquid to boil by heating in accordance with a pulse signal input from a control circuit of the printing apparatus 1000 via the electric wiring board 90 (see fig. 31) and the flexible circuit board 40 (see fig. 35B). The liquid is ejected from the ejection port 313 by the foaming force generated by boiling. As shown in fig. 36B, the liquid supply path 318 extends on one side along each ejection port array, and the liquid recovery path 319 extends on the other side along the ejection port array. The liquid supply path 318 and the liquid recovery path 319 are channels that extend in the ejection port array direction provided in the printing element plate 310 and communicate with the ejection ports 313 through supply ports 317a and recovery ports 317 b.

As shown in fig. 36C, a plate-shaped cover plate (cover member) 20 is laminated on the back surface of the face of the printing element plate 310 where the ejection ports 313 are provided, and the cover plate 20 is provided with a plurality of openings 20A communicating with the liquid supply path 318 and the liquid recovery path 319. In this application example, the cover plate 20 is provided with three openings 20A for each liquid supply path 318 and two openings 20A for each liquid recovery path 319. As shown in fig. 36B, the opening 20A of the cover plate 20 communicates with a communication port 351 shown in (a) in fig. 32. It is desirable that the cover plate 20 have sufficient liquid corrosion resistance. From the viewpoint of preventing color mixing, the opening shape and the opening position of the opening 20A need to have high accuracy. Therefore, it is desirable to form the opening 20A by photolithography using a photosensitive resin material or a silicon plate as a material of the cover plate 20. In this manner, the cover plate 20 changes the spacing of the channels through the openings 20A. Here, it is desirable to form the cover plate 20 by a thin film-like member in consideration of pressure loss.

Fig. 37 is a cross-sectional perspective view showing the print element plate 310 and the cover plate 20 when taken along line XXXVII-XXXVII of fig. 36A. Here, the flow of liquid inside the printing element plate 310 will be described. The cover plate 20 serves as a cover that constitutes a part of the walls of the liquid supply path 318 and the liquid recovery path 319 formed in the substrate 311 of the printing element board 310. The printing element plate 310 is formed by laminating a substrate 311 formed of silicon and an ejection port forming member 312 formed of a photosensitive resin, and a cover plate 20 is bonded to the back surface of the substrate 311. One surface of the substrate 311 is provided with a printing element 315 (see fig. 36B), and the back surface is provided with grooves that form a liquid supply path 318 and a liquid recovery path 319 extending along the ejection port array. The liquid supply path 318 and the liquid recovery path 319 formed by the base plate 311 and the cover plate 20 are connected to the common supply passage 211 and the common recovery passage 212 inside each passage member 210, respectively, and a pressure difference is generated between the liquid supply path 318 and the liquid recovery path 319. When liquid is ejected from the ejection ports 313 to print an image, at the ejection ports where the liquid is not ejected, the liquid inside the liquid supply path 318 provided in the substrate 311 flows toward the liquid recovery path 319 through the supply port 317a, the pressure chamber 323, and the recovery port 317b by the pressure difference (see arrow C of fig. 37). By virtue of the flow, foreign substances, bubbles, and thick ink generated by evaporation from the ejection port 313 in the ejection port 313 or the pressure chamber 323, which are not related to the printing operation, can be recovered by the liquid recovery path 319. Further, thickening of the ink in the ejection ports 313 or the pressure chambers 323 can be suppressed. The liquid recovered into the liquid recovery path 319 is recovered through the opening 20A of the cover plate 20 and the liquid communication port 31 (see fig. 35B) of the support member 330 in the order of the communication port 351 inside the channel member 210, the single-use recovery channel 214, and the common recovery channel 212. Then, the liquid is recovered by a recovery path of the printing apparatus 1000. That is, the liquid supplied from the printing apparatus main body to the liquid ejection head 3 flows in the following order so as to be supplied and recovered.

First, the liquid flows into the liquid ejection head 3 from the liquid connection portion 111 of the liquid supply unit 220. Then, the liquid is supplied sequentially through the rubber joint 100, the communication port 72 and the common channel groove 371 provided in the third channel member, the common channel groove 362 and the communication port 361 provided in the second channel member, and the single channel groove 352 and the communication port 351 provided in the first channel member. Then, the liquid is supplied to the pressure chamber 323 while successively passing through the liquid communication port 31 provided in the support member 330, the opening 20A provided in the cover plate 20, and the liquid supply path 318 and the supply port 317a provided in the base plate 311. Among the liquids supplied to the pressure chambers 323, the liquids that are not ejected from the ejection openings 313 successively flow through the recovery openings 317b and the liquid recovery paths 319 provided in the substrate 311, the openings 20A provided in the cover plate 20, and the liquid communication openings 31 provided in the support member 330. Then, the liquid flows successively through the communication port 351 and the single-use channel groove 352 provided in the first channel member, the communication port 361 and the common channel groove 362 provided in the second channel member, the common channel groove 371 and the communication port 72 provided in the third channel member 370, and the hole of the rubber joint 100. Then, the liquid flows from the liquid connection portion 111 provided in the liquid supply unit 220 to the outside of the liquid ejection head 3.

In the first circulation pattern shown in fig. 27, the liquid flowing from the liquid connection portion 111 is supplied to the hole of the rubber joint 100 by the negative pressure control unit 230. Further, in the second circulation pattern shown in fig. 28, the liquid recovered from the pressure chamber 323 flows through the hole of the rubber joint 100, and is made to flow from the liquid recovery portion 111 to the outside of the liquid ejection head by the negative pressure control unit 230. All the liquid flowing from one end portion of the common supply passage 211 of the liquid ejection unit 300 is not supplied to the pressure chamber 323 through the single-use supply passage 213 a. That is, the liquid flowing from one end of the common supply channel 211 may flow from the other end of the common supply channel 211 to the liquid supply unit 220 while not flowing into the single-use supply channel 213 a. In this way, since the path is provided so that the liquid flows through while not flowing through the printing element plate 310, the occurrence of the reverse flow of the circulation flow of the liquid can be suppressed even in the printing element plate 310 including a small channel of large flow resistance as in this application example. In this way, since thickening of the liquid in the vicinity of the ejection ports and the pressure chambers 23 can be suppressed in the liquid ejection head 3 of this application example, it is possible to suppress liquid slipping or inability to eject. As a result, a high-quality image can be printed.

(description of positional relationship between printing element boards)

Fig. 38 is a partially enlarged top view showing adjacent portions of the printing element plates in two adjacent ejection modules. In this application example, a substantially parallelogram-shaped printing element plate is used. The ejection port arrays (14a to 14d) having the ejection ports 313 provided in each printing element plate 310 are arranged to be inclined at a predetermined angle with respect to the longitudinal direction of the liquid ejection head 3. Then, the ejection opening arrays at the adjacent portions between the printing element plates 310 are formed such that at least one ejection opening overlaps in the printing medium conveyance direction. In fig. 38, two ejection ports on the line D overlap each other. With this arrangement, even if the position of the printing element plate 310 is slightly deviated from the predetermined position, the black stripe of the printed image or omission of the printed image can be made inconspicuous by the drive control of the overlapping ejection openings. Even if the printing element plates 310 are arranged in a straight line (linear) shape instead of a zigzag shape, black streaks or omissions at the connection portions between the printing element plates 10 can be solved while suppressing an increase in the length of the liquid ejection head 3 in the printing medium conveyance direction by the configuration shown in fig. 38. Further, in this application example, the principal plane of the printing element board is a parallelogram, but the present invention is not limited to this. For example, even when a printing element plate of a rectangular shape, a trapezoidal shape, and other shapes is used, the configuration of the present invention can be desirably used.

(description of the liquid ejecting head configuration modification)

A modification of the liquid ejection head configuration shown in fig. 47 and fig. 49 to 51 will be described. Description of the same configuration and function as in the above-described example will be omitted, and only the differences will be mainly described. In a modification, as illustrated in fig. 47, 49A, and 49B, the liquid connection portions 111 between the liquid ejection head 3 and the outside are collectively arranged on one end portion side of the liquid ejection head in the longitudinal direction. The negative pressure control unit 230 is centrally arranged at the other end side of the liquid ejection head 3 (fig. 50). The liquid supply unit 220 belonging to the liquid ejection head 3 is configured as an elongated unit corresponding to the length of the liquid ejection head 3, and includes channels and filters 221 corresponding to the supplied four color liquids, respectively. As shown in fig. 50, the positions of the openings 83 to 86 provided on the liquid ejecting unit supporting part 81 are also located at positions different from the positions of the liquid ejecting head 3.

Fig. 51 shows a laminated state of the

channel members

50, 60, and 70. The printing element boards 10 are arranged in line on the upper surface of the passage member 50, the passage member 50 being the uppermost layer among the

passage members

50, 60, and 70. As channels communicating with the opening 20A (fig. 36C) of the cover member 20 positioned at the back side of each printing element plate 10, two single-use supply channels 213 and one single-use recovery channel 214 are provided for each color of liquid. Therefore, as the openings 20A formed on the cover plate 20 provided at the back surface of the printing element plate 10, two supply ports 20A and one recovery port 20A are provided for the liquid of each color. As shown in fig. 51, the common supply channels 211 and the common recovery channels 212 extending in the longitudinal direction of the liquid ejection head 3 are alternately arranged.

(second application example)

Hereinafter, the configurations of the ink jet printing apparatus 2000 and the liquid ejection head 2003 according to the second application example of the present invention will be described with reference to the drawings. In the following description, only the differences from the first application example will be described, and the description of the same components as in the first application example will be omitted.

(description of ink jet printing apparatus)

Fig. 46 is a diagram showing an inkjet printing apparatus 2000 for ejecting liquid according to this application example. The printing apparatus 2000 of this application example is different from the first application example in that: a full-color image is printed on a printing medium by a configuration in which four single-color liquid ejection heads 2003, corresponding to inks of cyan C, magenta M, yellow Y, and black K, respectively, are arranged side by side. In the first application example, the number of ejection opening arrays available for one color is one. However, the number of ejection opening arrays usable for one color in the present application example is twenty. Therefore, when the print data is appropriately distributed to the plurality of ejection port arrays to print an image, the image can be printed at a higher speed. Further, even when there are ejection ports that do not eject liquid, it is possible to complementarily eject liquid from ejection ports in other arrays located at positions corresponding to the non-ejection ports along the printing medium conveyance direction. Reliability is improved, and thus a commercial image can be appropriately printed. Similar to the first application example, the supply system of the printing apparatus 2000, the buffer tank 1003 (see fig. 27 and 28), and the main tank 1006 (see fig. 27 and 28) are connected in fluid communication to the liquid ejection head 2003. Further, an electronic control unit is electrically connected to the liquid ejection head 2003, and the electronic control unit transmits power and an ejection control signal to the liquid ejection head 2003.

(description of circulation path)

Similarly to the first application example, the first and second circulation patterns shown in fig. 27 or 28 can be used as the liquid circulation pattern between the printing apparatus 2000 and the liquid ejection head 2003.

(structural description of liquid ejecting head)

Fig. 39A and 39B are perspective views showing a liquid ejection head 2003 according to this application example. Here, the configuration of the liquid ejection head 2003 according to this application example will be described. The liquid ejection head 2003 is a line-type inkjet head which includes sixteen printing element plates 2010 arranged linearly along the longitudinal direction of the liquid ejection head 2003 and is capable of printing by one liquid. The liquid ejection head 2003 includes a liquid connection portion 111, a signal input terminal 91, and a power supply terminal 92, similarly to the first application example. However, since the liquid ejection head 2003 of this application example includes more ejection port arrays than the first application example, the signal input terminal 91 and the power supply terminal 92 are arranged on both sides of the liquid ejection head 2003. This is because it is necessary to reduce a voltage drop or a signal transfer delay caused by a wiring portion provided in the printing element board 2010.

Fig. 40 is an oblique exploded view showing the liquid ejection head 2003 and components or units constituting the liquid ejection head 2003 according to the function thereof. The functions or the liquid flow order of the respective units and members inside the liquid ejection head are substantially similar to those of the first application example, but the functions of ensuring the rigidity of the liquid ejection head are different. In the first application example, the rigidity of the liquid ejection head is mainly ensured by the liquid ejection unit support portion 381, but in the liquid ejection head 2003 of the second application example, the rigidity of the liquid ejection head 2003 is ensured by the second channel member 2060 included in the liquid ejection unit 2300. The liquid ejection unit support portions 381 of this application example are connected to both ends of the second channel member 2060, and the liquid ejection unit 2300 is mechanically connected to the carriage of the printing apparatus 2000 so as to position the liquid ejection head 2003. The electric wiring board 90 and the liquid supply unit 2220 including the negative pressure control unit 2230 are connected to the liquid ejecting unit support 381. Each of the two liquid supply units 2220 includes a built-in filter (not shown).

The two negative pressure control units 2230 are set to control pressures at different (relatively high negative pressure and relatively low negative pressure). Further, as shown in fig. 39A, 39B, and 40, when the negative pressure control units 2230 at the high pressure side and the low pressure side are provided at both end portions of the liquid ejection head 2003, the liquid flows in the common supply channel and the common recovery channel extending in the longitudinal direction of the liquid ejection head 2003 face each other. In this configuration, heat exchange between the common supply passage and the common recovery passage is promoted, and thus the temperature difference inside the two common passages is reduced. Therefore, the temperature difference of the printing element boards 2010 disposed along the common path is reduced. As a result, there is an advantage in that printing unevenness is less likely to occur due to a temperature difference.

Next, the detailed configuration of the channel parts 2210 of the liquid ejecting unit 2300 will be described. As shown in FIG. 40, the channel parts 2210 are obtained by laminating the first channel part 2050 and the second channel part 2060, and the channel parts 2210 distribute the liquid supplied from the liquid supply unit 2220 to the spray module 2200. The passage part 2210 serves as a passage part for returning the liquid circulated from the spray module 2200 to the liquid supply unit 2220. The second channel member 2060 of the channel member 2210 is a channel member in which the common supply channel and the common recovery channel are formed and the rigidity of the liquid ejection head 2003 is improved. Therefore, it is desirable that the material of the second passage member 2060 have sufficient liquid corrosion resistance and high mechanical strength. Specifically, SUS stainless steel, titanium, or alumina can be used.

Fig. 41(a) is a diagram showing a face of the first passage member 2050 on which the injection module 2200 is to be mounted, and fig. 41(b) is a diagram showing a back face thereof and a face which is in contact with the second passage member 2060. Unlike the first application example, the first channel member 2050 of the present application example has a configuration in which a plurality of members corresponding to the jetting module 2200 are adjacently arranged. By adopting such a split structure, a plurality of modules can be arranged to correspond to the length of the liquid ejection head 2003. Therefore, such a structure can be suitably applied particularly to a relatively long liquid ejection head corresponding to a sheet of a size of, for example, B2 or more. As shown in fig. 41(a), the communication port 351 of the first passage member 2050 is in fluid communication with the ejection module 2200. As shown in fig. 41(b), the single communication port 353 of the first passage member 2050 is in fluid communication with the communication port 361 of the second passage member 2060. Fig. 41(c) shows the contact surface of the second channel member 2060 with respect to the first channel member 2050, fig. 41(d) shows a cross-sectional view of the central portion of the second channel member 2060 in the thickness direction, and fig. 41(e) shows a schematic view of the contact surface of the second channel member 2060 with respect to the liquid supply unit 2220. The communication ports and the channels of the second passage member 2060 function similarly to each color of the first application example. The common channel groove 371 of the second channel member 2060 is formed such that one side thereof is a common supply channel 2211 shown in fig. 42 and the other side thereof is a common recovery channel 2212. These

passages

2211 and 2212 are provided along the longitudinal direction of the liquid ejection head 2003, respectively, so that the liquid is supplied from one end portion thereof to the other end portion thereof. The difference between this application and the first application is that: the liquid flow direction in the common supply passage 2211 is opposite to the liquid flow direction in the common recovery passage 2212.

Fig. 42 is a perspective view showing a liquid connection relationship between the printing element board 2010 and the path member 2210. A pair of a common supply passage 2211 and a common recovery passage 2212 extending in the longitudinal direction of the liquid ejection head 2003 are provided inside the passage member 2210. The communication port 361 of the second passage member 2060 is connected to the single communication port 353 of the first passage member 2050 so that the two positions match each other. A liquid supply passage is thus formed which communicates from the common supply passage 2211 of the second passage member 2060 to the communication port 351 of the first passage member 2050 through the communication port 361. Similarly, a liquid supply path that communicates from the communication port 72 of the second passage member 2060 to the communication port 351 of the first passage member 2050 through the common recovery passage 2212 is also formed.

FIG. 43 is a cross-sectional view taken along line XLIII-XLIII of FIG. 42. The common supply passage 2211 is connected to the ejection module 2200 through the communication port 361, the single-use communication port 353, and the communication port 351. Although not shown in fig. 43, it is apparent that in a different cross-sectional view in fig. 42, the common recovery passage 2212 is connected to the jetting module 2200 by the same path. Similar to the first application example, the ejection module 2200 and the printing element board 2010 are each provided with a passage communicating with each ejection port, and therefore a part or all of the supply liquid can be circulated through the ejection ports where the ejection operation is not performed. Further, similar to the first application example, the common supply passage 2211 is connected to the negative pressure control unit 2230 (high pressure side) through the liquid supply unit 2220, and the common recovery passage 2212 is connected to the negative pressure control unit 2230 (low pressure side) through the liquid supply unit 2220. Thus, a flow is formed such that the liquid flows from the common supply passage 2211 to the common recovery passage 2212 through the pressure chambers of the printing element board 2010 due to the pressure difference.

(description of the injection Module)

Fig. 44A is a perspective view showing one jetting module 2200, and fig. 44B is an exploded view thereof. The difference from the first application case is that: the terminals 316 are respectively arranged at both sides in the ejection port array direction on the printing element board 2010 (long side portions of the printing element board 2010). Thus, two flexible circuit boards 40 electrically connected to the printing element board 2010 are arranged for each printing element board 2010. Since the number of ejection port arrays provided in the printing element board 2010 is twenty, the ejection port arrays are more than the eight ejection port arrays of the first application example. Here, since the maximum distance between the terminal 316 and the printing element is shortened, a voltage drop or a signal delay generated in the wiring portion inside the printing element board 2010 is reduced. Further, the liquid communication port 31 of the support member 2030 opens along the entire ejection port array provided in the printing element board 2010. The other configuration is similar to that of the first application example.

(description of printing element plate Structure)

Fig. 45A is a schematic diagram showing a face of the printing element board 2010 where the ejection ports 313 are arranged, and fig. 45C is a schematic diagram showing a back face of the face of fig. 45A. Fig. 45B is a schematic diagram showing a face of the printing element board 2010 when the cover plate 2020 provided on the back face of the printing element board 2010 in fig. 45C is removed. As shown in fig. 45B, a liquid supply path 318 and a liquid recovery path 319 are alternately provided along the ejection port array direction at the back surface of the printing element board 2010. The number of ejection opening arrays is larger than that of the first application example. However, the fundamental difference from the first application is that: the terminals 316 are arranged at both sides of the printing element board along the ejection port array direction as described above. The basic construction is similar to the first application in that: a pair of a liquid supply path 318 and a liquid recovery path 319 are provided in each ejection port array, and the cap plate 2020 is provided with an opening 20A communicating with the liquid communication port 31 of the support member 2030.

Furthermore, the above description of application examples does not limit the scope of the present invention. As an example, a thermal type in which bubbles are generated by a heating element to eject liquid has been described in the application examples. However, the present invention can also be applied to liquid ejection heads employing a piezoelectric type and other various liquid ejection types.

An ink jet printing apparatus (printing apparatus) in which liquid such as ink is circulated between a tank and a liquid ejection head has been described in the application examples, but other application examples may also be used. In other application examples, for example, a configuration may be adopted in which ink is not circulated, and two tanks are provided at the upstream side and the downstream side of the liquid ejection head so that ink flows from one tank to the other tank. In this way, the ink inside the pressure chamber can flow.

The example of using the so-called line head having a length corresponding to the width of the printing medium has been described in the application example, but the present invention can also be applied to a so-called serial liquid ejection head that prints an image on a printing medium while scanning the printing medium. As the string-type liquid ejection head, for example, the liquid ejection head may be equipped with a printing element plate that ejects black ink and a printing element plate that ejects color ink, but the present invention is not limited thereto. That is, a liquid ejection head that is shorter than the width of the printing medium, which includes a plurality of printing element plates arranged such that ejection ports overlap with each other in the ejection port array direction, may be provided, and the liquid ejection head may scan with respect to the printing medium.

(third application example)

The configurations of the ink jet printing apparatus 1000 and the liquid ejection head 3 according to the third application example of the present invention will be described. The liquid ejection port of the third application example is of a wide type in which an image is printed on a B2 print medium by one scan. Since the third application example is similar to the second application example in various respects, only differences from the second application example will be mainly described hereinafter, and description of the same configuration as the second application example will be omitted.

(description of ink jet printing apparatus)

Fig. 52 is a schematic diagram showing an inkjet printing apparatus according to this application example. The printing apparatus 1000 has a configuration in which an image is not directly printed on a printing medium by liquid ejected from the liquid ejection head 3. That is, the liquid is first ejected to an intermediate transfer member (intermediate transfer drum) 1007 to form an image thereon, and the image is transferred to the printing medium 2. In the printing apparatus 1000, the liquid ejection heads 3 respectively corresponding to the four color (C, M, Y, K) inks are arranged in a circular arc shape along the intermediate transfer drum 1007. Accordingly, full-color printing processing is performed on the intermediate transfer member, the printed image is appropriately dried on the intermediate transfer member, and the image is transferred to the printing medium 2 conveyed to the transfer portion 1008 by the sheet conveying roller 1009. The sheet conveying system of the second application example is mainly used for conveying the cut sheet in the horizontal direction. However, the sheet conveying system of the present application example can also be applied to a continuous sheet supplied from a main roller (not shown). In such a drum conveyance system, since it is easy to convey a sheet with a predetermined tension applied, conveyance jam hardly occurs even in a high-speed printing operation. Therefore, the reliability of the apparatus is improved, and therefore the apparatus is suitable for commercial printing purposes. Similarly to the first and second application examples, the supply system of the printing apparatus 1000, the buffer tank 1003, and the main tank 1006 are connected to each liquid ejection head 3 in fluid communication. Further, an electric control unit is electrically connected to each liquid ejection head 3, and the electric control unit transmits an ejection control signal and electric power to the liquid ejection heads 3.

(for the fourth cycle type description)

The first and second circulation paths shown in fig. 27 or 28 can also be applied to the liquid circulation paths between the liquid ejection head 3 and the tanks of the printing apparatus 1000, similar to the second application example, but the circulation path shown in fig. 53 is desirably employed. The main differences from the second circulation path of fig. 28 are: a bypass valve 1010 is additionally provided, which communicates with both passages of the first circulation pumps 1001 and 1002 and the second circulation pump 1004. The bypass valve 1010 has a function (first function) of reducing the pressure upstream of the bypass valve 1010 by opening the valve when the pressure exceeds a predetermined pressure. Further, the bypass valve 1010 has a function (second function) of opening and closing the valve at an arbitrary timing by a signal from a control substrate of the printing apparatus main body.

By the first function, it is possible to suppress the application of a large pressure or a small pressure to the downstream side of the first circulation pumps 1001 and 1002 or the upstream side of the second circulation pump 1004. For example, when the functions of the first circulation pumps 1001 and 1002 do not work properly, there may be a case where a large flow rate or a large pressure is applied to the liquid ejection head 3. Therefore, there is a fear that liquid may leak from the ejection ports of the liquid ejection head 3 or each joint inside the liquid ejection head 3 may be broken. However, when the bypass valve 1010 is added to the first circulation pumps 1001 and 1002 as in this application example, the bypass valve 1010 is opened in the case of a large pressure. Therefore, since the liquid path is opened to the upstream side of each circulation pump, the occurrence of the above-described failure can be suppressed.

Further, with the second function, when the circulation driving operation is stopped, all the bypass valves 1010 are quickly opened based on the control signal of the printing apparatus main body after the operations of the first circulation pumps 1001 and 1002 and the second circulation pump 1004 are stopped. Therefore, the high negative pressure (for example, several tens kPa) at the downstream portion of the liquid ejection head 3 (between the negative pressure control unit 230 and the second circulation pump 1004) can be released in a short time. When a displacement pump such as a diaphragm pump is used as the circulation pump, a check valve is generally provided in the pump. However, when the bypass valve 1010 is opened, the pressure at the downstream portion of the liquid jet head 3 can also be released from the downstream portion of the buffer tank 1003. Although the pressure at the downstream portion of the liquid ejection head 3 can be released only from the upstream side, a pressure loss exists in the upstream passage of the liquid ejection head and the passage inside the liquid ejection head. Therefore, since it takes time to take a certain time when the pressure is released, the pressure in the common passage inside the liquid ejection head 3 momentarily drops too much. Therefore, there is a fear that the meniscus in the ejection port may be broken. However, since the downstream pressure of the liquid ejection head is further released when the bypass valve 1010 at the downstream side of the liquid ejection head 3 is opened, the risk of the meniscus in the ejection port being broken is reduced.

(description of liquid injection head Structure)

The structure of the liquid ejection head 3 according to the third application example of the present invention will be described. Fig. 54A is a perspective view showing the liquid ejection head 3 according to this application example, and fig. 54B is an exploded perspective view thereof. The liquid ejection head 3 is a wide-format inkjet printhead which includes thirty-six printing element plates 10 arranged in a straight line (in-line type) along the longitudinal direction of the liquid ejection head 3, and prints an image with one color. Similarly to the second application example, the liquid ejection head 3 includes the shielding plate 132, and the shielding plate 132 protects the rectangular side face of the print head in addition to shielding the signal input terminal 91 and the power supply terminal 92.

Fig. 54B is an exploded perspective view showing the liquid ejection head 3. In fig. 54B, members or units (the shielding plate 132 is not shown) constituting the liquid ejection head 3 are divided and shown according to functions. The functions of these units and parts and the liquid circulation sequence inside the liquid ejection head 3 are similar to those of the second application example. The main differences from the second application example are: the divided electric wiring board 90 and the negative pressure control unit 230 are arranged at different positions, and the first passage member has different shapes. As in the present application example, for example, in the case of the liquid ejection head 3 having a length corresponding to a B2-size printing medium, the power consumed by the liquid ejection head 3 is large, and therefore eight electric wiring boards 90 are provided. Four electrical wiring boards 90 are mounted on each of both side surfaces of the elongated electrical wiring board support 82, and the elongated electrical wiring board support 82 is mounted to the liquid ejecting unit support 81.

Fig. 55A is a side view showing the liquid ejection head 3, the liquid ejection head 3 including a liquid ejection unit 300, a liquid supply unit 220, and a negative pressure control unit 230, fig. 55B is a schematic diagram showing the flow of liquid, and fig. 55C is a sectional view showing a line LVC-LVC taken along the line LVC of fig. 55A. A part of the configuration is simplified for easy understanding of the drawings.

The liquid connection part 111 and the filter 221 are disposed inside the liquid supply unit 220, and the negative pressure control unit 230 is integrally formed at the lower side of the liquid supply unit 220. Therefore, the distance between the negative pressure control unit 230 and the printing element board 10 in the height direction becomes shorter than that of the second application example. With this configuration, the number of passage connections inside the liquid supply unit 220 is reduced. As a result, the advantages are: the reliability of preventing the printing liquid from leaking is improved, and the number of parts or assembly steps is reduced.

Further, since the water head difference between the negative pressure control unit 230 and the ejection port formation surface of the liquid ejection head 3 is relatively reduced, this configuration can be suitably applied to a printing apparatus in which the inclination angle of the liquid ejection head 3 shown in fig. 52 is different for each liquid ejection head. Since the water head difference can be reduced, the negative pressure difference applied to the ejection ports of the printing element plate can be reduced even when the liquid ejection heads 3 having different inclination angles are used. Further, since the distance from the negative pressure control unit 230 to the printing element board 10 is reduced, the flow resistance therebetween is reduced. Therefore, the pressure loss difference due to the change in the liquid flow rate is reduced, and therefore the negative pressure can be more desirably controlled.

Fig. 55B is a schematic diagram showing the flow of the printing liquid inside the liquid ejection head 3. Although the circulation path is similar in terms of circuit to that shown in fig. 53, fig. 55B shows liquid flows in components of the actual liquid ejection head 3. A pair of a common supply channel 211 and a common recovery channel 212 extending in the longitudinal direction of the liquid ejection head 3 are provided inside the elongated second channel member 60. The common supply passage 211 and the common recovery passage 212 are formed so that the liquid flows therein in opposite directions, and a filter 221 is provided at the upstream side of each passage so as to capture foreign matter from the connection portion 111 and the like. In this way, since the liquid flows through the common supply channel 211 and the common recovery channel 212 in opposite directions, it is possible to desirably reduce the temperature gradient inside the liquid ejection head 3 in the longitudinal direction. To simplify the description of fig. 53, the flows in the common supply passage 211 and the common supply passage 212 are indicated by the same direction.

The negative pressure control unit 230 is connected to the downstream side of each of the common supply passage 211 and the common recovery passage 212. Further, a branch portion is provided on a route where the common supply passage 211 is connected to the single-use supply passage 213a, and a branch portion is provided on a route where the common recovery passage 212 is connected to the single-use recovery passage 213 b. The individual supply channel 213a and the individual recovery channel 213b are formed inside the first channel member 50, and each individual channel communicates with an opening 10A (see fig. 36C) of the cover member 20, the cover member 20 being provided on the back surface of the printing element plate 10.

The negative pressure control unit 230 indicated by "H" and "L" in fig. 55B is a unit on the high pressure side (H) and a unit on the low pressure side (L). The negative pressure control unit 230 is a back pressure type pressure adjusting mechanism that controls the upstream pressure of the negative pressure control unit 230 to a relatively high negative pressure (H) and a relatively low negative pressure (L). The common supply passage 211 is connected to the negative pressure control unit 230 (high pressure side), and the common recovery passage 212 is connected to the negative pressure control unit 230 (low pressure side), so that a pressure difference is generated between the common supply passage 211 and the common recovery passage 212. By virtue of this pressure difference, the liquid flows from the common supply passage 211 to the common recovery passage 212, sequentially passing through the single supply passage 213a, the ejection port 11 (pressure chamber 23) in the printing element plate 10, and the single recovery passage 213 b.

Fig. 55C is a sectional perspective view taken along the line LVC-LVC of fig. 55A. In this application example, each ejection module 200 includes the first channel member 50, the printing element board 10, and the flexible circuit board 40. In this application example, the support member 2030 (fig. 18) described in the second application example does not exist, and the printing element board 10 including the cover member 20 is directly joined to the first passage member 50. Liquid is supplied from the communication port 61 formed at the upper surface of the common supply passage 211 provided at the second passage member 60 to the single-use supply passage 213a via the single-use communication port 53 formed at the lower surface of the first passage member 50. Then, the liquid passes through the pressure chamber 23 and through the single recovery passage 213b, the single communication port 53, and the communication port 61, so as to be recovered to the common recovery passage 212.

Here, the difference from the second application example shown in fig. 40 is that: the single-use communication port 53 formed at the lower surface (the surface close to the second passage member 60) of the first passage member 50 is sufficiently large relative to the communication port 61 formed at the upper surface of the second passage member 50. With this configuration, even when positional deviation occurs when the ejection module 200 is mounted on the second channel member 60, the first channel member and the second channel member can be reliably brought into fluid communication with each other. As a result, the throughput of the print head manufacturing process is improved, and therefore the cost can be cut.

(other examples)

The present invention is not limited to the ink ejection substrate, the ink jet print head, and the ink jet printing apparatus, but can be widely applied to a liquid ejection substrate, a liquid ejection head, and a liquid ejection apparatus that eject various liquids. The present invention can also be applied to various types of printing apparatuses such as a full-line type and a serial scan type.

Further, the present invention can be widely applied to a liquid ejection apparatus using a liquid ejection head capable of ejecting various liquids, in addition to an ink jet printing apparatus that prints an image using an ink jet print head capable of ejecting ink. For example, the present invention can be applied to a printer, a copying machine, a facsimile machine having a communication system, a word processor having a printing section, and an industrial printing apparatus combined with various processing devices. Furthermore, the invention can be used for manufacturing biochips or printing electronic circuits.

According to the present invention, the plurality of supply paths, the plurality of recovery paths, the first common supply path, and the first common recovery path can be formed with high accuracy. Therefore, even when a plurality of ejection openings are densely arranged, the liquid can be circulated through the pressure chambers respectively corresponding to the ejection openings. As a result, satisfactory ejection performance of ejecting the liquid from the ejection port can be maintained. For example, in the case of ejecting ink from the ejection openings to print an image, it is possible to print a high-quality image with high accuracy by suppressing a drop in the ejection speed due to evaporation of moisture in the ink from the ejection openings.

While the present invention has been described with reference to the exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The following claims are to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. A liquid ejection head comprising:

an ejection opening array in which a plurality of ejection openings for ejecting liquid are arranged in a first direction;

a plurality of pressure chambers communicating with the ejection port, each of the plurality of pressure chambers having an energy generating element for generating energy for ejecting the liquid;

a plurality of supply channels extending in a second direction intersecting the first direction, the plurality of supply channels supplying liquid to the pressure chambers;

a plurality of recovery channels extending in the second direction and recovering the liquid from the pressure chamber;

a common supply channel extending in a first direction and supplying liquid to the plurality of supply channels; and

and a common recovery channel extending in the first direction and recovering the liquid from the plurality of recovery channels.

2. The liquid ejection head according to claim 1,

wherein a plurality of ejection port arrays are arranged along each other, and

wherein a common supply passage and a common recovery passage are provided for each ejection port array.

3. The liquid ejection head according to claim 1,

wherein the plurality of supply channels are arranged in a first direction.

4. The liquid ejection head according to claim 1,

wherein the plurality of recovery channels are arranged in a first direction.

5. The liquid ejection head according to claim 1,

wherein the length of the common supply passage corresponds to the length of the ejection port array.

6. The liquid ejection head according to claim 1,

wherein the length of the common recovery passage corresponds to the length of the ejection port array.

7. The liquid ejection head according to claim 1,

wherein the liquid ejection head includes a supply channel array in which the plurality of supply channels are arranged and a recovery channel array in which the plurality of recovery channels are arranged, and

the ejection port array is disposed between the supply passage array and the recovery passage array.

8. The liquid ejection head according to claim 1,

wherein the liquid ejection head includes a printing element substrate having the ejection port array, the pressure chamber, the plurality of supply channels, the plurality of recovery channels, the common supply channel, and the common recovery channel.

9. The liquid ejection head according to claim 8,

wherein the liquid ejection head is a wide-width type liquid ejection head, and

the plurality of printing element substrates are arranged in a line.

10. The liquid ejection head according to claim 9,

wherein, the printing element substrate is a parallelogram.

11. The liquid ejection head according to claim 2,

wherein the plurality of ejection port arrays include ejection port arrays that eject different kinds of liquids.

12. The liquid ejection head according to claim 8,

wherein the liquid ejection head includes a support member that supports the plurality of printing element substrates, and

the supporting member includes a second common supply path that supplies liquid to the plurality of printing element substrates and a second common recovery path that recovers liquid from the plurality of printing element substrates.

13. The liquid ejection head according to claim 12,

wherein the supporting member includes a single supply passage that supplies the liquid from the second common supply passage to the printing element substrate and a single recovery passage that recovers the liquid from the printing element substrate to the second common recovery passage.

14. The liquid ejection head according to claim 13,

wherein the single-use supply passage supplies the liquid from one end of the support member to a central portion of the support member in the short side direction, and

the single-use recovery passage recovers liquid from the center of the support member toward one end of the support member in the short-side direction.

15. The liquid ejection head according to claim 12,

wherein the liquid ejection head includes a first negative pressure control unit communicating with the second common supply passage and a second negative pressure control unit communicating with the second common recovery passage.

16. The liquid ejection head according to claim 1,

wherein the liquid supplied from the outside flows through the common supply passage, the pressure chamber, the recovery passage, and the common recovery passage in this order.

17. The liquid ejection head according to claim 13,

wherein the liquid supplied from the outside flows through the second common supply passage, the single-use supply passage, the common supply passage, the pressure chamber, the recovery passage, the common recovery passage, the single-use recovery passage, and the second common recovery passage in this order.

18. The liquid ejection head according to claim 1, wherein the liquid inside the pressure chamber circulates between the pressure chamber and the outside.

19. A liquid ejection head comprising:

an energy generating element array in which a plurality of energy generating elements for generating energy for ejecting liquid from a plurality of ejection ports are arranged in a first direction;

a substrate on which an array of energy generating elements is provided;

a plurality of supply channels extending in a second direction intersecting a face of the substrate on which the array of energy generating elements is provided, the plurality of supply channels supplying liquid to the energy generating elements;

a plurality of recovery channels extending along a second direction;

a common supply passage extending in a first direction and communicating with the plurality of supply passages; and

a common recovery passage extending in a first direction and communicating with the plurality of recovery passages,

wherein the liquid supplied from the outside flows through the common supply channel, the energy generating element, the recovery channel, and the common recovery channel in this order.

20. The liquid ejection head according to claim 19,

wherein the liquid ejection head includes a pressure chamber in which the energy generating element is disposed, and

the liquid inside the pressure chamber circulates between the pressure chamber and the outside.