Liquid ejection head, liquid ejection unit, and apparatus for ejecting liquid

Abstract

To provide a liquid discharge head that can suppress tensile stress generated in a piezoelectric body to improve reliability and can discharge large liquid droplets to improve discharge characteristics.SOLUTION: A liquid discharge head comprises a liquid chamber substrate, a vibration plate, a piezoelectric body 20, wiring and a nozzle substrate. The liquid chamber substrate has an individual liquid chamber 15 formed at a position opposing to the piezoelectric body across the vibration plate. The wiring is formed at a portion on the individual liquid chamber and is formed at least on a middle point of one side of a plurality of sides of the individual liquid chamber in a planar view. The middle point is defined as a base point. The individual liquid chamber and the piezoelectric body are formed in a polygonal shape constituted of four or more sides in the planar view. The distance from the base point to a middle point of the other side of the individual liquid chamber in the planar view is defined as a distance L. When the distance between an end part of the individual liquid chamber in the side in which the distance L is largest and an end part of the piezoelectric body is defined as A and the distance between an end part of the individual liquid chamber in the side in which the distance L is smallest and the end part of the piezoelectric body is defined as B, A<B is satisfied.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a liquid ejection head, a liquid ejection unit, and an apparatus for ejecting a liquid.

Background Art

[0002] In a liquid ejection head, a technique using a piezoelectric body as a drive source of an actuator is known.

[0003] Patent Document 1 discloses a nozzle plate, a liquid chamber substrate having individual liquid chambers and a droplet supply chamber, a diaphragm, and a droplet ejection head having a piezoelectric element. Further, in Patent Document 1, the width of the individual liquid chamber in the vicinity of the region where the nozzle is formed is formed wider than the width of other regions, and at least a reinforcing portion including an insulating film is formed on the piezoelectric element corresponding to the vicinity of the region where the nozzle is formed. According to Patent Document 1, it is said that droplets can be ejected stably and uniformly.

[0004] In the prior art, the individual liquid chambers and the piezoelectric body are often formed in a rectangular shape in a plan view. In this case, the diaphragm may be cracked due to stress on the diaphragm during long-term driving.

[0005] Patent Document 2 discloses an inkjet recording head including a piezoelectric element composed of a lower electrode, a piezoelectric layer, and an upper electrode via a diaphragm constituting a part of a pressure generation chamber communicating with a nozzle opening. Further, in Patent Document 2, the diaphragm in the region facing at least one end portion in the longitudinal direction of the piezoelectric active portion of the piezoelectric element is convex on the non-piezoelectric element formation surface side. According to Patent Document 2, it is said that generation of cracks due to stress concentration, fatigue failure, etc. can be prevented in the vicinity of the end portion of the piezoelectric active portion and the boundary between the pressure generation chamber and the peripheral wall.

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the prior art, insufficient consideration has been given to the shape of the individual liquid chambers and the piezoelectric body, and the tensile stress generated in the piezoelectric body has not been sufficiently suppressed. Therefore, during long-term driving, stress is generated on the diaphragm, causing a problem that the diaphragm cracks, and further solutions are required. For this reason, it is required to improve durability and reliability. However, when attempting to solve the problem of the diaphragm cracking due to stress on the diaphragm, the displacement amount of the diaphragm decreases, the ejected liquid droplets cannot be made larger, and a problem occurs in that good ejection characteristics cannot be obtained.

[0007] Therefore, an object of the present invention is to provide a liquid ejection head that can suppress the tensile stress generated in the piezoelectric body to improve reliability, can make the ejected liquid droplets larger, and can improve ejection characteristics.

Means for Solving the Problems

[0008] In order to solve the above problems, the liquid ejection head of the present invention includes a liquid chamber substrate, a diaphragm formed on the liquid chamber substrate, a lower electrode formed on the diaphragm, a piezoelectric body formed on the lower electrode, an upper electrode formed on the piezoelectric body, wiring for driving the piezoelectric body, and a nozzle substrate having a nozzle. The liquid chamber substrate has individual liquid chambers formed at positions facing the piezoelectric body with the diaphragm interposed therebetween. The wiring is formed on a part of the individual liquid chambers and is at least formed on the midpoint of one of the plurality of sides of the individual liquid chambers in a plan view. With the midpoint as a reference point, the individual liquid chambers and the piezoelectric body are polygons composed of four or more sides in a plan view. Let the distance from the reference point to the midpoint of the other side of the individual liquid chamber in the plan view be distance L, the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the largest be A, and the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the smallest be B. A < B It is characterized by satisfying the above. However, when there are a plurality of sides where distance L is the largest, the above formula is satisfied for all corresponding sides, and when there are a plurality of sides where distance L is the smallest, the above formula is satisfied for all corresponding sides.

Advantages of the Invention

[0009] According to the present invention, it is possible to provide a liquid ejection head that can suppress tensile stress generated in a piezoelectric body, improve reliability, increase the size of ejected droplets, and improve ejection characteristics.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 3B

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Figure 7

Figure 8

Figure 9A

Figure 9B

Figure 10A

Figure 10B

Figure 11

Figure 12

Figure 13

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Figure 15

Figure 16

Embodiments for Carrying Out the Invention

[0011] Hereinafter, a liquid discharge head, a liquid discharge unit, and an apparatus for discharging a liquid according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and as long as the functions and effects of the present invention are achieved in any aspect, it is included in the scope of the present invention.

[0012] (Liquid discharge head) The liquid discharge head of the present invention includes a liquid chamber substrate, a diaphragm formed on the liquid chamber substrate, a lower electrode formed on the diaphragm, a piezoelectric body formed on the lower electrode, an upper electrode formed on the piezoelectric body, wiring for driving the piezoelectric body, and a nozzle substrate having a nozzle. The liquid chamber substrate has individual liquid chambers formed at positions facing the piezoelectric body with the diaphragm interposed therebetween. The wiring is formed on a part of the individual liquid chambers and is at least formed on the midpoint of one side among a plurality of sides of the individual liquid chambers in a plan view. Taking the midpoint as a reference point, the individual liquid chambers and the piezoelectric body are polygons composed of four or more sides in a plan view. Let the distance from the reference point to the midpoint of the other side of the individual liquid chamber in the plan view be distance L, the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the largest be A, and the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the smallest be B. A < B It is characterized by satisfying However, when there are a plurality of sides with the largest distance L, the above formula is satisfied for all corresponding sides, and when there are a plurality of sides with the smallest distance L, the above formula is satisfied for all corresponding sides.

[0013] An example of the liquid ejection head of the present embodiment will be described. Here, an example in the case where the individual liquid chambers and the piezoelectric body are rectangular (rectangular) in plan view will be described. FIG. 1 is a schematic cross-sectional view of an example of the liquid ejection head of the present embodiment, and is a schematic cross-sectional view along the short side direction (Y direction) of the individual liquid chambers. FIG. 2 is a schematic cross-sectional view of an example of the liquid ejection head of the present embodiment, and is a schematic cross-sectional view along the long side direction (X direction) of the individual liquid chambers.

[0014] The liquid ejection head 1 of the present embodiment includes an actuator substrate 100 (liquid chamber substrate), a diaphragm 13 formed on the liquid chamber substrate, a lower electrode 10 formed on the diaphragm 13, a piezoelectric body 20 formed on the lower electrode 10, an upper electrode 11 formed on the piezoelectric body 20, a wiring 42 for driving the piezoelectric body 20, and a nozzle substrate 300 having a nozzle 16.

[0015] The actuator substrate 100 has individual liquid chambers 15 (also referred to as pressurized liquid chambers, liquid chambers, etc.) formed at positions facing the piezoelectric body 20 with the diaphragm 13 interposed therebetween.

[0016] The individual liquid chambers 15 communicate with the nozzle 16 and are provided in plural. Further, they are partitioned by a partition wall 14.

[0017] The piezoelectric body 20 and the electrode may be referred to as a piezoelectric element 12 or the like. As the piezoelectric body 20, for example, PZT (lead zirconate titanate) can be used, and the piezoelectric body 20 may be referred to as a PZT film, PZT, etc. The piezoelectric body 20 is sandwiched between the lower electrode 10 and the upper electrode 11, and the lower electrode 10 may be a common electrode, or the upper electrode 11 may be a common electrode. A voltage is applied by the wiring 42, and the piezoelectric element 12 generates liquid ejection energy.

[0018] In this embodiment, the actuator substrate 100 and the nozzle substrate 300 are joined together, and the individual liquid chambers 15 are formed by the actuator substrate 100 and the nozzle substrate 300. For joining the substrates, for example, an adhesive 49 can be used.

[0019] The support substrate 200 is joined to the actuator substrate 100, and a liquid supply port 66 is formed in the support substrate 200. A liquid (for example, a recording liquid, ink) is supplied from the outside through the liquid supply port 66, and is supplied from the common liquid supply path 19 and the common liquid chamber 18 to the individual liquid chambers 15 through the fluid resistance portion 17.

[0020] In the liquid ejection head 1 of this embodiment, for example, with the individual liquid chambers 15 filled with a liquid (recording liquid, ink), a pulse voltage is applied to the upper electrode 11 corresponding to the nozzle 16 that ejects ink based on the image data. As the pulse voltage, for example, a pulse voltage of 20 V can be selected, and the application of the pulse voltage is performed by, for example, an oscillation circuit. The wiring 42 is connected to the upper electrode 11 through a connection hole formed in the interlayer insulating film 45, and a pulse voltage is applied to the upper electrode 11 by the wiring 42.

[0021] By applying a voltage pulse, the piezoelectric body 20 contracts in a direction parallel to the diaphragm 13 due to the electrostriction effect. As a result, the diaphragm 13 bends in the direction of the individual liquid chamber 15. Thereby, the pressure in the individual liquid chamber 15 rapidly rises, and ink is ejected from the nozzle 16 communicating with the individual liquid chamber 15.

[0022] After the application of the pulse voltage, since the contracted piezoelectric body 20 returns to its original state, the bent diaphragm 13 returns to its original position. As a result, the inside of the individual liquid chamber 15 becomes a negative pressure compared to the inside of the common liquid chamber 18, and ink is supplied from the common liquid chamber 18 to the individual liquid chamber 15 through the fluid resistance portion 17. Also, the ink passes through the common liquid supply path 19 from the outside through the liquid supply port 66 and is supplied to the common liquid chamber 18.

[0023] By repeating the above, droplets can be continuously ejected, and an image is formed on a recording medium disposed opposite to the liquid ejection head. The recording medium is also referred to as a medium to be recorded, a medium, etc. For example, in addition to plain paper, a non-permeable recording medium or the like can be used.

[0024] <Example 1> Next, an example of the liquid ejection head of the present embodiment will be further described with reference to a plan view and the like. FIG. 3A is a schematic plan view of a main part of an example of the liquid ejection head of the present embodiment, and is a diagram for explaining the configuration when viewed from a direction perpendicular to the lamination direction of each layer of the piezoelectric element 12.

[0025] As shown in FIG. 3A, the individual liquid chambers 15 in the present embodiment are rectangular (rectangular) in plan view, and have two short sides facing each other and two long sides facing each other. In the figure, the center of the individual liquid chamber 15 is indicated by O, the longitudinal direction of the individual liquid chamber 15 is the X axis, and the short side direction is the Y axis. FIG. 1 is a schematic cross-sectional view along the short side direction (Y-axis direction) of the individual liquid chamber 15, and FIG. 2 is a schematic cross-sectional view along the longitudinal direction (X-axis direction) of the individual liquid chamber 15.

[0026] Note that the shape of the individual liquid chamber 15 in plan view is not limited to a rectangular shape, and any polygon may be used. When it is rectangular, there is an advantage that it is easy to form the individual liquid chamber 15.

[0027] In the illustrated individual liquid chamber 15, the short sides facing each other are indicated by side 15-1 and side 15-2. Also, the long sides facing each other are indicated by side 15-3 and reference numeral 15-4. In the present embodiment, a wiring 42 is formed on one side (side 15-2 side) of the two short sides of the individual liquid chamber 15 (see also FIG. 2). The side 15-2 side may be referred to as one side of the short side, and the side 15-1 side may be referred to as the other side of the short side.

[0028] Note that in the figure, the wiring 42 is shown by a broken line, and the illustrated wiring 42 is shown schematically. Therefore, the shape and the like of the wiring 42 are not limited to those shown.

[0029] In this embodiment, the area where the individual liquid chambers 15 are formed is larger than the area where the piezoelectric body 20 is formed. Such a relationship is also illustrated in FIGS. 1 and 2.

[0030] The wiring 42 is formed on a part of the individual liquid chamber 15. Further, the wiring 42 is formed at least on the midpoint of one of the plurality of sides of the individual liquid chamber 15 in a plan view, and the midpoint is used as a base point bp (base point). In the figure, the midpoints of the three sides (the sides excluding the side having the base point bp) of the individual liquid chamber 15 are represented by mp1, mp3, and mp4. Note that mp represents middle point. Since mp2 corresponds to bp, it is not shown in the figure.

[0031] FIG. 3B is a schematic plan view for explaining the distance L from the base point bp to the midpoint mp of the side of the individual liquid chamber 15. In this embodiment, the distance from the base point bp to the midpoint of the other side of the individual liquid chamber 15 in a plan view is defined as the distance L. The other side of the individual liquid chamber 15 means excluding the side having the base point bp. As shown in the figure, the distance L from the base point bp to the side 15-1 is indicated as L1, the distance L from the base point bp to the side 15-3 is indicated as L3, and the distance L from the base point bp to the side 15-4 is indicated as L4.

[0032] In this embodiment, the side with the largest distance L and the side with the smallest distance L are found. And it is important that the distances between the ends of the individual liquid chamber 15 and the ends of the piezoelectric body 20 at the side with the largest distance L and the side with the smallest distance L satisfy a predetermined relationship.

[0033] In this embodiment, the distance between the end of the individual liquid chamber 15 and the end of the piezoelectric body 20 at the side with the largest distance L is defined as A, and the distance between the end of the individual liquid chamber 15 and the end of the piezoelectric body 20 at the side with the smallest distance L is defined as B. In this example, the side with the largest distance L corresponds to the side 15-1, which is one of the two short sides of the individual liquid chamber 15. Also, in this example, the sides with the smallest distance L correspond to the sides 15-3 and 15-4, which are the long sides of the individual liquid chamber 15.

[0034] In this example, although the wiring 42 is formed on the short side 15-2 of the individual liquid chamber 15, it is not limited to this. The wiring 42 may be formed on the long side 15-3 or the side 15-4 of the individual liquid chamber 15. In this case, the midpoint mp3 of the side 15-3 or the midpoint mp4 of the side 15-4 becomes the reference point bp, and the distance L from the reference point bp to the midpoint of the other side of the individual liquid chamber 15 is considered.

[0035] FIG. 4 is an enlarged view of the broken line a in FIG. 3A. As shown, the end of the piezoelectric body 20 is indicated by reference numeral 20a, and the end of the liquid chamber 15 is indicated by reference numeral 15a. As shown, the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on the other side (side 15-1 side) of the two short sides of the individual liquid chamber 15 is defined as A. Also, the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on one side (side 15-3 side) of the two long sides of the individual liquid chamber 15 is defined as B1, and the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on the other side (side 15-4) of the long side is defined as B2.

[0036] In addition, when the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on one side of the individual liquid chamber 15 varies depending on the location, an average value may be obtained from the numerical values at a plurality of locations, and this average value may be used as the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber. In other words, A and B may be average values.

[0037] The relationship between A and B in this embodiment is A < B which is satisfied. By satisfying such a relationship, tensile stress is not applied to the piezoelectric body 20, and the reliability can be enhanced. Furthermore, the size of the ejected droplets can be increased.

[0038] Also in this embodiment, as in this example, there may be a plurality of sides where the distance L is the smallest. In this example, the sides 15-3 and 15-4 correspond to the sides where the distance L is the smallest. In this case, the above formula is satisfied for all the corresponding sides. That is, A < B1 and A < B2 are satisfied. Note that there may be a plurality of sides with the largest distance L. In this case, A < B shall be satisfied for all corresponding sides.

[0039] As a result of intensive studies, the inventor of the present invention has found that the above effects can be obtained by satisfying the above relationship between A and B, leading to the present invention. This will be described below.

[0040] In this example, the individual liquid chamber is rectangular (rectangular) in plan view, and wiring is formed on one side of the two short sides. In this case, the displacement distribution showing the displacement of the diaphragm in the longitudinal direction (X-axis direction) becomes asymmetric. This displacement distribution depends not only on the presence or absence of wiring but also on the distance between the end of the piezoelectric body and the end of the individual liquid chamber. The wider the portion of the diaphragm where the individual liquid chamber is open and the piezoelectric body does not exist, the greater the displacement of the diaphragm.

[0041] FIG. 5 is a diagram showing an example of the displacement distribution of the diaphragm when a certain voltage is input. The horizontal axis is the distance [μm] from the center O of the individual liquid chamber in the longitudinal direction (X-axis direction) of the individual liquid chamber, and the vertical axis is the displacement [μm] of the diaphragm. As shown in the figure, the displacement distribution of the diaphragm is asymmetric. This is due to, for example, wiring being formed on one side of the short side of the individual liquid chamber.

[0042] Also, in FIG. 5, the displacement distribution when the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on the other side (side 15-1 side) of the short side of the individual liquid chamber 15, that is, A, is changed is shown. Here, the displacement distributions when A is changed to 1.5 μm, 4.5 μm, and 9.5 μm are shown. As the value of A increases, the displacement of the diaphragm becomes larger in the vicinity of -50 μm to -120 μm. That is, in these three examples, the displacement of the diaphragm is the largest when A = 9.5 μm.

[0043] It is considered that as the distance between the end of the piezoelectric body and the end of the individual liquid chamber increases, the longitudinal stress on the diaphragm becomes less likely to be applied, and the displacement of the diaphragm increases. However, as the displacement of the diaphragm increases, the tensile stress generated in the piezoelectric body increases, making it difficult to improve the durability of the piezoelectric body. If the durability of the piezoelectric body cannot be improved, the reliability of the liquid ejection head cannot be enhanced. Therefore, it is necessary to suppress the value of A to a certain extent.

[0044] On the other hand, in order to improve the printing area with respect to the same driving time, it is preferable that the ejection droplet volume is large, and if the ejection droplet volume is large, the ejection characteristics can be improved. The distance between the end of the piezoelectric body and the end of the individual liquid chamber also affects the size of the ejection droplet volume. As the distance between the end of the piezoelectric body and the end of the individual liquid chamber increases, the displacement of the diaphragm increases, so the ejection droplet volume increases. Therefore, also from the viewpoint of the ejection droplet volume, it is required to appropriately select the distance between the end of the piezoelectric body and the end of the individual liquid chamber.

[0045] However, as described above, regarding the distance A between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber on the other side of the short side of the individual liquid chamber 15 (side 15-1 side), that is, A, it is preferable not to make it too large from the viewpoint of suppressing the tensile stress. In other words, it is preferable not to make the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the longitudinal direction (X-axis direction) too large.

[0046] Also, although it may not be easy to understand in Fig. 5, the smaller the value of A, the closer the maximum point of displacement is to the longitudinal center (X = 0), and the asymmetry is reduced. For example, when A = 1.5 μm, the location of the maximum displacement is around -50 μm, and a similar displacement distribution is obtained on the left and right sides with the location of the maximum displacement as the boundary. In contrast, when A = 9.5 μm, the location of the maximum displacement is around -80 μm, and the difference in displacement distribution between the left and right sides with the location of the maximum displacement as the boundary is larger than that when A = 1.5 μm. Therefore, the asymmetry is reduced more when A = 1.5 μm than when A = 9.5 μm. An increase in asymmetry leads to bending of the ejected droplets. Also from this perspective, it is preferable that the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the longitudinal direction (X-axis direction) is not made too large.

[0047] Therefore, for the purpose of ensuring the ejected droplet volume, rather than increasing the distance between the end of the piezoelectric body and the end of the individual liquid chamber in the longitudinal direction, it is preferable to achieve the above object by another configuration. Thus, we considered adjusting the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short direction (Y-axis direction). The distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short direction (Y-axis direction) is considered to be less likely to affect the displacement of the diaphragm in the longitudinal direction, so it is considered possible to adjust the value to ensure the ejected droplet volume.

[0048] The inventor of the present invention prepared various samples and conducted measurements and investigations. Fig. 6 is a diagram showing an example of the relationship between the size of the ejected droplet volume when the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short direction (Y-axis direction) is changed. The horizontal axis represents the distance [μm] between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short direction. The vertical axis represents the relative difference in the ejected droplet volume from when the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short direction is 6.5 μm and the ejected droplet volume is set to 100%.

[0049] Note that the horizontal axis in Fig. 6 corresponds to B1 or B2 in Fig. 4. Also, in Fig. 6, the results were measured with B1 = B2.

[0050] As shown in the figure, the larger the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short side direction, the larger the discharge droplet volume. This is presumably because as the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short side direction increases, the displacement of the diaphragm in the short side direction increases, and the appropriate discharge amount (the size of the discharge droplet) increases. The inventor further examined how much larger the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber in the short side direction should be in order to obtain a satisfactory appropriate discharge amount.

[0051] Regarding the distance between the end 20a of the piezoelectric body and the end 15a of the individual liquid chamber, specific numerical values were also considered and examined. As a result, as described above, it was found that by satisfying the relationship of A < B between A and B, the desired effect can be obtained. By satisfying the above relationship, it was found that tensile stress can be not applied to the piezoelectric body 20 or the tensile stress can be reduced, so that the durability of the piezoelectric body 20 can be enhanced and the reliability can be enhanced. Furthermore, it was found that by satisfying the above relationship, the discharge droplet volume can be increased and the discharge characteristics can be improved. According to the present embodiment, cracking of the diaphragm can be suppressed, the discharge droplet volume can be increased, and improvement in reliability and improvement in discharge characteristics can be realized simultaneously. Also, since the asymmetry of the displacement distribution in the longitudinal direction can be reduced, discharge deflection can be reduced, and the discharge characteristics can be improved from this viewpoint as well.

[0052] When A ≥ B, the tensile stress generated in the piezoelectric body becomes large, good reliability cannot be obtained, and the discharge droplet volume cannot be increased. Also, as in this example, when there are two sides where the distance L is the smallest, if A ≥ B1 or A ≥ B2, similarly good results cannot be obtained. It is necessary that both B1 and B2 satisfy the relationship of A < B.

[0053] In this embodiment, the lower limit value of A is not particularly limited. For example, considering the alignment deviation during each layer patterning, it is preferably 1 μm or more. In this case, by overlapping the piezoelectric body and the individual liquid chamber, it is possible to prevent a decrease in reliability caused by stress being applied to the brittle piezoelectric body.

[0054] In this embodiment, the upper limit value of B is not particularly limited. For example, it is preferably 20 μm or less. In this case, it is possible to prevent a decrease in the pressure generating force due to a decrease in the area of the piezoelectric body.

[0055] When there are a plurality of sides where the distance L is the smallest, it is preferable that each value of B is the same or substantially the same. For example, in the above example, it is preferable that B1 and B2 have the same value or substantially the same value. In this case, the displacement distribution of the diaphragm in the short side direction can be made symmetric, and the variation in the stress in the short side direction generated in the piezoelectric body can be suppressed. Thereby, the reliability can be further improved.

[0056] In addition, when there are a plurality of sides where the distance L is the largest, it is preferable that each value of A is the same or substantially the same. For example, when represented as A1, A2, etc., it is preferable that A1 and A2 have the same value or substantially the same value. In this case, the variation in the pressure generated in the piezoelectric body can be suppressed, and the reliability can be further improved.

[0057] In this embodiment, in a plan view (for example, FIGS. 3A and 3B), it is preferable that the corners of the individual liquid chamber 15 and the piezoelectric body 20 have a curved shape. By making the corners of the individual liquid chamber 15 and the piezoelectric body 20 into a curved shape in this way, the stress can be dispersed and the reliability can be improved. Note that the corner refers to the portion where two sides are connected.

[0058] Regarding one of the corners of the individual liquid chamber 15, when the average value of the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having a curved shape is defined as C, When there is a corner where the side having A and the side having B are connected, the corner is, A < C < B Preferably, this condition is satisfied. By doing so, the stress load at the corners of the piezoelectric body can be alleviated, and the reliability during long-term driving can be improved.

[0059] In this example, as shown in FIG. 3A, the side having the A corresponds to side 15-1, and the sides having the B correspond to side 15-3 and side 15-4. Therefore, it is preferable that both the corner where side 15-1 and side 15-3 are connected and the corner where side 15-1 and side 15-4 are connected satisfy A < C < B.

[0060] Supplementary explanation about satisfying A < C < B. Regarding the corner where the side having the A and the side having the B are connected, for this A and this B, it is only necessary to satisfy A < C < B. In other words, for example, even if another A or B different from the two sides of this corner does not satisfy the above formula. This will be explained with reference to FIG. 4. When C at the corner where side 15-1 and side 15-3 are connected is denoted as C11, if A < C11 < B1, the above-mentioned desired effect can be obtained. At this time, it is more preferable that A < C11 < B2, but the above effect can still be obtained even if A < C11 < B2 is not satisfied. Similarly, for the corner where side 15-1 and side 15-4 are connected, if A < C12 < B2, the above-mentioned desired effect can be obtained, and it is more preferable that A < C12 < B1.

[0061] In addition, as will be described later, when there is no corner where the side having the A and the side having the B are connected, it is preferable that all the corners of the individual liquid chamber 15 excluding the corners having the side with the reference point bp as one side satisfy A < C < B.

[0062] Regarding the above C, it will be explained with reference to FIG. 7. FIG. 7 is an enlarged view of the broken line b in FIG. 3A, and shows an enlarged and schematic view of one corner. As shown in the figure, the end of the piezoelectric body 20 is denoted by reference numeral 20a, and the end of the liquid chamber 15 is denoted by reference numeral 15a. Also, the portion having a curved shape at the corner is denoted by reference numeral W.

[0063] In this embodiment, since A < B, it is assumed that the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape varies depending on the location. In the figure, for the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape, for example, C1, C2, and C3 are illustrated. In this example, from B1 toward A, that is, in the order of C1, C2, and C3, it becomes smaller. In this example, for example, the average value is obtained by C1, C2, and C3, and this average value is set as C (specifically C11), and it is compared with A, B1, and B2. Note that the number of measurement locations for the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 when obtaining the average value can be appropriately changed.

[0064] Thus, when the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape differs depending on the location, it is preferable to obtain the average value and compare it with A, B1, and B2.

[0065] Also, in this embodiment, in the individual liquid chamber 15, a connection portion with a flow path communicating with the common liquid chamber 18 is formed, and there is a preferable location for the arrangement of this connection portion. That is, it is preferable that the connection portion 15b is formed at the central portion of one of the sides facing the side having the reference point bp in the individual liquid chamber 15, or at the corner portion where the two sides facing the side having the reference point bp in the individual liquid chamber 15 are connected. In this case, the stress applied to the diaphragm 13 of the side facing the side having the reference point bp in the individual liquid chamber 15 can be dispersed, and the occurrence of damage can be suppressed.

[0066] This will be described with reference to FIG. 8. FIG. 8 is a schematic plan view similar to FIG. 3A. In the figure, wiring 42 is formed on one side (side 15-2 side) of the two short sides of the individual liquid chamber 15, and side 15-2 is the side having the reference point bp. In this example, the connection portion 15b with the flow path 68 communicating with the common liquid chamber 18 is formed at the central portion of the side 15-1 facing the side 15-2 having the reference point bp in the individual liquid chamber 15. The connection portion 15b is formed, for example, by opening the partition wall of the individual liquid chamber 15.

[0067] In this example, the flow path 68 corresponds to the position of the fluid resistance portion 17. Further, the central portion means that, in other words, the distance from the X-axis passing through the center O of the individual liquid chamber 15 to the end of the connecting portion 15b in the Y-axis direction is equal on the upper side and the lower side in the Y-axis direction.

[0068] Regarding the preferable location where the connecting portion 15b is formed, another expression is also possible. When the shape of the individual liquid chamber 15 in plan view is an N-sided polygon represented by an integer N of 4 or more, when N is an even number, it is preferable that a connecting portion with the flow path 68 communicating with the common liquid chamber 18 is formed at the central portion of the side opposite to the side having the reference point bp in the individual liquid chamber 15. Further, when N is an odd number, it is preferable that a connecting portion with the flow path 68 communicating with the common liquid chamber 18 is formed at the corner portion where two sides among the sides opposite to the side having the reference point bp in the individual liquid chamber 15 are connected.

[0069] As in this example, when the shape of the individual liquid chamber 15 is rectangular in plan view, the side opposite to the side having the reference point bp is one, but when the shape of the individual liquid chamber 15 is polygonal, the side opposite to the side having the reference point bp may not be one. Therefore, it is described as one of the opposite sides.

[0070] <Manufacturing Example of Liquid Discharge Head> Next, a manufacturing example of the liquid discharge head of the present embodiment will be described. (a) A diaphragm 13 is formed on a silicon single crystal substrate with a plane orientation (110) (for example, a plate thickness of 400 μm) as the actuator substrate 100. As the diaphragm 13, for example, it is preferable to have a structure in which three layers of a silicon oxide film, a silicon nitride film, and an amorphous layer are laminated. At this time, the silicon oxide film exhibits compressive stress, and the silicon nitride film exhibits tensile stress. As a manufacturing method of the diaphragm 13, for example, the LP-CVD method can be used. The film thickness of the diaphragm 13 can be appropriately selected so that the stress becomes a desired value.

[0071] As the amorphous layer, for example, a silicon oxide film or alumina is preferable. In these cases, it becomes easier to trap Pb contained in the PZT formed on the upper part. From the viewpoint of surely preventing Pb diffusion, the film thickness of the amorphous layer is preferably 40 nm or more.

[0072] Next, on the diaphragm 13, a lower electrode 10 made of, for example, TiO2 and Pt is formed by sputtering to a thickness of 20 nm and 160 nm, respectively.

[0073] (b) Next, as the piezoelectric body 20, PZT is formed on the lower electrode 10 in multiple steps by, for example, spin coating, and finally a film with a thickness of 2 μm is formed. Then, an upper electrode 11 made of SRO and Pt is formed by sputtering to a thickness of 40 nm and 100 nm, respectively.

[0074] The method of forming the piezoelectric body 20 is not limited to the sol-gel method using spin coating, and for example, it may be formed by sputtering, ion plating, aerosol method, inkjet method, or the like.

[0075] Here, as an example, the method in the case of forming a film by the sol-gel method is shown. First, PbTiO3 is formed by spin coating as a seed layer for controlling the orientation of PZT. Further, a PZT precursor is formed by spin coating. At this time, the drying temperature of the PZT precursor is 120 °C, the pre-firing temperature is 380 °C, and the main firing temperature is 700 °C. These temperatures can be appropriately changed.

[0076] Then, by the lithography etching method, the piezoelectric element 12 and the upper electrode 11 are formed at positions corresponding to the individual liquid chambers 15 to be formed later. Also, the piezoelectric element 12 is formed at a position corresponding to the joint portion 48.

[0077] (c) Next, an interlayer insulating film 45 is formed to insulate the lower electrode 10, the piezoelectric body 20, and the lead-out wiring 42 to be formed later. The interlayer insulating film 45 is formed, for example, into a 1000-nm-thick SiO2 film by the plasma CVD method. The interlayer insulating film may be a film other than SiO2 of the plasma CVD method as long as it is a film having insulating properties and does not affect the piezoelectric element 12 or the electrode material.

[0078] Next, a connection hole for connecting the upper electrode 11 and the lead wiring 42 is formed by the litho-etching method. Although not shown here, when the lower electrode 10 is also connected to the lead wiring 42, a connection hole is formed in the same manner.

[0079] (d) Next, as the wiring 42, for example, TiN / Al is formed into films with thicknesses of 30 nm / 3 μm respectively by the sputtering method. Pt, which is the material of the upper electrode 11 or the lower electrode 10, directly contacts Al, which is the material of the lead wiring 42, at the bottom of the connection hole and is alloyed by the thermal history in the subsequent process. Therefore, TiN is applied as a barrier layer to prevent alloying in order to prevent film peeling or the like due to stress caused by volume change.

[0080] Also, the wiring 42 is formed at a location that will become the joint portion 48 with the support substrate 200 later.

[0081] (e) Next, as the passivation film 50, for example, a 1000-nm-thick silicon nitride film is formed by the plasma CVD method.

[0082] (f) Next, by the litho-etching method, the lead wiring pad portion 41 of the lead wiring 42, the actuator portion, and the openings of the common liquid supply path 19 are formed.

[0083] (g) Next, by the litho-etching method, the diaphragm 13 at the location that will become the common liquid chamber 18 later in the common liquid supply path 19 is removed.

[0084] (h) Next, a countersink 67 is provided by the litho-etching method at a position corresponding to the actuator portion to form the main flow liquid chamber and the branch flow liquid chamber. Thereby, the support substrate 200 is manufactured. At this time, for example, Si processing is performed by the dry etching method.

[0085] Next, the support substrate 200 and the actuator substrate 100 are joined with an adhesive 49 via the joint portion 48. The adhesive is applied to the support substrate 200 side to a thickness of about 1 μm by a general thin film transfer device.

[0086] Next, the actuator substrate 100 is polished by a known technique so as to have a desired thickness t (for example, a thickness of 80 μm) in order to form the individual liquid chambers 15, the common liquid chamber 18, and the fluid resistance portion 17. Instead of the polishing method, etching or the like may also be used.

[0087] (i) Next, by the lithography method, the partition walls other than the individual liquid chambers 15, the common liquid chamber 18, and the fluid resistance portion 17 are coated with a resist. Then, the individual liquid chambers 15, the common liquid chamber 18, and the fluid resistance portion 17 are formed by dry etching using an ICP etcher. Also, a lead-out wiring 42 for supplying a voltage to the upper electrode 11 is formed on one end portion (15-2 side) in the longitudinal direction.

[0088] In the above, as shown in FIG. 4 and the like, the individual liquid chambers 15 and the piezoelectric body 20 are formed so as to satisfy A < B1 and A < B2. Also, as a preferable configuration example in the present embodiment, the four corners of the individual liquid chamber 15 have a curved shape, and the piezoelectric body 20 is formed so as to have four corners each having a curved shape corresponding to the corners of the individual liquid chamber 15.

[0089] (j) Next, a nozzle substrate 300 having nozzles 16 opened at positions corresponding to the respective individual liquid chambers 15 formed separately is joined. By doing so, the liquid ejection head 1 can be manufactured.

[0090] <Example 2> Next, another example of the present embodiment will be described. Descriptions of matters similar to those in the above embodiment will be omitted. In the above embodiment, the shapes of the individual liquid chambers 15 and the piezoelectric body 20 in plan view are rectangular, but the present invention is not limited to this, and the individual liquid chambers 15 and the piezoelectric body 20 are polygons having four or more sides in plan view.

[0091] Fig. 9A shows an example in which the individual liquid chamber 15 and the piezoelectric body 20 are pentagonal in plan view. As shown, the individual liquid chamber 15 in this example has sides 15-11 to 15-15 as five sides. The midpoint of side 15-15 is used as the base point bp, and the midpoints of the other sides are denoted as mp11 to mp14. The distances (distance L) from the base point bp to the midpoints of the other sides of the individual liquid chamber 15 are indicated by L11 to L14.

[0092] In this example, the sides where the distance L is the largest are sides 15-11 and 15-12, and the sides where the distance L is the smallest are sides 15-13 and 15-14. In this example, the distance between the end of the individual liquid chamber 15 on side 15-11 and the end of the piezoelectric body 20 is denoted as A11, and the distance between the end of the individual liquid chamber 15 on side 15-12 and the end of the piezoelectric body 20 is denoted as A12. Also, the distance between the end of the individual liquid chamber 15 on side 15-13 and the end of the piezoelectric body 20 is denoted as B13, and the distance between the end of the individual liquid chamber 15 on side 15-12 and the end of the piezoelectric body 20 is denoted as B14.

[0093] In this example, the relationship between A and B is such that A < B is satisfied for all corresponding sides. That is, A11 < B13 A11 < B14 A12 < B13 A12 < B14 are all satisfied. In this case, the intended effects described in the above embodiment can be obtained.

[0094] Also in this example, there may be one side where the distance L is the largest, or there may be one side where the distance L is the smallest. For example, when L11 > L12, the side where the distance L is the largest is only side 15-1. Also, when L13 > L14, the side where the distance L is the smallest is only side 15-4. When L11 > L12 and L13 > L14, it is sufficient to satisfy A11 < B14. Conversely, when L11 < L12 and L13 < L14, it is sufficient to satisfy A12 < B13. Note that when the shape of the individual liquid chamber 15 is pentagonal, the existence of a plurality of A and B is in the case of a regular pentagon.

[0095] Also in this example, similar to the above example, it is preferable that the corners of the individual liquid chambers 15 and the piezoelectric body 20 have a curved shape. Also in this example, it is preferable that the average value C of the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape satisfies A < C < B.

[0096] In this example, since there is a corner where the side having A and the side having B are connected, in this case, it is preferable that the corner satisfies A < C < B. That is, at the corner where the side 15-11 having A11 and the side 15-13 having B13 are connected, the average value C13 of the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape preferably satisfies A11 < C13 < B13.

[0097] Also, at the corner where the side 15-12 having A12 and the side 15-14 having B14 are connected, the average value C14 of the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape preferably satisfies A12 < C14 < B14.

[0098] Also, at the corner where the side 15-11 having A11 and the side 15-13 having B13 are connected, the above-described intended effect can be obtained by satisfying A11 < C13 < B13. Therefore, although it is more preferable to satisfy A11 < C13 < B14 or A12 < C13 < B13, even if these are not satisfied, it is a preferable configuration.

[0099] In this example, when forming the connection portion 15b with the flow path 68 communicating with the common liquid chamber 18 in the individual liquid chamber 15, it is preferable that the connection portion 15b is formed at the corner where two sides (side 15-11 and side 15-12) among the sides facing the side 15-15 having the reference point bp in the individual liquid chamber 15 are connected. Fig. 9B shows a schematic plan view for explaining an example when the connection portion 15b is formed in this example. As shown in the figure, the connection portion 15b is formed at the corner where two sides among the sides facing the side 15-15 having the reference point bp in the individual liquid chamber 15 are connected (the corner where side 15-11 and side 15-12 are connected).

[0100] <Example 3> Next, another example of the present embodiment will be described. FIG. 10A shows an example in which the individual liquid chamber 15 and the piezoelectric body 20 are hexagonal in plan view. As shown in the figure, the individual liquid chamber 15 in this example has sides 15-21 to 15-26 as six sides. The midpoint of side 15-26 is used as the base point bp, and the midpoints of the other sides are mp21 to mp25. The distances (distance L) from the base point bp to the midpoints of the other sides of the individual liquid chamber 15 are indicated by L21 to L25.

[0101] In this example, the side with the largest distance L corresponds to side 15-21, and the sides with the smallest distance L correspond to sides 15-24 and 15-25. In this example, the distance between the end of the individual liquid chamber 15 and the end of the piezoelectric body 20 on side 15-21 is designated as A21. Also, the distance between the end of the individual liquid chamber 15 and the end of the piezoelectric body 20 on side 15-24 is designated as B24, and the distance between the end of the individual liquid chamber 15 and the end of the piezoelectric body 20 on side 15-25 is designated as B25.

[0102] In this example, the relationship between A and B is set such that A < B is satisfied for all corresponding sides. That is, A21 < B24 A21 < B25 are all satisfied. In this case, the intended effects described in the above embodiment can be obtained.

[0103] Also in this example, there may be one side with the largest distance L, or there may be one side with the smallest distance L.

[0104] Also in this example, similar to the above embodiment, it is preferable that the corners of the individual liquid chamber 15 and the piezoelectric body 20 have a curved shape. Also in this example, it is preferable that the average value C of the distance between the end of the piezoelectric body 20 and the end of the individual liquid chamber 15 in the portion having the curved shape satisfies A < C < B.

[0105] In this example, since there is no corner where the side having A and the side having B are connected, in this case, it is preferable that all the corners of the individual liquid chamber 15 excluding the corner having the side 15-26 with the base point bp as one side satisfy A < C < B.

[0106] Note that the corners having the side 15-26 with the base point bp as one side correspond to the corner where the side 15-24 and the side 15-26 are connected (lower left of the paper surface) and the corner where the side 15-25 and the side 15-26 are connected (lower right of the paper surface). It is preferable that all four corners excluding these two corners satisfy A < C < B.

[0107] For example, A21 < C22 < B24 ··· (1) A21 < C24 < B24 ··· (2) A21 < C23 < B25 ··· (3) A21 < C25 < B25 ··· (4) It is preferable that all of them are satisfied. However, the statement that all the corresponding corners satisfy A < C < B is not limited to the case where all of (1) to (4) are satisfied. For example, A21 < C22 < B25 ··· (5) A21 < C24 < B25 ··· (6) A21 < C23 < B24 ··· (7) A21 < C25 < B24 ··· (8) is also a preferable configuration when all of them are satisfied. If all the corresponding corners have the relationship of A < C < B, the desired effect can be obtained.

[0108] Also, when forming the connection portion 15b with the flow path 68 communicating with the common liquid chamber 18 in the individual liquid chamber 15, it is preferable to be the same as in FIG. 8. That is, it is preferable that the connection portion 15b is formed at the central portion of the side 15-21 facing the side 15-26 having the base point bp in the individual liquid chamber 15. FIG. 10B shows a schematic plan view for explaining an example when the connection portion 15b is formed in this example. As shown in the drawing, the connection portion 15b is formed on the side 15-21 facing the side 15-26 having the base point bp in the individual liquid chamber 15.

[0109] (Apparatus for ejecting liquid, liquid ejection unit) Next, an example of the apparatus for ejecting liquid according to the present embodiment will be described by taking an inkjet recording apparatus as an example. FIGS. 11 and 12 show the inkjet recording apparatus 90 of this example. This inkjet recording apparatus 90 has, for example, a carriage 98, a liquid ejection head 1, a printing mechanism unit 91, etc. The carriage 98 is movable in the scanning direction inside the apparatus main body. The liquid ejection head 1 can use the liquid ejection head of the above-described present embodiment and is mounted on the carriage 98, for example. The printing mechanism unit 91 is composed of an ink cartridge 99 that supplies ink to the liquid ejection head 1.

[0110] A paper feed cassette 93 (or a paper feed tray may also be used) capable of loading a large number of sheets of paper 92 from the front side is detachably attached to the lower part of the apparatus main body. Further, it may have a manual feed tray 94 that is opened for manually feeding the paper 92. The paper 92 fed from the paper feed cassette 93 or the manual feed tray 94 is taken in, and a required image is recorded by the printing mechanism unit 91. After that, it is discharged to the discharge tray 95 attached to the rear side.

[0111] The printing mechanism unit 91 holds the carriage 98 slidably in the main scanning direction by a main guide rod 96 and a sub-guide rod 97, which are guide members horizontally mounted on left and right side plates (not shown). A plurality of liquid ejection heads 1 for ejecting ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk) are mounted on this carriage 98 with a plurality of ink ejection ports (nozzles) arranged in a direction intersecting the main scanning direction and the ink droplet ejection direction directed downward. Further, each ink cartridge 99 for supplying ink of each color to the liquid ejection head 1 is detachably mounted on the carriage 98.

[0112] The ink cartridge 99 is provided with an air vent that communicates with the atmosphere upward and a supply port that supplies ink to the liquid ejection head 1 downward. Inside the ink cartridge 99, there is a porous body filled with ink, and the capillary force of the porous body maintains the ink supplied to the liquid ejection head 1 at a slight negative pressure.

[0113] As the liquid ejection head 1, liquid ejection heads 1 of various colors are used, but it may also be one liquid ejection head having nozzles for ejecting ink droplets of various colors.

[0114] The carriage 98 is slidably fitted onto the main guide rod 96 on the rear side (downstream side of paper conveyance), and is slidably placed on the sub-guide rod 97 on the front side (upstream side of paper conveyance). To move and scan the carriage 98 in the main scanning direction, a timing belt 104 is stretched between a drive pulley 102 and a driven pulley 103 that are rotationally driven by a main scanning motor 101. This timing belt 104 is fixed to the carriage 98, and the carriage 98 is reciprocally driven by the forward and reverse rotation of the main scanning motor 101.

[0115] In order to convey the paper 92 set in the paper feed cassette 93 downward to the liquid ejection head 1, the apparatus of this example has a paper feed roller 105, a friction pad 106, a guide member 107, a conveyance roller 108, and a tip roller 110.

[0116] The paper feed roller 105 and the friction pad 106 separate and feed the paper 92 from the paper feed cassette 93. The guide member 107 guides the paper 92. The conveyance roller 108 reverses and conveys the fed paper 92. The tip roller 110 defines the feeding angle of the conveyance roller 109 pressed against the circumferential surface of the conveyance roller 108 and the paper 92 from the conveyance roller 108. Also, the conveyance roller 108 is rotationally driven by a sub-scanning motor via a gear train.

[0117] The apparatus of this example has a printing receiving member 111 which is a paper guide member. The printing receiving member 111 guides the paper 92 fed out from the conveying roller 108 below the liquid ejection head 1 corresponding to the movement range of the carriage 98 in the main scanning direction.

[0118] On the downstream side of the printing receiving member 111 in the paper conveying direction, a rotatably driven conveying roller 112 and a platen 113 for feeding the paper 92 in the paper discharging direction are provided. Further, a paper discharging roller 114 and a platen 115 for feeding the paper 92 to the paper discharge tray 95, and guide members 116, 117 forming a paper discharge path are arranged.

[0119] When recording with this inkjet recording apparatus 90, the liquid ejection head 1 is driven according to an image signal while moving the carriage 98. For example, ink is ejected onto the stationary paper 92 to record one line, and then after the paper 92 is conveyed by a predetermined amount, the next line is recorded. The recording operation is terminated and the paper 92 is discharged by receiving a recording end signal or a signal that the rear end of the paper 92 has reached the recording area.

[0120] A recovery device 117 for recovering ejection defects of the liquid ejection head 1 is arranged at a position outside the recording area on the right end side in the moving direction of the carriage 98. The recovery device 117 has a capping means, a suction means, and a cleaning means. The carriage 98 is moved to the side of this recovery device 117 during printing standby. Then, the liquid ejection head 1 is capped by the capping means to keep the ejection port portion in a wet state, thereby preventing ejection defects due to ink drying. Also, by ejecting ink not related to recording during recording etc., the ink viscosity of all ejection ports is made constant to maintain a stable ejection state.

[0121] When ejection defects occur or the like, the ejection outlet (nozzle) of the liquid ejection head 1 is sealed by the capping means, and air bubbles and the like are sucked out from the ejection outlet together with the ink by the suction means through the tube. As a result, ink, dust, etc. adhering to the ejection outlet surface are removed by the cleaning means, and the ejection defect is recovered. Further, the sucked ink is discharged to a waste ink reservoir installed at the lower part of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.

[0122] Since this inkjet recording apparatus 90 is equipped with the liquid ejection head 1 of the present embodiment, stable ink ejection characteristics can be obtained and the image quality is improved. In the above, the case where the liquid ejection head 1 is used in the inkjet recording apparatus 90 has been described. However, the liquid ejection head 1 may be applied to a device that ejects droplets other than ink, for example, a liquid resist for patterning.

[0123] Next, another embodiment of the apparatus for ejecting a liquid of the present invention will be described. Hereinafter, a recording apparatus will be described as an example of the apparatus for ejecting a liquid of the present invention. The liquid ejection head of the present invention can be used in various recording apparatuses using an inkjet recording method, for example, printers, facsimile apparatuses, copying apparatuses, printer / fax / duplicators, three-dimensional modeling apparatuses, bioprinters, and the like.

[0124] In the present invention, the recording apparatus and the recording method are an apparatus capable of ejecting ink, various processing liquids, etc. onto a recording medium, and a method of performing recording using the apparatus. The recording medium means something to which ink or various processing liquids can adhere even temporarily.

[0125] This recording apparatus can include not only a head portion for ejecting ink, but also means related to feeding, transporting, and discharging the recording medium, and other apparatuses called a pre-processing apparatus and a post-processing apparatus.

[0126] The recording apparatus and recording method may have heating means used in the heating process and drying means used in the drying process. The heating means and drying means include, for example, means for heating and drying the printing surface or the back surface of the recording medium. The heating means and drying means are not particularly limited, but for example, a hot air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and so on.

[0127] Also, the recording apparatus and recording method are not limited to those in which significant images such as characters and graphics are visualized by ink. For example, those that form patterns such as geometric patterns and those that create three-dimensional images are also included. In addition, the recording apparatus includes, unless otherwise particularly limited, both a serial type apparatus that moves the liquid ejection head and a line type apparatus that does not move the ejection head. Furthermore, this recording apparatus includes not only desktop types but also wide-format recording apparatuses capable of printing on A0-sized recording media, and continuous printers that can use, for example, continuous paper wound in a roll as the recording medium.

[0128] Next, another example of the apparatus for ejecting a liquid according to the present invention will be described with reference to FIGS. 13 and 14. FIG. 13 is a plan explanatory view of the main part of the apparatus, and FIG. 14 is a side explanatory view of the main part of the apparatus.

[0129] This apparatus is a serial type apparatus, and the carriage 403 reciprocates in the main scanning direction by the main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, and the like. The guide member 401 is spanned between the left and right side plates 491A and 491B and holds the carriage 403 movably. Then, by the main scanning motor 405, the carriage 403 is reciprocated in the main scanning direction via the timing belt 408 spanned between the drive pulley 406 and the driven pulley 407.

[0130] This carriage 403 is equipped with a liquid discharge unit 440 that integrates the liquid discharge head 404 and the head tank 441 according to the present invention. The liquid discharge head 404 of the liquid discharge unit 440 discharges liquids of respective colors such as yellow (Y), cyan (C), magenta (M), and black (K), for example. Further, the liquid discharge head 404 is arranged with a nozzle row composed of a plurality of nozzles 16 in a sub-scanning direction orthogonal to the main scanning direction, and is mounted with the discharge direction facing downward.

[0131] A supply mechanism 494 for supplying the liquid stored outside the liquid discharge head 404 to the liquid discharge head 404 supplies the liquid stored in the liquid cartridge 450 to the head tank 441.

[0132] The supply mechanism 494 is composed of a cartridge holder 451 which is a filling part for mounting the liquid cartridge 450, a tube 456, a liquid feeding unit 452 including a liquid feeding pump, and the like. The liquid cartridge 450 is detachably mounted on the cartridge holder 451. The liquid in the liquid cartridge 450 is fed to the head tank 441 by the liquid feeding unit 452 via the tube 456.

[0133] This apparatus includes a conveyance mechanism 495 for conveying the paper 410. The conveyance mechanism 495 includes a conveyance belt 412 which is a conveyance means, and a sub-scanning motor 416 for driving the conveyance belt 412.

[0134] The conveyance belt 412 adsorbs the paper 410 and conveys it to a position facing the liquid discharge head 404. This conveyance belt 412 is an endless belt and is stretched between a conveyance roller 413 and a tension roller 414. The adsorption can be performed by electrostatic adsorption, air suction, or the like.

[0135] Then, the conveyance belt 412 moves in a circular motion in the sub-scanning direction when the conveyance roller 413 is rotationally driven by the sub-scanning motor 416 via a timing belt 417 and a timing pulley 418.

[0136] Furthermore, on one side of the carriage 403 in the main scanning direction, a maintenance and recovery mechanism 420 for maintaining and recovering the liquid ejection head 404 is arranged on the side of the conveyance belt 412.

[0137] The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzles 16 are formed) of the liquid ejection head 404, a wiper member 422 that wipes the nozzle surface, and the like.

[0138] The main scanning movement mechanism 493, the supply mechanism 494, the maintenance and recovery mechanism 420, and the conveyance mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0139] In this apparatus configured as described above, the sheet 410 is fed onto the conveyance belt 412 and adsorbed, and the sheet 410 is conveyed in the sub-scanning direction by the circumferential movement of the conveyance belt 412.

[0140] Therefore, while moving the carriage 403 in the main scanning direction, the liquid ejection head 404 is driven according to the image signal, so that liquid is ejected onto the stationary sheet 410 to form an image.

[0141] Thus, in this apparatus, since it is equipped with the liquid ejection head according to the present invention, a high-quality image can be stably formed.

[0142] Next, another example of the liquid ejection unit according to the present invention will be described with reference to FIG. 15. FIG. 15 is an explanatory plan view of the main part of the unit.

[0143] This liquid ejection unit is composed of a housing portion formed by side plates 491A, 491B, and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid ejection head 404 among the members constituting the apparatus that ejects the liquid.

[0144] Note that it is also possible to configure a liquid discharge unit in which at least one of the above-described maintenance and recovery mechanism 420 and supply mechanism 494 is further attached to, for example, the side plate 491B of this liquid discharge unit.

[0145] Next, another example of the liquid discharge unit according to the present invention will be described with reference to FIG. 16. FIG. 16 is a front explanatory view of the unit.

[0146] This liquid discharge unit is composed of a liquid discharge head 404 to which a flow path component 444 is attached and a tube 456 connected to the flow path component 444.

[0147] Note that the flow path component 444 is disposed inside the cover 442. Instead of the flow path component 444, a head tank 441 can also be included. Further, a connector 443 for making an electrical connection with the liquid discharge head 404 is provided above the flow path component 444.

[0148] In the present application, the "device for discharging liquid" is a device that includes a liquid discharge head or a liquid discharge unit and drives the liquid discharge head to discharge liquid. The device for discharging liquid includes not only a device capable of discharging liquid onto an object to which the liquid can adhere, but also a device capable of discharging liquid into the air or liquid.

[0149] This "device for discharging liquid" can also include means related to the feeding, conveying, and paper discharging of an object to which the liquid can adhere, as well as other pretreatment devices, post-treatment devices, and the like.

[0150] For example, as the "device for discharging liquid", there are an image forming device that discharges ink to form an image on paper, and a three-dimensional modeling device (three-dimensional modeling device) that discharges a modeling liquid onto a powder layer formed by laminating powders in order to model a three-dimensional object (three-dimensional object).

[0151] Further, the "device for discharging liquid" forms a significant image such as characters and figures by the discharged liquid It is not limited to what can be visualized. For example, it includes those that form patterns that have no meaning by themselves, those that create three-dimensional images, etc.

[0152] The above "thing to which liquid can adhere" means a thing to which liquid can adhere at least temporarily, such as a thing to which liquid adheres and adheres firmly, a thing to which liquid adheres and penetrates, etc. Specific examples include recording media such as paper, recording paper, recording sheet, film, cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as inspection cells, etc. As long as it is not particularly limited, all things to which liquid adheres are included.

[0153] The material of the above "thing to which liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, building materials such as wallpaper and floor materials, textile for clothing, etc., as long as liquid can adhere even temporarily.

[0154] Also, "liquid" includes ink, processing liquid, DNA sample, resist, pattern material, binder, shaping liquid, or solutions and dispersions containing amino acids, proteins, calcium, etc.

[0155] Also, as for the "device for discharging liquid", there is a device in which a liquid discharge head and a thing to which liquid can adhere move relatively, but it is not limited to this. Specific examples include a serial type device that moves the liquid discharge head, a line type device that does not move the liquid discharge head, etc.

[0156] Also, other "devices for discharging liquid" include a processing liquid coating device that discharges a processing liquid onto paper for the purpose of modifying the surface of the paper, an injection granulation device that injects a composition liquid in which raw materials are dispersed in a solution through a nozzle to granulate fine particles of the raw materials, etc.

[0157] The "liquid ejection unit" is an integrated unit of a liquid ejection head, functional components, and mechanisms, and is an assembly of components related to liquid ejection. For example, the "liquid ejection unit" includes at least one of the configurations of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism combined with the liquid ejection head, etc.

[0158] Here, the integration means, for example, that the liquid ejection head, functional components, and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., and those in which one is movably held with respect to the other are included. Also, the liquid ejection head and the functional components and mechanisms may be configured to be detachable from each other.

[0159] For example, as a liquid ejection unit, there is one in which a liquid ejection head and a head tank are integrated, such as the liquid ejection unit 440 shown in FIG. 14. Also, there are those in which a liquid ejection head and a head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter can also be added between the head tank and the liquid ejection head of these liquid ejection units.

[0160] Also, as a liquid ejection unit, there is one in which a liquid ejection head and a carriage are integrated.

[0161] Also, as a liquid ejection unit, there is one in which a liquid ejection head is movably held by a guide member that constitutes a part of a scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated. Also, as shown in FIG. 15, as a liquid ejection unit, there is one in which a liquid ejection head, a carriage, and a main scanning movement mechanism are integrated.

[0162] Also, as a liquid ejection unit, there is one in which a cap member, which is a part of a maintenance and recovery mechanism, is fixed to a carriage to which a liquid ejection head is attached, and the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated.

[0163] In addition, as shown in FIG. 16, there is a liquid discharge unit in which a tube is connected to a liquid discharge head to which a head tank or a flow path component is attached, and the liquid discharge head and the supply mechanism are integrated.

[0164] The main scanning movement mechanism shall include the guide member alone. In addition, the supply mechanism shall include the tube alone and the loading unit alone.

[0165] In addition, the "liquid discharge head" is not limited to the pressure generating means used. For example, in addition to the piezoelectric actuator (which may use a laminated piezoelectric element) as described in the above embodiment, a thermal actuator using an electrothermal conversion element such as a heating resistor, an electrostatic actuator composed of a diaphragm and a counter electrode, etc. may also be used.

[0166] In addition, in the terms of the present application, image formation, recording, printing, imprinting, printing, shaping, etc. are all synonymous.

Explanation of Reference Numerals

[0167] 10 Lower electrode 11 Upper electrode 12 Piezoelectric element 13 Diaphragm 14 Partition wall 15 Individual liquid chamber 15a End of individual liquid chamber 15b Connection part 15-1, 15-2 Short sides of individual liquid chamber 15-3, 15-4 Long sides of individual liquid chamber 16 Nozzle 18 Common liquid chamber 19 Common liquid supply path 20 Piezoelectric body 20a End of piezoelectric body 42 Wiring 45 Interlayer insulating film 48 Joint part 49 Adhesive 68 Flow path 100 Actuator substrate 200 Support substrate 300 Nozzle Substrate

Prior Art Documents

Patent Documents

[0168]

Patent Document 1

Patent Document 2

Claims

1. A liquid chamber substrate, a diaphragm formed on the liquid chamber substrate, a lower electrode formed on the diaphragm, a piezoelectric body formed on the lower electrode, an upper electrode formed on the piezoelectric body, wiring for driving the piezoelectric body, a liquid ejection head having a nozzle substrate having a nozzle, wherein the liquid chamber substrate has individual liquid chambers formed at positions facing the piezoelectric body with the diaphragm interposed therebetween, the individual liquid chambers and the piezoelectric body are polygons having four or more sides in plan view, the wiring is formed on a part of the individual liquid chamber and is at least formed on the midpoint of one of the plurality of sides of the individual liquid chamber in plan view, and with this midpoint as a reference point, when the distance from the reference point in plan view to the midpoint of the other side of the individual liquid chamber is defined as distance L, the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the largest is defined as A, and the distance between the end of the individual liquid chamber and the end of the piezoelectric body on the side where distance L is the smallest is defined as B, A < B A liquid ejection head characterized by satisfying the above. However, when there are a plurality of sides where distance L is the largest, the above formula is satisfied for all corresponding sides, and when there are a plurality of sides where distance L is the smallest, the above formula is satisfied for all corresponding sides.

2. The liquid ejection head according to claim 1, wherein in plan view, the corners of the individual liquid chambers and the piezoelectric body have a curved shape.

3. Regarding one of the corners of the individual liquid chambers, when the average value of the distance between the end of the piezoelectric body and the end of the individual liquid chamber in the portion having a curved shape is defined as C, when there is a corner where the side having A and the side having B are connected, that corner satisfies A < C < B and when there is no corner where the side having A and the side having B are connected, all of the corners of the individual liquid chambers excluding the corner having the side having the reference point as one side satisfy A < C < B The liquid ejection head according to claim 2, characterized by satisfying the above.

4. The liquid ejection head according to any one of claims 1 to 3, wherein a connection portion with a flow path communicating with a common liquid chamber is formed at the central portion of the side of the individual liquid chamber facing the side having the reference point or at the corner where two sides of the sides of the individual liquid chamber facing the side having the reference point are connected.

5. The liquid ejection head according to any one of claims 1 to 4, wherein the individual liquid chamber is rectangular in plan view.

6. A liquid discharge unit comprising the liquid discharge head according to any one of claims 1 to 5.

7. The liquid discharge unit according to claim 6, characterized in that at least one of a head tank for storing the liquid supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying the liquid to the liquid discharge head, a maintenance and recovery mechanism for performing maintenance and recovery of the liquid discharge head, and a main scanning movement mechanism for moving the liquid discharge head in the main scanning direction is integrated with the liquid discharge head.

8. An apparatus for discharging a liquid, comprising the liquid discharge head according to any one of claims 1 to 5, or the liquid discharge unit according to claim 6 or 7.

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