Liquid ejection head and manufacturing method thereof

Abstract

To improve the moldability of a member in which pitch conversion channels are formed.SOLUTION: An array of pitch conversion channels P1 to Pn (n being an integer equal to 3 or greater) has a repeated pattern in which a set that minimizes a number of pitch conversion channels under a condition of including one or more respective of the pitch conversion channels P1 to Pn, is repeatedly arranged. A number of pitch conversion channels included in a set is greater than n, and at least one of two pitch conversion channels adjacent to an m-th pitch conversion channel (m being all integers 1 to n-2) is any of the first to (m+1)th pitch conversion channels.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a manufacturing method thereof. [Background technology]

[0002] In liquid ejection devices, a page-wide type liquid ejection head in which ejection ports are arranged across the entire width of the recording medium is sometimes used to increase the printing speed. In such liquid ejection heads, a pitch conversion flow path is sometimes used to supply liquid to an element substrate having multiple rows of ejection ports. Liquid is supplied from a common flow path extending in the direction in which the ejection ports are arranged to a common liquid chamber of each element substrate via a pitch conversion flow path. The member that forms the pitch conversion flow path is often a molded part such as a resin. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4495762 Summary of the Invention [Problem to be solved by the invention]

[0004] It is required to arrange pitch-conversion channels at a high density in order to realize high density of ejection ports for cost reduction, high printing speed, and an increase in supply ports for handling high viscosity liquids. In order to reliably join a member in which pitch-conversion channels are arranged at a high density to another member, a high degree of flatness is required for the joining surface of the pitch-conversion channel. However, when a member in which a pitch-conversion channel is formed is formed by molding a resin or the like, the complex configuration of the pitch-conversion channel may hinder the flow of resin, making it easy for sink marks to occur. This may deteriorate the flatness of the member and reduce the joining reliability of the member.

[0005] An object of the present invention is to provide a liquid ejection head in which the moldability of a member in which a pitch conversion flow passage is formed is improved. [Means for solving the problem]

[0006] The liquid ejection head of the present invention has a plurality of ejection ports for ejecting liquid, first to nth common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which liquid flows, and connected to the corresponding ejection ports, first to nth common flow channels arranged in parallel in the order of first to nth, through which liquid flows, and first to nth pitch change flow channels that connect the first to nth common flow channels and the first to nth common liquid chambers, respectively, and have a periphery made of resin. The first to nth common liquid chambers are located on the side of the first common flow channel. The arrangement of the first to nth pitch change flow channels has a repeating pattern in which a set that includes at least one of the first to nth pitch change flow channels and has the smallest number of pitch change flow channels is repeatedly arranged. The number of pitch change flow channels included in one set is greater than n, and at least one of two pitch change flow channels adjacent to the mth pitch change flow channel (m is any integer from 1 to n-2) is any one of the first to (m+1)th pitch change flow channels. In the first aspect, n or more pitch change channels other than the nth pitch change channel are arranged between adjacent nth pitch change channels, and the pitch change channels other than the nth pitch change channel are composed of only one section in which the length of the pitch change channel increases monotonically and one section in which the length of the pitch change channel decreases monotonically. In the second aspect, when the numbers of the 1st to nth pitch change channels included in the set are Q1, Q2, ..., Qn, Q1>Qn and Q1≧Q2≧...≧Qn are satisfied. In the third aspect, the pitch change section including the pitch change channel, a common channel section including the 1st to nth common channels, and a missing section of the pitch change section that overlaps with the common channel section but does not overlap with the pitch change section when viewed in the height direction of the pitch change channel are further included. In the fourth aspect, the 1st to nth pitch change channels and communication holes connecting the 1st to nth pitch change channels and the 1st to nth common channels are formed of an integral member. In the fifth aspect, the first to n-th pitch conversion channels and the substrate connecting channels connecting the first to n-th pitch conversion channels and the first to n-th common liquid chambers are formed from an integral member. Effect of the Invention

[0007] According to the present invention, it is possible to provide a liquid ejection head in which the moldability of the member in which the pitch conversion flow passage is formed is improved. [Brief description of the drawings]

[0008] [Figure 1] 1 is a perspective view of a liquid ejection head according to a first embodiment of the present invention. [Diagram 2] 2 is a schematic diagram of an element substrate of the liquid ejection head according to the first embodiment. [Diagram 3] FIG. 2 is an exploded perspective view of an element substrate and a liquid channel unit. [Figure 4] 5A and 5B are diagrams showing the arrangement of openings in members that configure the liquid passage unit. [Diagram 5] FIG. 4 is a diagram showing the arrangement of pitch-changing channels in the first embodiment and a comparative example. [Figure 6] FIG. 13 is a diagram showing variations (n=3) of the pitch-conversion flow passage arrangement. [Figure 7] FIG. 13 is a diagram showing variations (n=4) of the pitch-conversion flow passage arrangement. [Figure 8] FIG. 13 is a diagram showing variations (n=5) of the pitch-conversion flow passage arrangement. [Figure 9] FIG. 11 is a schematic diagram of a liquid channel unit according to a second embodiment of the present invention. [Figure 10] FIG. 11 is a schematic diagram of a liquid channel unit according to a second embodiment of the present invention. [Figure 11] 13 is a schematic diagram of a liquid channel unit according to another modified example. FIG. [Figure 12] 13 is a schematic diagram of a liquid channel unit according to another modified example. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, some embodiments of the present invention will be described with reference to the drawings. The embodiments described below do not limit the scope of the present invention. In the liquid ejection head of this embodiment, a thermal method is adopted in which ink is ejected by generating bubbles using a heat generating resistor element. However, the present invention can also be applied to liquid ejection heads that adopt a piezo method and various other liquid ejection methods as long as the ink can be given energy for ejection. In this embodiment, the liquid is ink, but the liquid is not limited to ink. The liquid ejection head of this embodiment has an integrated configuration in which ejection ports are arranged across the entire width of the recording medium, but may have a configuration in which multiple liquid ejection heads are arranged according to the width of the recording medium.

[0010] In the following description, the width direction of the recording medium is called the X direction, and the transport direction of the recording medium is called the Y direction. The X direction and the Y direction are perpendicular to each other. The direction perpendicular to the X direction and the Y direction is called the Z direction. The Z direction coincides with the height direction of the pitch conversion flow path. The present invention is preferably applicable to a line type liquid ejection head, but can also be applied to a liquid ejection head mounted on a carriage that moves in the width direction of the recording medium. In that case, the X direction may coincide with the transport direction of the recording medium, and the Y direction may coincide with the width direction of the recording medium.

[0011] In each embodiment, the liquid ejection head ejects four types of ink (for example, C (cyan), M (magenta), Y (yellow), and K (black)). The liquid chambers, flow paths, etc. through which the ink flows are divided into those for ink supply and those for ink recovery. Therefore, in the following description, suffixes a to h may be added to distinguish the type of ink and the ink for supply and recovery. The number of ink colors is not limited to four, and n types or colors of ink (n is an integer of 3 or more) can be used. Therefore, in general, the common liquid chamber, common flow path, and pitch conversion flow path have two for each color, one for supply and one for recovery, and therefore can be called 1st to 2n common liquid chambers, 1st to 2n common flow paths, and 1st to 2n pitch conversion flow paths. The liquid chambers, flow paths, etc. for ink supply and the liquid chambers, flow paths, etc. for ink recovery may be reversed. In the liquid ejection device of this embodiment, the ink is circulated between the liquid supply unit and the liquid ejection head, but the ink does not have to be circulated. In this case, the ink recovery liquid chamber, flow path, etc. may be omitted. When there is no need to distinguish between the type of ink and whether it is for supply or recovery, the subscripts a to h may be omitted.

[0012] (First embodiment) 1(a) and 1(b) are perspective views of a liquid ejection head 1 according to a first embodiment of the present invention, as viewed from the ejection port side and the opposite side, respectively. The liquid ejection head 1 includes a plurality of element substrates 2, a liquid flow path unit 3, a housing 4, a plurality of electric wiring boards 5, and an electric connection board 6. The plurality of element substrates 2 and the plurality of electric wiring boards 5 are arranged across the entire width W of a recording medium having the maximum recordable width. The plurality of electric wiring boards 5 are connected to the corresponding element substrates 2. Ink is supplied from a liquid supply unit (not shown) connected to the liquid flow path unit 3 to the element substrate 2 through the liquid flow path unit 3, and is collected by the liquid supply unit again through the liquid flow path unit 3. An energy generating element 25 (see FIG. 2) is arranged on the element substrate 2. By driving the energy generating element 25 through the electric connection board 6 and the electric wiring board 5, ink is ejected from the corresponding ejection port.

[0013] FIG. 2(a) is a plan view of the element substrate 2 as viewed from the ejection port formation surface side, and FIG. 2(b) is a plan view of the element substrate 2 as viewed from the connection surface side with the liquid flow path unit 3 (i.e., the back side of the ejection port formation surface). FIG. 2(c) is a schematic cross-sectional view showing the flow paths in the element substrate 2 along the AA section of FIG. 2(b). The element substrate 2 has an outer shape of a parallelogram with four acute or obtuse angled corners. The element substrate 2 is provided with a plurality of ejection ports 26 corresponding to the inks of each color and ejecting the inks of each color. The ejection ports 26 are formed into rows (ejection port rows) 21a to 21d for each color of ink to be ejected. Therefore, the element substrate 2 is provided with four ejection port rows 21a to 21d for ejecting four types of ink, and rows of energy generating elements 25 corresponding thereto. The ejection port rows 21a to 21d are arranged at a slight incline with respect to the X direction, but may be parallel to the X direction. The ejection opening arrays that eject ink of the same color are arranged across a plurality of element substrates 2 and are continuously arranged across the entire width W of the recording medium.

[0014] The supply path and recovery path of ink will be described with reference to Figs. 2 to 5(a). Fig. 3(a) is an exploded perspective view showing the liquid flow path unit 3 and the element substrate 2. Fig. 3(b) is a schematic cross-sectional view of the liquid flow path unit 3 and the element substrate 2. Fig. 4 is a diagram showing the arrangement of openings of members constituting the liquid flow path unit 3. Figs. 4(a) and 4(b) respectively show the front and back surfaces of the substrate connection member 9, Figs. 4(c) and 4(e) respectively show the front and back surfaces of the pitch conversion member 8, and Figs. 4(f) and 4(g) respectively show the opening arrangements of the front and back surfaces of the common flow path member 7. Note that, when the element substrate 2 side of each member is the front, Fig. 4(d) is a cross-sectional view of the pitch conversion member 8 taken along line BB in Fig. 3(b). Fig. 5(a) is a schematic view showing the arrangement of the common flow paths 31a to 31h and the pitch conversion flow paths 32a to 32h. The liquid flow path unit 3 is composed of three members: the common flow path member 7, the pitch conversion member 8, and the substrate connection member 9. The pitch conversion member 8 constitutes a pitch conversion section 132 (see FIG. 3(b)) including the first to fourth pitch conversion flow paths 32a to 32h. The common flow path member 7 and the pitch conversion member 8 constitute a common flow path section 131 (see FIG. 3(b)) including the first to fourth common flow paths 31a to 31h. The common flow path member 7, the pitch conversion member 8 and the substrate connection member 9 are formed by injection molding of resin. Therefore, the manufacturing method of the liquid ejection head 1 includes a step of forming the periphery of the first to fourth pitch conversion flow paths 32a to 32h from resin. Of the liquid flow path unit 3, a portion other than the periphery of the pitch conversion flow path 32 may be formed from a material other than resin.

[0015] As shown in FIG. 2(c), inside the element substrate 2, two common liquid chambers 22 through which the ink flows are provided for each ink. Eight common liquid chambers 22a-22h are arranged in parallel, more specifically, parallel to each other. The common liquid chambers 22 are connected to the corresponding ejection ports 26 via the individual liquid chambers 24. As shown in FIG. 2(b), the bonding surface of the element substrate 2 to the liquid flow path unit 3 is provided with first to fourth openings 23a-23h. The openings 23 communicate with the common liquid chambers 22 and a common flow path 31 described later. One or more openings 23a-23h are provided for each. The ink supplied from the common flow path 31 flows into the individual liquid chambers 24 through the openings 23a-23d and the common liquid chambers 22a-22d. The ink further passes through the common liquid chambers 22e-22h and the openings 23e-23h, and is collected in the common flow paths 31e-31h. The individual liquid chambers 24 are provided corresponding to the respective ejection ports 26 and the respective energy generating elements 25 .

[0016] As shown in FIG. 3(b) and FIG. 5(a), the liquid flow path unit 3 has first to fourth common flow paths 31a to 31h through which ink flows. The common flow paths 31a to 31d for ink supply are arranged in parallel in the order of first to fourth, and the common flow paths 31e to 31h for ink recovery are also arranged in parallel in the order of first to fourth. More specifically, the eight common flow paths 31a to 31h are arranged in parallel to each other. The common flow paths 31a to 31d for ink supply are provided in one half of the liquid flow path unit 3 in the Y direction, and the common flow paths 31e to 31h for ink recovery are provided in the other half of the liquid flow path unit 3 in the Y direction. The common flow paths 31a to 31h are arranged such that the fourth common flow paths 31a, 31h are located at the end side of the liquid flow path unit 3 in the Y direction, and the first common flow paths 31d, 31e are located at the center side of the liquid flow path unit 3 in the Y direction. The element substrate 2 is provided at the center of the liquid flow path unit 3 in the Y direction, and the common liquid chamber 22 is located on the side of the first common flow paths 31d and 31e.

[0017] The common flow path member 7 is provided with first to fourth lower groove portions 72a to 72h which become part of the common flow paths 31a to 31h, and first to fourth joint portions 71a to 71h which connect a liquid supply unit (not shown) to the first lower groove portions 72a to 72h.

[0018] The pitch conversion member 8 is provided with first to fourth upper grooves 81a to 81h which are part of the common flow paths 31a to 31h. The upper grooves 81a to 81h are provided at positions facing the first lower grooves 72a to 72h. The common flow paths 31a to 31h are formed by joining the common flow path member 7 and the pitch conversion member 8 so that the first lower grooves 72a to 72h and the upper grooves 81a to 81h communicate with each other. The pitch conversion member 8 is provided with first to fourth pitch conversion flow path grooves 83a to 83h which form the first to fourth pitch conversion flow paths 32a to 32h. As shown in FIGS. 3 and 5(a), the element substrate 2 is very narrower than the liquid flow path unit 3, so that the arrangement pitch in the Y direction of the common liquid chambers 22a to 22h is smaller than the arrangement pitch in the Y direction of the common flow paths 31a to 31h. The pitch conversion flow channels 32a-32h are provided to convert the arrangement pitch in the Y direction of the common flow channels 31a-31h to the arrangement pitch in the Y direction of the common liquid chambers 22a-22h. The pitch conversion flow channels 32a-32h extend in the Y direction, but may extend at an angle relative to the Y direction. Furthermore, the pitch conversion member 8 is provided with first to fourth communication holes 82a-82h that communicate between the first to fourth pitch conversion flow channel grooves 83a-83h and the first to fourth upper groove portions 81a-81h.

[0019] The substrate connecting member 9 is provided with first to fourth substrate connecting flow paths 91a to 91h at positions facing the first to fourth openings 23a to 23h of the element substrate 2. The ends of the pitch conversion flow path grooves 83a to 83h opposite the communication holes 82a to 82h face the substrate connecting flow paths 91a to 91h. By joining the pitch conversion member 8 and the substrate connecting member 9, pitch conversion flow paths 32a to 32h communicating with the substrate connecting flow paths 91a to 91h are formed. With the above configuration, a liquid supply path is formed for supplying ink from the liquid flow path unit 3 to the element substrate 2 and recovering ink from the element substrate 2 to the liquid flow path unit 3.

[0020] Next, the arrangement of the pitch conversion channels 32a-32h will be described with reference to FIG. 5. In the following description, the first to fourth pitch conversion channels 32a-32d are referred to as pitch conversion channels P1-P4. Although the description is omitted, the first to fourth pitch conversion channels 32e-32h are also configured similarly to the first to fourth pitch conversion channels 32a-32d. FIG. 5(b) is a schematic diagram showing the arrangement of the common channels 31a-31h and the pitch conversion channels P1-P4 of a comparative example. In the embodiment shown in FIG. 5(a) and the comparative example shown in FIG. 5(b), the common channels 31a-31h have the same configuration, but the pitch conversion channels P1-P4 have different configurations. The pitch conversion channels P1-P4 are arranged along the extension direction (X direction) of the common channel 3. The pitch conversion channels P1-P4 connect the common channels 31a-31d and the common liquid chambers 22a-22d. The number of each pitch conversion flow channel P1-P4 is not limited, but in this embodiment, a plurality of each pitch conversion flow channel P1-P4 is provided. The ratio of the arrangement pitch of the pitch conversion flow channels P1-P4 in the X direction to the arrangement pitch of the common flow channels 31a-31h in the Y direction is preferably in the range of 1 / 3 to 3. If the arrangement pitch of the pitch conversion flow channels P1-P4 in the X direction is too small, the filling property of the resin decreases, and if the arrangement pitch is too large, the ink flow channel length increases, leading to an increase in pressure loss.

[0021] In the following description, the number of common channels 31 arranged in either the +Y direction (direction of the arrow) or the -Y direction (opposite direction of the arrow) with respect to the element substrate 2 (the +Y direction in the description of FIG. 5) is n (n is an integer of 3 or more). In addition, the pitch conversion channels 32 connected to the common channels 31 are P1, P2, . . . , Pn in order from the one closest to the element substrate 2. The arrangement of the pitch conversion channels has a repeating pattern in which a "set" with the minimum number of pitch conversion channels is repeatedly arranged under the condition that each of the pitch conversion channels P1 to Pn is included in one or more. This minimum number is the repeating period C of the arrangement of the pitch conversion channels. In the example shown in FIG. 5(a), C=8 and n=4, and in the example shown in FIG. 5(b), C=4 and n=4. The pitch conversion channels are arranged in one period per element substrate 2, but one element substrate 2 may include multiple periods.

[0022] The arrangement of the pitch-changing flow paths P1 to Pn satisfies at least some of the following conditions 1 to 5. These conditions will be described in detail below. Among these, conditions 1 and 2 are essential conditions for this embodiment, and conditions 3 to 5 are conditions that further enhance the effects of this embodiment. The arrangement of the pitch-changing flow paths P1 to Pn is not limited to the examples shown below as long as conditions 1 and 2 are satisfied. Before describing conditions 1 to 5, Figs. 6 to 8 will be described. Figs. 6 to 8 summarize variations in the arrangement of the pitch-changing flow paths and the suitability of conditions 1 to 5. Cases 3-1 to 3-6 in Fig. 6 are examples of arrangements when n=3, cases 4-1 to 4-6 in Fig. 7 are examples of arrangements when n=4, and cases 5-1 to 5-4 in Fig. 8 are examples of arrangements when n=5. In each figure, the cases surrounded by thick lines are examples, and the rest are comparative examples.

[0023] Condition 1: The number of pitch changing flow paths P1 to Pn included in one group is greater than n. That is, C>n holds in at least a part of the region of the arrangement of the pitch-changing flow passages. In the embodiment shown in Fig. 5(a), the pitch-changing flow passages are arranged in the order of P1→P2→P3→P4→P3→P4→P1→P2 in the -X direction, so n=4, C=8, and C>n holds. In contrast, in the comparative example shown in Fig. 5(b), the pitch-changing flow passages are arranged in the order of P1→P3→P2→P4→P1→P3→P2→P4 in the -X direction, so n=4, C=4, and C>n does not hold.

[0024] ·Condition 2 For any pitch change flow channel Pm (m is any integer from 1 to n-2), at least one of the two pitch change flow channels adjacent to the m-th pitch change flow channel Pm is any of the first to (m+1)-th pitch change flow channels P1 to Pm+1. This condition means that when a pitch conversion flow path is Px and a pitch conversion flow path adjacent to the pitch conversion flow path Px on either side is Py, the common flow path 31 to which Py is connected is not located two or more steps outside the common flow path 31 to which Px is connected in the Y direction. In other words, it means that the length of at least one of the Py on both sides is not two or more steps longer than the length of Px. In other words, it means that the case where "the lengths of two Py adjacent to Px on both sides are both two or more steps longer than Px" is excluded. m is an integer from 1 to n-2. The reason why m=n-1 is excluded is because the pitch conversion flow path Pn-1 always satisfies the condition P1 to P(m+1) regardless of which pitch conversion flow path P1 to Pn it is adjacent to, and the reason why m=n is excluded is the same. In the embodiment shown in FIG. 5(a), this condition is satisfied. In contrast, in the comparative example shown in FIG. 5(b), since there is a pitch conversion flow path P1 with pitch conversion flow paths P3 and P4 arranged on both sides, this condition is not satisfied.

[0025] The effects of conditions 1 and 2 will be described. In Fig. 5(a) and 5(b), the flow of resin at the Y-direction end of the pitch conversion member 8 is indicated by arrows. In the comparative example shown in Fig. 5(b), the resin outside the pitch conversion flow path P4 flows linearly around the outer periphery, whereas the resin that has entered the inner side of the pitch conversion flow path P4 repeats complex branching and merging at a fine cycle. Furthermore, since the pitch conversion flow path P1 is sandwiched between the pitch conversion flow paths P3 and P4, a resin flow that penetrates deeply from the outer side toward the pitch conversion flow path P1 with a narrow width occurs in this portion. In this way, when the repeating cycle is short (condition 1 is not satisfied) or when a pitch conversion flow path is sandwiched between pitch conversion flow paths that are significantly longer than the length of the pitch conversion flow path (condition 2 is not satisfied), the flow direction of the resin changes at a fine cycle, and the resin branches and merges more frequently. As a result, the resin is filled in a narrow area at a steep angle to the flow at the outer periphery. This increases the pressure loss when filling the resin, which may result in insufficient pressure being applied at points far from the gate, resulting in large sink marks. For example, as shown in FIG. 5(c), when the gate G is provided in the center of the pitch conversion member 8 in the longitudinal direction, both ends in the longitudinal direction become the final filling region R. In the pitch conversion flow path arrangement of the comparative example, the pressure loss is large until the resin reaches the final filling region R from the gate G, and sufficient pressure cannot be applied in the vicinity of the final filling region R. As a result, sink marks S as shown in FIG. 5(d) may occur. The sink marks S are depressions in the surface of the pitch conversion member 8, which is also the bonding surface with the substrate connecting member 9. Therefore, the flatness of the bonding surface of the pitch conversion member 8 may deteriorate, and poor bonding between the pitch conversion member 8 and the substrate connecting member 9 may occur.

[0026] In contrast, in the pitch-conversion flow channel array of this embodiment shown in Fig. 5(a), the repeat period C of the array of pitch-conversion flow channels P1-P4 is set to 8, which is larger than n (=4), thereby reducing the number of branching and merging points of the resin. Furthermore, none of the pitch-conversion flow channels P1-P4 is sandwiched between pitch-conversion flow channels that are two or more stages longer than the length of the channel. This makes the angles of branching and merging of the resin gentler, improving the filling of the resin.

[0027] 6 to 8, as shown in cases 3-1, 4-1, and 5-1 (all comparative examples), in an arrangement where C=n, the resin flow fluctuates at short intervals, and pressure loss is likely to increase. Also, as shown in cases 3-2, 4-2, and 5-2 (all comparative examples), if there is a pitch-conversion flow path that is sandwiched between pitch-conversion flow paths that are two or more stages longer on both sides, the resin flow in that area changes suddenly, making filling difficult. In contrast, cases 3-3 to 3-6, 4-3 to 4-6, and 5-3 to 5-4 satisfy conditions 1 and 2, and thus it is possible to realize resin flow in open areas and improve filling performance.

[0028] Condition 3: n or more pitch change channels other than the n-th pitch change channel are disposed between adjacent n-th pitch change channels. That is, if the arrangement interval of the longest pitch-change flow passage Pn is Cn, there is a region where Cn>n. The arrangement interval Cn means that there are (Cn-1) pitch-change flow passages other than Pn between adjacent pitch-change flow passages Pn. In FIG. 5(a), there is a region (Cn=6) where a total of five pitch-change flow passages P1, P2, P3 are sandwiched between adjacent pitch-change flow passages P4. Cases 3-4 to 3-6, 4-4 to 4-6, and 5-3 to 5-4 also satisfy this condition. By satisfying condition 3, the change in the flow of the resin becomes more gradual, and the filling property is improved. In this case, as shown in Cases 3-4 and 4-4, by alternately arranging the parts where P1 to Pn are arranged in descending order and the parts where they are arranged in ascending order, the flow of the resin becomes smoother. In other words, the pitch-change flow passages other than the nth pitch-change flow passage sandwiched between the nth pitch-change flow passages consist of only one section where the length of the pitch-change flow passage monotonically increases and one section where the length of the pitch-change flow passage monotonically decreases. In Fig. 5(a), there is a section where another pitch-change flow passage is sandwiched between the pitch-change flow passages P4, but this pitch-change flow passage is P3, so condition 2 is satisfied. Therefore, the fluctuation of the resin flow is kept small.

[0029] Condition 4: At least one of the pitch change channels adjacent to the n-th pitch change channel is another n-th pitch change channel or the (n-1)th pitch change channel. In FIG. 5(a), one of the pitch-conversion channels adjacent to the pitch-conversion channel P4 is the pitch-conversion channel P3. Note that "adjacent" means that there is no pitch-conversion channel between them, and "adjacent" means that another type of pitch-conversion channel is present between them. Cases 3-3 to 3-6, 4-3 to 4-6, and 5-4 also satisfy this condition. By satisfying condition 4, the change in resin flow becomes more gradual, improving the filling performance. In case 5-3, the longest pitch-conversion channel P5 protrudes from the adjacent pitch-conversion channels P3 on both sides, but in case 5-4, condition 4 is satisfied, so the protruding length of the longest pitch-conversion channel P5 is reduced, making it possible to achieve a smoother resin flow.

[0030] · Condition 5: When the numbers of 1st to nth pitch-changing flow passages included in one group are Q1, Q2, . . . , Qn, Q1>Qn and Q1≧Q2≧ . . . ≧Qn are satisfied. That is, at least one of the first to nth pitch conversion channels is different in number from the other first to nth pitch conversion channels, and the number of long pitch conversion channels is not greater than the number of shorter pitch conversion channels. This condition means that the number of short pitch conversion channels is relatively large compared to the number of long pitch conversion channels. In case 3-6, there are three pitch conversion channels P1, P2 and two pitch conversion channels P3. In case 4-6, there are three pitch conversion channels P1, P2 and two pitch conversion channels P3, P4. This condition is applicable, for example, to a case where the number of pitch conversion channels is made different on the supply side and the recovery side depending on the ink circulation conditions, or the number of pitch conversion channels is made different depending on the type of ink for each ejection port array 21 or the printing duty used. Since the number of shorter pitch conversion channels is increased, the flow of resin entering the interior at a steep angle from the outer periphery is suppressed, and the effect of the present invention is enhanced.

[0031] Furthermore, pitch conversion channels of the same type (length) may be arranged adjacent to each other. This makes the change in resin flow more gradual, improving the filling property. For example, in cases 3-3, 3-4 and 4-4, the pitch conversion channels P1 are arranged adjacent to each other. When these pitch conversion channels P1 are connected to one element substrate 2, the openings 23 connected to the common liquid chamber 22 are arranged close to each other, and as a result, the flow distance of the ink in the common liquid chamber 22 becomes long, and there is a possibility that the pressure loss becomes large. Depending on the usage form of the liquid ejection head 1, it is necessary to suppress the pressure loss to a small value. In that case, it is also possible to arrange the pitch conversion channels of the same type so that they are not adjacent to each other in one element substrate 2, as in cases 3-5 and 4-5. These arrangements can be appropriately selected in consideration of the usage form.

[0032] As described above, according to this embodiment, it is possible to smoothly fill the resin. This makes it possible to transmit pressure sufficiently even at points far from the gate. As a result, even when the pitch conversion flow path is highly densified, sink marks are suppressed, and it is possible to provide a liquid ejection head 1 with high bonding reliability.

[0033] Second Embodiment A second embodiment will be described with reference to FIG. 9. The overall configuration of the liquid ejection head 1 and the arrangement of the pitch conversion flow passage in the second embodiment are omitted since they are the same as those in the first embodiment. FIG. 9(a) is a plan view of a part of the pitch conversion member 8 seen from the substrate connection member 9 side, and FIG. 9(b) is a schematic cross-sectional view along the CC section of FIG. 9(a). In this embodiment, a joining region 133 of a certain width is provided around the pitch conversion flow passage 32 of the pitch conversion section 132, and a missing section 84 of the pitch conversion section 132 is provided outside the joining region 133. The missing section 84 of the pitch conversion section 132 is a space that is not filled with resin and overlaps with the common flow passage section 131 but not with the pitch conversion section 132 when viewed from the Z direction. Since the missing section 84 is synonymous with the hollowed-out section, it may be referred to as the hollowed-out section 84 hereinafter instead of the missing section 84.

[0034] By providing the hollowed-out portion 84, it is possible to further suppress the occurrence of sink marks in the pitch conversion member 8. For example, as in the comparative example shown in FIG. 5(b), when there is a pitch conversion flow path sandwiched between pitch conversion flow paths of significantly different lengths, the shape of the hollowed-out portion 84 becomes complex. For this reason, it may be difficult to provide the hollowed-out portion 84 from the viewpoint of mold strength and mold releasability during molding. In contrast, according to the present embodiment, a large and concentrated hollowed-out portion 84 can be provided, and the problems of mold strength and mold releasability can be alleviated. In addition, even if the hollowed-out portion 84 can be provided in the comparative example, the shape of the resin flow region is complex, and pressure loss during filling is likely to increase. On the other hand, according to the present embodiment, the shape of the resin flow region when the hollowed-out portion 84 is provided is simpler than that of the comparative example, and smooth filling of the resin is possible. It is preferable that the depth (height) t1 of the hollowed-out portion 84 is close to the depth t2 of the pitch conversion flow path 32 (pitch conversion flow groove 83) as shown in FIG. 9(b). The depth of the hollowed-out portion (removed portion) 84 is preferably in the range of 0.5 to 2 times the height of the pitch conversion flow channel 32 (pitch conversion flow channel groove 83). As a means for reducing the mold release resistance, a draft may be imparted to the side surface of the hollowed-out portion 84, or an R-shape may be formed on the edge.

[0035] 9(c) and 9(d) are similar to FIGS. 9(a) and 9(b), showing a first modified example of the second embodiment. The (i+1)th pitch-conversion flow passage Pi+1 is disposed on both sides of the ith pitch-conversion flow passage Pi (i is an integer smaller than n), and the outer periphery 88 of the pitch conversion section 132 facing the pitch-conversion flow passage Pi and the pitch-conversion flow passages Pi+1 on both sides is linear. In the illustrated example, for example, the pitch-conversion flow passage P2 is provided on both sides of the pitch-conversion flow passage P1, and the outer periphery 88 facing the pitch-conversion flow passage P1 and the pitch-conversion flow passage P2 is a straight line parallel to the X direction. That is, in the area where the pitch-conversion flow passages longer than the pitch-conversion flow passage are disposed on both sides of the pitch-conversion flow passage, the resin filling section 85 that does not perform the lightening is provided. This reduces the protrusion length of the mold into the narrow area, resulting in a structure that is easier to mold. Since the resin volume in that portion is larger, the sink mark may be larger than if lightening was performed; however, the impact is minor because the difference in length between the adjacent pitch-changing flow passages is small.

[0036] 9(e) and 9(f) are views similar to FIGS. 9(a) and 9(b) showing a second modified example of the second embodiment. As in the first modified example, a resin-filled portion 85 is provided. In FIG. 9(e), the depth of the common flow path 31f located inside and immediately adjacent to the linear outer peripheral portion 88 as viewed from the Z direction is made deeper than the depth of the other common flow paths 31. The common flow path 31f facing the resin-filled portion 85 extends to the region 86, and the thickness of the upper ceiling portion of the common flow path 31f is uniform. As shown in the hatched portion in FIG. 9(f), the region 86 is elongated in the X direction. By adopting such a configuration, it is possible to reduce the problem of releasability of the hollowed portion 84. In addition, since the resin volume is reduced, it is possible to suppress deterioration of sink marks.

[0037] 10(a) and 10(b) are similar to FIGS. 9(a) and 9(b), showing a third modified example of the second embodiment. The (i+1)th pitch conversion flow passage Pi+1 is disposed on both sides of the ith pitch conversion flow passage Pi (i is an integer smaller than n). In the illustrated example, for example, the pitch conversion flow passage P2 is provided on both sides of the pitch conversion flow passage P1. The outer periphery 88 of the pitch conversion section 132 facing the pitch conversion flow passage Pi (pitch conversion flow passage P1 in the illustrated example) and the pitch conversion flow passage Pi+1 (pitch conversion flow passage P2 in the illustrated example) on both sides thereof forms a step formed by an outer periphery 881 and an inner periphery 882. In other words, in the area where the pitch conversion flow passages longer than the pitch conversion flow passage Pi are disposed on both sides of the pitch conversion flow passage Pi, an area 87 having a shallower hollowing out than other areas is provided. The outer periphery 881 is linear, and the inner periphery 882 is recessed toward the pitch conversion flow passage Pi. With this configuration, the resin volume is reduced, making it possible to suppress deterioration of sink marks.

[0038] Figures 10(c) and 10(d) show a fourth modified example of the second embodiment. Figure 10(c) is a schematic cross-sectional view of the pitch conversion member 8, and Figure 10(d) is a perspective view of the pitch conversion member 8. As with the second modified example, the depth of the common flow path 31f located inside the outer peripheral portion 881 and immediately adjacent to the outer peripheral portion 881 when viewed from the Z direction is made deeper than the depth of the other common flow paths 31. This modified example has the same effect as the second modified example. An appropriate one of the above modified examples may be selected depending on the difficulty of molding and the required level of flatness.

[0039] FIG. 11(a) is a plan view of a pitch conversion member 8 showing a fifth modified example of the second embodiment. Any of the first to (i-1)th pitch conversion channels P1 to Pi-1 is arranged on one side of the ith pitch conversion channel Pi (i is an integer smaller than n), and any of the (i+1)th to nth pitch conversion channels Pi+1 to Pn is arranged on the other side. In the illustrated example, for example, pitch conversion channels P1 and P3 are arranged on both sides of the pitch conversion channel P2. The outer periphery 88 of the pitch conversion section 132 facing the ith pitch conversion channel Pi (the pitch conversion channel P2 in the illustrated example) and the pitch conversion channels on both sides thereof (the pitch conversion channels P1 and P3 in the illustrated example) is linear. That is, the thickness in the Z direction of the bonding region 133 provided around the pitch conversion channel 32 does not necessarily need to be the same, and the outer periphery 88 may have a smoother shape. This makes it possible to realize a smooth resin flow and improve the filling property.

[0040] 11(b) is a plan view of the pitch change member 8 showing a sixth modified example of the second embodiment. In this embodiment, the pitch change member 8 has an extension portion 134 that is connected to the pitch change portion 132 and surrounds the cutout portion 84 together with the pitch change portion 132. Both ends of the extension portion 134 are connected to the pitch change portion 132, and the extension portion 134 completely surrounds the cutout portion 84 together with the pitch change portion 132. Although not shown in the figure, only one end of the extension portion 134 may be connected to the pitch change portion 132. Since a joining surface at the same height as the joining region 133 is provided in an area away from the periphery of the pitch change flow channel 32, joining is improved.

[0041] 11(c) is a plan view of the pitch conversion member 8 showing a seventh modified example of the second embodiment. The hollowed-out portion 84 is provided only in a part of the pitch conversion member 8, not over the entire length of the pitch conversion member 8. For example, by providing the hollowed-out portion 84 only in the final filling region R and its vicinity (collectively referred to as the end region E), where sink marks are likely to occur, without providing the hollowed-out portion 84 near the gate, it is possible to suppress sink marks where necessary while keeping the overall mold release resistance small. In this embodiment, the gate G is provided at the center of the pitch conversion member 8 in the longitudinal direction (X direction), so that the cutout portion 84 is provided only in the end region E in the arrangement direction (X direction) of the pitch conversion portions 132.

[0042] In the above two embodiments, the liquid supply path (and liquid recovery path) is composed of three components: the common flow path member 7, the pitch change member 8, and the substrate connection member 9. However, the liquid supply path may be formed of a different component configuration. In the example shown in FIG. 12(a), the pitch change member 8 has the pitch change flow path 32 and the communication hole 82. That is, the pitch change flow path 32 and the communication hole 82 connecting the pitch change flow path 32 and the common flow path 31 are formed in an integrated component (pitch change member 8). In this case, it is possible to remove weight from the front surface of the component, as in the case of FIGS. 9 and 10.

[0043] In the example shown in FIG. 12(b), the pitch conversion member 8 has a pitch conversion flow path 32 and a substrate connection flow path 91 that connects the pitch conversion flow path 32 and the common liquid chamber 22. That is, the pitch conversion flow path 32 and the substrate connection flow path 91 are formed in an integrated member (pitch conversion member 8). The pitch conversion flow path 32 is provided so as to open on the surface opposite to the element substrate 2 side, and the pitch conversion flow path 32 is formed by joining another member 10 to this surface. The member 10 has a communication hole 82 that connects the pitch conversion flow path 32 and the common flow path 31. In the example shown in FIG. 12(c), the pitch conversion member 8 has only the pitch conversion flow path 32. The pitch conversion flow path 32 is formed by joining another member 10 to the pitch conversion member 8. That is, the member having the pitch conversion flow path 32 (pitch conversion member 8), the member 10 having the communication hole 82, and the member having the substrate connection flow path 91 (substrate connection member 9) are formed as separate members. The pitch-conversion flow passage 32 is open on both sides, and the pitch-conversion flow passage 32 is formed by joining the board connection member 9 and the member 10 to both sides. In the examples of Figures 12(b) and 12(c), a cutout having a certain depth may be provided from the front surface or back surface of the member, or a cutout that penetrates from the front surface to the back surface may be provided. [Explanation of symbols]

[0044] 1 Liquid ejection head 22 Common liquid chamber 26 Outlet 31 Common flow path 32 Pitch change channel

Claims

1. A plurality of discharge ports for discharging liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; the first to n-th pitch conversion flow paths connect the first to n-th common flow paths and the first to n-th common liquid chambers, respectively, and have a periphery made of resin; the first to n-th common liquid chambers are located on the side of the first common flow path, the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels, each of which includes one or more of the first to n-th pitch change channels, is repeatedly arranged; the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, n or more pitch change channels other than the n-th pitch change channel are disposed between adjacent n-th pitch change channels; a liquid ejection head, characterized in that each of the pitch-change flow paths other than the nth pitch-change flow path comprises only one section in which the length of the pitch-change flow path monotonically increases and one section in which the length of the pitch-change flow path monotonically decreases.

2. A plurality of discharge ports for discharging liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; the first to n-th pitch conversion flow paths connect the first to n-th common flow paths and the first to n-th common liquid chambers, respectively, and have a periphery made of resin; the first to n-th common liquid chambers are located on the side of the first common flow path, the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels is repeatedly arranged under the condition that each of the first to n-th pitch change channels includes one or more, the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, A liquid ejection head characterized in that, when the numbers of the first to n-th pitch conversion flow channels included in the set are Q1, Q2, ..., Qn, Q1>Qn and Q1≧Q2≧ ... ≧Qn are satisfied.

3. A plurality of discharge ports for discharging liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; the first to n-th pitch conversion flow paths connect the first to n-th common flow paths to the first to n-th common liquid chambers, respectively, and have a periphery made of resin; the first to n-th common liquid chambers are located on the side of the first common flow path, the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels is repeatedly arranged under the condition that each of the first to n-th pitch change channels includes one or more, the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, A pitch change section including the pitch change flow path; a common flow path portion including the first to nth common flow paths; a missing portion of the pitch change portion, the missing portion overlapping the common flow path portion and not overlapping the pitch change portion, when viewed in a height direction of the pitch change flow path.

4. The liquid ejection head according to claim 3 , wherein the defective portion is provided only in an end region in an arrangement direction of the pitch change portion.

5. 5. The liquid ejection head according to claim 3, wherein the height of the defective portion is 0.5 to 2 times the height of the pitch conversion flow path.

6. 6. A liquid ejection head as claimed in any one of claims 3 to 5, wherein an (i+1)th pitch change flow path is arranged on both sides of an ith pitch change flow path (i is an integer smaller than n), and the outer periphery of the pitch change section facing the ith pitch change flow path and the (i+1)th pitch change flow path on both sides thereof is linear.

7. The liquid ejection head according to claim 6 , wherein, when viewed in the height direction, a height of the common flow path located inside and immediately adjacent to the linear outer periphery is higher than a height of the other common flow paths.

8. 6. A liquid ejection head as claimed in any one of claims 3 to 5, wherein an (i+1)th pitch change flow path is arranged on both sides of an ith pitch change flow path (i is an integer smaller than n), and the outer periphery of the pitch change section facing the ith pitch change flow path and the (i+1)th pitch change flow path on both sides thereof forms a step formed by an outer periphery and an inner periphery, the outer periphery is linear, and the inner periphery is recessed toward the ith pitch change flow path.

9. The liquid ejection head according to claim 8 , wherein, when viewed in the height direction, a height of the common flow passage located inside the outer periphery and immediately adjacent to the outer periphery is higher than a height of the other common flow passages.

10. A liquid ejection head according to any one of claims 3 to 5, wherein any one of the 1st to (i-1)th pitch change flow paths is arranged on one side of an ith pitch change flow path (i is an integer smaller than n), and any one of the (i+1)th to nth pitch change flow paths is arranged on the other side, and the outer periphery of the pitch change section facing the ith pitch change flow path and the pitch change flow paths on both sides thereof is linear.

11. The liquid ejection head according to claim 3 , further comprising an extension portion connected to the pitch change portion and surrounding the defective portion together with the pitch change portion.

12. The liquid ejection head according to claim 11 , wherein both ends of the extension portion are connected to the pitch change portion, and the extension portion, together with the pitch change portion, completely surrounds the defective portion.

13. A liquid ejection device comprising: a plurality of ejection ports for ejecting liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; the first to n-th pitch conversion flow paths connect the first to n-th common flow paths to the first to n-th common liquid chambers, respectively, and have a periphery made of resin; the first to n-th common liquid chambers are located on the side of the first common flow path, the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels is repeatedly arranged under the condition that each of the first to n-th pitch change channels includes one or more, the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, A liquid ejection head, characterized in that the first to nth pitch conversion flow paths and communication holes connecting the first to nth pitch conversion flow paths and the first to nth common flow paths are formed from an integral member.

14. A liquid ejection device comprising: a plurality of ejection ports for ejecting liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; the first to n-th pitch conversion flow paths connect the first to n-th common flow paths and the first to n-th common liquid chambers, respectively, and have a periphery made of resin; the first to n-th common liquid chambers are located on the side of the first common flow path, the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels, each of which includes one or more of the first to n-th pitch change channels, is repeatedly arranged; the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, A liquid ejection head characterized in that the first to nth pitch conversion flow paths and substrate connection flow paths connecting the first to nth pitch conversion flow paths and the first to nth common liquid chambers are formed from an integral member.

15. A plurality of discharge ports for discharging liquid; first to n-th common liquid chambers (n is an integer of 3 or more) arranged in parallel, through which the liquid flows and which are connected to the corresponding ejection ports; First to nth common flow paths are arranged in parallel in the order of first to nth, through which the liquid flows; first to n-th pitch conversion flow paths connecting the first to n-th common flow paths and the first to n-th common liquid chambers, respectively; a manufacturing method of a liquid ejection head, the first to n-th common liquid chambers being located on the side of the first common flow path, forming a periphery of the first to nth pitch changing channels with a resin; the arrangement of the first to n-th pitch change channels has a repeating pattern in which a set having a minimum number of pitch change channels, each of which includes one or more of the first to n-th pitch change channels, is repeatedly arranged; the number of pitch change channels in the set is greater than n; At least one of two pitch change channels adjacent to an m-th pitch change channel (m is an integer from 1 to n-2) is any one of the first to (m+1)-th pitch change channels, n or more pitch change channels other than the n-th pitch change channel are disposed between adjacent n-th pitch change channels; A method for manufacturing a liquid ejection head, wherein the pitch change flow paths other than the nth pitch change flow path consist of only one section in which the length of the pitch change flow path monotonically increases and one section in which the length of the pitch change flow path monotonically decreases.

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