JP7750056B2 - Liquid ejection head, inspection method thereof, and manufacturing method thereof - Google Patents

Description

The present invention relates to a liquid ejection head having a stack composed of multiple plates stacked in the stacking direction, as well as an inspection method and manufacturing method for the same.

Patent Document 1 discloses an inkjet head (liquid ejection head) equipped with a flow path unit (laminate) made up of multiple stacked plates. Formed within the flow path unit are flow paths including a common ink chamber, multiple pressure chambers communicating with the common ink chamber, and nozzles communicating with each of the multiple pressure chambers. The flow paths are made up of holes formed in each plate that makes up the flow path unit.

JP 2009-107299 A

In the stack of liquid ejection heads described above, if there is misalignment between the multiple stacked plates, there is a risk that the flow paths will not be formed properly. Therefore, when manufacturing a liquid ejection head, it is necessary to inspect for misalignment between the plates that make up the stack. One possible method of inspecting for misalignment is to use a cone-shaped inspection hole that widens from one side to the other in the stacking direction, formed in each plate that makes up the stack. The hole formed in each plate is largest in the plate located at one end in the stacking direction, and smaller in the plate closer to the other end in the stacking direction.

When inspecting for misalignment, the inspection hole is visually inspected from one end in the stacking direction (the wider end). The inspection is then performed to determine whether the hole in the plate located on one side in the stacking direction (the side closest to the viewing position) of two adjacent plates is entirely within the hole in the plate located on the other side in the stacking direction (the side farthest from the viewing position). If there is misalignment between the two adjacent plates, the edge of the hole in the plate located on the other side in the stacking direction will be hidden by the plate located on one side in the stacking direction.

When manufacturing liquid ejection heads, two plates of the same design (i.e., plates in which the flow path holes that make up the flow paths and the holes that make up the inspection holes are formed in the same pattern) are sometimes stacked on top of each other, for purposes such as reducing the number of different parts. However, even plates of the same design can have variations in hole size due to manufacturing errors, and the hole in the plate located on the other side of the stacking direction (the side farther from the visual position) can be larger than the hole in the plate located on one side of the stacking direction (the side closer to the visual position). In such cases, even if there is no misalignment between the two plates, the edge of the hole in the plate located on the other side of the stacking direction (the side farther from the visual position) will be hidden by the plate located on one side of the stacking direction (the side closer to the visual position). This makes it impossible to accurately inspect for misalignment.

The object of the present invention is to provide a liquid ejection head that can accurately inspect for misalignment even when plates of the same design are stacked consecutively, as well as an inspection method and manufacturing method for the same.

The liquid ejection head of the present invention comprises a stack of plates stacked in a stacking direction, the plates including a first plate having a first flow path hole formed therein that constitutes a flow path, and a second plate having a second flow path hole formed therein that constitutes the flow path, stacked on one side of the first plate in the stacking direction; the stack has a first inspection hole formed by the first hole formed in the plates, and a second inspection hole formed by the second hole formed in the plates; the first inspection hole widens in stages from one side to the other in the stacking direction due to differences in size of the first holes formed in each plate; and the second inspection hole widens in stages from the other side to the one side in the stacking direction due to differences in size of the second holes formed in each plate.

The inspection method of the present invention is an inspection method for inspecting misalignment between multiple plates that constitute a stack in a liquid ejection head, wherein the multiple plates include a first plate and a second plate that are stacked in a stacking direction, the first plate having a first flow path hole that constitutes a flow path, and the second plate having a second flow path hole that constitutes the flow path, and the first plate is stacked on one side of the first plate in the stacking direction, and the stack has a first inspection hole formed by the first hole formed in the multiple plates and a second inspection hole formed by the second hole formed in the multiple plates, and the first inspection hole can be inspected by detecting a difference in size of the first holes formed in each plate from one side to the other side in the stacking direction. The second inspection hole widens in stages from the other side to the one side in the stacking direction due to differences in the sizes of the second holes formed in each plate, and the method includes a first confirmation process in which the first inspection hole is visually inspected from the other side in the stacking direction to confirm whether the edge of the first hole in the second plate is hidden by the first plate, a second confirmation process in which the second inspection hole is visually inspected from the one side in the stacking direction to confirm whether the edge of the second hole in the first plate is hidden by the second plate, and an inspection process in which misalignment between the first plate and the second plate is inspected by at least one of the first confirmation process and the second confirmation process.

Furthermore, the manufacturing method of the present invention is a manufacturing method of a liquid ejection head, and includes a first plate manufacturing process in which a first flow path hole, a first hole, and a second hole that constitute a flow path are formed in a first substrate to manufacture a first plate; a second plate manufacturing process in which a second flow path hole, the first hole, and the second hole that constitute the flow path are formed in a second substrate to manufacture a second plate; a stacking process in which a plurality of plates including the first plate and the second plate are stacked in a stacking direction, in which the second plate is stacked on one side of the first plate in the stacking direction; and a first inspection hole formed by the first holes formed in the plurality of plates, which widens stepwise from one side to the other side in the stacking direction due to differences in the sizes of the first holes formed in each plate. The method includes a first confirmation process in which the first inspection hole, which is formed by the second holes formed in the plurality of plates, is visually inspected from the other side in the stacking direction to confirm whether the edge of the first hole in the second plate is hidden by the first plate; a second confirmation process in which the second inspection hole, which is formed by the second holes formed in the plurality of plates and which gradually widens from the other side toward the one side in the stacking direction due to differences in the sizes of the second holes formed in each plate, is visually inspected from the one side in the stacking direction to confirm whether the edge of the second hole in the first plate is hidden by the second plate; and an inspection process in which misalignment between the first plate and the second plate is inspected by at least one of the first confirmation process and the second confirmation process.

The liquid ejection head, inspection method, and manufacturing method of the present invention allow for inspection of misalignment between the first and second plates by visually inspecting the first inspection hole from the other side of the stacking direction and the second inspection hole from one side of the stacking direction. Here, the tendency for deviation (error) in the size of the holes formed in the same plate from the design value is the same. That is, in the same plate, if the first hole is larger than the design value, the second hole will also be larger than the design value, and if the first hole is smaller than the design value, the second hole will also be smaller than the design value. Therefore, if plates of the same design are used for the first and second plates, the relationship in size due to manufacturing error between the first hole in the first plate and the first hole in the second plate will be the same as the relationship in size due to manufacturing error between the second hole in the first plate and the second hole in the second plate. Therefore, even if the hole in one of the first and second inspection holes in the plate located farther from the visual inspection position is larger than the hole in the plate located closer to the visual inspection position, the hole in the other of the first and second inspection holes in the plate located farther from the visual inspection position will be smaller than the hole in the plate located closer to the visual inspection position. Therefore, even when plates of the same design are stacked in succession, accurate misalignment inspection can be performed using at least one of the first and second inspection holes.

1 is a plan view of a printer equipped with an inkjet head according to an embodiment of the present invention. FIG. 2 is a plan view of the inkjet head shown in FIG. 1 . FIG. 3 is a cross-sectional view of the inkjet head taken along line III-III in FIG. 2. 4A is a cross-sectional view of the inkjet head taken along line IVa-IVa in FIG. 2, and FIG. 4B is a cross-sectional view of the inkjet head taken along line IVb-IVb in FIG. 10A and 10B are diagrams illustrating the first confirmation step, in which (a) shows a case where there is no misalignment between two adjacent plates, and (b) shows a case where there is a misalignment between two adjacent plates. 10A and 10B are diagrams illustrating the case where there is variation in the size of holes formed between two plates of the same design, where (a) shows the first inspection hole and (b) shows the first holes of the two plates. 10A and 10B are diagrams illustrating the case where there is variation in the size of holes formed between two plates of the same design, where (a) shows the second inspection hole and (b) shows the second holes in the two plates.

The following describes a preferred embodiment of the present invention.

<Overall printer configuration>
As shown in FIG. 1, the printer 100 according to this embodiment includes an inkjet head 1 (a liquid ejection head according to the present invention), a carriage 2, guide rails 3a and 3b, a platen 4, transport rollers 5a and 5b, and an ink tank 6.

The carriage 2 is supported by two guide rails 3a and 3b that extend in the horizontal scanning direction (left and right in Figure 1), and moves in the scanning direction along the guide rails 3a and 3b. The inkjet head 1 is mounted on the carriage 2 and moves in the scanning direction together with the carriage 2. In the following explanation, the right side of Figure 1 in the scanning direction will be referred to as "one side," and the left side of Figure 1 will be referred to as "the other side."

Ink of four colors (black, yellow, cyan, and magenta) is supplied to the inkjet head 1 from the ink tank 6 via a pipe (not shown). The inkjet head 1 ejects ink from multiple nozzles 21 opening on its underside, the nozzle surface 11y (see Figures 3 and 4).

The multiple nozzles 21 form nozzle rows 21a along a transport direction (a direction from top to bottom in Figure 1) that is perpendicular to the scanning direction in a plan view. The inkjet head 1 has four nozzle rows 21a aligned in the scanning direction. Black, yellow, cyan, and magenta inks are ejected from the multiple nozzles 21, starting with the nozzle row 21a located at the rightmost position in the scanning direction in Figure 1. The inkjet head 1 will be described in more detail later.

The platen 4 is positioned opposite the nozzle surface 11y, which is the underside of the inkjet head 1, and extends the entire length of the recording paper P in the scanning direction. The platen 4 supports the recording paper P from below. The transport rollers 5a and 5b are positioned upstream and downstream of the carriage 2 in the transport direction, respectively, and transport the recording paper P in the transport direction.

The printer 100 prints on the recording paper P by performing a transport process in which the transport rollers 5a and 5b transport the recording paper P a predetermined distance in the transport direction, and a scanning process in which the carriage 2 moves in the scanning direction and ink is ejected from the multiple nozzles 21 of the inkjet head 1. In other words, the printer 100 is a serial type. In the following description, the direction perpendicular to both the scanning direction and the transport direction is referred to as the up-down direction.

<Configuration of Inkjet Head 1>
Next, the detailed configuration of the inkjet head 1 will be described with reference to Figures 2 to 4. The inkjet head 1 includes a flow path unit 11 and a piezoelectric actuator 12. As shown in Figure 2, the flow path unit 11 has a rectangular shape that is elongated in the transport direction when viewed from above. That is, the flow path unit 11 has four corners 11z when viewed from above. The piezoelectric actuator 12 is disposed on an upper surface 11x of the flow path unit 11.

(Flow path unit 11)
3 and 4, the flow path unit 11 is composed of eleven plates 11a to 11k that are stacked vertically and bonded to one another. The plates 11a to 11k are arranged in this order from top to bottom. The flow path unit 11 corresponds to the "stack" of the present invention.

As shown in FIG. 2, supply ports 31x and return ports 32x open on the upper surface 11x of the flow path unit 11. Four supply ports 31x and four return ports 32x are provided. A flow path 35 extending from the supply ports 31x to the return ports 32x is formed within the flow path unit 11. The flow path 35 includes a plurality of individual flow paths 20, a supply manifold 31, a return manifold 32, and a connecting flow path 33. Note that the individual flow paths 20 are not shown in FIG. 2. Furthermore, as shown in FIG. 3, a damper chamber 30 is formed within the flow path unit 11. Through holes and recesses that form the flow paths 35 and damper chamber 30 are formed in each of the plates 11a to 11k by etching.

As shown in FIG. 2, four supply manifolds 31 and four return manifolds 32 are formed. The supply manifolds 31 and the return manifolds 32 all extend along the transport direction. The four supply manifolds 31 are aligned at equal intervals in the scanning direction. The four return manifolds 32 are also aligned at equal intervals in the scanning direction. As shown in FIG. 3, the return manifolds 32 are located below the supply manifolds 31. Each return manifold 32 overlaps with the corresponding supply manifold 31 in the vertical direction. The vertically overlapping supply manifolds 31 and return manifolds 32 are connected at their downstream ends in the transport direction by a communication flow path 33. Black, yellow, cyan, and magenta inks flow through the four supply manifolds 31 and four return manifolds 32, respectively.

The upstream end of each supply manifold 31 in the transport direction faces a supply port 31x vertically. The supply manifold 31 communicates with the ink tank 6 via the opposing supply port 31x. Furthermore, the upstream end of each return manifold 32 in the transport direction faces a return port 32x vertically. The return manifold 32 communicates with the ink tank 6 via the opposing return port 32x.

As shown in FIG. 3, each of the multiple individual flow paths 20 has a nozzle 21. A pair of supply manifolds 31 and return manifolds 32 arranged vertically is provided in common to the multiple individual flow paths 20, each of which has multiple nozzles 21 included in one nozzle row 21a (see FIG. 1). As shown in FIG. 3, each individual flow path 20 is located on the other side of the supply manifold 31 and return manifold 32 to which the individual flow path 20 is connected, in the scanning direction.

Ink in the ink tank 6 is sent from the supply port 31x to the supply manifold 31. The ink sent to the supply manifold 31 moves from upstream to downstream in the transport direction within the supply manifold 31, and is supplied to each individual flow path 20 (see Figure 3). Ink flowing out of each individual flow path 20 flows into the return manifold 32. Furthermore, ink that reaches the downstream end of the supply manifold 31 in the transport direction flows into the return manifold 32 through the communicating flow path 33. The ink that flows into the return manifold 32 moves from downstream to upstream in the transport direction within the return manifold 32, and is returned to the ink tank 6 via the return port 32x.

As shown in FIG. 3, the supply manifold 31 is composed of a downwardly open recess 31a formed in plate 11c, a through-hole 31b formed in plate 11d, and a through-hole 31c formed in plate 11e. Plate 11d corresponds to the "first plate" in the present invention, and through-hole 31b corresponds to the "first flow path hole" in the present invention. Plate 11e corresponds to the "second plate" in the present invention, and through-hole 31c corresponds to the "second flow path hole" in the present invention.

The return manifold 32 is composed of a downwardly open recess 32a formed in plate 11g, a through-hole 32b formed in plate 11h, and a through-hole 32c formed in plate 11i. Plate 11h corresponds to the "first plate" in this invention, and through-hole 32b corresponds to the "first flow path hole" in this invention. Plate 11i corresponds to the "second plate" in this invention, and through-hole 32c corresponds to the "second flow path hole" in this invention.

A damper chamber 30 is provided between the supply manifold 31 and the return manifold 32 in the vertical direction. The damper chamber 30 is composed of a downwardly open recess formed in plate 11f. The bottom of the recess in plate 11f functions as the damper membrane 31d of the supply manifold 31. The bottom of the recess 32a that constitutes the return manifold 32 in plate 11g functions as the damper membrane 32d of the return manifold 32.

Plates 11a to 11c are formed with through holes (not shown) that connect the supply port 31x to the upstream end of the supply manifold 31 in the transport direction. Plates 11a to 11g are formed with through holes (not shown) that connect the return port 32x to the upstream end of the return manifold 32 in the transport direction. Plates 11f and 11g are also formed with through holes (not shown) that form the communicating flow path 33. The through holes that form the communicating flow path 33 are formed at positions sandwiched between the downstream ends of the pair of supply manifolds 31 and return manifolds 32 that are aligned vertically.

As shown in FIG. 3, each individual flow path 20 includes a nozzle 21, a pressure chamber 22, a connecting flow path 23 consisting of a first flow path 23a and a second flow path 23b, an inflow flow path 24, and an outflow flow path 25.

The nozzles 21 are formed as through-holes in the plate 11k, and open to the nozzle surface 11y, which is the lower surface of the flow path unit 11. The pressure chambers 22 are formed as through-holes in the plate 11a, and open to the upper surface 11x of the flow path unit 11. An inlet flow path 24 is connected to one end of the pressure chamber 22 in the scanning direction, and a connection flow path 23 is connected to the other end of the pressure chamber 22 in the scanning direction.

The connection flow path 23 connects the nozzle 21 and the pressure chamber 22 to each other. The first flow path 23a of the connection flow path 23 is composed of a through hole formed in plate 11j. The first flow path 23a overlaps with the nozzle 21 in a top view. In other words, the nozzle 21 is connected midway through the first flow path 23a. The second flow path 23b of the connection flow path 23 is composed of a through hole formed in plates 11b to 11i and extends in the vertical direction. The second flow path 23b is separated from the nozzle 21 in the scanning direction and connects the pressure chamber 22 and the first flow path 23a.

The inflow channel 24 connects the supply manifold 31 and the pressure chamber 22 to each other. The inflow channel 24 is composed of a recess formed in plate 11b that opens downward, a through-hole located at the other end of the recess in the scanning direction, and a through-hole formed in plate 11c. The inflow channel 24 is connected to the pressure chamber 22 via a through-hole formed in plate 11b. The inflow channel 24 is also connected to the supply manifold 31 via a through-hole formed in the bottom of a recess 31a formed in plate 11c. The cross-sectional area of the inflow channel 24 in a plane perpendicular to the scanning direction (ink flow direction) is smaller than that of the pressure chamber 22, and it functions as a throttle.

The outflow channel 25 connects the first channel 23a of the connecting channel 23 to the return manifold 32. The outflow channel 25 is connected to the first channel 23a on the opposite side of the nozzle 21 from the second channel 23b in the scanning direction. The outflow channel 25 is composed of a downwardly open recess formed in the plate 11j and a through-hole located at one end of the recess in the scanning direction. The outflow channel 25 is connected to the return manifold 32 via the through-hole formed in the plate 11j. The other end of the recess in the plate 11j that forms the outflow channel 25 in the scanning direction is connected to the through-hole that forms the first channel 23a of the connecting channel 23. The outflow channel 25 has a smaller cross-sectional area in a plane perpendicular to the scanning direction (ink flow direction) than the first channel 23a of the connecting channel 23, and functions as a throttle.

Ink supplied from the supply manifold 31 to each individual flow path 20 flows into the pressure chamber 22 through the inflow flow path 24, moves approximately horizontally within the pressure chamber 22, and flows into the connecting flow path 23. The ink that flows into the connecting flow path 23 moves downward in the second flow path 23b, and then flows into the first flow path 23a, which extends in the horizontal plane. Some of the ink that flows into the first flow path 23a is ejected from the nozzle 21, and the remainder flows into the return manifold 32 through the outflow flow path 25.

By circulating ink between the ink tank 6 and the flow path unit 11 in this way, air is discharged from the supply manifold 31 and return manifold 32 formed in the flow path unit 11, as well as from the individual flow paths 20, and ink viscosity is prevented from increasing. Furthermore, if the ink contains sedimentation components (components that may cause sedimentation, such as pigments), these components are agitated to prevent sedimentation.

As shown in FIG. 2, the flow path unit 11 also has a first inspection hole 41 and a second inspection hole 42 for inspecting misalignment between the plates 11a to 11k. The first inspection hole 41 and the second inspection hole 42 are both through holes that open to both the top surface 11x and the nozzle surface 11y of the flow path unit 11. The first inspection hole 41 and the second inspection hole 42 are both circular. The first inspection hole 41 is provided at one of the four corners 11z of the flow path unit 11 that is on the upstream side in the transport direction and on the other side in the scanning direction. The second inspection hole 42 is provided at one of the four corners 11z of the flow path unit 11 that is on the upstream side in the transport direction and on one side in the scanning direction.

As shown in FIG. 4(a), the first inspection holes 41 are composed of first holes 41a to 41k formed in plates 11a to 11k, respectively. The first holes 41a to 41k are formed by etching. The sizes of the first holes 41a to 41k are designed so that the first inspection holes 41 widen in stages from the lower side (one side in the stacking direction) to the upper side (the other side in the stacking direction) due to differences in the sizes of the first holes 41a to 41k. In other words, the first holes 41a to 41k are designed so that the first hole 41a formed in the uppermost plate 11a is the largest, and the first holes formed in the lower plates are smaller.

As shown in FIG. 4(b), the second inspection holes 42 are composed of second holes 42a to 42k formed in plates 11a to 11k, respectively. The second holes 42a to 42k are formed by etching. The sizes of the second holes 42a to 42k are designed so that the second inspection holes 42 widen in stages from the upper side (the other side in the stacking direction) to the lower side (one side in the stacking direction) due to differences in the sizes of the second holes 42a to 42k. In other words, the second holes 42a to 42k are designed so that the second hole 42k formed in the lowest plate 11k is the largest, and the second holes formed in the higher plates are smaller.

The plates 11d and 11e, in which the through holes 31b and 31c that make up the supply manifold 31 are formed, are of the same design. That is, in plates 11d and 11e, the through holes (through holes 31b and 31c) that make up the supply manifold 31, the through holes that make up the connection flow path 23, the first holes (first holes 41d and 41e) that make up the first inspection hole 41, and the second holes (second holes 42d and 42e) that make up the second inspection hole 42 are formed in the same pattern.

Therefore, the design values of the sizes of the first holes 41d, 41e that constitute the first inspection holes 41 formed in plates 11d, 11e, respectively, are the same. Furthermore, the design values of the sizes of the second holes 42d, 42e that constitute the second inspection holes 42 formed in plates 11d, 11e, respectively, are also the same.

Similarly, plates 11h and 11i, in which the through holes 32b and 32c that make up the return manifold 32 are formed, are also made of the same design. Therefore, the design values of the sizes of the first holes 41h and 41i that make up the first inspection hole 41 formed in plates 11h and 11i are the same. Furthermore, the design values of the sizes of the second holes 42h and 42i that make up the second inspection hole 42 formed in plates 11h and 11i are also the same.

(Piezoelectric actuator 12)
As shown in FIG. 3, the piezoelectric actuator 12 includes, from the bottom up, a vibration plate 12a, a common electrode 12b, a piezoelectric layer 12c, and a plurality of individual electrodes 12d.

The vibration plate 12a is disposed on the upper surface 11x of the flow path unit 11. In the area of the upper surface of the vibration plate 12a facing the multiple pressure chambers 22, a common electrode 12b, a piezoelectric layer 12c, and an individual electrode 12d are arranged, stacked in this order from bottom to top. The vibration plate 12a, common electrode 12b, and piezoelectric layer 12c are arranged across the multiple pressure chambers 22. An individual electrode 12d is provided for each pressure chamber 22, and overlaps each pressure chamber 22 when viewed from above.

The common electrode 12b and the multiple individual electrodes 12d are connected to a driver IC (not shown) via wiring members (not shown). The driver IC maintains the potential of the common electrode 12b at ground potential while changing the potential of the individual electrodes 12d. As a result, the portion of the vibration plate 12a and piezoelectric layer 12c sandwiched between the individual electrode 12d and the pressure chamber 22 (actuator 12x) deforms so as to become convex toward the pressure chamber 22. This deformation reduces the volume of the pressure chamber 22, increasing the pressure of the ink within the pressure chamber 22, and ink is ejected from the nozzle 21 connected to the pressure chamber 22. In other words, the piezoelectric actuator 12 has multiple actuators 12x corresponding to each pressure chamber 22.

<Method of manufacturing inkjet head 1>
Next, a method for manufacturing the inkjet head 1 will be described.

(First Plate Manufacturing Process, Second Plate Manufacturing Process)
First, eleven substrates that will become plates 11a to 11k are prepared. Then, through holes and recesses that form the flow path 35, the damper chamber 30, the first inspection hole 41, and the second inspection hole 42 are formed in the eleven substrates by etching, thereby producing plates 11a to 11k. When producing plates 11d and 11e, the same photomask is used to pattern photoresist. As a result, the through holes 31b and 31c that form the supply manifold 31, the through holes that form the connection flow path 23, the first holes 41d and 41e that form the first inspection hole 41, and the second holes 42d and 42e that form the second inspection hole 42 are formed in the same pattern on plates 11d and 11e. Furthermore, when producing plates 11h and 11i, the same photomask is used to pattern photoresist. As a result, the through holes 32b, 32c that constitute the return manifold 32, the through holes that constitute the connection flow path 23, the first holes 41h, 41i that constitute the first inspection hole 41, and the second holes 42h, 42i that constitute the second inspection hole 42 are formed in the same pattern on the plates 11h, 11i.

(Lamination process)
Next, the eleven plates 11a to 11k thus fabricated are stacked in a stacking direction. Here, the side that will be on the bottom when the inkjet head 1 is in use is referred to as "one side in the stacking direction," and the side that will be on the top is referred to as "the other side in the stacking direction." The eleven plates 11a to 11k are stacked in this order from the other side to the one side. That is, plate 11e is stacked on one side of plate 11d. Furthermore, plate 11i is stacked on one side of plate 11h.

At this time, the first holes 41a to 41k formed in each plate 11a to 11k form a first inspection hole 41 that widens in stages from one side to the other. Furthermore, the second holes 42a to 42k formed in each plate 11a to 11k form a second inspection hole 42 that widens in stages from the other side to one side.

Next, the plates 11a to 11k stacked in the stacking process are inspected for misalignment. The misalignment inspection includes the first confirmation process, second confirmation process, and inspection process, which will be described later.

(First confirmation process)
In the first confirmation step, the first inspection hole 41 is visually inspected from the other side (wider side) in the stacking direction, and it is checked whether the edge of the first hole of the plate located on one side (farther from the visual inspection position) of two plates adjacent in the stacking direction is hidden by the plate located on the other side (closer to the visual inspection position) in the stacking direction.

That is, for example, when focusing on plates 11a and 11b, it is confirmed whether the edge of the first hole 41b of plate 11b, which is located on one side in the stacking direction, is hidden by plate 11a, which is located on the other side in the stacking direction. If there is no misalignment between plates 11a and 11b, the entire first hole 41b of plate 11b will be inside the first hole 41a of plate 11a, as shown in Figure 5(a). On the other hand, if there is a misalignment between plates 11a and 11b, the edge of the first hole 41b of plate 11b will be hidden by plate 11a, as shown in Figure 5(b).

(Second confirmation process)
In the second confirmation step, the second inspection hole 42 is visually inspected from one side in the stacking direction (the wider side), and it is checked whether the edge of the second hole of the plate located on the other side in the stacking direction (the side farther from the visual inspection position) of two plates adjacent in the stacking direction is hidden by the plate located on the one side in the stacking direction (the side closer to the visual inspection position).

(Inspection process)
In the inspection step, misalignment between two plates adjacent in the stacking direction is inspected by at least one of a first confirmation step and a second confirmation step.

Among pairs of plates adjacent in the stacking direction, misalignment between plates can be inspected by performing the first confirmation process, except for pairs of plates that have the same design and are adjacent in the stacking direction. In other words, by performing the first confirmation process, misalignment between plates can be inspected between plates 11a and 11b, between plates 11b and 11c, between plates 11c and 11d, between plates 11e and 11f, between plates 11f and 11g, between plates 11g and 11h, between plates 11i and 11j, and between plates 11j and 11k.

In other words, in the first confirmation process, if the edge of the first hole in the plate located farthest from the visual inspection position is not hidden by the plate located closer to the visual inspection position, it is determined that there is no misalignment between the plates. Furthermore, if the edge of the first hole in the plate located farthest from the visual inspection position is hidden by the plate located closer to the visual inspection position, it is determined that there is a misalignment between the plates. In this embodiment, a second confirmation process is also performed on these plate pairs in order to improve inspection accuracy.

As described above, plates 11d and 11e have the same design, and the design values for the sizes of the first holes 41d and 41e that constitute the first inspection hole 41 formed in plates 11d and 11e are the same. However, due to manufacturing errors, as shown in FIG. 6(a), the first hole 41e in plate 11e located on one side of the stacking direction (the side farther from the visual position) may be larger than the first hole 41d in plate 11d located on the other side of the stacking direction (the side closer to the visual position). In such cases, as shown in FIG. 6(b), even if there is no misalignment between plates 11d and 11e, the edge of the first hole 41e in plate 11e may be hidden by plate 11d. Therefore, the presence or absence of misalignment between plates 11d and 11e may not be determined simply by performing the first confirmation process in which the first inspection hole 41 is visually inspected.

Furthermore, plates 11h and 11i are also plates of the same design. Therefore, as with plates 11d and 11e, the presence or absence of misalignment between plates 11h and 11i may not be determined simply by performing the first confirmation step of visually inspecting the first inspection hole 41.

For the same plate, the deviation (error) in the size of the formed holes from the design value tends to be the same. That is, for the same plate, if the first hole is larger than the design value, the second hole will also be larger than the design value, and if the first hole is smaller than the design value, the second hole will also be smaller than the design value. Therefore, for plates 11d and 11e of the same design, the size relationship due to manufacturing error between the first hole 41d of plate 11d and the first hole 41e of plate 11e will be the same as the size relationship due to manufacturing error between the second hole 42d of plate 11d and the second hole 42e of plate 11e.

Therefore, for example, as shown in FIG. 6(a), if the first hole 41e in plate 11e is larger than the first hole 41d in plate 11d, then the second hole 42e in plate 11e will also be larger than the second hole 42d in plate 11d, as shown in FIG. 7(a). As described above, if the first hole 41e in plate 11e is larger than the first hole 41d in plate 11d, when the first inspection hole 41 is viewed from the other side, the edge of the first hole 41e in plate 11e will be hidden by plate 11d, even if there is no misalignment between plates 11d and 11e, as shown in FIG. 6(b). On the other hand, when the second inspection hole 42 is viewed from one side, as shown in FIG. 7(b), the entire second hole 42d in plate 11d will fit within the second hole 42e in plate 11e if there is no misalignment between plates 11d and 11e.

Therefore, for a pair of plates of the same design that are adjacent in the stacking direction, if it is confirmed in either the first or second confirmation process that the edge of the first or second hole in the plate located farther from the visual position is not hidden by the plate located closer to the visual position, it can be determined that there is no misalignment between the plates. Furthermore, if it is confirmed in both the first and second confirmation processes that the edge of the second hole in the plate located farther from the visual position is hidden by the plate located closer to the visual position, it can be determined that there is misalignment between the plates.

That is, for pairs of plates 11d, 11e and plates 11h, 11i that have the same design and are adjacent in the stacking direction, misalignment between the plates can be inspected using at least one of the first and second confirmation processes. As mentioned above, for pairs of plates that have different designs and are adjacent in the stacking direction, misalignment between the plates can be inspected using only the first confirmation process. However, inspection accuracy can be improved by also performing the second confirmation process on pairs of plates that have different designs and are adjacent in the stacking direction.

If misalignment between two adjacent plates in the stacking direction is found during the inspection process, the positions of the two plates are adjusted to align them. After adjusting the positions of all plate pairs to eliminate misalignment, plates 11a to 11k are bonded to each other to complete the flow path unit 11. Finally, a piezoelectric actuator 12 is bonded to the top surface 11x of the flow path unit 11 to complete the inkjet head 1.

<Features of the embodiment>
As described above, the inkjet head 1 of the above-described embodiment includes a flow path unit 11 composed of eleven plates 11a to 11k stacked vertically. Each plate 11a to 11k has a through hole and a recess that form a flow path 35. The flow path unit 11 also includes a first inspection hole 41 composed of first holes 41a to 41k formed in each of the plates 11a to 11k, and a second inspection hole 42 composed of second holes 42a to 42k formed in each of the plates 11a to 11k. The first inspection hole 41 gradually widens from one side to the other in the stacking direction due to the difference in size of the first holes 41a to 41k formed in each of the plates 11a to 11k. The second inspection hole 42 gradually widens from the other side to one side in the stacking direction due to the difference in size of the second holes 42a to 42k formed in each of the plates 11a to 11k.

The manufacturing method of the inkjet head 1 of the above-described embodiment includes the steps of forming through holes and recesses that respectively constitute the flow path 35, the first inspection hole 41, and the second inspection hole 42 in 11 substrates to fabricate the plates 11a to 11k (first plate fabrication step and second plate fabrication step), stacking the fabricated 11 plates 11a to 11k in the stacking direction (stacking step), and visually inspecting the first inspection hole 41 from the other side in the stacking direction to determine the first hole of the plate located on one side of the stacking direction between two adjacent plates. The method includes a step (first confirmation step) of checking whether the edge of the hole is hidden by the plate located on the other side in the stacking direction, a step (second confirmation step) of visually inspecting the second inspection hole 42 from one side in the stacking direction to check whether the edge of the second hole in the plate located on the other side in the stacking direction of two adjacent plates is hidden by the plate located on one side in the stacking direction, and a step (inspection step) of inspecting for misalignment between the two adjacent plates using at least either the first confirmation step or the second confirmation step.

With the above-described configuration, misalignment between plates 11a-11k can be inspected by visually inspecting the first inspection hole 41 from the other side of the stacking direction and the second inspection hole 42 from one side of the stacking direction. Here, the tendency for deviation (error) of the hole size from the design value is the same for the same plate. That is, for the same plate, if the first hole is larger than the design value, the second hole will also be larger than the design value, and if the first hole is smaller than the design value, the second hole will also be smaller than the design value. Therefore, if two adjacent plates have the same design, the relationship between the first hole of one plate and the first hole of the other plate due to manufacturing error will be the same as the relationship between the second hole of one plate and the second hole of the other plate due to manufacturing error. Therefore, even if the hole in the plate located farther from the visual inspection position for one of the first inspection holes 41 and second inspection holes 42 is larger than the hole in the plate located closer to the visual inspection position for the other of the first inspection holes 41 and second inspection holes 42, the hole in the plate located farther from the visual inspection position will be smaller than the hole in the plate located closer to the visual inspection position. Therefore, even when plates of the same design are stacked in succession, accurate misalignment inspection can be performed using at least one of the first inspection holes 41 and second inspection holes 42.

In addition, in the inkjet head 1 of this embodiment, the through holes and recesses that form the flow path 35 and damper chamber 30, the first holes 41a to 41k that form the first inspection hole 41, and the second holes 42a to 42k that form the second inspection hole 42 are formed in each plate 11a to 11k by etching. This makes it easy to form the holes.

Furthermore, in the inkjet head 1 of this embodiment, the first inspection hole 41 and the second inspection hole 42 are circular. Therefore, the first inspection hole 41 and the second inspection hole 42 are easier to form than when the first inspection hole 41 and the second inspection hole 42 are polygonal, etc. Furthermore, the first inspection hole 41 and the second inspection hole 42 make it easy to inspect for plate misalignment.

In addition, in the inkjet head 1 of this embodiment, the flow path unit 11 has a rectangular shape with four corners 11z when viewed from above. The first inspection hole 41 is formed in one of the four corners 11z, and the second inspection hole 42 is formed in a different corner 11z from the corner 11z where the first inspection hole 41 is formed. Therefore, misalignment inspection can be performed using the first inspection hole 41 and the second inspection hole 42, which are formed in different corners 11z, thereby improving the accuracy of misalignment inspection.

Furthermore, in the inkjet head 1 of this embodiment, the flow path 35 includes multiple individual flow paths 20, each including a nozzle 21 that ejects ink, and a supply manifold 31 and a return manifold 32 that are common to the multiple individual flow paths 20. Through holes 31b and 31c that form the supply manifold 31 are formed in two plates adjacent to each other in the stacking direction. Through holes 32b and 32c that form the return manifold 32 are formed in two plates adjacent to each other in the stacking direction. The supply manifold 31 and the return manifold 32 have larger volumes than the individual flow paths 20, and are often configured by stacking plates of the same design. Even when plates 11d and 11e, in which the through holes 31b and 31c that form the supply manifold 31 are formed, have the same design, this embodiment allows for accurate misalignment inspection. Even when plates 11h and 11i, in which the through holes 32b and 32c that form the return manifold 32 are formed, have the same design, this embodiment allows for accurate misalignment inspection.

Although embodiments of the present invention have been described above with reference to the drawings, the specific configuration should not be considered limited to these embodiments. The scope of the present invention is indicated by the claims rather than the above description of the embodiments, and further includes all modifications within the meaning and scope of the claims.

In other words, in the above embodiment, the first and second confirmation processes are performed for all combinations of two adjacent plates among the 11 plates 11a to 11k that make up the flow path unit 11, but this is not limited to this. For pairs of plates that have different designs and are adjacent in the stacking direction, it is sufficient to perform only one of the first and second confirmation processes.

In addition, in the above-described embodiment, the first inspection hole 41 and the second inspection hole 42 are described as through holes, but this is not limited to this. For example, if the first inspection hole 41 is a through hole, the second inspection hole 42 may be composed of second holes 42d to 42k formed in plates 11d to 11k, with the other side in the stacking direction blocked. In this case, only the first confirmation process is performed for pairs of plates that are different in design and adjacent in the stacking direction. In the second confirmation process, the second inspection hole 42 is visually inspected from one side in the stacking direction, and confirmation work is performed between plates 11d and 11e and between plates 11h and 11i of the same design. Similarly, if the second inspection hole 42 is a through hole, the first inspection hole 41 may be composed of first holes 41a to 41i formed in plates 11a to 11i, with one side in the stacking direction blocked.

Furthermore, in the above embodiment, the flow path unit 11 is described as being composed of eleven plates 11a to 11k, but the number of plates that make up the flow path unit 11 is not limited to this. The number of plates that make up the flow path unit 11 may be two or more.

In addition, in the above-described embodiment, a case has been described in which a flow path 35 including a plurality of individual flow paths 20, a supply manifold 31, a return manifold 32, and a communicating flow path 33 is formed within the flow path unit 11, but the configuration of the flow path 35 is not limited to this. That is, for example, a case may be in which only a supply manifold 31 is formed without a return manifold 32, or neither a supply manifold 31 nor a return manifold 32 may be formed. Furthermore, in the above-described embodiment, a case has been described in which four supply manifolds 31 and four return manifolds 32 are formed, but the number of supply manifolds 31 and four return manifolds 32 is not limited to four. The number of supply manifolds 31 and four return manifolds 32 may also be different.

In addition, in the above embodiment, the through holes 31b and 31c that form the supply manifold 31 are formed in plates 11d and 11e, and the through holes 32b and 32c that form the return manifold are formed in plates 11h and 11i. However, this is not limited to this. For example, the through holes that form the supply manifold 31 may be formed in each of two adjacent plates, and the through holes that form the return manifold 32 may also be formed in the same two plates.

Furthermore, in the above-described embodiment, the through holes and recesses formed in each of the plates 11a to 11k were described as being formed by etching, but this is not limited to this. The through holes and recesses may also be formed by other methods, such as laser processing.

Furthermore, in the above-described embodiment, the flow path unit 11 has a rectangular shape having four corners 11z when viewed from above, and the first inspection hole 41 and the second inspection hole 42 are formed at different corners 11z, but this is not limited to this. The first inspection hole 41 and the second inspection hole 42 may be formed at the same corner 11z, or at a location other than the corner 11z. The first inspection hole 41 and the second inspection hole 42 only need to be formed in a position that is not connected to the through holes and recesses that make up the flow path 35. Furthermore, the flow path unit 11 may have a polygonal shape other than a rectangle when viewed from above, or may have a circular or elliptical shape that has no corners.

In addition, in the above embodiment, the plates 11d and 11e in which the through holes 31b and 31c forming the supply manifold 31 are formed are plates of the same design, and the plates 11h and 11i in which the through holes 32b and 32c forming the return manifold 32 are formed are plates of the same design, but this is not limited to this. That is, only plates 11d and 11e may be plates of the same design, or only plates 11h and 11i may be plates of the same design. Furthermore, plates of the same design may be used for two adjacent plates in the stacking direction in which flow path holes (holes or recesses) forming flow paths 35 other than the supply manifold 31 and the return manifold 32 are formed.

Furthermore, while the above-described embodiment describes a serial type in which the inkjet head 1 moves in the scanning direction, this is not limited to this. In other words, the present invention can also be applied to a line-type inkjet head in which the inkjet head is fixed.

The present invention can also be applied to liquid ejection heads that eject liquids other than ink. Furthermore, the object to be ejected is not limited to recording paper P, but may also be, for example, cloth, a substrate, etc.

1. Inkjet head (liquid ejection head)
11 Flow path unit (laminated body)
11d Plate (first plate)
11e Plate (second plate)
11h Plate (first plate)
11i plate (second plate)
11z Corner portion 20 Individual flow path 21 Nozzle 31 Supply manifold 31b Through hole (first flow path hole)
31c through hole (second flow path hole)
32 Return manifold 32b Through hole (first flow path hole)
32c through hole (second flow path hole)
41 First inspection holes 41a to 41k First holes 42 Second inspection holes 42a to 42k Second holes

Claims (7)

a stacked body made up of a plurality of plates stacked in a stacking direction,
The plurality of plates include:
a first plate having a first flow path hole formed therein that constitutes a flow path;
a second plate having a second flow path hole that configures the flow path, the second plate being stacked on one side of the first plate in the stacking direction,
The laminate is
a first inspection hole formed by a first hole formed in the plurality of plates;
a second inspection hole formed by a second hole formed in the plurality of plates;
the first inspection hole widens stepwise from one side to the other side in the stacking direction due to a difference in size of the first holes formed in each plate,
A liquid ejection head characterized in that the second inspection hole gradually widens from the other side to the one side in the stacking direction due to differences in the sizes of the second holes formed in each plate. The liquid ejection head described in claim 1, wherein the first flow path hole, the second flow path hole, the first hole, and the second hole are formed by etching. A liquid ejection head according to claim 1 or 2, characterized in that the first inspection hole and the second inspection hole are circular. the laminate has a polygonal shape having a plurality of corners when viewed from the stacking direction,
the first inspection hole is formed in one of the plurality of corners,
4. The liquid ejection head according to claim 1, wherein the second inspection hole is formed in a corner of the plurality of corners that is different from the one corner. the flow path includes a plurality of individual flow paths each including a nozzle for ejecting a liquid, and a manifold provided in common to the plurality of individual flow paths;
5. The liquid ejection head according to claim 1, wherein the first flow path hole and the second flow path hole both constitute the manifold. 1. An inspection method for inspecting misalignment between a plurality of plates constituting a stack of plates in a liquid ejection head, comprising:
the plurality of plates include a first plate and a second plate stacked in a stacking direction, the first plate having a first flow path hole that forms a flow path, the second plate having a second flow path hole that forms the flow path, and the second plate being stacked on one side of the first plate in the stacking direction;
the stack has a first inspection hole formed by a first hole formed in the plurality of plates and a second inspection hole formed by a second hole formed in the plurality of plates,
the first inspection hole widens stepwise from one side to the other side in the stacking direction due to a difference in size of the first holes formed in each plate,
the second inspection hole widens in a stepwise manner from the other side toward the one side in the stacking direction due to a difference in size of the second holes formed in each plate,
a first confirmation step of visually checking the first inspection hole from the other side in the stacking direction to confirm whether an edge of the first hole in the second plate is hidden by the first plate;
a second confirmation step of visually checking the second inspection hole from the one side in the stacking direction to confirm whether an edge of the second hole in the first plate is hidden by the second plate;
an inspection step of inspecting misalignment between the first plate and the second plate by at least one of the first confirmation step and the second confirmation step. A method for manufacturing a liquid ejection head, comprising:
a first plate fabrication step of fabricating a first plate by forming a first flow path hole, a first hole, and a second hole that form a flow path in a first substrate;
a second plate fabrication step of fabricating a second plate by forming a second flow path hole, the first hole, and the second hole in a second substrate, the second flow path hole constituting the flow path;
a step of stacking a plurality of plates including the first plate and the second plate in a stacking direction, the step of stacking the second plate on one side of the first plate in the stacking direction;
a first confirmation step of visually inspecting a first inspection hole constituted by the first holes formed in the plurality of plates, the first inspection hole widening stepwise from one side to the other side in the stacking direction due to differences in size of the first holes formed in each plate, from the other side in the stacking direction, to confirm whether an edge of the first hole in the second plate is hidden by the first plate;
a second confirmation step of visually inspecting, from the one side in the stacking direction, a second inspection hole constituted by the second holes formed in the plurality of plates, the second inspection hole widening in stages from the other side toward the one side in the stacking direction due to differences in size of the second holes formed in each plate, and confirming whether an edge of the second hole in the first plate is hidden by the second plate;
an inspection step of inspecting misalignment between the first plate and the second plate by at least one of the first confirmation step and the second confirmation step.