Liquid injection head and liquid injection device

Abstract

The present invention provides a liquid injection head and liquid injection device that can detect whether the pressure of the nozzle meniscus is within a normal range while suppressing increases in cost and size. [Solution] The device comprises a plurality of nozzles 21 for spraying liquid, a plurality of pressure chambers 12 arranged in the -X direction to which pressure is applied to the liquid for spraying from each of the plurality of nozzles 21, a first liquid chamber 81 positioned in the -X direction relative to a first pressure chamber 12A located at the -X end of the plurality of pressure chambers 12, a first diaphragm 50A defining a part of the first liquid chamber 81, and a manifold commonly connected to the plurality of pressure chambers 12 and the first liquid chamber 81, and has a strain gauge 70 corresponding to the first diaphragm 50A for obtaining the pressure in the first liquid chamber 81.

Description

Technical Field

[0001] The present invention relates to a liquid injection head for injecting a liquid from a nozzle and a liquid injection device, and particularly to an inkjet recording head for injecting ink as a liquid and an inkjet recording device.

Background Art

[0002] A liquid injection device typified by an inkjet recording device such as an inkjet printer or a plotter includes a liquid injection head capable of injecting a liquid such as ink stored in a cartridge, a tank, or the like as liquid droplets.

[0003] For example, the liquid injection head disclosed in Patent Document 1 includes a nozzle for injecting a liquid, a pressure chamber communicating with the nozzle, and a pressure detector provided individually for a plurality of pressure chambers. The pressure detector enables measurement of the pressure of the liquid (meniscus) near the pressure chamber.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In such a conventional technique, since a pressure detector corresponding individually to all the pressure chambers is provided, it is possible to detect whether or not the pressure of the meniscus of each nozzle is normally maintained within the range of the meniscus pressure resistance. However, if the pressures of the menisci near all the pressure chambers are measured individually, the cost increases and the size of the liquid injection head becomes larger. It is desired to be able to detect whether or not the pressure of the meniscus of the nozzle included in the liquid injection head is within a normal range while suppressing an increase in cost and an increase in size.

Means for Solving the Problems

[0006] An aspect of the present invention that solves the above problems is a liquid spray head comprising: a plurality of nozzles for spraying liquid; a plurality of pressure chambers arranged in a first direction, each of which pressure for spraying liquid from the plurality of nozzles is applied to the liquid; a first liquid chamber positioned in the first direction relative to the first pressure chamber located at the end of the plurality of pressure chambers in the first direction; a first diaphragm defining a part of the first liquid chamber; and a first common liquid chamber connected in common to the plurality of pressure chambers and the first liquid chamber, wherein the head has a first detection element corresponding to the first diaphragm for obtaining the pressure in the first liquid chamber.

[0007] Another aspect of the present invention is a liquid injection device characterized by comprising the liquid injection head according to the above aspect and a pressure acquisition unit that acquires the pressure of the first liquid chamber based on the resistance value of the first detection element. [Brief explanation of the drawing]

[0008] [Figure 1] This figure shows the schematic configuration of the liquid injection device according to Embodiment 1. [Figure 2] This is a block diagram of a liquid injection device according to Embodiment 1. [Figure 3] This is an exploded perspective view of the liquid injection head according to Embodiment 1. [Figure 4] This is a cross-sectional view of the liquid injection head according to Embodiment 1. [Figure 5] This is an exploded perspective view of the head chip according to Embodiment 1. [Figure 6] This is a plan view of the head chip according to Embodiment 1. [Figure 7] This is a cross-sectional view taken along the line A-A' in Figure 6, relating to Embodiment 1. [Figure 8] This is a cross-sectional view taken along the line B-B' in Figure 6, relating to Embodiment 1. [Figure 9] This is a plan view showing the flow path of the head tip according to Embodiment 1. [Figure 10]This figure shows an example of a strain gauge and pressure detection unit according to Embodiment 1. [Figure 11] This is a cross-sectional view of the main part of the head chip according to a modified example 1 of Embodiment 1. [Figure 12] This is a plan view showing the flow path of a head tip according to a modified example 2 of Embodiment 1. [Figure 13] This figure shows an example of a strain gauge and pressure detection unit according to a modified example 3 of Embodiment 1. [Figure 14] This is a block diagram of a liquid injection device according to a modified example 6 of Embodiment 1. [Figure 15] This is a plan view showing the flow path of the head tip according to Embodiment 2. [Figure 16] This is a cross-sectional view taken along the line C-C' in Figure 15, relating to Embodiment 2. [Figure 17] This is a cross-sectional view taken along the line D-D' in Figure 15, relating to Embodiment 2. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below based on embodiments. However, the following description represents one aspect of the present invention and can be arbitrarily modified within the scope of the invention. In each figure, the same reference numerals indicate the same components, and their descriptions are omitted as appropriate. In each figure, X, Y, and Z represent three mutually orthogonal spatial axes. In this specification, the directions along these axes are referred to as the X direction, Y direction, and Z direction. In each figure, the direction in which the arrow points is described as the positive (+) direction, and the opposite direction of the arrow is described as the negative (-) direction. Furthermore, the Z direction indicates the vertical direction, with the +Z direction indicating vertically downward and the -Z direction indicating vertically upward. In addition, the directions of the three spatial axes that are not limited to positive and negative directions will be described as the X-axis direction, Y-axis direction, and Z-axis direction.

[0010] (Embodiment 1) Figure 1 shows a schematic configuration of the liquid injection device 1 of the present invention.

[0011] As shown in the figure, the liquid injection device 1 includes a liquid injection head 2, conveys the medium S in the X-axis direction, and reciprocates the liquid injection head 2 in the Y-axis direction, while printing is performed by injecting liquid in the +Z direction from the liquid injection head 2 toward the medium S. That is, it is a so-called serial printer. As the medium S, in addition to recording paper, any material such as a resin film or cloth can be used.

[0012] The liquid injection device 1 includes a liquid injection head 2, a liquid storage unit 3, a control unit 4, a conveyance mechanism 5 for feeding out the medium S, and a moving mechanism 6.

[0013] The liquid injection head 2 injects ink, which is an example of the liquid supplied from the liquid storage unit 3, as ink droplets in the +Z direction.

[0014] The liquid storage unit 3 stores the ink injected from the liquid injection head 2. Examples of the liquid storage unit 3 include a cartridge detachable from the liquid injection device 1, a bag-shaped ink pack formed of a flexible film, an ink tank capable of refilling ink, etc. Although not particularly shown in the figure, for example, a plurality of types of ink with different colors, components, etc. are individually stored in the liquid storage unit 3. Also, the liquid storage unit 3 may be divided into a main tank and a sub-tank. A configuration where the sub-tank is connected to the liquid injection head 2 and the consumed ink is replenished from the main tank to the sub-tank by injecting ink from the liquid injection head 2 may also be used. Also, the ink may be circulated between the liquid storage unit 3 and the liquid injection head 2.

[0015] The control unit 4 includes, for example, a control device such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array), and a storage device such as semiconductor memory. The control unit 4 also includes a power supply device that supplies power from an external power source such as a commercial power supply to each element of the liquid injection device 1. The control unit 4 is electrically connected to the liquid injection head 2 via external wiring (not shown). The control unit 4 comprehensively controls each element of the liquid injection device 1 by having the control device execute a program stored in the storage device.

[0016] The transport mechanism 5 transports the medium S in the X-axis direction and includes, for example, a transport roller 5a that is rotated by a transport motor controlled and driven by a control unit 4.

[0017] The moving mechanism 6 is a mechanism for reciprocating the liquid injection head 2 in the Y-axis direction, and comprises a holder 6a, which is a carriage that holds the liquid injection head 2, and a conveyor belt 6b, which is an endless belt that is installed along the Y-axis direction. The control unit 4 controls the drive of a conveyor motor (not shown) to rotate the conveyor belt 6b, thereby moving the liquid injection head 2 back and forth in the Y-axis direction together with the holder 6a fixed to the conveyor belt 6b.

[0018] The liquid spray head 2, under the control of the control unit 4, performs a spraying operation in which it ejects ink supplied from the liquid reservoir 3 as ink droplets in the +Z direction from each of the multiple nozzles 21 (see Figure 4). This spraying operation by the liquid spray head 2 is performed in parallel with the transport of the medium S by the transport mechanism 5 and the reciprocating movement of the liquid spray head 2 by the moving mechanism 6, thereby coating the medium S with ink, or printing, is performed.

[0019] Figure 2 is a block diagram of the liquid injection device 1. As shown in Figure 2, the liquid injection device 1 comprises a control unit 4, a transport mechanism 5, a moving mechanism 6, and a liquid injection head 2. The control unit 4 includes a control unit 120, a storage unit 121, and a drive signal generation circuit 122. The liquid injection head 2 includes a drive signal selection circuit 111, a plurality of piezoelectric actuators 300, a pressure acquisition unit 72, a detection circuit 71, and a strain gauge 70.

[0020] The control unit 120 includes one or more processing circuits, such as a CPU or FPGA. The control unit 120 generates signals to control the operation of each part of the liquid ejection device 1. The control unit 120 controls the ink ejection operation by the liquid ejection head 2.

[0021] The control unit 120 generates a print signal SI, a waveform specification signal dCom, and a timing signal PTS. The print signal SI is a digital signal that specifies the type of operation of the liquid spray head 2. The print signal SI specifies whether or not to supply a drive signal Com to the piezoelectric actuator 300. The waveform specification signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the piezoelectric actuator 300. The timing signal PTS is a signal that defines the generation timing of the drive signal Com.

[0022] The storage unit 121 includes one or more storage circuits such as semiconductor memory. The storage unit 121 stores print data Img supplied from the host computer. The storage unit 121 stores the control program for the liquid injection device 1.

[0023] The drive signal generation circuit 122 includes a DA conversion circuit. The drive signal generation circuit 122 generates a drive signal Com having a waveform defined by the waveform specification signal dCom. The drive signal generation circuit 122 outputs the drive signal Com each time it receives the timing signal PTS.

[0024] The drive signal selection circuit 111 switches whether or not to supply the drive signal Com to each piezoelectric actuator 300 based on the print signal SI. The drive signal selection circuit 111 selects the piezoelectric actuator 300 to which the drive signal Com is supplied based on the print signal SI, latch signal LAT, and change signal CH supplied from the control unit 4. The latch signal LAT defines the latch timing of the print data Img. The change signal CH defines the selection timing of the drive pulse included in the drive signal Com.

[0025] The pressure acquisition unit 72 acquires the pressures of the first liquid chamber 81 and the second liquid chamber 82, which will be described later, based on the resistance value of the strain gauge 70 of the detection circuit 71.

[0026] Figure 3 is an exploded perspective view of the liquid injection head. Figure 4 is a cross-sectional view of the liquid injection head. The directions of the liquid injection head 2 will be described based on the directions in which the liquid injection head 2 is mounted on the liquid injection device 1, i.e., the X-axis direction, Y-axis direction, and Z-axis direction. The liquid injection head 2 of this embodiment comprises a plurality of head chips Hc, a flow path member 200, a relay substrate 210, and a cover head 220.

[0027] The flow path member 200 comprises a first flow path member 201 provided with a first flow path 401, a second flow path member 202 provided with a second flow path 402, and a sealing member 203 that connects the first flow path 401 and the second flow path 402 in a liquid-tight manner. The first flow path member 201, the sealing member 203, and the second flow path member 202 are stacked in this order in the +Z direction.

[0028] In this embodiment, the first flow channel member 201 is constructed by stacking three members in the Z-axis direction. The first flow channel member 201 has a connection portion 204 that is connected to a liquid storage section 3 in which liquid is stored. In this embodiment, the connection portion 204 is provided on the -Z-direction surface of the first flow channel member 201, protruding cylindrically in the -Z direction. The liquid storage section 3 may be directly connected to this connection portion 204, or it may be connected via a supply pipe such as a tube. Inside this connection portion 204, a first flow channel 401 is provided through which liquid from the liquid storage section 3 is supplied. The first flow channel 401 is composed of a flow channel extending in the Z-axis direction, a flow channel extending along the stacking interface of the stacked members, etc. In addition, a liquid reservoir section 401a is provided in the middle of the first flow channel 401, which has a wider inner diameter than other sections, and a filter 401b is provided inside the liquid reservoir section 401a. Furthermore, in this embodiment, one first flow channel member 201 comprises eight connection portions 204 and eight independent first flow channels 401.

[0029] The second flow channel member 202 has a plurality of second flow channels 402 that communicate with each of the ends of the plurality of first flow channels 401 opposite to the connection portion 204. In other words, in this embodiment, one second flow channel member 202 comprises eight independent second flow channels 402. The first flow channels 401 and the second flow channels 402 are liquid-tightly connected via a sealing member 203. The sealing member 203 can be made of a material that is liquid-resistant to the liquid used in the liquid injection head 2 and is elastically deformable, such as rubber or elastomer. Such a sealing member 203 is provided with a connecting flow channel 403 that penetrates in the Z-axis direction, and the first flow channels 401 and the second flow channels 402 communicate via the connecting flow channel 403. In other words, the flow channel member 200 is provided with eight independent flow channels 400, each comprising a first flow channel 401, a second flow channel 402, and a connecting flow channel 403.

[0030] Multiple head tips Hc are held on the surface of the second flow channel member 202 facing the +Z direction. Specifically, the second flow channel member 202 has a housing portion 208 having a concave shape that opens on the surface facing the +Z direction, and the head tips Hc are housed in this housing portion 208. The liquid injection head 2 of this embodiment holds multiple head tips Hc, in this embodiment, as an example, four head tips Hc. In this embodiment, the four head tips Hc are arranged side by side in the Y-axis direction so that they are in the same position with respect to the X-axis direction.

[0031] In this embodiment, a configuration in which one housing section 208 is provided in common for all head chips Hc is illustrated, but the invention is not limited to this. For example, the housing section 208 may be provided independently for each head chip Hc, or independently for each group of two or more head chips Hc.

[0032] A second flow path 402 is connected to each inlet 44 of the head tip Hc.

[0033] The second flow channel member 202 is provided with wiring insertion holes 205 for inserting the wiring members 110 of each head chip Hc. In this embodiment, one wiring insertion hole 205 is provided for each head chip Hc. In other words, in this embodiment, a total of four wiring insertion holes 205 are provided for four head chips Hc. The wiring members 110 of the head chip Hc are led out through the wiring insertion holes 205 to the side of the second flow channel member 202 facing the -Z direction.

[0034] Furthermore, in the Z-axis direction, a relay board 210 is provided between the second flow channel member 202 and the sealing member 203, to which the wiring members 110 of multiple head chips Hc are commonly connected. The relay board 210 is made of a rigid, inflexible substrate and has wiring and electronic components (not shown) mounted on it. In this embodiment, a connector 211 (not shown) to which external wiring provided outside the liquid spray head 2 is connected is shown as an electronic component. Print signals for controlling the head chips Hc are input from the external wiring to the relay board 210 via the connector 211, and supplied from the relay board 210 to each head chip Hc. An external wiring opening 206 is provided on the side wall of the flow channel member 200 facing the connector 211 for inserting the external wiring connected to the connector 211. The external wiring is connected to the connector 211 of the relay board 210 provided inside the flow channel member 200 via the external wiring opening 206.

[0035] The relay board 210 is provided with wiring insertion holes 212 for leading the wiring members 110 of the head chip Hc to the side facing the -Z direction. There is one wiring insertion hole 212 for each head chip Hc, for a total of four holes.

[0036] Furthermore, the relay substrate 210 is provided with a projection insertion hole 213 that penetrates in the Z-axis direction. On the surface of the second flow channel member 202 facing the -Z direction, a projection 207 is provided that has a second flow channel 402 inside and protrudes toward the -Z direction. The projection 207 is inserted through the projection insertion hole 213 into the -Z side of the relay substrate 210 and connected to the connecting flow channel 403.

[0037] A cover head 220 is fixed to the surface of the flow channel member 200 facing the +Z direction. The cover head 220 defines the space of the housing portion 208 that houses the head chip Hc. In this embodiment, the cover head 220 is large enough to cover four head chips Hc. The cover head 220 is a common member fixed to the surface of the four head chips Hc facing the +Z direction. In addition, the cover head 220 is independently provided with an exposure opening 221 for each head chip Hc that exposes the nozzle 21 of the head chip Hc toward the +Z direction. Ink is ejected toward the +Z direction from the nozzle 21 exposed through the exposure opening 221.

[0038] The head chip Hc will be explained using Figures 5 to 10. Figure 5 is an exploded perspective view of the head chip Hc. Figure 6 is a plan view of the head chip Hc. Figure 7 is a cross-sectional view taken along line A-A' in Figure 6. Figure 8 is a cross-sectional view taken along line B-B' in Figure 6. Figure 9 is a plan view showing the flow path of the head chip Hc. Figure 10 is a diagram showing an example of a strain gauge and pressure detection unit. Note that in Figure 6, the protective substrate 30, case member 40, communication plate 15, and compliance substrate 45 of the head chip Hc are omitted from the diagram. The line A-A' is parallel to the Y-axis direction and passes through the nozzle 21 that discharges liquid and the pressure chamber 12 that communicates with it. The line B-B' is parallel to the Y-axis direction and passes through the strain gauge 70 and the corresponding first liquid chamber 81. Furthermore, in Figure 9, for the sake of simplification, the first individual flow path 131 including the first liquid chamber 81 and the first individual flow path 131 including the second liquid chamber 82 are represented as one each, and the second individual flow path 132 including the pressure chamber 12 is represented as six.

[0039] The head chip Hc comprises a nozzle plate 20 on which a plurality of nozzles 21 are formed, a flow path forming substrate 10, a communication plate 15, a protective substrate 30, a case member 40, a piezoelectric actuator 300, and a wiring member 110.

[0040] The channel-forming substrate 10 is made of, for example, a silicon substrate. Multiple pressure chambers 12 are arranged in a line along the X-axis direction on the channel-forming substrate 10. The multiple pressure chambers 12 are arranged on a straight line along the X-axis direction so that they are in the same position with respect to the Y-axis direction. Two adjacent pressure chambers 12 in the X-axis direction are separated by a partition wall (not shown). In this embodiment, two rows of pressure chambers 12, arranged in a line along the X-axis direction, are provided in the Y-axis direction. These two rows of pressure chambers are arranged with a half-pitch offset from each other in the X-axis direction. In other words, all the pressure chambers 12 in the two rows of pressure chambers are arranged in a staggered pattern along the X-axis direction.

[0041] Of the multiple pressure chambers 12, the one located at the -X end in the X-axis direction is referred to as the first pressure chamber 12A. In the head tip Hc of this embodiment, there are two rows of pressure chambers 12 arranged in parallel in the X-axis direction, so there are two first pressure chambers 12A. Of the multiple pressure chambers 12, the one located at the +X end in the other X-axis direction is referred to as the second pressure chamber 12B. There are also two second pressure chambers 12B, similar to the first pressure chambers 12A.

[0042] On the surface of the channel-forming substrate 10 facing the +Z direction, a communication plate 15 and a nozzle plate 20 are sequentially laminated. On the surface of the channel-forming substrate 10 facing the -Z direction, a diaphragm 50 and a piezoelectric actuator 300 are sequentially laminated.

[0043] The communication plate 15 consists of a plate-shaped member joined to the surface of the flow path forming substrate 10 facing the +Z direction. The communication plate 15 is provided with a nozzle communication passage 16 that connects the pressure chamber 12 and the nozzle 21. The communication plate 15 is also provided with a first manifold section 17 and a second manifold section 18, which constitute part of the manifold 100 that forms a common liquid chamber through which multiple pressure chambers 12 communicate. The first manifold section 17 is provided penetrating the communication plate 15 in the Z-axis direction. The second manifold section 18 is provided opening to the surface facing the +Z direction without penetrating the communication plate 15 in the Z-axis direction. Furthermore, the communication plate 15 is provided with a supply communication passage 19 that communicates with each of the pressure chambers 12 independently. The supply communication passage 19 connects the second manifold section 18 and the pressure chamber 12, supplying ink from the manifold 100 to the pressure chamber 12. Such a connecting plate 15 can be a silicon substrate, a glass substrate, an SOI substrate, various ceramic substrates, a metal substrate such as a stainless steel substrate, or the like.

[0044] The nozzle plate 20 is joined to the side of the communication plate 15 opposite to the flow path forming substrate 10, that is, the side facing the +Z direction. Multiple nozzles 21 are formed on the nozzle plate 20, communicating with each pressure chamber 12 via nozzle communication passages 16. In this embodiment, the multiple nozzles 21 are arranged in a line along the X-axis direction. In this embodiment, two rows of nozzle rows L, in which the nozzles 21 are arranged side by side along the X-axis direction, are provided separated in the Y-axis direction. In this embodiment, the two rows of nozzle rows L are referred to as nozzle row La and nozzle row Lb in the +Y direction. Hereafter, when nozzle rows La and Lb are not distinguished, they will be referred to as nozzle row L. These nozzle rows La and Lb are arranged in the X-axis direction with a difference of half the pitch of the nozzles 21 from each other, so to speak, half a pitch. In other words, all the nozzles 21 in nozzle rows La and Lb are arranged in a staggered pattern along the X-axis direction.

[0045] Such nozzle plates 20 can include silicon substrates, glass substrates, SOI substrates, various ceramic substrates, metal substrates such as stainless steel substrates, and organic materials such as polyimide resin.

[0046] In this embodiment, the diaphragm 50 has an elastic film 51 made of silicon oxide provided on the channel-forming substrate 10 side, and an insulating film 52 made of zirconium oxide provided on the surface of the elastic film 51 facing the -Z direction. The diaphragm 50 may consist only of the elastic film 51, or only of the insulating film 52, or it may have other films in addition to the elastic film 51 and the insulating film 52.

[0047] The piezoelectric actuator 300 comprises a first electrode 60, a piezoelectric layer 61, and a second electrode 62 sequentially stacked on the diaphragm 50 in the -Z direction. Such a piezoelectric actuator 300 is also called a piezoelectric element, and refers to the portion including the first electrode 60, the piezoelectric layer 61, and the second electrode 62. Furthermore, the portion in the piezoelectric layer 61 where piezoelectric strain occurs when a voltage is applied between the first electrode 60 and the second electrode 62 is called the active portion 310. That is, the active portion 310 refers to the portion of the piezoelectric layer 61 sandwiched between the first electrode 60 and the second electrode 62. In this embodiment, an active portion 310 is formed for each pressure chamber 12. These multiple active portions 310 act as "driving elements" that cause pressure changes in the ink within the pressure chamber 12. Generally, one electrode of the active portion 310 is configured as an individual electrode independent of each active portion 310, and the other electrode is configured as a common electrode common to multiple active portions 310. In this embodiment, the first electrode 60 is divided into individual electrodes for each active portion 310, and the second electrode 62 is continuously provided across multiple active portions 310 to form a common electrode for multiple active portions 310. Of course, the first electrode 60 may constitute a common electrode and the second electrode 62 may constitute individual electrodes.

[0048] The piezoelectric layer 61 is constructed using a piezoelectric material consisting of a composite oxide with a perovskite structure represented by the general formula ABO3, for example.

[0049] Individual lead electrodes 91, which are lead wires, are drawn out from the first electrode 60. A common lead electrode 92, which is also a lead wire, is drawn out from the second electrode 62. A wiring member 110 made of a flexible substrate is connected to the ends of these individual lead electrodes 91 and common lead electrode 92 that are not connected to the piezoelectric actuator 300. The wiring member 110 is equipped with a drive signal selection circuit 111 which has multiple switching elements that select whether or not to supply a drive signal Com to each active part 310 in order to drive each of the active parts 310. In other words, the wiring member 110 in this embodiment is a COF (Chip On Film). Note that the wiring member 110 does not necessarily have to be provided with the drive signal selection circuit 111. In other words, the wiring member 110 may be an FFC (Flexible Flat Cable), an FPC (Flexible Printed Circuits), etc.

[0050] A protective substrate 30, having approximately the same size as the channel-forming substrate 10, is bonded to the surface of the channel-forming substrate 10 facing the -Z direction. The protective substrate 30 has a housing portion 31, which is a space for protecting the piezoelectric actuator 300. The housing portion 31 is provided independently for each row of piezoelectric actuators 300 arranged in the X-axis direction, and two of them are formed side by side in the Y-axis direction. The protective substrate 30 also has a through hole 32 that penetrates in the Z-axis direction between the two housing portions 31 arranged side by side in the Y-axis direction. The ends of the individual lead electrodes 91 and common lead electrodes 92 drawn from the electrodes of the piezoelectric actuator 300 extend so as to be exposed in this through hole 32, and the individual lead electrodes 91 and common lead electrodes 92 and the wiring member 110 are electrically connected in the through hole 32. Such a protective substrate 30 can be made of, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates, similar to the channel-forming substrate 10.

[0051] A case member 40 is fixed to the protective substrate 30, defining a manifold 100 that communicates with multiple pressure chambers 12 together with the flow path forming substrate 10. The case member 40 has substantially the same shape as the communication plate 15 described above in plan view, and is joined to the protective substrate 30 and also to the communication plate 15. This case member 40 has a recess 41 on the protective substrate 30 side that is deep enough to accommodate the flow path forming substrate 10 and the protective substrate 30. The case member 40 is also provided with a third manifold portion 42 that communicates with the first manifold portion 17 of the communication plate 15.

[0052] The manifold 100 of this embodiment is composed of a first manifold section 17 and a second manifold section 18 provided on the communication plate 15, and a third manifold section 42 provided on the case member 40. The manifold 100 is an example of a first common liquid chamber that is commonly connected to a plurality of pressure chambers 12 and the first liquid chamber 81 and second liquid chamber 82, which will be described later. In the plan view in the +Z direction shown in Figure 9, the manifold 100 is formed such that its width in the Y-axis direction narrows as it moves toward the +X and -X directions.

[0053] Furthermore, there are two manifolds 100, one for each nozzle row La and Lb. This allows different liquids to be sprayed from nozzle rows La and Lb. The case member 40 is also provided with an inlet 44 that communicates with the manifolds 100 and supplies ink to each manifold 100. The case member 40 is also provided with a connection port 40a through which a wiring member 110 is inserted, communicating with a through hole 32 in the protective substrate 30. The wiring member 110 is led out through the connection port 40a to the side of the liquid spray head 2 facing the -Z direction. The case member 40 can be made of metal, resin, or the like.

[0054] As shown in Figure 9, in the +Z direction, the inlet 44 is located between the first pressure chamber 12A and the second pressure chamber 12B in the X-axis direction. In this embodiment, the inlet 44 is located in the middle of the manifold 100 in the X-axis direction. The middle of the manifold 100 refers to any position in the second part when the manifold 100 is divided into three equal parts in the X-axis direction, and these parts are designated as the first part, second part, and third part from the -X direction to the +X direction.

[0055] Furthermore, a compliance substrate 45 is provided on the +Z-direction side of the communication plate 15 where the first manifold portion 17 and the second manifold portion 18 are open. This compliance substrate 45 seals the openings on the +Z-direction side of the first manifold portion 17 and the second manifold portion 18. In this embodiment, such a compliance substrate 45 comprises a sealing film 46 made of a flexible thin film and a fixed substrate 47 made of a hard material such as metal. The region of the fixed substrate 47 facing the manifold 100 is an opening 48 that has been completely removed in the thickness direction, so that one side of the manifold 100 becomes a compliance portion 49 which is a flexible portion sealed only by the flexible sealing film 46. The surface of the fixed substrate 47 facing the +Z direction is fixed to the surface of the cover head 220 facing the -Z direction with an adhesive or the like.

[0056] In this type of head chip Hc, liquid is drawn in through the inlet 44 and the flow path is filled with ink from the manifold 100 to the nozzle 21. Then, according to the signal from the drive signal selection circuit 111, a voltage is applied to each active part 310 corresponding to the pressure chamber 12, causing the diaphragm 50 to bend and deform together with the piezoelectric actuator 300. As a result, the pressure of the liquid in the pressure chamber 12 increases and droplets are ejected from the predetermined nozzle 21.

[0057] Furthermore, as shown in Figures 6, 8, and 9, the head tip Hc has a first liquid chamber 81, a second liquid chamber 82, and strain gauges 70 provided in the first liquid chamber 81 and the second liquid chamber 82, respectively.

[0058] Specifically, the first liquid chamber 81 and the second liquid chamber 82 are formed in the flow path forming substrate 10. The first liquid chamber 81 is positioned in the -X direction relative to the first pressure chamber 12A, which is located at the -X end of the plurality of pressure chambers 12. The second liquid chamber 82 is positioned in the +X direction relative to the second pressure chamber 12B, which is located at the +X end of the plurality of pressure chambers 12. In this embodiment, since there are two rows of the plurality of pressure chambers 12 arranged in parallel in the X-axis direction, there are two first liquid chambers 81 and two second liquid chambers 82.

[0059] The first liquid chamber 81 is positioned in the -X direction from the first pressure chamber 12A at the same distance as the distance between the pressure chambers 12 in the X-axis direction, and is formed so that its shape in a plan view in the +Z direction, as shown in Figure 6, is approximately the same as that of the pressure chamber 12. However, the first liquid chamber 81 does not necessarily have to be spaced at the same distance as the distance between the pressure chambers 12 in the X-axis direction. Furthermore, the supply passage 19 of the communication plate 15 is connected to the first liquid chamber 81, and the first liquid chamber 81 and the manifold 100 are in communication via the supply passage 19.

[0060] The second liquid chamber 82 is positioned in the +X direction from the second pressure chamber 12B at the same distance as the distance between the pressure chambers 12 in the X-axis direction, and is formed so that its shape in a plan view in the +Z direction, as shown in Figure 6, is approximately the same as that of the pressure chamber 12. However, the second liquid chamber 82 does not necessarily have to be spaced at the same distance as the distance between the pressure chambers 12 in the X-axis direction. The second liquid chamber 82, like the first liquid chamber 81, is connected to the manifold 100 via the supply passage 19. In this embodiment, the first liquid chamber 81 and the second liquid chamber 82 are not connected to the nozzle passage 16 and are not connected to the nozzle 21 that sprays liquid.

[0061] In this manner, a first individual flow path 131 and a second individual flow path 132 are formed from the flow paths formed in the flow path forming substrate 10 and the communication plate 15. The first individual flow path 131 is connected to the manifold 100 and includes a first liquid chamber 81. In this embodiment, the first individual flow path 131 consists of a second manifold section 18, a supply communication passage 19, and a first liquid chamber 81. Furthermore, a second liquid chamber 82, located on the opposite side of the first liquid chamber 81 in the X-axis direction, also constitutes the first individual flow path. That is, a flow path connected to the manifold 100 and including a second manifold section 18, a supply communication passage 19, and a second liquid chamber 82 is also the first individual flow path 131.

[0062] The second individual flow path 132 is connected to the manifold 100, communicates with each of the multiple nozzles 21, and includes each of the multiple pressure chambers 12. In this embodiment, the second individual flow path 132 consists of a second manifold section 18, a supply communication passage 19, a pressure chamber 12, and a nozzle communication passage 16.

[0063] In this embodiment, in a plan view in the +Z direction as shown in Figure 9, the width of the first individual channel 131 in the Y-axis direction is equal to the width of the second individual channel 132 in the Y-axis direction. Of course, the widths of the first individual channel 131 and the second individual channel 132 do not have to be the same in the Y-axis direction.

[0064] Furthermore, both the first individual flow path 131 and the second individual flow path 132 are narrowed in the portion connected to the manifold 100. Specifically, as shown in Figure 9, the second manifold section 18 consists of a narrowed section 18a connected to the manifold 100 with a constant width in the X-axis direction, a gradually increasing section 18b from the narrowed section 18a toward the supply passage 19 with a gradually increasing width in the X-axis direction, and a constant width section 18c from the gradually increasing section 18b toward the supply passage 19 with a constant width in the X-axis direction. The width of the narrowed section 18a in the X-axis direction is narrower than the width of the constant width section 18c in the X-axis direction.

[0065] As described above, both the first individual flow path 131 and the second individual flow path 132 have a throttling portion 18a in which the width of the flow path in the X-axis direction is narrowed, but the configuration is not limited to this. For example, it is preferable not to provide a throttling portion 18a in the first individual flow path 131 which includes the first liquid chamber 81. In other words, it is preferable that the first individual flow path 131 is formed with a constant width in the X-axis direction. Since the width of the first liquid chamber 81 is not narrowed by the throttling portion 18a, the accuracy of detecting the pressure in the first liquid chamber 81 can be improved.

[0066] The first liquid chamber 81 and the second liquid chamber 82 are defined by the diaphragm 50 at the -Z-direction opening of a through hole formed in the flow path forming substrate 10 that penetrates in the Z-axis direction. In other words, the first liquid chamber 81 and the second liquid chamber 82 are partially defined by the diaphragm 50. The part of the diaphragm 50 that defines the plane in the +Z direction, which is part of the first liquid chamber 81, is referred to as the first diaphragm 50A. The part of the diaphragm 50 that defines the plane in the +Z direction, which is part of the second liquid chamber 82, is referred to as the second diaphragm 50B.

[0067] In this embodiment, as shown in Figure 6, the width W1 in the X-axis direction of the first diaphragm 50A is greater than the width W2 in the X-axis direction of the diaphragm 50 that defines the plane in the +Z direction which is part of the first pressure chamber 12A. Similarly, for the second diaphragm 50B, the width W3 in the X-axis direction is greater than the width W4 in the X-axis direction of the diaphragm 50 that defines the plane in the +Z direction which is part of the second pressure chamber 12B.

[0068] Furthermore, although the first diaphragm 50A has a rectangular shape when viewed in the +Z direction as shown in Figure 6, it is not limited to this shape. For example, it may be a parallelogram, a so-called rounded rectangle (also known as a track shape) with semicircular ends on both sides of the length, or a polygon. In addition, the aspect ratio of the rectangle in which the first diaphragm 50A is inscribed is preferably between 0.8 and 1.2.

[0069] A strain gauge 70 is provided on the first diaphragm 50A on the side opposite to the first liquid chamber 81. The strain gauge 70 is made of metal, polycrystalline silicon, or semiconductor silicon. Examples of metals include NiCr, Pt, CuNi, and CrN. In this embodiment, the strain gauge 70 is formed by repeatedly extending and folding the metal in the X-axis direction. However, the method of forming the strain gauge 70 is not limited to extending and folding the metal in the X-axis direction. The strain gauge 70 is provided corresponding to the first diaphragm 50A that defines the first liquid chamber 81, but not corresponding to each pressure chamber 12. A strain gauge 70 is also provided on the second diaphragm 50B on the side opposite to the second liquid chamber 82.

[0070] The pressure in the first liquid chamber 81 and the second liquid chamber 82 is detected by utilizing the characteristic that the electrical resistance of metals, semiconductors, etc., changes when strain occurs. The pressure in the first liquid chamber 81 and the second liquid chamber 82 is the pressure exerted by the liquid filling the first liquid chamber 81 and the second liquid chamber 82 on the first diaphragm 50A and the second diaphragm 50B. This pressure can be considered to be the same as the pressure of the meniscus formed in the nozzle 21. When an external force is applied to the strain gauge 70 via the first diaphragm 50A and the second diaphragm 50B in response to the pressure in the first liquid chamber 81 and the second liquid chamber 82, a stress corresponding to this external force is applied to the strain gauge 70. As a result, strain occurs in the strain gauge 70 and its resistance value changes. By using this resistance value, the pressure in the first liquid chamber 81 and the second liquid chamber 82 can be detected.

[0071] By detecting the pressure in the first liquid chamber 81 using the strain gauge 70 in this way, the pressure in the first liquid chamber 81 can be obtained even when the liquid pressure does not change. Examples of situations where the liquid pressure does not change include when the liquid is only circulating and not being ejected from the nozzle 21, or when there is no flow in the liquid. Even in such cases where no liquid is being ejected, the pressure value of the first liquid chamber 81 can be measured. As a method of detecting the pressure in the first liquid chamber 81 without using the strain gauge 70, for example, residual vibrations that occur after liquid is ejected can be detected via the piezoelectric actuator 300, and the liquid pressure can be measured based on the signal of these residual vibrations. However, with this method, the change in liquid pressure can only be obtained at the moment the piezoelectric element deforms.

[0072] The strain gauge 70 is formed on the first diaphragm 50A, but the configuration is not limited to this. For example, other layers may be laminated on top of the diaphragm 50, and the strain gauge 70 may be formed on those layers. In other words, the first diaphragm refers to a structure composed of layers that function as a diaphragm, and specifically, it may consist of only the diaphragm 50, or it may include the diaphragm 50 and a first electrode 60 laminated on top of it, or it may include a piezoelectric layer 61, or it may include a second electrode 62. When a strain gauge is provided on the first diaphragm including the first electrode 60, the piezoelectric layer 61, and the second electrode 62, it should be electrically insulated.

[0073] Furthermore, although an example configuration has been given in which only a strain gauge 70 is provided on the first diaphragm 50A, the configuration is not limited to this. For example, a piezoelectric actuator 300 may be formed on a part of the first diaphragm 50A, and a strain gauge 70 may be provided on the other part.

[0074] Furthermore, the diaphragm 50 corresponding to the first pressure chamber 12A and the first diaphragm 50A are not separate but formed from a single continuous component. Similarly, the second diaphragm 50B is also formed from a single continuous component with the diaphragm 50. In this way, the first diaphragm 50A and the second diaphragm 50B are formed from the same component as the diaphragm 50 on which the piezoelectric actuator 300 acts. This allows the first diaphragm 50A and the second diaphragm 50B to be manufactured using the same process as the diaphragm 50 on which the piezoelectric actuator 300 acts, thereby reducing costs. Of course, the first diaphragm 50A and the second diaphragm 50B and the diaphragm 50 on which the piezoelectric actuator 300 acts may be manufactured as separate components. Also, the first diaphragm 50A may be made thinner or made from a more easily deformable material than the diaphragm 50 on which the piezoelectric actuator 300 acts. This makes the first diaphragm 50A more easily deformable, allowing for more accurate detection of the pressure in the first liquid chamber 81.

[0075] Specifically, the head chip Hc is provided with a detection circuit 71 that acquires the output voltage based on the resistance value of the strain gauge 70. An example of the detection circuit 71 is shown in Figure 10.

[0076] The detection circuit 71 includes, in addition to the strain gauge 70, a first resistive element 75, a second resistive element 76, and a third resistive element 77. The strain gauge 70, the first resistive element 75, the second resistive element 76, and the third resistive element 77 constitute a Wheatstone bridge circuit. One end of the strain gauge 70 is connected to the first resistive element 75, and the other end is connected to the third resistive element 77. The first resistive element 75 is connected to the second resistive element 76, and the second resistive element 76 is connected to the third resistive element 77. The detection circuit 71 is connected to a power supply (not shown) that applies voltage to points In1 and In2. When a change occurs in the resistance value of the strain gauge 70, a voltage difference is generated between points Out1 and Out2.

[0077] In the example shown in Figure 10, one detection circuit 71 is configured for each strain gauge 70. As shown in Figure 6, four strain gauges 70 are provided on the head tip Hc, so four detection circuits 71 are also provided. Thus, a detection circuit 71 may be provided for each strain gauge 70, or one detection circuit 71 may be shared among multiple strain gauges 70. For example, the strain gauges 70 corresponding to the first diaphragm 50A and the second diaphragm 50B may be connected to a single detection circuit 71. In this case, the strain gauges 70 can be connected in place of the second resistive element 76 shown in Figure 10.

[0078] It is preferable that the first to third resistive elements 75 to 77 are located in the same temperature environment as the strain gauge 70, in a location where no pressure is applied, and that their resistance values ​​are the same when no pressure is applied to the strain gauge 70 and the first to third resistive elements 75 to 77. For this reason, it is preferable that the first to third resistive elements 75 to 77 are adjacent to the strain gauge 70 in the -X direction, located in the first liquid chamber 81, and are provided on the same diaphragm 50 as the strain gauge 70, with the same pattern as the strain gauge 70. Forming them on the same diaphragm 50 with the same pattern reduces the difference in manufacturing variations between the first to third resistive elements 75 to 77 and the strain gauge 70.

[0079] The In1, In2, Out1, and Out2 points of the detection circuit 71 are electrically connected to the wiring member 110 (see Figure 6). The wiring member 110 is provided with a pressure acquisition unit 72. The pressure acquisition unit 72 realizes the function of acquiring the pressure of the first liquid chamber 81 and the second liquid chamber based on the resistance value of the strain gauge 70, and in this embodiment it is implemented as an electronic circuit provided on the wiring member 110. The pressure acquisition unit 72 acquires the output voltage e of the detection circuit 71 and determines the strain of the strain gauge 70. The relationship between the output voltage e, the strain, and the pressures of the first liquid chamber 81 and the second liquid chamber 82 is stored in advance in the storage unit 121. Therefore, the pressures of the first liquid chamber 81 and the second liquid chamber 82 can be determined based on the output voltage e based on the resistance value.

[0080] The liquid injection head 2 described above comprises a plurality of nozzles 21 for injecting liquid, a plurality of pressure chambers 12 arranged in the X-axis direction to which pressure is applied to the liquid for injection from each of the plurality of nozzles 21, a first liquid chamber 81 positioned in the -X direction relative to a first pressure chamber 12A located at the -X end of the plurality of pressure chambers 12, a first diaphragm 50A defining a part of the first liquid chamber 81, and a manifold 100 commonly connected to the plurality of pressure chambers 12 and the first liquid chamber 81, and has a strain gauge 70 for obtaining the pressure in the first liquid chamber 81 corresponding to the first diaphragm 50A.

[0081] In such a liquid injection head 2, if the pressure of the liquid filling all the nozzles 21 decreases due to, for example, clogging of the filter 401b, the liquid near the first pressure chamber 12A, located at one end in the X-axis direction which is the direction in which the nozzles 21 are arranged side by side, will experience a particularly large pressure loss, and there is a high risk that the meniscus formed in the nozzle 21 will be destroyed. This is because, as shown in Figure 9, the first pressure chamber 12A is farther from the inlet 44, and therefore has a relatively larger pressure loss than the liquid near the other pressure chambers 12. Furthermore, in this embodiment, the width of the manifold 100 in the Y-axis direction narrows as it moves from the inlet 44 toward the +X and -X directions, so the first pressure chamber 12A has a relatively larger pressure loss than the liquid near the other pressure chambers 12.

[0082] If the pressure near the first pressure chamber 12A, which is located at the -X end of the multiple pressure chambers 12, is appropriate, then there is no need to measure the pressure in the other pressure chambers 12, as they will have a higher pressure. In other words, in order to prevent meniscus failure in all nozzles 21, it is sufficient to measure the pressure near the first pressure chamber 12A, which has a particularly large pressure loss, and it is not necessary to measure the pressure near the other pressure chambers 12.

[0083] In this embodiment, the liquid injection head 2 only needs to measure the pressure in the first liquid chamber 81, which has a particularly large pressure loss, as described above. Therefore, a strain gauge 70 is provided corresponding to the first liquid chamber 81. This prevents meniscus damage in all nozzles 21 without increasing the cost or size of the liquid injection head 2, compared to a configuration in which a strain gauge 70 is provided individually in all pressure chambers 12 to measure the pressure. Specifically, a pressure threshold is set within a range smaller than the meniscus pressure withstand capability. If the pressure value detected based on the resistance value of the strain gauge 70 exceeds the threshold, a warning is issued prompting abnormality detection or replacement of the head or filter, thereby preventing meniscus damage. This prevents the inability to spray liquid normally and prevents air bubbles from entering the nozzle, thus preventing the inability to spray normally due to meniscus damage. Alternatively, a pressure threshold is set within a range larger than the meniscus pressure withstand capability. If the detected pressure value exceeds the threshold, a warning is issued prompting abnormality detection of the self-sealing valve, thereby preventing meniscus damage. This also helps to prevent the meniscus from being destroyed, which would then prevent the normal ejection of liquid.

[0084] Note that "-X direction" corresponds to "first direction". "Strain gauge 70" corresponds to "first detection element". "Manifold 100" corresponds to "first common liquid chamber". "First detection element corresponding to the first diaphragm" refers to the strain gauge 70 that is provided in contact with the surface of the first diaphragm 50A opposite to the surface defining the first liquid chamber 81. Also, when viewed in the +Z direction, which is the direction of liquid injection, the strain gauge 70, the first liquid chamber 81, and the first diaphragm 50A overlap. In this way, the first detection element is provided to correspond to the first diaphragm and is therefore not in contact with the liquid. For this reason, the first detection element is not limited to having liquid resistance.

[0085] For example, the first detection element is not limited to the strain gauge 70, but can also be a piezoelectric element or a capacitive sensor. When a piezoelectric element is used as the first detection element, the pressure in the first liquid chamber 81 can be detected as follows.

[0086] A piezoelectric element is provided on the first diaphragm 50A as a first detection element. The configuration of the piezoelectric element is the same as that of the piezoelectric actuator 300, so a detailed explanation is omitted. Capacitance is obtained based on the voltage applied to the piezoelectric element on the first diaphragm 50A, and the pressure in the first liquid chamber 81 is detected based on that capacitance.

[0087] The capacitance changes in response to the pressure in the first liquid chamber 81. Specifically, when the pressure in the first liquid chamber 81 changes, the first diaphragm 50A deforms in accordance with that pressure change. When the first diaphragm 50A deforms, stress is applied to the piezoelectric element provided on the first diaphragm 50A. This stress on the piezoelectric element changes its polarization state. This change in polarization state manifests as a change in the dielectric constant of the piezoelectric element, resulting in a change in capacitance. Therefore, the capacitance changes in response to the change in pressure in the first liquid chamber 81.

[0088] Since there is a correlation between the capacitance of the piezoelectric element and the pressure in the first liquid chamber 81, the pressure in the first liquid chamber 81 can be detected based on the capacitance by using the piezoelectric element. The aforementioned pressure acquisition unit 72 then acquires the capacitance of the piezoelectric element based on the voltage applied to the piezoelectric element and acquires the pressure in the first liquid chamber 81 based on the capacitance. In this way, the pressure in the first liquid chamber 81 can be detected based on the capacitance by using the piezoelectric element as the first detection element and the pressure acquisition unit 72.

[0089] When a capacitive sensor is used as the first detection element, the pressure in the first liquid chamber 81 can be detected as follows. A capacitive sensor is provided as the first detection element corresponding to the first diaphragm 50A. The capacitive sensor has a movable electrode and a fixed electrode. The movable electrode is provided on the side of the first diaphragm 50A opposite to the second liquid chamber 82 side, and the fixed electrode is provided on the +Z direction surface of the protective substrate 30 at a position opposite to the movable electrode. The first diaphragm 50A deforms in response to the pressure in the first liquid chamber 81, and the position of the movable electrode changes with the deformation of the first diaphragm 50A. On the other hand, the position of the fixed electrode does not change, so the distance in the Z-axis direction between the movable electrode and the fixed electrode changes in response to the pressure in the first liquid chamber 81. As the distance between the movable electrode and the fixed electrode changes, the capacitance between the movable electrode and the fixed electrode changes. Therefore, the capacitance changes in response to the change in pressure in the first liquid chamber 81. Thus, the pressure in the first liquid chamber 81 can be detected based on the capacitance obtained by the capacitive sensor, similar to the case of a piezoelectric element.

[0090] The liquid injection head 2 of this embodiment has a pressure acquisition unit 72 that acquires the pressure in the first liquid chamber 81 based on the resistance value of the strain gauge 70.

[0091] The liquid injection head 2 of this embodiment further has an inlet 44 for introducing liquid into the manifold 100. The plurality of pressure chambers 12 have a second pressure chamber 12B located at the end in the +X direction, which is the opposite direction to the -X direction. When viewed in the +Z direction from which the plurality of nozzles 21 spray liquid, the inlet 44 is positioned between the first pressure chamber 12A and the second pressure chamber 12B in the -X direction. In such a liquid injection head 2, compared to the case where the inlet 44 is positioned outside the pressure chambers 12 in the X-axis direction, neither the first pressure chamber 12A nor the second pressure chamber 12B is significantly further from the inlet 44 than the other. In other words, the pressure loss in the first pressure chamber 12A and the second pressure chamber 12B at both ends is about the same, and it is possible to eliminate a pressure chamber 12 with a significantly large pressure loss. Note that "+X direction" corresponds to "second direction". "+Z direction" corresponds to "injection direction".

[0092] The liquid injection head 2 of this embodiment further includes a second liquid chamber 82 positioned in the +X direction relative to the second pressure chamber 12B located at the +X end, which is opposite to the -X direction of the multiple pressure chambers 12, and connected to the manifold 100; a second diaphragm 50B defining a part of the second liquid chamber 82; and a strain gauge 70 corresponding to the second diaphragm 50B for obtaining the pressure in the second liquid chamber 82. Such a liquid injection head 2 can detect pressure in the first liquid chamber 81 and the second liquid chamber 82. For example, if a single detection circuit 71 is provided for the strain gauge 70 as shown in Figure 10, abnormalities in the meniscus at both ends of the nozzle 21 can be detected individually. Also, if the strain gauge 70 corresponding to the first diaphragm 50A and the strain gauge 70 corresponding to the second diaphragm 50B are connected to a common detection circuit 71, the average of the pressure values ​​of the nozzles 21 at both ends can be detected. Furthermore, the "strain gauge 70 for obtaining the pressure in the second liquid chamber 82, corresponding to the second diaphragm 50B" corresponds to the "second detection element."

[0093] The liquid injection head 2 of this embodiment does not have a piezoelectric actuator 300 corresponding to the first liquid chamber 81, but has multiple piezoelectric actuators 300 that apply pressure to multiple pressure chambers 12. That is, only a strain gauge 70 is provided in the first liquid chamber 81, and no piezoelectric actuator 300 is provided. With such a liquid injection head 2, the first diaphragm 50A is not obstructed by the piezoelectric actuator 300, so it can be made more easily deformable. Since the first diaphragm 50A is easily deformed by the liquid pressure, the pressure in the first liquid chamber 81 can be detected with greater accuracy.

[0094] In this embodiment, the liquid injection head 2 has a width W1 in the -X direction of the first diaphragm 50A that is greater than the width W2 in the -X direction of the diaphragm 50 that defines a portion of the first pressure chamber 12A.

[0095] The liquid injection head 2 of this embodiment includes a plurality of individual flow paths connected to the manifold 100. Each of the plurality of individual flow paths communicates with a plurality of nozzles 21 and has a plurality of second individual flow paths 132, each containing a plurality of pressure chambers 12, and a first individual flow path 131 containing a first liquid chamber 81. The width of the first individual flow path 131 in the Y-axis direction, which intersects the -X direction and the +Z direction, which is the injection direction for spraying liquid, is equal to the width of the second individual flow path 132 in the Y-axis direction. Note that "Y-axis direction" corresponds to "third direction". In this embodiment, the widths of the first individual flow path 131 and the second individual flow path 132 in the Y-axis direction are equal, but they may be different.

[0096] (Modification 1 of Embodiment 1) Figure 11 shows Modification 1 of Embodiment 1. The liquid injection head 2 according to Modification 1 differs from the liquid injection head 2 according to Embodiment 1 in that the first liquid chamber 81 is in communication with the dummy nozzle 21D, and a piezoelectric actuator 300 is formed on the first diaphragm 50A in addition to the strain gauge 70. In Modification 1, the first liquid chamber 81 is referred to as the first dummy liquid chamber 81D.

[0097] Specifically, the first dummy liquid chamber 81D has a strain gauge 70 provided on a portion of the first diaphragm 50A that defines the first dummy liquid chamber 81D, and a piezoelectric actuator 300 formed on the other portion. The strain gauge 70 is not limited to being provided on the first diaphragm 50A, and may, for example, be stacked in the +Z direction of the piezoelectric actuator 300.

[0098] Furthermore, the first dummy liquid chamber 81D, like the pressure chamber 12 shown in Figure 7, is connected to a nozzle communication passage 16 formed in the communication plate 15. The nozzle communication passage 16 is connected to a dummy nozzle 21D formed in the nozzle plate 20. The dummy nozzle 21D is a nozzle that does not contribute to printing. Not contributing to printing means that it sprays liquid as a flushing agent to prevent viscosity buildup, but does not spray droplets to directly form an image on the medium.

[0099] The liquid spray head 2 according to this modified example 1 provides the same effects as in Embodiment 1. Furthermore, since the first dummy liquid chamber 81D is connected to the dummy nozzle 21D which does not contribute to printing, the liquid is easily filled into the flow path from the manifold 100 to the supply passage 19, the first dummy liquid chamber 81D, the nozzle passage 16, and the dummy nozzle 21D. Because the liquid filling properties into the flow path are good in this way, for example, when performing an initial filling process to fill the flow path when it is not filled with liquid, the liquid can be filled well into the first dummy liquid chamber 81D and the dummy nozzle 21D without leaving any air bubbles.

[0100] Furthermore, in the liquid injection head 2 having the first dummy liquid chamber 81D, it is preferable to employ a first individual flow path 131 having a throttling portion 18a as shown in Figure 9. This is because the flushing described above can be performed effectively.

[0101] In Embodiment 1, the first liquid chamber 81 is not connected to a nozzle 21 that does not contribute to printing. However, as in Modification 1, it is preferable to provide a dummy nozzle 21D and a piezoelectric actuator 300 in the first dummy liquid chamber 81D. It is also preferable to periodically clean and flush the dummy nozzle 21D, just like the other nozzles 21. This prevents the liquid in the first dummy liquid chamber 81D from becoming thicker.

[0102] (Modification 2 of Embodiment 1) Figure 12 shows a modified example 2 of Embodiment 1. The liquid injection head 2 according to Modified Example 2 differs from the liquid injection head 2 according to Embodiment 1 in that a strain gauge 70 is provided on one end in the X-axis direction, and the position of the inlet 44 is different.

[0103] Specifically, the strain gauge 70 is positioned to correspond to the first diaphragm 50A (see Figure 6) that defines the first liquid chamber 81. Furthermore, the distance from the inlet 44 to the first pressure chamber 12A is greater than the distance from the inlet 44 to the second pressure chamber 12B. The distance from the inlet 44 to the first pressure chamber 12A refers to the shortest distance of the flow path between the inlet 44 and the first pressure chamber 12A. The same applies to the distance from the inlet 44 to the second pressure chamber 12B.

[0104] In this modified example 2 of the liquid injection head 2, where the strain gauge 70 is located in one place, it is placed in the first liquid chamber 81, which is located at the end furthest from the inlet 44. Since the pressure loss increases with distance from the inlet 44, the pressure in the first liquid chamber 81, which is at a position with greater pressure loss, can be detected. Furthermore, since there is only one strain gauge 70, the cost of the liquid injection head 2 can be reduced and its size can be miniaturized compared to a configuration in which strain gauges 70 are provided at both ends in the X-axis direction.

[0105] In Figure 12, the inlet 44 is positioned inward from the multiple pressure chambers 12 in the X-axis direction. That is, the position of the inlet 44 in the X-axis direction is on the +X side of the first pressure chamber 12A at the -X end, and on the -X side of the second pressure chamber 12B at the +X end. The inlet 44 is not limited to this arrangement and may be positioned outward from the multiple pressure chambers 12 in the X-axis direction. That is, the position of the inlet 44 in the X-axis direction may be on the -X side of the first pressure chamber 12A, or on the +X side of the second pressure chamber 12B.

[0106] (Modification 3 of Embodiment 1) Figure 13 shows a third modification of Embodiment 1. The liquid injection head 2 according to the third modification differs from the liquid injection head 2 according to Embodiment 1 in that two strain gauges 70 are provided on the first diaphragm 50A, and the two strain gauges 70 are connected to a single detection circuit 71.

[0107] Specifically, the liquid injection head 2 corresponds to the first diaphragm 50A (see Figure 6) and has strain gauges 70A and 70B for obtaining the pressure in the first liquid chamber 81 (see Figure 6). When strain gauges 70A and 70B show the same resistance change, that is, when both strain gauges 70A and 70B are positioned to be tensile or compressed, the detection circuit 71 connects strain gauge 70A to the first resistive element 75 and the third resistive element 77, and connects strain gauge 70B to the first resistive element 75 and the third resistive element 77 instead of the second resistive element 76. These strain gauges 70A, 70B, the first resistive element 75, and the third resistive element 77 constitute a Wheatstone bridge circuit. Furthermore, if strain gauges 70A and 70B exhibit different resistance changes, that is, if one strain gauge 70A is being stretched and the other is being compressed, strain gauge 70B and the first resistive element 75 are swapped. In other words, strain gauge 70A is connected to the third resistive element 77 and strain gauge 70B, and strain gauge 70B is connected to the first resistive element 75 and strain gauge 70A.

[0108] As shown in the liquid spray head 2 of this modified example 3, one detection circuit 71 has two strain gauges 70 provided on one first diaphragm 50A. A pressure acquisition unit 72 that acquires the pressure of the first liquid chamber 81 based on the resistance values ​​obtained by such a detection circuit 71 with two strain gauges 70 has improved detection accuracy of the pressure in the first liquid chamber 81 compared to a pressure acquisition unit 72 that acquires the pressure of the first liquid chamber 81 based on the resistance value of a detection circuit 71 with one strain gauge 70. Note that "strain gauge 70A" corresponds to the "first detection element" and "strain gauge 70B" corresponds to the "second detection element".

[0109] Although not specifically shown in the figures, four strain gauges 70 may be provided on the first diaphragm 50A. Then, the first resistive element 75 and the third resistive element 77 shown in Figure 13 are replaced with the strain gauges 70. That is, a Wheatstone bridge circuit may be formed using the four strain gauges 70, and this may be used as the detection circuit 71. By configuring the detection circuit 71 with four strain gauges 70 on the first diaphragm 50A in this way, the pressure in the first liquid chamber 81 can be detected with even greater accuracy.

[0110] (Modification 4 of Embodiment 1) In Embodiment 1, as shown in Figure 7, the head tip Hc is provided with two rows of nozzles, La and Lb, arranged side by side in the X-axis direction, and two manifolds 100 are provided corresponding to them. As shown in Figure 6, a total of four strain gauges 70 are provided, one on the -X side of the first pressure chamber 12A and one on the +X side of the second pressure chamber 12B, corresponding to each nozzle row La and Lb.

[0111] In Modification 4, although not specifically shown in the figures, the strain gauges 70 are arranged point-symmetrically in a plan view in the +Z direction as shown in Figure 6. For example, a strain gauge 70 is provided on the first diaphragm 50A that defines the first liquid chamber 81, which is located on the -X direction side of the first pressure chamber 12A on the -Y direction side. A strain gauge 70 is also provided on the second diaphragm 50B that defines the second liquid chamber 82, which is located on the +X direction side of the second pressure chamber 12B on the +Y direction side.

[0112] In the liquid spray head 2 according to this modified example 4, since strain gauges 70 are not provided on the first diaphragm 50A on the +Y direction side and the second diaphragm 50B on the -Y direction side, the wiring leading from the strain gauges 70 can be placed in these spaces, making wiring arrangement easier. Therefore, the size of the liquid spray head 2 can be reduced compared to the case where four strain gauges 70 are arranged as shown in Figure 6. In addition, when the liquid spray head 2 is in an orientation other than the +Z direction in which it sprays liquid, for example, in an orientation such as vertical printing, a pressure difference occurs between the first liquid chamber 81 and the second liquid chamber 82. This pressure difference can be obtained from the difference in pressure values ​​detected by two strain gauges 70 located on the +X direction side and the -X direction side, respectively. Since this pressure difference is a value corresponding to the angle between the direction in which the liquid spray head 2 sprays liquid and the horizontal plane, the angle (orientation) of the liquid spray head 2 can be detected based on the pressure difference.

[0113] (Modification 5 of Embodiment 1) In Modification 4, two strain gauges 70 are provided so as to be point-symmetrical when viewed in the +Z direction as shown in Figure 6, but in Modification 5, they are arranged so as to be symmetrical in the X-axis direction, which is the direction in which the pressure chambers 12 are aligned.

[0114] Specifically, although not shown in the figures, a strain gauge 70 is provided on the first diaphragm 50A that defines the first liquid chamber 81 which is located on the -X side of the first pressure chamber 12A on the -Y side. Furthermore, a strain gauge 70 is provided on the first diaphragm 50A that defines the first liquid chamber 81 which is located on the -X side of the first pressure chamber 12A on the +Y side. According to this modified example 5 of the liquid injection head 2, a strain gauge 70 is not provided on the second diaphragm 50B that defines the second liquid chamber 82, so the size of the head tip Hc in the X-axis direction can be reduced.

[0115] (Modification 6 of Embodiment 1) In Embodiment 1, the pressure acquisition unit 72 was provided on the wiring member 110 of the liquid injection head 2, but the configuration is not limited to this. Figure 14 is a block diagram of a liquid injection device 1 according to Modification 6. The liquid injection device 1 according to Modification 6 has a liquid injection head 2 and a pressure acquisition unit 72. The pressure acquisition unit 72 is provided on the liquid injection device 1, not the liquid injection head 2. For example, the pressure acquisition unit 72 is provided as part of the control unit 4 of the liquid injection device 1. In this case, the head chip Hc has a strain gauge 70 and a detection circuit 71, and the output voltage e detected by the detection circuit 71 is transmitted to the pressure acquisition unit 72 of the control unit 4 via the wiring member 110 or the relay board 210. Even with this configuration, the same effects and advantages as the liquid injection device 1 equipped with the liquid injection head 2 of Embodiment 1 are achieved.

[0116] (Embodiment 2) The present invention can also be applied to a so-called circulating type liquid injection head 2. Figure 15 is a plan view showing the flow path of the head tip according to Embodiment 2. Figure 16 is a cross-sectional view taken along line C-C' in Figure 15. Figure 17 is a cross-sectional view taken along line D-D' in Figure 15. In Figure 15, the diaphragm 50 and the piezoelectric actuator 300 are omitted from the illustration. The same reference numerals are used for components identical to those in Embodiment 1, and redundant explanations are omitted.

[0117] The head tip Hc is equipped with a first individual channel 131 and a second individual channel 132. In this embodiment, as shown in Figure 15, the first individual channel 131 and the second individual channel 132 extend in the Y-axis direction and are spaced apart in the X-axis direction.

[0118] The head tip Hc includes a supply-side manifold 100A for supplying liquid to multiple nozzles 21, and a recovery-side manifold 100B for recovering liquid that was not ejected from the multiple nozzles 21.

[0119] The head tip Hc is provided with an inlet 44 that communicates with the supply-side manifold 100A and an outlet 43 that communicates with the recovery-side manifold 100B. Liquid is introduced into the inlet 44 from the liquid storage unit 3 provided in the liquid injection device 1. The outlet 43 is connected to the liquid storage unit 3, and the liquid is recovered from the outlet 43 to the liquid storage unit 3.

[0120] Liquid is supplied to the supply-side manifold 100A of the head tip Hc from the inlet 44. The liquid in the supply-side manifold 100A is supplied to the first individual flow path 131 and the second individual flow path 132, and the liquid supplied to the second individual flow path 132 is ejected from each nozzle 21. Any liquid supplied to the second individual flow path 132 that is not ejected from the nozzle 21 is discharged to the recovery-side manifold 100B. On the other hand, the first individual flow path 131 is not provided with a nozzle 21. Therefore, the liquid flows through the supply-side manifold 100A, the first individual flow path 131, and the recovery-side manifold 100B in this order.

[0121] The configuration of the head chip Hc will be described in more detail. The flow path forming substrate 10 is provided with a plurality of pressure chambers 12R and pressure chambers 12L corresponding to each nozzle 21. The pressure chambers 12R and pressure chambers 12L are provided penetrating the flow path forming substrate 10 in the Z direction, which is the thickness direction. In this embodiment, one second individual flow path 132 includes one pressure chamber 12R and one pressure chamber 12L. Pressure chamber 12R is located closer to the supply-side manifold 100A, and pressure chamber 12L is located closer to the recovery-side manifold 100B.

[0122] A diaphragm 50 and a piezoelectric actuator 300 are formed on the -Z direction side of the flow path forming substrate 10. The piezoelectric actuator 300 is provided at positions on the diaphragm 50 corresponding to pressure chambers 12R and 12L.

[0123] The connecting plate 15 is provided with the following channels that constitute the second individual channel 132: the first connecting channel 33A, the first connecting channel 33B, the first connecting channel 33C, and the second connecting channel 34A, the second connecting channel 34B, the second connecting channel 34C, and the second connecting channel 34D. The first communication channel 33A opens on the +Z side of the communication plate 15 and extends in the Y-axis direction, with one end of it communicating with the supply-side manifold 100A. The first communication channel 33B opens on the +Z side of the communication plate 15, extends in the Y-axis direction, and communicates with the nozzle 21. The first communication channel 33C opens on the +Z side of the communication plate 15 and extends in the Y-axis direction, with one end communicating with the recovery side manifold 100B. The second communication channel 34A penetrates the communication plate 15 in the Z-axis direction and connects the first communication channel 33A and the pressure chamber 12R. The second communication channel 34B penetrates the communication plate 15 in the Z-axis direction and connects the pressure chamber 12R with the first communication channel 33B. The second communication channel 34C penetrates the communication plate 15 in the Z-axis direction and connects the first communication channel 33B and the pressure chamber 12L. The second communication channel 34D penetrates the communication plate 15 in the Z-axis direction and connects the pressure chamber 12L with the first communication channel 33C.

[0124] These first communication channels 33A, first communication channel 33B, first communication channel 33C, second communication channel 34A, second communication channel 34B, second communication channel 34C, and second communication channel 34D have openings on the +Z direction side sealed by a compliance substrate 45 to form a channel. Thus, the second individual channel 132 of this embodiment is composed of the first communication channel 33A, second communication channel 34A, pressure chamber 12R, second communication channel 34B, first communication channel 33B, second communication channel 34C, pressure chamber 12L, second communication channel 34D, and first communication channel 33C.

[0125] On the other hand, the first individual flow path 131 has a similar configuration to the second individual flow path 132, but differs from the second individual flow path 132 in that it does not communicate with the nozzle 21. Furthermore, the first individual flow path 131 differs from the second individual flow path 132 in that it has a first liquid chamber 81R and a first liquid chamber 81L instead of pressure chambers 12R and 12L. In other words, the first individual flow path 131 in this embodiment is composed of a first communication flow path 33A, a second communication flow path 34A, a first liquid chamber 81, a second communication flow path 34B, a first communication flow path 33B, a second communication flow path 34C, a first liquid chamber 81L, a second communication flow path 34D, and a first communication flow path 33C.

[0126] A strain gauge 70 is provided corresponding to the first diaphragm 50A that defines the first liquid chamber 81R. In this embodiment, a strain gauge 70 is not provided in the first liquid chamber 81L, but a strain gauge 70 may be provided corresponding to the first liquid chamber 81L. In addition, although not shown in the figures, a detection circuit is provided on the diaphragm 50, making it possible to detect the pressure in the first liquid chamber 81L in the same manner as in Embodiment 1.

[0127] The liquid injection head 2 according to Embodiment 2 described above comprises a plurality of second individual flow paths 132 through which liquid is supplied from the supply-side manifold 100A, each of which communicates with a plurality of nozzles 21 and includes each of the plurality of pressure chambers 12; a recovery-side manifold 100B for recovering liquid that was not injected from the plurality of nozzles 21 from the plurality of second individual flow paths 132; and a first individual flow path 131 which includes a first liquid chamber 81R and connects the supply-side manifold 100A and the recovery-side manifold 100B.

[0128] In such a liquid injection head 2, the pressure in the multiple pressure chambers 12 does not vary significantly whether the pressure chamber 12 is located at the end in the X-axis direction or at the center. Therefore, to prevent meniscus failure in all nozzles 21, the pressure can be measured near any of the pressure chambers 12. Accordingly, in this embodiment, the liquid injection head 2 is equipped with a strain gauge 70 only on the first diaphragm 50A that defines the first liquid chamber 81R, so as to measure only the pressure in the first liquid chamber 81R. This reduces the cost and size increase of the liquid injection head 2 compared to a configuration in which a strain gauge 70 is provided for each pressure chamber 12, and prevents meniscus failure in all nozzles 21.

[0129] Furthermore, among the multiple pressure chambers 12 arranged in parallel in the X-axis direction, a first liquid chamber 81R is provided on the -X side of the first pressure chamber 12A located at the end in the -X direction, and a strain gauge 70 is provided in the first liquid chamber 81. This allows the nozzles 21 that contribute to printing to be arranged at equal intervals and at high density compared to cases where the first liquid chamber 81R is provided at locations other than the ends, such as between adjacent first pressure chambers 12A in the X-axis direction.

[0130] Furthermore, in the liquid injection head 2 of this embodiment, since the liquid circulates, the viscosity of the liquid in the first liquid chamber 81R is prevented, and the pressure can be accurately detected.

[0131] Note that the "supply-side manifold 100A" corresponds to the "first common liquid chamber," and the "recovery-side manifold 100B" corresponds to the "second common liquid chamber." In addition, although the first individual flow path 131 does not have a nozzle 21, a dummy nozzle may be provided, similar to the modification 1 of Embodiment 1.

[0132] (Other embodiments) Although various embodiments of the present invention have been described above, the basic configuration of the present invention is not limited to those described above.

[0133] Furthermore, in the embodiments described above, a thin-film piezoelectric actuator 300, essentially an active part 310, was used as the driving element for generating a pressure change in the pressure chamber 12. However, the invention is not limited to this, and the driving element can be, for example, a thick-film piezoelectric actuator formed by attaching a green sheet, or a longitudinal vibration type piezoelectric actuator that expands and contracts in the axial direction by alternately stacking piezoelectric material and electrode forming material. In addition, the driving element can be a so-called electrostatic actuator in which a heating element is placed in the pressure chamber 12 and droplets are ejected from the nozzle 21 by bubbles generated by the heat generated by the heating element, or an electrostatic actuator that generates static electricity between a diaphragm and an electrode, deforming the diaphragm with electrostatic force and ejecting droplets from the nozzle 21.

[0134] Furthermore, although the liquid spraying device 1 described above is exemplified in which the liquid spraying head 2 moves in the main scanning direction, which is the Y-axis direction, the present invention is not limited to this, and can also be applied to so-called line-type printers in which the liquid spraying head 2 is fixed and printing is performed simply by moving the medium S in the sub-scanning direction, which is the X-axis direction.

[0135] Furthermore, the present invention broadly applies to liquid spraying devices equipped with spraying units. Examples of spraying units include recording heads such as various inkjet recording heads used in image recording devices such as printers, and colorant spraying heads used in the manufacture of color filters for liquid crystal displays. Other examples of spraying units include electrode material spraying heads used in electrode formation for organic EL displays and FEDs (field emission displays), and bio-organic material spraying heads used in biochip manufacturing, and the invention can also be applied to liquid spraying devices equipped with these spraying units.

[0136] (Note) From the forms exemplified above, the following configuration can be understood, for example.

[0137] A liquid spray head according to Embodiment 1, a preferred embodiment, comprises a plurality of nozzles for spraying liquid, a plurality of pressure chambers arranged in a first direction to which pressure for spraying liquid from each of the plurality of nozzles is applied to the liquid, a first liquid chamber positioned in the first direction relative to the first pressure chamber located at the first end of the plurality of pressure chambers in the first direction, a first diaphragm defining a part of the first liquid chamber, and a first common liquid chamber connected in common to the plurality of pressure chambers and the first liquid chamber, and has a first detection element corresponding to the first diaphragm for obtaining the pressure in the first liquid chamber. Compared to a configuration in which a first detection element is individually provided in each pressure chamber to measure the pressure, this prevents meniscus failure in all nozzles without increasing the cost or size of the liquid spray head. Specifically, before the meniscus is destroyed, if the pressure value detected based on the resistance value of the first detection element exceeds a set pressure threshold within a range smaller than the meniscus withstand pressure, an abnormality detection or a warning prompting replacement of the liquid spray head or filter is issued. This improves the quality of the liquid spray head. Specifically, by preventing the meniscus from being destroyed, it becomes possible to prevent the normal spraying of liquid from occurring, and by suppressing the entry of air bubbles into the nozzle, it becomes possible to prevent the spraying from being impaired.

[0138] In Embodiment 2, which is a specific example of Embodiment 1, there is a pressure acquisition unit that acquires the pressure of the first liquid chamber based on the resistance value of the first detection element. With this, the pressure of the first liquid chamber can be acquired even when the liquid pressure does not change. An example of when the liquid pressure does not change is when the liquid is only circulating and not being ejected from the nozzle. Even when no liquid is being ejected in such a case, the pressure value of the first liquid chamber can be measured.

[0139] In Embodiment 3, which is a specific example of Embodiment 1, the first liquid chamber is a first dummy liquid chamber that communicates with a dummy nozzle that does not contribute to printing. With this configuration, the liquid can be filled into the first dummy liquid chamber well. For example, when performing an initial filling process to fill the first dummy liquid chamber with liquid when it is not yet filled, the liquid can be filled into the first dummy liquid chamber and dummy nozzle well without leaving any air bubbles or the like.

[0140] In Embodiment 4, which is a specific example of Embodiment 1, the first common liquid chamber further has an inlet for introducing liquid, and the plurality of pressure chambers have a second pressure chamber located at the end of the second direction, which is the opposite direction to the first direction, and the distance from the inlet to the first pressure chamber is greater than the distance from the inlet to the second pressure chamber. According to this, when the first detection element is provided in one place on the liquid injection head, it is provided in the first liquid chamber located at the end furthest from the inlet. Since the pressure loss increases with distance from the inlet, the pressure in the first liquid chamber at a position with a greater pressure loss can be detected.

[0141] In Embodiment 5, which is a specific example of Embodiment 1, the first common liquid chamber further has an inlet for introducing liquid, and the plurality of pressure chambers have a second pressure chamber located at the end of the second direction, which is the opposite direction to the first direction, and the inlet is positioned between the first pressure chamber and the second pressure chamber in the first direction when viewed in the injection direction in which the plurality of nozzles spray liquid. With this, compared to the case in which the inlet is positioned outside the pressure chamber in the first direction, neither the first pressure chamber nor the second pressure chamber will be significantly farther from the inlet than the other. In other words, the pressure loss in the first and second pressure chambers at both ends will be about the same, and it will be possible to eliminate a pressure chamber with a significantly large pressure loss.

[0142] In embodiment 6, which is a specific example of embodiment 2, the pressure acquisition unit further includes a second detection element corresponding to the first diaphragm for acquiring the pressure in the first liquid chamber, and the pressure acquisition unit acquires the pressure in the first liquid chamber based on the resistance value of the second detection element as well. Since the pressure acquisition unit acquires the pressure in the first liquid chamber based on the first detection element and the second detection element, the detection accuracy of the pressure in the first liquid chamber can be improved compared to a pressure acquisition unit that acquires the pressure in the first liquid chamber based on the resistance value of a single first detection element.

[0143] In embodiment 7, which is a specific example of embodiment 1, the device further includes a second liquid chamber located at the end of the second direction, which is the opposite direction to the first direction of the plurality of pressure chambers, the second liquid chamber being arranged in the second direction and connected to the first common liquid chamber, a second diaphragm defining a part of the second liquid chamber, and a second detection element corresponding to the second diaphragm for acquiring the pressure in the second liquid chamber. With this, pressure can be detected in the first liquid chamber and the second liquid chamber.

[0144] In Embodiment 8, which is a specific example of Embodiment 1, there is no piezoelectric element corresponding to the first liquid chamber, but there are multiple piezoelectric elements that apply pressure to the multiple pressure chambers. With this configuration, the first diaphragm is not obstructed by the piezoelectric elements and can be easily deformed. Since the first diaphragm is easily deformed by the liquid pressure, the pressure in the first liquid chamber can be detected with greater accuracy.

[0145] In embodiment 9, which is a specific example of embodiment 1, the width of the first diaphragm in the first direction is greater than the width of the diaphragm in the first direction that defines a part of the first pressure chamber.

[0146] In embodiment 10, which is a specific example of embodiment 9, a plurality of individual flow paths are provided connected to the first common liquid chamber, and each of the plurality of individual flow paths communicates with each of the plurality of nozzles and has a plurality of second individual flow paths including each of the plurality of pressure chambers, and a first individual flow path including the first liquid chamber, and the width of the first individual flow path in a third direction intersecting the first direction and the injection direction for spraying liquid is equal to the width of the second individual flow path in the third direction.

[0147] In embodiment 11, which is a specific example of embodiment 1, a plurality of second individual channels to which liquid is supplied from the first common liquid chamber comprises a plurality of second individual channels communicating with each of the plurality of nozzles and including each of the plurality of pressure chambers, a second common liquid chamber for recovering liquid that was not ejected from the plurality of nozzles from the plurality of second individual channels, and a first individual channel including the first liquid chamber and connecting the first common liquid chamber and the second common liquid chamber. Compared to a configuration in which a first detection element is provided for each of the pressure chambers to measure the pressure, this configuration can suppress an increase in the cost and size of the liquid injection head and can prevent the destruction of the meniscus in all nozzles. Furthermore, by providing the first liquid chamber on the first direction side of the plurality of pressure chambers, rather than the first pressure chamber located at the end in the first direction, and providing the first detection element in that first liquid chamber, the nozzles contributing to printing can be arranged at equal intervals and at high density compared to the case in which they are provided elsewhere. Furthermore, in the liquid injection head, the liquid circulates from the first common liquid chamber through the first liquid chamber to the second common liquid chamber, which prevents the liquid in the first liquid chamber from becoming thicker and allows for accurate pressure detection.

[0148] A liquid injection device according to embodiment 12, which is a preferred embodiment, comprises a liquid injection head according to embodiment 1 and a pressure acquisition unit that acquires the pressure of the first liquid chamber based on the resistance value of the first detection element. The pressure acquisition unit can be provided in the liquid injection device instead of the liquid injection head. This makes it possible to simplify the structure of the liquid injection head. [Explanation of Symbols]

[0149] Hc...Head tip, 1...Liquid injection device, 2...Liquid injection head, 10...Flow path forming substrate, 12, 12L, 12R...Pressure chamber, 12A...First pressure chamber, 12B...Second pressure chamber, 15...Communicating plate, 20...Nozzle plate, 21...Nozzle, 21D...Dummy nozzle, 43...Outlet, 44...Inlet, 45...Compliance substrate, 50...Diaphragm, 50A...First diaphragm, 50B...Second diaphragm, 60...First electrode, 61...Piezoelectric layer, 62...Second electrode, 70, 70A, 70B...Strain gauge, 71...Detection circuit, 72...Pressure sensor 75…First resistive element, 76…Second resistive element, 77…Third resistive element, 81, 81L, 81R…First liquid chamber, 81D…First dummy liquid chamber, 82…Second liquid chamber, 91…Individual lead electrodes, 92…Common lead electrodes, 100…Manifold, 100A…Supply-side manifold, 100B…Recovery-side manifold, 110…Wiring member, 111…Drive signal selection circuit, 131…First individual flow path, 132…Second individual flow path, 200…Flow path member, 210…Intermediate board, 220…Cover head, 300…Piezoelectric actuator

Claims

1. Multiple nozzles for spraying liquid, Pressure is applied to the liquid from each of the aforementioned multiple nozzles, and a plurality of pressure chambers are arranged in a first direction, A first liquid chamber is positioned in the first direction relative to the first pressure chamber located at the first end of the plurality of pressure chambers, A first diaphragm that defines a part of the first liquid chamber, The system comprises a plurality of pressure chambers and a first common liquid chamber that is commonly connected to the first liquid chamber, It has a first detection element corresponding to the first diaphragm for obtaining the pressure inside the first liquid chamber, A liquid spray head characterized by the following features.

2. The unit includes a pressure acquisition unit that acquires the pressure of the first liquid chamber based on the resistance value of the first detection element. The liquid spray head according to feature 1.

3. The first liquid chamber is a first dummy liquid chamber that communicates with a dummy nozzle that does not contribute to printing. The liquid spray head according to feature 1.

4. The first common liquid chamber further has an inlet for introducing liquid, The plurality of pressure chambers each have a second pressure chamber located at the end of the second direction, which is the opposite direction to the first direction. The distance from the inlet to the first pressure chamber is greater than the distance from the inlet to the second pressure chamber. The liquid spray head according to feature 1.

5. The first common liquid chamber further has an inlet for introducing liquid, The plurality of pressure chambers each have a second pressure chamber located at the end of the second direction, which is the opposite direction to the first direction. In the direction in which the plurality of nozzles spray liquid, the inlet is positioned between the first pressure chamber and the second pressure chamber in the first direction. The liquid spray head according to feature 1.

6. The device further comprises a second detection element corresponding to the first diaphragm for obtaining the pressure in the first liquid chamber, The pressure acquisition unit also acquires the pressure of the first liquid chamber based on the resistance value of the second detection element. The liquid spray head according to feature 2.

7. A second liquid chamber is located at the end of the plurality of pressure chambers in the second direction, which is opposite to the first direction, and is arranged in the second direction and connected to the first common liquid chamber, A second diaphragm that defines a part of the second liquid chamber, The device further comprises a second detection element corresponding to the second diaphragm for obtaining the pressure in the second liquid chamber. The liquid spray head according to feature 1.

8. It does not have a piezoelectric element corresponding to the first liquid chamber, but has a plurality of piezoelectric elements that apply pressure to the plurality of pressure chambers. The liquid spray head according to feature 1.

9. The width of the first diaphragm in the first direction is greater than the width of the diaphragm in the first direction that defines a portion of the first pressure chamber. The liquid spray head according to feature 1.

10. The system comprises multiple individual flow channels connected to the first common liquid chamber, The aforementioned plurality of individual channels are A plurality of second individual flow paths are connected to each of the plurality of nozzles and include each of the plurality of pressure chambers, It has a first individual flow path including the first liquid chamber, The width of the first individual flow path in the third direction intersecting the first direction and the injection direction for spraying the liquid is equal to the width of the second individual flow path in the third direction. The liquid spray head according to feature 9.

11. A plurality of second individual flow channels from which liquid is supplied from the first common liquid chamber, each of which communicates with the plurality of nozzles and includes each of the plurality of pressure chambers, A second common liquid chamber for recovering liquid that was not ejected from the plurality of nozzles from the plurality of second individual flow paths, The system includes a first liquid chamber and a first individual flow path connecting the first common liquid chamber and the second common liquid chamber. The liquid spray head according to feature 1.

12. The liquid spray head according to claim 1, The pressure acquisition unit acquires the pressure of the first liquid chamber based on the resistance value of the first detection element. A liquid injection device characterized by the following features.

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