Control method, liquid dispensing device, and inkjet system

Abstract

To accurately determine whether or not an abnormality has occurred due to the medium colliding with the liquid dispensing head. [Solution] A control method for a liquid dispensing device that dispenses liquid onto a medium, comprising a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a liquid dispensing head having a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is discharged, includes an acquisition step of acquiring residual vibration information relating to residual vibration in the pressure chamber after applying a voltage to one or more of the plurality of piezoelectric elements, and a determination step of determining whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid dispensing head, based on the residual vibration information.

Description

Technical Field

[0001] The present invention relates to a control method, a liquid ejection device, and an inkjet system.

Background Art

[0002] Conventionally, a liquid ejection device having a liquid ejection head for ejecting a liquid onto a medium such as printing paper has been provided. In such a liquid ejection device, due to the liquid ejection head, such as thickening of the liquid in the liquid ejection head, ejection abnormalities may occur where the liquid cannot be normally ejected from the nozzles. For example, in Patent Document 1, based on the residual vibration that occurs after driving the liquid ejection head, there is a technique for determining the presence or absence of ejection abnormalities in the liquid ejection head, such as air bubbles being mixed into the liquid of the liquid ejection head, the liquid of the liquid ejection head thickening, and liquid leaking onto the nozzle surface of the liquid ejection head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described liquid ejection head, in addition to the mixing of air bubbles, thickening of the liquid, and leakage, ejection abnormalities may occur due to the medium colliding with the liquid ejection head. However, with the conventional technology, it has been difficult to determine whether an abnormality has occurred due to the medium colliding with the liquid ejection head.

Means for Solving the Problems

[0005] A control method according to one aspect of the present disclosure is a control method for a liquid dispensing device that dispenses liquid onto a medium, the device having a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a liquid dispensing head having a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is dispensed, the method comprising: an acquisition step of acquiring residual vibration information relating to residual vibration in the pressure chamber after applying a voltage to one or more of the plurality of piezoelectric elements; and a determination step of determining whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid dispensing head, based on the residual vibration information.

[0006] A liquid dispensing device according to one aspect of the present disclosure is a liquid dispensing device for dispensing liquid onto a medium, having a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a liquid dispensing head having a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is discharged, and comprising: an acquisition unit that acquires residual vibration information relating to residual vibration in the pressure chamber after a voltage is applied to one or more of the plurality of piezoelectric elements; and a determination unit that determines, based on the residual vibration information, whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid dispensing head.

[0007] An inkjet system according to one aspect of the present disclosure is an inkjet system comprising: a liquid ejection device that ejects liquid onto a medium, having a liquid ejection head having a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is ejected; and a server provided outside the liquid ejection device, wherein the liquid ejection device acquires residual vibration information relating to residual vibration in the pressure chamber after applying a voltage to one or more of the plurality of piezoelectric elements, transmits the residual vibration information from the liquid ejection device to the server, and the server determines, based on the residual vibration information, whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid ejection head. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic diagram showing an example configuration of the inkjet system 10 according to the first embodiment. [Figure 2] A diagram showing an example of the configuration of Server 300. [Figure 3] A diagram showing the configuration of the processing unit 200. [Figure 4] A schematic diagram illustrating an example of the configuration of inkjet printer 100. [Figure 5] A block diagram showing an example configuration of inkjet printer 100. [Figure 6] A cross-sectional view showing an example configuration of the head tip 111. [Figure 7] An enlarged cross-sectional view of the vicinity of the piezoelectric element 111f. [Figure 8] A block diagram showing an example of the configuration of a liquid dispensing head HU. [Figure 9] A diagram showing a timing chart to explain the operation of inkjet printer 100 during the recording period Tu. [Figure 10] A diagram illustrating the functions of the inkjet system 10. [Figure 11] A diagram showing a flowchart illustrating the operation of the inkjet system 10. [Figure 12] This diagram shows a flowchart illustrating the abnormality detection process for nozzle row La. [Figure 13] A diagram illustrating a method for determining whether residual vibration is abnormal or not. [Figure 14] A diagram showing a flowchart illustrating the operation of the inkjet system 10 in the second embodiment. [Figure 15] This diagram shows a flowchart illustrating the process for determining abnormalities in a medium collision between nozzle rows La. [Figure 16] This diagram shows a flowchart illustrating the process for determining previously identified head abnormalities in nozzle row La. [Figure 17] A diagram showing a flowchart illustrating the operation of the inkjet system 10 in the first modified example. [Figure 18] A diagram showing the functions of the inkjet printer 100D in the second modification.

Mode for Carrying Out the Invention

[0009] Hereinafter, embodiments for implementing the present disclosure will be described with reference to the drawings. However, in each figure, the dimensions and scales of each part are appropriately different from the actual ones. Further, the embodiments described below are preferred specific examples of the present disclosure, and thus various technically preferable limitations are imposed. However, the scope of the present disclosure is not limited to these embodiments unless there is a description specifically limiting the present disclosure in the following description.

[0010] 1. First Embodiment 1-1. Outline of Inkjet System 10 FIG. 1 is a schematic diagram showing a configuration example of an inkjet system 10 according to the first embodiment. The inkjet system 10 is a system that performs a recording process on a medium PP, which will be described later, by an inkjet method. In the example shown in FIG. 1, the inkjet system 10 includes inkjet printers 100_1 to 100_3, processing devices 200_1 to 200_3, and a server 300.

[0011] Here, inkjet printers 100_1 to 100_3 are devices provided by the manufacturer of inkjet printers 100_1 to 100_3. In the following description, inkjet printers 100_1 to 100_3 may be collectively referred to as inkjet printer 100 without distinction. Inkjet printer 100 is a liquid ejection device that ejects ink, which is an example of a liquid. The manufacturer of inkjet printer 100 is the company that manufactures inkjet printer 100. The manufacturer of inkjet printer 100 may be referred to as the "printer manufacturer". Each of inkjet printers 100_1 to 100_3 may be provided by the same printer manufacturer or by different printer manufacturers. However, the liquid ejection head HU incorporated into inkjet printers 100_1 to 100_3 is provided by the manufacturer of the liquid ejection head HU. The manufacturer of the liquid ejection head HU is the company that manufactures the liquid ejection head HU. Hereafter, the manufacturer of the liquid ejection head HU may be referred to as the "head manufacturer". The printer manufacturer receives a liquid ejection head HU from the head manufacturer and manufactures the inkjet printer 100 by incorporating the provided liquid ejection head HU into the inkjet printer 100. The inkjet printer 100 is an example of a "liquid ejection device".

[0012] FIG. 1 shows a user U_1 who uses an inkjet printer 100_1, a user U_2 who uses an inkjet printer 100_2, and a user U_3 who uses an inkjet printer 100_3. In the following description, each of the users U_1 to U_3 may be generically referred to as user U without distinction. User U is, for example, an operator belonging to a printer manufacturer when using the inkjet printer 100, and this operator is user U. Also, for example, when a third party who has received the inkjet printer 100 from a printer manufacturer uses the inkjet printer 100, this third party is user U. In the following description, a third party who has received the inkjet printer 100 from a printer manufacturer may be described as an "end user". For each integer i from 1 to 3, in addition to the inkjet printer 100_i, user U_i uses a processing device 200_i.

[0013] The inkjet printer 100_1 is communicably connected to the processing device 200_1. The inkjet printer 100_2 is communicably connected to the processing device 200_2. The inkjet printer 100_3 is communicably connected to the processing device 200_3. Thus, the inkjet printers 100_1 to 100_3 respectively correspond to the processing devices 200_1 to 200_3 and are communicably connected to the processing devices 200_1 to 200_3. In the following description, each of the processing devices 200_1 to 200_3 may be generically referred to as processing device 200 without distinction.

[0014] Also, in the following, for each integer i from 1 to 3, a recording system 20_i may be described. The recording system 20_i includes the inkjet printer 100_i and the processing device 200_i. In the following description, each of the recording systems 20_1 to 20_3 may be generically referred to as recording system 20 without distinction. It can also be said that the inkjet system 10 includes the recording systems 20_1 to 20_3 and the server 300.

[0015] The original text to be translated is as below which wraped by : In the example shown in Figure 1, the inkjet system 10 has three inkjet printers 100 and three processing units 200, but this number is not limited to these three; it may be one, two, or four or more. In other words, the number of sets of inkjet printers 100 and processing units 200 is not limited to three; it may be one, two, or four or more.

[0016] The inkjet printer 100 receives image data Img from the processing unit 200. The inkjet printer 100 forms an image on the medium PP based on the image data Img. Hereinafter, the process of forming an image on the medium PP by ejecting ink onto the medium PP may be referred to as "recording process".

[0017] The PP medium is not particularly limited as long as it is a medium that the inkjet printer 100 can print on, and can include, for example, various types of paper such as printing paper, various types of fabric, or various types of film.

[0018] The inkjet printer 100 has one liquid ejection head HU. In the following description, the liquid ejection head HU ejects ink from a nozzle Nz provided on the liquid ejection head HU. Hereafter, the elements constituting the inkjet printer 100, excluding the liquid ejection head HU, may be referred to as the "printer body".

[0019] In the example shown in Figure 1, the inkjet printer 100 has one liquid ejection head HU, but the number of liquid ejection heads HU is not limited to one; there may be two or more.

[0020] The processing unit 200 is a computer, such as a desktop or notebook computer. The processing unit 200 is connected to the server 300 via a network NW such as a LAN, WAN, or the Internet. LAN is an abbreviation for Local Area Network. WAN is an abbreviation for Wide Area Network.

[0021] Server 300 is a computer that functions as a cloud server CS, as described later. Server 300 is managed by a different business operator than, for example, the head manufacturer, the printer manufacturer, and the end user. Hereafter, the business operator that manages Server 300 may be referred to as the "server operator." The head manufacturer uses a portion of Server 300.

[0022] 1-2. Server 300 Configuration Figure 2 shows an example of the configuration of server 300. Server 300 includes a control circuit 310, a memory circuit 320, and a communication device 380. The control circuit 310, the memory circuit 320, and the communication device 380 are interconnected by a bus 390 for communicating information.

[0023] The control circuit 310 includes, for example, one or more processors such as CPUs. CPU is an abbreviation for Central Processing Unit. The control circuit 310 may also include a programmable logic device such as an FPGA in place of, or in addition to, a CPU. FPGA is an abbreviation for Field Programmable Gate Array.

[0024] The memory circuit 320 is composed of a magnetic memory device or flash ROM, etc. The memory circuit 320 is readable by the control circuit 310 and stores multiple programs, including the virtualization program VM and control program PM1 executed by the control circuit 310, as well as various information used by the control circuit 310. The virtualization program VM divides the resources of the server 300, such as the control circuit 310 and the memory circuit 320, into multiple parts, and operates each of the divided resources as a cloud server CS. The headmaker uses some of the multiple cloud servers CS as part of the server 300. The control program PM1 is developed by the headmaker.

[0025] However, the memory circuit 320 does not need to have a virtualization program VM, and the processing unit 200 may access the server 300 instead of the cloud server CS.

[0026] The memory circuit 320 includes, for example, one or more volatile memories such as RAM and one or more non-volatile memories such as ROM, EEPROM, or PROM, or both, as semiconductor memory. RAM is an abbreviation for Random Access Memory. ROM is an abbreviation for Read Only Memory. EEPROM is an abbreviation for Electrically Erasable Programmable Read-Only Memory. PROM is an abbreviation for Programmable ROM.

[0027] The communication device 380 is hardware having a communication circuit for communicating with the processing unit 200 via a network NW. The communication device 380 may also be referred to as a network device, network controller, network card, or communication module, for example.

[0028] 1-3. Configuration of the processing unit 200 Figure 3 shows the configuration of the processing unit 200. The processing unit 200 includes a control circuit 210, a memory circuit 220, a communication device 230, an input device 260, and a display device 270. The control circuit 210, the memory circuit 220, the communication device 230, the input device 260, and the display device 270 are interconnected by a bus 290 for communicating information.

[0029] The control circuit 210 includes, for example, one or more processors such as CPUs. The control circuit 210 may also include a programmable logic device such as an FPGA in place of, or in addition to, a CPU.

[0030] The memory circuit 220 is composed of a magnetic memory device or flash ROM, etc. The memory circuit 220 is readable by the control circuit 210 and stores multiple programs, including the inkjet program PM2 executed by the control circuit 210, and various information used by the control circuit 210. The memory circuit 220 includes, for example, one or more volatile memories such as RAM and one or more non-volatile memories such as ROM, EEPROM, or PROM, or both, as semiconductor memory. The inkjet program PM2 is downloaded from the cloud server CS running on the server 300 and installed on the processing unit 200, for example, when the processing unit 200 is connected to the inkjet printer 100. The inkjet program PM2 is, for example, a program that generates image data Img. More specifically, the inkjet program PM2 generates image data Img that shows the image generated by the application program. The application program is, for example, an application program that creates documents and an application program that creates images.

[0031] The communication device 230 is hardware having a communication circuit for communicating with the processing unit 200 via a network NW. The communication device 230 may also be referred to as a network device, network controller, network card, or communication module, for example.

[0032] The communication device 240 is a circuit capable of communicating with the inkjet printer 100. For example, the communication device 240 is a network card such as USB or Bluetooth. USB is an abbreviation for Universal Serial Bus. USB and Bluetooth are registered trademarks.

[0033] The input device 260 is a device that outputs operation information in response to user U's actions. The input device 260 is, for example, a mouse and a keyboard.

[0034] The display device 270 displays an image containing some information to the user U. The display device 270 is an organic EL display, an LED display, or an LCD. EL is an abbreviation for Electro-Luminescence. LED is an abbreviation for Light Emitting Diode. LCD is an abbreviation for Liquid Crystal Display. Alternatively, the input device 260 and the display device 270 may be integrated into a single unit. An example of an integrated configuration of the input device 260 and the display device 270 is a touch panel.

[0035] As shown in Figures 1 to 3, there is a business model in which a head manufacturer provides a liquid ejection head HU to a printer manufacturer, and the printer manufacturer manufactures an inkjet printer 100 by incorporating the liquid ejection head HU into the printer body. In this business model, it is common for the printer manufacturer to design and manufacture everything except the liquid ejection head HU. In this embodiment, the head manufacturer provides a cloud server CS and an inkjet program PM2 that runs on the processing unit 200, and the user U connects the processing unit 200 to the cloud server CS and runs the inkjet program PM2 on the processing unit 200. As a result, in this embodiment, the printer manufacturer does not need to prepare the inkjet program PM2, thus reducing the design and manufacturing burden on the printer manufacturer.

[0036] 1-4. Configuration of the 100 Inkjet Printer Figure 4 is a schematic diagram illustrating an example of the configuration of the inkjet printer 100. Figure 5 is a block diagram illustrating an example of the configuration of the inkjet printer 100. In the following explanation, we assume mutually orthogonal X, Y, and Z axes. One direction along the X axis from any point is denoted as the X1 direction, and the opposite direction to the X1 direction is denoted as the X2 direction. Similarly, two opposite directions along the Y axis from any point are denoted as the Y1 and Y2 directions, and two opposite directions along the Z axis from any point are denoted as the Z1 and Z2 directions. The XY plane, which includes the X and Y axes, corresponds to the horizontal plane. The Z axis is an axis along the vertical direction, and the Z2 direction corresponds to the downward direction in the vertical direction.

[0037] The inkjet printer 100 according to the first embodiment is a serial printer that reciprocates the liquid ejection head HU along the X axis. Specifically, as shown in Figure 4, the inkjet printer 100 according to the first embodiment performs an ejection operation to form an image on the medium PP by transporting the medium PP in the Y1 direction, which is the sub-scanning direction, and moving the liquid ejection head HU in the X1 and X2 directions, which are the main scanning directions, while ejecting ink from the nozzles Nz. In Figure 4, some of the nozzles Nz of the liquid ejection head HU are typically shown.

[0038] As shown in Figure 4, the multiple nozzles Nz of the liquid discharge head HU are divided into nozzle rows La and nozzle row Lb, which are spaced apart from each other in the direction along the X axis. Each of nozzle row La and nozzle row Lb is a set of multiple nozzles Nz arranged linearly in the direction along the Y axis. In the following description, it is assumed that the number of nozzles Nz included in nozzle row La and nozzle row Lb is M, which is between 1 and 1. Therefore, the number of nozzles Nz that the liquid discharge head HU has is 2M. In order to distinguish each of the 2M nozzles Nz, the nozzles Nz in nozzle row La may be written as nozzle Nz[am1], and the nozzles Nz in nozzle row Lb may be written as nozzle Nz[bm2]. m1 and m2 are integers between 1 and M, inclusive. Also, in the following, nozzles Nz[a1] to nozzle Nz[aM] and nozzles Nz[b1] to nozzle Nz[bM] may be written as nozzle Nz without distinction. Furthermore, when specifying any one of the N nozzles Nz, it is sometimes written as nozzleNz[x], where x is one of the strings from a1 to aM, or from b1 to bM.

[0039] In this embodiment, as shown in Figure 4, among the M nozzles Nz divided into nozzle row La, the nozzle Nz furthest in the Y2 direction is denoted as nozzle Nz[a1], and the nozzle Nz furthest in the Y1 direction is denoted as nozzle Nz[aM]. Similarly, among the M nozzles Nz divided into nozzle row Lb, the nozzle Nz furthest in the Y2 direction is denoted as nozzle Nz[b1], and the nozzle Nz furthest in the Y1 direction is denoted as nozzle Nz[bM].

[0040] As shown in Figures 4 and 5, the inkjet printer 100 includes a control module CM, a liquid ejection head HU, a liquid container 120, a moving mechanism 130, a transport mechanism 140, a maintenance mechanism 145, a communication device 150, a memory circuit 160, and a control circuit 170.

[0041] The control module CM includes a power supply circuit 113 and a drive signal generation circuit 114. The liquid discharge head HU is an assembly that includes a head chip 111 and a drive circuit 112. The liquid discharge head HU may incorporate part or all of the control module CM.

[0042] The print head 111 ejects ink toward the PP medium. Figure 4 shows a representative example of the 2M piezoelectric elements 111f that make up the print head 111. A detailed example of the print head 111 will be explained later based on Figure 6.

[0043] In the example shown in Figure 5, the liquid discharge head HU has one head tip 111, but this number may be two or more. One or more head tips 111 are arranged so that multiple nozzles Nz are distributed across a portion of the width direction of the medium PP.

[0044] The drive circuit 112, under the control of the control circuit 170, switches whether or not to supply a drive signal Com output from the drive signal generation circuit 114 to each of the multiple piezoelectric elements 111f of the head chip 111.

[0045] The drive circuit 112 includes a switching circuit 115 and a detection circuit 117. The switching circuit 115, under the control of the control circuit 170, switches whether or not to supply a drive signal Com output from the drive signal generation circuit 114 to each of the 2M piezoelectric elements 111f on the head chip 111 connected to the drive circuit 112. The switching circuit 115 also switches whether or not to electrically connect each piezoelectric element 111f to the detection circuit 117. In this embodiment, it is assumed that the drive signal Com includes drive signal Com-A and drive signal Com-B. Furthermore, the signal actually supplied to the piezoelectric element 111f from drive signals Com-A and Com-B may be described as the supplied drive signal Vin. The switching circuit 115 includes, for example, a group of switches such as a transmission gate for the switching. Details of the switching circuit 115 will be described later with reference to Figure 7. The detection circuit 117 outputs a residual vibration signal NES, which indicates the vibration remaining in the pressure chamber CV (described later), to the generation circuit 190 after the piezoelectric element 111f has been driven. More specifically, the detection circuit 117 generates the residual vibration signal NES based on the detection signal Vout detected from the piezoelectric element 111f driven by the drive signal Com.

[0046] The power supply circuit 113 receives power from a commercial power source (not shown) and generates various predetermined potentials. The generated potentials are supplied to various parts of the inkjet printer 100 as appropriate. In the example shown in Figure 5, the power supply circuit 113 generates a power supply potential VHV and an offset potential VBS. The offset potential VBS is supplied to the head chip 111, etc. The power supply potential VHV is supplied to the drive signal generation circuit 114, etc.

[0047] The drive signal generation circuit 114 is a circuit that generates a drive signal Com for driving each piezoelectric element 111f of the head chip 111. Specifically, the drive signal generation circuit 114 includes, for example, a DA conversion circuit and an amplification circuit. In the drive signal generation circuit 114, the DA conversion circuit converts the waveform specification signal dCom from the control circuit 170 (described later) from a digital signal to an analog signal, and the amplification circuit generates the drive signal Com by amplifying the analog signal using the power supply potential VHV from the power supply circuit 113.

[0048] As illustrated in Figure 4, the inkjet printer 100 is equipped with a liquid container 120 for storing ink. For example, a cartridge that can be attached to the inkjet printer 100, a bag-shaped ink pack made of flexible film, or an ink tank that can be refilled with ink can be used as the liquid container 120.

[0049] The moving mechanism 130 and the transport mechanism 140 move the relative positions of the medium PP and the liquid discharge head HU under the control of the control circuit 170. Moving the relative positions means that the liquid discharge head HU may be moved while the position of the medium PP is fixed, or the medium PP may be moved while the position of the liquid discharge head HU is fixed. In this embodiment, with respect to the direction along the X-axis, which is the main scanning direction, the liquid discharge head HU is moved in the direction along the X-axis while the position of the medium PP in the X-axis is fixed, and with respect to the Y1 direction, which is the sub-scanning direction, the medium PP is moved in the Y1 direction while the position of the liquid discharge head HU in the direction along the Y-axis is fixed.

[0050] The moving mechanism 130 reciprocates the liquid discharge head HU along the X-axis under the control of the control circuit 170. As shown in Figure 4, the moving mechanism 130 comprises a roughly box-shaped carriage 131 that houses the liquid discharge head HU and an endless belt 132 to which the liquid discharge head HU is fixed. A configuration in which the liquid container 120 is mounted on the carriage 131 together with the liquid discharge head HU can also be adopted.

[0051] The transport mechanism 140 transports the medium PP in the Y1 direction under the control of the control circuit 170. Specifically, the transport mechanism 140 comprises a transport roller (not shown) whose rotation axis is parallel to the X axis, a motor (not shown) that rotates the transport roller under the control of the control circuit 170, and an encoder that outputs a signal to the control circuit 170 corresponding to the amount of rotation of the transport roller, and the transport position of the medium PP being transported in accordance with the rotation drive of the transport roller.

[0052] The communication device 150 is a circuit capable of communicating with the processing unit 200. For example, the communication device 150 is a network card such as a USB or Bluetooth card. Alternatively, the communication device 150 may be integrated with the control circuit 170.

[0053] The memory circuit 160 stores various programs, including the control program PM3 executed by the control circuit 170, and various data, such as image data Img, processed by the control circuit 170. The memory circuit 160 includes, for example, one or more volatile memories such as RAM and one or more non-volatile memories such as ROM, EEPROM, or PROM, or both, as semiconductor memory. The memory circuit 160 may be configured as part of the control circuit 170.

[0054] The control circuit 170 has the function of controlling the operation of each part of the inkjet printer 100 and the function of processing various data. The control circuit 170 includes, for example, one or more processors such as CPUs. The control circuit 170 may also include a programmable logic device such as an FPGA instead of a CPU, or in addition to a CPU.

[0055] The control circuit 170 controls the operation of each part of the inkjet printer 100 by executing a program stored in the memory circuit 160. Here, the control circuit 170 generates signals such as control signals Sk1, Sk2, Sk3, print signal SI, and waveform specification signal dCom as signals to control the operation of each part of the inkjet printer 100.

[0056] Control signal Sk1 is a signal for controlling the drive of the moving mechanism 130. Control signal Sk2 is a signal for controlling the drive of the transport mechanism 140. Control signal Sk3 is a signal for controlling the maintenance mechanism 145. Print signal SI is a signal for controlling the drive of the drive circuit 112. Specifically, print signal SI specifies at predetermined intervals whether or not the drive circuit 112 supplies the drive signal Com from the drive signal generation circuit 114 to the piezoelectric element 111f. This specification determines the amount of ink ejected from the head chip 111, etc. Waveform specification signal dCom is a digital signal for defining the waveform of the drive signal Com generated by the drive signal generation circuit 114.

[0057] When recording is performed, the control circuit 170 first stores the image data Img supplied from the processing unit 200 in the storage circuit 160. Next, the control circuit 170 generates various control signals such as the print signal SI, the waveform specification signal dCom, the control signal Sk1, the control signal Sk2, and the control signal Sk3 based on the image data Img stored in the storage circuit 160. Then, based on the various control signals and the various data stored in the storage circuit 160, the control circuit 170 controls the transport mechanism 140 and the moving mechanism 130 to change the relative position of the medium PP with respect to the liquid ejection head HU, while controlling the liquid ejection head HU so that the piezoelectric element 111f is driven. As a result, the control circuit 170 adjusts the presence or absence of ink ejection from the piezoelectric element 111f, the amount of ink ejected, and the timing of ink ejection, and controls the execution of the recording process to form an image on the medium PP based on the image data Img.

[0058] Furthermore, the inkjet printer 100 according to this embodiment may perform an ejection state determination process to determine whether the ink ejection state from each nozzle Nz is normal or defective. In addition, if an ejection defect occurs in a nozzle Nz included in the liquid ejection head HU, it may be described as an ejection defect of the liquid ejection head HU. Furthermore, a nozzle Nz that has experienced an ejection defect may be described as "defective nozzle Nz-T". On the other hand, a nozzle Nz that does not experience an ejection defect may be described as "normal ejection nozzle Nz-S".

[0059] Here, a discharge failure refers to a state in which, even when the piezoelectric element 111f is driven by the drive signal Com to attempt to discharge ink from the nozzle Nz, the ink cannot be discharged in the manner specified by the drive signal Com, resulting in a decrease in the discharge characteristics of the nozzle Nz. Discharge characteristics include, for example, the discharge volume and / or discharge speed. Causes of discharge failure include air bubbles being mixed into the ink in the liquid discharge head HU, the ink in the liquid discharge head HU becoming more viscous, and paper dust adhering to the nozzle surface FN of the liquid discharge head HU, which will be described later. Here, the ink discharge manner specified by the drive signal Com means that the piezoelectric element 111f discharges an amount of ink specified by the waveform of the drive signal Com, and the piezoelectric element 111f discharges the ink at a discharge speed specified by the waveform of the drive signal Com. In other words, a state in which ink cannot be ejected according to the ink ejection pattern defined by the drive signal Com includes not only a state in which ink cannot be ejected from nozzle Nz, but also a state in which less ink than the amount of ink ejected defined by the drive signal Com is ejected from nozzle Nz, a state in which more ink than the amount of ink ejected defined by the drive signal Com is ejected from nozzle Nz, or a state in which the ink cannot be ejected at the desired landing position on the medium PP because the ink is ejected at a speed different from the ink ejection speed defined by the drive signal Com. In the following, nozzle Nz that is the subject of the ejection state determination may be referred to as "determined nozzle Nz-H".

[0060] In the ejection state determination process, the inkjet printer 100 first selects a nozzle Nz-H to be determined from among 2M nozzles Nz using a control circuit 170, second drives the nozzle Nz-H to be determined under the control of the control circuit 170 to generate residual vibration in the pressure chamber CV communicating with the nozzle Nz-H, third generates a residual vibration signal NES based on the detection signal Vout detected from the piezoelectric element 111f that detected the residual vibration using a detection circuit 117, and fourth generates individual residual vibration information NEI related to the residual vibration based on the residual vibration signal NES using a generation circuit 190.

[0061] Furthermore, the inkjet printer 100 according to this embodiment performs maintenance processing to restore the ejection failure of a nozzle Nz having ejection failure using a maintenance mechanism 145. The maintenance processing includes a flushing process to discharge ink from the nozzle Nz, a wiping process to wipe off foreign matter such as paper dust attached to the vicinity of the nozzle Nz with a wiper 147, and a pumping process to suck up ink, air bubbles, etc. from inside the nozzle Nz with a tube pump. The flushing process is a process that forcibly removes thickened ink and air bubbles mixed in the ink by repeatedly driving a piezoelectric element 111f with a drive signal Com for the flushing process. The maintenance mechanism 145 includes a cap 146 for covering the liquid ejection head HU so as to seal the nozzle Nz, a wiper 147, a tube pump (not shown) for sucking up ink, air bubbles, etc., and an ink receiving unit (not shown) for receiving the discharged ink when discharging ink. The maintenance mechanism 145 is provided in a region that does not overlap with the medium PP when viewed in the Z-axis direction.

[0062] Figure 6 is a cross-sectional view showing an example configuration of the head chip 111. However, in Figure 6, the drive circuit 112 is also shown in addition to the head chip 111. The head chip 111 has a configuration that is approximately symmetrical with respect to the X-axis. However, the positions of the nozzles Nz in nozzle row La and the multiple nozzles Nz in nozzle row Lb along the Y-axis may coincide or differ. In Figure 6, a configuration in which the positions of the multiple nozzles Nz in nozzle row La and the multiple nozzles Nz in nozzle row Lb along the Y-axis coincide is illustrated.

[0063] As shown in Figure 6, the head chip 111 includes a flow channel substrate 111a, a pressure chamber substrate 111b, a nozzle plate 111c, a vibration absorber 111d, a diaphragm 111e, a plurality of piezoelectric elements 111f, a protective plate 111g, a case 111h, and a wiring board 111i.

[0064] The flow channel substrate 111a and the pressure chamber substrate 111b are stacked in this order in the Z1 direction, forming a flow channel for supplying ink to multiple nozzles Nz. In the region located in the Z1 direction from the stack consisting of the flow channel substrate 111a and the pressure chamber substrate 111b, the diaphragm 111e, multiple piezoelectric elements 111f, a protective plate 111g, a case 111h, and a wiring board 111i are installed. On the other hand, in the region located in the Z2 direction from the said stack, the nozzle plate 111c and a vibration absorber 111d are installed. Each element of the head chip 111 is generally a plate-shaped member that is elongated in the Y direction, and is joined to each other, for example, by adhesive. The elements of the head chip 111 will be described in order below.

[0065] The nozzle plate 111c is a plate-shaped member provided with multiple nozzles Nz in nozzle rows La and Lb, respectively. Each of the multiple nozzles Nz is a through-hole through which ink passes. Here, the surface of the nozzle plate 111c facing the Z2 direction is the nozzle surface FN. The nozzle plate 111c is manufactured by processing a silicon single crystal substrate using semiconductor manufacturing technology, such as dry etching or wet etching. However, other known methods and materials may be used in the manufacture of the nozzle plate 111c as appropriate. Furthermore, the cross-sectional shape of the nozzles Nz is typically circular, but is not limited to this, and may be non-circular, such as polygonal or elliptical.

[0066] The flow channel substrate 111a is provided with a space R1, a plurality of supply channels Ra, and a plurality of communication channels Na for each of the nozzle rows La and Lb. Space R1 is an elongated opening extending in the direction along the Y axis when viewed in a plan view along the Z axis. Each of the supply channels Ra and communication channels Na is a through-hole formed for each nozzle Nz. Each supply channel Ra communicates with space R1.

[0067] The pressure chamber substrate 111b is a plate-shaped member provided with a plurality of pressure chambers CV, called cavities, for each of the nozzle rows La and Lb. The plurality of pressure chambers CV are arranged in the direction along the Y axis. Each pressure chamber CV is formed for each nozzle Nz and is a long space extending in the direction along the X axis in a plan view. The flow channel substrate 111a and the pressure chamber substrate 111b are manufactured, for example, by processing a silicon single crystal substrate using semiconductor manufacturing technology, similar to the nozzle plate 111c described above. However, other known methods and materials may be used as appropriate for the manufacture of the flow channel substrate 111a and the pressure chamber substrate 111b.

[0068] The pressure chamber CV is a space located between the flow channel substrate 111a and the diaphragm 111e. For each of the nozzle rows La and Lb, multiple pressure chambers CV are arranged in a direction along the Y axis. The pressure chambers CV also communicate with the communication channel Na and the supply channel Ra, respectively. Therefore, the pressure chambers CV communicate with the nozzle Nz via the communication channel Na and with the space R1 via the supply channel Ra.

[0069] A diaphragm 111e is positioned on the surface of the pressure chamber substrate 111b facing the Z1 direction. The diaphragm 111e is an elastically vibrating plate-shaped member. The diaphragm 111e has, for example, a first layer and a second layer, which are stacked in this order in the Z1 direction. The first layer is, for example, an elastic film composed of silicon oxide (SiO2). This elastic film is formed, for example, by thermal oxidation of one surface of a silicon single crystal substrate. The second layer is, for example, an insulating film composed of zirconium oxide (ZrO2). This insulating film is formed, for example, by forming a zirconium layer by sputtering and then thermally oxidizing the layer. Note that the diaphragm 111e is not limited to the stacked configuration of the first and second layers described above, and may be composed of, for example, a single layer or three or more layers.

[0070] On the surface of the diaphragm 111e facing the Z1 direction, multiple piezoelectric elements 111f are arranged for each nozzle row La and nozzle row Lb, corresponding to the nozzle Nz. Each piezoelectric element 111f is a passive element that deforms in response to the supply of a drive signal Com. Each piezoelectric element 111f is elongated in shape, extending along the X-axis in a plan view. The multiple piezoelectric elements 111f are arranged along the Y-axis to correspond to the multiple pressure chambers CV. The piezoelectric elements 111f overlap the pressure chambers CV in a plan view.

[0071] Figure 7 is an enlarged cross-sectional view of the vicinity of the piezoelectric element 111f. However, in Figure 7, the protective plate 111g is omitted from the drawing to avoid complexity.

[0072] As illustrated in Figure 7, the piezoelectric element 111f is a laminate in which a piezoelectric material Zm is interposed between an upper electrode Zu to which an offset potential VBS is supplied and a lower electrode Zd to which a drive signal Com is supplied. The piezoelectric element 111f is, for example, the portion where the lower electrode Zd, the upper electrode Zu, and the piezoelectric material Zm overlap when viewed from the Z1 direction. A pressure chamber CV is provided in the Z2 direction of the piezoelectric element 111f. In the first embodiment, the offset potential VBS is supplied to the upper electrode Zu and the drive signal Com is supplied to the lower electrode Zd, but it is also possible that the drive signal Com is supplied to the upper electrode Zu and the offset potential VBS is supplied to the lower electrode Zd.

[0073] In the first embodiment, the lower electrode Zd is an individual electrode arranged spaced apart from each other for each piezoelectric element 111f. On the other hand, the upper electrode Zu is a strip-shaped common electrode extending in the direction along the Y axis so as to be continuous across multiple piezoelectric elements 111f. Examples of metallic materials for the lower electrode Zd and the upper electrode Zu include platinum (Pt), aluminum (Al), nickel (Ni), gold (Au), and copper (Cu). One of these can be used alone, or two or more can be used in combination in the form of an alloy or laminate.

[0074] The piezoelectric element Zm is made of a piezoelectric material such as lead zirconate titanate (Pb(Zr,Ti)O3) and, for example, is a strip-shaped material that extends along the Y-axis so as to be continuous across multiple piezoelectric elements 111f. However, the piezoelectric element Zm may be a single unit across multiple piezoelectric elements 111f. In this case, the piezoelectric element Zm is provided with through-holes extending along the X-axis in regions corresponding to the gaps between adjacent pressure chambers CV in a plan view. When the diaphragm 111e vibrates in conjunction with the deformation of the piezoelectric elements 111f, the pressure in the pressure chamber CV fluctuates, causing ink to be ejected from the nozzle Nz.

[0075] Let's return to the explanation in Figure 6. The protective plate 111g is a plate-shaped member installed on the surface of the diaphragm 111e facing the Z1 direction, protecting the multiple piezoelectric elements 111f and reinforcing the mechanical strength of the diaphragm 111e. Here, the multiple piezoelectric elements 111f are housed between the protective plate 111g and the diaphragm 111e. The protective plate 111g is made of, for example, a resin material.

[0076] Case 111h is a component for storing ink supplied to multiple pressure chambers CV. Case 111h is made of, for example, a resin material. Each nozzle row La and nozzle row Lb in case 111h is provided with a space R2. Space R2 is in communication with the aforementioned space R1 and, together with space R1, functions as a reservoir R for storing ink supplied to the multiple pressure chambers CV. Case 111h is provided with an inlet IH for supplying ink to each reservoir R. The ink in each reservoir R is supplied to the pressure chambers CV via each supply channel Ra.

[0077] The vibration absorber 111d, also called the compliance substrate, is a flexible resin film that forms the wall surface of the reservoir R and absorbs pressure fluctuations of the ink in the reservoir R. The vibration absorber 111d may also be a thin, flexible metal plate. The surface of the vibration absorber 111d facing the Z1 direction is joined to the flow channel substrate 111a by adhesive or the like.

[0078] The wiring board 111i is mounted on the surface of the diaphragm 111e facing the Z1 direction and is a mounting component for electrically connecting the head chip 111, the drive circuit 112, and the control module CM, etc. The wiring board 111i is a flexible wiring board such as COF, FPC, or FFC. The aforementioned drive circuit 112 is mounted on the wiring board 111i of this embodiment. COF is an abbreviation for Chip On Film. FPC is an abbreviation for Flexible Printed Circuit. FFC is an abbreviation for Flexible Flat Cable.

[0079] In the following, assuming that n1 is a or b and m1 is any integer from 1 to M, elements related to nozzle Nz[n1m1] may be described with the prefix [n1m1]. For example, a pressure chamber CV communicating with nozzle Nz[n1m1] may be described as pressure chamber CV[n1m1], and a piezoelectric element 111f that applies pressure to pressure chamber CV[n1m1] may be described as piezoelectric element 111f[n1m1]. Similarly, elements related to the nozzle Nz-H to be judged may be described with the prefix "-H". For example, a pressure chamber CV communicating with the nozzle Nz-H to be judged may be described as "pressure chamber CV-H to be judged", and a piezoelectric element 111f that applies pressure to pressure chamber CV-H to be judged may be described as "pressure chamber 111f-H to be judged".

[0080] 1-5. Configuration of the liquid dispensing head HU The configuration of the liquid discharge head HU will be described below with reference to Figure 8.

[0081] Figure 8 is a block diagram showing an example of the configuration of a liquid discharge head HU. Figure 8 shows the head chip 111 and the drive circuit 112 provided on the liquid discharge head HU.

[0082] In addition to the head chip 111 and the drive circuit 112, the liquid discharge head HU includes internal wiring LHa to which the drive signal Com-A is supplied from the drive signal generation circuit 114, internal wiring LHb to which the drive signal Com-B is supplied from the drive signal generation circuit 114, internal wiring LHs for supplying the detection signal Vout detected from the piezoelectric element 111f to the detection circuit 117, and internal wiring LHd to which the offset potential VBS is supplied.

[0083] As shown in Figure 8, the switching circuit 115 comprises 2M switches SWa[a1] to SWa[bM], 2M switches SWb[a1] to SWb[bM], 2M switches SWs[a1] to SWs[bM], and a connection state specification circuit 116 that specifies the connection state of each switch. For example, transmission gates can be used as each switch. The connection status specification circuit 116 generates connection status specification signals SLa[a1]~SLa[bM] that specify the on / off state of switches SWa[a1]~SWa[bM], connection status specification signals SLb[a1]~SLb[bM] that specify the on / off state of switches SWb[a1]~SWb[bM], and connection status specification signals SLs[a1]~SLs[bM] that specify the on / off state of switches SWs[a1]~SWs[bM], based on at least some of the print signal SI, latch signal LAT, and period specification signal Tsig supplied from the control circuit 170.

[0084] If n1 is a or b and m1 is any integer from 1 to M, the switch SWa[n1m1] switches between conduction and non-conductivity between the internal wiring LHa and the lower electrode Zd[n1m1] of the piezoelectric element 111f[n1m1], according to the connection status signal SLa[n1m1]. For example, the switch SWa[n1m1] turns on when the connection status signal SLa[n1m1] is high level and turns off when it is low level. If n1 is a or b and m1 is any integer from 1 to M, the switch SWb[n1m1] switches between conduction and non-conductivity between the internal wiring LHb and the lower electrode Zd[n1m1] of the piezoelectric element 111f[n1m1], according to the connection status signal SLb[n1m1]. For example, the switch SWb[n1m1] turns on when the connection status signal SLb[n1m1] is high level and turns off when it is low level. If n1 is a or b and m1 is any integer from 1 to M, the switch SWs[n1m1] switches between conduction and non-conductivity between the internal wiring LHs and the lower electrode Zd[n1m1] of the piezoelectric element 111f[n1m1], according to the connection status signal SLs[n1m1]. For example, the switch SWs[n1m1] turns on when the connection status signal SLs[n1m1] is high level and turns off when it is low level.

[0085] When n1 is a or b and m1 is any integer from 1 to M, the detection circuit 117 receives the detection signal Vout[n1m1] output from the piezoelectric element 111f[n1m1] via the internal wiring LHs. The detection circuit 117 then generates a residual vibration signal NES based on this detection signal Vout[n1m1]. The residual vibration signal NES is an analog signal.

[0086] The detection circuit 117 may include, for example, a negative feedback amplifier for amplifying the detection signal Vout, a low-pass filter for attenuating the high-frequency components of the detection signal Vout, and a voltage follower that converts impedance to output a low-impedance residual vibration signal NES.

[0087] The generation circuit 190 generates individual residual vibration information NEI based on the residual vibration signal NES. Individual residual vibration information NEI is a digital signal. For example, the generation circuit 190 samples the residual vibration signal NES at regular intervals and generates individual residual vibration information NEI by associating time information, which indicates the time of sampling with respect to an arbitrary starting point, with a value indicating the potential obtained from the sampling.

[0088] 1-6. Operation of the liquid dispensing head HU The operation of the liquid ejection head HU will be described below with reference to Figure 9. In this embodiment, the operating period of the inkjet printer 100 includes one or more recording periods Tu. In this embodiment, the inkjet printer 100 is assumed to perform either driving each piezoelectric element 111f in the recording process or driving the target piezoelectric element 111f-H and detecting residual vibration in the preparation process for the ejection state determination process during each recording period Tu. However, this disclosure is not limited to this embodiment, and it may be possible to perform both driving each piezoelectric element 111f in the recording process and driving the target piezoelectric element 111f-H and detecting residual vibration in the preparation process for the ejection state determination process during each recording period Tu. Generally, an inkjet printer 100 forms an image based on image data Img by ejecting ink from each nozzle Nz one or more times over multiple continuous or intermittent recording periods Tu. In addition, the inkjet printer 100 according to this embodiment performs a preparatory process for ejection state determination processing 2M times over 2M recording periods Tu which are provided continuously or intermittently, thereby performing an ejection state determination process with each of the 2M nozzles Nz[a1] to D[bM] as the nozzle Nz-H to be determined.

[0089] Figure 9 is a timing chart illustrating the operation of the inkjet printer 100 during the recording period Tu. As shown in Figure 9, the control circuit 170 outputs a latch signal LAT having a pulse PlsL. Thus, the control circuit 170 defines the recording period Tu as the period from the rising edge of pulse PlsL to the rising edge of the next pulse PlsL.

[0090] The print signal SI includes individual designation signals Sd[a1] to Sd[bM] that specify the mode of driving the piezoelectric elements 111f[a1] to D[bM] during each recording period Tu. When at least one of the recording process and the ejection state determination process is performed during the recording period Tu, the control circuit 170 supplies the print signal SI, including the individual designation signals Sd[a1] to Sd[bM], to the connection state designation circuit 116 in synchronization with the clock signal CL prior to the start of the recording period Tu, as shown in Figure 9. In this case, if n1 is a or b and m1 is any integer from 1 to M, the connection state designation circuit 116 generates connection state designation signals SLa[n1m1], SLb[n1m1], and SLs[n1m1] during the recording period Tu based on the individual designation signal Sd[n1m1].

[0091] Furthermore, if n1 is a or b and m1 is any integer from 1 to M, the individual designation signal Sd[n1m1] according to this embodiment is a signal that, for each recording period Tu, specifies to the piezoelectric element 111f[n1m1] one of three drive modes: ink ejection, non-ejection of ink, and drive as the target of determination in the ejection state determination process.

[0092] As shown in Figure 9, the drive signal generation circuit 114 outputs a drive signal Com-A having an output waveform PX. The output waveform PX has a minimum potential VLX and a maximum potential VHX. The output waveform PX has its start and end potentials set to the reference potential V0.

[0093] Then, assuming that n1 is a or b and m1 is any integer from 1 to M, if the individual designation signal Sd[n1m1] specifies ink ejection to the piezoelectric element 111f[n1m1], the connection state designation circuit 116 sets the connection state designation signal SLa[n1m1] to a high level during the recording period Tu, and sets the connection state designation signals SLb[n1m1] and SLs[n1m1] to low levels during the recording period Tu. In this case, the nozzle Nz[n1m1] ejects ink during the recording period Tu, and dots are formed on the medium PP.

[0094] As shown in Figure 9, the drive signal generation circuit 114 outputs a drive signal Com-B having a test waveform PS provided during the recording period Tu. In this embodiment, the test waveform PS is determined such that the potential difference between the highest potential VHS and the lowest potential VLS of the test waveform PS is smaller than the potential difference between the highest potential VHX and the lowest potential VLX of the ejection waveform PX. Specifically, assuming that n1 is a or b and m1 is any integer from 1 to M, when the drive signal Com-B having the test waveform PS is supplied to the piezoelectric element 111f[n1m1], the test waveform PS is determined such that the piezoelectric element 111f[n1m1] is driven to the extent that no ink is ejected from the nozzle Nz[n1m1]. Note that the potential of the test waveform PS at the start and end is set to the reference potential V0.

[0095] Furthermore, the control circuit 170 outputs a period specification signal Tsig having pulses PlsT1 and PlsT2. As a result, the control circuit 170 divides the recording period Tu into three control periods: TSS1, from the start of pulse PlsL to the start of pulse PlsT1; TSS2, from the start of pulse PlsT1 to the start of pulse PlsT2; and TSS3, from the start of pulse PlsT2 to the start of the next pulse PlsL.

[0096] Furthermore, assuming that n1 is a or b and m1 is any integer from 1 to M, if the individual designation signal Sd[n1m1] designates nozzle Nz[n1m1] as the nozzle Nz-H to be determined, the connection state designation circuit 116 sets the connection state designation signal SLa[n1m1] to a low level during the recording period Tu, sets the connection state designation signal SLb[n1m1] to a high level during the control periods TSS1 and TSS3 and to a low level during the control period TSS2, and sets the connection state designation signal SLs[n1m1] to a low level during the control periods TSS1 and TSS3 and to a high level during the control period TSS2. In this case, the piezoelectric element 111f-H to be judged is driven by the drive signal Com-B of the inspection waveform PS during the control period TSS1. The piezoelectric element 111f is displaced by the drive signal Com-B of the inspection waveform PS during the control period TSS1. As a result, vibration occurs in the pressure chamber CV-H to be judged, and this vibration persists during the control period TSS2. During the control period TSS2, the lower electrode Zd of the piezoelectric element 111f-H changes its potential in accordance with the residual vibration occurring in the pressure chamber CV-H. In other words, during the control period TSS2, the lower electrode Zd of the piezoelectric element 111f-H exhibits a potential corresponding to the electromotive force of the piezoelectric element 111f caused by the residual vibration occurring in the pressure chamber CV-H. The potential of the lower electrode Zd can be detected as a detection signal Vout during the control period TSS2.

[0097] 1-7. Causes of dispensing failure The liquid ejection head HU contains electronic components such as the drive circuit 112, and therefore deteriorates over time as it is used. To assess the degree of this deterioration, it is conceivable to perform residual vibration analysis. However, when a head manufacturer provides the liquid ejection head HU to a printer manufacturer, ejection failures may occur not only due to the liquid ejection head HU itself, such as deterioration over time, but also due to causes unrelated to the liquid ejection head HU. Specifically, ejection failures caused by unrelated causes may occur due to problems in the transport mechanism 140, including the encoder and transport rollers, causing the media PP to lift, or the distance between the liquid ejection head HU and the media PP to be set narrower than the recommended distance, resulting in collision between the media PP and the nozzle surface FN of the liquid ejection head HU. As a result of the collision between the media PP and the nozzle surface FN, scratches may occur on the nozzle Nz, or solidified ink may adhere to the vicinity of the nozzle Nz, causing ejection failures.

[0098] The head manufacturer is improving the liquid discharge head (HU) to resolve dispensing failures. If the dispensing failure is caused by a problem with the liquid discharge head (HU), the head manufacturer can improve the problem by modifying the HU. However, dispensing failures not caused by the liquid discharge head (HU) are often not improved by modifying the HU. Furthermore, residual vibration analysis used to assess aging degradation sometimes incorrectly identified dispensing failures not caused by the liquid discharge head (HU) as being caused by it. Consequently, the head manufacturer sometimes failed to properly improve the liquid discharge head (HU) when attempting to improve it without realizing that the dispensing failure was not caused by it. Therefore, there was a need for a system that could accurately determine whether an anomaly was caused by the media (PP) colliding with the liquid discharge head (HU).

[0099] The inventors have found that because the spacing between the 2M nozzles Nz is very narrow, when the medium PP collides with the liquid discharge head HU, discharge failures tend to occur in multiple consecutive nozzles Nz. Therefore, in this embodiment, when an abnormality is detected in multiple consecutive nozzles Nz, it is determined that the abnormality is caused by the medium PP colliding with the liquid discharge head HU. In this embodiment, consecutive nozzles Nz refer to nozzles Nz located in the direction of the nozzle row. Thus, if m1 is an integer from 1 to M, the nozzles Nz consecutive to nozzle Nz[am1], which is divided into nozzle row La, are the J nozzles Nz from nozzle Nz[am1+1] to nozzle Nz[am1+J]. The value of J can be any integer between 1 and M, but it is preferably 9 or greater.

[0100] In the following, abnormalities caused by the media PP colliding with the liquid ejection head HU may be referred to as "media collision abnormalities," while abnormalities of the liquid ejection head HU that originate from the liquid ejection head HU, such as the inclusion of air bubbles, ink viscosity increase, and leakage, may be referred to as "previously described head abnormalities." Note that media collision abnormalities are an example of "Type 1 abnormalities," and previously described head abnormalities are an example of "Type 2 abnormalities."

[0101] 1-8. Functions and Operation of Inkjet System 10 The functions and operation of the inkjet system 10 will be explained using Figures 10 to 13. In this embodiment, the cloud server CS performs an abnormality determination process and provides the inkjet printer 100 with a service that provides determination information JI indicating the determination result. The abnormality / defect determination process is a process that determines whether there is a media collision abnormality, a previously printed head abnormality, or a normal state that is neither a media collision abnormality nor a previously printed head abnormality, based on residual vibration information NI which has 2M individual residual vibration information NEI.

[0102] Figure 10 is a diagram showing the functions of the inkjet system 10. Figure 11 is a flowchart showing the operation of the inkjet system 10. The control circuit 170 functions as the acquisition unit 171, the first transmission unit 173, the first reception unit 175, the maintenance control unit 177, and the notification unit 179 by reading the control program PM3 and executing the read control program PM3. The server 300 functions as the cloud server CS by reading the virtualization program VM and executing the read virtualization program VM. The cloud server CS reads the control program PM1 and executes the control program PM1, thereby functioning as the second reception unit 301, the determination unit 303, and the second transmission unit 305.

[0103] The flowchart shown in Figure 11 is executed, for example, when the inkjet printer 100 receives image data Img from the processing unit 200, before executing the recording process. In step SJ2, the control circuit 170 functions as an acquisition unit 171 to acquire residual vibration information NI. Specifically, the control circuit 170 acquires 2M individual residual vibration information NEI corresponding to 2M nozzles Nz, which will be contained in the residual vibration information NI, from the generation circuit 190. More specifically, the control circuit 170 sets the nozzle Nz[x] to the nozzle Nz-H to be determined for each of a1 to bM, and acquires the individual residual vibration information NEI[x] by executing an ejection state determination process for the nozzle Nz-H to be determined. Step SJ2 is an example of the "acquisition process". After the processing in step SJ2 is completed, in step SJ4, the control circuit 170 functions as the first transmitting unit 173 and controls the communication device 150 to transmit the residual vibration information NI, which has 2M individual residual vibration information NEI acquired by the acquisition unit 171, to the cloud server CS. More specifically, the first transmitting unit 173 transmits the residual vibration information NI to the cloud server CS via the processing unit 200. Step SJ4 is an example of the "transmission process". After the processing in step SJ4 is completed, the control circuit 170 waits for a response from the cloud server CS.

[0104] In step SC2, the cloud server CS functions as the second receiving unit 301 and receives residual vibration information NI from the inkjet printer 100. After the processing in step SC2 is completed, in step SC4, the cloud server CS functions as the determination unit 303 and performs abnormality determination processing for the nozzle row La. The abnormality determination processing for the nozzle row La will be explained using Figure 12.

[0105] Figure 12 is a flowchart showing the abnormality determination process for the nozzle row La. In step SC22, the determination unit 303 uses the amplitude and period of the residual vibration to determine whether or not there is an abnormality in each of the M nozzles Nz that are divided into nozzle row La. The method for determining whether or not the residual vibration for the M nozzles Nz is abnormal will be explained with reference to Figure 13.

[0106] Figure 13 illustrates a method for determining whether residual vibration is abnormal or not. Generally, residual vibration occurring in the pressure chamber CV has a natural vibration frequency determined by the shape of the nozzle Nz, the weight of the ink filled in the pressure chamber CV, and the viscosity of the ink filled in the pressure chamber CV, etc.

[0107] Furthermore, generally, if the nozzle Nz is malfunctioning due to air bubbles being present in the nozzle Nz, the residual vibration frequency will be higher compared to when there are no air bubbles present in the nozzle Nz. Also, generally, if the nozzle Nz is malfunctioning due to foreign matter such as paper dust adhering to the vicinity of the nozzle Nz, the residual vibration frequency will be lower compared to when there is no foreign matter adhering. For example, if the nozzle Nz is malfunctioning due to ink leakage, the residual vibration frequency will be lower compared to when there is no ink leakage. Also, generally, if the nozzle Nz is malfunctioning due to increased viscosity of the ink inside the nozzle Nz, the residual vibration frequency will be lower compared to when the ink inside the nozzle Nz is not increased viscosity. Also, generally, if the nozzle Nz is malfunctioning due to increased viscosity of the ink inside the nozzle Nz, the residual vibration frequency will be lower compared to when there is foreign matter such as paper dust adhering to the vicinity of the nozzle Nz. Furthermore, generally, if the discharge state of the nozzle Nz is abnormal because the pressure chamber CV is not filled with ink, or if the discharge state of the nozzle Nz is abnormal because the piezoelectric element 111f has malfunctioned and cannot be displaced, the amplitude of the residual vibration will decrease.

[0108] Individual residual vibration information (NEI) displays waveforms corresponding to the residual vibrations occurring in the pressure chamber CV. Specifically, the residual vibrations show frequencies corresponding to the frequency of the residual vibrations occurring in the detected pressure chamber CV, and amplitudes corresponding to the amplitude of the residual vibrations occurring in the pressure chamber CV.

[0109] The determination unit 303 measures the time length of one cycle of the individual residual vibration information NEI as the cycle NTc of the individual residual vibration information NEI for one of the M nozzles Nz. Further, the determination unit 303 determines whether the individual residual vibration information NEI has a predetermined amplitude. Specifically, the determination unit 303 determines whether, during the period in which the cycle NTc of the individual residual vibration information NEI is being measured, the potential of the individual residual vibration information NEI becomes equal to or higher than the first threshold potential that is higher than the potential at the amplitude center level of the individual residual vibration information NEI and equal to or lower than the second threshold potential that is lower than the potential at the amplitude center level. And when the result of the determination is affirmative, it is specified that the individual residual vibration information NEI has a predetermined amplitude, and when the result of the determination is negative, it is specified that the individual residual vibration information NEI does not have a predetermined amplitude. Then, the determination unit 303 determines whether there is an abnormality in the residual vibration based on the cycle NTc and the amplitude of the individual residual vibration information NEI.

[0110] Records Rcd1 to Rcd5 in FIG. 13 show the conditions for whether there is an abnormality in the residual vibration. For example, when the amplitude of the individual residual vibration information NEI is equal to or greater than a predetermined amplitude, the determination unit 303 determines whether there is an abnormality in the residual vibration by comparing the cycle NTc of the individual residual vibration information NEI with some or all of the threshold values Tth1, Tth2, and Tth3.

[0111] The threshold value Tth1 is a value for indicating the boundary between the time length of one cycle of the residual vibration when the discharge state of the nozzle Nz is normal and the time length of one cycle of the residual vibration when bubbles are mixed into the pressure chamber CV. Further, the threshold value Tth2 is a value for indicating the boundary between the time length of one cycle of the residual vibration when the discharge state of the nozzle Nz is normal and the time length of one cycle of the residual vibration when foreign matter adheres near the nozzle Nz. Further, the threshold value Tth3 is a value for indicating the boundary between the time length of one cycle of the residual vibration when foreign matter adheres near the nozzle Nz and the time length of one cycle of the residual vibration when the ink in the pressure chamber CV thickens. Note that the threshold values Tth1, Tth2, and Tth3 satisfy "Tth1 < Tth2 < Tth3".

[0112] As shown in record Rcd5, in the present embodiment, for a certain one nozzle Nz[x] among the M nozzles Nz, when the amplitude of the individual residual vibration information NEI[x] is greater than or equal to a predetermined amplitude, and as shown in record Rcd2, the period NTc of the individual residual vibration information NEI[x] satisfies "Tth1 ≤ NTc ≤ Tth2", it is determined that the nozzle Nz[x] is normal.

[0113] For a certain one nozzle Nz[x], when the amplitude of the individual residual vibration information NEI[x] is greater than or equal to a predetermined amplitude, and as shown in record Rcd1, the period NTc of the individual residual vibration information NEI[x] satisfies "NTc < Tth1", it is determined that there is a bubble mixing abnormality in the nozzle Nz[x] due to the mixing of bubbles into the nozzle Nz. Also, for the nozzle Nz[x], when the amplitude of the individual residual vibration information NEI[x] is greater than or equal to a predetermined amplitude, and as shown in record Rcd3, the period NTc of the individual residual vibration information NEI satisfies "Tth2 < NTc ≤ Tth3", it is determined that there is a leakage abnormality in the nozzle Nz[x] due to the leakage of ink from the nozzle Nz[x]. Further, for the nozzle Nz[x], when the amplitude of the individual residual vibration information NEI[x] is greater than or equal to a predetermined amplitude, and as shown in record Rcd4, the period NTc of the individual residual vibration information NEI satisfies "Tth3 < NTc", it is determined that there is a thickening abnormality in the nozzle Nz[x] due to the thickening of the ink in the nozzle Nz.

[0114] When the amplitude of the individual residual vibration information NEI[x] is less than the predetermined amplitude, the determination unit 303 determines that the nozzle Nz[x] is abnormal. In the first embodiment [x], when the amplitude of the individual residual vibration information NEI is less than the predetermined amplitude, the determination unit 303 determines that there is an abnormality in the residual vibration other than the above-mentioned bubble mixing abnormality, exposure abnormality, and thickening abnormality.

[0115] Let's return to the explanation in Figure 12. After the processing in step SC22 is completed, the determination unit 303 assigns 1 to the variable x in step SC24. Next, in step SC26, the determination unit 303 refers to the determination result of step SC22 and determines whether or not there was an abnormality in the nozzle Nz[ax]. If the determination result of step SC26 is positive, the determination unit 303 assigns 1 to the variable j in step SC28. Next, in step SC30, the determination unit 303 refers to the determination result of step SC22 and determines whether or not there was an abnormality in the nozzle Nz[ax+j].

[0116] If the result of step SC30 is positive, the determination unit 303 determines in step SC32 whether the value of variable j is less than J.

[0117] If the result of step SC32 is positive, in step SC34, the determination unit 303 assigns the value of variable j plus 1 to the variable j. After the processing of step SC34 is completed, the determination unit 303 returns the process to step SC30.

[0118] If the result of step SC32 is negative, it means that there was an abnormality in J+1 consecutive nozzles Nz from nozzle Nz[ax] to nozzle Nz[ax+J]. Therefore, if the result of step SC32 is negative, the determination unit 303 determines in step SC36 that a media collision abnormality has occurred.

[0119] If the result of step SC30 is negative, the determination unit 303 determines in step SC38 that a previously reported head abnormality has occurred at nozzle Nz[ax]. If the result of step SC26 is negative, the determination unit 303 determines in step SC40 that nozzle Nz[ax] is discharging normally.

[0120] After the processing in step SC36 is completed, the determination unit 303 determines in step SC42 whether the value of variable x is less than M. After the processing in step SC38 and after the processing in step SC40, the determination unit 303 also terminates the processing in step SC42. If the result of the determination in step SC42 is positive, the determination unit 303 assigns the value of variable x plus 1 to variable x in step SC44. After the processing in step SC44 is completed, the determination unit 303 returns to the processing in step SC26. If the result of the determination in step SC42 is negative, the determination unit 303 terminates the series of processes shown in Figure 12.

[0121] If the value of x is greater than MJ, the value of x+j may exceed M in step SC30. If the value of x+j exceeds M, the determination unit 303 does not execute the process in step SC30, and instead determines that the determination result of step SC30 is negative, and executes the process in step SC38.

[0122] Let's return to the explanation in Figure 11. After the processing in step SC4 is completed, the cloud server CS functions as a determination unit 303 in step SC6 and executes abnormality determination processing for nozzle row Lb. The abnormality determination processing for nozzle row Lb is the same as that for nozzle row La, but with nozzle row Lb being the target of the abnormality determination processing, so the illustration and explanation are omitted. Note that the cloud server CS may execute the processing in step SC4 after executing the processing in step SC6. Hereafter, the abnormality determination processing for nozzle row La and the abnormality determination processing for nozzle row Lb may be referred to as abnormality determination processing without distinction. Steps SC4 and SC6 are examples of "determination steps".

[0123] After the processing of step SC6 is completed, in step SC8, the determination unit 303, with the cloud server CS functioning as the second transmission unit 305, transmits determination information JI indicating the determination result of the determination unit 303 to the inkjet printer 100. The determination information JI includes one or more identifiers from among a first identifier indicating normality, a second identifier indicating that a head error has occurred, and a third identifier indicating that a media collision error has occurred. For example, if the processing of step SC36 of the series of processes shown in Figure 12 is executed, the determination information JI includes the third identifier. Furthermore, if the processing of step SC38 of the series of processes shown in Figure 12 is executed, the determination information JI includes the second identifier. Also, if the determination unit 303 does not execute either the processing of step SC36 or step SC38, the determination information JI includes the first identifier. After the processing of step SC8 is completed, the cloud server CS terminates the series of processes shown in Figure 11.

[0124] Furthermore, after the completion of step SC8, the cloud server CS may store the judgment information JI in the memory circuit 320. The head manufacturer can improve the liquid discharge head HU by analyzing the judgment information JI. In addition, to enable the head manufacturer to improve the liquid discharge head HU more efficiently, the cloud server CS may store the residual vibration information NI and the judgment information JI in association with each other in the memory circuit 320. Moreover, in order to reduce the capacity used by the memory circuit 320, the cloud server CS may store the residual vibration information NI and the judgment information JI in association with each other in the memory circuit 320 only if the judgment information JI contains one or more identifiers from the second identifier and the third identifier.

[0125] After the processing in step SJ4 is completed, the control circuit 170 waits for a response from the cloud server CS, and in step SJ10, the control circuit 170 functions as the first receiving unit 175 and receives judgment information JI from the cloud server CS. Step SJ10 is an example of a "receiving process". After the processing in step SJ10 is completed, in step SJ12, the control circuit 170 functions as the maintenance control unit 177 and controls the maintenance mechanism 145 based on the judgment information JI to resolve the previously reported head abnormality.

[0126] For example, if the judgment information JI contains an identifier indicating an abnormality in the presence of air bubbles, the maintenance control unit 177 instructs the maintenance mechanism 145 to perform a pumping process. Also, if the judgment information JI contains an identifier indicating an abnormality in leakage, the maintenance control unit 177 instructs the maintenance mechanism 145 to perform a wiping process. Furthermore, if the judgment information JI contains an identifier indicating an abnormality in viscosity, the maintenance control unit 177 instructs the maintenance mechanism 145 to perform a flushing process or a pumping process.

[0127] After the processing in step SJ12 is completed, in step SJ14, the control circuit 170 determines whether the determination information JI contains a third identifier indicating a media collision anomaly. If the determination result in step SJ14 is affirmative, in step SJ16, the control circuit 170 functions as a notification unit 179 and transmits notification information regarding the occurrence of a media collision anomaly to the processing unit 200. The notification information is, for example, a first string indicating that a media collision anomaly has occurred. The first string is, for example, "The printing paper may have collided with the liquid ejection head." Furthermore, the notification information may also include a second string indicating an example of how user U should deal with a media collision anomaly. The second string is, for example, "We recommend correcting the settings of the transport mechanism and the setting of the distance between the liquid ejection head and the printing paper." Upon receiving the notification information, the processing unit 200 displays the string indicated by the notification information on the display device 270. Note that the notification information is not limited to a string indicating that a media collision anomaly has occurred, but may also include information showing an image indicating that a media collision anomaly has occurred, and information showing an audio indicating that a media collision anomaly has occurred, or both.

[0128] The control circuit 170 may execute the processing in step SJ14 and step SJ16 before the processing in step SJ12.

[0129] After the processing in step SJ16 is completed, or if the result of the determination in step SJ14 is negative, the control circuit 170 terminates the series of processes shown in Figure 11.

[0130] 1-9. Summary of the First Embodiment To facilitate understanding, the individual residual vibration information NEI relating to the residual vibration in the pressure chamber CV communicating with the target nozzle Nz among the 2M nozzles Nz will be referred to as "first individual information," and the J individual residual vibration information NEI relating to the J residual vibrations in each of the J pressure chambers CV communicating with each of the 1 or more J nozzles Nz continuous with the target nozzle Nz will be referred to as "second individual information," and the summary of the first embodiment will be described below.

[0131] The first embodiment defines a control method for an inkjet printer 100 that ejects ink onto a medium PP, having 2M piezoelectric elements 111f, 2M pressure chambers CV that apply pressure to the ink inside by driving the piezoelectric elements 111f, and a liquid ejection head HU having 2M nozzles Nz that communicate with each of the 2M pressure chambers CV and eject ink. This control method involves the following steps: step SJ2, which involves acquiring residual vibration information NI regarding residual vibration in the pressure chambers CV after applying a voltage to one or more of the 2M piezoelectric elements 111f; and steps SC6 and SC8, which involve determining whether a medium collision abnormality has occurred, which is an abnormality caused by the medium PP colliding with the liquid ejection head HU, based on the residual vibration information NI. According to the first embodiment, when the medium PP collides with the liquid ejection head HU, ejection failures tend to occur in a series of nozzles Nz, allowing for accurate determination of whether a medium collision abnormality has occurred. For example, if a medium collision abnormality has occurred, the head manufacturer does not need to investigate the cause to improve the liquid ejection head HU, thus reducing the burden on the head manufacturer in improving the liquid ejection head HU. Furthermore, the inkjet printer 100 can notify the printer manufacturer or user U that a medium collision abnormality has occurred. When the printer manufacturer or user U learns that a medium collision abnormality has occurred, they can prevent the medium collision abnormality from occurring again by setting the distance between the liquid ejection head HU and the medium PP to be appropriately maintained.

[0132] The residual vibration information NI includes first individual information and second individual information. The determination unit 303 determines that a media collision abnormality has occurred if an abnormality is detected in all of the residual vibrations related to the first individual information and all J residual vibrations related to the second individual information during the processing of step SC6 and step SC8. As mentioned above, if an anomaly is detected in J+1 consecutive nozzles Nz, it is highly likely that the cause is a collision between the medium PP and the liquid discharge head HU. Therefore, by determining that a medium collision anomaly has occurred when an anomaly is detected in J+1 consecutive nozzles Nz, it is possible to accurately determine whether or not a medium collision anomaly has occurred.

[0133] Furthermore, the determination unit 303 determines that no media collision abnormality has occurred if, in the processing of step SC4 and step SC6, an abnormality is detected in the residual vibration related to the first individual information, and no abnormality is detected in any of the J residual vibrations related to the second individual information. Even if an abnormality is detected in the target nozzle Nz, if no abnormality occurs in the nozzle Nz adjacent to the target nozzle Nz, it is highly likely that only the previously reported head abnormality occurred in the target nozzle Nz, and the medium PP did not collide with the liquid discharge head HU. Therefore, by determining that no medium collision abnormality has occurred when no abnormality occurs in the nozzle Nz adjacent to the target nozzle Nz, it is possible to accurately determine whether or not a medium collision abnormality has occurred.

[0134] Furthermore, J nozzles Nz is equivalent to 9 or more nozzles Nz. The spacing between the 2M nozzles Nz is very narrow. For example, if the resolution of the image formed by M nozzles Nz divided into one nozzle row is 300 dpi, the spacing between two nozzles Nz is 25.4 mm / 300, which is approximately 0.085 mm. Therefore, if the medium PP collides with the liquid discharge head HU, there is a high probability that discharge failures will occur in many consecutive nozzles Nz. On the other hand, the aforementioned head abnormality may occur in two or three consecutive nozzles Nz out of the 2M nozzles Nz. Therefore, if J nozzles Nz are three nozzles Nz, there is a high possibility of misjudging that a medium collision abnormality has occurred even though the medium PP has not collided with the liquid discharge head HU. Therefore, according to the first embodiment, the accuracy of determining whether or not a medium collision abnormality has occurred can be improved compared to the embodiment in which J nozzles Nz are fewer than nine nozzles Nz.

[0135] Furthermore, in the processing of step SC6 and step SC8, the determination unit 303 further determines, based on the first individual information, whether or not a previously reported head abnormality has occurred, which is an abnormality different from a media collision abnormality and is an abnormality of the liquid discharge head HU caused by the liquid discharge head HU. According to the first embodiment, it is possible to accurately determine whether or not a media collision error has occurred while simultaneously determining whether or not a previously reported head error has occurred.

[0136] Furthermore, the determination unit 303 determines that a previously reported head abnormality has occurred if, in the processing of step SC6 and step SC8, an abnormality is detected from the residual vibration related to the first individual information, and no abnormality is detected in any of the J residual vibrations related to the second individual information. If no abnormality is detected in any of the J residual vibrations related to the second individual information, it means that no abnormality has occurred in the continuous nozzle Nz, and if an abnormality is detected in the nozzle Nz, it means that a previously reported head abnormality has occurred. Therefore, according to the first embodiment, the accuracy of determining whether or not a previously reported head abnormality has occurred can be improved by determining that a previously reported head abnormality has occurred if no abnormality is detected in any of the J residual vibrations related to the second individual information.

[0137] The control method for the inkjet printer 100 uses a cloud server CS located outside the inkjet printer 100. This control method further involves, when residual vibration information NI is acquired through the processing in step SJ2, the processing in step SJ4 to send the residual vibration information NI from the inkjet printer 100 to the cloud server CS, and the processing in step SJ10 to receive judgment information JI indicating the judgment result by the judgment unit 303 from the cloud server CS, and the cloud server CS performs abnormality judgment processing as the judgment unit 303. In other words, the cloud server CS performs abnormality judgment processing and provides the inkjet printer 100 with a service that provides judgment information JI indicating the judgment result. A service that provides judgment information JI may be offered for a limited time. It is also possible for the inkjet printer 100 to perform abnormality detection processing. Therefore, one possible configuration in which the inkjet printer 100 performs abnormality detection processing is to provide the service that provides judgment information JI to the printer manufacturer for a limited time. However, in the configuration in which the inkjet printer 100 performs abnormality detection processing, the program that performs abnormality detection processing is stored in the memory circuit 160. As a result of the printer manufacturer illegally analyzing the program that performs abnormality detection processing, there is a risk that after the period for which the service that provides judgment information JI is offered has expired, the printer manufacturer may use the results of the illegal analysis to independently implement abnormality detection processing. In the first embodiment, since the entity that executes the abnormality detection processing is the cloud server CS, it is possible to provide the service that provides judgment information JI to the printer manufacturer for a limited time while suppressing the leakage of the program that performs abnormality detection processing.

[0138] 2. Second Embodiment In the first embodiment, the determination unit 303 uses the amplitude and period of residual vibration to determine whether a media collision abnormality has occurred and whether a previously reported head abnormality has occurred, but is not limited to this. In the second embodiment, the determination unit 303 uses the amplitude of residual vibration to determine whether a media collision abnormality has occurred, and uses the amplitude and period of residual vibration to determine whether a previously reported head abnormality has occurred. The second embodiment will be described below.

[0139] 2-1. Function and operation of the inkjet system 10 in the second embodiment Figure 14 is a flowchart showing the operation of the inkjet system 10 in the second embodiment. The flowchart in Figure 14 differs from the flowchart in Figure 11 in that it performs the processes of steps SC4A1 and SC4A2 instead of step SC4, and performs the processes of steps SC6A1 and SC6A2 instead of step SC6, but is the same in other respects. Below, only the differences from the flowchart in Figure 11 will be explained.

[0140] After the completion of step SC2, the cloud server CS functions as a determination unit 303 and, in step SC4A1, performs a media collision abnormality determination process for the nozzle row La. The media collision abnormality determination process for the nozzle row La will be explained with reference to Figure 15.

[0141] Figure 15 is a flowchart showing the process for determining media collision abnormalities in nozzle row La. The flowchart in Figure 15 differs from the flowchart in Figure 12 in that it executes the process of step SC22A instead of step SC22, and the process of step SC38A instead of step SC38, but otherwise it is the same. Below, only the differences from the flowchart in Figure 12 will be explained.

[0142] In step SC22A, the determination unit 303 uses the amplitude of the residual vibration, without using the period of the residual vibration, to determine whether there is an abnormality in each of the M nozzles Nz that are divided into nozzle row La. For example, if the amplitude of the residual vibration corresponding to one of the M nozzles Nz is less than a predetermined amplitude, the determination unit 303 determines that this one nozzle Nz is abnormal.

[0143] If the result of step SC30 is negative, the determination unit 303 determines in step SC38A that no media collision abnormality occurred at nozzle Nz[ax].

[0144] Let's return to the explanation in Figure 14. After the processing in step SC4A1 is completed, the cloud server CS functions as a determination unit 303 and, in step SC4A2, performs the process of determining if a head has already been used in nozzle row La is abnormal. The process of determining if a head has already been used in nozzle row La is explained using Figure 16.

[0145] Figure 16 is a flowchart showing the process for determining previously identified head abnormalities in nozzle row La. The flowchart in Figure 16 differs from the flowchart in Figure 12 in that if the determination result in step SC26 is positive, the process in step SC38 is executed, and the processes in steps SC28, SC30, SC32, SC34, and SC36 are not executed. In other respects, it is the same. Each process shown in Figure 16 is identical to one of the processes in the series of processes shown in Figure 12, so a description is omitted.

[0146] The explanation returns to Figure 14. After the processing of step SC4A2 is completed, the cloud server CS functions as a determination unit 303 and, in step SC6A1, executes a media collision anomaly determination process for nozzle row Lb. The media collision anomaly determination process for nozzle row Lb is omitted from the illustration and explanation because it is the same as the process for nozzle row La, where the nozzle row subject to the media collision anomaly determination process is replaced with nozzle row Lb. After the processing of step SC6A1 is completed, the cloud server CS functions as a determination unit 303 and, in step SC6A2, executes a previously output head anomaly determination process for nozzle row Lb. The previously output head anomaly determination process for nozzle row Lb is the same as the same as the process for nozzle row La, where the nozzle row subject to the previously output head anomaly determination process is replaced with nozzle row Lb. Therefore, the illustration and explanation are omitted. In the second embodiment, steps SC4A1, SC4A2, SC6A1, and SC6A2 are examples of "determination steps". After the processing of step SC6A2 is completed, the cloud server CS executes the processing of step SC8.

[0147] 2-2. Summary of the Second Embodiment To facilitate understanding, the individual residual vibration information NEI relating to the residual vibration in the pressure chamber CV communicating with the target nozzle Nz among the 2M nozzles Nz will be referred to as "first individual information," and the J individual residual vibration information NEI relating to the J residual vibrations in each of the J pressure chambers CV communicating with each of the 1 or more J nozzles Nz continuous with the target nozzle Nz will be referred to as "second individual information," and the summary of the second embodiment will be described below.

[0148] In the processing of step SC4A1 and step SC6A1, the determination unit 303 determines whether or not a media collision abnormality has occurred, using the amplitude of residual vibration related to the first individual information and the second individual information, but without using the period of residual vibration related to the first individual information and the second individual information. When the medium PP collides with the liquid ejection head HU, scratches may occur on the nozzle Nz or solidified ink may adhere near the nozzle Nz. As a result, even when the drive signal Com is applied to the piezoelectric element 111f, ink tends not to be ejected. The amplitude of residual vibration when ink is not ejected tends to be smaller than the amplitude of residual vibration assumed by the head manufacturer. Therefore, in determining whether or not a medium collision abnormality has occurred, it is sufficient to use only the amplitude of residual vibration and not the period of residual vibration. Accordingly, according to the second embodiment, compared to the method of performing the medium collision abnormality determination process using both the amplitude and period of residual vibration, the amount of processing required to determine whether or not a medium collision abnormality has occurred can be reduced while maintaining the accuracy of the determination.

[0149] In the processing of step SC4A2 and step SC6A2, the determination unit 303 uses the amplitude and period of residual vibration related to the first individual information and the second individual information to determine whether or not a previously reported head abnormality has occurred. As shown in Figure 13, when a previously reported head abnormality occurs, one or more of the following abnormalities have occurred: air bubbles, ink viscosity, and leakage. By using the amplitude and period of residual vibration, it is possible to accurately determine whether one or more of these abnormalities have occurred. Furthermore, the maintenance control unit 177 needs to have the maintenance mechanism 145 perform processing according to each abnormality in order to resolve the air bubbles, ink viscosity, and leakage. Therefore, it is preferable to be able to accurately determine whether one or more of the following abnormalities have occurred. According to the second embodiment, compared to the embodiment in which previously reported head abnormality processing is performed using the amplitude of residual vibration without using the period of residual vibration, it is possible to accurately determine whether one or more of the air bubbles, ink viscosity, and leakage have occurred, thereby improving the possibility of resolving the previously reported head abnormality.

[0150] 3. Variant Each of the embodiments exemplified above can be modified in various ways. Specific examples of modifications that can be applied to each of the embodiments described above are given below. Two or more embodiments arbitrarily selected from the following examples can be merged as appropriate, provided they do not contradict each other.

[0151] 3-1. First variation If the inkjet printer 100 is temporarily unable to connect to the cloud server CS, it stores residual vibration information NI in the memory circuit 160 of the inkjet printer 100. The first modified example is described below.

[0152] 3-1-1. Operation of the first modified example Figure 17 is a flowchart showing the operation of the inkjet system 10 in the first modified example. The flowchart in Figure 17 differs from the flowchart in Figure 11 in that it performs the processes of step SJ52 and step SJ54 between the processes of step SJ2 and step SJ4, but otherwise it is the same. Below, only the differences from the flowchart in Figure 11 will be explained.

[0153] After the processing in step SJ2 is completed, in step SJ52, the control circuit 170 functions as the first transmission unit 173 to determine whether or not it is connected to the cloud server CS. If the result of the determination in step SJ52 is negative, the control circuit 170 stores the residual vibration information NI acquired in step SJ2 in the memory circuit 160 in step SJ54. The memory circuit 160 is an example of a "memory unit". After the processing in step SJ54 is completed, the control circuit 170 executes the processing in step SJ52 again. If the result of the determination in step SJ52 is positive, the control circuit 170 executes the processing in step SJ4. In the processing of step SJ4, if the processing in step SJ54 was executed, the control circuit 170 transmits the residual vibration information NI stored in the memory circuit 160 to the cloud server CS.

[0154] Although not shown in Figure 17, the process in step SJ54 only needs to be executed once. Also, if the result of the determination in step SJ52 is negative multiple times, the control circuit 170 may terminate the series of processes shown in Figure 17. The control circuit 170 then sends information to the processing unit 200 indicating that it was not possible to send the residual vibration information NI to the cloud server CS. The processing unit 200 displays a dialog box on the display device 270 informing the user U that it was not possible to send the residual vibration information NI to the cloud server CS and asking whether or not to have the inkjet printer 100 perform the recording process of the image data Img. If the user U chooses to have the inkjet printer 100 perform the recording process, the inkjet printer 100 performs the recording process.

[0155] Furthermore, as shown in Figure 5, although the inkjet printer 100 has a memory circuit 160 in the printer body, the liquid ejection head HU may also have a memory circuit. In step SJ54, the control circuit 170 may store the residual vibration information NI in the memory circuit of the liquid ejection head HU.

[0156] 3-1-2. Summary of the first variation In the first modified example described above, the inkjet printer 100 is provided with a memory circuit 160, and in step SJ54, if the inkjet printer 100 and the cloud server CS cannot be connected, the first transmission unit 173 stores the residual vibration information NI obtained by the processing in step SJ2 in the memory circuit 160. The inkjet printer 100 and the cloud server CS may be temporarily unable to connect due to reasons such as a temporary interruption of the cloud server CS service or congestion in communication between the inkjet printer 100 and the cloud server CS. According to the first modified example, even if the inkjet printer 100 and the cloud server CS are unable to connect, the residual vibration information NI can be stored in the memory circuit 160, so that the residual vibration information NI can be sent to the cloud server CS when the inkjet printer 100 and the cloud server CS become connected.

[0157] 3-2. Second Variation In each of the embodiments described above, the cloud server CS functioned as the determination unit 303, but the control circuit 170 may also function as the determination unit 303.

[0158] Figure 18 shows the functions of the inkjet printer 100D in the second modified example. The inkjet printer 100D differs from the inkjet printer 100 in that it has a control circuit 170D instead of the control circuit 170. The control circuit 170D differs from the control circuit 170 in that it functions as an acquisition unit 171, a determination unit 303, a maintenance control unit 177, and a notification unit 179. That is, the control circuit 170D functions as a determination unit 303 and performs the processing of step SC4 and step SC6. According to the second modification, the control circuit 170D performs the processing in step SC4, which improves the speed of obtaining the determination information JI compared to the inkjet system 10 in the first embodiment, because it does not need to transmit the residual vibration information NI and receive the determination information JI. For example, the second modification may be applied when a head manufacturer manufactures the printer body in addition to the liquid ejection head HU.

[0159] In the second modified example, the control circuit 170D performs the processing of step SC4 and step SC6, but the control circuit 170D may also transmit residual vibration information NI to the processing device 200, and the control circuit 210 of the processing device 200 may perform the processing of step SC4 and step SC6.

[0160] In the second modified example, after the control circuit 170D has performed the processing in step SC4 and step SC6, the control circuit 170D may transmit the judgment information JI to the cloud server CS. When the cloud server CS receives the judgment information JI, it stores the judgment information JI in the memory circuit 320. The control circuit 170D may also transmit the residual vibration information NI and the judgment information JI to the cloud server CS. When the cloud server CS receives the residual vibration information NI and the judgment information JI, it stores the residual vibration information NI and the judgment information JI in association with each other in the memory circuit 320. The control circuit 170D may also transmit the residual vibration information NI and the judgment information JI to the cloud server CS only if the judgment information JI contains one or more identifiers from the second identifier and the third identifier.

[0161] Furthermore, the inkjet printer 100D in the second modified example does not need to be connected to the cloud server CS. When a service support person from the head manufacturer visits the printer manufacturer or user U, the inkjet printer 100D or processing unit 200 copies the judgment information JI, etc. to a portable storage device brought by the service support person. The portable storage device is, for example, an SSD. SSD is an abbreviation for Solid State Drive. Then, when the service support person returns to the head manufacturer's office, a PC that can connect to the cloud server CS transmits the judgment information JI, etc. stored in the portable storage device to the cloud server CS.

[0162] 3-3. Third Variation In each of the above embodiments, the cloud server CS determines, based on residual vibration information NI, whether a media collision anomaly has occurred, as well as whether a previously reported head anomaly has occurred, but is not limited to this. For example, the cloud server CS may determine only whether a media collision anomaly has occurred based on residual vibration information NI, and may not determine whether a previously reported head anomaly has occurred.

[0163] 3-4. Fourth variation In each of the above embodiments, the cloud server CS acquires residual vibration information NI having 2M individual residual vibration information NEIs, but is not limited to this. The cloud server CS may acquire residual vibration information NI having 2 or more individual residual vibration information NEIs out of the 2M, and determine whether or not a media collision anomaly has occurred based on this residual vibration information NI.

[0164] 3-5. Fifth variation In each of the embodiments described above, if the inkjet printer 100 is connectable to a network NW, the communication device 150 connects to the network NW, but is not limited to this. For example, if the liquid ejection head HU has a communication device, this communication device may communicate with the network NW.

[0165] 3-6. Sixth Variation In each of the above embodiments, the individual residual vibration information NEI is information that associates time information with potential values, but the individual residual vibration information NEI is not limited to information that associates time information with potential values. For example, the individual residual vibration information NEI may be one or both of the following values: a value indicating the amplitude of the residual vibration and a value indicating the period of the residual vibration. For example, the generation circuit 190 identifies the amplitude of the residual vibration from the residual vibration signal NES and outputs the value indicating the identified amplitude as the individual residual vibration information NEI to the control circuit 170.

[0166] 3-7. Seventh Variation In each of the embodiments described above, J is stated to be 9, but it is not limited to this. For example, if the resolution of the image formed by the M nozzles Nz divided into a nozzle row of the liquid discharge head HU is high, increasing the number of J can improve the accuracy of determining whether or not a media collision anomaly has occurred.

[0167] 3-8. Variation 8 In the embodiments described above, a serial-type inkjet printer 100 is exemplified in which the liquid ejection head HU is reciprocated in a direction along the X axis, but the present disclosure is not limited to such embodiments. The inkjet printer 100 may also be a line-type liquid ejection device in which a plurality of nozzles Nz are distributed over the entire width of the medium PP.

[0168] 3-9. Other variations The inkjet printer 100 described above can be used in various devices such as facsimile machines and photocopiers, in addition to devices dedicated to printing. However, the use of the recording device of the present invention is not limited to printing. For example, a recording device that ejects a colorant solution can be used as a manufacturing device for forming color filters for liquid crystal display devices. Also, a recording device that ejects a conductive material solution can be used as a manufacturing device for forming wiring and electrodes for wiring boards. [Explanation of symbols]

[0169] 10... Inkjet system, 20... Recording system, 100, 100D... Inkjet printer, 111... Head chip, 111a... Flow channel substrate, 111b... Pressure chamber substrate, 111c... Nozzle plate, 111d... Vibration absorber, 111e... Diaphragm, 111f... Piezoelectric element, 111f-H... Piezoelectric element to be judged, 111g... Protective plate, 111h... Case, 111i... Wiring board, 112... Drive circuit, 113... Power supply circuit, 114... Drive signal generation circuit, 115... Switching circuit, 116... Connection status specification circuit, 117... Detection circuit, 120... Liquid container, 130... Moving mechanism, 131 ...carriage, 132...endless belt, 140...conveying mechanism, 145...maintenance mechanism, 146...cap, 147...wiper, 150...communication device, 160...memory circuit, 170,170D...control circuit, 171...acquisition unit, 173...first transmission unit, 175...first reception unit, 177...maintenance control unit, 179...notification unit, 190...generation circuit, 200...processing device, 210...control circuit, 220...memory circuit, 230,240...communication device, 260...input device, 270...display device, 290...bus, 300...server, 301...second reception unit, 303...determination unit, 305... Second transmitter, 310…control circuit, 320…memory circuit, 380…communication device, 390…bus, CL…clock signal, CM…control module, CS…cloud server, CV…pressure chamber, CV-H…pressure chamber to be judged, Com, Com-A, Com-B…drive signal, FN…nozzle surface, HU…liquid discharge head, IH…inlet, Img…image data, JI…judgment information, LAT…latch signal, LHa, LHb, LHd, LHs…internal wiring, La, Lb…nozzle row, NEI…individual residual vibration information, NES…residual vibration signal, NI…residual vibration information, NTc…period, NW… Network, Na...Communication channel, Nz...Nozzle, PM1...Control program, PM2...Inkjet program, PM3...Control program, PP...Media, PS...Inspection waveform, PX...Ejection waveform, PlsL, PlsT1, PlsT2...Pulse, R...Reservoir, R1, R2...Space, Ra...Supply channel, Rcd1, Rcd2, Rcd3, Rcd4, Rcd5...Record, SI...Print signal, SLa, SLb, SLs...Connection status specification signal, SWa, SWb, SWs...Switch, Sd...Individual specification signal, Sk1, Sk2, Sk3...Control signal, TSS1, TSS2,TSS3…Control period, Tsig…Period specification signal, Tth1, Tth2, Tth3…Threshold, Tu…Recording period, U…User, V0…Reference potential, VBS…Offset potential, VHS…Maximum potential, VHV…Power supply potential, VHX…Maximum potential, VLS, VLX…Minimum potential, VM…Virtualization program, Vin…Supply drive signal, Vout…Detection signal, Zd…Lower electrode, Zm…Piezoelectric material, Zu…Upper electrode, dCom…Waveform specification signal.

Claims

1. A control method for a liquid dispensing device that dispenses liquid onto a medium, comprising a liquid dispensing head having a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is discharged, An acquisition step to acquire residual vibration information relating to residual vibration in a pressure chamber after applying a voltage to one or more piezoelectric elements among the plurality of piezoelectric elements, A control method characterized by performing a determination step of determining whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid discharge head, based on the residual vibration information.

2. The residual vibration information comprises first individual information relating to residual vibration in a pressure chamber communicating with a target nozzle among the plurality of nozzles, and second individual information relating to J residual vibrations in each of the J pressure chambers communicating with each of the one or more J nozzles continuous with the target nozzle. The control method according to claim 1, characterized in that the determination step determines that the first abnormality has occurred if an abnormality is detected from all of the residual vibrations related to the first individual information and the J residual vibrations related to the second individual information.

3. The control method according to claim 2, characterized in that the determination step determines that the first abnormality has not occurred if an abnormality is detected in the residual vibration relating to the first individual information and no abnormality is detected in any of the J residual vibrations relating to the second individual information.

4. The control method according to claim 2, characterized in that the J nozzles are nine or more nozzles.

5. The control method according to claim 2, characterized in that the determination step further determines, based on the first individual information, whether a second abnormality has occurred, which is an abnormality different from the first abnormality and is an abnormality of the liquid discharge head caused by the liquid discharge head.

6. The control method according to claim 5, characterized in that the determination step determines that the second abnormality has occurred if an abnormality is detected from the residual vibration relating to the first individual information and no abnormality is detected in any of the J residual vibrations relating to the second individual information.

7. The control method according to claim 2, characterized in that the determination step determines whether or not the first abnormality has occurred using the amplitude of residual vibration relating to the first individual information and the second individual information, and without using the period of residual vibration relating to the first individual information and the second individual information.

8. The control method according to claim 7, characterized in that the determination step determines whether or not a second abnormality, which is an abnormality of the liquid discharge head caused by the liquid discharge head, has occurred, using the amplitude and period of residual vibration relating to the first individual information and the second individual information.

9. A server provided outside the aforementioned liquid dispensing device is further used. A transmission step involves transmitting the residual vibration information acquired in the acquisition step from the liquid dispensing device to the server. The process further includes a receiving step of receiving determination information from the server that indicates the determination result obtained in the aforementioned determination step, The control method according to claim 1, characterized in that the server performs the determination step.

10. The liquid dispensing device is provided with a storage unit, The control method according to claim 9, characterized in that, when the liquid dispensing device and the server cannot be connected, the determination step stores the residual vibration information acquired by the acquisition step in the storage unit.

11. The control method according to claim 1, characterized in that the liquid dispensing device performs the determination step.

12. A liquid dispensing device for dispensing liquid onto a medium, comprising: a plurality of piezoelectric elements; a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements; and a liquid dispensing head having a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is discharged, An acquisition unit that acquires residual vibration information relating to residual vibration in a pressure chamber after applying a voltage to one or more piezoelectric elements among the plurality of piezoelectric elements, A determination unit that determines whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid discharge head, based on the residual vibration information, A liquid dispensing device characterized by having the following features.

13. An inkjet system comprising: a liquid ejection device that ejects liquid onto a medium, having a liquid ejection head having a plurality of piezoelectric elements, a plurality of pressure chambers that apply pressure to the liquid inside by driving each of the plurality of piezoelectric elements, and a plurality of nozzles that communicate with each of the plurality of pressure chambers and from which the liquid is ejected; and a server provided outside the liquid ejection device, The aforementioned liquid discharge device is Residual vibration information regarding residual vibration in the pressure chamber after applying a voltage to one or more of the plurality of piezoelectric elements is acquired. The residual vibration information is transmitted from the liquid dispensing device to the server. The aforementioned server is Based on the residual vibration information, it is determined whether or not a first abnormality has occurred, which is an abnormality caused by the medium colliding with the liquid discharge head. An inkjet system characterized by the following features.

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