Liquid discharge device and inspection method of liquid discharge head

Abstract

To reduce a memory amount for storing inspection results of a discharge part.SOLUTION: A liquid discharge device includes: a liquid discharge head in which multiple discharge parts, including a first discharge part configured to discharge liquid, a second discharge part configured to discharge liquid, and a third discharge part configured to discharge liquid, are disposed arranged side by side; an inspection part which inspects the liquid discharge state in each of the discharge parts; and a storage part in which multiple memory regions, including a first memory region, a second memory region, and a third memory region, are disposed in a specific order and which stores the inspection results of the inspection part. Regardless of the order of inspections of the multiple discharge parts by the inspection part, the inspection result of the first discharge part by the inspection part is stored in the first memory region, the inspection result of the second discharge part by the inspection part is stored in the second memory region, and the inspection result of the third discharge part by the inspection part is stored in the third memory region.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and a method for inspecting a liquid ejection head.

Background Art

[0002] A liquid ejection device such as an inkjet printer drives each of a plurality of ejection units included in a liquid ejection head, thereby ejecting a liquid such as ink filled in each ejection unit and forming an image on a medium. However, in a liquid ejection device, ejection abnormalities may occur in which the liquid cannot be normally ejected from the ejection unit. Therefore, conventionally, techniques for inspecting the ejection state in the ejection unit have been proposed. For example, Patent Document 1 discloses a technique for inspecting the ejection state in the ejection unit based on vibrations remaining in the ejection unit after driving the ejection unit by a drive signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, according to the conventional technique, among the plurality of ejection units provided in the liquid ejection device, in order to inspect the ejection unit corresponding to the print data indicating the image to be formed by the liquid ejection device, it is necessary to store the inspection result of the ejection unit and the information for specifying the ejection unit that has become the inspection target among the plurality of ejection units provided in the liquid ejection device in an associated manner.

Means for Solving the Problems

[0005] In order to solve the above problems, a liquid ejection device according to the present invention includes a plurality of ejection units arranged side by side, including a first ejection unit that ejects liquid, a second ejection unit that ejects liquid, and a third ejection unit that ejects liquid; an inspection unit that inspects the ejection state of the liquid in each of the plurality of ejection units; and a storage unit that includes a plurality of memory areas including a first memory area, a second memory area, and a third memory area arranged in a specific order and stores the inspection results by the inspection unit. Regardless of the order of inspection of the plurality of ejection units by the inspection unit, the inspection result of the first ejection unit by the inspection unit is stored in the first memory area, the inspection result of the second ejection unit by the inspection unit is stored in the second memory area, and the inspection result of the third ejection unit by the inspection unit is stored in the third memory area.

[0006] Further, an inspection method for a liquid ejection head according to the present invention is an inspection method for a liquid ejection head in which a plurality of ejection units including a first ejection unit that ejects liquid, a second ejection unit that ejects liquid, and a third ejection unit that ejects liquid are arranged side by side. The method inspects the ejection state of the liquid in each of the plurality of ejection units, and stores the inspection results by the inspection unit in a storage unit that includes a plurality of memory areas including a first memory area, a second memory area, and a third memory area arranged in a specific order. Regardless of the order of inspection of the plurality of ejection units by the inspection unit, the inspection result of the first ejection unit by the inspection unit is stored in the first memory area, the inspection result of the second ejection unit by the inspection unit is stored in the second memory area, and the inspection result of the third ejection unit by the inspection unit is stored in the third memory area.

Brief Description of Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Mode for Carrying Out the Invention

[0008] Hereinafter, embodiments for carrying out the present invention 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 invention, and thus various technically preferable limitations are imposed. However, the scope of the present invention is not limited to these embodiments unless there is a description to specifically limit the present invention in the following description.

[0009] <<A. Embodiment>> In the present embodiment, a liquid ejection device will be described by exemplifying an inkjet printer that ejects ink to form an image on a recording paper PP.

[0010] <<1. Outline of Inkjet Printer>> Hereinafter, with reference to FIGS. 1 to 4, an example of the configuration of the inkjet printer 1 according to the present embodiment will be described.

[0011] FIG. 1 is a functional block diagram showing an example of the configuration of an inkjet printer 1.

[0012] As shown in FIG. 1, print data Img indicating an image to be formed by the inkjet printer 1 is supplied to the inkjet printer 1 from a host computer such as a personal computer or a digital camera. The inkjet printer 1 executes a printing process for forming an image indicated by the print data Img supplied from the host computer on a recording sheet PP.

[0013] As shown in FIG. 1, the inkjet printer 1 includes a control unit 2 that controls each part of the inkjet printer 1, a head unit 3 provided with a discharge unit D that discharges ink, a drive signal generation unit 4 that generates a drive signal Com for driving the discharge unit D, an inspection unit 5 that inspects the ink discharge state in the discharge unit D, a storage unit 6 that stores various information, and a conveyance unit 7 for changing the relative position of the recording sheet PP with respect to the head unit 3. Note that the inkjet printer 1 is an example of a "liquid discharge device", the ink is an example of a "liquid", the head unit 3 is an example of a "liquid discharge head", the inspection unit 5 is an example of an "inspection unit", and the storage unit 6 is an example of a "storage unit".

[0014] In this embodiment, it is assumed that the inkjet printer 1 includes one or more head units 3, one or more drive signal generation units 4 that correspond one-to-one to the one or more head units 3, and one or more inspection units 5 that correspond one-to-one to the one or more head units 3. Specifically, in this embodiment, it is assumed that the inkjet printer 1 includes four head units 3, four drive signal generation units 4 that correspond one-to-one to the four head units 3, and four inspection units 5 that correspond one-to-one to the four head units 3. However, hereinafter, for convenience of explanation, as shown in FIG. 1, one of the four head units 3, one of the four drive signal generation units 4 provided corresponding to one of the four head units 3, and one of the four inspection units 5 provided corresponding to one of the four head units 3 will be described with attention focused thereon.

[0015] The control unit 2 is configured to include one or more CPUs (Central Processing Units). However, the control unit 2 may be provided with a programmable logic device such as an FPGA (field-programmable gate array) instead of or in addition to the CPU.

[0016] The storage unit 6 is configured to include one or both of a volatile memory such as a RAM (Random Access Memory) and a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory), or a PROM (Programmable ROM). Note that, for example, a FIFO (First In First Out) memory can be adopted as the memory provided in the storage unit 6.

[0017] The control unit 2 executes the control program stored in the storage unit 6 and functions as the drive control unit 21 and the inspection management unit 22 by operating according to the control program.

[0018] The drive control unit 21 generates a waveform designation signal dCom. The waveform designation signal dCom is a digital signal that defines the waveform of the drive signal Com. The drive signal Com is an analog signal for driving the ejection unit D. The drive signal generation unit 4 includes a DA conversion circuit and generates a drive signal Com having a waveform defined by the waveform designation signal dCom. In this embodiment, it is assumed that the drive signal Com includes a drive signal Com-A and a drive signal Com-B.

[0019] Also, the drive control unit 21 generates a designation signal SI. The designation signal SI is a digital signal that designates the type of operation of the ejection unit D. Specifically, the designation signal SI is a signal that designates the type of operation of the ejection unit D by designating whether or not to supply and drive the drive signal Com to the ejection unit D.

[0020] When printing processing is executed, the control unit 2 generates signals for controlling the head unit 3 such as the designation signal SI based on the print data Img. Also, when printing processing is executed, the control unit 2 generates signals for controlling the drive signal generation unit 4 such as the waveform designation signal dCom. Also, when printing processing is executed, the control unit 2 generates a signal for controlling the conveyance unit 7. Thereby, in the printing process, the control unit 2 controls the conveyance unit 7 so as to change the relative position of the recording paper PP with respect to the head unit 3, and adjusts the presence or absence of ink ejection from the ejection unit D, the ink ejection timing, etc., so that an image corresponding to the print data Img is formed on the recording paper PP, and controls each part of the inkjet printer 1.

[0021] As shown in FIG. 1, the head unit 3 includes a supply circuit 31, a recording head 32, and a detection circuit 33.

[0022] The recording head 32 includes M ejection units D. Here, the value of M is a natural number satisfying "M ≧ 3". In the following, among the M ejection units D provided in the recording head 32, the m-th ejection unit D may be referred to as ejection unit D[m]. Here, the variable m is a natural number satisfying "1 ≦ m ≦ M". Also, in the following, when a component or signal etc. of the inkjet printer 1 corresponds to the ejection unit D[m] among the M ejection units D, a subscript [m] may be attached to the symbol representing the component or signal etc.

[0023] Based on the designation signal SI, the supply circuit 31 switches whether to supply the drive signal Com to the ejection unit D[m]. In the following, among the drive signals Com, the drive signal Com supplied to the ejection unit D[m] may be referred to as supply drive signal Vin[m]. Also, based on the designation signal SI, the supply circuit 31 switches whether to supply the detection potential signal VX[m] to the detection circuit 33. Here, the detection potential signal VX[m] is a signal indicating the potential of the upper electrode Zu[m] provided on the piezoelectric element PZ[m] included in the ejection unit D[m]. In the following, when the detection potential signal VX[m] is supplied from the ejection unit D[m] to the detection circuit 33, the ejection unit D[m] may be referred to as the ejection unit to be inspected DS. Note that the piezoelectric element PZ[m] and the upper electrode Zu[m] will be described later with reference to FIG. 3.

[0024] Based on the detection potential signal VX[m] supplied from the ejection unit D[m] serving as the ejection unit to be inspected DS via the supply circuit 31, the detection circuit 33 generates a detection signal SK[m]. Specifically, the detection circuit 33 generates the detection signal SK[m] by, for example, amplifying the detection potential signal VX[m] and removing noise components.

[0025] Based on the detection signal SK[m] supplied from the detection circuit 33, the inspection unit 5 inspects the ink ejection state in the ejection unit D[m] driven as the ejection unit to be inspected DS.

[0026] Hereinafter, the process of inspecting the ink ejection state in the ejection unit D[m] by driving the ejection unit D[m] as the ejection unit DS to be inspected is referred to as the ejection state inspection process.

[0027] When the ejection state inspection process is executed, the control unit 2 generates a signal for controlling the head unit 3 such as the designation signal SI. Also, when the ejection state inspection process is executed, the control unit 2 generates a signal for controlling the drive signal generation unit 4 such as the waveform designation signal dCom. Thereby, the control unit 2 drives the ejection unit D[m] as the ejection unit DS to be inspected. Also, when the ejection state inspection process is executed, the control unit 2 controls the head unit 3 so that the detection potential signal VX[m] corresponding to the ejection unit D[m] driven as the ejection unit DS to be inspected is supplied to the detection circuit 33 by generating the designation signal SI. Also, when the ejection state inspection process is executed, the detection circuit 33 generates a detection signal SK[m] based on the detection potential signal VX[m] detected from the ejection unit D[m] driven as the ejection unit DS to be inspected. Then, when the ejection state inspection process is executed, the inspection unit 5 inspects the ink ejection state in the ejection unit D[m] driven as the ejection unit DS to be inspected based on the detection signal SK[m] supplied from the detection circuit 33.

[0028] The inspection unit 5 includes a waveform inspection circuit 51, an inspection result output circuit 52, and an inspection result storage circuit 53.

[0029] The waveform inspection circuit 51 inspects the ink ejection state in the ejection unit DS to be inspected based on the detection signal SK[m]. In other words, the waveform inspection circuit 51 inspects whether or not an ejection abnormality has occurred in the ejection unit DS to be inspected based on the detection signal SK[m]. Then, the waveform inspection circuit 51 generates an inspection result signal DK indicating the result of the inspection. Here, the inspection result signal DK is a signal indicating whether or not an ejection abnormality has occurred in the ejection unit D[m] selected as the ejection unit DS to be inspected (see FIG. 8 described later). Further, the ejection abnormality is a general term for states in which ink cannot be normally ejected from the nozzles N provided in the ejection unit D[m]. For example, the ejection abnormality includes a state in which ink cannot be ejected from the ejection unit D[m], a state in which the ejection unit D[m] ejects an amount of ink different from the ink ejection amount defined by the drive signal Com, and a state in which the ejection unit D[m] ejects ink at a speed different from the ink ejection speed defined by the drive signal Com, and the like.

[0030] The inspection result output circuit 52 generates inspection result individual information DKK[m] based on the inspection result signal DK and the designation signal SI. Here, the inspection result individual information DKK[m] is information including the information indicated by the inspection result signal DK and the ejection unit identification information DD (see FIG. 9 described later). Among these, the ejection unit identification information DD is information for identifying the ejection unit DS to be inspected from among the M ejection units D[1] to D[M] provided in the recording head 32. For example, when the ejection unit D[m] is selected as the ejection unit DS to be inspected, the ejection unit identification information DD indicates the value "m".

[0031] The inspection result storage circuit 53 is configured to include a volatile memory such as a RAM (Random Access Memory).

[0032] When the inspection result output circuit 52 generates the inspection result individual information DKK[m], the generated inspection result individual information DKK[m] is stored in the inspection result storage circuit 53. Further, when the ejection state inspection process is executed a plurality of times and the inspection result output circuit 52 generates a plurality of inspection result individual information DKK[m], the plurality of inspection result individual information DKK[m] is sequentially stored in the inspection result storage circuit 53.

[0033] In the present embodiment, it is assumed that the inspection result storage circuit 53 can store a maximum of Mt pieces of inspection result individual information DKK[m]. In the present embodiment, as an example, it is assumed that the value Mt is a natural number satisfying "1 ≦ Mt < M". However, the present invention is not limited to such a mode. The value Mt may be a natural number satisfying "Mt ≧ M". Hereinafter, the information including one or more pieces of inspection result individual information DKK[m] stored in the inspection result storage circuit 53 is referred to as inspection result temporary storage information DX (see FIG. 9 described later).

[0034] When the acquisition condition described later is satisfied, the inspection result output circuit 52 acquires the inspection result temporary storage information DX including one or more pieces of inspection result individual information DKK[m] stored in the inspection result storage circuit 53 from the inspection result storage circuit 53, and supplies the acquired inspection result temporary storage information DX to the inspection management unit 22. Further, when the acquisition condition described later is satisfied, after the inspection result output circuit 52 acquires the inspection result temporary storage information DX from the inspection result storage circuit 53, the inspection result temporary storage information DX stored in the inspection result storage circuit 53 is deleted from the inspection result storage circuit 53.

[0035] The inspection management unit 22 generates the inspection result information DXX for storage based on the inspection result temporary storage information DX. Here, the inspection result information DXX for storage is information obtained by changing the data format of the inspection result temporary storage information DX (see FIG. 10 described later). Specifically, the inspection result information DXX for storage is information representing the inspection result of the ejection unit D[m] in the ejection state inspection process, and is information represented by the inspection result signal DK generated corresponding to the ejection unit D[m]. Hereinafter, the inspection result information DXX for storage corresponding to the ejection unit D[m] is referred to as inspection result information DXX[m].

[0036] In the storage unit 6, one or more pieces of inspection result information DXX for storage corresponding to some or all of the M ejection units D[1] to D[M] are stored. Hereinafter, the one or more pieces of inspection result information DXX stored in the storage unit 6 are referred to as inspection result storage information DY. When an ejection abnormality occurs in any of the ejection units D[1] to D[M], or when there is an instruction from the user of the inkjet printer 1, the inspection management unit 22 acquires the inspection result storage information DY from the storage unit 6, and causes a display unit (not shown) to display information based on the acquired inspection result storage information DY.

[0037] FIG. 2 is a perspective view showing an example of the schematic internal structure of the inkjet printer 1.

[0038] As shown in FIG. 2, in the present embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when executing the printing process, the inkjet printer 1 transports the recording paper PP in the X1 direction, and reciprocates the head unit 3 in the Y1 direction intersecting the X1 direction and the Y2 direction which is the reverse direction of the Y1 direction, and ejects ink from the ejection unit D[m] to form dots Dt corresponding to the print data Img on the recording paper PP.

[0039] Hereinafter, the X1 direction and the X2 direction which is the opposite direction thereof are collectively referred to as the "X-axis direction", the Y1 direction which intersects the X-axis direction and the Y2 direction which is the opposite direction thereof are collectively referred to as the "Y-axis direction", and the Z1 direction which intersects the X-axis direction and the Y-axis direction and the Z2 direction which is the opposite direction thereof are collectively referred to as the "Z-axis direction". In the present embodiment, as an example, a case where the X-axis direction, the Y-axis direction, and the Z-axis direction are orthogonal to each other will be assumed and described. However, the present invention is not limited to such a mode. The X-axis direction, the Y-axis direction, and the Z-axis direction only need to intersect each other. In the present embodiment, it is assumed that the Z1 direction is the direction in which ink is ejected from the ejection unit D[m].

[0040] As shown in FIG. 2, the inkjet printer 1 according to the present embodiment includes a housing 100 and a carriage 110 that can reciprocate in the Y-axis direction within the housing 100 and mounts four head units 3.

[0041] In the present embodiment, as shown in FIG. 2, it is assumed that the carriage 110 stores four ink cartridges 120 that correspond one-to-one to four colors of ink: cyan, magenta, yellow, and black. Further, in the present embodiment, as described above, it is assumed that the inkjet printer 1 includes four head units 3 that correspond one-to-one to the four ink cartridges 120. Each ejection unit D[m] receives ink supply from an ink cartridge 120 corresponding to the head unit 3 in which the ejection unit D[m] is provided. Thereby, each ejection unit D[m] can fill the supplied ink therein and eject the ink filled inside the ejection unit D[m] from a nozzle N provided in the ejection unit D[m]. Note that the ink cartridge 120 may be provided outside the carriage 110.

[0042] Also, as described above, the inkjet printer 1 according to the present embodiment includes a conveyance unit 7. As shown in FIG. 2, the conveyance unit 7 includes a carriage conveyance mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 76 that supports the carriage 110 so as to be reciprocable in the Y-axis direction, a medium conveyance mechanism 73 for conveying the recording paper PP, and a platen 75 provided in the Z1 direction of the carriage 110. Therefore, when the printing process is executed, the conveyance unit 7 reciprocates the head unit 3 together with the carriage 110 along the carriage guide shaft 76 in the Y-axis direction by the carriage conveyance mechanism 71, and conveys the recording paper PP on the platen 75 in the X1 direction by the medium conveyance mechanism 73, thereby changing the relative position of the recording paper PP with respect to the head unit 3 and enabling the ink to land on the entire recording paper PP.

[0043] FIG. 3 is a schematic partial cross-sectional view of the recording head 32 cut so as to include the discharge portion D[m].

[0044] As shown in FIG. 3, the ejection unit D[m] includes a piezoelectric element PZ[m], a cavity CV filled with ink therein, a nozzle N communicating with the cavity CV, and a diaphragm 321. When the piezoelectric element PZ[m] is driven by a supply drive signal Vin[m], the ejection unit D[m] ejects the ink in the cavity CV from the nozzle N. The cavity CV is a space partitioned by a cavity plate 324, a nozzle plate 323 in which the nozzle N is formed, and the diaphragm 321. The cavity CV communicates with a reservoir 325 via an ink supply port 326. The reservoir 325 communicates with an ink cartridge 120 corresponding to the ejection unit D[m] via an ink intake port 327. The piezoelectric element PZ[m] has an upper electrode Zu[m], a lower electrode Zd[m], and a piezoelectric body Zm[m] provided between the upper electrode Zu[m] and the lower electrode Zd[m]. The lower electrode Zd[m] is electrically connected to a power supply line Ld set to a predetermined potential VBS. When a supply drive signal Vin[m] is supplied to the upper electrode Zu[m] and a voltage is applied between the upper electrode Zu[m] and the lower electrode Zd[m], the piezoelectric element PZ[m] is displaced in the Z1 direction or the Z2 direction according to the applied voltage, and as a result, the piezoelectric element PZ[m] vibrates. The lower electrode Zd[m] is joined to the diaphragm 321. Therefore, when the piezoelectric element PZ[m] is driven by the supply drive signal Vin[m] and vibrates, the diaphragm 321 also vibrates. Then, the vibration of the diaphragm 321 changes the volume of the cavity CV and the pressure in the cavity CV, and the ink filled in the cavity CV is ejected from the nozzle N.

[0045] FIG. 4 is an explanatory diagram for explaining an example of the arrangement of four head units 3 included in the inkjet printer 1 and a total of 4M nozzles N provided in the four head units 3 when the inkjet printer 1 is viewed in plan from the Z1 direction toward the Z2 direction. As shown in FIG. 4, a nozzle row Ln is provided in the head unit 3. Here, the nozzle row Ln is a plurality of nozzles N provided so as to extend in a row in a predetermined direction.

[0046] In the present embodiment, as an example, it is assumed that each nozzle row Ln is composed of M nozzles N arranged so as to extend in the X-axis direction. Specifically, in the present embodiment, it is assumed that M nozzles N corresponding to M discharge units D[1] to D[M] are arranged in order from the X1 direction to the X2 direction. That is, in the present embodiment, it is assumed that the nozzle N included in the discharge unit D[m0] is arranged adjacent to the nozzle N included in the discharge unit D[m0 - 1] in the X2 direction of the nozzle N included in the discharge unit D[m0 - 1], and the nozzle N included in the discharge unit D[m0 + 1] is arranged adjacent to the nozzle N included in the discharge unit D[m0] in the X2 direction of the nozzle N included in the discharge unit D[m0]. In other words, in the present embodiment, it is assumed that the discharge unit D[m0] is arranged adjacent to the discharge unit D[m0 - 1] in the X2 direction of the discharge unit D[m0 - 1], and the discharge unit D[m0 + 1] is arranged adjacent to the discharge unit D[m0] in the X2 direction of the discharge unit D[m0]. Here, the variable m0 is a natural number satisfying "2 ≤ m0 ≤ M - 1".

[0047] Note that the present invention is not limited to the embodiment shown in FIG. 4. For example, the head unit 3 may be provided with two nozzle rows Ln. In this case, among the M ejection parts D[1] to D[M] included in the head unit 3, the nozzles N included in the odd-numbered ejection parts D[ma] belong to one of the two nozzle rows Ln included in the head unit 3, and the nozzles N included in the even-numbered ejection parts D[mb] may be arranged so as to belong to the other nozzle row Ln among the two nozzle rows Ln included in the head unit 3. And, the ejection part D[ma] having the nozzle N belonging to one nozzle row Ln is arranged adjacent to the ejection part D[ma-2] in the X2 direction of the ejection part D[ma-2] having the nozzle N belonging to one nozzle row Ln, and the ejection part D[ma+2] having the nozzle N belonging to one nozzle row Ln is arranged adjacent to the ejection part D[ma] in the X2 direction of the ejection part D[ma] having the nozzle N belonging to one nozzle row Ln, the ejection part D[mb] having the nozzle N belonging to the other nozzle row Ln is arranged adjacent to the ejection part D[mb-2] in the X2 direction of the ejection part D[mb-2] having the nozzle N belonging to the other nozzle row Ln, and the ejection part D[mb+2] having the nozzle N belonging to the other nozzle row Ln is arranged adjacent to the ejection part D[mb] in the X2 direction of the ejection part D[mb] having the nozzle N belonging to the other nozzle row Ln. Here, the variable ma is an odd number satisfying "3 ≦ ma ≦ M", and the variable mb is an even number satisfying "4 ≦ mb ≦ M".

[0048] <<2. Outline of Head Unit>> Hereinafter, the outline of the head unit 3 will be described with reference to FIGS. 5 to 7.

[0049] FIG. 5 is a block diagram showing an example of the configuration of the head unit 3.

[0050] As shown in FIG. 5, the head unit 3 includes a supply circuit 31, a recording head 32, and a detection circuit 33. The head unit 3 also includes a wiring La to which a drive signal Com-A is supplied from the drive signal generation unit 4, a wiring Lb to which a drive signal Com-B is supplied from the drive signal generation unit 4, a power supply line Ld set to the potential VBS, and a wiring Ls for supplying a detection potential signal VX[m] to the detection circuit 33.

[0051] The supply circuit 31 includes M ejection units D[1] to D[M], M switches Wa[1] to Wa[M] corresponding one-to-one to the M ejection units D[1] to D[M], M switches Wb[1] to Wb[M] corresponding one-to-one to the M ejection units D[1] to D[M], M switches Ws[1] to Ws[M] corresponding one-to-one to the M ejection units D[1] to D[M], and a connection state specifying circuit 310 for specifying the connection state of each switch.

[0052] Based on the specifying signal SI, latch signal LAT, change signal CH, and period specifying signal Tsig supplied from the control unit 2, the connection state specifying circuit 310 generates a connection state specifying signal Qa[m] for specifying the on / off of the switch Wa[m], a connection state specifying signal Qb[m] for specifying the on / off of the switch Wb[m], and a connection state specifying signal Qs[m] for specifying the on / off of the switch Ws[m].

[0053] Based on the connection state specifying signal Qa[m], the switch Wa[m] switches the conduction and non-conduction between the wiring La and the upper electrode Zu[m] of the piezoelectric element PZ[m]. In this embodiment, the switch Wa[m] turns on when the connection state specifying signal Qa[m] is at a high level and turns off when it is at a low level. When the switch Wa[m] is on, the drive signal Com-A supplied to the wiring La is supplied as a supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection unit D[m]. Switch Wb[m] switches between conduction and non-conduction of wiring Lb and the upper electrode Zu[m] of piezoelectric element PZ[m] based on the connection state designation signal Qb[m]. In the present embodiment, switch Wb[m] turns on when the connection state designation signal Qb[m] is at a high level and turns off when it is at a low level. When switch Wb[m] is on, the drive signal Com-B supplied to wiring Lb is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection unit D[m]. Switch Ws[m] switches between conduction and non-conduction of wiring Ls and the upper electrode Zu[m] of piezoelectric element PZ[m] based on the connection state designation signal Qs[m]. In the present embodiment, switch Ws[m] turns on when the connection state designation signal Qs[m] is at a high level and turns off when it is at a low level. When switch Ws[m] is on, the potential of the upper electrode Zu[m] provided in the ejection unit D[m] is supplied as the detection potential signal VX[m] to the detection circuit 33 via wiring Ls.

[0054] In the present embodiment, the detection circuit 33 generates a detection signal SK[m] having a waveform corresponding to the waveform of the detection potential signal VX[m] based on the detection potential signal VX[m] supplied from the wiring Ls. Specifically, the detection circuit 33 generates a signal obtained by amplifying the detection potential signal VX[m] and removing noise components from the detection potential signal VX[m], and outputs the generated signal as the detection signal SK[m].

[0055] When the inkjet printer 1 executes printing processing or ejection state inspection processing, a plurality of unit periods TP are set as the operation period of the inkjet printer 1. The inkjet printer 1 can drive each ejection unit D for printing processing or ejection state inspection processing in each unit period TP.

[0056] FIG. 6 is a timing chart showing an example of various signals such as the drive signal Com supplied to the head unit 3 in each of the plurality of unit periods TP.

[0057] As shown in FIG. 6, the control unit 2 outputs a latch signal LAT having a plurality of pulse PLLs. Thereby, the control unit 2 defines a unit period TP as a period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL.

[0058] Further, the control unit 2 outputs a change signal CH having a pulse PLC in the unit period TP. Thereby, the control unit 2 divides the unit period TP into a drive period TQ1 from the rising edge of the pulse PLL to the rising edge of the pulse PLC and a drive period TQ2 from the rising edge of the pulse PLC to the rising edge of the pulse PLL.

[0059] The control unit 2 outputs a period designation signal Tsig having a pulse PLT1 and a pulse PLT2 in the unit period TP. Then, the control unit 2 divides the unit period TP into a control period TS1 from the rising edge of the pulse PLL to the rising edge of the pulse PLT1, a control period TS2 from the rising edge of the pulse PLT1 to the rising edge of the pulse PLT2, and a control period TS3 from the rising edge of the pulse PLT2 to the rising edge of the pulse PLL.

[0060] As shown in FIG. 5, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] that correspond one-to-one to the M ejection units D[1] to D[M]. The individual designation signal Sd[m] designates the driving mode of the ejection unit D[m] in each unit period TP when the inkjet printer 1 executes a printing process or a ejection state inspection process. The control unit 2 supplies a designation signal SI including M individual designation signals Sd[1] to Sd[M] to the connection state designation circuit 310 in synchronization with the clock signal CL prior to each unit period TP. Then, the connection state designation circuit 310 generates a connection state designation signal Qa[m], a connection state designation signal Qb[m], and a connection state designation signal Qs[m] based on the individual designation signal Sd[m] in each unit period TP.

[0061] In the present embodiment, the individual designation signal Sd[m] can take any one of five values, namely, the value "1" that designates the ejection unit D[m] as the large dot formation ejection unit DP-1, the value "2" that designates the ejection unit D[m] as the medium dot formation ejection unit DP-2, the value "3" that designates the ejection unit D[m] as the small dot formation ejection unit DP-3, the value "4" that designates the ejection unit D[m] as the non-dot formation ejection unit DP-4, and the value "5" that designates the ejection unit D[m] as the ejection unit DS to be inspected (see FIG. 7 described later).

[0062] Here, the large dot formation ejection unit DP-1 is the ejection unit D that forms large dots in the unit period TP. The medium dot formation ejection unit DP-2 is the ejection unit D that forms medium dots in the unit period TP. The small dot formation ejection unit DP-3 is the ejection unit D that forms small dots in the unit period TP. The non-dot formation ejection unit DP-4 is the ejection unit D that does not form dots in the unit period TP and is an ejection unit D other than the ejection unit DS to be inspected. The ejection unit DS to be inspected is, as described above, the ejection unit D that is the target of the ejection state inspection process in the unit period TP.

[0063] As shown in FIG. 6, the drive signal Com-A has a waveform PP1 and a waveform PP2 provided in each unit period TP. Here, the waveform PP1 is a waveform that returns to the reference potential V0 via a potential VL1 lower than the reference potential V0 and a potential VH1 higher than the reference potential V0 in each unit period TP. When the supply drive signal Vin[m] having the waveform PP1 is supplied to the ejection unit D[m], the waveform PP1 is determined so that the ink corresponding to the ink amount ξ1 is ejected from the ejection unit D[m]. Further, the waveform PP2 is a waveform that returns to the reference potential V0 via a potential VL2 lower than the reference potential V0 and a potential VH2 higher than the reference potential V0 in each unit period TP. When the supply drive signal Vin[m] having the waveform PP2 is supplied to the ejection unit D[m], the waveform PP2 is determined so that the ink corresponding to the ink amount ξ2 is ejected from the ejection unit D[m]. In the present embodiment, it is assumed that the large dot is formed from the ink having the total amount of the ink amounts ξ1 and ξ2, the medium dot is formed from the ink having the ink amount ξ1, and the small dot is formed from the ink having the ink amount ξ2.

[0064] In the present embodiment, as an example, when the potential of the supply drive signal Vin[m] supplied to the ejection unit D[m] is high, it is assumed that the volume of the cavity CV provided in the ejection unit D[m] is smaller than that in the case of the low potential. Therefore, when the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PP1 or the waveform PP2, the ink in the ejection unit D[m] is ejected from the nozzle N as the potential of the supply drive signal Vin[m] changes from the low potential to the high potential.

[0065] As shown in FIG. 6, the drive signal Com-B has a waveform PS provided in each unit period TP. Here, the waveform PS changes from the reference potential V0 to a potential VS1 higher than the reference potential V0 and then to a potential VS2 lower than the reference potential V0 during the control period TS1 in each unit period TP, maintains the potential VS2 during the control period TS2 in each unit period TP, and returns from the potential VS2 to the reference potential V0 during the control period TS3 in each unit period TP. In the present embodiment, the waveform PS is provided so that ink is not ejected from the ejection unit D[m] even when the ejection unit D[m] is driven by the drive signal Com-B.

[0066] FIG. 7 is an explanatory diagram showing an example of the operation of the connection state specifying circuit 310.

[0067] As shown in FIG. 7, when the individual designation signal Sd[m] indicates the value "1" that designates the ejection unit D[m] as the large dot forming ejection unit DP-1 in the unit period TP, the connection state specifying circuit 310 maintains the connection state specifying signal Qa[m] at a high level throughout the unit period TP. In this case, the switch Wa[m] is turned on throughout the unit period TP. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveforms PP1 and PP2 in the unit period TP, and ejects ink in a total amount of the ink amount ξ1 and the ink amount ξ2, which corresponds to a large dot. Further, when the individual designation signal Sd[m] indicates the value "2" that designates the ejection unit D[m] as the medium dot forming ejection unit DP-2 in the unit period TP, the connection state specifying circuit 310 maintains the connection state specifying signal Qa[m] at a high level during the drive period TQ1. In this case, the switch Wa[m] is turned on during the drive period TQ1. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PP1 during the drive period TQ1, and ejects ink in an amount of the ink amount ξ1, which corresponds to a medium dot. Further, when the individual designation signal Sd[m] indicates the value "3" that designates the ejection unit D[m] as the small dot formation ejection unit DP-3 in the unit period TP, the connection state designation circuit 310 maintains the connection state designation signal Qa[m] at a high level during the drive period TQ2. In this case, the switch Wa[m] turns on during the drive period TQ2. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PP2 during the drive period TQ2, and ejects ink in an amount ξ2, which corresponds to a small dot. Also, when the individual designation signal Sd[m] indicates the value "4" that designates the ejection unit D[m] as the non-dot formation ejection unit DP-4 in the unit period TP, the connection state designation circuit 310 maintains the connection state designation signal Qa[m], the connection state designation signal Qb[m], and the connection state designation signal Qs[m] at a low level throughout the unit period TP. In this case, the switch Wa[m], the switch Wb[m], and the switch Ws[m] turn off throughout the unit period TP. Therefore, the ejection unit D[m] is not driven by the supply drive signal Vin[m] in the unit period TP and does not eject ink.

[0068] Also, when the individual designation signal Sd[m] indicates the value "5" that designates the discharge unit D[m] as the discharge unit to be inspected DS in the unit period TP, the connection state designation circuit 310 maintains the connection state designation signal Qb[m] at a high level in the control period TS1 and the control period TS3, and maintains the connection state designation signal Qs[m] at a high level in the control period TS2. In this case, the switch Wb[m] is turned on in the control period TS1 and the control period TS3, and the switch Ws[m] is turned on in the control period TS2. Therefore, the discharge unit D[m] is driven and vibrated by the supply drive signal Vin[m] having the waveform PS in the control period TS1. Then, in the control period TS2, the detection circuit 33 detects the potential of the upper electrode Zu[m] that changes according to the vibration remaining in the discharge unit D[m] as the detection potential signal VX[m] via the switch Ws[m]. Note that the waveform of the detection potential signal VX[m] detected from the discharge unit D[m] in the control period TS2 indicates the waveform of the vibration remaining in the discharge unit D[m] in the control period TS2. And the waveform of the detection signal SK[m] generated based on the detection potential signal VX[m] detected from the discharge unit D[m] in the control period TS2 indicates the waveform of the vibration remaining in the discharge unit D[m] in the control period TS2.

[0069] <<3. Inspection Unit>> Hereinafter, the outline of the inspection unit 5 and the inspection management unit 22 will be described with reference to FIGS. 8 and 9.

[0070] As described above, the inspection unit 5 includes a waveform inspection circuit 51, an inspection result output circuit 52, and an inspection result storage circuit 53. Among these, the waveform inspection circuit 51 inspects the ink discharge state in the discharge unit D[m] designated as the discharge unit to be inspected DS based on the detection signal SK[m] supplied from the detection circuit 33.

[0071] Specifically, the waveform inspection circuit 51 measures the period TC[m] of the detection signal SK[m]. Then, the waveform inspection circuit 51 inspects the ink discharge state in the discharge unit D[m] based on the measured period TC[m], and generates an inspection result signal DK indicating the result of the inspection.

[0072] FIG. 8 is an explanatory diagram for explaining an example of generation of an inspection result signal DK in the waveform inspection circuit 51.

[0073] As shown in FIG. 8, the waveform inspection circuit 51 inspects the ink ejection state in the ejection unit D[m] by comparing the period TC[m] with part or all of the threshold values Tth1, Tth2, and Tth3, and generates an inspection result signal DK indicating the result of the inspection. In this embodiment, as an example, a case where the inspection result signal DK indicates a 2-bit value is assumed.

[0074] The threshold value Tth1 is a fixed value for indicating the boundary between the period TC[m] of the residual vibration generated in the ejection unit D[m] when the ejection state of the ejection unit D[m] is normal and the period TC[m] of the residual vibration generated in the ejection unit D[m] when air bubbles are mixed into the cavity CV of the ejection unit D[m]. The threshold value Tth2 is a value larger than the threshold value Tth1, and is a fixed value for indicating the boundary between the period TC[m] of the residual vibration generated in the ejection unit D[m] when the ejection state of the ejection unit D[m] is normal and the period TC[m] of the residual vibration generated in the ejection unit D[m] when foreign matter adheres near the nozzle N of the ejection unit D[m]. The threshold value Tth3 is a value larger than the threshold value Tth2, and is a fixed value for indicating the boundary between the period TC[m] of the residual vibration generated in the ejection unit D[m] when foreign matter adheres near the nozzle N of the ejection unit D[m] and the period TC[m] of the residual vibration generated in the ejection unit D[m] when the ink in the cavity CV of the ejection unit D[m] thickens.

[0075] In this embodiment, when the period TC[m] satisfies "Tth1 ≤ TC[m] ≤ Tth2", the waveform inspection circuit 51 regards the ink ejection state in the ejection unit D[m] as normal, and sets a value "00" indicating that the ink ejection state in the ejection unit D[m] is normal for the inspection result signal DK. Further, when the period TC[m] satisfies "TC[m] < Tth1", the waveform inspection circuit 51 determines that a discharge abnormality due to bubbles has occurred in the discharge unit D[m], and sets a value "01" indicating that a discharge abnormality due to bubbles has occurred in the discharge unit D[m] in the inspection result signal DK. Also, when the period TC[m] satisfies "Tth2 < TC[m] ≤ Tth3", the waveform inspection circuit 51 determines that a discharge abnormality due to foreign matter adhesion has occurred in the discharge unit D[m], and sets a value "10" indicating that a discharge abnormality due to foreign matter adhesion has occurred in the discharge unit D[m] in the inspection result signal DK. Further, when the period TC[m] satisfies "Tth3 < TC[m]", the waveform inspection circuit 51 determines that a discharge abnormality due to thickening has occurred in the discharge unit D[m], and sets a value "11" indicating that a discharge abnormality due to thickening has occurred in the discharge unit D[m] in the inspection result signal DK.

[0076] Thus, in this embodiment, the inspection result signal DK is a 2-bit signal having only information indicating the inspection result of the ink discharge state in the discharge unit D[m], and does not include the discharge unit identification information DD for specifying the discharge unit D[m] that is the target of the discharge state inspection process among the M discharge units D[1] to D[M].

[0077] As described above, the inspection result output circuit 52 generates the inspection result individual information DKK[m] based on the inspection result signal DK and the designation signal SI.

[0078] Specifically, the inspection result output circuit 52 identifies the individual designation signal Sd[m] indicating the value "5" that designates the discharge unit D[m] as the inspection target discharge unit DS from among the M individual designation signals Sd[1] to Sd[M] included in the designation signal SI. Then, based on the arrangement position of the designated signal SI in the individually designated signal Sd[m] that has been specified, the inspection result output circuit 52 generates ejection unit identification information DD indicating the value "m" corresponding to the individually designated signal Sd[m]. In this embodiment, it is assumed that the M individually designated signals Sd[1] to Sd[M] included in the designated signal SI are arranged in order from the individually designated signal Sd[1] to the individually designated signal Sd[M]. That is, in this embodiment, it is assumed that the individually designated signal Sd[m] is arranged at the m-th position among the individually designated signals Sd[1] to Sd[M] included in the designated signal SI. After that, the inspection result output circuit 52 generates inspection result individual information DKK[m] including the generated ejection unit identification information DD and the inspection result signal DK acquired from the waveform inspection circuit 51. Then, the inspection result output circuit 52 assigns an inspection ID, which will be described later, to the generated inspection result individual information DKK[m], and stores it in the inspection result storage circuit 53 as inspection result temporary storage information DX.

[0079] FIG. 9 is an explanatory diagram for explaining an example of the data configuration of the inspection result temporary storage information DX.

[0080] As shown in FIG. 9, the inspection result temporary storage information DX has one or more records that correspond one-to-one with one or more ejection state inspection processes executed by the inkjet printer 1 during a predetermined inspection period. Each record of the inspection result temporary storage information DX includes an inspection ID and inspection result individual information DKK[m].

[0081] Here, the inspection period is, for example, a period having a time length that is two times or more the unit period TP and Mt times or less the unit period TP. However, the present invention is not limited to such a mode. The inspection period may be, for example, a period during which an image based on the print data Img is formed on the recording paper PP, or a period during which images based on the print data Img are formed on a plurality of recording papers PP. Also, the inspection ID is identification information for identifying each ejection state inspection process from among one or more ejection state inspection processes executed during the inspection period. In addition, as described above, the inspection result individual information DKK[m] is information including the discharge unit identification information DD for identifying the discharge unit D[m] and the inspection result signal DK.

[0082] When a predetermined acquisition condition is satisfied, the inspection result output circuit 52 acquires the inspection result temporary storage information DX from the inspection result storage circuit 53, and supplies the acquired inspection result temporary storage information DX to the inspection management unit 22. Here, the case where the acquisition condition is satisfied means that, for example, one or both of the conditions that the inspection period has ended and that the number of records of the inspection result temporary storage information DX has reached Mt are satisfied.

[0083] As described above, the inspection management unit 22 generates one or more storage inspection result information DXX based on the inspection result temporary storage information DX supplied from the inspection result output circuit 52. Then, the inspection management unit 22 stores the generated one or more storage inspection result information DXX in the storage unit 6 as the inspection result storage information DY.

[0084] In the present embodiment, as described above, the storage inspection result information DXX[m] is information representing the inspection result of the discharge unit D[m] in the discharge state inspection process, and is information represented by the inspection result signal DK generated corresponding to the discharge unit D[m]. Specifically, in the present embodiment, it is assumed that the storage inspection result information DXX[m] does not include the discharge unit identification information DD. More specifically, in the present embodiment, it is assumed that the storage inspection result information DXX[m] is information indicating only the 2-bit value represented by the inspection result signal DK corresponding to the discharge unit D[m].

[0085] FIG. 10 is an explanatory diagram for explaining an example of a memory area on the storage unit 6 in which the inspection result storage information DY is stored.

[0086] As shown in FIG. 10, the inspection result storage information DY is stored in the inspection result storage area AR provided in the storage unit 6.

[0087] The inspection result storage area AR is a memory area composed of (R * S) individual storage areas ARR arranged in R rows and S columns. In this embodiment, the value R is a natural number satisfying "3 ≤ R < M", and the value S is a natural number satisfying "3 ≤ S < M".

[0088] The individual storage area ARR is a memory area for storing the storage inspection result information DXX. In this embodiment, as described above, it is assumed that the storage inspection result information DXX indicates a 2-bit value. Therefore, in this embodiment, as an example, it is assumed that each individual storage area ARR is a 2-bit memory area.

[0089] Also, in this embodiment, it is assumed that the inspection result storage area AR is configured to include M or more individual storage areas ARR. Specifically, in this embodiment, it is assumed that the values R and S satisfy "R * S ≥ M". Note that the values R and S may be values that satisfy "R * S = M". And in this embodiment, the inspection result storage information DY is composed of one or more storage inspection result information DXX stored in the M individual storage areas ARR included in the inspection result storage area AR.

[0090] Hereinafter, among the (R * S) individual storage areas ARR arranged in the inspection result storage area AR, the individual storage area ARR located in the r-th row and s-th column is referred to as the individual storage area ARR[r][s]. Here, the variable r is a natural number satisfying "1 ≤ r ≤ R", and the variable s is a natural number satisfying "1 ≤ s ≤ S".

[0091] The inspection management unit 22 stores some or all of the storage inspection result information DXX[1] to DXX[M] in a specific order for M individual storage areas ARR among the individual storage areas ARR[1][1] to ARR[R][S]. In this embodiment, as an example, it is assumed that the inspection management unit 22 stores the storage inspection result information DXX[(s - 1) * R + r] in the individual storage area ARR[r][s].

[0092] That is, in the present embodiment, the inspection management unit 22 stores the storage inspection result information DXX[r] in the individual storage area ARR[r][1]. Specifically, the inspection management unit 22 stores the storage inspection result information DXX[1] in the individual storage area ARR[1][1], stores the storage inspection result information DXX[2] in the individual storage area ARR[2][1], and stores the storage inspection result information DXX[R] in the individual storage area ARR[R][1]. In addition, the inspection management unit 22 stores the storage inspection result information DXX[R+r] in the individual storage area ARR[r][2]. Specifically, the inspection management unit 22 stores the storage inspection result information DXX[R+1] in the individual storage area ARR[1][2], stores the storage inspection result information DXX[R+2] in the individual storage area ARR[2][2], and stores the storage inspection result information DXX[2*R] in the individual storage area ARR[R][2]. In addition, the inspection management unit 22 stores the storage inspection result information DXX[(s-1)R+r] in the individual storage area ARR[r][s]. Specifically, the inspection management unit 22 stores the storage inspection result information DXX[(s-1)R+1] in the individual storage area ARR[1][s], stores the storage inspection result information DXX[(s-1)R+2] in the individual storage area ARR[2][s], and stores the storage inspection result information DXX[s*R] in the individual storage area ARR[R][s].

[0093] That is, in the present embodiment, when the inspection management unit 22 stores the inspection result information for storage DXX[mx] in the individual storage area ARR[rx][s], it stores the inspection result information for storage DXX[mx + 1] in the individual storage area ARR[rx + 1][s], and stores the inspection result information for storage DXX[mx + 2] in the individual storage area ARR[rx + 2][s]. Here, the variable rx is a natural number satisfying "1 ≦ rx ≦ R - 2", and the variable mx is a natural number satisfying "1 ≦ mx ≦ M - 2". In this case, the individual storage area ARR[rx][s] is an example of the "first memory area", the individual storage area ARR[rx + 1][s] is an example of the "second memory area", the individual storage area ARR[rx + 2][s] is an example of the "third memory area", the discharge unit D[mx] is an example of the "first discharge unit", the discharge unit D[mx + 1] is an example of the "second discharge unit", and the discharge unit D[mx + 2] is an example of the "third discharge unit".

[0094] Also, in the present embodiment, when the inspection management unit 22 stores the inspection result information for storage DXX[my] in the individual storage area ARR[r][sy], it stores the inspection result information for storage DXX[my + R] in the individual storage area ARR[r][sy + 1], and stores the inspection result information for storage DXX[my + 2*R] in the individual storage area ARR[r][sy + 2]. Here, the variable sy is a natural number satisfying "1 ≦ sx ≦ S - 2", and the variable my is a natural number satisfying "1 ≦ my ≦ M - 2*R". In this case, the individual storage area ARR[r][sy] is another example of the "first memory area", the individual storage area ARR[r][sy + 1] is another example of the "second memory area", the individual storage area ARR[r][sy + 2] is another example of the "third memory area", the discharge unit D[my] is another example of the "first discharge unit", the discharge unit D[my + R] is another example of the "second discharge unit", and the discharge unit D[my + 2*R] is another example of the "third discharge unit".

[0095] As described above, in the present embodiment, the inspection management unit 22 generates storage inspection result information DXX[m] that indicates only a 2-bit value representing the inspection result of the ejection unit D[m] in the ejection state inspection process. Then, in the present embodiment, the inspection management unit 22 stores the storage inspection result information DXX[(s - 1)*R + r] in the individual storage area ARR[r][s] among the inspection result storage areas AR of the storage unit 6. For this reason, in the present embodiment, the inspection management unit 22 can identify that the storage inspection result information DXX[(s - 1)*R + r] stored in the individual storage area ARR[r][s] is information indicating the inspection result of the ejection unit D[(s - 1)*R + r] in the ejection state inspection process, from the value "r" indicating the row where the individual storage area ARR[r][s] is arranged and the value "s" indicating the column where the individual storage area ARR[r][s] is arranged, which are the locations of the individual storage area ARR[r][s] in the inspection result storage area AR. That is, in the present embodiment, the inspection management unit 22 can identify information indicating the inspection result of the ejection unit D[m] in the ejection state inspection process, without storing the ejection unit identification information DD in the inspection result storage area AR. That is, according to the present embodiment, compared with the mode of storing in association the information indicating the inspection result of the ejection unit D[m] in the ejection state inspection process and the ejection unit identification information DD, which is information for identifying the ejection unit D[m] from among the M ejection units D[1] to D[M], in the inspection result storage area AR of the storage unit 6, it is possible to reduce the memory amount of the inspection result storage area AR.

[0096] Also, according to the present embodiment, the inspection management unit 22 stores part or all of the storage inspection result information DXX[1] to DXX[M] in a specific order in M out of the individual storage areas ARR[1][1] to ARR[R][S] included in the inspection result storage area AR. That is, according to the present embodiment, the inspection management unit 22 stores the inspection result of the ejection unit D[(s - 1)*R + r] in the ejection state inspection process in the individual storage area ARR[r][s]. Therefore, according to the present embodiment, compared with the mode of storing part or all of the storage inspection result information DXX[1] to DXX[M] in the individual storage areas ARR[1][1] to ARR[R][S] included in the inspection result storage area AR in a random order, the inspection management unit 22 can shorten the time to access the individual storage area ARR in which the inspection result of the desired ejection unit D[m] is stored. Thereby, according to the present embodiment, it is possible to realize speeding up the reading of the inspection result of the ejection unit D[m] from the storage unit 6.

[0097] <<4. Conclusion of the Embodiment>> As described above, the inkjet printer 1 according to the present embodiment includes a head unit 3 in which a plurality of ejection units D including an ejection unit D[mx] that ejects ink, an ejection unit D[mx + 1] that ejects ink, and an ejection unit D[mx + 2] that ejects ink are arranged side by side, an inspection unit 5 that inspects the ink ejection state in the ejection unit D, and a storage unit 6 that stores a plurality of individual storage areas ARR including an individual storage area ARR[rx][s], an individual storage area ARR[rx + 1][s], and an individual storage area ARR[rx + 2][s] arranged in a specific order and stores the inspection results by the inspection unit 5. Regardless of the order of inspection of the plurality of ejection units D by the inspection unit 5, the inspection result of the ejection unit D[mx] by the inspection unit 5 is stored in the individual storage area ARR[rx][s], the inspection result of the ejection unit D[mx + 1] by the inspection unit 5 is stored in the individual storage area ARR[rx + 1][s], and the inspection result of the ejection unit D[mx + 2] by the inspection unit 5 is stored in the individual storage area ARR[rx + 2][s].

[0098] As described above, according to the present embodiment, for each of the plurality of individual storage areas ARR, the inspection result of the discharge unit D corresponding to each individual storage area ARR is stored. That is, according to the present embodiment, the discharge unit D corresponding to the inspection result stored in the individual storage area ARR can be specified from the arrangement location of the individual storage area ARR in the storage unit 6. Therefore, according to the present embodiment, it is not necessary to store the discharge unit identification information DD for specifying the discharge unit D to be inspected by the inspection unit 5 in the storage unit 6. That is, according to the present embodiment, compared with the mode of storing the discharge unit identification information DD for specifying the discharge unit D to be inspected by the inspection unit 5 in the storage unit 6, the memory amount for storing the inspection result of the discharge unit D in the storage unit 6 can be reduced.

[0099] Further, according to the present embodiment, in the storage unit 6, a plurality of individual storage areas ARR in which the inspection results of the plurality of discharge units D are stored are arranged in a specific order. For this reason, according to the present embodiment, compared with the mode in which a plurality of individual storage areas ARR in which the inspection results of the plurality of discharge units D are stored in the storage unit 6 are arranged in a random order, the time for accessing the individual storage area ARR in which the inspection result of the desired discharge unit D among the plurality of discharge units D is stored can be shortened. Thereby, according to the present embodiment, it is possible to realize high-speed reading when reading the inspection result of the desired discharge unit D among the plurality of discharge units D.

[0100] Further, in the inkjet printer 1 according to the present embodiment, the inspection unit 5 inspects the ink discharge state in the discharge unit D based on a detection signal SK indicating the detection result of the vibration remaining in the discharge unit D after the discharge unit D is driven.

[0101] Further, in the inkjet printer 1 according to the present embodiment, after inspecting one discharge unit D among the plurality of discharge units D provided in the head unit 3, the inspection unit 5 may be able to inspect any discharge unit D among the plurality of discharge units D provided in the head unit 3.

[0102] According to the present embodiment, even when the ejection state inspection process is executed in a random order for a plurality of ejection units D among the M ejection units D[1] to D[M] provided in the head unit 3, the inspection results corresponding to the plurality of ejection units D that are the targets of the ejection state inspection process are stored in a plurality of individual storage areas ARR that correspond one-to-one with the plurality of ejection units D. Therefore, for example, compared with a mode in which the individual storage areas ARR for the inspection results corresponding to the plurality of ejection units D are determined based on the inspection order, the time required to access the individual storage area ARR in which the inspection result of a desired ejection unit D among the plurality of ejection units D is stored can be shortened.

[0103] Further, in the inkjet printer 1 according to the present embodiment, the storage unit 6 may be a FIFO memory.

[0104] According to the present embodiment, since a widely used FIFO memory is adopted, for example, the manufacturing cost of the inkjet printer 1 can be suppressed lower than in the case of adopting a memory that is not a popular product. Further, according to the present embodiment, even when there are restrictions on the input / output order, such as in the case of a FIFO memory, the inspection results of the plurality of ejection units D can be stored in and read from the plurality of individual storage areas ARR in accordance with the restrictions on the input / output order.

[0105] Further, in the inkjet printer 1 according to the present embodiment, the inspection unit 5 includes an inspection result storage circuit 53 that temporarily stores ejection unit identification information DD, which is information for identifying the ejection unit D that is the target of the ejection state inspection process among the plurality of ejection units D provided in the head unit 3, and an inspection result signal DK, which is information indicating the result of the inspection of the ejection unit D.

[0106] According to the present embodiment, since the inspection unit 5 includes the inspection result storage circuit 53, even when the ejection state inspection process is executed in a random order for the M ejection units D included in the head unit 3, for the plurality of individual storage areas ARR included in the storage unit 6, it is possible to write the storage inspection result information DXX indicating the inspection result of the ejection unit D in a sequential order such as the order of the plurality of individual storage areas ARR. Therefore, according to the present embodiment, compared with the aspect in which the inspection unit 5 does not include the inspection result storage circuit 53, the writing of the storage inspection result information DXX to the storage unit 6 can be speeded up.

[0107] Further, in the inkjet printer 1 according to the present embodiment, the inspection result signal DK, which is information indicating the inspection result of the ejection unit D[mx] by the inspection unit 5, is stored in the individual storage area ARR[rx][s], and the ejection unit identification information DD, which is information for specifying the ejection unit D[mx] from among the plurality of ejection units D included in the head unit 3, is not stored.

[0108] According to the present embodiment, compared with the aspect of storing the ejection unit identification information DD for specifying the ejection unit D to be inspected by the inspection unit 5 in the storage unit 6, the memory amount for storing the inspection result of the ejection unit D in the storage unit 6 can be reduced.

[0109] <<B. Modification Example>> Each of the above embodiments can be variously modified. Specific modification modes are exemplified below. Two or more modes arbitrarily selected from the following examples can be appropriately combined within a range where they do not conflict with each other. In the modification examples exemplified below, for elements whose actions and functions are equivalent to those of the embodiments, the reference numerals referred to in the above description are reused, and the detailed description of each is appropriately omitted.

[0110] <<Modification Example 1>> In the above-described embodiment, the case where the inspection result storage area AR is composed of a plurality of individual storage areas ARR arranged two-dimensionally in R rows and S columns has been exemplified and described. However, the present invention is not limited to such a mode. The inspection result storage area AR may be composed of a plurality of individual storage areas ARR arranged one-dimensionally.

[0111] FIG. 11 is a block diagram showing an example of the configuration of the inspection result storage area AR according to this modification.

[0112] As shown in FIG. 11, in this modification, the inspection result storage area AR is composed of R individual storage areas ARR[1] to ARR[R] arranged one-dimensionally. Hereinafter, among the R individual storage areas ARR[1] to ARR[R], the r-th individual storage area ARR will be referred to as the individual storage area ARR[r]. In this modification, the value R is a natural number satisfying "3 ≤ R < M". Also, in this modification, for example, a shift register may be adopted as the storage unit 6.

[0113] In this modification, the inspection management unit 22 stores the storage inspection result information DXX[r] in the individual storage area ARR[r]. Therefore, also in this modification, similar to the above-described embodiment, it is possible to specify that the storage inspection result information DXX stored in the individual storage area ARR[r] from the location of the individual storage area ARR[r] in the inspection result storage area AR is information indicating the inspection result of the discharge unit D[r] in the discharge state inspection process.

[0114] <<Modification 2>> In the above-described embodiment and Modification 1, the mode in which the inspection unit 5 includes the inspection result storage circuit 53 has been exemplified and described. However, the present invention is not limited to such a mode. The inspection unit 5 may be configured without including the inspection result storage circuit 53. In this case, the inspection result output circuit 52 included in the inspection unit 5 may supply the inspection result individual information DKK[m] to the inspection management unit 22. And in this case, the inspection management unit 22 may generate the storage inspection result information DXX[m] based on the inspection result individual information DKK[m].

[0115] <<Modification Example 3>> In the above-described embodiments and Modification Examples 1 and 2, the case where the inspection unit 5 is provided separately from the head unit 3 has been illustrated and described. However, the present invention is not limited to such a mode. The inspection unit 5 may be provided in the head unit 3. In this case, as compared with the mode in which the inspection unit 5 is provided outside the head unit 3, it is possible to suppress the possibility of noise being mixed into the detection signal SK[m] supplied from the detection circuit 33 to the inspection unit 5, and thereby, the accuracy of the inspection in the inspection unit 5 can be improved.

[0116] <<Modification Example 4>> In the above-described embodiments and Modification Examples 1 to 3, the case where the inkjet printer 1 includes four head units 3 has been assumed. However, the present invention is not limited to such a mode. The inkjet printer 1 may include one or more and three or less head units 3, or may include five or more head units 3.

[0117] <<Modification Example 5>> In the above-described embodiments and Modification Examples 1 to 4, the case where the inkjet printer 1 is a serial printer has been illustrated. However, the present invention is not limited to such a mode. The inkjet printer 1 may be a so-called line printer in which a plurality of nozzles N are provided in the head unit 3 so as to extend wider than the width of the recording paper PP.

Explanation of Reference Numerals

[0118] 1... Inkjet printer, 2... Control unit, 3... Head unit, 4... Drive signal generation unit, 5... Inspection unit, 6... Storage unit, 7... Conveyance unit, 21... Drive control unit, 22... Inspection management unit, 31... Supply circuit, 32... Recording head, 33... Detection circuit, 51... Waveform inspection circuit, 52... Inspection result output circuit, 53... Inspection result storage circuit, D... Discharge unit.

Claims

1. A liquid ejection head in which a plurality of ejection units including a first ejection unit that ejects liquid, a second ejection unit that ejects liquid, and a third ejection unit that ejects liquid are arranged side by side, An inspection unit that inspects the liquid ejection state of each of the plurality of ejection units, A storage unit in which a plurality of memory areas including a first memory area, a second memory area, and a third memory area are arranged in a specific order and that stores the inspection results by the inspection unit, comprising: Regardless of the order of inspection of the plurality of ejection units by the inspection unit, The inspection result of the first ejection unit by the inspection unit is stored in the first memory area, The inspection result of the second ejection unit by the inspection unit is stored in the second memory area, The inspection result of the third ejection unit by the inspection unit is stored in the third memory area, A liquid ejection device characterized by the above.

2. The inspection unit inspects the liquid ejection state in the ejection unit based on the detection result of vibration remaining in the ejection unit after the ejection unit is driven. The liquid ejection device according to claim 1, characterized by the above.

3. The inspection unit After inspecting one of the plurality of ejection units, it is possible to inspect any of the plurality of ejection units. The liquid ejection device according to claim 1, characterized by the above.

4. The storage unit is a FIFO memory. The liquid ejection device according to claim 1, characterized by the above.

5. The inspection unit includes a temporary storage unit that temporarily stores information for identifying the ejection unit that is the object of inspection among the plurality of ejection units and the result of the inspection. The liquid ejection device according to claim 1, characterized in that...

6. In the first memory area, information indicating the inspection result of the first ejection unit by the inspection unit is stored, information for identifying the first ejection unit from among the plurality of ejection units is not stored, The liquid ejection device according to claim 1, characterized in that...

7. An inspection method for a liquid ejection head in which a plurality of ejection units including a first ejection unit for ejecting liquid, a second ejection unit for ejecting liquid, and a third ejection unit for ejecting liquid are arranged side by side, inspecting the ejection state of the liquid in each of the plurality of ejection units, with respect to a storage unit including a plurality of memory areas including a first memory area, a second memory area, and a third memory area arranged in a specific order and storing the inspection results by the inspection unit, regardless of the order of inspection of the plurality of ejection units by the inspection unit, storing the inspection result of the first ejection unit by the inspection unit in the first memory area, storing the inspection result of the second ejection unit by the inspection unit in the second memory area, storing the inspection result of the third ejection unit by the inspection unit in the third memory area, An inspection method for a liquid ejection head, characterized in that...

8. Inspecting the ejection state of the liquid in the ejection unit based on the detection result of the vibration remaining in the ejection unit after the ejection unit is driven, The inspection method for a liquid ejection head according to claim 7, characterized in that...

9. After inspecting one of the plurality of ejection units, it is possible to inspect any of the plurality of ejection units, The inspection method for a liquid ejection head according to claim 7, characterized in that...

10. The storage unit is a FIFO memory, The inspection method of the liquid ejection head according to claim 7, characterized in that...

11. With respect to the storage unit, Before storing the inspection result of the ejection unit that is the inspection target among the plurality of ejection units, With respect to a temporary storage unit that temporarily stores information for specifying the ejection unit that is the inspection target and the result of the inspection, Store the inspection result of the ejection unit that is the inspection target and the information for specifying the ejection unit that is the inspection target. The inspection method of the liquid ejection head according to claim 7, characterized in that...

12. In the first memory area, Information indicating the inspection result of the first ejection unit by the inspection unit is stored, Information for specifying the first ejection unit from among the plurality of ejection units is not stored. The inspection method of the liquid ejection head according to claim 7, characterized in that...

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