Liquid ejection head, liquid ejection apparatus, and method for controlling liquid ejection head

Abstract

The invention relates to a liquid ejection head, a liquid ejection apparatus, and a control method of the liquid ejection head. A liquid ejection head includes: an ejection section that ejects a liquid in response to supply of a drive signal; a supply unit that supplies a drive signal to the discharge unit; and a detection unit that detects vibrations in the ejection unit, the supply unit supplies an inspection drive signal having an inspection waveform among the drive signals to the ejection unit in a first unit period started by a first latch pulse among a plurality of latch pulses included in the latch signals supplied to the supply unit, and the detection unit detects vibrations in the ejection unit. The detection unit detects vibration remaining in the ejection unit in a second unit period that starts by the second latch pulse and ends by a second latch pulse provided next to the first latch pulse among the plurality of latch pulses, and the detection unit detects vibration remaining in the ejection unit in a second unit period that starts by the second latch pulse. And ends by a third latch pulse, which is arranged next to the second latch pulse, among the plurality of latch pulses.

Description

Technical Field

[0001] The present invention relates to a liquid ejection head, a liquid ejection device and a control method of the liquid ejection head. Background Art

[0002] Liquid ejection devices such as inkjet printers form images on a medium by driving an ejection unit of a liquid ejection head in each of a plurality of unit periods specified by a latch signal, and ejecting a liquid such as ink filled in the ejection unit in each of a plurality of unit periods. However, in a liquid ejection device, sometimes an abnormal ejection occurs in which the liquid cannot be ejected normally from the ejection unit. Therefore, a technology for checking the ejection state in the ejection unit has been proposed. For example, Patent Document 1 discloses a technology for checking the ejection state in the ejection unit based on a detection signal indicating vibration remaining in the ejection unit after the ejection unit is driven by a drive signal.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2020-044771

[0004] However, according to the conventional technology, when checking the ejection state in the ejection portion, since both driving the ejection portion by a driving signal and detecting the vibration remaining in the driven ejection portion are performed within the cycle of driving the ejection portion, i.e., the unit period, it is necessary to set the unit period to a sufficiently long time length. Summary of the invention

[0005] In order to solve the above technical problems, the liquid ejection head involved in the present invention is characterized in that it comprises: an ejection part, which ejects liquid according to the supply of a driving signal; a supply part, which supplies the driving signal to the ejection part; and a detection part, which detects the vibration in the ejection part, wherein the supply part supplies the inspection driving signal having an inspection waveform in the driving signal to the ejection part within a first unit period, the first unit period is started by a first latch pulse among a plurality of latch pulses included in a latch signal supplied to the supply part, and ends by a second latch pulse among the plurality of latch pulses which is set next to the first latch pulse, the detection part detects the vibration remaining in the ejection part within a second unit period, the second unit period is started by the second latch pulse, and ends by a third latch pulse among the plurality of latch pulses which is set next to the second latch pulse.

[0006] In addition, the liquid ejection device according to the present invention is characterized in that it comprises: an ejection part that ejects liquid according to the supply of a driving signal; a supply part that supplies the driving signal to the ejection part; and a detection part that detects vibration in the ejection part, wherein the supply part supplies a check driving signal having a check waveform in the driving signal to the ejection part within a first unit period, the first unit period is started by a first latch pulse among a plurality of latch pulses included in a latch signal supplied to the supply part, and ends by a second latch pulse among the plurality of latch pulses that is set next to the first latch pulse, and the detection part detects vibration remaining in the ejection part within a second unit period, the second unit period is started by the second latch pulse, and ends by a third latch pulse among the plurality of latch pulses that is set next to the second latch pulse.

[0007] In addition, the control method of a liquid ejection head involved in the present invention is a control method of a liquid ejection head, characterized in that the liquid ejection head comprises: an ejection part that ejects liquid according to the supply of a driving signal; a supply part that supplies the driving signal to the ejection part; and a detection part that detects vibration in the ejection part. In the control method, the liquid ejection head is controlled so that the supply part supplies the ejection part with a check driving signal having a check waveform in the driving signal within a first unit period, the first unit period is started by a first latch pulse among a plurality of latch pulses included in a latch signal supplied to the supply part, and ends by a second latch pulse among the plurality of latch pulses that is set next to the first latch pulse; and the liquid ejection head is controlled so that the detection part detects vibration remaining in the ejection part within a second unit period, the second unit period is started by the second latch pulse, and ends by a third latch pulse among the plurality of latch pulses that is set next to the second latch pulse. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 It is a block diagram showing an example of the configuration of the inkjet printer 1 according to the embodiment of the present invention.

[0009] Figure 2 This is a perspective view showing an example of a schematic internal structure of the inkjet printer 1 .

[0010] Figure 3 It is a cross-sectional view for explaining an example of the structure of the ejection portion D[m].

[0011] Figure 4 It is a block diagram showing an example of the configuration of the head unit 3 .

[0012] Figure 5It is a timing chart for explaining an example of a signal supplied to the head unit 3 .

[0013] Figure 6 2 is a block diagram showing an example of the configuration of the connection state specifying circuit 34.

[0014] Figure 7 This is an explanatory diagram for explaining an example of the operation of the decoder DC[m].

[0015] Figure 8 2 is a timing chart for explaining an example of supplying the driving signal Vin[m].

[0016] Fig. 9 SK[m] is a timing chart for explaining an example of the detection signal SK[m].

[0017] Fig.10 It is an explanatory diagram for explaining an example of the operation of the inspection unit 5 .

[0018] Fig.11 It is a timing chart for explaining an example of a signal supplied to the head unit 3 according to the reference example.

[0019] Fig.12 This is an explanatory diagram for explaining an example of the operation of the decoder DC[m] involved in the reference example.

[0020] Fig.13 It is a timing chart for explaining an example of the supply drive signal Vin-W[m] involved in the reference example.

[0021] Fig.14 It is a block diagram showing an example of the configuration of a head unit 3Z according to Modification 1 of the present invention.

[0022] Fig.15 This is a timing chart for explaining an example of a signal supplied to the head unit 3Z according to the first modification.

[0023] Fig.16 1 is a block diagram showing an example of the configuration of the connection state designation circuit 34Z according to the first modification.

[0024] Fig.17 This is an explanatory diagram for explaining an example of the operation of the decoder DCz[m] involved in the first modification.

[0025] Fig.18 It is a timing chart for explaining an example of the supply drive signal Vin-Z[m] according to the first modification.

[0026] Description of Reference Numerals

[0027] 1: inkjet printer; 2: control unit; 3: head unit; 4: drive signal generating unit; 5: inspection unit; 6: storage unit; 7: conveying unit; 31: supply circuit; 32: recording head; 33: detection circuit. DETAILED DESCRIPTION

[0028] The following is a description of the method for implementing the present invention with reference to the accompanying drawings. However, in each figure, the size and scale of each part are appropriately different from the actual one. In addition, the embodiments described below are suitable specific examples of the present invention, so various technically preferred limitations are added. However, as long as there is no special description in the following description to limit the meaning of the present invention, the scope of the present invention is not limited to these methods.

[0029] A. Implementation Method

[0030] In the present embodiment, the liquid ejecting device is described by taking an inkjet printer that ejects ink to form an image on recording paper PP as an example.

[0031] 1. Overview of inkjet printers

[0032] Refer to the following Figures 1 to 3 , an example of the structure of the inkjet printer 1 involved in this embodiment is described.

[0033] Figure 1 1 is a functional block diagram showing an example of the configuration of the inkjet printer 1 .

[0034] like Figure 1 As shown, print data Img indicating an image to be formed by the inkjet printer 1 is supplied from a host computer such as a personal computer or a digital camera to the inkjet printer 1. The inkjet printer 1 executes a print process to form an image indicated by the print data Img supplied from the host computer on recording paper PP.

[0035] like Figure 1 As shown, the inkjet printer 1 includes a control unit 2 for controlling each unit of the inkjet printer 1, a head unit 3 provided with a discharge unit D for discharging ink, a drive signal generating unit 4 for generating a drive signal Com for driving the discharge unit D, a checking unit 5 for checking the discharge state of the ink in the discharge unit D, a storage unit 6 for storing various information, and a conveying unit 7 for changing the relative position of the recording paper PP and the head unit 3. It should be noted that the inkjet printer 1 is an example of a "liquid discharge device", ink is an example of a "liquid", and the head unit 3 is an example of a "liquid discharge head".

[0036] In this embodiment, it is assumed that the inkjet printer 1 has one or more head units 3, one or more drive signal generating units 4 corresponding to the one or more head units 3, and one or more inspection units 5 corresponding to the one or more head units 3. Specifically, in this embodiment, the inkjet printer 1 has four head units 3, four drive signal generating units 4 corresponding to the four head units 3, and four inspection units 5 corresponding to the four head units 3. However, in the following, for the sake of convenience, as Figure 1 As shown, the description will focus on one head unit 3 among the four head units 3, one of the four drive signal generating units 4 provided corresponding to the one head unit 3, and one of the four inspection units 5 provided corresponding to the one head unit 3.

[0037] The control unit 2 is configured to include one or more CPUs (Central Processing Units). However, the control unit 2 may also be a unit having a programmable logic device such as an FPGA (field-programmable gate array) instead of a CPU, or the control unit 2 may be a unit having a programmable logic device such as an FPGA in addition to a CPU. In addition, the control unit 2 includes a memory. The memory is configured to include a volatile memory such as a RAM (Random Access Memory) and one or both of a non-volatile memory such as a ROM (Read Only Memory), an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a PROM (Programmable ROM).

[0038] As will be described in detail later, the control unit 2 generates signals such as the designation signal SI and the waveform designation signal dCom for controlling the operation of each unit of the inkjet printer 1 .

[0039] Here, the waveform designation signal dCom is a digital signal that specifies the waveform of the drive signal Com.

[0040] In addition, the drive signal Com is an analog signal for driving the ejection portion D. In the present embodiment, it is assumed that the drive signal Com includes a drive signal Com-A, a drive signal Com-B, and a drive signal Com-C. It should be noted that, in the present embodiment, the drive signal Com-B is an example of a "check drive signal", and the drive signal Com-C is an example of a "detection drive signal".

[0041] The designation signal SI is a digital signal that designates the type of operation of the discharge unit D. Specifically, the designation signal SI designates whether the drive signal Com is supplied to the discharge unit D, thereby designating the type of operation of the discharge unit D, such as whether the discharge unit D discharges ink.

[0042] When executing the printing process, the control unit 2 generates a signal such as a designation signal SI for controlling the head unit 3 based on the printing data Img. In addition, the control unit 2 generates a signal such as a waveform designation signal dCom for controlling the drive signal generating unit 4 when executing the printing process. In addition, the control unit 2 generates a signal for controlling the conveying unit 7 when executing the printing process. Thus, during the printing process, the control unit 2 controls the conveying unit 7 to change the relative position between the recording paper PP and the head unit 3, adjusts the presence or absence of ink ejection from the ejection unit D and the timing of ink ejection, and controls each part of the inkjet printer 1 to form an image corresponding to the printing data Img on the recording paper PP.

[0043] like Figure 1 As shown, the head unit 3 includes a supply circuit 31, a recording head 32, and a detection circuit 33. The supply circuit 31 is an example of a "supply unit", and the detection circuit 33 is an example of a "detection unit".

[0044] The recording head 32 has M ejection units D. Here, the value M is a natural number satisfying "M ≥ 1". It should be noted that, hereinafter, the m-th ejection unit D among the M ejection units D provided in the recording head 32 is sometimes referred to as an ejection unit D[m]. Here, the variable m is a natural number satisfying "1 ≤ m ≤ M". In addition, hereinafter, when a component or signal of the inkjet printer 1 corresponds to an ejection unit D[m] among the M ejection units D, a footnote [m] may be added to the reference numeral used to indicate the component or signal.

[0045] The supply circuit 31 switches whether to supply the drive signal Com to the ejection unit D[m] based on the designation signal SI. Hereinafter, the drive signal Com supplied to the ejection unit D[m] among the drive signals Com may be referred to as a supply drive signal Vin[m].

[0046] In addition, the supply circuit 31 switches whether to supply the detection potential signal VX[m] to the detection circuit 33 based on the designated signal SI. Here, the detection potential signal VX[m] is a signal indicating the potential of the upper electrode Zu[m] of the piezoelectric element PZ[m] provided in the ejection part D[m]. In the following, when the detection potential signal VX[m] is supplied from the ejection part D[m] to the detection circuit 33, the ejection part D[m] is sometimes referred to as the inspection object ejection part DS. It should be noted that regarding the piezoelectric element PZ[m] and the upper electrode Zu[m], Figure 3To be described later.

[0047] The detection circuit 33 generates the detection signal SK[m] based on the detection potential signal VX[m] supplied from the discharge portion D[m] set as the inspection target discharge portion DS through the supply circuit 31. Specifically, the detection circuit 33 generates the detection signal SK[m] by amplifying the detection potential signal VX[m] and removing noise components, for example.

[0048] The inspection unit 5 checks whether the ink ejection state in the inspection object ejection unit DS is normal based on the detection signal SK[m]. In other words, the inspection unit 5 checks whether there is no ejection abnormality in the inspection object ejection unit DS based on the detection signal SK[m]. Then, the inspection unit 5 generates the inspection result information SH[m] showing the result of the inspection. Here, the inspection result information SH[m] refers to information showing whether an ejection abnormality has occurred in the ejection unit D[m] selected as the inspection object ejection unit DS. In addition, the ejection abnormality is a general term for the state in which the nozzle N provided by the ejection unit D[m] cannot eject the ink normally. For example, the ejection abnormality includes a state in which the 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 ejection amount of the ink specified by the drive signal Com, and a state in which the ejection unit D[m] ejects the ink at a speed different from the ejection speed of the ink specified by the drive signal Com.

[0049] Hereinafter, the process of checking the ink ejection state of the ejection unit D[m] by driving the ejection unit D[m] as the inspection target ejection unit DS is referred to as the ejection state inspection process. In addition, in the ejection state inspection process, the process of driving the ejection unit D[m] as the inspection target ejection unit DS is referred to as the inspection target drive process. In addition, in the ejection state inspection process, the inspection target ejection unit DS that is the object of the ejection state inspection process and the ejection unit D[m] that is the object of the inspection target drive process is referred to as the inspection drive ejection unit DS1.

[0050] In addition, hereinafter, the process of detecting the detection potential signal VX[m] from the ejection unit D[m] driven as the ejection unit DS to be inspected in the ejection state inspection process is referred to as the residual vibration detection process. In addition, hereinafter, the ejection unit D[m] which is the ejection unit DS to be inspected and the ejection unit D[m] to be inspected as the ejection unit DS to be inspected and the ejection unit D[m] to be inspected as the ejection unit DS to be inspected is referred to as the vibration detection ejection unit DS2.

[0051] When the inspection object drive process is executed, the control unit 2 generates a signal such as a designation signal SI for controlling the head unit 3. In addition, when the inspection object drive process is executed, the control unit 2 generates a signal such as a waveform designation signal dCom for controlling the drive signal generation unit 4. Thus, the control unit 2 drives the discharge unit D[m] as the inspection drive discharge unit DS1 in the inspection object drive process.

[0052] When performing the residual vibration detection process, the control unit 2 controls the head unit 3 by generating a designated signal SI so that the detection circuit 33 is supplied with a detection potential signal VX[m] corresponding to the ejection unit D[m] driven as the inspection drive ejection unit DS1 in the inspection object drive process. In addition, when performing the residual vibration detection process, the control unit 2 drives the ejection unit D[m] driven as the inspection drive ejection unit DS1 in the inspection object drive process as the vibration detection ejection unit DS2 by generating a designated signal SI. Then, when performing the residual vibration detection process, 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 vibration detection ejection unit DS2.

[0053] Figure 2 This is a perspective view showing an example of a schematic internal structure of the inkjet printer 1 .

[0054] like Figure 2 As shown, in this embodiment, it is assumed that the inkjet printer 1 is a serial printer. Specifically, when the inkjet printer 1 performs printing processing, the inkjet printer 1 ejects ink from the ejection portion D[m] while conveying the recording paper PP in the X1 direction and moving the head unit 3 back and forth in the Y1 direction intersecting the X1 direction and the Y2 direction which is the opposite direction of the Y1 direction, thereby forming dots Dt corresponding to the print data Img on the recording paper PP.

[0055] Hereinafter, the X1 direction and the X2 direction as its opposite direction are collectively referred to as the "X-axis direction", the Y1 direction intersecting the X-axis direction and the Y2 direction as its opposite direction are collectively referred to as the "Y-axis direction", and the Z1 direction intersecting the X-axis direction and the Y-axis direction and the Z2 direction as its opposite direction are collectively referred to as the "Z-axis direction". In the present embodiment, as an example, it is assumed that the X-axis direction, the Y-axis direction and the Z-axis direction are orthogonal to each other for illustration. However, the present invention is not limited to such a form. The X-axis direction, the Y-axis direction and the Z-axis direction only need to intersect each other. It should be noted that in the present embodiment, the Z1 direction is set as the direction in which ink is ejected from the ejection portion D[m].

[0056] like Figure 2As shown, 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 in the housing 100 and that carries four head units 3 .

[0057] In this embodiment, if Figure 2 As shown, it is assumed that the carriage 110 stores four ink cartridges 120 corresponding to the four colors of ink, cyan, magenta, yellow, and black. In addition, in the present embodiment, as described above, it is assumed that the inkjet printer 1 has four head units 3 corresponding to the four ink cartridges 120. Each ejection portion D[m] receives the supply of ink from the ink cartridge 120 corresponding to the head unit 3 provided with the ejection portion D[m]. Thus, each ejection portion D[m] can fill the supplied ink inside and eject the ink filled inside the ejection portion D[m] from the nozzle N provided in the ejection portion D[m]. It should be noted that the ink cartridge 120 may also be provided outside the carriage 110.

[0058] In addition, as described above, the inkjet printer 1 according to this embodiment includes the transport unit 7. Figure 2 As shown, the conveying unit 7 includes a carriage conveying mechanism 71 for reciprocating the carriage 110 in the Y-axis direction, a carriage guide shaft 76 for supporting the carriage 110 so as to freely reciprocate in the Y-axis direction, a medium conveying mechanism 73 for conveying the recording paper PP, and a platen 75 provided in the Z1 direction of the carriage 110. Therefore, when performing the printing process, the conveying unit 7 causes the head unit 3 to reciprocate along the carriage guide shaft 76 in the Y-axis direction together with the carriage 110 through the carriage conveying mechanism 71, and conveys the recording paper PP on the platen 75 in the X1 direction through the medium conveying mechanism 73, thereby changing the relative position of the recording paper PP and the head unit 3, and making it possible to drop ink on the entire recording paper PP.

[0059] Figure 3 It is a partial schematic cross-sectional view of the recording head 32 obtained by cutting the recording head 32 in a state including the discharge portion D[m].

[0060] like Figure 3As shown, the ejection unit D[m] includes a piezoelectric element PZ[m], a cavity CV filled with ink, a nozzle N connected to the cavity CV, and a vibration plate 321. The ejection unit D[m] is driven by the piezoelectric element PZ[m] by supplying a driving signal Vin[m], so that the ink in the cavity CV is ejected from the nozzle N. The cavity CV is a space defined by a cavity plate 324, a nozzle plate 323 formed with the nozzle N, and a vibration plate 321. The cavity CV is connected to a reservoir 325 through an ink supply port 326. The reservoir 325 is connected to the ink cartridge 120 corresponding to the ejection unit D[m] through an ink inlet 327. The piezoelectric element PZ[m] includes 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. In addition, when the upper electrode Zu[m] is supplied with a driving signal Vin[m] to apply a voltage 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 connected to the vibration plate 321. Therefore, when the piezoelectric element PZ[m] is driven to vibrate by the supply driving signal Vin[m], the vibration plate 321 also vibrates. Then, due to the vibration of the vibration plate 321, the volume of the cavity CV and the pressure in the cavity CV change, and the ink filled in the cavity CV is ejected from the nozzle N.

[0061] 2. Overview of the head unit

[0062] Refer to the following Figures 4 to 8 The outline of the head unit 3 will be described.

[0063] Figure 4 It is a block diagram showing an example of the configuration of the head unit 3 .

[0064] like Figure 4 As shown, the head unit 3 includes a supply circuit 31, a recording head 32, and a detection circuit 33. In addition, the head unit 3 includes wiring La, wiring Lb, wiring Lc, and wiring Ls, wherein the drive signal Com-A is supplied from the drive signal generating unit 4 to the wiring La, the drive signal Com-B is supplied from the drive signal generating unit 4 to the wiring Lb, and the drive signal Com-C is supplied from the drive signal generating unit 4 to the wiring Lc, and the wiring Ls is used to supply the detection circuit 33 with the detection potential signal VX[m].

[0065] The supply circuit 31 includes M switches Wa[1] to Wa[M] corresponding one-to-one to the M ejection parts D[1] to D[M], M switches Wb[1] to Wb[M] corresponding one-to-one to the M ejection parts D[1] to D[M], M switches Wc[1] to Wc[M] corresponding one-to-one to the M ejection parts D[1] to D[M], M switches Ws[1] to Ws[M] corresponding one-to-one to the M ejection parts D[1] to D[M], and a connection state designation circuit 34 that specifies the connection state of each switch.

[0066] The connection state designation circuit 34 generates a connection state designation signal Qa[m] for designating the on-off state of the switch Wa[m], a connection state designation signal Qb[m] for designating the on-off state of the switch Wb[m], a connection state designation signal Qc[m] for designating the on-off state of the switch Wc[m], and a connection state designation signal Qs[m] for designating the on-off state of the switch Ws[m] based on the designation signal SI, the latch signal LAT, and the period designation signal Tsig supplied from the control unit 2.

[0067] The switch Wa[m] switches the connection and non-conduction between the wiring La and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Qa[m]. In the present embodiment, the switch Wa[m] is turned on when the connection state designation signal Qa[m] is at a high level, and is turned off when the connection state designation signal Qa[m] is at a low level. When the switch Wa[m] is turned on, the drive signal Com-A supplied to the wiring La is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection portion D[m].

[0068] The switch Wb[m] switches the connection and non-conduction between the wiring Lb and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Qb[m]. In the present embodiment, the switch Wb[m] is turned on when the connection state designation signal Qb[m] is at a high level, and is turned off when the connection state designation signal Qb[m] is at a low level. When the switch Wb[m] is turned on, the drive signal Com-B supplied to the wiring Lb is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection portion D[m].

[0069] The switch Wc[m] switches between the conduction and non-conduction of the wiring Lc and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Qc[m]. In the present embodiment, the switch Wc[m] is turned on when the connection state designation signal Qc[m] is at a high level, and is turned off when the connection state designation signal Qc[m] is at a low level. When the switch Wc[m] is turned on, the drive signal Com-C supplied to the wiring Lc is supplied as the supply drive signal Vin[m] to the upper electrode Zu[m] of the ejection portion D[m].

[0070] The switch Ws[m] switches between the conduction and non-conduction of the wiring Ls and the upper electrode Zu[m] of the piezoelectric element PZ[m] based on the connection state designation signal Qs[m]. In the present embodiment, the switch Ws[m] is turned on when the connection state designation signal Qs[m] is at a high level, and is turned off when the connection state designation signal Qs[m] is at a low level. When the switch Ws[m] is turned on, the potential of the upper electrode Zu[m] provided at the ejection portion D[m] is supplied to the detection circuit 33 as the detection potential signal VX[m] through the wiring Ls.

[0071] 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].

[0072] When the inkjet printer 1 performs a printing process or a discharge state inspection process, a plurality of unit periods TP are set as the operation period of the inkjet printer 1. For the printing process or the discharge state inspection process, the inkjet printer 1 can drive each discharge unit D within each unit period TP. It should be noted that, hereinafter, the kth unit period TP among the plurality of unit periods TP set as the operation period of the inkjet printer 1 is referred to as a unit period TP(k). Here, the variable k is a natural number satisfying k≥1.

[0073] Figure 5 1 is a timing chart showing an example of various signals such as the drive signal Com supplied to the head unit 3 within a plurality of unit periods TP.

[0074] like Figure 5 As shown, the control unit 2 outputs a latch signal LAT having a plurality of pulses PLL. Thus, the control unit 2 defines the unit period TP as the period from the rising edge of the pulse PLL to the rising edge of the next pulse PLL. It should be noted that in this embodiment, the pulse PLL is an example of a "latch pulse".

[0075] Hereinafter, the pulse PLL that defines the start of the unit period TP(k) is referred to as the pulse PLL(k). That is, the control unit 2 defines the unit period TP(k) as the period from the rising edge of the pulse PLL(k) of the latch signal LAT to the rising edge of the pulse PLL(k+1) of the latch signal LAT, and defines the unit period TP(k+1) as the period from the rising edge of the pulse PLL(k+1) of the latch signal LAT to the rising edge of the pulse PLL(k+2) of the latch signal LAT.

[0076] The control unit 2 outputs a period designation signal Tsig having a pulse PLT1 and a pulse PLT2 within a 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.

[0077] Hereinafter, the pulse PLT1 provided in the unit period TP(k) is referred to as a pulse PLT1(k), and the pulse PLT2 provided in the unit period TP(k) is referred to as a pulse PLT2(k).

[0078] like Figure 5 As shown, the designation signal SI includes M individual designation signals Sd[1] to Sd[M] corresponding one-to-one to the M ejection units D[1] to D[M]. The individual designation signal Sd[m] designates the driving form of the ejection unit D[m] within each unit period TP when the inkjet printer 1 performs a printing process or an ejection state inspection process. Before each unit period TP, the control unit 2 synchronizes the designation signal SI including the M individual designation signals Sd[1] to Sd[M] with the clock signal CL and supplies it to the connection state designation circuit 34. Then, the connection state designation circuit 34 generates the connection state designation signal Qa[m], the connection state designation signal Qb[m], the connection state designation signal Qc[m], and the connection state designation signal Qs[m] based on the individual designation signal Sd[m] within the unit period TP.

[0079] In this embodiment, within the unit period TP for executing the printing process or the ejection status check process, the individual designated signal Sd[m] can take any one of four values: a value "1" for designating the ejection unit D[m] as the printing ejection unit DP, a value "2" for designating the ejection unit D[m] as the dot non-forming ejection unit DN, a value "3" for designating the ejection unit D[m] as the inspection drive ejection unit DS1, and a value "4" for designating the ejection unit D[m] as the vibration detection ejection unit DS2.

[0080] Here, the printing ejection unit DP is an ejection unit D that ejects ink from the nozzle N within the unit period TP and forms a dot Dt on the recording paper PP. In addition, the dot non-forming ejection unit DN is an ejection unit D that does not eject ink from the nozzle N within the unit period TP and does not form a dot Dt on the recording paper PP. In addition, as described above, the inspection drive ejection unit DS1 is an ejection unit D that becomes the object of the inspection object drive process within the unit period TP among the inspection object ejection units DS. In addition, as described above, the vibration detection ejection unit DS2 is an ejection unit D that becomes the object of the residual vibration detection process within the unit period TP among the inspection object ejection units DS.

[0081] like Figure 5 As shown, the drive signal Com-A has a waveform PA1 set in each unit period TP. Here, the waveform PA1 is a waveform that returns to the reference potential V0 from the reference potential V0 through the potential VL1 lower than the reference potential V0 and the potential VH1 higher than the reference potential V0 in each unit period TP. When the supply drive signal Vin[m] having the waveform PA1 is supplied to the ejection portion D[m], the waveform PA1 is determined so that the ink corresponding to the dot Dt is ejected from the ejection portion D[m].

[0082] It should be noted that in the present embodiment, as an example, it is assumed that when the potential of the supply drive signal Vin[m] supplied to the ejection portion D[m] is high, the volume of the cavity CV provided in the ejection portion D[m] becomes smaller than when the potential of the supply drive signal Vin[m] supplied to the ejection portion D[m] is low. Therefore, when the ejection portion D[m] is driven by the supply drive signal Vin[m] having the waveform PA1, the potential of the supply drive signal Vin[m] changes from low to high, so that the ink in the ejection portion D[m] is ejected from the nozzle N.

[0083] Hereinafter, the time length from the end of the waveform PA1 of the drive signal Com-A to the end of the unit period TP provided with the waveform PA1 is sometimes referred to as the time length GA1. Specifically, the time length GA1 is the time length from the timing when the potential of the waveform PA1 of the drive signal Com-A completes the change from the potential VH1 to the reference potential V0 to the timing when the unit period TP provided with the waveform PA1 ends.

[0084] like Figure 5 As shown, the drive signal Com-B has a waveform PB provided in each unit period TP. Here, the waveform PB is a waveform that returns from the reference potential V0 to the reference potential V0 via a potential VB higher than the reference potential V0 in each unit period TP.

[0085] It should be noted that, in the present embodiment, the reference potential V0 is an example of the “first potential”, and the potential VB is an example of the “second potential”.

[0086] Hereinafter, the time length from the end of the waveform PB of the drive signal Com-B to the end of the unit period TP provided with the waveform PB is sometimes referred to as the time length GB. Specifically, the time length GB is the time length from the timing when the potential of the waveform PB of the drive signal Com-B completes the change from the potential VB to the reference potential V0 to the timing when the unit period TP provided with the waveform PB ends.

[0087] In addition, hereinafter, the time length required for the waveform PB of the drive signal Com-B to change from the reference potential V0 to the potential VB is referred to as the time length GBu, and the time length required for the waveform PB of the drive signal Com-B to change from the potential VB to the reference potential V0 is referred to as the time length GBd. In the present embodiment, the time length GBu is adjusted so that ink is not ejected from the ejection portion D[m] even if the ejection portion D[m] is driven by the drive signal Com-B. Specifically, in the present embodiment, the waveform PB is set so that the time length GBu becomes longer than the time length GBd.

[0088] like Figure 5 As shown, the drive signal Com-C is a signal that maintains the reference potential V0 during the control period TS1 and the control period TS2 in each unit period TP and is provided with a waveform PC during the control period TS3 in each unit period TP. Here, the waveform PC is a waveform that returns from the reference potential V0 to the reference potential V0 via the potential VC having a potential lower than the reference potential V0. In the present embodiment, the waveform PC is provided so that ink is not ejected from the ejection portion D[m] even if the ejection portion D[m] is driven by the drive signal Com-C. In addition, in the present embodiment, the ink inside the cavity CV of the ejection portion D[m] is stirred by driving the ejection portion D[m] with the drive signal Com-C having the waveform PC, so that the viscosity increase of the ink inside the ejection portion D[m] can be suppressed.

[0089] In the following, the time length from the end of the waveform PC of the drive signal Com-C to the end of the unit period TP provided with the waveform PC is sometimes referred to as the time length GC. Specifically, the time length GC is the time length from the timing when the potential of the waveform PC of the drive signal Com-C completes the change from the potential VC to the reference potential V0 to the timing when the unit period TP provided with the waveform PC ends.

[0090] In addition, in the present embodiment, the waveform PA1, the waveform PB, and the waveform PC are provided in such a manner that the time length GB is shorter than the time length GA1, and the time length GB is shorter than the time length GC. That is, in the present embodiment, the time length GB from the end of the waveform PB to the end of the unit period TP in which the waveform PB is provided is shorter than the time length GA1 from the end of the waveform PA1 to the end of the unit period TP in which the waveform PA1 is provided, and is shorter than the time length GC from the end of the waveform PC to the end of the unit period TP in which the waveform PC is provided.

[0091] Hereinafter, the waveform PA1 , the waveform PB, and the waveform PC may be collectively referred to as a “driving waveform.” In addition, in the present embodiment, the waveform PB is an example of a “test waveform.”

[0092] It should be noted that, in this embodiment, the case where the drive signal Com-C has a waveform PC is described, but the present invention is not limited to such a form. For example, the drive signal Com-C may be a signal that maintains the reference potential V0 in each unit period TP.

[0093] Figure 6 2 is a block diagram showing an example of the configuration of the connection state specifying circuit 34.

[0094] like Figure 6 As shown, the connection state designation circuit 34 includes M transmission circuits SR[1] to SR[M] provided in one-to-one correspondence with the M ejection parts D[1] to D[M], M latch circuits LT[1] to LT[M] provided in one-to-one correspondence with the M ejection parts D[1] to D[M], and M decoders DC[1] to DC[M] provided in one-to-one correspondence with the M ejection parts D[1] to D[M]. The individual designation signals Sd[1] to Sd[M] are supplied serially to the transmission circuit SR[1]. Then, the individual designation signal Sd[m] supplied to the transmission circuit SR[1] is sequentially transmitted from the transmission circuit SR[1] to the transmission circuit SR[m] in synchronization with the clock signal CL through m transmission circuits SR[1] to SR[m] among the M transmission circuits SR[1] to SR[M]. In addition, the latch circuit LT[m] latches the individual designation signal Sd[m] supplied to the transmission circuit SR[m] at the timing when the pulse PLL of the latch signal LAT rises to a high level. In addition, the decoder DC[m] generates the connection state designation signal Qa[m], the connection state designation signal Qb[m], the connection state designation signal Qc[m], and the connection state designation signal Qs[m] based on the individual designation signal Sd[m], the latch signal LAT, and the period designation signal Tsig.

[0095] Figure 7 This is an explanatory diagram showing an example of the operation of the decoder DC[m].

[0096] like Figure 7 As shown in FIG. 1 , when the individual designation signal Sd[m] indicates the value "1" that the ejection unit D[m] is designated as the printing ejection unit DP in the unit period TP, the decoder DC[m] sets the connection state designation signal Qa[m] to a high level in the entire unit period TP. In this case, the switch Wa[m] is turned on in the entire unit period TP. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA1 in the unit period TP, and ejects ink in an amount corresponding to the dot Dt.

[0097] In addition, when the individual designation signal Sd[m] indicates a value "2" that designates the ejection unit D[m] as the dot non-forming ejection unit DN within the unit period TP, the decoder DC[m] sets the connection state designation signal Qa[m], the connection state designation signal Qb[m], the connection state designation signal Qc[m], and the connection state designation signal Qs[m] to a low level within the entire unit period TP. In this case, the switch Wa[m], the switch Wb[m], the switch Wc[m], and the switch Ws[m] are disconnected within the entire unit period TP. Therefore, the ejection unit D[m] is not driven by the driving signal Vin[m] within the unit period TP, and ink is not ejected.

[0098] In addition, when the individual designation signal Sd[m] indicates the value "3" that the ejection unit D[m] is designated as the test drive ejection unit DS1 within the unit period TP, the decoder DC[m] sets the connection state designation signal Qb[m] to a high level within the entire unit period TP. In this case, the switch Wb[m] is turned on within the entire unit period TP. Therefore, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PB within the unit period TP, and vibration occurs in the ejection unit D[m].

[0099] In addition, when the individual designation signal Sd[m] indicates the value "4" that the ejection unit D[m] is designated as the vibration detection ejection unit DS2 within the unit period TP, the decoder DC[m] sets the connection state designation signal Qc[m] to a high level within the control period TS1 and the control period TS3, and sets the connection state designation signal Qs[m] to a high level within the control period TS2. In this case, the switch Wc[m] is turned on within the control period TS1 and the control period TS3, and the switch Ws[m] is turned on within the control period TS2. Therefore, when vibration remains in the ejection unit D[m] within 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 ejection unit D[m] as the detection potential signal VX[m] through the switch Ws[m] within the control period TS2.

[0100] It should be noted that the waveform of the detection potential signal VX[m] detected from the ejection portion D[m] during the control period TS2 shows the waveform of the vibration remaining in the ejection portion D[m] during the control period TS2. In addition, the waveform of the detection signal SK[m] generated based on the detection potential signal VX[m] detected from the ejection portion D[m] during the control period TS2 shows the waveform of the vibration remaining in the ejection portion D[m] during the control period TS2.

[0101] Figure 8 1 is a timing chart showing an example of a plurality of supply drive signals Vin[m] to Vin[m+2] supplied to a plurality of discharge portions D[m] to D[m+2] provided in the head unit 3 within a plurality of unit periods TP(k) to TP(k+3).

[0102] It should be noted that in Figure 8 In the above, it is assumed that the variable m is a natural number satisfying "1≤m≤M-2". In addition, hereinafter, the supply drive signal Vin[m] supplied to the ejection unit D[m] in the unit period TP(k) is referred to as the supply drive signal Vin[m](k). In addition, in the following, the individual designation signal Sd[m] that designates the operation of the ejection unit D[m] in the unit period TP(k) is referred to as the individual designation signal Sd[m](k).

[0103] In addition, Figure 8 In the above, it is assumed that the inkjet printer 1 performs three ejection status inspection processes on the three ejection units D, namely, the ejection unit D[m], the ejection unit D[m+1], and the ejection unit D[m+2], within four unit periods TP, namely, the unit period TP(k), the unit period TP(k+1), the unit period TP(k+2), and the unit period TP(k+3). Figure 8 In the above, it is assumed that the inkjet printer 1 drives the ejection unit D which is not the target of the ejection state inspection process among the three ejection units D, namely the ejection unit D[m], the ejection unit D[m+1] and the ejection unit D[m+2], as the printing ejection unit D.

[0104] In this embodiment, when the inkjet printer 1 performs the ejection status inspection processing with the ejection part D[m] as the object, first, the inspection object drive processing with the ejection part D[m] as the object is performed within a unit period TP, and then, the residual vibration detection processing with the ejection part D[m] as the object is performed within other unit periods TP following this unit period TP.

[0105] Specifically, the control unit 2 generates the individual designation signal Sd[m](k) for designating the ejection unit D[m] as the inspection drive ejection unit DS1 within the unit period TP(k), and generates the individual designation signal Sd[m](k+1) for designating the ejection unit D[m] as the vibration detection ejection unit DS2 within the unit period TP(k+1). Figure 8 As shown, the inkjet printer 1 supplies the drive signal Com-B having the waveform PB as the supply drive signal Vin[m](k) to the ejection portion D[m] within the unit period TP(k), and supplies the drive signal Com-C having the waveform PC as the supply drive signal Vin[m](k+1) to the ejection portion D[m] within the unit period TP(k+1). As a result, the inkjet printer 1 performs the inspection target drive processing with the ejection portion D[m] as the target within the unit period TP(k), and then performs the residual vibration detection processing with the ejection portion D[m] as the target within the unit period TP(k+1).

[0106] In this case, the ejection unit D[m] is driven by the drive signal Com-B having the waveform PB to vibrate in the unit period TP(k) which is started by the pulse PLL(k) and ended by the pulse PLL(k+1). Then, the detection circuit 33 detects the vibration generated in the ejection unit D[m] in the unit period TP(k) due to the drive of the drive signal Com-B and remaining in the ejection unit D[m] in the unit period TP(k+1) in the control period TS2 in the unit period TP(k+1), and generates the detection signal SK[m] based on the detection potential signal VX[m] indicating the detection result. In this way, the inkjet printer 1 performs the ejection state inspection process for the ejection unit D[m].

[0107] It should be noted that in Figure 8 In the above, the inkjet printer 1 supplies the drive signal Com-B having the waveform PB as the supply drive signal Vin[m+1](k+1) to the ejection unit D[m+1], and supplies the drive signal Com-C having the waveform PC as the supply drive signal Vin[m+1](k+2) to the ejection unit D[m+1]. Thus, the inkjet printer 1 performs the inspection object drive processing with the ejection unit D[m+1] as the object within the unit period TP(k+1), and then performs the residual vibration detection processing with the ejection unit D[m+1] as the object within the unit period TP(k+2), thereby performing the ejection state inspection processing for the ejection unit D[m+1].

[0108] In addition, the inkjet printer 1 supplies the drive signal Com-B having the waveform PB as the supply drive signal Vin[m+2](k+2) to the ejection unit D[m+2], and supplies the drive signal Com-C having the waveform PC as the supply drive signal Vin[m+2](k+3) to the ejection unit D[m+2]. Thus, the inkjet printer 1 performs the inspection target drive processing with the ejection unit D[m+2] as the target within the unit period TP(k+2), and then performs the residual vibration detection processing with the ejection unit D[m+2] as the target within the unit period TP(k+3), thereby performing the ejection state inspection processing for the ejection unit D[m+2].

[0109] It should be noted that, in the present embodiment, the unit period TP(k) is an example of the “first unit period”, and the unit period TP(k+1) is an example of the “second unit period”. In addition, in the present embodiment, the pulse PLL(k) is an example of the “first latch pulse”, the pulse PLL(k+1) is an example of the “second latch pulse”, and the pulse PLL(k+2) is an example of the “third latch pulse”. In addition, in the present embodiment, the pulse PLT1(k+1) is an example of the “detection start pulse”, the pulse PLT2(k+1) is an example of the “detection end pulse”, and the control period TS2 included in the unit period TP(k+1) is an example of the “detection period”.

[0110] 3. Inspection unit

[0111] Refer to the following Fig. 9 and Fig.10 The outline of the inspection unit 5 will be described.

[0112] As described above, the inspection unit 5 inspects the ejection state of ink in the ejection portion D[m] designated as the inspection target ejection portion DS based on the detection signal SK[m] supplied from the detection circuit 33 .

[0113] Fig. 9 1 is a timing chart for explaining an example of the detection signal SK[m] supplied by the detection circuit 33 to the inspection unit 5. It should be noted that the detection signal SK[m] output by the detection circuit 33 during the control period TS2 shows a waveform based on the vibration remaining in the ejection portion D[m] during the control period TS2.

[0114] like Fig. 9 As shown, hereinafter, the period from the timing when the potential of the detection signal SK[m] matches the central potential VK0 set near the amplitude center of the detection signal SK[m] to the next timing when the potential matches the central potential VK0 is referred to as the cycle period NTC[m]. In addition, hereinafter, the time length of the cycle period NTC[m] is referred to as the cycle TC[m].

[0115] In this embodiment, the inspection unit 5 measures the period TC[m] of the detection signal SK[m]. Then, the inspection unit 5 inspects the ink ejection state in the ejection portion D[m] based on the period TC[m] and generates inspection result information SH[m] indicating the inspection result.

[0116] Fig.10 This is an explanatory diagram for explaining an example of generating the inspection result information SH[m] in the inspection unit 5.

[0117] like Fig.10 As shown, the inspection unit 5 inspects the ejection state of the ink in the ejection portion D[m] by comparing the period TC[m] with part or all of the threshold values ​​Tth1, Tth2, and Tth3, and generates inspection result information SH[m] showing the result of the inspection.

[0118] The threshold value Tth1 is a fixed value used to indicate the boundary between the period TC[m] of the residual vibration occurring in the ejection part D[m] when the ejection state of the ejection part D[m] is normal and the period TC[m] of the residual vibration occurring in the ejection part D[m] when bubbles are mixed into the cavity CV of the ejection part D[m].

[0119] Threshold Tth2 is a value larger than threshold Tth1, and is a fixed value used to indicate the boundary between the period TC[m] of residual vibration occurring in the ejection part D[m] when the ejection state of the ejection part D[m] is normal and the period TC[m] of residual vibration occurring in the ejection part D[m] when foreign matter is attached near the nozzle N of the ejection part D[m].

[0120] Threshold value Tth3 is a value larger than threshold value Tth2, and is a fixed value used to indicate the boundary between period TC[m] of residual vibration occurring in ejection portion D[m] when foreign matter adheres near nozzle N of ejection portion D[m] and period TC[m] of residual vibration occurring in ejection portion D[m] after ink viscosity increases in cavity CV of ejection portion D[m].

[0121] In this embodiment, when the period TC[m] satisfies "Tth1≤TC[m]≤Tth2", the inspection unit 5 regards the ejection state of the ink in the ejection section D[m] as normal, and sets the value "1" indicating that the ejection state of the ink in the ejection section D[m] is normal to the inspection result information SH[m].

[0122] In addition, when the period TC[m] satisfies "TC[m]<Tth1", the inspection unit 5 regards that a discharge abnormality caused by bubbles has occurred in the discharge section D[m], and sets the value "2" indicating that a discharge abnormality caused by bubbles has occurred in the discharge section D[m] in the inspection result information SH[m].

[0123] In addition, when the period TC[m] satisfies "Tth2<TC[m]≤Tth3", the inspection unit 5 regards that a discharge abnormality caused by foreign matter adhesion has occurred in the discharge section D[m], and sets the value "3" indicating that a discharge abnormality caused by foreign matter adhesion has occurred in the discharge section D[m] in the inspection result information SH[m].

[0124] In addition, when the period TC[m] satisfies "Tth3<TC[m]", the inspection unit 5 regards that a discharge abnormality caused by thickening has occurred in the discharge portion D[m], and sets the value "4" indicating that a discharge abnormality caused by thickening has occurred in the discharge portion D[m] to the inspection result information SH[m].

[0125] 4. Reference examples

[0126] Refer to the following Figures 11 to 13 A reference example will be described.

[0127] Fig.11 1 is a timing chart showing an example of various signals supplied to the head unit 3 in the reference example.

[0128] like Fig.11 As shown, the reference example is different from the above-mentioned embodiment in that: a drive signal Com-W is supplied to the head unit 3 instead of the drive signal Com; a latch signal LAT-W is supplied to the head unit 3 instead of the latch signal LAT; a designation signal SI-W is supplied to the head unit 3 instead of the designation signal SI; and a period designation signal Tsig-W is supplied to the head unit 3 instead of the period designation signal Tsig. In addition, the reference example is different from the above-mentioned embodiment in that the operation period of the inkjet printer 1 is divided into a plurality of unit periods TP-W. It should be noted that, in the reference example, the drive signal Com-W supplied to the ejection portion D[m] is referred to as a supply drive signal Vin-W[m].

[0129] In the reference example, the latch signal LAT-W includes a plurality of pulses PLL-W. Therefore, the control unit 2 according to the reference example defines the unit period TP-W as a period from a rising edge of the pulse PLL-W to a rising edge of the next pulse PLL-W.

[0130] It should be noted that, hereinafter, the kth unit period TP-W in the operation period of the inkjet printer 1 involved in the reference example is referred to as the unit period TP-W(k). In addition, hereinafter, the pulse PLL-W at the beginning of a predetermined unit period TP-W(k) among the plurality of pulses PLL-W included in the latch signal LAT-W is referred to as the pulse PLL-W(k). In addition, hereinafter, the supply drive signal Vin-W[m] supplied to the ejection portion D[m] within the unit period TP-W(k) is referred to as the supply drive signal Vin-W[m](k).

[0131] In addition, in the reference example, the period designation signal Tsig-W has a pulse PLT1-W and a pulse PLT2-W. Therefore, the control unit 2 involved in the reference example divides the unit period TP-W into a control period TS1-W from the rising edge of the pulse PLL-W to the rising edge of the pulse PLT1-W, a control period TS2-W from the rising edge of the pulse PLT1-W to the rising edge of the pulse PLT2-W, and a control period TS3-W from the rising edge of the pulse PLT2-W to the rising edge of the pulse PLL-W.

[0132] It should be noted that, hereinafter, the pulse PLT1-W set in the unit period TP-W(k) is referred to as the pulse PLT1-W(k), and the pulse PLT2-W set in the unit period TP-W(k) is referred to as the pulse PLT2-W(k).

[0133] In addition, in the reference example, the driving signal Com-W includes the driving signal Com-AW and the driving signal Com-BW.

[0134] The drive signal Com-AW is a signal having a waveform PA1 in each unit period TP-W. The drive signal Com-BW is a signal having a waveform PB in a control period TS1-W in each unit period TP-W, maintaining a reference potential V0 in a control period TS2-W in each unit period TP-W, and having a waveform PC in a control period TS3-W in each unit period TP-W.

[0135] In addition, before each unit period TP-W, the control unit 2 involved in the reference example synchronizes the designated signal SI-W with the clock signal CL and supplies it to the connection state designation circuit 34. Here, the designated signal SI-W includes M individual designated signals Sd-W[1] to Sd-W[M] corresponding one-to-one to the M ejection units D[1] to D[M]. Among them, the individual designated signal Sd-W[m] specifies the driving form of the ejection unit D[m] within the unit period TP-W. Specifically, the individual designated signal Sd-W[m] can take any of the three values ​​of "1" which designates the ejection unit D[m] as the printing ejection unit DP, "2" which designates the ejection unit D[m] as the dot non-forming ejection unit DN, and "3" which designates the ejection unit D[m] as the inspection object ejection unit DS.

[0136] Fig.12 This is an explanatory diagram showing an example of the operation of the decoder DC[m] involved in the reference example.

[0137] like Fig.12As shown, when the individual designation signal Sd-W[m] indicates that the ejection unit D[m] is designated as the value "1" of the printing ejection unit DP within the unit period TP-W, similarly to the above-mentioned embodiment, the decoder DC[m] involved in the reference example sets the connection state designation signal Qa[m] to a high level within the entire unit period TP-W.

[0138] In addition, when the individual designation signal Sd-W[m] indicates that the ejection portion D[m] is designated as the value "2" of the point non-forming ejection portion DN within the unit period TP-W, similarly to the above-mentioned embodiment, the decoder DC[m] involved in the reference example sets the connection state designation signal Qa[m], the connection state designation signal Qb[m], the connection state designation signal Qc[m] and the connection state designation signal Qs[m] to a low level within the entire unit period TP-W.

[0139] Furthermore, when the individual designation signal Sd-W[m] indicates the value "3" that the ejection unit D[m] is designated as the test target ejection unit DS in the unit period TP-W, the decoder DC[m] according to the reference example sets the connection state designation signal Qb[m] to a high level in the control period TS1-W and the control period TS3-W in the unit period TP-W, and sets the connection state designation signal Qs[m] to a high level in the control period TS2-W in the unit period TP-W. In this case, the switch Wb[m] is turned on in the control period TS1-W and the control period TS3-W in the unit period TP-W, and the switch Ws[m] is turned on in the control period TS2-W in the unit period TP-W. Therefore, the ejection unit D[m] designated as the ejection unit DS to be inspected is driven by the supply drive signal Vin-W[m] having the waveform PB during the control period TS1-W, and as a result, the vibration generated in the ejection unit D[m] remains even during the control period TS2-W. In addition, when the vibration remains in the ejection unit D[m] during the control period TS2-W, the potential of the upper electrode Zu[m] provided in the ejection unit D[m] changes. Then, the detection circuit 33 detects the potential of the upper electrode Zu[m] that changes in accordance with the vibration remaining in the ejection unit D[m] as the detection potential signal VX[m] during the control period TS2-W through the switch Ws[m].

[0140] As can be seen from this, in the reference example, in the control period TS1-W in the unit period TP-W, the inspection object drive process of driving the inspection object ejection part DS as the inspection drive ejection part DS1 is performed, and in the control period TS2-W in the unit period TP-W, the residual vibration detection process of driving the inspection object ejection part DS as the vibration detection ejection part DS2 is performed. Therefore, in the reference example, the unit period TP-W requires at least the total time length of the time for driving the inspection drive ejection part DS1 by the waveform PB and the time for detecting the detection potential signal VX[m] from the vibration detection ejection part DS2. On the other hand, for the unit period TP involved in the embodiment, only one of the time for driving the inspection drive ejection part DS1 by the waveform PB or the time for detecting the detection potential signal VX[m] from the vibration detection ejection part DS2 is required. Therefore, the unit period TP-W involved in the reference example is longer in time length than the unit period TP involved in the embodiment. It should be noted that in the reference example, as an example, it is assumed that the unit period TP-W has a time length twice that of the unit period TP.

[0141] Fig.13 A timing diagram showing an example of supply drive signals Vin-W[m] to Vin-W[m+2] supplied to multiple ejection parts D[m] to D[m+2] provided in the head unit 3 within multiple unit periods TP-W(k) to TP-W(k+1) involved in the reference example.

[0142] It should be noted that in Fig.13 In the above, it is assumed that the variable m is a natural number satisfying "1≤m≤M-2". In addition, hereinafter, the individual designation signal Sd-W[m] that designates the action of the ejection unit D[m] within the unit period TP-W(k) is referred to as the individual designation signal Sd-W[m](k).

[0143] Then, in Fig.13 In the above, it is assumed that the inkjet printer 1 of the reference example performs two ejection status inspection processes on two ejection units D, namely, the ejection unit D[m] and the ejection unit D[m+1], within two unit periods TP-W, namely, the unit period TP-W(k) and the unit period TP-W(k+1). Fig.13 In the diagram, it is assumed that the unit period TP-W(k) is composed of the unit period TP(k) and the unit period TP(k+1), and the unit period TP-W(k+1) is composed of the unit period TP(k+2) and the unit period TP(k+3).

[0144] In addition, Fig.13In the above, it is assumed that the inkjet printer 1 involved in the reference example drives the ejection unit D that is not the object of the ejection status inspection process among the three ejection units D, namely, the ejection unit D[m], the ejection unit D[m+1] and the ejection unit D[m+2], as the printing ejection unit DP.

[0145] like Fig.13 As shown, the control unit 2 of the reference example generates a separate designation signal Sd-W[m](k) for designating the ejection unit D[m] as the ejection unit DS to be inspected within the unit period TP-W(k). Thus, the inkjet printer 1 of the reference example performs the ejection state inspection process with the ejection unit D[m] as the object within the unit period TP-W(k).

[0146] In addition, the control unit 2 according to the reference example generates the individual designation signal Sd-W[m+1](k+1) for designating the ejection unit D[m+1] as the ejection unit DS to be inspected within the unit period TP-W(k+1). Thus, the inkjet printer 1 according to the reference example performs the ejection state inspection process with the ejection unit D[m+1] as the object within the unit period TP-W(k+1).

[0147] As can be seen from this, according to the reference example, when the ejection state inspection process for one ejection unit D is being executed in one unit period TP-W, the ejection state inspection process for another ejection unit D cannot be executed in one unit period TP-W. Therefore, according to the reference example, the ejection state inspection process is executed twice in two unit periods TP-W(k) and TP-W(k+1) corresponding to the period from the unit period TP(k) to the unit period TP(k+3).

[0148] In contrast, in the above embodiment, when the inspection object drive process is being performed with one ejection unit D as the object within one unit period TP, the residual vibration detection process can be performed with other ejection units D as the object within one unit period TP. Therefore, in the above embodiment, the ejection state inspection process is performed three times within the period from the unit period TP(k) to the unit period TP(k+3). That is, according to the embodiment, when the ejection state inspection process is performed multiple times with multiple ejection units D as the object, the time required for the multiple ejection state inspection processes can be shortened compared to the reference example.

[0149] In addition, if Fig.13As shown, the control unit 2 according to the reference example generates a separate designation signal Sd-W[m+1](k) for designating the ejection unit D[m+1] as the printing ejection unit DP and a separate designation signal Sd-W[m+2](k) for designating the ejection unit D[m+2] as the printing ejection unit DP within the unit period TP-W(k). As a result, the inkjet printer 1 according to the reference example forms two dots Dt by the ejection unit D[m+1] and the ejection unit D[m+2] within the unit period TP-W(k).

[0150] In addition, the control unit 2 according to the reference example specifies the ejection unit D[m] as the individual designation signal Sd-W[m](k+1) of the printing ejection unit DP and specifies the ejection unit D[m+2] as the individual designation signal Sd-W[m+2](k+1) of the printing ejection unit DP within the unit period TP-W(k+1). Thus, the inkjet printer 1 according to the reference example forms two dots Dt by the ejection unit D[m] and the ejection unit D[m+2] within the unit period TP-W(k+1).

[0151] It can be seen that according to the reference example, Fig.13 As shown, in the unit period TP-W(k) and the unit period TP-W(k+1) corresponding to the period from the unit period TP(k) to the unit period TP(k+3), four points Dt are formed by three ejection parts D[m] to D[m+2]. Figure 8 As shown, six dots Dt are formed during the period from the unit period TP(k) to the unit period TP(k+3). Therefore, according to the embodiment, the time required to form a desired number of dots Dt can be shortened compared to the reference example, and the printing process can be accelerated.

[0152] 5. Summary of implementation methods

[0153] In summary, the inkjet printer 1 involved in the present embodiment is characterized by comprising: an ejection unit D[m] that ejects ink according to the supply of a drive signal Com; a supply circuit 31 that supplies the drive signal Com to the ejection unit D[m]; and a detection circuit 33 that detects vibration in the ejection unit D[m], the supply circuit 31 supplies the drive signal Com-B having a waveform PB in the drive signal Com to the ejection unit D[m] within a unit period TP(k), the unit period TP(k) being started by a pulse PLL(k) among a plurality of pulses PLL included in a latch signal LAT supplied to the supply circuit 31, and being ended by a pulse PLL(k+1) among a plurality of pulses PLL that is set next to the pulse PLL(k), the detection circuit 33 detecting vibration remaining in the ejection unit D[m] within a unit period TP(k+1), the unit period TP(k+1) being started by a pulse PLL(k+1), and being ended by a pulse PLL(k+2) among a plurality of pulses PLL that is set next to the pulse PLL(k+1).

[0154] As can be seen from the above, according to the present embodiment, since the ejection unit D[m] is driven within one unit period TP and the vibration is detected from the ejection unit D[m] within another unit period TP following the one unit period TP, the time length of the unit period TP can be shortened compared to a configuration in which both the ejection unit D[m] is driven and the vibration is detected from the ejection unit D[m] within one unit period TP. Therefore, according to the present embodiment, it is possible to speed up the printing process of ejecting ink from the ejection unit D[m] to form an image on the recording paper PP.

[0155] In addition, in the inkjet printer 1 involved in the present embodiment, it is characterized in that, at a timing corresponding to each unit period TP among a plurality of unit periods TP specified by a plurality of pulses PLL, a designated signal SI is supplied to the supply circuit 31 for specifying whether ink is ejected from the ejection portion D[m] in each unit period TP among the plurality of unit periods TP, and the supply circuit 31 supplies the drive signal Com to the ejection portion D[m] based on the designated signal SI in each unit period TP among the plurality of unit periods TP.

[0156] In addition, in the inkjet printer 1 involved in this embodiment, it is characterized in that the detection circuit 33 detects the vibration remaining in the ejection part D[m] within the control period TS2 in the unit period TP(k+1), and the control period TS2 is started by the pulse PLT1(k+1) included in the period designation signal Tsig supplied to the supply circuit 31, and ends with the pulse PLT2(k+1) included in the period designation signal Tsig.

[0157] In addition, in the inkjet printer 1 involved in the present embodiment, it is characterized in that the drive signal Com includes a drive signal Com-C supplied to the ejection portion D[m] during at least a portion of the unit period TP(k+1), and the drive signal Com-B shows a reference potential V0 at the timing of supplying the pulse PLL(k+1) to the supply circuit 31, and the drive signal Com-C maintains the reference potential V0 during the control period TS1 of at least the timing from the timing of supplying the pulse PLL(k+1) to the supply circuit 31 to the timing of the start of the control period TS2 in the unit period TP(k+1).

[0158] Therefore, according to the present embodiment, at the timing when the unit period TP(k+1) starts, the signal supplied to the ejection unit D[m] can be switched from the drive signal Com-B to the drive signal Com-C. Therefore, according to the present embodiment, in order to drive the ejection unit D[m] within the unit period TP(k), the drive signal Com-B can be supplied to the ejection unit D[m], and in order to detect vibration from the ejection unit D[m] within the unit period TP(k+1), the drive signal Com-C can be supplied to the ejection unit D[m].

[0159] In the inkjet printer 1 according to the present embodiment, the waveform PB is a waveform that changes from the potential VB to the reference potential V0 after changing from the reference potential V0 to the potential VB.

[0160] In addition, in the inkjet printer 1 involved in the present embodiment, it is characterized in that the ejection part D[m] includes: a piezoelectric element PZ[m] driven by a drive signal Com; a cavity CV filled with ink and whose volume changes according to the driving of the piezoelectric element PZ[m]; and a nozzle N that ejects the ink in the cavity CV according to the change in the volume of the cavity CV, and the volume of the cavity CV when the drive signal Com-B supplied to the piezoelectric element PZ[m] indicates a reference potential V0 is larger than the volume of the cavity CV when the drive signal Com-B supplied to the piezoelectric element PZ[m] indicates a potential VB.

[0161] Therefore, according to the present embodiment, when the discharge portion D[m] is driven by the change from the potential VB to the reference potential V0 in the waveform PB of the drive signal Com-B, it is possible to prevent ink from being discharged from the discharge portion D[m].

[0162] In the inkjet printer 1 according to the present embodiment, the time for the waveform PB to change from the reference potential V0 to the potential VB is longer than the time for the waveform PB to change from the potential VB to the reference potential V0.

[0163] Therefore, according to the present embodiment, when the ejection portion D[m] is driven by the change from the potential VB to the reference potential V0 in the waveform PB of the drive signal Com-B, the ejection portion D[m] can be caused to vibrate greatly. In addition, according to the present embodiment, when the ejection portion D[m] is driven by the change from the reference potential V0 to the potential VB in the waveform PB of the drive signal Com-B, ink can be prevented from being ejected from the ejection portion D[m].

[0164] In addition, in the inkjet printer 1 involved in this embodiment, it is characterized in that the drive signal Com has multiple drive waveforms including a waveform PB, and within a unit period TP specified by multiple pulses PLL, the time length GB from the end of the waveform PB to the end of one unit period TP is shorter than the time length from the end of all drive waveforms except the waveform PB to the end of one unit period TP.

[0165] Therefore, according to this embodiment, compared with a form in which the time length GB from the end of the waveform PB to the end of a unit period TP is longer than the time length from the end of other driving waveforms to the end of a unit period TP, the time length from the timing of the end of the driving of the ejection portion D[m] by the waveform PB to the timing of starting to detect the vibration remaining in the ejection portion D[m] can be shortened, and the vibration remaining in the ejection portion D[m] can be detected more accurately.

[0166] B. Modification

[0167] The above methods can be modified in many ways. Specific modified forms are illustrated below. Two or more forms arbitrarily selected from the following examples can be appropriately combined within the scope of non-contradiction. It should be noted that in the modified examples illustrated below, the elements with the same effects and functions as the implementation methods will be marked with the reference numerals in the above description to appropriately omit their detailed descriptions.

[0168] Modification 1

[0169] In the above embodiment, the signal of the control period TS2 for detecting the detection potential signal VX[m] from the ejection unit D[m] in the predetermined unit period TP, that is, the period designation signal Tsig is exemplified as a signal for distinguishing the unit period TP, but the present invention is not limited to such a form. The unit period TP may also be distinguished by a signal other than the period designation signal Tsig.

[0170] Fig.14 It is a block diagram showing an example of the configuration of the head unit 3Z according to the present modification.

[0171] like Fig.14As shown, the head unit 3Z is different from the head unit 3 involved in the embodiment in that it is provided with a connection state designation circuit 34Z instead of the connection state designation circuit 34. The connection state designation circuit 34Z is different from the connection state designation circuit 34 involved in the embodiment in that it is supplied with a change signal CH and a designation signal SI-Z instead of the designation signal SI.

[0172] Fig.15 1 is a timing chart showing an example of various signals supplied to the head unit 3Z in this modification.

[0173] like Fig.15 As shown, in this modification, the head unit 3Z is different from the head unit 3 involved in the embodiment in that: a change signal CH is supplied; a drive signal Com-Z is supplied instead of the drive signal Com; and a designation signal SI-Z is supplied instead of the designation signal SI.

[0174] The change signal CH has a plurality of pulses PLC corresponding to a plurality of unit periods TP. The control unit 2 involved in this modification divides the unit period TP(k) into a control period TQ1 from the rising edge of pulse PLL(k) to the rising edge of pulse PLC and a control period TQ2 from the rising edge of pulse PLC to the rising edge of pulse PLL(k+1). It should be noted that pulse PLC is an example of a "change pulse". In addition, in the following, control period TQ1 and control period TQ2 are sometimes collectively referred to as control period TQ.

[0175] The drive signal Com-Z includes the drive signal Com-AZ, the drive signal Com-B and the drive signal Com-C. It should be noted that, in this modification, the drive signal Com-Z supplied to the ejection portion D[m] is referred to as the supply drive signal Vin-Z[m]. In addition, in this modification, the drive signal Com-Z supplied to the ejection portion D[m] within the unit period TP(k) is referred to as the supply drive signal Vin-Z[m](k).

[0176] The drive signal Com-AZ has a waveform PA1 provided in the control period TQ1 and a waveform PA2 provided in the control period TQ2 .

[0177] As described above, the waveform PA1 is a waveform that returns from the reference potential V0 to the reference potential V0 via the potential VL1 having a lower potential than the reference potential V0 and the potential VH1 having a higher potential than the reference potential V0. In this modification, when the supply drive signal Vin-Z[m] having the waveform PA1 is supplied to the ejection portion D[m], the shape of the waveform PA1 is adjusted so that the ink corresponding to the ink amount ξ1 is ejected from the ejection portion D[m].

[0178] The waveform PA2 is a waveform that returns from the reference potential V0 to the reference potential V0 via the potential VL2 having a lower potential than the reference potential V0 and the potential VH2 having a higher potential than the reference potential V0. In this modification, when the supply drive signal Vin-Z[m] having the waveform PA2 is supplied to the ejection portion D[m], the shape of the waveform PA2 is adjusted so that the ink corresponding to the ink amount ξ2 is ejected from the ejection portion D[m].

[0179] It should be noted that, hereinafter, the waveform including the waveform PA1 and the waveform PA2 of the drive signal Com-AZ in each unit period TP may be referred to as a waveform PA.

[0180] Here, the ink amount ξ1 is the ink amount corresponding to the middle point Dt2. In addition, the ink amount ξ2 is the ink amount that is less than the ink amount ξ1 and is corresponding to the small dot Dt3 that is smaller than the middle point Dt2. In addition, the total amount of the ink amount ξ1 and the ink amount ξ2 is the ink amount corresponding to the large dot Dt1 that is larger than the middle point Dt2. Each ejection unit D[m] of the inkjet printer 1 involved in this variant can form any one of the three types of dots Dt, namely, the large dot Dt1, the middle dot Dt2, and the small dot Dt3, within each unit period TP. Therefore, according to the inkjet printer 1 involved in this variant, compared with a form in which each ejection unit D[m] can only form one type of dot Dt within each unit period TP, a high-definition image can be formed.

[0181] It should be noted that, in the present modification, the waveform PA2 is arranged so that the time length GA2 from the end of the waveform PA2 to the end of the unit period TP in which the waveform PA2 is provided is longer than the time length GB.

[0182] In addition, before each unit period TP, the control unit 2 according to the present modification synchronizes the designation signal SI-Z with the clock signal CL and supplies it to the connection state designation circuit 34Z. Here, the designation signal SI-Z includes M individual designation signals Sd-Z[1] to Sd-Z[M] corresponding one-to-one to the M ejection units D[1] to D[M]. Among them, the individual designation signal Sd-Z[m] designates the driving mode of the ejection unit D[m] in the unit period TP.

[0183] Specifically, in this modification, the individual designation signal Sd-Z[m] can take any one of six values ​​in each unit period TP: a value "1" for designating the ejection unit D[m] as the large dot forming ejection unit DP1, a value "2" for designating the ejection unit D[m] as the medium dot forming ejection unit DP2, a value "3" for designating the ejection unit D[m] as the small dot forming ejection unit DP3, a value "4" for designating the ejection unit D[m] as the dot non-forming ejection unit DN, a value "5" for designating the ejection unit D[m] as the inspection drive ejection unit DS1, and a value "6" for designating the ejection unit D[m] as the vibration detection ejection unit DS2. Here, the large dot forming ejection unit DP1 is an ejection unit D that ejects the ink of the total amount of ink amount ξ1 and ink amount ξ2 from the nozzle N in the unit period TP to form the large dot Dt1 on the recording paper PP. The middle dot forming ejection portion DP2 is an ejection portion D that ejects ink of an ink amount ξ1 from the nozzle N in the unit period TP to form a middle dot Dt2 on the recording paper PP. The small dot forming ejection portion DP3 is an ejection portion D that ejects ink of an ink amount ξ2 from the nozzle N in the unit period TP to form a small dot Dt3 on the recording paper PP.

[0184] Fig.16 It is a block diagram showing an example of the configuration of the connection state designation circuit 34Z.

[0185] like Fig.16 As shown, the connection state designation circuit 34Z is different from the connection state designation circuit 34 involved in the embodiment in that it has M decoders DCz[1] to DCz[M] instead of M decoders DC[1] to DC[M]. The individual designation signal Sd-Z[1] to Sd-Z[M] is supplied serially to the transmission circuit SR[1]. In addition, the individual designation signal Sd-Z[m] supplied to the transmission circuit SR[1] is sequentially transmitted from the transmission circuit SR[1] to the transmission circuit SR[m] in synchronization with the clock signal CL through m transmission circuits SR[1] to SR[m] among the M transmission circuits SR[1] to SR[M]. In addition, the latch circuit LT[m] latches the individual designation signal Sd-Z[m] supplied to the transmission circuit SR[m] at the timing when the pulse PLL of the latch signal LAT rises to the high level. In addition, the decoder DCz[m] generates a connection state designation signal Qa[m], a connection state designation signal Qb[m], a connection state designation signal Qc[m] and a connection state designation signal Qs[m] based on the individual designation signal Sd-Z[m], the change signal CH, the latch signal LAT and the period designation signal Tsig.

[0186] Fig.17 It is an explanatory diagram showing an example of the operation of the decoder DCz[m] involved in this modification.

[0187] like Fig.17As shown, when the individual designation signal Sd-Z[m] indicates the value "1" that the ejection unit D[m] is designated as the large dot forming ejection unit DP1 within the unit period TP, the decoder DCz[m] sets the connection state designation signal Qa[m] to a high level throughout the unit period TP. In this case, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveforms PA1 and PA2, and ejects the ink of the total amount of ink amount ξ1 and ink amount ξ2 to form the large dot Dt1.

[0188] Furthermore, when the individual designation signal Sd-Z[m] indicates the value "2" that designates the ejection unit D[m] as the midpoint forming ejection unit DP2 in the unit period TP, the decoder DCz[m] sets the connection state designation signal Qa[m] to a high level in the control period TQ1. In this case, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA1, and ejects ink of the ink amount ξ1 to form the midpoint Dt2.

[0189] Furthermore, when the individual designation signal Sd-Z[m] indicates the value "3" that designates the ejection unit D[m] as the dot forming ejection unit DP3 in the unit period TP, the decoder DCz[m] sets the connection state designation signal Qa[m] to a high level in the control period TQ2. In this case, the ejection unit D[m] is driven by the supply drive signal Vin[m] having the waveform PA2, and ejects ink of the ink amount ξ2 to form a dot Dt3.

[0190] It should be noted that when the individual designated signal Sd-Z[m] designates the ejection unit D[m] as the point non-forming ejection unit DN within the unit period TP, when the ejection unit D[m] is designated as the inspection drive ejection unit DS1, and when the ejection unit D[m] is designated as the vibration detection ejection unit DS2, the ejection unit D[m] operates in the same manner as in the above-mentioned embodiment.

[0191] Fig.18 1 is a timing chart showing an example of supply drive signals Vin-Z[m] to Vin-Z[m+2] supplied to a plurality of ejection portions D[m] to D[m+2] provided in the head unit 3Z within a plurality of unit periods TP(k) to TP(k+3).

[0192] It should be noted that in Fig.18 In the above, it is assumed that the variable m is a natural number satisfying "1≤m≤M-2". In addition, hereinafter, the individual designation signal Sd-Z[m] that designates the operation of the ejection unit D[m] within the unit period TP(k) is referred to as the individual designation signal Sd-Z[m](k).

[0193] In addition, Fig.18In the above, it is assumed that three ejection state inspection processes are performed on three ejection units D, namely, ejection unit D[m], ejection unit D[m+1], and ejection unit D[m+2], within four unit periods TP, namely, unit period TP(k), unit period TP(k+1), unit period TP(k+2), and unit period TP(k+3). Fig.18 In the above description, it is assumed that a discharge portion D[m], a discharge portion D[m+1], and a discharge portion D[m+2] which are not the objects of the discharge state inspection process are driven as the large dot forming discharge portion DP1.

[0194] The control unit 2 according to this modification generates a separate designation signal Sd-Z[m](k) for designating the ejection unit D[m] as the inspection drive ejection unit DS1 within the unit period TP(k), and generates a separate designation signal Sd-Z[m](k+1) for designating the ejection unit D[m] as the vibration detection ejection unit DS2 within the unit period TP(k+1). Fig.18 As shown, the inkjet printer 1 according to this modification example supplies the drive signal Com-B having the waveform PB as the supply drive signal Vin-Z[m](k) to the ejection portion D[m] within the unit period TP(k), and supplies the drive signal Com-C having the waveform PC as the supply drive signal Vin-Z[m](k+1) to the ejection portion D[m] within the unit period TP(k+1). As a result, the inkjet printer 1 according to this modification example performs the residual vibration detection process for the ejection portion D[m] within the unit period TP(k) after performing the inspection target drive process for the ejection portion D[m] within the unit period TP(k). In addition, after the inkjet printer 1 according to the present modification performs the inspection target drive processing with respect to the ejection unit D[m+1] as the target in the unit period TP(k+1), the residual vibration detection processing with respect to the ejection unit D[m+1] as the target in the unit period TP(k+2) is performed, thereby performing the ejection state inspection processing with respect to the ejection unit D[m+1] as the target. In addition, after the inkjet printer 1 according to the present modification performs the inspection target drive processing with respect to the ejection unit D[m+2] as the target in the unit period TP(k+2), the residual vibration detection processing with respect to the ejection unit D[m+2] as the target in the unit period TP(k+3) is performed, thereby performing the ejection state inspection processing with respect to the ejection unit D[m+2] as the target.

[0195] In summary, the inkjet printer 1 involved in this modified example is characterized by comprising: a discharge unit D[m] that discharges ink according to the supply of a drive signal Com-Z; a supply circuit 31 that supplies the drive signal Com-Z to the discharge unit D[m]; and a detection circuit 33 that detects vibration in the discharge unit D[m], wherein the supply circuit 31 supplies the drive signal Com-B having a waveform PB in the drive signal Com-Z to the discharge unit D[m] within a unit period TP(k), wherein the unit period TP(k) is started by a pulse PLL(k) among a plurality of pulses PLL included in a latch signal LAT supplied to the supply circuit 31, and ends by a pulse PLL(k+1) set next to the pulse PLL(k) among the plurality of pulses PLL, and the detection circuit 33 detects vibration remaining in the discharge unit D[m] within a unit period TP(k+1), wherein the unit period TP(k+1) is started by a pulse PLL(k+1) and ends by a pulse PLL(k+1) set next to the pulse PLL(k+1) among the plurality of pulses PLL. The pulse PLL (k+2) ends, and at a timing corresponding to each unit period TP in a plurality of unit periods TP specified by the plurality of pulses PLL, a designated signal SI-Z is supplied to the supply circuit 31 for specifying whether ink is ejected from the ejection portion D[m] in each unit period TP in the plurality of unit periods TP, and a change signal CH having a plurality of pulses PLC for dividing each unit period TP in the plurality of unit periods TP into a plurality of control periods TQ is supplied. The designated signal SI-Z supplied to the supply circuit 31 at a timing corresponding to one unit period TP in the plurality of unit periods TP specifies whether ink is ejected from the ejection portion D[m] in each control period TQ in the plurality of control periods TQ constituting one unit period TP. The supply circuit 31 supplies a drive signal Com-Z to the ejection portion D[m] based on the designated signal SI-Z supplied to the supply circuit 31 at a timing corresponding to one unit period TP in each control period TQ in the plurality of control periods TQ constituting one unit period TP.

[0196] As can be seen from the above, according to this modification, since the ejection unit D[m] is driven within one unit period TP and the vibration is detected from the ejection unit D[m] within another unit period TP following the one unit period TP, the time length of the unit period TP can be shortened compared to a configuration in which both the ejection unit D[m] is driven and the vibration is detected from the ejection unit D[m] within one unit period TP. Therefore, according to this modification, it is possible to speed up the printing process in which the ejection unit D[m] ejects ink to form an image on the recording paper PP.

[0197] Modification 2

[0198] In the above-mentioned embodiment and modification 1, the case where the inspection unit 5 is provided separately from the head unit 3 is illustrated for explanation, but the present invention is not limited to such a form. The inspection unit 5 may also be provided in the head unit 3. In this case, compared with the form where the inspection unit 5 is provided outside the head unit 3, the possibility of noise mixing into the detection signal SK[m] supplied to the inspection unit 5 by the detection circuit 33 can be suppressed, thereby improving the accuracy of the inspection in the inspection unit 5.

[0199] Modification 3

[0200] In the above-mentioned embodiment and modification examples 1 and 2, it is assumed that the inkjet printer 1 has four head units 3, but the present invention is not limited to such a form. The inkjet printer 1 may be a printer having one or more and three or less head units 3, or a printer having five or more head units 3.

[0201] Modification 4

[0202] In the above-mentioned embodiment and Modifications 1 to 4, the case where the inkjet printer 1 is a serial printer is exemplified, but the present invention is not limited to such a form. The inkjet printer 1 may also be a so-called line printer in which a plurality of nozzles N are provided in the head unit 3 so as to extend in a range wider than the width of the recording paper PP.

Claims

1. A liquid ejection head, characterized in that: have: A discharge unit discharges liquid according to a driving signal; a supply unit that supplies the driving signal to the ejection unit; and a detection unit that detects vibration in the ejection unit, The supply unit supplies the inspection drive signal having the inspection waveform among the drive signals to the ejection unit in a first unit period, the first unit period being started by a first latch pulse among a plurality of latch pulses included in the latch signal supplied to the supply unit and being ended by a second latch pulse among the plurality of latch pulses provided next to the first latch pulse, The detection unit detects the vibration remaining in the ejection unit in a second unit period, the second unit period being started by the second latch pulse and ended by a third latch pulse provided next to the second latch pulse among the plurality of latch pulses.

2. The liquid ejection head according to claim 1, wherein: The supply unit is supplied with a designated signal designating whether or not the liquid is to be ejected from the ejection unit in each of the plurality of unit periods specified by the plurality of latch pulses at a timing corresponding to each of the plurality of unit periods. The supply unit supplies the drive signal to the discharge unit based on the designation signal in each of the plurality of unit periods.

3. The liquid ejection head according to claim 2, wherein: The supply unit is supplied with a change signal having a plurality of change pulses for dividing each of the plurality of unit periods into a plurality of control periods. The designation signal supplied to the supply unit at a timing corresponding to one of the plurality of unit periods designates whether or not the liquid is ejected from the ejection unit in each of the plurality of control periods constituting the one unit period. In each of a plurality of control periods constituting the one unit period, the supply section supplies the drive signal to the discharge section based on a designated signal supplied to the supply section at a timing corresponding to the one unit period.

4. The liquid ejection head according to claim 1, wherein: The detection unit detects the vibration remaining in the ejection unit during a detection period in the second unit period, and the detection period is started by a detection start pulse included in a period designation signal supplied to the supply unit and ended by a detection end pulse included in the period designation signal.

5. The liquid ejection head according to claim 4, wherein: The drive signal includes a detection drive signal supplied to the discharge portion during at least a portion of the second unit period. The inspection drive signal shows a first potential at a timing when the second latch pulse is supplied to the supply unit, The detection drive signal maintains the first potential during at least a period from a timing when the second latch pulse is supplied to the supply section to a timing when the detection period starts in the second unit period.

6. The liquid ejection head according to claim 5, wherein: The inspection waveform is a waveform that changes from the first potential to the second potential and then changes from the second potential to the first potential.

7. The liquid ejection head according to claim 6, wherein: The ejection portion comprises: a piezoelectric element driven by the driving signal; a pressure chamber filled with liquid and having a volume that changes according to the driving of the piezoelectric element; and a nozzle for ejecting liquid in the pressure chamber according to a change in the volume of the pressure chamber, The volume of the pressure chamber when the drive signal supplied to the piezoelectric element indicates the first potential is larger than the volume of the pressure chamber when the drive signal supplied to the piezoelectric element indicates the second potential.

8. The liquid ejection head according to claim 7, wherein: The time for the inspection waveform to change from the first potential to the second potential is longer than the time for the inspection waveform to change from the second potential to the first potential.

9. The liquid ejection head according to claim 1, wherein: The driving signal has a plurality of driving waveforms including the inspection waveform, During a unit period defined by the plurality of latch pulses, The length of time from the end of the inspection waveform to the end of the one unit period is shorter than the length of time from the end of all the drive waveforms except the inspection waveform among the plurality of drive waveforms to the end of the one unit period.

10. A liquid ejection device, characterized in that: have: A discharge unit discharges liquid according to a driving signal; a supply unit that supplies the driving signal to the ejection unit; and a detection unit that detects vibration in the ejection unit, The supply unit supplies the inspection drive signal having the inspection waveform among the drive signals to the ejection unit in a first unit period, the first unit period being started by a first latch pulse among a plurality of latch pulses included in the latch signal supplied to the supply unit and being ended by a second latch pulse among the plurality of latch pulses provided next to the first latch pulse, The detection unit detects the vibration remaining in the ejection unit in a second unit period, the second unit period being started by the second latch pulse and ended by a third latch pulse provided next to the second latch pulse among the plurality of latch pulses.

11. A method for controlling a liquid ejection head, characterized in that: The liquid ejection head comprises: A discharge unit discharges liquid according to a driving signal; a supply unit that supplies the driving signal to the ejection unit; and a detection unit that detects vibration in the ejection unit, In the control method, controlling the liquid ejection head so that the supply unit supplies the inspection drive signal having the inspection waveform among the drive signals to the ejection unit within a first unit period, the first unit period being started by a first latch pulse among a plurality of latch pulses included in a latch signal supplied to the supply unit and being ended by a second latch pulse among the plurality of latch pulses provided next to the first latch pulse; as well as The liquid ejection head is controlled so that the detection unit detects the vibration remaining in the ejection unit within a second unit period, and the second unit period starts with the second latch pulse and ends with a third latch pulse set next to the second latch pulse among the multiple latch pulses.

12. The method for controlling a liquid ejection head according to claim 11, wherein: supplying to the supply unit, at a timing corresponding to each of a plurality of unit periods defined by the plurality of latch pulses, a designated signal designating whether or not the liquid is to be ejected from the ejection unit in each of the plurality of unit periods, The liquid ejection head is controlled so that the supply section supplies the drive signal to the ejection section based on the designation signal in each of the plurality of unit periods.

13. The method for controlling a liquid ejection head according to claim 12, wherein: supplying the supply unit with a change signal having a plurality of change pulses for dividing each of the plurality of unit periods into a plurality of control periods, The designation signal supplied to the supply unit at a timing corresponding to one of the plurality of unit periods designates whether or not the liquid is ejected from the ejection unit in each of the plurality of control periods constituting the one unit period. The liquid ejection head is controlled so that, in each of a plurality of control periods constituting the one unit period, the supply section supplies the drive signal to the ejection section based on a designated signal supplied to the supply section at a timing corresponding to the one unit period.

14. The method for controlling a liquid ejection head according to claim 11, wherein: The liquid ejection head is controlled so that the detection unit detects the vibration remaining in the ejection unit during a detection period in the second unit period, and the detection period is started by a detection start pulse included in a period designation signal supplied to the supply unit, and ends by a detection end pulse included in the period designation signal.

15. The method for controlling a liquid ejection head according to claim 14, wherein: The drive signal includes a detection drive signal supplied to the discharge portion during at least a portion of the second unit period. The inspection drive signal shows a first potential at a timing when the second latch pulse is supplied to the supply unit, The detection drive signal maintains the first potential during at least a period from a timing when the second latch pulse is supplied to the supply section to a timing when the detection period starts in the second unit period.

16. The method for controlling a liquid ejection head according to claim 15, wherein: The inspection waveform is a waveform that changes from the first potential to the second potential and then changes from the second potential to the first potential.

17. The method for controlling a liquid ejection head according to claim 16, wherein: The ejection portion comprises: a piezoelectric element driven by the driving signal; a pressure chamber filled with liquid and having a volume that changes according to the driving of the piezoelectric element; and a nozzle for ejecting liquid in the pressure chamber according to a change in the volume of the pressure chamber, The volume of the pressure chamber when the drive signal supplied to the piezoelectric element indicates the first potential is larger than the volume of the pressure chamber when the drive signal supplied to the piezoelectric element indicates the second potential.

18. The method for controlling a liquid ejection head according to claim 17, wherein: The time for the inspection waveform to change from the first potential to the second potential is longer than the time for the inspection waveform to change from the second potential to the first potential.

19. The method for controlling a liquid ejection head according to claim 11, wherein: The drive signal has a plurality of drive waveforms including the inspection waveform, and within a unit period defined by the plurality of latch pulses, The length of time from the end of the inspection waveform to the end of the one unit period is shorter than the length of time from the end of all the drive waveforms except the inspection waveform among the plurality of drive waveforms to the end of the one unit period.

Images