JP2012245685A - Liquid jet apparatus, nozzle inspection method, and program thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control generation of a noise caused by a foreign object in the discharging inspection.SOLUTION: The discharge inspection to determine whether discharge of ink from the nozzle is performed based on the electrical alteration between a nozzle plate and an inspection electrode, caused when the ink is discharged from a nozzle of a head 62 toward an inspection electrode 72 with the voltage applied between a nozzle plate 63 and an inspection electrode 72 while making the both thereof facing each other. Then, the discharge processing before the inspection is performed to discharge a large amount of ink compared with the discharge inspection of the nozzle from the nozzle to the inspection electrode 72 ahead of the ejection inspection. As a result, the foreign object on the inspection electrode 72 is removed, or the distance of nozzle plate 63 and the foreign object can be separated by the ink discharged in the discharge processing before the inspection, and the noise caused in the foreign object in the discharge inspection can be controlled.

Description

  The present invention relates to a liquid ejection apparatus, a nozzle inspection method, and a program thereof.

  2. Description of the Related Art Conventionally, as a liquid ejection apparatus, a first electrode that sets a liquid discharged from a plurality of nozzles formed on a head to a first potential and a second electrode that is a second potential different from the first potential. Determining whether or not liquid has been discharged from each nozzle based on the electrical change between the two electrodes when the liquid is sequentially discharged from the plurality of nozzles toward the second electrode with a voltage applied to It has been known. The process for determining whether or not the liquid has been ejected from the nozzle in this way is referred to as nozzle inspection or ejection inspection.

  For example, in the liquid ejecting apparatus of Patent Document 1, liquid is ejected from a nozzle in a state where a predetermined potential difference is generated between the head and the inspection region, and nozzle inspection is performed based on the voltage change at this time. In addition, if the discharged liquid adheres to the head and the inspection region and is electrically connected to each other, a leakage current flows and the accuracy of nozzle inspection is reduced. For this reason, a short circuit between the head and the inspection region is suppressed by performing a process of separating the head and the inspection region.

JP 2007-136857 A

  Here, in addition to the leakage current due to the liquid, foreign matter such as dust attached to the electrode may cause noise, which may affect the accuracy of nozzle inspection. In the liquid ejecting apparatus described in Patent Document 1, even if the process of separating the distance between the head and the inspection area is performed, the generation of noise due to such foreign matter may not be suppressed.

  The present invention has been made in view of the above-described problems, and a main object thereof is to suppress the generation of noise due to foreign matter in the discharge inspection.

The liquid ejection device of the present invention is
A head having a plurality of nozzles for discharging liquid;
A first electrode in contact with the liquid;
A second electrode provided at a position capable of facing the first electrode;
Based on an electrical change between the two electrodes when liquid is ejected from the nozzle toward the second electrode in a state where the first electrode and the second electrode are opposed to each other and a voltage is applied between the two electrodes. Discharge inspection means for performing a discharge inspection for determining whether or not the liquid is discharged from the nozzle;
Processing means for performing a pre-inspection discharge process for discharging a large amount of liquid from the nozzle to the second electrode before the discharge inspection, compared to the time of the discharge inspection;
It is equipped with.

  In the liquid ejection apparatus according to the present invention, the electric current between the two electrodes when the liquid is ejected from the nozzle toward the second electrode in a state where the first electrode and the second electrode are opposed to each other and a voltage is applied between the two electrodes. A discharge inspection is performed to determine whether or not the liquid is discharged from the nozzle based on a change in the target. Before the discharge inspection, a pre-inspection discharge process is performed in which a larger amount of liquid is discharged from the nozzle to the second electrode than in the discharge inspection. In this way, when there is foreign matter on the second electrode, the foreign matter can be removed by the liquid ejected before the ejection test, or the distance between the first electrode and the foreign matter can be increased. Therefore, it is possible to suppress noise caused by foreign matter in the discharge inspection.

  In the liquid ejection apparatus according to the aspect of the invention, the processing unit may perform the pre-inspection ejection process in a state where no voltage is applied between the first electrode and the second electrode. Here, if the liquid ejected from the nozzle has an electric charge, a mist having an electric charge is generated from the ejected liquid, which may adhere to the periphery of the first electrode, for example, and contaminate it. Therefore, by performing the pre-inspection discharge process without applying a voltage between the first electrode and the second electrode, the liquid discharged in the pre-inspection discharge process is less likely to have a charge. Dirt can be suppressed.

  In the liquid ejection apparatus according to the aspect of the invention, the processing unit may be a unit that ejects liquid from the nozzle into a region facing the first electrode in the ejection inspection in the second electrode in the pre-inspection ejection process. Good. Here, a foreign substance in a region facing the first electrode in the discharge inspection among the second electrodes during the discharge inspection tends to cause noise. Therefore, it is easy to suppress noise caused by foreign matter in the discharge inspection by discharging the liquid into this region.

  In the liquid ejection apparatus according to the aspect of the invention, the head can eject a plurality of types of liquid from the nozzle, and the processing unit removes a liquid that is most difficult to dry out of the plurality of types of liquid in the pre-inspection ejection process. It may be a means for discharging liquid from the nozzle to the second electrode. In this way, it is possible to suppress foreign matter from adhering to the liquid ejected by the pre-inspection ejection process and causing noise as compared with the case of ejecting the liquid that is most difficult to dry. The liquid that is most difficult to dry is the liquid with the smallest moisture content compared to other liquids, the liquid with the least amount of moisture evaporation per unit time when compared with the same amount, and the moisture content is the lowest. It may be any of small liquids. Note that the liquid excluding the liquid that is most difficult to dry out of the plurality of types of liquids means one or more types of liquids among the liquids other than the liquid that is most difficult to dry out of the plurality of types of liquids. For example, as the liquid excluding the liquid that is most difficult to dry out of a plurality of types of liquids, only the liquid that is most easily dried may be ejected.

  In the liquid ejection apparatus according to the present invention, the liquid ejection apparatus includes a moving unit that relatively moves the head and the second electrode, and the processing unit performs the ejection test on the second electrode in the ejection test. It is good also as a means to discharge a liquid from the said nozzle with the movement by the said moving means so that a liquid may spread over the whole area | region facing a 1st electrode. In this way, the liquid is discharged so that the liquid spreads over the entire area facing the first electrode in the discharge inspection during the discharge inspection. Or the distance between the first electrode and the foreign material can be increased. For this reason, it becomes easy to suppress the noise resulting from the foreign material in a discharge inspection.

  The liquid ejection apparatus of the present invention further includes a foreign matter detection means for detecting the presence of foreign matter on the second electrode, and the processing means detects that the foreign matter is present on the second electrode by the foreign matter detection means. Sometimes, it may be a means for performing the pre-inspection ejection process. In this way, since the pre-inspection ejection process is performed when it is detected that there is a foreign material, noise caused by the foreign material in the ejection test can be efficiently suppressed.

  In the liquid ejection apparatus according to the aspect of the invention, the foreign matter detection unit may perform both operations when the liquid is not ejected from the plurality of nozzles in a state where the first electrode and the second electrode are opposed to each other and a voltage is applied between the two electrodes. It may be a means for determining the presence or absence of noise based on an electrical change between the electrodes and detecting that there is a foreign object in the second electrode when an affirmative determination is made. In this way, a foreign object can be detected based on the presence or absence of noise.

  In the liquid ejection apparatus of the present invention, the second electrode may be a flat electrode. In the case where the second electrode has a flat plate shape, foreign matters such as dust are more likely to adhere as compared with, for example, a mesh electrode, and therefore, the significance of applying the present invention is high.

The nozzle inspection method of the present invention includes:
A head having a plurality of nozzles for discharging liquid, a first electrode in contact with the liquid,
A nozzle inspection method for a liquid ejection apparatus comprising: a second electrode provided at a position that can face the first electrode;
Based on an electrical change between the two electrodes when liquid is ejected from the nozzle toward the second electrode with the first electrode and the second electrode facing each other and a voltage applied between the two electrodes. Before performing a discharge inspection for determining whether or not the liquid is discharged from the nozzle, a pre-inspection discharge process is performed to discharge a large amount of liquid from the nozzle to the second electrode as compared to the time of the discharge inspection.
Is.

  In this nozzle inspection method, the first electrode and the second electrode are opposed to each other, and an electric change between the two electrodes is caused when liquid is ejected from the nozzle toward the second electrode with a voltage applied between the two electrodes. Based on this, a discharge inspection is performed to determine whether or not liquid is discharged from the nozzle. Before the discharge inspection, a pre-inspection discharge process is performed in which a larger amount of liquid is discharged from the nozzle to the second electrode than in the discharge inspection. In this way, when there is foreign matter on the second electrode, the foreign matter can be removed by the liquid ejected before the ejection test, or the distance between the first electrode and the foreign matter can be increased. Therefore, it is possible to suppress noise caused by foreign matter in the discharge inspection. In this nozzle inspection method, various aspects of the above-described liquid ejecting apparatus may be employed, and steps for realizing each function of the above-described liquid ejecting apparatus may be added.

  The program of the present invention is for causing one or more computers to implement the nozzle inspection method described above. This program may be recorded on a computer-readable recording medium (for example, hard disk, ROM, FD, CD, DVD, etc.) or from a computer via a transmission medium (communication network such as the Internet or LAN). It may be distributed to another computer, or may be exchanged in any other form. When this program is executed by a computer, the above-described nozzle inspection method of the present invention is realized, so that the same effect as the nozzle inspection method of the present invention can be obtained.

1 is a block diagram illustrating a configuration of an inkjet printer 10. FIG. FIG. 2 is a schematic cross-sectional view of the printer 10. FIG. 2 is a schematic plan view of the printer 10. FIG. 3 is an explanatory diagram showing an arrangement of a plurality of heads 62 in the head unit 60. Explanatory drawing which shows arrangement | positioning of the several nozzle formed in the 1st head 62a. Explanatory drawing which shows the mode of printing. An explanatory view showing the whole composition of inspection unit 70. FIG. The top view of the test | inspection electrode 72. FIG. Explanatory drawing which shows the drive signal COM and the detection signal corresponding to it. Explanatory drawing which shows an example of the determination result in a detection signal and a detection control part. A table when the nozzles of the first head 62a are divided into blocks. The flowchart of the integrated determination routine of a nozzle. Explanatory drawing of the data stored in the memory of the detection control part 76. FIG. The flowchart of a digital signal output routine. Explanatory drawing which shows an example of the data of the register for transmission of the detection control part. Explanatory drawing which shows an example of the result of integrated determination. The flowchart of the pre-inspection ejection process.

  Next, an embodiment embodying the present invention will be described. FIG. 1 is a block diagram illustrating a configuration of an ink jet type printer 10, FIG. 2 is a schematic cross-sectional view of the printer 10, and FIG. 3 is a schematic plan view of the printer 10.

  The printer 10 is communicably connected to the personal computer PC, inputs print data from the personal computer PC, and prints an image on a print medium S such as paper or cloth based on the print data. The printer 10 includes a controller 20 that executes various controls and outputs commands, and a unit group 30 that executes various processes while exchanging signals with the controller 20.

  The controller 20 includes a CPU 22 that controls the entire printer 10 and a unit control circuit 24 that controls each unit of the unit group 30. The CPU 22 executes various programs stored in the memory 28 based on detection signals input from various detectors provided in the unit group 30 and print data received from the personal computer PC via the interface unit 26. Each unit is controlled via the unit control circuit 24 while temporarily storing data in 28. The unit group 30 includes a transport unit 40 that transports the print medium S, a moving unit 50 that moves the head unit 60, a head unit 60 that drives the head 62 so that ink is ejected from the nozzles, and nozzles formed on the head 62. An inspection unit 70 that performs inspection is included. 2 and 3, the transport unit 40 transports the roll-shaped print medium S from the upstream side in the transport direction (X direction) to the downstream side by the motor-driven upstream roller 42 and the downstream roller 44. Then, it is wound up by the winding mechanism 46. The print medium S is vacuum-sucked from the lower side of the platen 48 in the printing area between the rollers 42 and 44. Thereby, the position of the printing medium S during printing is fixed. As shown in FIGS. 2 and 3, the moving unit 50 freely moves the head unit 60 in the transport direction (X direction) of the print medium S and the width direction (Y direction) of the print medium S. The moving unit 50 moves the head unit 60 in the X direction by the X-axis stage 52, and moves the head unit 60 together with the X-axis stage 52 in the Y direction by the Y-axis stage 54. As shown in FIG. 3, the head unit 60 includes a head 62 having a plurality of nozzles, and ejects ink from the nozzles toward the print medium S by a drive signal from the controller 20. The head unit 60 includes a plurality of heads 62 as will be described later. Each head 62 ejects ink by pressure using a piezo element. The inspection unit 70 is for inspecting whether or not the nozzle is clogged. As shown in FIG. 3, the inspection unit 70 includes an inspection electrode 72 at a position that can face the head 62 of the head unit 60. Details of the inspection unit 70 will be described later.

  The head unit 60 will be described in more detail. FIG. 4 is an explanatory diagram showing the arrangement of the plurality of heads 62 in the head unit 60. In the drawing, the arrangement of the head 62 is shown as seen through the top surface of the printer 10. As shown in FIG. 4, the head unit 60 has 15 heads 62. The fifteen heads 62 are arranged in a zigzag along the Y direction. For convenience of explanation, the first head 62a, the second head 62b,..., The fourteenth head 62n, and the fifteenth head 62o are referred to from the upper end side to the lower end side in the Y direction. For this reason, the odd-numbered heads 62a, 62c, 62e... Form a straight line so as to be parallel to the Y direction, and the even-numbered heads 62b, 62d, 62f. Make a straight line so that

  FIG. 5 is an explanatory diagram showing the arrangement of a plurality of nozzles formed in the first head 62a. In the drawing, the nozzle arrangement is shown as seen through the top surface of the first head 62a. Further, the second head 62b to the fifteenth head 62o have the same configuration as the first head 62a. The first head 62a has a nozzle row of eight colors. Specifically, in order from the left side of FIG. 5, the Mk row for ejecting mat black ink, the Gr row for ejecting green ink, the Or row for ejecting orange ink, the Cl row for ejecting clear ink, and the photo black ink are ejected. Pk column, Cy column that discharges cyan ink, Ma column that discharges magenta ink, and Ye column that discharges yellow ink. Each nozzle row has 180 nozzles. The 180 nozzles are arranged at a constant nozzle pitch (1/180 inch) along the Y direction. For convenience of explanation, they are referred to as # 1, # 2,..., # 180 in order from the nozzle on the upper end side in the Y direction. Looking at each nozzle row of the first head 62b and each nozzle row of the second head 62b, the Y coordinate position of each of the four nozzles on the lower end side in the Y direction of the first head 62a is Y of the second head 62b. The Y coordinate positions of the four nozzles on the upper end side in the direction coincide with each other. Thus, two nozzles having the same Y coordinate position can form dots while interpolating each other. This relationship is the same between the α-th head and the (α + 1) -th head (α is an integer from 1 to 14).

  The procedure for printing on the print medium S using such a head unit 60 will be outlined below. 2 and 3, the controller 20 controls the transport unit 40 so that a new surface of the print medium S is supplied to the print area, and also controls the moving unit 50 so that the head unit 60 is at the initial position. To do. The initial position is the most upstream position in the X direction and the most extreme position in the Y direction in the print area. The head unit 60 arranged at the initial position is indicated by a solid line in FIGS. At the same time, the controller 20 controls the moving unit 50 so that the head unit 60 moves from the most upstream position in the X direction of the printing region to the most downstream position (indicated by a one-dot chain line in FIGS. 2 and 3). By controlling the head unit 60 so that ink is ejected from the nozzles of the moving head 62, dot rows arranged in the X direction are formed. This operation is referred to as one pass. After forming a dot row for one pass in this way, the controller 20 controls the moving unit 50 so that the head unit 60 moves to the lower end side in the Y direction, and executes the next one pass again to execute the dot row in the X direction. Form. An example of the head unit 60 moved to the lower end side in the Y direction is indicated by a two-dot chain line in FIG. Then, when the operation of the number of passes determined according to the width direction of the print medium S is completed, the image of the print area of the print medium S is completed. FIG. 6 is an explanatory diagram showing a state of printing. FIG. 6 illustrates a nozzle row in which five nozzles are arranged in a row parallel to the Y direction for convenience of explanation. FIG. 6 shows a state in which dot rows in the X direction for a total of four passes from pass 1 to pass 4 are sequentially formed.

  The inspection unit 70 will be described in detail below. The inspection unit 70 includes an inspection circuit 71. The inspection circuit 71 is basically formed at a rate of one for each of the two heads 62. In the present embodiment, the number of heads is fifteen, and thus eight inspection circuits 71 are formed corresponding thereto. . For convenience of explanation, the eight inspection circuits 71 are referred to as a first inspection circuit 71A, a second inspection circuit 71B,. FIG. 7 is an explanatory diagram showing the configuration of one of the inspection circuits 71 of the inspection unit 71. The inspection circuit 71 applies a voltage between a metal-made flat inspection electrode 72 that receives ink ejected from nozzles formed on the head 62, and the inspection electrode 72 and the nozzle plate 63 of the head 62. A high-voltage power supply 74; and a detection control unit 76 that determines the magnitude of the signal based on a voltage signal when ink is ejected from the nozzle in a state where a voltage is applied between the inspection electrode 72 and the nozzle plate 63. ing. The nozzle plate 63 is a plate on which a plurality of nozzles are formed, and also functions as a part of the inspection unit 70. An area of the nozzle plate 63 that faces the inspection electrode 72 when performing a nozzle inspection described later is referred to as a head-side inspection area 81, and of the inspection electrode 72 that faces the nozzle plate 63 when performing a nozzle inspection described later. The region is referred to as an electrode side inspection region 82. In the present embodiment, the head side inspection region 81 is the entire surface (the lower surface in FIG. 7) on the inspection electrode 72 side of the nozzle plate 63. On the other hand, the electrode-side inspection region 82 is a predetermined partial region of the surface of the inspection electrode 72 on the nozzle plate 63 side (the upper surface in FIG. 7).

  As described above, since the inspection circuit 71 is basically formed at a ratio of one to the two heads 62, the inspection electrode 72 is basically formed at a ratio of one to the two heads 62. One inspection electrode 72 has two electrode-side inspection regions 82. FIG. 8 shows a plan view of the inspection electrode 72. In this embodiment, since the number of heads is 15, eight inspection electrodes 72 are formed correspondingly, and there are 15 electrode-side inspection regions 82. For convenience of explanation, the eight inspection electrodes 72 are referred to as a first inspection electrode 72A, a second inspection electrode 72B,..., And the fifteen electrode-side inspection regions 82 are referred to as a first electrode-side inspection region 82a and a second electrode-side inspection. The regions 82b,. Specifically, as shown in FIG. 8, the first inspection electrode has a first electrode side inspection region 82a and a third electrode side inspection region 82c, and the second inspection electrode 72B has a fifth electrode side inspection region 82e. And the seventh electrode side inspection region 82g, the third inspection electrode 72C has the ninth electrode side inspection region 82i and the eleventh electrode side inspection region 82k, and the fourth inspection electrode 72D has the thirteenth electrode side inspection region 82g. The fifth inspection electrode 72E has a second electrode side inspection region 82b and a fourth electrode side inspection region 82d, and the sixth inspection electrode 72F has a sixth electrode. Side inspection region 82f and eighth electrode side inspection region 82h, seventh inspection electrode 72G has tenth electrode side inspection region 82j and twelfth electrode side inspection region 82l, and eighth inspection electrode 72H It has a 14-electrode inspection region 82n. The first to fifteenth electrode-side inspection regions 82a to 82o have a one-to-one correspondence with the first to fifteenth heads 62a to 62o (see FIG. 4). That is, the first to fifteenth electrode side inspection regions 82a to 82o are head side inspection regions 81 (first head side inspection regions 81a to 81a) of fifteen nozzle plates 63 (referred to as first to fifteenth nozzle plates 63a to 63o). 15th head side inspection area 81o). In the present embodiment, since the number of heads 62 is 15, the fourteenth head 62n has one electrode-side inspection region 82n and corresponds to one head 62n (head-side inspection region 81n). Yes. As shown in FIG. 3, such an inspection electrode 72 is provided at a position off the left side (upstream side in the X direction) from the printing region. FIG. 7 shows the configuration of the electric circuit for one inspection electrode 72, but such an electric circuit is assembled for each of the first to eighth inspection electrodes 72A to 72H.

  The high-voltage power source 74 is a power source for setting the inspection electrode 72 to a predetermined potential, and is constituted by a DC power source of 600 to 1000 V here. A first limiting resistor 73 and a second limiting resistor 75 are disposed between the high voltage power supply 74 and the inspection electrode 72. These limiting resistors 73 and 75 control the current flowing between the high-voltage power supply 74 and the inspection electrode 72, and here the resistance values of both are set to 1.6 MΩ.

  The detection control unit 76 controls voltage application between the inspection electrode 72 and the nozzle plate 63 by the high voltage power source 74. Further, the detection control unit 76 determines whether or not the inspection target nozzle ejects ink based on the voltage signal (analog signal) of the inspection electrode 72 amplified by the amplifier 77, and the controller 20 uses the determination result as a digital signal. Send to. Between the amplifier 77 and the inspection electrode 72, an inspection capacitor 78 for removing a bias component (DC component) of the inspection electrode 72 is disposed. One end of a smoothing capacitor 79 is connected between the first limiting resistor 73 and the second limiting resistor 75. The other end of the smoothing capacitor 79 is grounded. The smoothing capacitor 79 suppresses a rapid change in potential. Here, the capacity of the inspection capacitor 78 is 4700 pF, the amplification factor of the amplifier 77 is 4000 times, and the capacity of the smoothing capacitor 79 is 0.1 μF.

  Next, the operation of the printer 10 of this embodiment, particularly the operation when inspecting the nozzles will be described. In the inspection of the nozzle to be inspected, the controller 20 performs a discharge inspection for checking whether ink can be discharged satisfactorily, and a noise inspection for checking whether noise that affects the determination result has occurred during the discharge inspection. carry out.

  First, the discharge inspection will be described. FIG. 9 is an explanatory diagram showing the drive signal COM and the detection signal corresponding to the drive signal COM. FIG. 9A shows the waveform of the drive signal COM, and FIG. 9B shows the waveform of the detection signal output from the amplifier 77. The controller 20 outputs a drive signal COM for driving the piezo element shown in FIG. 9A to each head 62 with the voltage of the high voltage power supply 74 applied between the nozzle plate 63 and the inspection electrode 72. The drive signal COM is a combination of a pulse output section for outputting 20 to 30 ink ejection pulses and a pause section of a constant potential (intermediate potential). When such a drive signal COM is applied to a piezo element, 20 to 30 ink droplets are ejected from the nozzle corresponding to the piezo element. Then, in response to this, a detection signal (analog signal, see FIG. 9B) is output from the amplifier 77 to the detection control unit 76. The detection control unit 76 detects the amplitude Va of the detection signal corresponding to the drive signal COM (difference between the highest potential VH and the lowest potential VL of the detection signal), and detects the detected amplitude Va and a predetermined threshold Vth (for example, 3V). If the amplitude Va of the detection signal is larger than the threshold value Vth, the detection control unit 76 generates a digital signal indicating “large amplitude” (good ejection). Conversely, if the amplitude Va of the detection signal is smaller than the threshold value Vth, a digital signal representing “small amplitude” (ejection failure) is generated.

  Here, the principle of the discharge inspection will be described. In FIG. 7, the head unit is configured such that ink is ejected from the inspection target nozzle in a state where the head side inspection region 81 and the electrode side inspection region 82 are opposed to each other and a voltage is applied between the nozzle plate 63 and the inspection electrode 72. 60, when the ink is actually ejected from the nozzle, the voltage signal of the inspection electrode 72 changes greatly. When the ink is not ejected from the nozzle, the voltage signal of the inspection electrode 72 is almost the same. It does not change. Therefore, it is possible to determine whether or not the inspection target nozzle has ejected ink based on the change in the voltage signal. Although this principle has not been clarified accurately, it is thought as follows. In general, it is known that when the distance between a pair of electrode plates constituting a capacitor changes, the charge stored in the capacitor changes. When ink is ejected from the ground potential nozzle plate 63 toward the high potential inspection electrode 72, the distance d (see FIG. 6) between the ink droplet of the ground potential and the inspection electrode 72 changes, and a pair of electrodes of the capacitor As when the distance between the plates changes, the charge stored in the inspection electrode 72 changes. As a result, the charge is transferred to the inspection electrode 72, and the inspection capacitor 78 and the amplifier 77 detect the voltage that changes accordingly, and the detection signal is output to the detection control unit 76.

  Next, noise inspection will be described. During the noise inspection period, the controller 20 makes the head-side inspection region 81 and the electrode-side inspection region 82 face each other, and selects which nozzle in the state where the voltage of the high-voltage power supply 74 is applied between the nozzle plate 63 and the inspection electrode 72. The drive signal COM is not given to the piezo elements. That is, the noise inspection period is a non-ejection period in which ink droplets are not ejected. Even during this period, the detection signal (analog signal) is output from the amplifier 77 to the detection control unit 76. The detection control unit 76 compares the amplitude Va of the detection signal with the threshold value Vth, and if the amplitude Va of the detection signal is larger than the threshold value Vth, a digital signal indicating “large amplitude” (with noise) is transmitted to the controller 20. To do. Conversely, if the amplitude Va of the detection signal is smaller than the threshold value Vth, a digital signal representing “small amplitude” (no noise) is transmitted to the controller 20. In FIG. 7, in the state where a voltage is applied between the nozzle plate 63 and the inspection electrode 72, when the drive signal COM is not applied to the piezo element of any nozzle, the voltage signal of the inspection electrode 72 is hardly changed. However, when noise occurs in the inspection electrode 72, the voltage signal of the inspection electrode 72 greatly changes due to the noise. For this reason, the presence or absence of noise can be determined based on the change in the voltage signal. Such noise is often caused by foreign matters such as dust adhering to the head-side inspection area 81 and the electrode-side inspection area 82. This is because the foreign matter existing in the opposed region of the nozzle plate 63 to which the voltage is applied and the inspection electrode 72 is likely to cause noise. Further, when a foreign object adheres to one of the nozzle plate 63 and the inspection electrode 72, noise is more likely to occur as the distance between the other and the foreign object is shorter.

  Specific examples of discharge inspection and noise inspection will be described. Here, a case where the ejection inspection is performed twice for one nozzle and then the noise inspection is performed once will be described as an example. An example of the detection signal output from the amplifier 77 at that time and the determination result in the detection control unit 76 is shown in FIG. In FIG. 10A, since the amplitude Va of the detection signal exceeds the threshold value Vth in both ejection inspections, the detection control unit 76 generates both “large amplitude” digital signals, and in the subsequent noise inspection. Since the amplitude Va is equal to or less than the threshold value Vth, a “small amplitude” digital signal is generated. When these three digital signals are combined and determined, the nozzle is determined as “normal”. In FIG. 10B, since the amplitude Va of the detection signal is less than or equal to the threshold value Vth in the two ejection inspections, the detection control unit 76 generates both “small amplitude” digital signals, and the amplitude Va in the subsequent noise inspection. Is less than the threshold value Vth, a “small amplitude” digital signal is generated. When these three digital signals are integrated and determined, the nozzle is determined to be “abnormal”. In the detection signal of FIG. 10C, since the amplitude Va of the detection signal exceeds the threshold value Vth in the first ejection test, the detection control unit 76 generates a “large amplitude” digital signal, and in the second ejection test. Since the amplitude Va is equal to or smaller than the threshold value Vth, a “small amplitude” digital signal is generated. In the subsequent noise inspection, a digital signal having “small amplitude” is generated because the amplitude Va is equal to or smaller than the threshold value Vth. When these three digital signals are integrated and determined, the nozzle is determined to be “abnormal”. That is, if one of the plurality of ejection inspections is “small in amplitude” even once, the nozzle may be clogged, so that it is determined as “abnormal”. In FIG. 10D, since the amplitude Va of the detection signal exceeds the threshold value Vth in both of the ejection inspections, the detection control unit 76 generates both “large amplitude” digital signals, and also in the subsequent noise inspection. Since the amplitude Va exceeds the threshold value Vth, a “large amplitude” digital signal is generated. When these three digital signals are integrated and determined, the nozzle is determined as “unknown”. The fact that the amplitude Va exceeds the threshold value Vth in the noise inspection is highly likely that noise has been mixed in the previous ejection inspection, and the amplitude Va may have exceeded the threshold value Vth due to the noise. Whether it is normal or abnormal cannot be determined, and it is determined as “unknown”. In this way, when the noise test result is “large amplitude”, it is highly possible that the immediately preceding discharge test is affected by noise. Is determined.

  Next, a nozzle integration determination routine executed by the controller 20 and a digital signal output routine executed by the detection control unit 76 of the inspection unit 70 will be described. Here, nozzles are processed in units of blocks. For this reason, prior to the description of each routine, how to divide the blocks will be described. For each head 62, the block divides a plurality of nozzles of the head 62 so that 15 nozzles form one block. FIG. 11 is a table showing a state when 1440 (180 × 8 columns) nozzles of the first head 62a are divided into blocks. Specifically, in the Mk column, # 1 to # 15 are first blocks, # 16 to # 30 are second blocks, and so on, and then the Gr column, Or column, Cl column, Block division is performed in the same order in the order of Pk column, Cy column, Ma column, and Ye column. The second to fifteenth heads 62b to 62o are also divided into blocks in the same manner as in FIG.

  The nozzle integration determination routine will be described with reference to the flowchart of FIG. The controller 20 starts this integration determination routine every time the execution timing of the integration determination arrives. When this routine is started, the controller 20 first controls the moving unit 50 to move the head unit 60 so that each head 62 of the head unit 60 faces each inspection electrode 72 (step S100). Thereby, each head 62 and each test electrode 72 have the positional relationship shown in FIG. Next, one of the heads 62 facing each test electrode 72 is set as a test target head for each test electrode 72 (step S105). In addition, the process after step S105 in an integrated determination routine is performed independently about each of eight test | inspection circuits 71A-H. Further, in the present embodiment, when there are a plurality of heads 62 facing each inspection electrode 72, the head 62 positioned on the upper side in FIG. 8 is set as the inspection target head first. Therefore, for example, when the processing after step S105 is performed for the first inspection circuit 71A, the first head 62a is first set as the inspection target head in step S105, and the processing after step S105 is performed for the second inspection circuit 71B. In step S105, first, the fifth head 62e is set as an inspection target head. The same applies to the other inspection circuits 71. Since the eighth inspection circuit 71H faces only the fourteenth head 62n, the fourteenth head 62n is set as the inspection target head in step S105.

  Subsequently, a value 1 is set to the variable p representing the block number (step S110), the p-th block is set as the inspection target block (step S120), and the inspection target block is inspected (step S130). Specifically, the controller 20 sequentially sets 15 nozzles belonging to the p-th block of the inspection target head as inspection target nozzles, and supplies the drive signal COM shown in FIG. 9A to the piezo element of the inspection target nozzle. Is continuously applied twice, and thereafter, the drive signal COM is not applied for a predetermined period. As a result, the nozzle to be inspected is subjected to two ejection inspections and one noise inspection. The detection control unit 76 of the inspection unit 70 detects two discharge inspection detection signals output from the amplifier 77 and one noise inspection detection while a voltage is applied between the inspection electrode 72 and the nozzle plate 63. The signal is acquired and stored in a temporary storage area (not shown) of the detection control unit 76. Then, after temporarily storing each of the three detection signals for all 15 nozzles belonging to the p-th block, the detection control unit 76 executes a digital signal output routine. FIG. 13 shows data stored in the temporary storage area of the detection control unit 76 at this time. The first to third data are detection signals for the discharge inspection (first time), discharge inspection (second time), and noise inspection for the smallest nozzle (# 1 or # 2) belonging to the p-th block. Yes, the 4th to 6th data are detection signals for the discharge inspection (first time), discharge inspection (second time), and noise inspection for the nozzle having the second smallest number among the nozzles belonging to the p-th block. Since the meanings of the subsequent data are the same, the description thereof is omitted.

  Here, a digital signal output routine executed by the detection control unit 76 will be described with reference to the flowchart of FIG. This routine is started when detection of detection signals of all the nozzles included in the p-th block is completed, that is, when all 1 to 45 pieces of data are stored in the temporary storage area shown in FIG. When this routine is started, the detection control unit 76 first sets a value 1 to the variable k (step S310). Subsequently, the kth data is read from the temporary storage area of the detection control unit 76 (step S320), and it is determined whether the data, that is, the amplitude Va of the detection signal exceeds the threshold value Vth (step S330). If the amplitude Va exceeds the threshold value Vth, a digital signal indicating “large amplitude” is written in a kth position of a transmission register (not shown) of the detection control unit 76 (step S340). On the other hand, if the amplitude Va is equal to or less than the threshold value Vth, a digital signal indicating “small amplitude” is written in the kth position of the transmission register of the detection control unit 76 (step S350). Then, after the writing to the transmission register is completed in step S340 or step S350, the variable k has reached the upper limit value (here, the upper limit value is 45 because the number of nozzles included in one block is 15). (Step S360), and if the variable k has not reached the upper limit, the variable k is incremented by 1 (step S370), and the process returns to step S320 again. On the other hand, if the variable k has reached the upper limit value, the contents of the transmission register are transmitted to the controller 20 (step S380), and this routine is terminated. That is, after the digital signal (45 digital signals) corresponding to the full capacity of the transmission register is stored, the detection control unit 76 transmits the contents of the transmission register to the controller 20. The data in the transmission register at this time is shown in FIG.

  Returning to FIG. 12, the controller 20 determines whether or not one block of digital signals (45 digital signals) has been acquired from the detection control unit 76 (step S140). If not, the process returns to step S140. Return. On the other hand, if a digital signal for one block is acquired from the detection control unit 76, the integration determination is performed, and the nozzles are associated with the integration determination result (step S150). For example, when the block to be inspected is the first block, the first to third digital signals out of 45 digital signals are the ejection inspection (first time) and the ejection inspection (second time) of the # 1 nozzle in the Mk row. The 4th to 6th digital signals represent the results of the ejection test (first time), the ejection test (second time), and the noise test of the nozzle # 2 in the Mk column. Identify which nozzle the digital signal corresponds to. At the same time, for the specified nozzle, three digital signals corresponding thereto are integrated and determined to be normal or abnormal. It should be noted that the determination of normal or abnormal (integrated determination) is as already described with reference to FIG. After performing the integrated determination in this way, the integrated determination result is associated with the identified nozzle. An example is shown in FIG. 16A shows a digital signal from the inspection control unit 76, and FIG. 16B shows a result of the integrated determination for each nozzle.

  Subsequently, the controller 20 determines whether or not there is an “unknown” result as a result of the integration determination of 15 nozzles included in the p-th block (step S160). If there is an "unknown" item in step S160, it is determined whether or not the flag F is 1 (step S170). Here, the flag F is set to a value 1 when the pre-inspection ejection process described later has already been performed, and the initial value is set to a value 0. When the flag F is 0, the pre-inspection ejection process is executed (step S180). Here, the pre-inspection ejection process is a process for removing the cause of noise when there is an unknown nozzle and a correct ejection inspection result cannot be obtained. Hereinafter, the description of the integrated determination routine will be interrupted, and the pre-inspection ejection process will be described with reference to the flowchart of FIG. In this pre-inspection ejection process, no voltage is applied between the inspection electrode 72 (first to eighth inspection electrodes 72A to 72H) and the nozzle plate 63 (first to fifteenth nozzle plates 63a to 63o). Do.

  When the pre-inspection ejection process is started, the controller 20 first stops the integration determination routine (step S400). As described above, the processing after step S105 in the integrated determination routine is executed independently for each of the eight inspection circuits 71A to 71H. Therefore, not only the integrated determination routine using the inspection circuit 71 that executes the pre-inspection ejection process this time (the inspection circuit 71 determined to be positive in step S160), but also the integrated determination routine using the other inspection circuits 71 is stopped. It is. This is because the process of moving the head unit 60 is performed in the process described later.

  Subsequently, the controller 20 moves the head unit 60 and ejects ink from the head 62, so that the inspection electrode 72 facing the head 62 determined to have an unknown nozzle has ink throughout the electrode-side inspection region 82. The head unit 60 and the moving unit 50 are controlled so as to be distributed (step S410). For example, when the pre-inspection ejection process is performed by making a positive determination in step S160 when the integrated determination routine is executed using the inspection circuit 71A with the first head 62a as the inspection target head, the head unit 60 is used. Then, the movement unit 50 is controlled to repeat the movement of the first head 62a and the ejection of ink from the eight-color nozzle rows of the first head 62a, and the ejected ink spreads over the entire first electrode side inspection region 82a. Like that. In order to spread the ink over the entire first electrode side inspection region 82a, for example, once the ink is discharged to the first electrode side inspection region 82a at an interval smaller than the interval between the nozzles in the X and Y directions of the head 62a. The head unit 60 may be moved and the ink ejected a plurality of times, for example, the head unit 60 is further moved so as to fill the space between the ink ejected from the nozzles, and the ink is ejected again. The ink discharge amount per nozzle in step S410 is the ink discharge amount in one discharge inspection of one nozzle (the amount of ink of 20 to 30 droplets discharged by the drive signal COM in FIG. 9). ) In advance. For this reason, the ink discharge amount (total discharge amount) in the pre-inspection discharge process is larger than the ink discharge amount in one discharge inspection of one nozzle. In this way, by allowing the ink to spread over the entire electrode side inspection region 82, the foreign matter in the electrode side inspection region 82 is removed by this ink or the distance between the nozzle plate 63 and the foreign matter is increased, and the foreign matter is removed. It is possible to suppress the occurrence of noise.

  When ink is ejected to the electrode-side inspection area 82, the integrated determination routine that was stopped in step S400 is resumed (step S420), and the pre-inspection ejection process is terminated. Thereby, all the integrated determination routines using each inspection circuit 71 are restarted.

  Returning to the description of the integrated determination routine of FIG. When the pre-inspection ejection process in step S180 is performed, the controller 20 sets the flag F to a value of 1 (step S190), sets the current p-th block as the inspection target block again (step S200), and proceeds to step S130. Return. As a result, re-inspection is performed in units of blocks.

  If there are no unknown nozzles in the initial inspection or if there are no unknown nozzles due to re-inspection, a negative determination is made in step S160 to initialize the flag F to a value of 0 (step S215). Correspondences between the 15 identified nozzles and their integrated determination results are determined and stored in the memory 28 (step S220). Thereafter, it is determined whether or not the variable p has reached the upper limit value (here, the total number of blocks) (step S230). If the variable p has not reached the upper limit value, the variable p is incremented by 1 (step S240). The process returns to step S120 again. As a result, the next block is inspected.

  If the variable p has reached the upper limit value in step S230, it is determined whether there is an uninspected head 62 that faces the inspection electrode 72 (step S250). For example, regarding the first inspection circuit 71A, when the nozzle inspection is performed by setting the first head 62a as the inspection target head in the above-described step S105, the third head 62c facing the first inspection electrode 72A is not inspected. Therefore, a positive determination is made in step S250. If a positive determination is made, an uninspected head is set as the next inspection target head (step S260), and the process returns to step S110. As a result, nozzle inspection is performed for an uninspected head. When there is no uninspected head facing the inspection electrode 72, an affirmative determination is made in step S250, and this routine is terminated.

  On the other hand, even if the pre-inspection ejection process is performed in step S180 and the re-inspection is performed, if there is an unknown nozzle again, an affirmative determination is made in steps S160 and S170, and the pre-inspection ejection process performs noise. An error message notifying that the nozzle inspection cannot be completed without being generated is output (step S210), and this routine is terminated. The message may be output by displaying it on a display (not shown) or by outputting sound.

  As described above, when performing nozzle inspection, when there is an unknown nozzle, that is, when noise is generated, re-inspection is performed after performing pre-inspection ejection processing, thereby suppressing noise caused by foreign matter and re-inspecting. The generation of unknown nozzles in the inspection is suppressed.

  Here, the correspondence between the components of the present embodiment and the components of the present invention will be clarified. The head 62 of this embodiment corresponds to the head of the present invention, the nozzle plate 63 corresponds to the first electrode, the inspection electrode 72 corresponds to the second electrode, and the inspection unit 70 corresponds to the discharge inspection means and the foreign matter detection means. The controller 20 corresponds to the processing means, and the moving unit 50 corresponds to the moving means. In the present embodiment, an example of the nozzle inspection method of the present invention is also clarified by describing the operation of the printer 10.

  According to the printer 10 of the present embodiment described above, the pre-inspection ejection process for ejecting a large amount of ink from the nozzles to the inspection electrode 72 is performed before the ejection inspection, as compared with the single ejection inspection of one nozzle. Accordingly, the foreign matter on the inspection electrode 72 can be removed by the ink ejected in the pre-inspection ejection process, or the distance between the nozzle plate 63 and the foreign matter can be increased, and noise caused by the foreign matter in the ejection inspection can be suppressed. Can do. Further, the pre-inspection ejection process is performed without applying a voltage between the inspection electrode 72 (first to eighth inspection electrodes 72A to 72H) and the nozzle plate 63 (first to fifteenth nozzle plates 63a to 63o). The ink ejected in the pre-inspection ejection process is less likely to have a charge, and it is possible to suppress the occurrence of a mist having a charge from the ejected ink, for example, adhering to the surroundings of the nozzle plate 63 and the like to contaminate it. In addition, in the pre-inspection ejection process, ink is ejected from the nozzles into the electrode-side inspection area 82 where foreign matter is likely to cause noise, and therefore noise due to foreign matter in the ejection inspection can be easily suppressed. Further, in the pre-inspection ejection process, the ink is spread over the entire electrode-side inspection region 82, so that the foreign matter is removed or the inspection electrode 72 and the foreign matter are removed regardless of where the foreign matter is in the electrode-side inspection region 82. Can be separated. Furthermore, since the pre-inspection ejection process is performed when the presence / absence of noise is determined based on an electrical change during the noise inspection period and a positive determination is made (when there is an unknown nozzle), the presence / absence of noise is used. Noise caused by foreign matter in the discharge inspection can be efficiently suppressed.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the above-described embodiment, ink is ejected from the 8-color nozzle row of the head 62 to the electrode-side inspection region 82 in the pre-inspection ejection process. Ink may be ejected from nozzles of some colors. Moreover, it is good also as what discharges an ink from the one part nozzle of a nozzle row. Furthermore, it is also possible to eject ink excluding the ink that is most difficult to dry out of a plurality of types of ink. For example, among the eight colors of ink according to the present embodiment, the matte black ink is most difficult to dry compared to the other seven colors of ink, and therefore, the ink may be ejected from nozzles of seven colors other than the matte black. As described above, if ink other than the ink that is most difficult to dry is ejected, it is possible to prevent foreign matter from adhering to the ink ejected in the pre-inspection ejection process and causing noise. Further, it is sufficient to eject ink except the ink that is most difficult to dry. For example, one of seven colors other than mat black may be ejected, or two or more colors may be ejected. Good. Of the seven colors of ink other than matte black, only one color of ink that is most likely to dry may be ejected.

  In the embodiment described above, pre-inspection ejection is performed without applying a voltage between the inspection electrode 72 (first to eighth inspection electrodes 72A to 72H) and the nozzle plate 63 (first to fifteenth nozzle plates 63a to 63o). The nozzle plate 63 other than the nozzle plate 63 of the head 62 that discharges ink in the pre-inspection discharge process, and the test electrodes 72 other than the test electrode 72 that is the ink discharge destination in the pre-inspection discharge process are used. A voltage may be applied. For example, if ink is ejected from the first head 62a to the first inspection electrode 72A, a voltage is applied between the second to fifteenth nozzle plates 63b to 63o and the second to eighth inspection electrodes 72B to 72H. May be. Even in this case, similarly to the above-described embodiment, the ink ejected by the pre-inspection ejection process is less likely to have a charge, and the surroundings of the nozzle plate 63 and the like can be suppressed from being stained by the ink mist having the charge. The pre-inspection ejection process may be performed in a state where a voltage is applied between the nozzle plate 63 of the head 62 that ejects ink in the pre-inspection ejection process and the inspection electrode 72 that is the ink ejection destination in the pre-inspection ejection process. Good. However, it is preferable not to apply a voltage because an effect of suppressing the surrounding stains caused by the ink mist described above can be obtained.

  In the above-described embodiment, ink is ejected from the first head 62 a to the first electrode side inspection region 82 a in the pre-inspection ejection processing, but ink may be ejected from another head 62. Further, ink may be ejected from the plurality of heads 62.

  In the embodiment described above, the ink discharge amount per nozzle in the pre-inspection discharge process is the same as the ink discharge amount in a single discharge inspection of one nozzle, and the ink discharge amount (discharge) in the pre-inspection discharge process. The total amount) is set to be larger than the ink discharge amount in one discharge inspection of one nozzle, but the ink discharge amount in the pre-inspection discharge process is the ink discharge amount in one discharge inspection of one nozzle. If so, the discharge amount of the pre-inspection discharge process may be determined in any way. For example, when only one nozzle is used for the pre-inspection ejection process, the ink ejection amount from the one nozzle in the pre-inspection ejection process is larger than the ink ejection amount in one ejection inspection for one nozzle. What should I do. Further, when a plurality of nozzles are used for the pre-inspection ejection process, the ink ejection amount per nozzle in the pre-inspection ejection process may be smaller than the ink ejection amount in one ejection inspection of one nozzle. Good. Further, in the case where a plurality of ejection inspections are performed for one nozzle (in this embodiment, twice as shown in FIG. 10), the ink in the pre-inspection ejection process is larger than the ink ejection amount in the plurality of ejection inspections. The discharge amount may be increased. Furthermore, the inspection is more than the ink discharge amount (in this embodiment, the total amount of ink discharge by 180 nozzles × 8 nozzle rows × two discharge inspections) when performing the discharge inspection of all the nozzles of one head 62. The ink discharge amount in the pre-discharge process may be increased.

  In the above-described embodiment, the ink is discharged so that the ink spreads over the entire electrode-side inspection region 82 in the pre-inspection discharge process. However, any ink can be used as long as it discharges ink to the inspection electrode 72. The ink may be distributed to a part of the side inspection area 82. In addition, ink may be ejected to a region other than the electrode-side inspection region 82 in the inspection electrode 72. Even in this case, if noise is generated due to a foreign substance existing in a region other than the electrode-side inspection region 82, this can be suppressed. Further, if ink ejected to a region other than the electrode-side inspection region 82 flows into the electrode-side inspection region 82, noise caused by foreign matters in the electrode-side inspection region 82 can be suppressed. Ink discharge may be performed so that the ink reaches all of the inspection electrodes 72 in the pre-inspection discharge process.

  In the above-described embodiment, the head unit 60 is moved and the ink is ejected from the head 62 in the pre-inspection ejection process. However, the head unit 60 need not be moved. In this case, the ink discharge amount in the pre-inspection discharge process may be determined so that the ink flows over the inspection electrode 72 and reaches the entire electrode-side inspection region 82. Further, when the head unit 60 is not moved, it is not necessary to stop or restart the integrated determination routine in the pre-inspection ejection process. Therefore, for the head 62 and the inspection circuit 71 other than the head 62 and the inspection circuit 71 that perform the pre-inspection ejection process, the integrated determination routine may be continued even during the pre-inspection ejection process.

  In the above-described embodiment, when it is determined that there is noise in the noise inspection, that is, when there is an unknown nozzle, the pre-inspection ejection processing is performed. However, the pre-inspection ejection processing is any type if it is performed before the ejection inspection. The pre-inspection ejection process may be performed at the timing. For example, step S410 of the pre-inspection ejection process may be performed before the first step S130 of the integrated determination routine is executed. Alternatively, the pre-inspection ejection process may be executed every predetermined time, or the pre-inspection ejection process may be performed when an execution instruction is input from the user. Further, the pre-inspection ejection process is not limited to the case where there is an unknown nozzle, but the pre-inspection ejection process may be performed when it is detected that there is a foreign substance on the inspection electrode 72. For example, an inspection circuit includes a light emitting element that emits laser light and an incident light receiving element, and the inspection circuit detects whether or not the laser light is blocked by a foreign matter on the inspection electrode 72. The pre-inspection ejection process may be performed when an affirmative determination is made.

  In the above-described embodiment, two ejection inspections and one noise inspection are performed in the nozzle inspection of one nozzle. However, the ejection inspection may be performed only once or three or more times. It is good. Moreover, it is good also as what does not perform a noise test | inspection. In addition, the detection control unit 76 transmits the digital signal to the controller 20 after inspecting the nozzles in block units, but may transmit the digital signal to the controller 20 every time one nozzle is inspected. .

  In the above-described embodiment, the inspection electrode 72 is a flat metal, but is not limited to this as long as it can face the nozzle plate 63 and perform a discharge inspection based on an electrical change. . For example, it may be a mesh-like metal or a conductive sponge. Further, for example, the inspection electrode 72 may be provided in a moisturizing cap used for preventing drying of the nozzle or in a cleaning cap used for cleaning by sucking dust and ink in the nozzle.

  In the embodiment described above, the head-side inspection region 81 is the entire surface of the nozzle plate 63 on the inspection electrode 72 side (the lower surface in FIG. 7), and the electrode-side inspection region 82 is the surface of the inspection electrode 72 on the nozzle plate 63 side (see FIG. 7 is a predetermined partial region, but is not limited thereto. For example, the entire surface of the inspection electrode 72 and the entire surface of the nozzle plate 63 face each other during the nozzle inspection, and the electrode-side inspection region 82 may be the entire surface of the inspection electrode 72 on the nozzle plate 63 side. Further, since the entire surface of the inspection electrode 72 and a part of the nozzle plate 63 face each other at the time of nozzle inspection, the head-side inspection region 81 is a part of the surface on the inspection electrode 72 side of the nozzle plate 63 (the lower surface in FIG. 7). The electrode-side inspection region 82 may be the entire surface of the inspection electrode 72 on the nozzle plate 63 side. Further, as a configuration in which a part of the inspection electrode 72 and a part of the nozzle plate 63 face each other at the time of nozzle inspection, the head side inspection region 81 is a part of the surface on the inspection electrode 72 side of the nozzle plate 63, and the electrode side inspection region 82 may be a part of the surface of the inspection electrode 72 on the nozzle plate 63 side.

  In the above-described embodiment, each nozzle plate 63 is attached to each head 62. However, the present invention is not limited to this, and the nozzle plate 63 can come into contact with ink ejected from a nozzle to be inspected during ejection inspection. It only needs to be able to face the inspection electrode 72 at times. For example, the nozzle plate 63 and the head 62 may be moved separately, and the head 62 and the nozzle plate 63 may be in contact with each other as shown in FIG.

  In the embodiment described above, the moving unit 50 changes the positional relationship between the nozzle plate 63 and the inspection electrode 72 by moving the head unit 60, but the relative position between the nozzle plate 63 and the inspection electrode 72 is changed. It only needs to change the relationship. For example, the moving unit 50 may move the inspection electrode 72.

  In the embodiment described above, the nozzle plate 63 is set to the ground potential and the test electrode 72 is set to the high potential, and the voltage change of the test electrode 72 is detected. However, the nozzle plate 63 is set to the high potential and the test electrode 72 is set to the ground potential. The change in voltage may be detected.

  In the above-described embodiment, a method of ejecting ink by pressure using a piezo element is illustrated as an ink jet method. However, for example, a method of generating bubbles in a nozzle by heat may be employed.

  In the embodiment described above, an example in which the liquid ejection apparatus of the present invention is embodied in the ink jet printer 10 has been described. However, a liquid (dispersion) in which particles of liquid other than ink or functional material are dispersed, gel The present invention may be embodied in a fluid ejection device that ejects a fluid or the like, or may be embodied in a fluid ejection device that ejects a solid that can be ejected as a fluid. For example, a liquid ejecting apparatus that ejects a liquid in which a material such as an electrode material or a color material used for manufacturing a liquid crystal display, an EL (electroluminescence) display, and a surface emitting display is ejected, and a liquid material in which the material is dispersed is ejected. It is good also as a liquid discharge apparatus which discharges the liquid used as a liquid body discharge apparatus and a precision pipette as a sample. Also, transparent resin liquids such as UV curable resin to form liquid ejection devices that pinpoint lubricating oil to precision machines such as watches and cameras, micro hemispherical lenses (optical lenses) used for optical communication elements, etc. A liquid discharge device that discharges a liquid onto a substrate, a liquid discharge device that discharges an etching liquid such as acid or alkali to etch the substrate, a fluid discharge device that discharges gel, a powder that discharges powder such as toner A body discharge type recording apparatus may be used.

  10 printer, 20 controller, 22 CPU, 24 unit control circuit, 26 interface unit, 28 memory, 30 unit group, 40 transport unit, 42 upstream roller, 44 downstream roller, 46 take-up mechanism, 48 platen, 50 moving unit , 52 X-axis stage, 54 Y-axis stage, 60 head unit, 62 head, 62a to 62o 1st to 15th head, 63 nozzle plate, 63a to 63o 1st to 15th nozzle plate, 70 inspection unit, 71 inspection circuit , 71A to 71H 1st to 8th test circuit, 72 test electrodes, 72A to 72H 1st to 8th test electrodes, 73 1st limiting resistor, 74 high voltage power supply, 75 2nd limiting resistor, 76 detection control unit, 77 amplifier , 78 Inspection condenser, 79 Smoothing condenser Sir, 81 head side inspection area, 81a to 81o 1st to 15th head side inspection area, 82 electrode side inspection area, 82a to 82o 1st to 15th electrode side inspection area.

Claims (8)

A head having a plurality of nozzles for discharging liquid;
A first electrode in contact with the liquid;
A second electrode provided at a position capable of facing the first electrode;
Based on an electrical change between the two electrodes when liquid is ejected from the nozzle toward the second electrode in a state where the first electrode and the second electrode are opposed to each other and a voltage is applied between the two electrodes. Discharge inspection means for performing a discharge inspection for determining whether or not the liquid is discharged from the nozzle;
Processing means for performing a pre-inspection discharge process for discharging a large amount of liquid from the nozzle to the second electrode before the discharge inspection, compared to the time of the discharge inspection;
A liquid ejection device comprising: The processing means is means for performing the pre-inspection ejection processing in a state where no voltage is applied between the first electrode and the second electrode.
The liquid ejection device according to claim 1. The processing means is means for discharging liquid from the nozzle in a region of the second electrode facing the first electrode in the discharge inspection in the pre-inspection discharge processing.
The liquid ejection device according to claim 1 or 2. The head is capable of discharging a plurality of types of liquid from the nozzle,
The processing means is means for discharging a liquid excluding the liquid that is most difficult to dry out of the plurality of types of liquid from the nozzle to the second electrode in the pre-inspection discharge process.
The liquid ejection apparatus according to claim 1. The liquid ejection device according to any one of claims 1 to 4,
Moving means for relatively moving the head and the second electrode;
With
In the pre-inspection discharge process, the processing means causes the liquid to be discharged from the nozzle with movement by the moving means so that the liquid spreads over the entire region of the second electrode facing the first electrode in the discharge inspection. Is a means of discharging,
Liquid ejection device. The liquid ejection device according to any one of claims 1 to 5,
Foreign matter detection means for detecting the presence of foreign matter in the second electrode;
With
The processing means is means for performing the pre-inspection ejection processing when the foreign matter detection means detects that there is a foreign matter on the second electrode.
Liquid ejection device. A head having a plurality of nozzles for discharging liquid, a first electrode in contact with the liquid,
A nozzle inspection method for a liquid ejection apparatus comprising: a second electrode provided at a position that can face the first electrode;
Based on an electrical change between the two electrodes when liquid is ejected from the nozzle toward the second electrode with the first electrode and the second electrode facing each other and a voltage applied between the two electrodes. Before performing a discharge inspection for determining whether or not the liquid is discharged from the nozzle, a pre-inspection discharge process is performed to discharge a large amount of liquid from the nozzle to the second electrode as compared to the time of the discharge inspection.
Nozzle inspection method. A program that causes one or more computers to implement the nozzle inspection method according to claim 7.

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