JP2013146982A - Inspection device of liquid droplet ejection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To complete the inspection of an ejection mechanism in the liquid droplet ejection apparatus to make the droplet ejection of a plurality of volumes at the early stage.SOLUTION: There is provided an inspection device of a liquid droplet ejection apparatus that includes an ejection mechanism including a driving element to make the droplet ejected from a nozzle. The inspection device includes: an inspection voltage acquisition means to acquire the inspection voltage that shows an operating state of the driving element that makes the droplet ejected; a voltage determination means to determine whether the inspection voltage is abnormal by using different criterion when the driving element makes the droplet of a first volume ejected, and when the driving element makes the droplet of a second volume which is smaller than the first volume ejected; and an abnormal condition determination means that determines whether the ejection mechanism is abnormal when the inspection voltage is abnormal.

Description

  The present invention relates to an inspection apparatus for a droplet discharge device that discharges droplets for each discharge mechanism.

  In a printer that ejects ink droplets by driving a drive element for each of a plurality of ejection mechanisms, it is inspected whether or not ink droplets are normally ejected from nozzles (see Patent Document 1). . In Patent Document 1, a transistor (Patent Document 1, “Transistor 44”) in which ground-side electrodes of a plurality of drive elements are connected in common is provided, and ink droplets are ejected by a plurality of ejection mechanisms while the transistors are turned on. Discharge. On the other hand, the ejection mechanism is inspected one by one by driving the driving elements to be inspected one by one with the transistor turned off.

JP 2005-305992 A

However, the driving elements to be inspected must be driven one by one under the same driving conditions, and there is a problem that the driving elements cannot be inspected during a period during which an arbitrary print job is executed. That is, during a period during which an arbitrary print job is executed, the drive element can be driven under a plurality of drive conditions in order to eject a plurality of volumes of ink droplets. In addition, if an inspection is performed only when the drive element ejects a specific volume of ink droplets during a period during which an arbitrary print job is executed, there is a problem that the required period of the inspection becomes longer.
An object of the present invention has been made in view of the above problems, and an object of the present invention is to provide an inspection apparatus that can quickly complete the inspection of the ejection mechanism in a droplet ejection apparatus that ejects a plurality of volumes of droplets.

  In order to solve the above-described problems, the inspection apparatus of the present invention is provided in a droplet discharge device including a discharge mechanism including a drive element that discharges droplets from a nozzle. The inspection voltage acquisition unit acquires an inspection voltage indicating an operation state of the driving element that discharges the droplet. The voltage determination means uses a different determination condition for the inspection voltage when the driving element discharges a first volume of droplets and when the driving element discharges a second volume of droplets smaller than the first volume. It is determined whether or not is abnormal. The abnormality determination unit determines that the ejection mechanism is abnormal when the inspection voltage is abnormal.

  In the above-described configuration, the voltage determination means uses a different determination condition for the inspection voltage when the driving element discharges the first volume droplet and when the driving element discharges the second volume droplet. It is determined whether it is abnormal. The normal operating state of the drive element may differ between when the drive element ejects a first volume droplet and when the drive element ejects a second volume droplet. It can be determined whether or not the voltage is abnormal. The abnormality determination unit can determine whether or not the discharge mechanism is abnormal both in the case of discharging the first volume droplet and in the case of discharging the second volume droplet. Therefore, it is not necessary to wait for the opportunity for the discharge mechanism to discharge either the first volume or the second volume, and the abnormality determination unit can determine whether the discharge mechanism is abnormal at an early stage. Even when a plurality of droplets of a plurality of volumes can be ejected during execution of an arbitrary print job, the ejection mechanism inspection can be completed at an early stage.

  Here, when the driving element ejects the second volume droplet having a volume smaller than the first volume, the driving element is driven weaker than the case where the first volume droplet is ejected. Becomes smaller. Therefore, the inspection voltage acquisition means has a higher amplification factor of the amplification circuit when the driving element ejects the second volume of droplet than the amplification factor of the amplification circuit when the driving element ejects the first volume of droplet. You may enlarge it. Accordingly, it is possible to obtain an inspection voltage having an amplitude that can determine whether or not the drive element is abnormal even when the driving element ejects the droplet of the second volume.

  Further, the abnormality determination unit is configured to determine whether the discharge mechanism is abnormal by combining the first determination result when discharging the first volume droplet and the second determination result when discharging the second volume droplet. It may be determined whether or not. That is, whether or not the discharge mechanism is abnormal in consideration of both the first determination result and the second determination result when the first volume droplet and the second volume droplet are discharged. If it is determined, the inspection of the discharge mechanism can be completed at an early stage.

  Further, the abnormality determination unit may determine whether or not the ejection mechanism is abnormal by placing importance on the first determination result rather than the second determination result. When the driving element discharges the first volume droplet having a volume larger than the second volume, the driving element is driven more strongly than when the second volume droplet is discharged. The impact is reduced. Therefore, by placing importance on the first determination result rather than the second determination result, it can be accurately determined whether or not the ejection mechanism is abnormal.

It is a block diagram of a printer including an inspection device. (2A) is a schematic diagram of the ejection mechanism, and (2B) is a circuit diagram of the ejection head. (3A) is a diagram showing the nozzle, and (3B) is a timing chart showing the operation of the inspection switch. (4A) is a graph of an inspection voltage, and (4B) is a diagram showing an inspection table. It is a flowchart of an inspection process. It is a flowchart of an abnormality handling process. (7A) is a schematic diagram of the ejection mechanism of Modification 1, and (7B) is a circuit diagram of the ejection head of Modification 1. FIG. (8A) and (8B) are timing charts showing the operation of the inspection switch of the first modification. (9A) is a flowchart of the abnormality handling process of the first modification, and (9B) is a diagram showing an inspection table of the first modification.

Here, embodiments of the present invention will be described in the following order.
(1) First embodiment:
(1-1) Printer configuration:
(1-2) Inspection process:
(1-3) Abnormal response processing:
(2) Modification 1:
(3) Modification 2:
(4) Other variations:

(1) Printer configuration:
FIG. 1 is a block diagram showing a configuration of a printer 1 as a droplet discharge device including an inspection device according to an embodiment of the present invention. The printer 1 includes an ejection head 10 and a main substrate 20. The main board 20 includes a discharge availability data generation circuit 21 and a drive voltage generation circuit 22. The discharge enable / disable data generation circuit 21 is a circuit that generates discharge enable / disable data SI specifying whether or not to discharge ink droplets as droplets for each of a plurality of discharge mechanisms provided in the discharge head 10. The discharge propriety data generation circuit 21 outputs nozzle selection data obtained by serially combining the discharge propriety data SI to permutations of a plurality of discharge mechanisms to the discharge head 10. The discharge availability data generation circuit 21 generates discharge enable / disable data SI for each of a plurality of discharge timings, and outputs the discharge enable / disable data SI in the order of discharge timing. The ejection timing is a timing at which a plurality of ejection mechanisms provided in the ejection head 10 simultaneously eject ink droplets during a print job execution period. Further, the ejection propriety data generation circuit 21 generates a latch signal LAT and a switching signal CH and outputs them to the ejection head 10. The latch signal LAT is a timing signal for defining the ejection timing. The switching signal CH is a timing signal for defining a period in which the ejection timing is subdivided.

  The drive voltage generation circuit 22 is a circuit (drive voltage source) that generates a drive voltage COM for driving the piezo element 12 as a drive element included in the ejection head 10. The drive voltage generation circuit 22 includes a D / A conversion unit that generates a drive voltage COM based on digital data that defines a voltage pattern of the drive voltage, and an amplification unit that amplifies the D / A converted drive voltage COM. . The drive voltage COM output from the drive voltage generation circuit 22 is input to the application switch P of the ejection head 10.

  FIG. 2A is a schematic diagram illustrating a structure of a discharge mechanism provided in the discharge head 10, and FIG. 2B is a circuit diagram of a part of the discharge head 10. As shown in FIG. 1, the ejection head 10 includes a head IC 11, a piezo element 12, an ink chamber 13, a nozzle 14, and a diaphragm 15. The ejection head 10 includes a plurality of (not shown) ejection mechanisms, and each of the plurality of ejection mechanisms includes a piezo element 12, an ink chamber 13, a nozzle 14, and a diaphragm 15 as shown in FIG. 2A. In this embodiment, 90 ejection mechanisms are provided for each ink color of C (cyan), M (magenta), Y (yellow), and K (black), and a total of 360 (= N) ejection mechanisms are provided. ing. The piezo element 12 is a piezoelectric element. By applying the drive voltage COM to the piezo element 12, the piezo element 12 is mechanically distorted, and the diaphragm 15 constituting the wall surface of the ink chamber 13 filled with ink is vibrated. As a result, the pressure in the ink chamber is increased and decreased, and the ink in the ink chamber is ejected from the nozzle 14 as ink droplets. The application switch P is a switch that switches whether to apply the drive voltage COM to the piezo element 12 in each of the plurality of ejection mechanisms. That is, the application switch P selectively applies the drive voltage COM to the piezo elements 12 corresponding to the nozzles 14 designated when ink droplets are ejected by the ejectability data SI.

  As shown in FIG. 2B, in each of the plurality of ejection mechanisms (one-dot chain lines), the wiring for transmitting the drive voltage COM, the piezo element 12, the application switch P, and the ground are connected in series. The application switch P has a source-drain connected in series between the piezo element 12 and the ground. Accordingly, when the application switch P is turned on, the drive voltage COM is applied to the piezo element 12, and when the application switch P is turned off, the drive voltage COM is not applied to the piezo element 12. In addition, the application switch P has a resistance of a size inherent to the element between the source and the drain in the ON state. Therefore, when a current flows from the piezo element 12 during a period in which the application switch P is on, a voltage proportional to the current (hereinafter, test voltage MV) is generated between the source and drain of the application switch P.

  In each of the plurality of ejection mechanisms, an inspection switch M is connected between the piezo element 12 and the application switch P. The inspection switch M is provided for each ejection mechanism, and the inspection switch M is connected to the inspection terminal T of the pulse converter 11e. When the inspection switch M is turned on, the inspection voltage MV between the source and the drain of the application switch P of the ejection mechanism in which the inspection switch M is turned on is input to the inspection terminal T of the pulse converter 11e. Note that the voltage drop due to the resistance in the inspection switch M is ignored.

  As shown in FIG. 1, the head IC 11 includes a switch control data generation unit 11a, an abnormality handling unit 11b, an application switch control unit 11c, an application switch P, an inspection switch control unit 11d, an inspection switch M, a pulse conversion unit 11e, and an attenuation period measurement. A unit 11f, a voltage determination unit 11g, and an abnormality determination unit 11h. The head IC 11 is an SOC (System on a chip) or the like in which a digital signal processing circuit, an analog signal processing circuit, a RAM, and the like are included in a single semiconductor integrated circuit. The switch control data generation unit 11a outputs the discharge availability data SI to the abnormality handling unit 11b at the subsequent stage.

  The switch control data generation unit 11a outputs the discharge availability data SI to the abnormality handling unit 11b at the subsequent stage. The abnormality handling unit 11b causes the abnormal ejection mechanism, in which the ejection availability data SI is determined to be abnormal by an inspection process to be described later, to eject the ink droplet, and causes the ink ejection to the normal ejection mechanism, which is determined to be normal. When it is indicated that the ejection is not performed, the ejection propriety data SI is corrected. That is, the abnormality handling unit 11b corrects the ejection enable / disable data SI so as to cause the normal ejection mechanism to eject ink droplets instead of the abnormal ejection mechanism, and outputs the data to the subsequent application switch control unit 11c. In this embodiment, the abnormality handling unit 11b causes the normal ejection mechanism adjacent to the abnormal ejection mechanism to eject ink droplets instead of the abnormal ejection mechanism.

  FIG. 3A is a diagram showing the arrangement of the nozzles 14 on the surface (nozzle surface) facing the recording medium in the head IC 11. In this embodiment, the head IC 11 is a line head, and is provided with two nozzle rows for each ink color in which a plurality of nozzles 14 are arranged perpendicular to the conveyance direction (printing direction) of the recording medium. In each nozzle row, the arrangement interval of the nozzles 14 in the direction orthogonal to the printing direction is constant. Further, the position of the nozzle 14 in the direction orthogonal to the printing direction is shifted by a half of the arrangement interval between the nozzle rows adjacent in the printing direction. The normal ejection mechanism adjacent to the abnormal ejection mechanism ejects ink droplets of the same ink color as the abnormal ejection mechanism and has the shortest distance from the nozzle 14 (white circle) included in the abnormal ejection mechanism in the direction orthogonal to the printing direction. It is two discharge mechanisms provided with the nozzle 14 (double circle) used as (half the arrangement interval).

  The abnormality handling unit 11b acquires a determination table D2 indicating whether each of the plurality of ejection mechanisms is abnormal at each ejection timing in the print job, and ejects the ejection mechanism that ejects ink droplets at the ejection timing. It specifies based on the availability data SI. When the ejection mechanism that ejects ink droplets is an abnormal ejection mechanism, the ink ejection is caused to be ejected by a normal ejection mechanism adjacent to the abnormal ejection mechanism instead of the abnormal ejection mechanism. The abnormality determination unit 11h updates the determination table D2 for each ejection timing in the print job. Accordingly, at the (A + 1) th ejection timing, the abnormality handling unit 11b causes the normal ejection mechanism to eject ink droplets instead of the abnormal ejection mechanism that is abnormal by the abnormality determination unit 11h at the Ath ejection timing. Become. Since the discharge availability data SI is output to the discharge mechanism at each discharge timing, the piezo element 12 of the discharge mechanism is controlled based on the Ath discharge availability data SI at the Ath discharge timing in the print job. Become.

  The application switch control unit 11c includes a shift register that restores the discharge enable / disable data SI for each discharge mechanism by performing parallel conversion on the nozzle selection data serially coupled to the discharge enable / disable data SI. That is, the application switch control unit 11c has a plurality of registers corresponding to each of the plurality of ejection mechanisms, and shifts the nozzle selection data for each predetermined clock in the plurality of registers, thereby causing the plurality of registers to be registered. The discharge availability data SI is held. Then, the application switch controller 11c controls the control signal at the data output terminal to which the application switch P is connected based on the discharge availability data SI held in each of the plurality of registers in synchronization with the latch signal LAT and the switching signal CH. Is controlled to 1 or 0. Thereby, in each of the plurality of ejection mechanisms, the application switch P is turned on (control signal: 1) and turned off (control signal: 0), and whether or not the ink droplets are ejected by the piezo element 12 is switched.

  FIG. 3B is a timing chart showing the operation of the drive voltage COM and the switches P and M. In the present embodiment, the drive voltage generation circuit 22 discharges the piezo element 12 to drive the piezo element 12 so as to eject ink droplets at every ejection timing, and the piezo element so that the diaphragm 15 vibrates to the extent that ink droplets are not ejected. The drive voltage COM including the micro-vibration pulse for driving 12 is generated. Note that the potential of the voltage pattern generated by the drive voltage generation circuit 22 is a known reference potential VS in a period excluding the output period of the ejection pulse and the output period of the fine vibration pulse. The ejection timing is a period between timings when the pulse of the latch signal LAT rises. The switching signal CH is a timing signal for dividing a single ejection timing into the first to fourth periods.

  In the first period, the drive voltage COM includes an ejection pulse for ejecting a large ink droplet that forms a large dot. In the second period, the drive voltage COM includes an ejection pulse for ejecting a medium ink droplet that forms a medium dot. In the third period, the drive voltage COM includes an ejection pulse for ejecting a small ink droplet that forms a small dot. In the fourth period, the drive voltage COM includes a fine vibration pulse for causing the piezoelectric element 12 to vibrate. The volume of ink droplets is the largest for large ink droplets and the smallest for small ink droplets.

  When ejection enable / disable data SI for ejecting large ink droplets is input by the ejection mechanism, the application switch controller 11c controls the signal level of the control signal at the data output terminal so that the application switch P is turned on in the first period. (The signal level is set to 1 only in the first period). In addition, when ejection enable / disable data SI for ejecting medium ink droplets is input by the ejection mechanism, the application switch controller 11c controls the signal level of the control signal at the data output terminal so that the application switch P is turned on in the second period. (The signal level is set to 1 only in the second period). Further, when the ejection enable / disable data SI for ejecting small ink droplets is input by the ejection mechanism, the application switch control unit 11c controls the signal level of the control signal at the data output terminal so that the application switch P is turned on in the third period. (The signal level is set to 1 only in the third period). Thereby, an ejection pulse corresponding to an ink droplet having a size to be ejected can be applied to the piezo element 12. On the other hand, when ejection enable / disable data SI that does not cause ink droplets to be ejected by the ejection mechanism is input, the application switch controller 11c sets the signal level of the control signal at the data output terminal so that the application switch P is turned on in the fourth period. Control (the signal level is set to 1 only in the fourth period). Thereby, even in an ejection mechanism that does not eject ink droplets, the vibration plate 15 can be vibrated to the extent that ink droplets are not ejected, and ink retention in the ink chamber 13 can be prevented.

  As shown in FIG. 1, the switch control data generation unit 11a generates inspection control data SG and outputs the inspection control data SG to the inspection switch control unit 11d. As shown in FIG. 2B, the inspection switch control unit 11d is a shift register that converts the serial data of the inspection control data SG into parallel data and outputs the inspection control data SG to the inspection switch M provided for each ejection mechanism. The switch control data generation unit 11a selects one ejection mechanism to be inspected for each ejection timing, and creates inspection control data SG so that only the inspection switch M corresponding to the ejection mechanism is turned on. Therefore, the inspection voltage MV generated between the source and drain of the application switch P of the ejection mechanism to be inspected is input to the inspection terminal T of the pulse converter 11e. The switch control data generation unit 11a can select the same discharge mechanism as an inspection target continuously over a plurality of discharge timings.

  As shown in FIG. 3B, the inspection switch M corresponding to the ejection mechanism that is selected as an inspection target and ejects large ink droplets is a period from the end of the ejection pulse output period to the end of the first period in the first period. It is controlled by the inspection control data SG so as to be turned on only at. In addition, the inspection switch M that is selected as the inspection target and corresponds to the ejection mechanism that ejects the medium ink droplet is turned on only in the period from immediately after the ejection pulse is output in the second period to the end of the second period. Are controlled by the inspection control data SG. Further, the inspection switch M selected as the inspection target and corresponding to the ejection mechanism that ejects the small ink droplets is turned on only in the period from immediately after the ejection pulse is output in the third period to the end of the third period. Are controlled by the inspection control data SG. As a result, the inspection voltage MV indicating the state of residual vibration of the diaphragm 15 immediately after the output period of the ejection pulse that forcibly vibrates the diaphragm 15 is obtained regardless of whether large or small ink droplets are ejected. be able to. That is, in the ejection mechanism that ejects ink droplets, it is possible to obtain the inspection voltage MV that indicates the residual vibration state as the operating state of the piezo element 12 immediately after ejection of the ink droplets. In addition, a current flows between the piezo element 12 and the ground due to a change in the parasitic capacitance of the piezo element 12 due to the residual vibration of the diaphragm 15, and a test voltage proportional to the current flows between the source and drain of the application switch P. Will occur. On the other hand, since the inspection switch M is always off in the ejection mechanism that is not the inspection target, it is possible to prevent the voltage generated by the application switch P of the ejection mechanism that is not the inspection target from becoming a noise source of the inspection voltage MV.

  The pulse converter 11e is a circuit that generates the inspection pulse MP by binarizing the inspection voltage MV input to the inspection terminal T depending on whether or not it is greater than a predetermined threshold voltage. Since one end of the application switch P is connected to the ground, the potential of the inspection terminal T can be acquired as the inspection voltage MV generated between the source and drain of the application switch P. In the present embodiment, the pulse converter 11e includes three first to third amplifier circuits A1 to A3 and a switch (not shown). In the first period, the switch inputs the inspection voltage MV to the first amplifier circuit A1, in the second period, the switch inputs the inspection voltage MV to the second amplifier circuit A2, and in the third period, the switch applies the inspection voltage MV to the third period. Input to the amplifier circuit A3. The amplification factors in the first to third amplifier circuits A1 to A3 are the smallest in the first amplifier circuit A1 and the largest in the third amplifier circuit A3. That is, the smaller the volume of the ejected ink droplet, the larger the amplification factor of the inspection voltage MV. The smaller the volume of the ejected ink droplet, the smaller the amplitude of the inspection voltage MV before amplification. However, by increasing the amplification factor, the amplitude of the inspection voltage MV after amplification can include the threshold voltage. . Accordingly, by increasing the amplification factor of the inspection voltage MV as the volume of the ejected ink droplet is smaller, the inspection pulse MP corresponding to the inspection voltage MV can be generated even when the volume of the ejected ink droplet is small.

  FIG. 4A is a timing chart showing the inspection voltage MV and the inspection pulse MP. As shown in FIG. 4A, the inspection voltage MV has a periodic waveform whose amplitude is attenuated as time t passes. When the residual vibration is attenuated as time t passes and the amplitude of the inspection voltage MV after amplification does not include the threshold voltage (two-dot chain line), the signal level of the inspection pulse MP does not change. The attenuation period measurement unit 11f specifies the period from the end time of the ejection pulse output period to the time when the signal level of the inspection pulse MP last changed as the attenuation period q.

  The voltage determination unit 11g reads the normal range of the attenuation period q for each of the first to third periods from the determination condition data D1, and when the attenuation period q measured by the attenuation period measurement unit 11f belongs to the normal range, the voltage determination unit 11g It is determined that the MV is normal. In the third period in which the small ink droplets are ejected, the amplitude of the piezo element 12 (the diaphragm 15) is smaller than in the first and second periods in which the large ink droplets and the medium ink droplets are ejected. q becomes shorter. However, since the amplification factors of the first to third amplifier circuits A1 to A3 are different from each other, the normal range of the attenuation period q in the third period is not necessarily set to be shorter than the normal range of the attenuation period q in the first period. Not necessarily. Since the attenuation period q becomes shorter as the viscosity of the ink in the ink chamber 13 becomes higher, the fact that the attenuation period q belongs to the normal range means that the viscosity of the ink in the ink chamber 13 is normal. That is, in this embodiment, the abnormal discharge mechanism means that the viscosity of the ink in the ink chamber 13 is abnormal.

  The abnormality determination unit 11h acquires the inspection control data SG from the discharge availability data generation circuit 21, and specifies the inspection target discharge mechanism based on the inspection control data SG. The abnormality determination unit 11h records the determination result of the inspection voltage MV for the ejection mechanism to be inspected in the determination table D2.

  FIG. 4B is a diagram illustrating a determination table D2 recorded by the abnormality determination unit 11h. In the determination table D2 of FIG. 4B, the inspection result is recorded for each combination of a unique number n (maximum value N) for each of the plurality of discharge mechanisms and a discharge timing number A corresponding to the discharge timing. In the determination table D2 of FIG. 4B, the number n column corresponding to the ejection mechanism other than the ejection mechanism to be inspected is hatched. In addition, a pause character is added to the column of the ejection timing number A when the ejection mechanism to be inspected did not eject ink droplets. On the other hand, in the column of the ejection timing number A when the ejection mechanism to be inspected ejects ink droplets, large to small characters indicating the size of the ejected ink droplets and the determination of the inspection voltage MV (attenuation period q) are performed. The result is OK (when normal) or NG (when abnormal).

  When the inspection voltage MV is normal, the abnormality determination unit 11h temporarily determines that the discharge mechanism is normal, and adds 1 to the normal number of times for the discharge mechanism. Then, the abnormality determination unit 11h determines that the discharge mechanism is normal for the discharge mechanism in which the number of normal times is a predetermined normal threshold. In the present embodiment, the normal threshold is 2 times. For example, in the determination table D2 of FIG. 4B, the inspection voltage MV is normal at the ejection timings 205 and 206 (= A) when the ejection mechanism No. 31 (= n) ejects the small ink droplet and the large ink droplet, respectively. Therefore, the normal number of times becomes 2 at the 206th ejection timing. Accordingly, it is determined that the 31st discharge mechanism is normal at the 206th discharge timing. In the determination table D2 of FIG. 4B, a letter “O” is attached to the column corresponding to the number n of the ejection mechanism determined to be normal. Similarly, in the determination table D2 of FIG. 4B, the inspection voltage MV is set at the discharge timings 207 and 209 (= A) when the large ink droplet and the medium ink droplet are discharged by the discharge mechanism 32 (= n), respectively. It is determined to be normal, and it is determined that the 32 (= n) discharge mechanism is normal at the 209 discharge timing.

  On the other hand, in the determination table D2 of FIG. 4B, it is determined that the inspection voltage MV is abnormal at the discharge timing of number 210 (= A) when the medium ink droplet is discharged by the number 33 (= n) discharge mechanism, It is determined that the 33 (= n) discharge mechanism is abnormal at the 210 discharge timing. That is, the abnormality determination unit 11h determines that the ejection mechanism is abnormal when the number of abnormalities, which is the number of times that the inspection voltage MV is determined to be abnormal, becomes 1 (abnormal threshold) or more. In the determination table D2 of FIG. 4B, a column corresponding to the number n of the ejection mechanism determined to be abnormal is marked with a cross.

  When it is determined that the inspection target ejection mechanism is normal or abnormal, the abnormality determination unit 11h permits the next ejection mechanism to be selected as the inspection target. In response to this, the switch control data generation unit 11a generates inspection control data SG for turning on the inspection switch M corresponding to the discharge mechanism to be inspected immediately after the discharge pulse at the next discharge timing. On the other hand, the abnormality determination unit 11h does not allow the next discharge mechanism to be selected as the inspection target when it cannot be determined that the inspection target discharge mechanism is normal or abnormal. In response to this, the switch control data generation unit 11a continues to generate inspection control data SG for turning on the inspection switch M corresponding to the current discharge mechanism to be inspected immediately after the discharge pulse at the next discharge timing. Therefore, the abnormality determination unit 11h repeats the process of determining whether or not the inspection voltage MV is normal for the ejection mechanism until it is determined that the ejection mechanism to be inspected is normal or abnormal.

  In the configuration of the present embodiment described above, when the drive voltage COM is applied to the piezo element 12, the source and the drain of the application switch P are conducted, and a specific resistance is generated between the source and the drain of the application switch P. . Therefore, when the drive voltage COM is applied to the piezo element 12, a current flows between the source and drain of the application switch P in accordance with the residual vibration of the piezo element 12, and an inspection voltage proportional to the current is generated. That is, the abnormality determination unit 11h can obtain an inspection voltage corresponding to the residual vibration of the piezo element 12, and can determine whether or not the ejection mechanism is abnormal based on the inspection voltage. Since the inspection switch M is provided in each of the plurality of ejection mechanisms, the amount of current flowing through the inspection switch M can be suppressed. Therefore, the inspection switch M can be realized with a small current element, and the head IC 11 including the inspection switch M can be downsized. Furthermore, since the inspection switch M is provided for each ejection mechanism, the voltage generated by the residual vibration of the piezo element 12 in the ejection mechanism that is not the inspection target can be cut off by the inspection switch M. Accordingly, the ink droplets can be ejected by the ejection mechanism that is not the inspection target without interfering with the inspection of the ejection mechanism to be inspected, and the ejection mechanism can be inspected even during a period during which an arbitrary print job is executed.

  In each of the plurality of ejection mechanisms, one end of the application switch P is set to a known potential (ground), and the other end of the application switch P is connected to the piezo element 12. Then, the inspection switch M switches whether the other end of the application switch P is connected to the inspection terminal T or not. In this way, if one end of the application switch P is set to a known potential, the potential at the other end of the application switch P is measured at the inspection terminal T, so that the difference between the measured potential and the known potential is applied. An inspection voltage between the source and drain of the switch P can be obtained. In particular, in each of the plurality of ejection mechanisms, since one end of the application switch P is connected to the ground as a known potential, the inspection voltage can be easily obtained from the difference between the ground potential and the potential at the other end of the application switch P.

  The abnormality handling unit 11b applies ink droplets to the normal ejection mechanism instead of the abnormal ejection mechanism when the ejection enable / disable data SI indicates that the abnormal ejection mechanism ejects ink droplets and the normal ejection mechanism does not eject ink droplets. Discharge. That is, the abnormality handling unit 11b causes the normal ejection mechanism that can normally eject ink droplets to eject ink droplets instead of the abnormal ejection mechanism that cannot normally eject ink droplets. Thereby, even when an abnormal ejection mechanism is present, it is possible to prevent abnormal ink droplets from being ejected. Further, when an abnormal ejection mechanism is detected when ejecting ink droplets based on the A-th ejection availability data SI, ink droplets are ejected based on the (A + 1) th ejection availability data SI in the same print job. When ejecting (next ejection timing), ink droplets can be ejected to the normal ejection mechanism instead of the abnormal ejection mechanism. Therefore, it is possible to suppress deterioration of the printed image. Also, there is no need to cancel the print job. Furthermore, since the abnormality determination unit 11h and the abnormality handling unit 11b are provided in the ejection head 10, it is not necessary to generate the ejection propriety data SI for causing the normal ejection mechanism to eject ink droplets instead of the abnormal ejection mechanism. Therefore, it is not necessary to notify the determination result of the abnormal ejection mechanism to the main substrate or the like outside the ejection head 10 so as to generate ejection propriety data SI that causes the normal ejection mechanism to eject ink droplets instead of the abnormal ejection mechanism. There is no need to provide a signal line for notification.

  In the above configuration, the voltage determination unit 11g determines whether or not the decay period q of the inspection voltage MV is abnormal using different determination conditions for each volume of ink droplets ejected by the piezo element 12. Although the normal range of the attenuation period q of the residual vibration of the piezo element 12 may be different for each volume of ink droplets ejected by the piezo element 12, it is determined whether or not the inspection voltage MV is abnormal depending on an appropriate determination condition. it can. In addition, the abnormality determination unit 11h can determine whether or not the ejection mechanism is abnormal when ejecting any volume of ink droplets. Therefore, for example, there is no need to wait for an opportunity for the ejection mechanism to eject a large ink droplet, and the abnormality determination unit 11h can determine whether or not the ejection mechanism is abnormal at an early stage. Further, even when ink droplets of a plurality of volumes of ink droplets can be ejected during execution of an arbitrary print job, the inspection of the ejection mechanism can be completed at an early stage.

  Here, the smaller the volume of ink droplets ejected by the piezo element 12, the weaker the piezo element 12 is driven, the smaller the amplitude of the inspection voltage MV. Therefore, the pulse converter 11e as the inspection voltage acquisition unit increases the amplification factor of the first to third amplifier circuits A1 to A3 as the piezoelectric element 12 ejects a small volume of ink droplets. Thereby, even when the piezo element 12 ejects a small ink droplet, it is possible to obtain an inspection voltage MV having an amplitude (including a threshold voltage) that can be determined whether or not it is abnormal.

  Further, the abnormality determination unit 11h determines the number of times that the inspection voltage MV is determined to be normal when a large ink droplet is ejected (determination result), and the inspection voltage MV is normal when a medium ink droplet is ejected. The number of times determined to be present (determination result) and the number of times that the inspection voltage MV is determined to be normal when a small ink droplet is ejected (determination result) are sequentially summed (S135) to obtain the normal number of times. Based on this, it is determined whether or not the ejection mechanism is abnormal. Thereby, even when ink droplets of a plurality of volumes of ink droplets can be ejected during execution of an arbitrary print job, the inspection of the ejection mechanism can be completed at an early stage.

  Here, the greater the number of times that the inspection voltage MV is determined to be normal, the higher the reliability that the inspection voltage MV is normal. As in the present embodiment, the abnormality determination unit 11h determines that the ejection mechanism is normal when the number of normal times, which is the number of times that the inspection voltage MV is tentatively determined to be normal, is equal to or greater than a predetermined normal threshold (2 times). By determining that it is, it is possible to perform a highly reliable inspection.

(1-2) Inspection process:
FIG. 5 is a flowchart of the inspection process executed by the head IC 11 of the ejection head 10. The inspection process is a loop process that is executed at each ejection timing during execution of a print job. The print job that can execute the inspection process is not particularly limited, and the inspection process can be executed in a print job that forms an arbitrary print image. The switch control data generation unit 11a selects a discharge mechanism to be inspected (S100). For example, the switch control data generation unit 11a may select the discharge mechanism in ascending order of the number n. If the inspection process for all the ejection mechanisms has not been completed at the time of the previous print job, the ejection mechanism that has not been inspected at the time of the previous print job by referring to the determination table D2. May be selected. Next, the switch control data generation unit 11a generates inspection control data SG for turning on only the inspection switch M corresponding to the ejection mechanism to be inspected, and outputs the inspection control data SG to the inspection switch control unit 11d (S105). Thereby, the inspection control data SG is held by the shift register of the inspection switch control unit 11d.

  Next, the switch control data generation unit 11a acquires the discharge availability data SI from the discharge availability data generation circuit 21 (S110). In other words, the switch control data generation unit 11a acquires the discharge availability data SI for the discharge mechanism to discharge the current ink droplet. When the ejection propriety data SI is acquired, the abnormality handling unit 11b executes an abnormality handling process (described later). In this abnormality handling process, the abnormality handling unit 11b corrects the discharge feasibility data SI, and after the step S115, each process is performed on the corrected ejection propriety data SI. Then, when the pulse of the latch signal LAT rises after the abnormality handling process, ink droplets are ejected from all ejection mechanisms designated to eject ink droplets in the ejection enable / disable data SI including the ejection mechanism to be inspected. The

  The pulse converter 11e and the attenuation period measurement unit 11f acquire the inspection voltage MV and measure the attenuation period q in which the inspection voltage MV vibrates (S115). That is, the inspection voltage MV is input to the inspection terminal T of the pulse converter 11e from the application switch P of the ejection mechanism to be inspected via the inspection switch M in the period immediately after the ejection pulse. Then, the pulse conversion unit 11e amplifies the inspection voltage MV by the first to third amplifier circuits A1 to A3 corresponding to the volume of the ink droplets ejected by the ejection mechanism to be inspected, and uses the amplified inspection voltage MV. Convert to inspection pulse MP. Further, the attenuation period measuring unit 11f measures the period from the end of the ejection pulse output period to the time t when the signal level of the inspection pulse MP last changed as the attenuation period q. Next, the voltage determination unit 11g determines whether or not the decay period q is abnormal (S120). That is, the voltage determination unit 11g determines that the attenuation period q is abnormal when it does not belong to the normal range defined in the determination condition data D1, and determines that the attenuation period q is normal when it belongs to the normal range. judge.

  When the decay period q is abnormal (S120: Y), the abnormality determination unit 11h determines that the ejection mechanism to be inspected is abnormal (S125). Then, the abnormality determining unit 11h determines whether or not all the ejection mechanisms have been selected as inspection targets (S130). If all the ejection mechanisms have not been selected as inspection targets (S130: N), the abnormality determination unit 11h returns to Step S100. That is, the abnormality determination unit 11h allows the switch control data generation unit 11a to select the next discharge mechanism as an inspection target, and causes the process (S105 to S105) for the next discharge mechanism to be executed. On the other hand, when all the ejection mechanisms are selected as inspection targets (S130: Y), the abnormality determination unit 11h ends the inspection process. If the print job is completed before the end of the inspection process, the determination table D2 at that time may be held, and the inspection process may be continued in the next print job.

  On the other hand, when the decay period q is normal (S120: N), the abnormality determination unit 11h provisionally determines that the ejection mechanism to be inspected is normal, and adds 1 to the normal count (S135). Note that when the discharge mechanism is first selected as an inspection target, the normal number of times for the discharge mechanism is reset to zero. Then, the abnormality determination unit 11h determines whether or not the normal number of times of the ejection mechanism to be inspected is equal to the normal threshold (2) (S140).

  When the normal number of times for the ejection mechanism to be inspected is equal to the normal threshold (2) (S140: Y), the abnormality determination unit 11h determines that the ejection mechanism to be inspected is normal (S145). Then, the abnormality determining unit 11h determines whether or not all the ejection mechanisms have been selected as inspection targets (S130). On the other hand, when the normal number of times for the ejection mechanism to be inspected is not equal to the normal threshold value (2) (S140: N), the abnormality determination unit 11h does not select the next ejection mechanism as the inspection target in step S100, and the step Return to S105. That is, the abnormality determination unit 11h prohibits the switch control data generation unit 11a from selecting the next discharge mechanism as an inspection target, and repeatedly executes the process (S110) for the same discharge mechanism.

(1-3) Abnormal response processing:
FIG. 6 is a flowchart of the abnormality handling process executed by the abnormality handling unit 11b. The abnormality handling process is a process that is executed every time the ejection propriety data SI is acquired in the inspection process of FIG. When the discharge enable / disable data SI is acquired in step S110 of FIG. 5, the abnormality handling unit 11b acquires the determination table D2 updated at the previous discharge timing. That is, if the discharge availability data SI at the (A + 1) th discharge timing is acquired in step S110 of FIG. 5, the abnormality handling unit 11b acquires the determination table D2 updated at the Ath discharge timing.

  The abnormality handling unit 11b identifies an operating ejection mechanism that is an ejection mechanism that should eject ink droplets based on the current ejection propriety data SI, and selects one of the operating ejection mechanisms (S210). Next, the abnormality handling unit 11b determines whether or not the selected operating discharge mechanism is an abnormal discharge mechanism determined to be abnormal in the determination table D2 (S230). If the selected operating discharge mechanism is not the abnormal discharge mechanism determined to be abnormal in the determination table D2 (S230: N), step S250 is performed without correcting the discharge availability data SI for the selected operating discharge mechanism. Execute. The abnormality handling unit 11b determines whether or not all the operation discharge mechanisms have been selected (S250). If not all the operation discharge mechanisms have been selected (S250: N), the process returns to step S210, and the next operation discharge mechanism is selected. In the abnormality handling process, it is assumed that an uninspected ejection mechanism (a ejection mechanism in which neither abnormality nor normality is determined) is not abnormal.

  On the other hand, when the selected operating discharge mechanism is an abnormal discharge mechanism that is determined to be abnormal in the determination table D2 (S230: Y), the abnormality handling unit 11b determines whether the adjacent operating discharge mechanism adjacent to the selected operating discharge mechanism. It is determined whether or not all of the abnormal ejection mechanisms are determined to be abnormal in the determination table D2 (S260). That is, as shown in FIG. 3A, the abnormality handling unit 11b ejects ink droplets of the same ink color as the abnormal ejection mechanism, and the distance from the nozzle 14 (white circle) provided in the abnormal ejection mechanism in the direction orthogonal to the printing direction. It is determined whether or not the two discharge mechanisms each having the nozzle 14 (double circle) having the shortest (half of the arrangement interval) are abnormal discharge mechanisms. If all the adjacent ejection mechanisms are abnormal ejection mechanisms (S260: Y), the abnormality handling unit 11b executes step S250 without correcting the ejection availability data SI.

  On the other hand, if at least one of the adjacent discharge mechanisms is not an abnormal discharge mechanism (S260: N), the abnormality handling unit 11b determines whether all of the adjacent discharge mechanisms that are not abnormal discharge mechanisms are operating discharge mechanisms (S270). ). If at least one of the adjacent discharge mechanisms that are not the abnormal discharge mechanism is not the operating discharge mechanism (S270: N), the abnormality handling unit 11b performs the discharge availability data SI for the selected operating discharge mechanism and the active discharge even in the abnormal discharge mechanism. The discharge availability data SI for adjacent discharge mechanisms that are not mechanisms is exchanged (S280). As a result, it is possible to correct the ejection propriety data SI so that the ink droplets are ejected to the normal adjacent ejection mechanism instead of the selected abnormal operation ejection mechanism. When there are a plurality of adjacent discharge mechanisms that are neither the abnormal discharge mechanism nor the active discharge mechanism, the abnormality handling unit 11b may exchange any of these adjacent discharge mechanisms with the discharge availability data SI.

  On the other hand, when all of the adjacent ejection mechanisms that are not abnormal ejection mechanisms are operating ejection mechanisms (S270: Y), the abnormality handling unit 11b executes step S250 without correcting the ejection propriety data SI. If the normal ejection mechanism cannot eject ink droplets instead of the abnormal ejection mechanism (S260: Y, S270: Y), the abnormality handling unit 11b does not eject abnormal ink droplets from the operating ejection mechanism. The discharge availability data SI may be corrected. Further, when ink droplets cannot be ejected by the normal ejection mechanism instead of the abnormal ejection mechanism (S260: Y, S270: Y), the abnormality handling unit 11b widens the existence range of the nozzles 14 to be satisfied by the adjacent ejection mechanism. May be. When all the adjacent ejection mechanisms that are not abnormal ejection mechanisms are operating ejection mechanisms (S270: Y), the abnormality handling unit 11b increases the volume of ink droplets ejected by any of the adjacent ejection mechanisms that are not abnormal ejection mechanisms. As described above, the discharge availability data SI for the adjacent discharge mechanism may be modified.

(2) Modification 1:
FIG. 7A is a schematic diagram illustrating the structure of the ejection mechanism provided in the ejection head 10 of the first modification, and FIG. 7B is a circuit diagram of a part of the ejection head 10 of the first modification. As shown in FIG. 7A, in Modification 1, each discharge mechanism includes a normal part, a spare part, and a nozzle 14. The normal portion includes a piezo element 12 a, an ink chamber 13 a, and a vibration plate 15 a, and the ink chamber 13 a communicates with the nozzle 14. The spare part includes a spare piezo element 12 b, a spare ink chamber 13 b, and a spare diaphragm 15 b, and the ink chamber 13 b also communicates with the nozzle 14. In the ejection mechanism, the normal part and the spare part have a symmetrical structure with respect to the central nozzle 14 in the plane of FIG. 7A. Since the ink chamber 13a and the preliminary ink chamber 13b communicate with the nozzle 14, ink is supplied to the nozzle 14 from each of the ink chamber 13a and the preliminary ink chamber 13b.

  In FIG. 7B, a piezo element 12a and a spare piezo element 12b are provided in a single ejection mechanism (one-dot chain line), and each of the piezo element 12a and the spare piezo element 12b is connected to the ground and the drive voltage generation circuit 22. Are connected in series. An application switch P1 and a preliminary application switch P2 are connected in series between each of the piezoelectric element 12a and the preliminary piezoelectric element 12b and the ground. Accordingly, when the application switch P1 is turned on, the drive voltage COM is applied to the piezo element 12a, and when the preliminary application switch P2 is turned on, the drive voltage COM is applied to the preliminary piezo element 12b. The application switch P1 and the preliminary application switch P2 are connected to the application switch control unit 11c via the switching circuit C, and are switched on and off by the application switch control unit 11c and the switching circuit C. A test switch M for switching whether to output the test voltage MV from between the application switch P1 and the drive voltage generation circuit 22 is connected. On the other hand, the inspection switch M corresponding to the preliminary application switch P2 is not provided.

  FIG. 8A is a timing chart illustrating the drive voltage COM and the operations of the switches P1, P2, and M in the normal ejection mechanism in the first modification. The latch signal LAT, the switching signal CH, and the drive voltage COM are the same as in the above embodiment. The switching circuit C switches the control signal output from the data output terminal of the application switch control unit 11c to each of the application switch P1 and the preliminary application switch P2, depending on whether or not the residual vibration of the piezo element 12a is normal. Switch.

  When the residual vibration of the piezo element 12a is normal, the application switch controller 11c and the switching circuit C control the application switch P1 based on the discharge availability data SI. That is, similarly to the above-described embodiment, when the discharge enable / disable data SI indicating that large to small ink droplets are discharged is output, the application switch P1 is set in the first to third periods corresponding to the volume of the ink droplets. When the ejection enable / disable data SI indicating that the ink droplet is not ejected is output, the application switch P1 is turned on in the fourth period. When the ejection mechanism is normal, the inspection switch M is turned on immediately after the ejection pulse output period corresponding to the volume of the ejected ink droplet, as in the first embodiment. Further, when the residual vibration of the piezo element 12a is normal, the application switch controller 11c and the switching circuit C make the preliminary application switch P2 based on the minute vibration data VI (FIG. 7B) independent of the discharge enable / disable data SI. Control. That is, the preliminary application switch P2 is always turned on in the fourth period of the discharge timing without depending on the discharge availability data SI.

  FIG. 8B is a timing chart illustrating the drive voltage COM and the operation of each of the switches P1, P2, and M in the abnormal ejection mechanism in the first modification. When the ejection mechanism is abnormal, the application switch controller 11c and the switching circuit C control the preliminary application switch P2 based on the ejection availability data SI. That is, when ejection enable / disable data SI indicating that large to small ink droplets are ejected is output, the preliminary application switch P2 is turned on in the first to third periods corresponding to the volume of the ink droplets, and the ink droplets are ejected. When the ejection enable / disable data SI indicating that ejection is not performed is output, the preliminary application switch P2 is turned on in the fourth period. Further, when the ejection mechanism is abnormal, the application switch controller 11c and the switching circuit C control the application switch P1 based on the minute vibration data VI (FIG. 7B) independent of the ejection availability data SI. That is, the application switch P1 is always turned on only in the fourth period without depending on the discharge availability data SI. When the discharge mechanism is abnormal, the inspection switch M is always turned off.

  FIG. 9A is a flowchart of the abnormality handling process according to the first modification. Also in the first modification, the abnormality handling process is a process executed during the inspection process (after step S110 in FIG. 5) during the execution of the print job. When the discharge availability data SI is acquired in step S110 of FIG. 5, the abnormality handling unit 11b acquires the determination table D2 updated at the previous discharge timing (S400). Next, the abnormality handling unit 11b selects a discharge mechanism to be processed (S410). Then, the abnormality handling unit 11b determines whether or not the discharge mechanism to be processed is determined to be abnormal (S420).

  When it is determined that the processing target ejection mechanism is abnormal (S420: Y), the abnormality handling unit 11b causes the switching circuit C to eject ink droplets by driving the spare piezo element 12b for the processing target ejection mechanism. (S430). That is, an abnormality response signal for causing the preliminary application switch P2 to output a control signal based on the discharge availability data SI and causing the application switch P1 to output a control signal based on the minute vibration data VI independent of the discharge availability data SI. Is output to the switching circuit C. On the other hand, when it is not determined that the discharge mechanism to be processed is abnormal (S420: N), the abnormality handling unit 11b outputs an abnormality response signal for switching the switching circuit C for the discharge mechanism to be processed. Instead, the next ejection mechanism is selected as a processing target (S440, S410). That is, the control signal based on the discharge availability data SI is output to the application switch P1, and the control signal based on the minute vibration data VI independent of the discharge availability data SI is output to the preliminary application switch P2.

(3) Modification 2:
FIG. 9B shows an example of the determination table D2 recorded in the second modification. In FIG. 9B, the numerical value described in the column of the discharge mechanism that is the inspection target represents the total index value, not the normal number of times. When the inspection voltage MV acquired in the first period is normal, the abnormality determination unit 11h does not add 1 to the normal number of times, but uses 2 (as the index value obtained by multiplying the normal number of times by the weighting factor 2). = 2 × 1) is added to the total index value. When the inspection voltage MV acquired in the second period is normal, the abnormality determination unit 11h adds 1 (= 1 × 1) to the total index value as an index value obtained by multiplying the normal number of times by one weighting factor 1. . Furthermore, when the inspection voltage MV acquired in the third period is normal, the abnormality determination unit 11h uses 0.5 (= 0.5 × 1) as an index value obtained by multiplying the normal number of times by a weighting factor of 0.5. ) Is added to the overall index value. That is, the abnormality determination unit 11h calculates a total index value obtained by adding the index values obtained by multiplying the number of times that the inspection voltage MV is determined to be normal by a weighting factor that is larger as the volume of the ink droplet is larger. Then, when the abnormality determining unit 11h is equal to or greater than 2 which is a predetermined normal threshold, it is determined that the ejection mechanism to be inspected is normal.

  In the example of FIG. 9B, if the number of normal times when the inspection voltage MV becomes normal when a large ink droplet is ejected is one or more, it is determined that the ejection mechanism is normal. Further, if the normal number of times that the inspection voltage MV becomes normal when the medium ink droplet is ejected is 2 or more, it is determined that the ejection mechanism is normal. Further, if the normal number of times that the inspection voltage MV becomes normal when a small ink droplet is ejected is 4 or more, it is determined that the ejection mechanism is normal. In other words, in the example of FIG. 11B, the smaller the volume of the ejected ink droplet, the larger the normal number threshold for determining that the ejection mechanism is normal.

  As described above, when a small ink droplet is ejected, the inspection voltage MV is amplified by the largest amplification factor. Therefore, when a small ink droplet is ejected, even when a minute noise voltage is mixed in the inspection voltage MV. A pulse corresponding to the noise voltage can appear in the inspection pulse MP. That is, the smaller the ink droplets ejected when the inspection voltage MV is acquired, the higher the possibility that a noise component appears in the inspection pulse MP, and the reliability of the determination result of the inspection voltage MV based on the inspection pulse MP becomes lower. On the contrary, the larger the ink droplet ejected when the inspection voltage MV is acquired, the lower the possibility that a noise component appears in the inspection pulse MP, and the reliability of the determination result of the inspection voltage MV based on the inspection pulse MP becomes higher. . Therefore, by determining whether or not the ejection mechanism is normal based on a total index value obtained by summing index values obtained by multiplying a larger weight coefficient as the ink droplet size is larger, a highly reliable test voltage is obtained. It is possible to determine whether or not the ejection mechanism is normal with emphasis on the MV determination result.

(4) Other variations:
In the above embodiment, the inspection apparatus inspects the ejection mechanism that ejects ink droplets. However, the ejection mechanism that ejects droplets other than ink droplets may be inspected. In other words, the ejection mechanism may form a planar structure or a three-dimensional structure with the ejected droplets, and the droplets may be any material constituting the planar structure or the three-dimensional structure. Furthermore, the discharge mechanism may discharge a processing liquid for performing processing (cleaning, etching, etc.) at the landing position of the droplet. Further, in the embodiment, the inspection process is performed during execution of an arbitrary print job. However, the printer 1 may perform the inspection process while printing a predetermined inspection image. Although the inspection process and the abnormality handling process are performed in parallel, the printer 1 may execute only the inspection process and cancel the print job when there is an abnormal ejection mechanism. Furthermore, the droplets are not limited to those ejected by pressurization due to mechanical changes of the piezoelectric element, but may be ejected by pressurization due to the generation of bubbles.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 10 ... Discharge head, 11 ... Head IC, 11a ... Switch control data generation part, 11b ... Abnormal response part, 11c ... Application switch control part, 11d ... Inspection switch control part, 11e ... Pulse conversion part, 11f ... Decay period measurement unit, 11g ... voltage determination unit, 11g ... pulse conversion unit, 11g ... voltage determination unit, 11h ... abnormality determination unit, 12 ... piezo element, 13 ... ink chamber, 14 ... nozzle, 15 ... diaphragm, 20 ... Main substrate, 21... Ejection enable / disable data generation circuit, 22... Drive voltage generation circuit, A1 to A3... Amplification circuit, C. Switching circuit, CH... Switching signal, COM ... drive voltage, D1. , M ... inspection switch, MP ... inspection pulse, MV ... inspection voltage, P ... application switch, SI ... discharge enable / disable data, T ... inspection terminal, VI ... fine vibration data, VS ... base Potential.

Claims (4)

An inspection apparatus for a droplet discharge device comprising a discharge mechanism including a drive element for discharging a droplet from a nozzle,
Inspection voltage acquisition means for acquiring an inspection voltage indicating an operation state of the drive element that discharges a droplet;
When the driving element discharges a first volume droplet, and when the driving element discharges a second volume droplet smaller than the first volume, the inspection voltage is set using different determination conditions. Voltage determination means for determining whether or not there is an abnormality,
When the inspection voltage is abnormal, an abnormality determination unit that determines that the discharge mechanism is abnormal;
An inspection apparatus comprising: The inspection voltage acquisition means includes an amplification circuit that amplifies the inspection voltage output from the driving element, and the amplification factor of the amplification circuit when the driving element discharges the second volume droplet, Greater than the amplification factor of the amplifier circuit when the drive element ejects the first volume of droplets;
The inspection apparatus according to claim 1. The abnormality determination unit includes a first determination result that is a determination result of the inspection voltage when the driving element discharges the first volume droplet, and the driving element discharges the second volume droplet. Determining whether or not the discharge mechanism is abnormal by combining the second determination result which is the determination result of the inspection voltage in the case;
The inspection apparatus according to claim 1 or 2. The abnormality determination unit determines whether the discharge mechanism is abnormal by placing importance on the first determination result rather than the second determination result.
The inspection apparatus according to claim 3.

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