JP4696817B2 - Droplet discharge device - Google Patents

Description

  The present invention relates to a droplet discharge device, and in particular, a pressure generation chamber filled with a liquid, a nozzle for discharging a droplet of the liquid in communication with the pressure generation chamber, and the pressure generation chamber by being vibrated. The present invention relates to a droplet discharge device including a droplet ejector having an actuator that changes the volume of the droplet to discharge the droplet from the nozzle.

  Conventionally, a pressure generating chamber filled with ink is volume-changed (expanded / contracted) using an actuator such as a piezoelectric element, and a nozzle formed in communication with the pressure generating chamber by a change in internal pressure due to this volume change. 2. Related Art An ink jet recording apparatus (so-called ink jet printer) including an ink jet recording head that discharges ink droplets from the tip is known.

  By the way, in recent years, ink jet recording apparatuses have a tendency to increase printing speed. For this reason, an inkjet recording head that can form an image in a wider area in a shorter time is used by elongating the inkjet recording head, increasing the number of nozzles per inkjet recording head, and arranging them in a matrix. It is getting to be.

  In such an ink jet recording head having a plurality of nozzles, piezoelectric elements that eject ink droplets one by one to each nozzle are required, and the same number of piezoelectric elements as the nozzles are provided.

  By the way, in the ink jet recording head as described above, unintended bubbles may be generated in the pressure generating chamber. In this case, normal ink droplets cannot be ejected, resulting in a decrease in the quality of the recorded image. was there. For this reason, many ink jet recording apparatuses of this type are provided with a maintenance unit that performs a suction recovery operation (maintenance) on the nozzles at a predetermined timing. The cause of the bubbles is that an abnormal impact is applied to the ink jet recording head during the recording operation of the ink jet recording apparatus or during standby so that the air bubbles are sucked from the nozzles, and driving for driving the actuator during the recording operation. By superimposing noise on the signal, the normal vibration of the ink meniscus in the nozzle is disturbed, bubbles are sucked from the nozzle, air dissolved in the ink is deposited, non-conformity of the ink jet recording apparatus Many things are conceivable, such as a change in ambient temperature during operation, thermal expansion or contraction of ink, and air bubbles being sucked from the nozzles.

  However, even when the suction recovery operation is performed using the maintenance unit, when bubbles are attached to the inner wall of the pressure generating chamber or when the ink liquid in the pressure generating chamber is present at the corner where the ink liquid tends to stay, etc. However, the bubbles could not be removed sufficiently.

Therefore, in order to solve this problem, Patent Literature 1, Patent Literature 2, and Patent Literature 3 describe a technique for driving a means for generating pressure in the pressure generating chamber during the suction recovery operation to excite the bubbles. In particular, Patent Document 1 discloses a technique for removing bubbles more effectively by sweeping (sweeping) the drive frequency of the means for generating pressure in the vicinity of the resonance frequency of the recording head. .
Japanese Patent No. 2525565 JP-A-3-274165 JP-A-8-169124

  As an example, as shown in FIG. 17, the resonance frequency of the bubble greatly varies depending on the diameter of the bubble. Therefore, the natural period of the ejector that includes the pressure generation chamber and the nozzle and discharges ink droplets also depends on the diameter of the bubble. It changes a lot.

  FIG. 18A shows the natural frequency (reciprocal of the natural period) of each ejector when bubbles are not generated in each pressure generating chamber of the ink jet recording head having a large number of ejectors. ) Shows an example of an actual measurement result of frequency), and FIG. 18B shows an example of an actual measurement result of the natural frequency of each ejector when bubbles are generated in each pressure generating chamber of the ink jet recording head. Has been. In the example shown in the figure, the natural frequency when bubbles are not generated is about 75 (kHz), whereas the natural frequency when bubbles are generated is about 140 (kHz). The frequency is about twice that of the case where it does not occur.

  However, since the technique disclosed in Patent Document 1 does not consider such a change in the natural period of the ejector in accordance with the bubble diameter, the natural period of the ejector during the suction recovery operation is included. When the natural period is not included, it is not always possible to sweep, and as a result of not being able to obtain a sufficient bubble removal effect, there is a problem that bubbles may not be removed. .

  On the other hand, in order to perform sweeping so as to include the natural period of the actual ejector during the suction recovery operation, it is necessary to significantly widen the sweep range so that the bubble diameter from the minimum value to the maximum value is included. Therefore, there arises a new problem that the period of the suction recovery operation becomes long.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a droplet discharge device that can effectively remove bubbles in a short time.

In order to achieve the above object, a droplet discharge device according to claim 1 is a pressure generation chamber filled with a liquid, a nozzle that communicates with the pressure generation chamber and discharges a droplet of the liquid, and is vibrated. A droplet discharge head having a droplet ejector having an actuator for changing the volume of the pressure generating chamber to discharge the droplet from the nozzle, and a suction recovery means for performing a suction recovery operation on the nozzle Storage means for preliminarily storing reference natural period information indicating the natural period of the droplet ejector at normal time, measuring means for measuring the natural period of the droplet ejector at a predetermined timing, and the measuring means It is determined whether or not the natural period measured by is separated from the natural period indicated by the reference natural period information stored in the storage means by a predetermined value or more. Determining means for determining whether or not there is an abnormality in the droplet ejector, and controlling the suction recovery means to perform the suction recovery operation when the determination means determines that there is an abnormality. And a control means for controlling the actuator so as to vibrate at the natural period measured by the measuring means simultaneously with the suction recovery operation and not to vibrate at a period other than the natural period .

  The droplet discharge device according to claim 1, wherein a pressure generation chamber filled with a liquid, a nozzle that communicates with the pressure generation chamber to discharge a droplet of the liquid, and the pressure generation chamber by being vibrated. A droplet discharge head including a droplet ejector having an actuator for changing the volume of the droplet from the nozzle and a suction recovery means for performing a suction recovery operation on the nozzle. .

  Here, in the present invention, reference natural period information indicating the natural period of the droplet ejector at the normal time is stored in advance by the storage means. The storage means includes a RAM (Random Access Memory), an EEPROM (Electrically Erasable and Programmable Read Only Memory), a semiconductor storage element such as a flash EEPROM (Flash EEPROM), a smart media (SmartMedia (registered trademark)), a flexible Various types of storage means such as a portable recording medium such as a disk, a fixed recording medium such as a hard disk, or an external storage device provided in a server computer connected to a network are included.

  In the present invention, the natural period of the droplet ejector is measured at a predetermined timing by the measuring unit, and the natural period measured by the measuring unit is stored in the storage unit by the determining unit. It is determined whether or not there is an abnormality in the droplet ejector by determining whether or not there is a predetermined value or more away from the natural period indicated by the reference natural period information. The suction recovery means is controlled to perform the suction recovery operation when it is determined that there is an abnormality, and the actuator is vibrated at the natural period measured by the measurement means simultaneously with the suction recovery operation. Is controlled.

As described above, according to the droplet discharge device of the first aspect, the pressure generation chamber filled with the liquid, the nozzle that discharges the droplet of the liquid in communication with the pressure generation chamber, and the vibration are vibrated. A droplet discharge head having a droplet ejector having an actuator for changing the volume of the pressure generation chamber to discharge the droplet from the nozzle; and a suction recovery means for performing a suction recovery operation on the nozzle; The reference natural period information indicating the natural period of the droplet ejector in a normal state is stored in advance by a storage unit, the natural period of the droplet ejector is measured at a predetermined timing, and the measured natural characteristic The liquid is determined by determining whether or not the period is a predetermined value or more away from the natural period indicated by the reference natural period information stored in the storage unit. It is determined whether or not there is an abnormality in the ejector, and when it is determined that there is an abnormality, the suction recovery means is controlled to perform the suction recovery operation, and at the same time as the suction recovery operation, the measured characteristic Since the actuator is controlled so as to vibrate at a period and not to vibrate at a period other than the natural period, the actuator can be vibrated at an accurate natural period. Can be removed.

  According to the present invention, as in the invention described in claim 2, the droplet discharge head includes a plurality of the droplet ejectors, and the measuring means measures the natural period of the droplet ejector. The determination unit determines whether or not the droplet ejector is abnormal for each droplet ejector, and the control unit determines that the control of the actuator is abnormal by the determination unit. It may be performed only for the actuator in the droplet ejector.

  In particular, according to the second aspect of the present invention, as in the third aspect of the present invention, the liquid droplet ejection head is disposed over the entire width of the recording medium to which the plurality of liquid droplet ejectors are ejected. It may be provided so as to correspond.

In the present invention, as in the invention described in claim 4 , the control means may control the vibration of the actuator by a drive signal constituted by a triangular wave.

Further, the present invention is preferable as defined in claim 5, the predetermined timing may be a timing when the non-ejection of droplets by the liquid droplet ejection heads. It should be noted that the timing when the liquid droplets are not ejected is the timing when the apparatus is in a standby state or the liquid droplets during image formation when applied when forming an image with liquid droplets are not ejected. Timing is included.

Further, in the present invention, the actuator may be a piezoelectric element as in the invention described in claim 6 .

As described above, according to the present invention, a pressure generating chamber filled with a liquid, a nozzle that communicates with the pressure generating chamber and discharges droplets of the liquid, and a volume of the pressure generating chamber by being vibrated. A liquid droplet ejection head having a liquid droplet ejector having an actuator for ejecting the liquid droplets from the nozzles by changing the pressure, and a suction recovery means for performing a suction recovery operation on the nozzles. Reference natural period information indicating the natural period of the droplet ejector is stored in advance by a storage unit, the natural period of the droplet ejector is measured at a predetermined timing, and the measured natural period is stored in the storage unit. An abnormality is detected in the droplet ejector by determining whether or not the natural period indicated by the stored reference natural period information is a predetermined value or more. Performed for determining whether or not there, controls the suction recovery means to perform the suction recovery operation when it is determined that there is an abnormality, vibrates at the natural period that the measured the suction recovery operation at the same time Since the actuator is controlled so as not to vibrate at a period other than the natural period, the actuator can be vibrated at an accurate natural period, and as a result, bubbles can be removed effectively in a short time. An excellent effect is obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the case where the present invention is applied to an ink jet recording apparatus that records an image by ejecting ink droplets will be described.

[First Embodiment]
FIG. 1 shows an ink jet recording apparatus 12 according to the present embodiment.

  As shown in the figure, a sheet feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and one sheet P stacked in the sheet feed tray 16 is picked up by a pickup roll 18. It can be taken out one by one. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22. Hereinafter, the “conveying direction” simply refers to the conveying direction of the paper P that is a recording medium, and the “upstream” and “downstream” refer to upstream and downstream in the conveying direction, respectively.

  Above the paper feed tray 16, an endless transport belt 28 stretched around a drive roll 24 and a driven roll 26 is disposed. A recording head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the recording head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image information are attached from the recording head array 30 in a state of facing the recording head array 30. The

  Then, by rotating the paper P while being held by the transport belt 28, the paper P can be passed through the discharge region SE a plurality of times, and so-called multipass image recording can be performed.

For example, the transport belt 28 is made of a semiconductive polyimide material (surface resistance value 10 ⁸ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹⁴ Ω · cm), thickness 75 μm, width 380 mm, circumference What was shape | molded in length 1000mm can be used. As the drive roll 24 and the driven roll 26, for example, a SUS roll having a diameter of 50 mm can be used.

  Further, the means for rotating the recording medium is not limited to the conveyance belt 28. For example, the recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roller formed in a cylindrical shape or a columnar shape and rotated. However, when the conveyor belt 28 is used as in the present embodiment, the flat portion 28F is formed, so that the recording head array 30 can be arranged corresponding to the flat portion 28F, which is preferable.

  In this embodiment, the recording head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and is yellow (Y) and magenta (M). , Cyan (C), and black (K), four ink jet recording heads 32 corresponding to each of the four colors are arranged along the transport direction, and a full color image can be recorded.

  The operation of each inkjet recording head 32 is controlled by a recording head controller 12E (see FIG. 5) described later. For example, the recording head controller 12 </ b> E determines an ink droplet ejection timing and an ink ejection port (nozzle) to be used according to the image information, and sends a drive signal to the inkjet recording head 32.

  The recording head array 30 may be stationary in a direction orthogonal to the transport direction. However, if the recording head array 30 is configured to move as necessary, an image with higher resolution can be obtained by multi-pass image recording. Or failure of the ink jet recording head 32 is not reflected in the recording result.

  Each ink jet recording head 32 according to the present embodiment is configured by connecting a plurality of printing units each composed of a plurality of droplet ejector 82 (see FIG. 6) groups in the longitudinal direction.

  Four maintenance units 34 corresponding to the respective ink jet recording heads 32 are arranged in the vicinity of the recording head array 30 (in this embodiment, both sides in the transport direction). When maintenance is performed on the inkjet recording head 32, the recording head array 30 moves upward as shown in FIG. 2, and the maintenance unit 34 moves to a gap formed between the conveyance belt 28 and the maintenance unit 34. Get in. And the predetermined maintenance operation | movement mentioned later is performed in the state which opposes the nozzle surface 32N (refer FIG. 3).

  In this embodiment, the four maintenance units 34 are divided into two sets of two, and are arranged on the upstream side and the downstream side of the recording head array 30 at the time of image recording by the recording head array 30, respectively. .

  On the other hand, as shown in detail in FIG. 3, a charging roll 36 connected to a power source 38 is disposed on the upstream side of the recording head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P can be charged and electrostatically attracted to the transport belt 28.

The charging roll 36 is formed with an elastic layer in which a conductivity imparting material is dispersed on a rod-like or pipe-like outer peripheral surface made of, for example, aluminum or stainless steel, and has a volume resistivity of 10 ⁶ to 10 ⁸ Ω · A roll of φ10 to 25 mm adjusted to about cm can be used. The elastic layer is made of a resin material such as urethane resin, thermoplastic elastomer, epichlorohydrin rubber, ethylene-propylene-diene copolymer rubber, silicone rubber, acrylonitrile-butadiene copolymer rubber, polynorbornene rubber, etc. A preferred material used in the above mixture is urethane foam resin. As the foamed urethane resin, those obtained by mixing and dispersing hollow bodies such as hollow glass beads and thermal expansion type microcapsules in urethane-based resin are desirably provided, and such a foamed urethane resin is desirable as a charging roll. It has low hardness elasticity, high contact stability with respect to the conveyor belt 28 is obtained, and nip formability is also improved. Furthermore, the surface of the elastic layer may be covered with a water-repellent skin layer having a thickness of 5 to 100 μm. In that case, change in characteristics (resistance) due to humidity change in the apparatus or adhesion of ink mist to the charged layer surface This is effective in suppressing (value change).

  As the power source 38, a DC power source is shown in FIG. 3, but an AC power source may be used as long as the paper P can be charged to a predetermined potential.

  A registration roll (not shown) is provided further upstream than the charging roll 36, and the paper P is aligned before reaching between the conveyance belt 28 and the charging roll 36.

  A peeling plate 40 is disposed on the downstream side of the recording head array 30, and the paper P can be peeled from the transport belt 28. As the peeling plate 40, for example, an aluminum plate having a thickness of 0.5 mm, a width of 330 mm, and a length of 100 mm can be used.

  The peeled paper P is transported by a plurality of discharge roller pairs 42 that constitute a discharge path 44 on the downstream side of the peeling plate 40, and is discharged to a paper discharge tray 46 provided on the top of the housing 14.

  Below the peeling plate 40, a cleaning roll 48 capable of sandwiching the conveying belt 28 with the driving roll 24 is disposed, and the surface of the conveying belt 28 is cleaned.

  A reversing path 52 composed of a plurality of reversing roller pairs 50 is provided between the paper feed tray 16 and the conveying belt 28, and the sheet P on which an image is recorded on one side is reversed and held on the conveying belt 28. By doing so, it is possible to easily record images on both sides of the paper P.

  Between the conveyance belt 28 and the paper discharge tray 46, an ink tank 54 for storing each of the four color inks is provided. The ink in the ink tank 54 is supplied to the recording head array 30 through an ink supply pipe (not shown). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink can be used.

  Next, the configuration of the ink jet recording head 32 and the maintenance unit 34 according to the present embodiment will be described in detail with reference to FIG.

  As shown in the figure, the maintenance unit 34 includes, for each printing unit 64, a cap 70 that closes the nozzle group, and a negative pressure accumulation tank 76 that is connected to the cap 70 via a pipe 74. A valve 72 is connected to the middle of the pipe 74.

  Further, the negative pressure accumulation tank 76 is connected to the waste ink tank 80 through a pipe 81, and a suction pump 78 is connected to the middle part of the pipe 81. The cap 70, the valve 72, the negative pressure accumulation tank 76, and the like are moved in the longitudinal direction of the ink jet recording head 32 (arrows shown in the figure) by moving means (not shown) so that the suction recovery operation (maintenance) can be performed for each printing unit 64. It is possible to move in a direction perpendicular to the traveling direction of the conveyor belt 28.

  Each ink jet recording head 32 has a branch portion 60 to which ink is supplied via a supply pipe 66 serving as a common flow path from each ink tank 54, and a plurality of individual flow paths 62 from the branch portion 60. The ink is branched and supplied to a plurality (four in the figure) of printing units 64 via the.

  Next, with reference to FIG. 5, the configuration of the main part of the electrical system of the inkjet recording apparatus 12 according to the present embodiment will be described.

  As shown in the figure, the inkjet recording apparatus 12 according to the present embodiment includes a CPU (Central Processing Unit) 12A that controls the operation of the entire apparatus, a RAM 12B that is used as a work area when various programs are executed, and the like. A ROM 12C in which various programs, parameter information, and the like are stored in advance, and a non-volatile and rewritable memory 12D are provided. The ink jet recording apparatus 12 is electrically and mechanically connected with a recording head controller 12E that controls the operation of the ink jet recording head 32, a maintenance unit controller 12F that controls the operation of the maintenance unit 34, and an external device such as a personal computer. An external interface 12G is also provided.

  The CPU 12A, RAM 12B, ROM 12C, memory 12D, recording head controller 12E, maintenance unit controller 12F, and external interface 12G are electrically connected to each other via a system bus BUS.

  Therefore, the CPU 12A performs access to the RAM 12B, ROM 12C, and memory 12D, control of the operation of the recording head controller 12E and the maintenance unit controller 12F, and exchange of various information with the external device via the external interface 12G. Each can be done. In addition to the above configuration, the inkjet recording apparatus 12 according to the present embodiment operates a plurality of motors (not shown) that rotationally drive each part such as the pickup roll 18, the conveyance roller pair 20, and the drive roll 24. A number of electrical components such as a motor controller for controlling the power supply and a power supply device for applying a voltage to the charging roll 36 are included. However, in order to avoid complications, these descriptions are omitted.

  Next, with reference to FIG. 6, the configuration of the main parts of the electrical system of the inkjet recording head 32 and the recording head controller 12E will be described.

  As shown in the figure, the ink jet recording head 32 includes a pressure generating chamber 82A filled with ink from an ink tank 54 (see FIG. 1), and a nozzle 82B communicating with the pressure generating chamber 82A and discharging ink droplets. A droplet including a vibration plate 82C that is bonded to the upper surface of the pressure generation chamber 82A and can be deformed in a vertical direction, and a piezoelectric element 82D that is bonded to the upper surface of the vibration plate 82C corresponding to the pressure generation chamber 82A. Many ejectors 82 are provided. Note that, as described above, the inkjet recording head 32 according to the present embodiment is configured by connecting a plurality of printing units including a plurality of droplet ejector 82 groups in the longitudinal direction.

  An electric substrate (not shown) is bonded to the upper surface of each piezoelectric element 82D. Between the electric substrate and an adhesive (not shown) that bonds the piezoelectric element 82D to the vibration plate 82C (hereinafter referred to as “drive signal applying unit”). When the piezoelectric element 82D is vibrated by applying a driving signal to “)”, the vibration deformation of the vibration plate 82C occurs, and as a result, the volume of the pressure generating chamber 82A changes and ink droplets are ejected from the nozzle 82B. it can.

  On the other hand, as shown in the figure, the recording head controller 12E includes a drive signal generation unit 90 that generates the drive signal and the drive signal generated by the drive signal generation unit 90 as one of the drive signals of the droplet ejector 82. And a signal switching unit 92 that switches so as to selectively apply to the application unit.

  The recording head controller 12E also includes a voltage sensor 94 that detects a level of voltage applied to the piezoelectric element 82D (hereinafter referred to as “voltage value”), and a level of current that flows through the piezoelectric element 82D (hereinafter referred to as “current value”). And a current sensor 96 for detecting "." The drive signal generation unit 90 according to the present embodiment generates a triangular wave drive signal as shown in FIG. 7 as an example.

  The drive signal generation unit 90, the signal switching unit 92, the voltage sensor 94, and the current sensor 96 are electrically connected to the CPU 12A via the system bus BUS, and the CPU 12A includes the generation state of the drive signal by the drive signal generation unit 90 and The switching state by the signal switching unit 92 can be controlled, and the detection results by the voltage sensor 94 and the current sensor 96 can be grasped.

  By the way, in the inkjet recording apparatus 12 according to the present embodiment, a predetermined timing (here, a timing at which a user inputs an instruction to perform the suction recovery operation by the maintenance unit 34 during non-image recording). ), The natural period of each droplet ejector 82 is measured, it is determined whether or not there is an abnormal droplet ejector 82 based on the natural period, and if there is, the maintenance unit 34 performs a suction recovery operation. At the same time, a droplet ejector abnormality recovery function for driving the piezoelectric element 82D is mounted. For this reason, the memory 12D stores three types of tables: a normal ejector table TB1, a measurement result table TB2, and an abnormal ejector table TB3.

  As shown in FIG. 8, the normal ejector table TB1 according to the present embodiment includes information on an ejector number for specifying the droplet ejector 82 and information on the natural period of the corresponding droplet ejector 82 at the normal time. Each drop ejector 82 is stored.

  Further, as shown in FIG. 9, the measurement result table TB2 according to the present embodiment has an ejector number similar to that of the normal ejector table TB1, and is within a range predetermined for the piezoelectric element 82D of the corresponding droplet ejector 82. Each information of the measurement result by the voltage sensor 94 and the current sensor 96 when the frequency drive signal is applied is stored for each droplet ejector 82. As shown in the figure, in the inkjet recording apparatus 12 according to the present embodiment, a range of 1.0 (kHz) to 300.0 (kHz) is set as the frequency range of the predetermined drive signal. Applicable.

  Furthermore, as shown in FIG. 10, in the abnormal ejector table TB3 according to the present embodiment, each information of the ejector number similar to the normal ejector table TB1 and the natural period of the corresponding droplet ejector 82 is determined to be abnormal. Each droplet ejector 82 is stored.

  8 to 10, in order to avoid complications, the normal ejector table TB1, the measurement result table TB2, and the abnormal ejector table TB3 are shown corresponding to only one ink jet recording head 32. Actually, these tables are stored for each inkjet recording head 32.

  In the ink jet recording apparatus 12 of the present embodiment configured as described above, the paper P taken out from the paper feed tray 16 is transported to the transport belt 28 as described above. Then, it is pressed against the conveyor belt 28 by the charging roll 36 and is held by being attracted (contacted) to the conveyor belt 28 by the voltage applied from the charging roll 36. In this state, while the paper P passes through the ejection area SE by circulation of the transport belt, ink droplets are ejected from the recording head array 30 and an image is recorded on the paper P. When recording an image in only one pass, the paper P is peeled from the transport belt 28 by the peeling plate 40, transported by the discharge roller pair 42, and discharged to the paper discharge tray 46. On the other hand, when performing image recording by multi-pass, after the paper P is circulated until it reaches the required number of times and passed through the ejection region SE, the paper P is peeled off from the transport belt 28 by the peeling plate 40, The paper is conveyed by the discharge roller pair 42 and discharged to the paper discharge tray 46.

  On the other hand, when the inkjet recording head 32 is maintained, first, the inkjet recording head 32 is raised by a predetermined height, and the maintenance unit 34 is disposed between the conveyance belt 28 and the inkjet recording head 32 (see FIG. 2). ).

  Thereafter, each cap 70 is disposed opposite to the nozzle surface of one print unit 64 in each inkjet recording head 32, the valve 72 is opened, and the nozzle group in one print unit 64 is negatively charged by the negative pressure accumulation tank 76. The suction recovery operation is performed on The suction recovery operation is sequentially performed on all the printing units 64 while moving the cap 70, the valve 72, the negative pressure accumulation tank 76, and the like in the longitudinal direction of the ink jet recording head 32 by the moving means (not shown). Maintenance of the inkjet recording head 32 is completed.

  Next, with reference to FIG. 11, the operation of the ink jet recording apparatus 12 at the time of executing the droplet ejector abnormality recovery function particularly related to the present invention will be described in detail. FIG. 11 is a flowchart showing the flow of processing of an abnormality recovery processing program executed by the CPU 12A when executing the droplet ejector abnormality recovery function, and the program is stored in advance in a predetermined area of the memory 12D. Here, a case where the natural period when each droplet ejector 82 is normal is stored in advance in the normal ejector table TB1 will be described. In addition, here, in order to avoid complications, the description will be made as processing for only one ink jet recording head 32, but actually, the same processing is performed for all ink jet recording heads 32.

  In step 100 of the figure, initialization is performed to clear the stored contents of the measurement result table TB2 and the abnormal ejector table TB3, and in the next step 102, the measurement processing routine program shown in FIG. 12 is executed. FIG. 12 is a flowchart showing the flow of processing of the measurement processing routine program. This program is also stored in advance in a predetermined area of the memory 12D. The measurement processing routine program will be described below.

  First, in step 200, an initial frequency (here, 1.0 (kHz)) is substituted for the variable f, and in the next step 202, any one liquid provided in the inkjet recording head 32 to be processed. The drive signal generating unit 90 and the signal switching unit 92 are controlled so that a drive signal having a frequency assigned to the variable f is applied to the droplet ejector 82 (hereinafter referred to as “processing target ejector”).

  Since the drive signal having the frequency assigned to the variable f is applied to the piezoelectric element 82D of the processing target ejector by the above processing, the voltage value detected by the voltage sensor 94 in this state in the next step 204. The current value detected by the current sensor 96 is acquired, and in the next step 206, the acquired voltage value and current value are stored in the corresponding column of the measurement result table TB2.

  In the next step 208, it is determined whether or not the frequency assigned to the variable f has reached a predetermined end frequency (here, 300.0 (kHz)). If a negative determination is made, the process proceeds to step 210. Then, after incrementing the value of the variable f by a predetermined increment (here, 1.5 (kHz)), the process returns to the above step 202, and proceeds to step 212 when an affirmative determination is made. By repeating the above steps 202 to 210, the measurement result corresponding to the processing target ejector in the measurement result table TB2 shown in FIG. 9 is stored as an example.

  In step 212, based on the measurement result stored in the measurement result table TB2 by the above processing, each frequency of the drive signal (here, 1.0 (kHz), 2.5 (kHz),..., 300). The phase difference between the voltage value and the current value is derived every .0 (kHz), and the dip portion (instantaneous decrease portion) of the derived phase difference for each frequency is detected in the next step 214. In the inkjet recording apparatus 12 according to the present embodiment, the detection of the dip portion is smaller than a phase difference corresponding to the initial frequency by a predetermined value (here, a value corresponding to 5% of the phase difference), and However, the present invention is not limited to this. For example, a configuration in which a minimum point with the smallest phase difference is detected may be used.

  In the next step 216, the driving frequency corresponding to the dip portion detected by the processing in step 214 is read from the measurement result table TB2, and the natural period Fb corresponding to the processing target ejector is read from the normal ejector table TB1. In step 218, when the reciprocal of the read drive frequency is the natural period Fx, it is determined whether or not the absolute value of the difference between the natural period Fx and the natural period Fb is greater than or equal to a predetermined value. The processing target ejector assumes that bubbles are generated in the pressure generating chamber 82A and is in an abnormal state, and the process proceeds to step 220. In the inkjet recording apparatus 12 according to the present embodiment, a value corresponding to 10% of the natural period Fb is applied as the predetermined value, but it is needless to say that the value is not limited to this.

  In step 220, the ejector number of the processing target ejector and the natural period Fx are stored in association with each other in the abnormal ejector table TB3, and then the process proceeds to step 222. If a negative determination is made in step 218, the process proceeds to step 222 without executing the process in step 220.

  In Step 222, it is determined whether or not the processing of Step 200 to Step 220 has been completed for all the droplet ejectors 82 provided in the inkjet recording head 32 to be processed. Returning to step 200, when the determination is affirmative, the present measurement processing routine program is terminated.

  By executing the above measurement processing routine program, in the abnormal ejector table TB3, the natural period of the droplet ejector 82, which is estimated that bubbles are generated in the pressure generating chamber 82A, corresponds to the ejector number of the droplet ejector 82. It will be stored in the attached state.

  When the measurement processing routine program ends, the process proceeds to step 104 of the abnormality recovery processing program (see FIG. 11), and it is determined whether or not the ejector number is stored in the abnormality ejector table TB3. It is determined whether or not there is a droplet ejector 82 that has been determined to be abnormal in the program. If a negative determination is made, the abnormality recovery processing program is terminated. Transition.

  In step 106, all ejector numbers and natural periods are read from the abnormal ejector table TB3, and in the next step 108, the ejector numbers read in the above-mentioned step 106 among the print units 64 of the inkjet recording head 32 to be processed are set. The maintenance unit controller 12F is controlled so as to perform a suction recovery operation with respect to any printing unit 64 (hereinafter referred to as “processing target printing unit”) in which the corresponding droplet ejector 82 exists.

  At this time, a drive signal that can vibrate the piezoelectric element 82D of the droplet ejector 82 corresponding to the ejector number read in step 106, present in the processing target printing unit, with the natural period read together with the ejector number, The recording head controller 12E is controlled so that it is applied to the piezoelectric element 82D of the corresponding droplet ejector 82 only for a predetermined period (here, the entire period during which the suction recovery operation is performed). Here, there may be a plurality of droplet ejectors 82 corresponding to the ejector numbers read out in step 106 in the processing target printing unit. In this case, each piezoelectric element 82D of the plurality of droplet ejectors 82 has a plurality of droplet ejectors 82D. On the other hand, the drive signals that can be vibrated at the corresponding natural period are set one by one in a predetermined order (here, the order of smaller ejector numbers) for a predetermined period (here, the period during which the suction recovery operation is performed). The recording head controller 12E is controlled so as to be applied step by step) (period obtained by dividing by the number of droplet ejectors 82 to be applied).

  In the next step 110, the completion of the suction recovery operation for the processing target print unit is waited, and in the next step 112, all the print units in which the droplet ejector 82 corresponding to the ejector number read in step 106 is present. It is determined whether or not the suction recovery operation has ended for 64, and if a negative determination is made, the process returns to step 108, and when the determination is affirmative, the abnormality recovery processing program is ended. Note that when the processes of Step 108 to Step 112 are repeatedly executed, the print unit 64 that has not been processed until then is set as a process target print unit.

  As described in detail above, in the present embodiment, a pressure generation chamber filled with a liquid (here, ink) and a droplet (here, an ink droplet) of the liquid are ejected in communication with the pressure generation chamber. A liquid droplet ejection head having a liquid droplet ejector having a nozzle that ejects the liquid droplets from the nozzle by changing the volume of the pressure generating chamber by being vibrated, and the piezoelectric element 82D in this case. Here, the ink jet recording head 32) and a suction recovery means (in this case, the maintenance unit 34) for performing a suction recovery operation on the nozzles are provided, and a reference indicating the natural period of the droplet ejector in a normal state. The natural period information (here, the natural period information of the normal ejector table TB1) is stored by the storage means (here, the memory 12D). The natural period of the droplet ejector is measured at a predetermined timing, and the measured natural period is equal to or greater than a predetermined value from the natural period indicated by the reference natural period information stored in the storage unit. It is determined whether or not there is an abnormality in the droplet ejector by determining whether or not they are separated, and the suction recovery means is controlled to perform the suction recovery operation when it is determined that there is an abnormality At the same time, since the actuator is controlled to vibrate with the measured natural period simultaneously with the suction recovery operation, the actuator can be vibrated with an accurate natural period. Bubbles can be removed.

  In the present embodiment, the droplet discharge head includes a plurality of droplet ejectors, and the natural period is measured for each droplet ejector to determine whether or not there is an abnormality in the droplet ejector. Is determined for each droplet ejector, and the actuator is controlled only for the actuator in the droplet ejector that is determined to be abnormal.In a droplet discharge head having a plurality of droplet ejectors, Air bubbles can be efficiently removed.

  In particular, in the present embodiment, the droplet discharge head is provided so that the plurality of droplet ejectors correspond to the entire width of the recording medium that is the droplet discharge destination. Also in the droplet discharge head, bubbles can be effectively removed in a short time.

  Further, in the present embodiment, since the vibration of the actuator is controlled by a drive signal constituted by a triangular wave, it is possible to prevent the occurrence of a failure of a circuit to which the drive signal is input and the occurrence of noise. In addition, power consumption can be suppressed.

  In this embodiment, since the suction recovery operation is executed at the timing when the droplets are not ejected by the droplet ejection head, adverse effects on the quality of the recorded image can be avoided.

  Further, in the present embodiment, since the actuator is a piezoelectric element, bubbles can be effectively removed in a short time in a droplet discharge head using the piezoelectric element.

[Second Embodiment]
In the second embodiment, the piezoelectric element 82D is driven during the execution of the droplet ejector abnormality recovery function so as to sweep (sweep) within a predetermined period range including the measured natural period. An example will be described. Note that the configuration of the inkjet recording apparatus 12 according to the present embodiment is the same as that according to the first embodiment except for the essential configuration of the electrical system of the inkjet recording head 32 and the recording head controller 12E. First, the main configuration of the electrical system of the inkjet recording head 32 and the recording head controller 12E of the inkjet recording apparatus 12 according to the present embodiment will be described with reference to FIG. The same components as those in FIG. 6 in FIG. 13 are denoted by the same reference numerals as those in FIG.

  As shown in the figure, the inkjet recording head 32 and the recording head controller 12E according to this embodiment are not provided with a signal switching unit 92, and a voltage sensor 94 and a current sensor 96 are provided for each droplet ejector 82. Only the differences are different from those according to the first embodiment. Note that the drive signal generation unit 90 according to the second embodiment generates a drive signal that has a triangular wave as shown in FIG. 14 and whose frequency changes within a predetermined range as an example.

  The drive signal generator 90 and a plurality of (the number of droplet ejectors 82) voltage sensors 94 and current sensors 96 are electrically connected to the CPU 12A via the system bus BUS. The CPU 12A is driven by the drive signal generator 90. The generation state of the signal can be controlled, and the detection result by each voltage sensor 94 and current sensor 96 (the detection result of the voltage value of the voltage applied to each piezoelectric element 82D and the current value of the current flowing through each piezoelectric element 82D) ).

  Next, the action of the inkjet recording apparatus 12 according to the second embodiment at the time of executing the droplet ejector abnormality recovery function particularly related to the present invention will be described in detail with reference to FIG. In addition, the same step number as FIG. 11 is attached | subjected about the step which performs the process similar to FIG. 11 of the figure, and the description is abbreviate | omitted.

  In step 102 ', the measurement processing routine program shown in FIG. 16 is executed. FIG. 16 is a flowchart showing the flow of processing of the measurement processing routine program according to the second embodiment, and the measurement processing routine program will be described below.

  First, in step 300, the initial frequency (here, 1.0 (kHz)) is substituted for the variable f, and in the next step 302, all droplet ejectors provided in the inkjet recording head 32 to be processed. The drive signal generation unit 90 is controlled so that a drive signal having a frequency assigned to the variable f is applied to 82 (hereinafter referred to as “all ejectors”).

  Since the drive signal having the frequency assigned to the variable f is applied to the piezoelectric elements 82D of all the ejectors by the above processing, the voltage value detected by each voltage sensor 94 in this state in the next step 304. The current values detected by the current sensors 96 are acquired for all the ejectors, and in the next step 306, the acquired voltage values and current values for all the ejectors are stored in the corresponding columns of the measurement result table TB2.

  In the next step 308, it is determined whether or not the frequency assigned to the variable f has reached a predetermined end frequency (here, 300.0 (kHz)). If the determination is negative, the process proceeds to step 310. Then, after the value of the variable f is incremented by a predetermined increment (here, 1.5 (kHz)), the process returns to step 302, and when the determination is affirmative, the process proceeds to step 312. By repeating the steps 302 to 310, the measurement results corresponding to all the ejectors in the measurement result table TB2 shown in FIG. 9 are stored as an example.

  In step 312, each frequency of the drive signal (here, 1.0 (kHz), 2.5 (kHz),..., 300) based on the measurement result stored in the measurement result table TB2 by the above processing. The phase difference between the voltage value and the current value is derived for all the ejectors every .0 (kHz), and further, in the next step 314, the dip portion (instantaneous decrease portion) of the phase difference for each frequency of all the derived ejectors. ) Is detected. In the inkjet recording apparatus 12 according to the present embodiment, the detection of the dip portion is smaller than a phase difference corresponding to the initial frequency by a predetermined value (here, a value corresponding to 5% of the phase difference), and However, the present invention is not limited to this. For example, a configuration in which a minimum point with the smallest phase difference is detected may be used.

  In the next step 316, the driving frequency corresponding to the dip portions of all the ejectors detected by the processing in step 314 is read from the measurement result table TB2, and the natural period Fb corresponding to all the ejectors is read from the normal ejector table TB1, In the next step 318, the reciprocal of the read drive frequency is set as the natural period Fx, and it is determined whether or not there is a droplet ejector whose absolute value of the difference between the natural period Fx and the natural period Fb is greater than or equal to a predetermined value. If the determination is affirmative, the droplet ejector 82 determined to be present is regarded as being in an abnormal state due to bubbles generated in the pressure generating chamber 82A, and the process proceeds to step 320. In the inkjet recording apparatus 12 according to the present embodiment, a value corresponding to 10% of the natural period Fb is applied as the predetermined value, but it is needless to say that the value is not limited to this.

  In step 320, the ejector number of the droplet ejector 82 determined to be present in step 318 and the natural period Fx are stored in association with each other in the abnormal ejector table TB3, and then the present measurement processing routine program is terminated. If the determination in step 318 is negative, the measurement processing routine program is terminated without executing the processing in step 320.

  By executing the above measurement processing routine program, in the abnormal ejector table TB3, the natural period of the droplet ejector 82, which is estimated that bubbles are generated in the pressure generating chamber 82A, corresponds to the ejector number of the droplet ejector 82. It will be stored in the attached state.

  When the measurement process routine program is completed, the process proceeds to step 104 of the abnormality recovery process program (see FIG. 15), and then, in step 108 ′, the above-described print unit 64 of the inkjet recording head 32 to be processed. The maintenance unit controller 12F is controlled so as to perform a suction recovery operation for any printing unit 64 (“processing target printing unit”) in which the droplet ejector 82 corresponding to the ejector number read in step 106 exists.

  At this time, a predetermined period range (here, including a natural period in which the piezoelectric element 82D of the droplet ejector 82 corresponding to the ejector number read in step 106, which is present in the processing target printing unit) is read together with the ejector number. Then, a drive signal that can be oscillated so as to sweep (sweep) within a range of ± 5% around the natural period is applied to the piezoelectric element 82D of the corresponding droplet ejector 82 for a predetermined period (here, suction). The recording head controller 12E is controlled so that it is applied only during the entire recovery operation). Here, there may be a plurality of droplet ejectors 82 corresponding to the ejector numbers read out in step 106 in the processing target printing unit. In this case, each piezoelectric element 82D of the plurality of droplet ejectors 82 has a plurality of droplet ejectors 82D. On the other hand, drive signals that can be oscillated so as to sweep within a predetermined period range including the corresponding natural period one by one in a predetermined order (here, the order of smaller ejector numbers) for a predetermined period (here, The recording head controller 12E is controlled so that the period during which the suction recovery operation is performed is divided by the number of droplet ejectors 82 to which the drive signal is applied.

  As described above in detail, the second embodiment can provide the same effects as those of the first embodiment, and includes a natural period in which the control of the actuator (here, the piezoelectric element 82D) is measured in advance. Since the sweeping is performed within the predetermined cycle range, the bubbles can be removed more effectively.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such changes or improvements are added are also included in the technical scope of the present invention.

  Further, the above embodiments do not limit the invention according to the claims (claims), and all combinations of features described in the embodiments are not necessarily essential to the solution means of the invention. Absent. The embodiments described above include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in the above-described embodiment, the case where the timing for executing the abnormality recovery processing program is set to the timing when the user inputs an instruction for instructing the execution of the suction recovery operation by the maintenance unit 34 has been described. For example, the timing at which the inkjet recording apparatus 12 is in a standby state, the timing at which ink droplets are not ejected when an image is recorded by the inkjet recording head 32, or the like is used. It can also be in the form. Also in this case, the same effect as the above embodiment can be obtained.

  In the above-described embodiment, the case where a configuration in which a plurality of printing units including a plurality of droplet ejector groups are connected in the longitudinal direction is applied as the inkjet recording head 32 has been described. For example, a configuration in which a plurality of droplet ejectors are arranged directly on the main body of the inkjet recording head 32 may be applied. Also in this case, the same effect as the above embodiment can be obtained.

  In the above embodiment, the case where only the droplet ejector 82 determined to be abnormal is vibrated with the natural period has been described. However, the present invention is not limited to this, for example, abnormal. In addition to the droplet ejector 82 determined to be present, the droplet ejector 82 determined to be normal may be vibrated. Also in this case, the same effect as the above embodiment can be obtained.

  In the first embodiment, a case where one voltage sensor 94 and one current sensor 96 are provided and the voltage value and the current value related to the piezoelectric element 82D of each droplet ejector 82 are sequentially measured for each piezoelectric element 82D will be described. In the second embodiment, one voltage sensor 94 and one current sensor 96 are provided for each droplet ejector 82, and the voltage value and the current value related to the piezoelectric element 82D of each droplet ejector 82 are measured simultaneously. Although described above, the present invention is not limited to this, and a combination of these forms, for example, a group for each of a plurality of droplet ejectors 82, one set for each group, a voltage sensor 94 and a current sensor 96. And a voltage value and a current value can be measured by switching drive signals within each group. Also in this case, the same effect as the above embodiment can be obtained.

  In the above-described embodiment, the case where the natural period is detected within a fixed driving frequency range (1.0 (kHz to 300.0 (kHz))) has been described, but the present invention is not limited thereto. For example, for each droplet ejector 82, a relatively narrow range centered on the natural period stored in the normal ejector table TB1 (for example, a range of ± 10 (kHz) centered on the natural period) In this case, the same effect as that of the above embodiment can be obtained.

  In the above embodiment, the case where the natural periods are stored in the normal ejector table TB1 and the abnormal ejector table TB3 has been described. However, the present invention is not limited to this, for example, instead of the natural period, It is also possible to store the natural frequency equal to the reciprocal of the natural period. Also in this case, the same effect as the above embodiment can be obtained.

  In the above embodiment, the case where the natural period of the droplet ejector 82 is derived based on the phase difference between the voltage value and the current value has been described. However, the present invention is not limited to this, and for example, the voltage A mode in which the natural period is derived by deriving and applying the dip portion of the impedance in the same manner as the dip portion of the phase difference in each of the above embodiments based on the impedance obtained by dividing the value by the current value It can also be. Also in this case, the same effect as the above embodiment can be obtained.

  In the above embodiment, the case where a triangular wave is applied as the drive signal has been described. However, the present invention is not limited to this, and for example, a sine wave or a rectangular wave may be applied. Also in this case, the same effect as the above embodiment can be obtained.

  In addition, the configurations (see FIGS. 1 to 7, 13, and 14) of the inkjet recording device 12 and the inkjet recording head 32 described in the above embodiment are merely examples, and the scope of the present invention is not deviated. Needless to say, it can be changed as appropriate.

  For example, the ink jet recording head is not limited to a long one (so-called FWA (Full Width Array) type), and may be a PWA (Partial Width Array) type ink jet recording head. Also in this case, the same effect as the above embodiment can be obtained.

  Moreover, the processing flow of each of the various programs described in the above embodiment (see FIGS. 11, 12, 15, and 16) is also an example, and can be appropriately changed without departing from the gist of the present invention. Needless to say.

  The data structures of the various tables described in the above embodiment (see FIGS. 8 to 10) are also examples, and it goes without saying that they can be changed as appropriate without departing from the gist of the present invention.

  Further, in the above embodiment, the case where ink is used as the droplet of the present invention has been described as an example. However, the present invention is not limited to this, and for example, a reaction liquid can be used instead of ink. . Specifically, since the image quality is further improved by mixing ink droplets and reaction droplets on the recording medium, the present invention can be applied in the same manner as described above when the reaction droplets are ejected by the nozzles. . In addition, the present invention can be applied to the application of the alignment film forming material of the liquid crystal display element, the application of the flux, the application of the adhesive, the application of the wiring material of the printed circuit board, and the like by the inkjet method.

It is a front sectional view showing the configuration of the ink jet recording apparatus according to the embodiment in the image recording state. It is a front sectional view showing the configuration of the ink jet recording apparatus according to the embodiment in a maintenance state. FIG. 2 is a conceptual front view showing a configuration of a conveyance belt and its vicinity of the ink jet recording apparatus according to the embodiment. It is the schematic which shows the structure of the inkjet recording head and maintenance unit which concern on embodiment. 1 is a block diagram illustrating a main configuration of an electric system of an ink jet recording apparatus according to an embodiment. FIG. 2 is a block diagram illustrating a main configuration of an electric system of the ink jet recording head and the recording head controller according to the first embodiment. It is a wave form diagram which shows the waveform of the drive signal which concerns on 1st Embodiment. It is a schematic diagram which shows an example of the data structure of the normal ejector table which concerns on embodiment. It is a schematic diagram which shows an example of the data structure of the measurement result table which concerns on embodiment. It is a schematic diagram which shows an example of the data structure of the abnormal ejector table which concerns on embodiment. It is a flowchart which shows the flow of a process of the abnormality recovery process program which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the measurement process routine program which concerns on 1st Embodiment. It is a block diagram which shows the principal part structure of the electric system of the inkjet recording head and recording head controller which concern on 2nd Embodiment. It is a wave form diagram which shows the waveform of the drive signal which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the abnormality recovery process program which concerns on 2nd Embodiment. It is a flowchart which shows the flow of a process of the measurement process routine program which concerns on 2nd Embodiment. It is a graph with which it uses for description of the problem of a prior art. It is another graph with which it uses for description of the problem of a prior art.

Explanation of symbols

12 Inkjet recording apparatus 12A CPU (measuring means, determination means, control means)
12D memory (storage means)
12E recording head controller 12F maintenance unit controller 32 ink jet recording head (droplet discharge head)
34 Maintenance unit (suction recovery means)
82 Droplet ejector 82A Pressure generating chamber 82B Nozzle 82C Diaphragm 82D Piezoelectric element (actuator)
90 drive signal generation unit 92 signal switching unit 94 voltage sensor 96 current sensor

Claims (6)

A pressure generating chamber filled with a liquid, a nozzle that communicates with the pressure generating chamber to discharge a droplet of the liquid, and a volume of the pressure generating chamber is changed by vibration to change the droplet from the nozzle. A droplet discharge head including a droplet ejector having an actuator to be discharged;
Suction recovery means for performing a suction recovery operation on the nozzle;
Storage means in which reference natural period information indicating the natural period of the droplet ejector at normal time is stored in advance;
Measuring means for measuring the natural period of the droplet ejector at a predetermined timing;
The droplet ejector is abnormal by determining whether or not the natural period measured by the measuring unit is more than a predetermined value from the natural period indicated by the reference natural period information stored in the storage unit Determining means for determining whether or not,
Controlling the suction recovery means to perform the suction recovery operation when the determination means determines that there is an abnormality, and vibrates in the natural period measured by the measurement means simultaneously with the suction recovery operation , Control means for controlling the actuator so as not to vibrate in a period other than the natural period ;
A droplet discharge device comprising: The droplet discharge head is provided with a plurality of the droplet ejectors,
The measurement means performs the measurement of the natural period for each droplet ejector,
The determination means determines whether or not there is an abnormality in the droplet ejector for each droplet ejector,
The droplet discharge device according to claim 1, wherein the control unit controls the actuator only for an actuator in a droplet ejector that is determined to be abnormal by the determination unit. The droplet ejection apparatus according to claim 2, wherein the droplet ejection head is provided so that the plurality of droplet ejectors correspond to the entire width of the recording medium to which the droplets are ejected. The control means, the droplet ejection apparatus according to any one of claims 1 to 3 carried out by the drive signal constituted by a triangular wave control of vibration of the actuator. The droplet ejection apparatus according to any one of the claims 1 to 4 to a predetermined timing to the timing at the time of non-ejection of droplets by the liquid droplet ejection heads. The droplet ejection apparatus according to any one of claims 1 to 5 and the piezoelectric element the actuator.