Patent Publication Number: US-11020961-B2

Title: Control method of liquid ejection apparatus

Description:
The present application is based on, and claims priority from JP Application Serial Number 2018-211983, filed Nov. 12, 2018, the disclosure of which is hereby incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to, for example, a control method of a liquid ejection apparatus provided with a liquid ejection head such as an ink jet recording head which ejects a liquid from a nozzle, and particularly to a control method of the liquid ejection apparatus after a liquid ejection operation is completed. 
     2. Related Art 
     A liquid ejection head is configured to receive supply of a liquid from a liquid storage member and eject the liquid from a nozzle by driving a pressure generating element such as a piezoelectric element or a heating element. In a liquid ejection apparatus provided with the liquid ejection head, for example, after a liquid ejection operation according to an operation instruction related to printing and recording of an image on a medium, predetermined control (hereinafter referred to as a sequence) is performed before a standby state, which continues until a next operation instruction is received, or before power of the liquid ejection apparatus is turned off. In this sequence, in order to cause a nozzle formation surface, on which nozzles of the liquid ejection head are formed, to face a cap which can seal the nozzle formation surface, an operation of moving the liquid ejection head and the cap relative to each other, a detection operation of detecting a nozzle from which a liquid is not normally ejected (for example, refer to JP-A-2016-020088), and the like are performed. In addition, in the related art, before the detection operation, a so-called idle ejection operation is performed in which a liquid is ejected (in other words, thrown away) from the nozzle in a state where the nozzle formation surface of the liquid ejection head and the above-described cap are faced each other in order to enhance detection accuracy. Since the nozzles of the liquid ejection head are exposed to the atmosphere while such a sequence is performed, in order to prevent the nozzle from being blocked by a thickened liquid, a vibration operation is performed in which the liquid in the nozzle is vibrated and agitated to such an extent that the liquid is not ejected (for example, refer to JP-A-2005-305869). 
     When the vibration operation is continuously performed, since the thickening of the liquid proceeds, it is necessary to discharge the thickened liquid before the next operation instruction is received and the liquid ejection operation is performed, after the above sequence is performed. As an operation of discharging the thickened liquid, the above idle ejection operation or a cleaning operation is performed in which a flow at a flow velocity higher than that in the idle ejection operation is generated in a liquid flow path in the liquid ejection head, and the liquid is discharged from the nozzle. When the vibration operation is performed for a longer period of time, since the thickening of the liquid further proceeds, it is necessary to increase the amount of the liquid to be discharged in the discharge operation by that amount. 
     SUMMARY 
     According to an aspect of the present disclosure, there is provided a control method of a liquid ejection apparatus including a liquid ejection head which has a nozzle formation surface on which a nozzle ejecting a liquid is formed, and a pressure generating element generating a pressure for ejecting the liquid from the nozzle, and performs a liquid ejection operation of ejecting the liquid onto a medium from the nozzle by driving the pressure generating element, an applying circuit which applies a drive waveform driving the pressure generating element to the pressure generating element, a cap configured to seal the nozzle formation surface, and an ejection failure detection portion which performs a detection operation of detecting ejection failure of the nozzle based on a residual vibration of the pressure generating element after applying the drive waveform to the pressure generating element by the applying circuit, the control method including starting a vibration operation of continuously applying the drive waveform for vibrating the liquid in the nozzle to the pressure generating element, after the liquid ejection operation is completed, starting the detection operation before a relative moving operation of relatively moving the liquid ejection head and the cap so as to face each other is completed, and stopping the vibration operation after the detection operation. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view illustrating a configuration of an embodiment of a liquid ejection apparatus. 
         FIG. 2  is a side view illustrating the configuration of the embodiment of the liquid ejection apparatus. 
         FIG. 3  is a side view illustrating the configuration of the embodiment of the liquid ejection apparatus. 
         FIG. 4  is a sectional view illustrating a configuration of an embodiment of a head unit. 
         FIG. 5  is a block diagram illustrating an electrical configuration of the liquid ejection apparatus. 
         FIG. 6  is a waveform diagram for describing an example of a drive signal. 
         FIG. 7  is a waveform diagram for describing an example of a first vibration drive pulse. 
         FIG. 8  is a waveform diagram for describing an example of a non-printing vibration drive signal. 
         FIG. 9  is a waveform diagram for describing an example of a second vibration drive pulse. 
         FIG. 10  is a flowchart illustrating a sequence in the related art, which is performed after a printing operation is completed. 
         FIG. 11  is a flowchart illustrating a sequence according to the present disclosure, which is performed after a printing operation is completed. 
         FIG. 12  is a front view illustrating a configuration of a liquid ejection apparatus according to a second embodiment. 
         FIG. 13  is a front view illustrating the configuration of the liquid ejection apparatus according to the second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Hereinafter, an embodiment for implementing the present disclosure will be described with reference to the attached drawings. In the embodiment described below, various limitations are given as preferable specific examples of the present disclosure; however, the scope of the present disclosure is not limited to these embodiments unless specifically stated to limit the present disclosure in the following description. In addition, the following description will be made by taking an ink jet printer equipped with an ink jet recording head (hereinafter, recording head) which is a type of a liquid ejection head  3 , as an example of a liquid ejection apparatus  1 . 
       FIGS. 1 to 3  are side views each illustrating the configuration of an embodiment of the liquid ejection apparatus  1 .  FIG. 1  illustrates a state where a printing operation as an example of a liquid ejection operation is performed on a medium  2 .  FIG. 2  illustrates a state where a support body  5  is retreated, and a nozzle formation surface of the liquid ejection head  3  and a cap  35  of a maintenance unit  6  are moved relative to each other after the printing operation is completed.  FIG. 3  illustrates a state where the nozzle formation surface of the liquid ejection head  3  and the cap  35  of the maintenance unit  6  are disposed to face each other. 
     The liquid ejection apparatus  1  in the present embodiment is an apparatus which ejects a liquid ink (a type of liquid in the present disclosure) from a nozzle  14  (refer to  FIG. 4 ) of the liquid ejection head  3  on a surface of the medium  2  such as recording paper, cloth, or resin film to record an image, a text, and the like. The liquid ejection apparatus  1  is provided with a transport mechanism  4  for transporting the medium  2 , the liquid ejection head  3 , the support body  5 , the maintenance unit,  6  and the like. 
     As the liquid ejection head  3  in the present embodiment, a so-called line-type liquid ejection head is adopted in which a plurality of head units  7  to be described later are arranged in a direction intersecting (orthogonal to in this embodiment) a transport direction of the medium  2 , and the entire length of a nozzle group formed by the plurality of head units  7  corresponds to the maximum recording width of the medium  2 . An ink is supplied to the liquid ejection head  3  from an ink cartridge  13  (refer to  FIG. 5 ) which is a liquid storage member storing the ink which is a type of a liquid. A configuration in which the ink cartridge  13  is attached to an upper surface of the liquid ejection head  3  can also be adopted. In addition, as the liquid storage member, an ink tank provided with an inlet capable of refilling the ink tank with the ink from an ink bottle storing the ink may be adopted. 
       FIG. 4  is a sectional view for describing an example of the configuration of the head unit  7  provided in the liquid ejection head  3 . In the head unit  7  in the present embodiment, a plurality of constituent members such as a nozzle plate  8 , a communication plate  9 , an actuator substrate  10 , a compliance substrate  11 , and a case  12  are stacked and joined by an adhesive or the like to be unitized. 
     The actuator substrate  10  in the present embodiment includes a plurality of pressure chambers  15  communicating with the respective nozzles  14  formed in the nozzle plate  8 , and a plurality of piezoelectric elements  16  that are pressure generating elements which cause pressure fluctuation in the ink in each of the pressure chambers  15 . A diaphragm  17  is provided between the pressure chamber  15  and the piezoelectric element  16 , and an upper opening of the pressure chamber  15  is sealed by the diaphragm  17  to partition off a part of the pressure chamber  15 . The respective piezoelectric elements  16  are stacked in regions corresponding to the pressure chambers  15  on the diaphragm  17 . The piezoelectric element  16  in the present embodiment is, for example, formed by sequentially stacking a lower electrode layer, a piezoelectric layer, and an upper electrode layer (none is illustrated) on the diaphragm  17 . The piezoelectric element  16  configured in such a manner is bent and deformed when an electric field corresponding to the potential difference between both the electrodes is applied between the lower electrode layer and the upper electrode layer. 
     To a lower surface of the actuator substrate  10 , the communication plate  9  having an area larger than that of the actuator substrate  10  in plan view as viewed from a substrate stacking direction is joined. The communication plate  9  in the present embodiment includes a nozzle communication port  18  for communicating the pressure chamber  15  with the nozzle  14 , a common liquid chamber  20  commonly provided to each of the pressure chambers  15 , and an individual communication port  19  for communicating the common liquid chamber  20  with the pressure chamber  15 . The common liquid chamber  20  is a space extending along a direction where the nozzles  14  are disposed in parallel. In the present embodiment, two common liquid chambers  20  are formed corresponding to the respective rows of two nozzles  14  provided in the nozzle plate  8 . A plurality of individual communication ports  19  are formed in a nozzle row direction corresponding to each of the pressure chambers  15 . The individual communication port  19  communicates with an end portion of the pressure chamber  15  opposite to a portion communicating with the nozzle communication port  18 . 
     The nozzle plate  8  in which nozzles  14  are formed is joined to a substantially central portion of the lower surface of the communication plate  9  described above. The nozzle plate  8  in the present embodiment is a plate member having an outer shape smaller than the communication plate  9  in plan view. The nozzle plate  8  is joined to the lower surface of the communication plate  9  with an adhesive or the like in a state where the nozzle communication port  18  and the nozzles  14  communicate with each other, at a position outside the openings of the common liquid chambers  20 , in a region where the nozzle communication ports  18  are opened. In the nozzle plate  8  in the present embodiment, a total of two nozzle rows in which the nozzles  14  are arranged are formed. In addition, to the lower surface of the communication plate  9 , the compliance substrate  11  is joined at a position outside the nozzle plate  8 . The compliance substrate  11  seals the opening of the common liquid chamber  20  on the lower surface of the communication plate  9  in a state where the compliance substrate  11  is positioned and joined to the lower surface of the communication plate  9 . The compliance substrate  11  has a function of alleviating pressure fluctuations in an ink flow path, particularly in the common liquid chamber  20 . 
     The actuator substrate  10  and the communication plate  9  are fixed to the case  12 . Inside the case  12 , an introduction liquid chamber  21  communicating with the common liquid chamber  20  of the communication plate  9  is formed on both sides of the actuator substrate  10 . In addition, on the upper surface of the case  12 , introduction ports  22  communicating with the respective introduced liquid chambers  21  are opened. The ink sent from the ink cartridge  13  is introduced into the introduction port  22 , the introduction liquid chamber  21 , and the common liquid chamber  20 , and is supplied from the common liquid chamber  20  to each of the pressure chambers  15  through the individual communication port  19 . In the head unit  7  configured as described above, the piezoelectric element  16  is driven in a state where inside the flow path from the introduction liquid chamber  21  to the nozzle  14  through the common liquid chamber  20  and the pressure chamber  15  is filled with the ink. Therefore, pressure fluctuation occurs in the ink in the pressure chamber  15 , and the pressure fluctuation (in other words, pressure vibration) causes the ink to be ejected from a certain nozzle  14 . The liquid ejection head  3  and the head unit  7  are not limited to the illustrated configuration, and various known configurations may be adopted. 
     The transport mechanism  4  is a mechanism that transports the medium  2  from a medium supply portion (not illustrated) to a discharge side by passing the medium  2  between the liquid ejection head  3  and the support body  5 . The transport mechanism  4  in the present embodiment also includes the support body  5 . The support body  5  transports the medium  2  to the downstream in the transport direction by the movement of a transport belt  25  bridged by a pair of rollers  24   a  and  24   b  disposed in parallel with a space in the transport direction of the medium  2 . In the present embodiment, the roller  24   a  disposed upstream in the transport direction is a drive roller  24   a  rotated by a drive source (not illustrated), and the roller  24   b  disposed downstream in the transport direction is a driven roller  24   b  rotated according to the rotation of the transport belt  25 . In addition, the support body  5  supports a printing surface of the medium  2 , that is, a surface opposite to a surface on which the ink ejected from the nozzle  14  lands during the printing operation by the liquid ejection head  3 . The printing surface of the medium  2  supported by the support body  5  faces the nozzle formation surface on which the nozzles  14  of the liquid ejection head  3  are formed, and recording is performed on the printing surface of the medium  2  by ejecting the ink from a certain nozzle  14 . In addition, the support body  5  defines a distance (in other words, gap) between the printing surface of the medium  2  and a head surface of the head unit  7  by supporting the medium  2  from below. The support body  5  is configured to be movable between a first position at which the support body  5  faces the nozzle formation surface of the liquid ejection head  3  (refer to  FIG. 1 ) and a second position deviated from the first position (refer to  FIGS. 2 and 3 ) by a support body moving mechanism  28 . 
     The support body moving mechanism  28  is provided with a first arm  29  and a second arm  30  rotatably coupled to each other. An end portion of the first arm  29  opposite to the second arm  30  is swingably attached to the support body  5 . In addition, an end portion of the second arm  30  opposite to the first arm  29  is coupled to a swing shaft  31 . A swing gear  32  is attached to the swing shaft  31 . The swing gear  32  rotates along with a drive gear  33  driven by a drive motor (not illustrated). The swing shaft  31  is rotated by the rotation of the swing gear  32 , and accordingly, the second arm  30  coupled to the swing shaft  31  is swung. As illustrated in  FIG. 1 , in the state where the support body  5  is disposed at the first position, under the control of a control circuit  17  described later, when the drive motor is driven and the swing gear  32  is rotated clockwise in the figure, the second arm  30  is also swung in the clockwise direction. The first arm  29  swings in the counterclockwise direction about a coupling portion with the second arm  30  as a swing center by the second arm  30  swinging in the clockwise direction. Accordingly, the support body  5  swings in the counterclockwise direction with the drive roller  24   a  as a swing fulcrum. As a result, as illustrated in  FIG. 2 , the driven roller  24   b  moves below the drive roller  24   a , and the support body  5  is retreated to the second position deviated from the first position. In addition, the swing gear  32  is swung in the counterclockwise direction in the state where the support body  5  is retreated to the second position. Therefore, the support body  5  swings in the clockwise direction about the drive roller  24   a  as a swing center, and the support body  5  moves from the second position to the first position. The support body  5  is not limited to the illustrated configuration, and various known configurations can be adopted. For example, the support body  5  may not have a structure for transporting the medium  2 . In addition, the support body moving mechanism  28  is not limited to the illustrated configuration, and various known configurations can be adopted. 
     As illustrated in  FIG. 3 , the maintenance unit  6  in the present embodiment is provided with the cap  35 , a moving base  36 , a link mechanism  37 , a guide member  38 , and a base member  39 . The base member  39  is a member serving as a bottom portion of the maintenance unit  6  and extends in the width direction of the medium  2 . A pair of guide members  38  is attached to both end portions of the base member  39  in the medium width direction. The moving base  36  is configured to be reciprocally movable in the transport direction of the medium  2  with respect to the base member  39  by a moving base drive portion (not illustrated). The link mechanisms  37  are attached to both end portions of the moving base  36  in the medium width direction. The link mechanism  37  is configured to include a first link member  37   a  and a second link member  37   b . The first link member  37   a  has a substantially triangular shape having a total of three vertexes. A portion corresponding to a first vertex of the first link member  37   a  is rotatably supported by the moving base  36 . In addition, a portion corresponding to a second vertex of the first link member  37   a  is rotatably coupled to the cap  35 . Furthermore, a cam follower  40  is provided at a portion corresponding to a third vertex of the first link member  37   a . One end of the second link member  37   b  is rotatably coupled to the moving base  36 , and the other end is rotatably coupled to the cap  35 . 
     A guide groove  41  is provided in the guide member  38 . The cam follower  40  of the link mechanism  37  is engaged with the guide groove  41 , and the guide groove  41  guides the cam follower  40  in the moving direction. The guide groove  41  in the present embodiment includes a first area  41   a  extending in the transport direction of the medium  2 , and a second area  41   b  gradually inclined downward toward the base member  39  and toward the upstream in the transport direction of the medium  2  while obliquely intersecting the first area  41   a.    
     The cap  35  is a member that seals the nozzle formation surface of the liquid ejection head  3 . The cap  35  is configured to be movable between a retreated position, as illustrated in  FIG. 1 , which is a position retreated within an area surrounded by the guide member  38 , and a maintenance position in which the cap  38  is lifted to the liquid ejection head  3  side from the guide member  38  and faces the nozzle formation surface of the liquid ejection head  3 . When the moving base  36  is moved from the downstream to the upstream in the transport direction of the medium  2  under the control of the control circuit  17  with the cap  35  in the retreated position as illustrated in  FIG. 1 , the cam follower  40  of the link mechanism  37  moves from the downstream toward the upstream in the transport direction while being guided by the first area  41   a  of the guide groove  41  as illustrated in  FIG. 2 . As a result, the link mechanism  37  and the cap  35  coupled to the moving base  36  move upstream in the transport direction. 
     When the moving base  36  further moves upstream in the transport direction, the cam follower  40  moves from the first area  41   a  to the second area  41   b  of the guide groove  41 . When the cam follower  40  moves from the first area  41   a  to the second area  41   b , the link mechanism  37  swings in the counterclockwise direction about the coupling portion with the moving base  36  as a fulcrum. As a result, the cap  35  is lifted toward the liquid ejection head  3 . When the moving base  36  is further moved upstream in the transport direction and the cam follower  40  moves near the end portion of the second area  41   b  upstream in the transport direction along the guide shape of the second area  41   b , the link mechanism  37  also further rotates in the counterclockwise direction. As a result, the cap  35  further ascends to face the nozzle formation surface of the liquid ejection head  3 . In an idle ejection operation, which is a type of maintenance operation, the cap  35  is moved to a position facing the nozzle formation surface with a space between the cap  35  and the nozzle formation surface of the liquid ejection head  3 . In this state, the control circuit  17  causes the idle ejection operation to be performed in which the ink is ejected from the nozzles  14  of the liquid ejection head  3  toward the cap  35 . As a result, the thickened ink in the nozzle  14  is discharged. The ink ejected into the cap  35  is discharged to a waste ink tank through a waste ink tube, neither of which is illustrated. A suction pump (not illustrated) is provided in the middle of the waste ink tube, and the waste ink in the cap  35  is discharged to the waste ink tank by driving the suction pump. 
     In addition, in a cleaning operation, which is a type of maintenance operation, the cap  35  further ascends from the above state to abut on the nozzle formation surface, and the nozzle formation surface is sealed so as to form a closed space in which the nozzles  14  are opened (in other words, capping state). In this state, the above-described suction pump is driven to make the closed space of the cap  35  negative pressure, so that the thickened ink, air bubbles, and the like are discharged with the ink from the nozzle  14  of the liquid ejection head  3  into the cap  35 . As the cleaning operation, there are two types of cleaning methods, a suction cleaning operation of suctioning the ink from the nozzle  14  by reducing the pressure outside the nozzle  14 , that is, inside the cap  35  in the capping state, and a pressurizing cleaning operation of discharging the ink from the nozzle  14  by pressurizing the liquid flow path on the upstream of the nozzle  14  with a pressurizing mechanism (not illustrated) different from the piezoelectric element  16 . In the present embodiment, the former suction cleaning is adopted. In any of the cleaning operations, a flow of ink having a higher flow velocity is generated in the liquid flow path inside the liquid ejection head  3  as compared with the above-described idle ejection operation, and more ink is discharged from the nozzle  14 . The mechanism for moving the liquid ejection head  3  and the cap  35  relative to each other is not limited to the illustrated configuration, and various known configurations may be adopted. In the present embodiment, by moving the support body  5  and the cap  35 , the cap  35  is moved to a position at which the support body  5  faces the nozzle formation surface of the liquid ejection head  3 ; however, for example, the liquid ejection head  3  may be moved to a position where the nozzle formation surface faces the cap  35 . Alternatively, by moving both the liquid ejection head  3  and the cap  35 , the nozzle formation surface may be moved to a position at with the nozzle formation surface faces the cap  35 . 
     In addition, as the pressurizing mechanism, for example, a configuration is adopted in which a diaphragm forming a portion of the flow path provided upstream of the pressure chamber  15  is bent and deformed by air pressurization to pressurize the ink in the flow path, in which a liquid storage member such as the ink cartridge  13  is pressurized, or the like. 
       FIG. 5  is a block diagram for describing an electrical configuration of the liquid ejection apparatus  1 . The liquid ejection apparatus  1  according to the present embodiment is provided with a sensor portion  44 , an ink residual amount detector  45 , and a printer controller  46  controlling these components, and the like, in addition to the transport mechanism  4 , the support body moving mechanism  28 , the maintenance unit  6 , and the liquid ejection head  3  described above. The sensor portion  44  includes a temperature sensor that detects a temperature (that is, environmental temperature), a humidity sensor that detects a humidity (that is, environmental humidity), and the like in an environment in which the liquid ejection apparatus  1  is installed. The sensor portion  44  detects the temperature and humidity inside the liquid ejection apparatus  1 , particularly, in the vicinity of the liquid ejection head  3 , and outputs the temperature and the humidity to the control circuit  43 . The ink residual amount detector  45  detects the amount of ink stored in the ink cartridge  13 , that is, the residual amount, and outputs the amount to the control circuit  43 . 
     The printer controller  46  is provided with the control circuit  43 , a drive signal generation circuit  47 , and the like. The control circuit  43  is an arithmetic processing unit for controlling the entire printer, and includes a CPU, a storage device, and the like (not illustrated). The control circuit  43  controls each part in the liquid ejection apparatus  1  according to a program or the like stored in the storage device. In addition, the control circuit  43  in the present embodiment generates ejection data for ejecting the ink from the nozzles  14  of the liquid ejection head  3  during the printing operation on the basis of the operation instruction and the print data received from the external device or the like. The ejection data is sent to a head control circuit  48  of the liquid ejection head  3 . Furthermore, the control circuit  43  also functions as a clocking unit, and can clock, for example, an elapsed time or the like from the time when the maintenance operation such as the idle ejection operation and the cleaning operation is completed. The drive signal generation circuit  47  generates an analog voltage signal on the basis of waveform data related to the waveform of a drive signal, and amplifies the voltage signal by an amplification circuit (not illustrated) to generate a drive signal. The drive signal generated by the drive signal generation circuit  47  is sent to the head control circuit  48  of the liquid ejection head  3 . The head control circuit  48  is a switch circuit that switches whether to apply a drive waveform (drive pulse to be described later) included in the drive signal from the drive signal generation circuit  47  to the piezoelectric element  16  on the basis of the ejection data from the control circuit  43 , and controls a printing operation (in other words, printing job) for ejecting the ink from the nozzles  14 . That is, the head control circuit  48  in the present embodiment functions as an applying circuit in the present disclosure. 
     The liquid ejection head  3  is provided with the head control circuit  48 , the piezoelectric element  16 , and an ejection failure detection portion  49 . The ejection failure detection portion  49  is a mechanism that detects ejection failure of each nozzle  14  of the liquid ejection head  3 . The ejection failure detection portion  49  in the present embodiment is configured to output, to the control circuit  43  as a detection signal, an electromotive force signal of the piezoelectric element  16  on the basis of residual vibration generated in the ink in the pressure chamber  15  when the piezoelectric element  16  is driven by the drive waveform. The control circuit  43  can perform a detection operation of detecting an abnormality in the ejection of the ink from the nozzle  14  on the basis of the detection signal output from the ejection failure detection portion  49 . When there is ejection failure, such as a case of nozzle missing where the ink is not ejected from the nozzle  14 , or the case in which the amount of ink and the flying speed (initial speed) are extremely reduced compared to the case in the normal nozzle  14  even if the ink is ejected from the nozzle  14 , the cycle of the detection signal, the attenuation ratio of the amplitude, and the like are different from those obtained in the normal state. Since detection of ejection abnormality based on the detection signal, that is, an electromotive force signal is well known, detailed description will not be repeated, and ejection abnormality of each nozzle  14  can be detected by such a detection method. The detection method for the ejection abnormality is not limited to one utilizing the electromotive force of the piezoelectric element  16  as illustrated, and for example, various known methods can be adopted, such as a method by optically detecting an ink droplet ejected from the nozzle  14 . 
       FIG. 6  is a waveform diagram for describing an example of a drive signal for a print operation (in other words, for liquid ejection operation), generated by the drive signal generation circuit  47 . The drive signal generation circuit  47  in the present embodiment repeatedly generates a first print drive signal COM 1  and a second print drive signal COM 2  at a predetermined print cycle T. An ejection drive pulse DP is generated within the print cycle T for the first print drive signal COM 1  in the present embodiment. A first vibration drive pulse VP 1  is generated within the print cycle T for the second print drive signal COM 2 . During the printing operation, the drive pulses DP and VP 1  are selectively applied to the respective piezoelectric elements  16 . That is, the ejection drive pulse DP is applied to the piezoelectric element  16  corresponding to the nozzle  14  which ejects the ink in the predetermined print cycle T, and the first vibration drive pulse VP 1  is applied to the piezoelectric element  16  corresponding to the nozzle  14  which does not eject the ink in the predetermined print cycle T. The configuration of the drive signal is not limited to the illustrated one, and various known aspects can be adopted. For example, a configuration may be adopted in which a plurality of types of ejection drive pulses different in the amount of ink ejected from the nozzles  14  are included in the print drive signal. 
       FIG. 7  is a diagram illustrating an example of a waveform of the first vibration drive pulse VP 1 . The first vibration drive pulse VP 1  is a drive waveform that causes the ink in the pressure chamber  15  and the nozzle  14  to be vibrated (that is, so-called slight minute vibration) by causing pressure fluctuation in the ink in the pressure chamber  15  to such an extent that the ink is not ejected from the nozzle  14 . By performing the vibration operation, that is, an in-printing vibration operation by the first vibration drive pulse VP 1 , the ink in the pressure chamber  15  and inside the nozzle  14  is agitated. That is, it is reduced that the ink remaining in the nozzle  14  continues to be in contact with the air for a long period of time. As a result, clogging of the nozzle  14  with the thickened ink is suppressed, and generation of ejection failure due to the thickened ink is suppressed. 
     The first vibration drive pulse VP 1  in the present embodiment has an inverted trapezoidal voltage waveform including a first expansion element p 1 , a first hold element p 2 , and a first contraction element p 3 . The first expansion element p 1  is a waveform element in which the potential drops from a reference potential VB to a first vibration potential Vv 1  lower than the reference potential VB. The first hold element p 2  is a waveform element that maintains the first vibration potential Vv 1 , which is a termination potential of the first expansion element p 1 , for a certain period of time. The first contraction element p 3  is a waveform element in which the potential ascends from the first vibration potential Vv 1  to the reference potential VB. When the first vibration drive pulse VP 1  is applied to the piezoelectric element  16 , first, the piezoelectric element  16  is bent to the outside of the pressure chamber  15  (in other words, side away from the nozzle plate  8 ) from the reference state (in other words, initial state) corresponding to the reference potential VB by the first expansion element p 1 , and the pressure chamber  15  expands from the reference volume corresponding to the reference potential VB to a first minute vibration expansion volume corresponding to the first vibration potential Vv 1 . The expanded state of the pressure chamber  15  is maintained throughout an application period of the first hold element p 2 . Subsequently, the piezoelectric element  16  is bent to the inside of the pressure chamber  15  (in other words, side approaching the nozzle plate  8 ) by the first contraction element p 3 , and the pressure chamber  15  returns from the first minute vibration expansion volume corresponding to the first vibration potential Vv 1  to the reference volume. As described above, due to the expansion of the pressure chamber  15  by the first expansion element p 1  and the contraction of the pressure chamber  15  by the first contraction element p 3 , pressure vibration occurs in the ink in the pressure chamber  15 , and thus the ink in the pressure chamber  15  and in the nozzle  14  is agitated. 
     In general, a minute vibration operation using the vibration drive pulse can be divided broadly into a so-called non-printing vibration operation performed in a state where the printing operation is not performed when the liquid ejection apparatus  1  is powered on, and the above-described in-printing vibration operation. In the former in-printing vibration operation, since the printing stability is emphasized, the inclination of the voltage or potential change of the entire vibration drive pulse is suppressed to be smaller, or the frequency applied to the piezoelectric element  16  (hereinafter referred to as application frequency) is suppressed to a lower level, and the residual vibration after the minute vibration operation is suppressed as low as possible. On the other hand, in the latter non-printing vibration operation, since the agitating effect is more important than the printing stability, the inclination of the voltage or potential change of the entire vibration drive pulse is set larger, or the application frequency is set higher, compared to the case in the in-printing vibration operation. 
       FIG. 8  is a waveform diagram for describing an example of a non-printing vibration drive signal COMv generated by the drive signal generation circuit  47 . The drive signal generation circuit  47  according to the present embodiment is configured to generate the non-printing vibration drive signal COMv during a period in which the printing operation is not performed, in addition to the first print drive signal COM 1  and the second print drive signal COM 2 . The non-printing vibration drive signal COMv is a drive signal for generating a second vibration drive pulse VP 2  (a type of drive waveform in the present disclosure). The drive signal generation circuit  47  repeatedly generates the non-printing vibration drive signal COMv at a predetermined drive cycle Tv in the non-printing vibration operation. The drive cycle Tv is shorter than the print cycle T of the print drive signals COM 1  and COM 2 , that is, the application frequency is set higher. 
       FIG. 9  is a diagram illustrating an example of a waveform of the second vibration drive pulse VP 2 . In the figure, the first vibration drive pulse VP 1  is indicated by a broken line for comparison. The second vibration drive pulse VP 2  is a drive pulse that causes the ink in the pressure chamber  15  and the nozzle  14  to be vibrated and agitated by causing pressure fluctuation in the ink in the pressure chamber  15  to such an extent that the ink is not ejected from the nozzle  14 . The second vibration drive pulse VP 2  in the present embodiment has a second expansion element p 4 , a second hold element p 5 , and a second contraction element p 6 . The second expansion element p 4  is a waveform element in which the potential drops from the reference potential VB to a second vibration potential Vv 2  lower than the reference potential VB and the first vibration potential Vv 1 . The second hold element p 5  is a waveform element that maintains the second vibration potential Vv 2 , which is a termination potential of the second expansion element p 4 , for a certain period of time. The second contraction element p 6  is a waveform element in which the potential ascends from the second vibration potential Vv 2  to the reference potential VB. 
     When the second vibration drive pulse VP 2  is applied to the piezoelectric element  16 , first, the piezoelectric element  16  is bent to the outside of the pressure chamber  15  from the reference state corresponding to the reference potential VB by the second expansion element p 4 , and the pressure chamber  15  expands from the reference volume corresponding to the reference potential VB to a second minute vibration expansion volume corresponding to the second vibration potential Vv 2 . The second minute vibration expansion volume is larger than the first minute vibration expansion volume. The expanded state of the pressure chamber  15  is maintained throughout an application period of the second hold element p 5 . Subsequently, the piezoelectric element  16  is bent to the inside of the pressure chamber  15  by the second contraction element p 6 , and the pressure chamber  15  returns from the second minute vibration expansion volume corresponding to the second vibration potential Vv 2  to the reference volume. As described above, due to the expansion of the pressure chamber  15  by the second expansion element p 4  and the contraction of the pressure chamber  15  by the second contraction element p 6 , pressure vibration occurs in the ink in the pressure chamber  15 , and the ink in the pressure chamber  15  and in the nozzle  14  is agitated. In the non-printing vibration operation, the second vibration drive pulse VP 2  is continuously applied to the piezoelectric element  16  at a drive cycle Tv shorter than that in the in-printing vibration operation, and thus the ink is vibrated and agitated. 
     Regarding the second vibration drive pulse VP 2  in the present embodiment, a second vibration drive voltage (that is, the potential difference between the reference potential VB and the second vibration potential Vv 2 ) V 2  which is a wave height of the second vibration drive pulse VP 2  is set larger than a first vibration drive voltage (that is, the potential difference between the reference potential VB and the first vibration potential Vv 1 ) V 1  which is a wave height of the first vibration drive pulse VP 1 . The inclinations (that is, the rate of change in potential per unit time) of the second expansion element p 4  and the second contraction element p 6 , which are waveform elements whose potentials change, are also set larger (that is, steeper) than the inclinations of the first expansion element p 1  and the first contraction element p 3  of the first vibration drive pulse VP 1 . These Parameters related to the second vibration drive pulse VP 2  are set so as to fall within a range where the ink is not ejected from the nozzles  14 . 
     The parameters related to the second vibration drive pulse VP 2  in the non-printing vibration operation may be changed according to any of the temperature and humidity detected by the sensor portion  44 , and the elapsed time from the last performed idle ejection operation or the cleaning operation, or a combination thereof. For example, as the temperature detected by the sensor portion  44  is higher, as the environmental humidity is lower, or as the elapsed time from the last performed idle ejection operation or cleaning operation is longer, the ink in the nozzle  14  is more thickened. Therefore, the wave height (first vibration drive voltage V 2 ) of the second vibration drive pulse VP 2  in the non-printing vibration operation may be set higher, or the application frequency of the second vibration drive pulse VP 2  to the piezoelectric element  16  may be set higher. As a result, the thickened ink in the nozzle  14  can be more significantly agitated. In addition, for example, as the temperature detected by the sensor portion  44  is lower, as the environmental humidity is higher, or as the elapsed time from the last performed idle ejection operation or the like is shorter, the progress of thickening of the ink in the nozzle  14  is slower. Therefore, the wave height of the second vibration drive pulse VP 2  in the non-printing vibration operation may be set lower, or the application frequency of the second vibration drive pulse VP 2  to the piezoelectric element  16  may be set lower. As a result, it is possible to suppress the progress of the thickening due to the non-printing vibration operation and the heat generation of the piezoelectric element  16 . In this case, in the non-printing vibration operation, the first vibration drive pulse VP 1  used in the in-printing vibration operation may be used instead of the second vibration drive pulse VP 2 . As described above, by changing the parameters related to the second vibration drive pulse VP 2 , it is possible to perform the more appropriate non-printing vibration operation according to the situation. 
     In such a non-printing vibration operation, as compared with the in-printing vibration operation, the ink in the pressure chamber  15  and in the nozzle  14  is more significantly agitated and the heat generation of the piezoelectric element  16  is also increased. Therefore, it also has the aspect that, when the non-printing vibration operation is continued for a longer period of time, the thickening of the ink proceeds to the pressure chamber  15  side. Therefore, it is necessary to discharge the thickened liquid before the printing operation is performed when receiving the next operation instruction, after the non-printing vibration operation. That is, the idle ejection operation or the cleaning operation is performed as the maintenance operation. When the in-printing vibration operation is performed for a longer time, it is necessary to increase the amount of ink discharged in the maintenance operation by that amount. In the liquid ejection apparatus  1  according to the present disclosure, the amount of ink discharged in the maintenance operation is reduced by devising the sequence after the end of the printing operation. Hereinafter, this point will be described. 
       FIG. 10  is a flow chart for describing a sequence in the related art (corresponding to a second sequence in the present disclosure) performed after a printing operation is completed. 
     First, a sequence after the end of the printing operation which is performed in the related art will be described. When a series of printing operations based on the operation instruction is completed (Step S 1 ), a non-printing vibration operation which is a vibration operation is started (Step S 2 ). That is, the head control circuit  48  starts agitation of the ink in the pressure chamber  15  and in the nozzle  14  by continuously applying the second vibration drive pulse VP 2  of the non-printing vibration drive signal COMv from the drive signal generation circuit  47  to each piezoelectric element  16  at the drive cycle Tv. In the following, the non-printing vibration operation is continued. Subsequently, a retreating operation of the support body  5  is performed (Step S 3 ). As described above, the control circuit  17  controls the support body moving mechanism  28  to retreat the support body  5  from the first position at which the support body  5  faces the nozzle formation surface of the liquid ejection head  3  to the second position. Next, a relative moving operation is performed in which the cap  35  and the nozzle formation surface of the liquid ejection head  3  face each other (Step S 4 ). That is, when the control circuit  17  controls the maintenance unit  6 , the cap  35  at the retreated position is pushed up toward the liquid ejection head  3  and disposed at a position facing the nozzle formation surface of the liquid ejection head  3 . In this state, the idle ejection operation is performed (Step S 5 ). As a result, the thickened ink in the vicinity of the nozzle  14  is discharged. 
     Subsequently, the control circuit  43  performs a detection operation of detecting abnormality in the ejection of the ink from the nozzle  14  on the basis of the electromotive force signal output from the ejection failure detection portion  49  (Step S 6 ). As the drive waveform applied to the piezoelectric element  16  in the detection operation, the second vibration drive pulse VP 2  in the non-printing vibration operation can be used, or a drive waveform dedicated for the detection operation can be used. When the ejection failure is detected as a result of the detection operation, for example, information on the nozzle  14  in which the ejection failure has been detected is stored in a storage portion or the like. In addition, the fact that the ejection failure has been detected may be displayed on a display device or the like to notify the user. If the operation of detecting the ejection failure is performed, the non-printing vibration operation is subsequently stopped (Step S 7 ). Thereafter, the nozzle formation surface is sealed by the cap  35 , and then a standby state is kept until an instruction such as a print job is received, or the power of the liquid ejection apparatus  1  is turned off. The idle ejection operation or the cleaning operation is performed as the maintenance operation before the next operation instruction is received from an external device or the like and the printing operation is performed. The thickened ink is discharged from each nozzle  14  during the above sequence, standby state, or power-off state. 
     In this sequence in the related art, since the non-printing vibration operation continues in the range from Step S 2  to Step S 4 , heat generation by driving the piezoelectric element  16  and thickening from the nozzle  14  to the pressure chamber  15  side progress during this time. In particular, in the configuration in which the retreating operation of the support body  5  and the relative moving operation to cause the nozzle formation surface and the cap  35  face each other are performed, the non-printing vibration operation is longer, and it is necessary to increase the amount of ink to be discharged in the idle ejection operation discharged in Step S 5 . In addition, since a non-printing minute vibration is continued after the idle ejection operation in Step S 5  before a non-printing minute vibration operation in Step S 7  is completed, it is necessary to increase the amount of ink to be discharged by that amount in the maintenance operation performed before the printing operation by receiving the next operation instruction. 
       FIG. 11  is a flowchart for describing a sequence (corresponding to a first sequence in the present disclosure) according to the present disclosure after the printing operation is completed. When a series of printing operations based on the operation instruction is completed (Step S 11 ), the non-printing vibration operation, which is the vibration operation, is started similar to the sequence in the related art (Step S 12 ). Subsequently, the operation of detecting ejection abnormality is performed for each nozzle  14  (Step S 13 ). Similarly to the sequence in the related art, when the ejection failure is detected as a result of the detection operation, for example, information on the nozzle  14  in which the ejection failure is detected is stored in the storage portion or the like. In addition, the fact that the ejection failure has been detected may be displayed on the display device or the like to notify the user. When the ejection failure is detected, the detection operation may be performed again after the idle ejection operation or the cleaning operation is performed. With this, the detection accuracy of the ejection failure in the detection operation can be further enhanced. After the detection operation, the non-printing vibration operation is stopped (Step S 14 ). That is, after the printing operation is completed and after the operation of detecting the ejection failure is performed, since the quality of each nozzle  14  in the ejection state is not questioned until the next operation instruction is received, it is not necessary to perform the non-printing vibration operation thereafter. Regarding the stop of the non-printing vibration operation after the detection operation, the non-printing vibration operation may be stopped sequentially from the nozzle  14  in which the detection operation has been completed, or it is also possible to stop the non-printing vibration operation after the detection operation of all the nozzles  14  is completed. The former can suppress useless non-printing vibration operation. 
     Next, the retreating operation of the support body  5  is performed (Step S 15 ). As described above, the control circuit  17  controls the support body moving mechanism  28  to move the support body  5  from the first position at which the support body  5  faces the nozzle formation surface of the liquid ejection head  3  to the second position. Subsequently, a relative moving operation is performed to cause the cap  35  and the nozzle formation surface of the liquid ejection head  3  face each other (Step S 16 ). That is, when the control circuit  17  controls the maintenance unit  6 , the cap  35  at the retreated position is pushed up toward the liquid ejection head  3  and disposed at a position at which the support body  5  faces the nozzle formation surface of the liquid ejection head  3 . In this state, the idle ejection operation is performed (Step S 17 ). As a result, it is possible to discharge the thickened ink by the non-printing vibration operation. Here, as described above, when the parameters related to the second vibration drive pulse VP 2  in the non-printing vibration operation are changed due to the environmental temperature or the like, the discharge amount of ink in the idle ejection operation may be changed accordingly. For example, when the wave height of the second vibration drive pulse VP 2  is set higher or the application frequency of the second vibration drive pulse VP 2  to the piezoelectric element  16  is set higher, since the thickening further proceeds, it is desirable to further increase the discharge amount of ink in the idle ejection operation. In addition, when the wave height of the second vibration drive pulse VP 2  is set lower, or the application frequency of the second vibration drive pulse VP 2  to the piezoelectric element  16  is set lower, since the progress of the thickening is relatively gentle, it is desirable to reduce the discharge amount of ink in the idle ejection operation. As a result, it is possible to further reduce the discharge amount of ink in the idle ejection operation. 
     Thereafter, the nozzle formation surface is sealed by the cap  35 , and then a standby state is kept until the next instruction such as a print job is received, or the power of the liquid ejection apparatus  1  is turned off. The idle ejection operation or the cleaning operation is performed as the maintenance operation before the next operation instruction is received from an external device or the like and the printing operation is performed, and the thickened ink is discharged from each nozzle  14 . 
     As described above, in the first sequence according to the present disclosure, the detection operation is started before the relative moving operation between the liquid ejection head  3  and the cap  35  is completed, more specifically, before the relative moving operation is started, and the non-printing vibration operation is stopped after the detection operation. Therefore, the range in which the non-printing vibration operation is continued is between Step S 12  and Step S 14 , and as compared with the case where the detection operation is performed after the second sequence, that is, the retreating operation, the relative moving operation, and idle ejection operation, the duration time of the non-printing vibration operation which is the vibration operation after the end of the liquid ejection operation is reduced. Therefore, it is possible to suppress the heat generation by driving the piezoelectric element  16  and the progress of thickening from the nozzle  14  to the pressure chamber  15  side. As a result, in the discharge operation of the thickened ink (for example, idle ejection operation or cleaning operation), the discharge amount of the ink required to discharge the thickened ink (that is, total amount of liquid discharged in the discharge operation) can be reduced. In particular, in a configuration in which a so-called line-type liquid ejection head is equipped as in the liquid ejection head  3  in the present embodiment, and the retreating operation of the support body  5  is performed after the printing operation is completed and before the relative moving operation, according to the first sequence of the present disclosure, since the detection operation is started before the retreating operation is completed, it is possible to more effectively reduce the duration time of the non-printing vibration operation. As a result, it is possible to suppress the heat generation and the progress of thickening due to driving the piezoelectric element  16 , and it is possible to further reduce the amount of ink discharged in the discharge operation (that is, maintenance operation). 
     Here, regarding the timing at which the operation of detecting the ejection failure is performed, in the present embodiment, although an example is described in which the operation of detecting the ejection failure is performed before the relative moving operation between the liquid ejection head  3  and the cap  35  is started, the present disclosure is not limited thereto before the relative moving operation is completed. For example, in a configuration in which the retreating operation of the support body  5  is not performed (liquid ejection apparatus such as a so-called serial printer described later), the detection operation may be started simultaneously when the relative moving operation between the liquid ejection head  3  and the cap  35  is started. That is, in this case, the detection operation and the relative moving operation are performed in parallel. Also in this case, compared with the case where the detection operation is performed after the relative moving operation, it is possible to reduce the time during which the non-printing vibration operation is continued. As a result, it is possible to reduce the amount of ink discharged in the discharge operation. In addition, by performing the detection operation and the relative moving operation in parallel, it is possible to reduce the processing time of the entire sequence after the printing operation is completed. 
     In addition, in the present embodiment, although an example is described in which the retreating operation of the support body  5  is performed before the relative moving operation between the liquid ejection head  3  and the cap  35 , and the operation of detecting the ejection failure is performed before the retreating operation is started, the present disclosure is not limited thereto before the retreating operation is completed. For example, the detection operation may be started simultaneously when the retreating operation is started. That is, in this case, the detection operation and the retreating operation are performed in parallel. Also in this case, compared with the case where the detection operation is performed after the retreating operation and the relative moving operation, it is possible to reduce the time during which the non-printing vibration operation is continued. As a result, by performing the detection operation and the retreating operation in parallel, it is possible to reduce the processing time of the entire sequence after the printing operation is completed. 
     Here, as the sequence after the printing operation is completed, the first sequence may not necessarily be performed, and the first sequence and the second sequence may be switched according to the situation. For example, in a situation where thickening is already progressed to such an extent that the nozzle  14  is blocked at the time of completion of the printing operation, since it is preferable to perform the non-printing vibration operation longer for agitation, the second sequence may be switched. In addition, for example, the first sequence and the second sequence may be switched according to the amount of ink in the ink cartridge  13  detected by the ink residual amount detector  45 . That is, when the amount of ink in the ink cartridge  13  is relatively large (for example, larger than a predetermined threshold value), since the amount of ink may be enough, the second sequence may be switched. In the second sequence, since the operation of detecting the ejection failure is performed after the idle ejection operation is performed, there is an advantage that the detection accuracy is higher compared to that of the first sequence. On the other hand, when the amount of ink in the ink cartridge  13  is relatively small (for example, less than a predetermined threshold), it is desirable to switch to the first sequence in order to suppress the progress of thickening of the ink as much as possible and to reduce the discharge amount of ink in the discharge operation. As a result, when the residual amount of ink in the ink cartridge  13  is small, the time in which the printing operation can be performed can be extended as much as possible. 
     The first sequence basically includes a sequence in which the vibration operation is started after the liquid ejection operation is completed, the detection operation is started before the relative moving operation is completed, and the vibration operation is stopped after the detection operation regardless of whether or not the relative moving operation is completed. The first sequence means that the detection operation is started before the retreating operation is completed when the retreating operation of the support body is started. In addition, the second sequence basically includes a sequence in which the vibration operation is started after the liquid ejection operation is completed, the detection operation is performed after the relative moving operation and the idle ejection operation are performed, and the vibration operation is stopped after the detection operation. The second sequence means that the detection operation is performed after the retreating operation, the relative moving operation, and the idle ejection operation are completed when the retreating operation of the support body is started. 
       FIGS. 12 and 13  are front views for describing the configuration of a liquid ejection apparatus  51  in the second embodiment. In  FIG. 12 , the liquid ejection apparatus  51  exemplified in the present embodiment is a so-called serial printer that performs printing while scanning a liquid ejection head  52  in the width direction of the medium. The liquid ejection head  52  in the present embodiment is attached to the bottom surface of a carriage  55  on which an ink cartridge  54 , which is a liquid storage member, is equipped. The carriage  55  is configured to be reciprocally movable along a guide rod  56  by a carriage movement mechanism (not illustrated). Similarly to the liquid ejection apparatus  1  of the first embodiment, the liquid ejection apparatus  51  in the present embodiment performs a printing operation which is a liquid ejection operation on the basis of an operation instruction received from an external device or the like. That is, a medium  53  is sequentially transported onto a platen  57  which is one aspect of the support body by a transport mechanism (not illustrated), and while relatively moving the liquid ejection head  52  in the width direction (main scanning direction) of the medium  53 , an ink, which is a type of liquid, is ejected from the nozzle of the liquid ejection head  52  and landed on the recording surface of the medium  53 , to record and print an image or the like. Although the platen  57  which is a support body in the present embodiment supports the medium  53 , the platen  57  does not have a structure for transporting the medium  53 , and the retreating operation is not performed. 
     Inside the liquid ejection apparatus  51 , a home position which is a standby position of the liquid ejection head  52  is set at a position deviated to one end side in the main scanning direction with respect to the platen  57  (right side in  FIGS. 12 and 13 ). A capping mechanism  59  is provided at this home position. The capping mechanism  59  includes, for example, a cap  60  (a type of sealing member) formed of an elastic member such as an elastomer, and is configured to be convertible into a state where the cap  60  is abutted against the nozzle formation surface of the liquid ejection head  52  on which the nozzles are formed, and sealed (capping state), or a retreated state separated from the nozzle formation surface. The capping mechanism  59  can perform the cleaning operation of forcibly discharging ink or the like from the nozzles by driving a suction pump (not illustrated) in a state where the nozzle formation surface of the liquid ejection head  52  is capped. In addition, as illustrated in  FIG. 13 , the idle ejection operation can be performed in a state where the nozzle formation surface of the liquid ejection head  52  and the cap  60  face each other. 
     In the present embodiment, although the first sequence can be applied as a sequence after the printing operation based on the operation instruction is completed, the retreating operation of the support body (Step S 15 ) is not performed in the present embodiment. The first sequence when applied to the liquid ejection apparatus  51  in the present embodiment will be briefly described based on  FIG. 11 . When a series of printing operations based on the operation instruction is completed (Step S 11 ), the non-printing vibration operation is started (Step S 12 ), and subsequently, an operation of detecting the ejection abnormality is performed (Step S 13 ). After the detection operation, the non-printing vibration operation is stopped (Step S 14 ), and thereafter the relative moving operation is performed to cause the cap  60  and the nozzle formation surface of the liquid ejection head  52  to face each other (Step S 16 ). That is, the carriage  55  is moved from the printing area on the platen  57  to the home position, and the nozzle formation surface of the liquid ejection head  52  is positioned on the cap  60  of the capping mechanism  59 . In this state, the idle ejection operation is performed (Step S 17 ). 
     As described above, in the present embodiment, the detection operation is started before the relative moving operation between the liquid ejection head  52  and the cap  60  is started, and since the non-printing vibration operation is stopped after the detection operation, the time during which the non-printing vibration operation is continued is reduced. As a result, it is possible to reduce the amount of ink discharged in the ink discharge operation. Regarding the timing at which the operation of detecting the ejection failure is performed, in the present embodiment, the detection operation may be started simultaneously when the relative moving operation between the liquid ejection head  52  and the cap  60  is started. That is, in this case, the detection operation and the relative moving operation are performed in parallel. Also in this case, compared with the case where the detection operation is performed after the relative moving operation, it is possible to reduce the time during which the non-printing vibration operation is continued. In addition, by performing the detection operation and the relative moving operation in parallel, it is possible to reduce the processing time of the entire sequence after the printing operation is completed. 
     In addition, in the present embodiment, as the sequence after the printing operation is completed, the first sequence may not necessarily be performed, and similarly to the first embodiment, the first sequence and the second sequence may be switched according to the conditions such as the environmental temperature and the residual amount of ink in the ink cartridge  54 . In this case, in the present embodiment, the retreating operation of the support body in Step S 3  (Step S 3 ) in the second sequence illustrated in  FIG. 10  is not performed. 
     In each of the above embodiments, although the case where a series of printing operations based on the operation instruction is all completed is exemplified as the case where the liquid ejection operation is completed, the present disclosure is not limited thereto. For example, the first sequence can also be applied, or the first sequence and the second sequence can be switched as a sequence performed at the timing when the image to be printed is switched, or the timing when the recording sheet is switched (when duplex printing is performed, the timing when the printing surface is switched is included) when the medium to be printed is a sheet of recording sheet or the like, in the middle of a series of printing operations based on the operation instruction. That is, the first sequence or the second sequence may be performed during a series of printing operations based on the operation instruction. In this case, the end of the printing operation, which is a liquid ejection operation, means that the printing operation for each image or each medium is completed regardless of whether or not a series of printing operations based on the operation instruction is completed. Alternatively, in the serial printer as in the second embodiment, the first sequence can be applied, or the first sequence and the second sequence can be switched as a sequence performed between passes which are scanning units of the liquid ejection head  52 . In this case, the end of the printing operation, which is the liquid ejection operation, means that the printing operation of a predetermined pass is completed. Even in the case where the present disclosure is applied in such a case, the duration time of the non-printing vibration operation can be reduced, so that the progress of the thickening can be suppressed, and as a result, the discharge amount of the liquid in the discharge operation can be reduced. 
     Hereinbefore, although an ink jet liquid ejection head is described as an example of the liquid ejection head, the present disclosure can also be applied to another liquid ejection head in which the vibration operation is performed after the end of the liquid ejection operation on the basis of the operation instruction, and a liquid ejection apparatus including the same. For example, the present disclosure can be applied to a color material ejection head used to manufacture a color filter such as a liquid crystal display, an electrode material ejection head used to form an electrode such as an organic electro luminescence (EL) display, an field emission display (FED), a liquid ejection head including a plurality of bioorganic matter ejection heads and the like used to manufacture a biochip (biochemical element), and a liquid ejection apparatus including the same. 
     In the following, technical ideas and their effects and advantages which are grasped from the above-described embodiment and the modification will be described. 
     According to an aspect of the present disclosure, there is provided a control method of a liquid ejection apparatus including a liquid ejection head which has a nozzle formation surface on which a nozzle ejecting a liquid is formed, and a pressure generating element generating a pressure for ejecting the liquid from the nozzle, and performs a liquid ejection operation of ejecting the liquid onto a medium from the nozzle by driving the pressure generating element, an applying circuit which applies a drive waveform driving the pressure generating element to the pressure generating element, a cap configured to seal the nozzle formation surface, and an ejection failure detection portion which performs a detection operation of detecting ejection failure of the nozzle based on a residual vibration of the pressure generating element after applying the drive waveform to the pressure generating element by the applying circuit, the control method including starting a vibration operation of continuously applying the drive waveform for vibrating the liquid in the nozzle to the pressure generating element, after the liquid ejection operation is completed, starting the detection operation before a relative moving operation of relatively moving the liquid ejection head and the cap so as to face each other is completed, and stopping the vibration operation after the detection operation (first control method). 
     According to the liquid ejection apparatus of the present disclosure, the time during which the vibration operation performed in the state where the liquid ejection operation is not performed is continued is reduced. Therefore, the heat generation and the progress of the thickening of the liquid may be suppressed by driving the pressure generating element. As a result, the total amount of liquid discharged in the discharge operation of discharging the thickened liquid may be reduced by that amount. 
     In the first control method, the detection operation may be started simultaneously when the relative moving operation is started or before the relative moving operation is started (second control method). 
     According to this control method, compared with the case where the detection operation is performed after the relative moving operation, the duration time of the vibration operation may be further reduced. 
     In the first or second control method, the detection operation and the relative moving operation may be performed in parallel (third control method). 
     According to this control method, the processing time of the control after the liquid ejection operation is completed may be reduced by performing the detection operation and the relative moving operation in parallel. 
     In addition, in any one of the first to third control methods, the apparatus may further include a support body moving mechanism which performs a retreating operation of retreating a support body supporting a landing target of the liquid ejected from the nozzle from a position where the support body faces the nozzle formation surface, the retreating operation may be started before the relative moving operation, and the detection operation may be started before the retreating operation is completed (fourth control method). 
     According to this control method, compared with the case where the detection operation is performed after the retreating operation, the duration time of the vibration operation may be reduced. 
     Furthermore, in the fourth control method, the retreating operation may be started before the relative moving operation and the detection operation may be started simultaneously when the retreating operation is started or before the retreating operation is started (fifth control method). 
     According to this control method, since the detection operation is started simultaneously when the retreating operation is started or before the retreating operation is started, the duration time of the vibration operation may be further reduced. As a result, the total amount of liquid discharged in the discharge operation may be further reduced. 
     In addition, in the fifth control method, the detection operation and the retreating operation may be performed in parallel (sixth control method). 
     According to this control method, the processing time of control after the liquid ejection operation is completed may be reduced by performing the detection operation and the retreating operation in parallel. 
     In addition, in any one of the first to sixth control methods, an idle ejection operation of discharging the liquid in the nozzle may be executable by ejecting the liquid from the nozzle, and the idle ejection operation may be performed after the vibration operation (seventh control method). 
     According to this control method, the liquid thickened by the vibration operation may be discharged. 
     Furthermore, in the seventh control method, the drive waveform in the vibration operation may be changed according to any of or a combination of a temperature and a humidity of an environment in which the liquid ejection apparatus is installed, and an elapsed time from a last performed idle ejection operation (eighth control method). 
     According to this control method, it is possible to perform a more appropriate vibration operation according to any of the temperature, the humidity of the environment, the elapsed time from the last performed idle ejection operation, or the combination thereof. 
     In addition, in the eighth control method, when an environmental temperature is a second value higher than a first value, an environmental humidity is a fourth value lower than a third value, or an elapsed time from the last performed idle ejection operation is a sixth value longer than a fifth value, a wave height or a frequency of the drive waveform in the vibration operation may be set higher than a wave height or a frequency of the drive waveform in the vibration operation when the environmental temperature is the first value, the environmental humidity is the third value, or the elapsed time from the last performed idle ejection operation is the fifth value (ninth control method). 
     According to this control method, it is possible to perform the more appropriate non-printing vibration operation according to the situation where the liquid is further thickened. 
     Furthermore, in the eighth or ninth control method, an amount of the liquid discharged in the idle ejection operation may be changed according to the drive waveform in the vibration operation (tenth control method). 
     According to this control method, it is possible to further reduce the excess and deficiency of the discharge amount of liquid in the idle ejection operation. 
     In addition, in any one of the seventh to tenth control methods, the liquid ejection head may include a liquid storage member which stores the liquid, a first sequence to which any one of the first to tenth control methods is applied and a second sequence in which the detection operation is performed after the relative moving operation and the idle ejection operation may be switchable, and the first sequence and the second sequence may be switched according to an amount of the liquid stored in the liquid storage member (eleventh control method). 
     According to this control method, when the amount of liquid stored in the liquid storage member is relatively large, by switching to the second sequence, detection accuracy cab be enhanced compared to the first sequence. When the amount of liquid stored in the liquid storage member is relatively small, by switching to the first sequence, the progress of thickening of the liquid may be suppressed and the time during which the liquid ejection operation is possible as much as possible may be extended. 
     In any one of the first to eleventh control methods, a cleaning operation of discharging the liquid from the nozzle may be executable by pressurizing an upstream of the nozzle or depressurizing an outside of the nozzle and the detection operation may be performed again after the idle ejection operation or the cleaning operation is performed, when the ejection failure of the nozzle is detected in the detection operation (twelfth control method). 
     According to this control method, the detection accuracy of the ejection failure in the detection operation may be further enhanced.