JP5621299B2 - Fluid ejecting apparatus and fluid ejecting head maintenance method - Google Patents

Description

  The present invention relates to a fluid ejecting apparatus and a fluid ejecting head maintenance method.

  As a fluid ejecting apparatus that ejects a fluid, for example, an ink jet recording apparatus described in Patent Document 1 is known. An ink jet recording apparatus is an apparatus that records characters, images, and the like on a recording medium (medium), and is configured to selectively eject ink onto a recording medium from nozzles provided in a recording head. In this fluid ejecting apparatus, the maintenance operation of the recording head is periodically performed in order to maintain or restore good ejecting characteristics.

  Examples of such a maintenance operation include a flushing operation and a suction operation. The flushing operation prevents ink from clogging due to ink thickening and solidification caused by evaporation of ink from the nozzles of the recording head, dust adhesion, and air bubbles, and to prevent printing defects. This is an operation for forcibly discharging the ink in the nozzle separately from all the ejections. In the suction operation, after the recording head is capped with a cap member, the suction pump is driven to adjust the meniscus by forcibly sucking ink with high viscosity or adhering dust from each nozzle, so that ink is normally discharged from the recording head. It is an operation to inject.

Japanese Patent Laid-Open No. Sho 63-256442

  However, in the flushing operation, ink that has increased in viscosity to some extent cannot be discharged, and in such a case, it is necessary to perform a suction operation. On the other hand, the suction operation takes a longer time to return than the flushing operation, and the amount of ink consumed increases for the purpose of merely discharging the thickened ink.

  In view of the circumstances as described above, it is an object of the present invention to provide a fluid ejecting apparatus and a fluid ejecting head maintenance method capable of maintaining fluid ejecting characteristics while suppressing fluid discharge.

A fluid ejecting apparatus according to the present invention includes a plurality of nozzles that discharge fluid, and a plurality of pressure chambers that communicate with each of the plurality of nozzles and that are arranged adjacent to each other via a wall portion and store the fluid. A fluid ejecting head, a pressurizing operation for increasing the pressure of a first pressure chamber communicated with the predetermined nozzle when discharging the fluid from the predetermined nozzle among the plurality of nozzles, and the first pressure A pressure reducing operation for reducing the pressure of the second pressure chamber adjacent to the chamber, and a controller that performs the pressure reduction operation in synchronization with the pressure of the third pressure chamber adjacent to the second pressure chamber being not changed. Features.

  According to such a configuration, the wall portion of the first pressure chamber tends to be deformed toward the outside of the first pressure chamber by the pressurizing operation, and the wall portion is deformed toward the inside of the second pressure chamber by the decompression operation. try to. When the pressurizing operation and the depressurizing operation are performed in synchronization, the wall portion is deformed with a stronger force toward the outside of the first pressure chamber than when only the pressurizing operation is performed. For this reason, the pressurization of a 1st pressure chamber can be strengthened and the discharge characteristic of a fluid can be improved. Accordingly, for example, the thickened fluid in the fluid ejecting head can be ejected by the ejecting operation without performing the suction operation, and thus the fluid ejection characteristics can be maintained while suppressing the fluid ejection amount. .

The fluid ejecting apparatus, the control unit, the pressure of a plurality of said pressure chambers have a separately variability pressure change part, the pressure fluctuation portion is deformed by an electric signal is provided for each of the pressure chamber the A piezoelectric element that varies the pressure in the pressure chamber by deformation; and the fluid ejecting head includes a diaphragm that is provided across the plurality of pressure chambers and that can individually vary the volumes of the plurality of pressure chambers. The piezoelectric element is provided on the diaphragm .
According to such a configuration, since the control unit can individually vary the pressures of the plurality of pressure chambers, the discharge characteristics can be enhanced for each nozzle.

In the fluid ejecting apparatus, the control unit deforms the piezoelectric element so that the pressure in the pressure chamber increases, and the first electric signal deforms the piezoelectric element so that the pressure in the pressure chamber decreases. switch 2 electrical signals and a have a electric signal supply unit to supply to each of the piezoelectric elements, the first electrical signal is a voltage signal having a predetermined waveform, said second electrical signal, said first It is an electrical signal having a waveform in which positive and negative are inverted with respect to the predetermined waveform of one electrical signal with reference to a predetermined value and the amplitude is reduced .
According to such a configuration, since the electrical signal supply unit can switch and supply the first electrical signal and the second electrical signal to each piezoelectric element, it is a case where the nozzle for discharging the fluid is appropriately switched. However , the discharge characteristic of the nozzle can be improved , the first electric signal is a voltage signal having a predetermined waveform, and the second electric signal is positive or negative with respect to a predetermined value with respect to the predetermined waveform of the first electric signal. since an electric signal having a waveform obtained by reducing the amplitude with reversing the, Ru can be synchronized with the depressurization operation and pressurizing operation more reliably.

The fluid ejection device, adjacent Ri fit the pressure chamber of the plurality of the pressure chamber, characterized in that it is connected to the next Ri fit the nozzle of the plurality of the nozzles.
According to this structure, adjacent Ri fit pressure chambers among the plurality of pressure chambers, because they are connected to adjacent Ri fit nozzles among the plurality of nozzles, it is easy to determine the positional relationship between the nozzle and the pressure chamber This makes it easy to control by the control unit.

In the fluid ejecting apparatus, the plurality of nozzles are arranged in one direction, and the control unit discharges the fluid in order along an arrangement direction of the plurality of nozzles.
According to such a configuration, the plurality of nozzles are arranged in one direction, and the control unit causes the fluid to be discharged in order along the arrangement direction of the plurality of nozzles. Can be performed.

Maintenance method of the fluid ejecting head according to the present invention, a plurality of nozzles for ejecting a fluid, and is arranged to fit Ri next through the wall with which communicates with each of the plurality of the nozzle housing the fluid A maintenance method for a fluid ejecting head having a plurality of pressure chambers, wherein when the fluid is discharged from a predetermined nozzle among the plurality of nozzles, the pressure in a first pressure chamber communicated with the predetermined nozzle is increased. a pressurizing operation, and performs to synchronize the depressurization operation and reducing the pressure in the second pressure chamber to fit Ri next to the first pressure chamber.

  According to such a configuration, the wall portion of the first pressure chamber tends to be deformed toward the outside of the first pressure chamber by the pressurizing operation, and the wall portion is deformed toward the inside of the second pressure chamber by the decompression operation. try to. When the pressurizing operation and the depressurizing operation are performed in synchronization, the wall portion is deformed with a stronger force toward the outside of the first pressure chamber than when only the pressurizing operation is performed. For this reason, the pressurization of a 1st pressure chamber can be strengthened and the discharge characteristic of a fluid can be improved. Accordingly, for example, the thickened fluid in the fluid ejecting head can be ejected by the ejecting operation without performing the suction operation, and thus the fluid ejection characteristics can be maintained while suppressing the fluid ejection amount. .

1 is a partially exploded view showing a schematic configuration of a printer according to an embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a configuration of a recording head. FIG. 3 is a cross-sectional view illustrating a partial configuration of a recording head. FIG. 2 is a plan view illustrating a configuration of a part of a recording head. FIG. 3 is a cross-sectional view illustrating a partial configuration of a recording head. FIG. 3 is a block diagram illustrating an electrical configuration of the printer. A graph for explaining an example of a maintenance operation. FIG. 4 is a cross-sectional view illustrating a state of a recording head in an example of a maintenance operation. FIG. 3 is a schematic diagram of a recording head for explaining an example of a maintenance operation. A graph for explaining an example of a maintenance operation. The graph for demonstrating the other example of maintenance operation | movement.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram illustrating a schematic configuration of a printing apparatus PRT (liquid ejecting apparatus) according to the present embodiment. In the present embodiment, for example, an ink jet type printing apparatus will be described as an example of the printing apparatus PRT.

  The printing apparatus PRT shown in FIG. 1 is an apparatus that performs a printing process while conveying a sheet-like medium M such as paper or a plastic sheet. The printing apparatus PRT includes a housing PB, an ink ejection mechanism IJ that ejects ink onto the medium M, an ink supply mechanism SP that supplies ink to the ink ejection mechanism IJ, a transport mechanism CV that transports the medium M, and an ink ejection. A maintenance mechanism MN that performs a maintenance operation of the mechanism IJ and a control device CONT that controls these mechanisms are provided.

  Hereinafter, an XYZ rectangular coordinate system is set, and the positional relationship of each component will be described with reference to the XYZ rectangular coordinate system as appropriate. In the present embodiment, for example, the conveyance direction of the medium M is the X direction, the direction perpendicular to the X direction on the conveyance surface of the medium M is the Y direction, and the direction perpendicular to the plane including the X axis and the Y axis is the Z direction. write. The rotation direction around the X axis is the θX direction, the rotation direction around the Y axis is the θY direction, and the rotation direction around the Z axis is the θZ direction.

  The housing PB is formed, for example, with the Y direction as a longitudinal direction. The ink jetting mechanism IJ, the ink supply mechanism SP, the transport mechanism CV, the maintenance mechanism MN, and the control unit CONT are attached to the housing PB. For example, a platen 13 is provided in the housing PB. The platen 13 is a support member that supports the medium M. The platen 13 is disposed, for example, at the center in the X direction of the housing PB. The platen 13 has a flat surface 13a oriented in the + Z direction. The flat surface 13a is used as a support surface that supports the medium M.

  The transport mechanism CV includes, for example, a transport roller and a motor that drives the transport roller. For example, the transport mechanism CV transports the medium M into the housing PB from the −X side of the housing PB and discharges the medium M from the + X side of the housing PB to the outside of the housing PB. The transport mechanism CV transports the medium M so that the medium M passes over the platen 13 inside the housing PB. In the transport mechanism CV, for example, the transport timing and transport amount are controlled by the control device CONT.

  The ink ejection mechanism IJ includes an ejection head HD that ejects ink, and a head moving mechanism AC that holds and moves the ejection head HD. The ejection head HD ejects ink toward the medium M sent onto the platen 13. The ejection head HD has an ejection surface HDa that ejects ink. The ejection surface HDa is directed in the −Z direction, for example, and is disposed so as to face the support surface 13a of the platen 13, for example.

  The head moving mechanism AC has a carriage 4. The ejection head HD is fixed to the carriage 4. The carriage 4 is in contact with a guide shaft 8 that extends in the longitudinal direction (X direction) of the housing PB. The ejection head HD and the carriage 4 are arranged, for example, in the + Z direction of the platen 13.

  In addition to the carriage 4, the head moving mechanism AC includes, for example, a pulse motor 9, a drive pulley 10 that is rotationally driven by the pulse motor 9, and a drive pulley 10 that is provided on the opposite side in the width direction of the housing PB. It has a rolling pulley 11 and a timing belt 12 that is stretched between the driving pulley 10 and the idle pulley 11 and connected to the carriage 4. The carriage 4 is connected to the timing belt 12. The carriage 4 is provided to be movable in the Y direction as the timing belt 12 rotates. When moving in the Y direction, the carriage 4 is guided by a guide shaft 8.

  The ink supply mechanism SP supplies ink to the ejection head HD. For example, a plurality of ink cartridges 6 are accommodated in the ink supply mechanism SP. The printing apparatus PRT of this embodiment has a configuration (off-carriage type) in which the ink cartridge 6 is accommodated at a position different from the ejection head HD. The ink supply mechanism SP includes, for example, a supply tube TB that connects the ejection head HD and the ink cartridge 6. The ink supply mechanism SP has a pump mechanism (not shown) that supplies ink stored in the ink cartridge 6 to the ejection head HD via the supply tube TB.

  The maintenance mechanism MN is disposed at the home position of the ejection head HD. This home position is set, for example, in an area outside the area where printing is performed on the medium M. In the present embodiment, for example, the home position is set on the + Y side of the platen 13. The home position is a place where the ejection head HD stands by, for example, when the printing apparatus PRT is powered off or when recording is not performed for a long time.

  The maintenance mechanism MN includes, for example, a capping mechanism CP that covers the ejection surface HDa of the ejection head HD, a wiping mechanism WP that wipes the ejection surface HDa, and the like. A suction mechanism SC such as a suction pump is connected to the capping mechanism CP. By the suction mechanism SC, the capping mechanism CP can suck the space on the ejection surface HDa while covering the ejection surface HDa, for example. Waste ink discharged from the ejection head HD to the maintenance mechanism MN side is collected by, for example, a waste liquid collection mechanism (not shown).

FIG. 2 is a side sectional view showing the configuration of the ejection head HD. FIG. 3 is a cross-sectional view of a main part for explaining the configuration of the ejection head HD.
As shown in FIG. 2, the ejection head HD includes an introduction needle unit 17, a head case 18, a flow path unit 19, and an actuator unit 20.

  Two ink introduction needles 22 are attached to the upper surface of the introduction needle unit 17 side by side with the filter 21 interposed. An ink introduction path 23 corresponding to each ink introduction needle 22 is formed inside the introduction needle unit 17. The upper end of the ink introduction path 23 is connected to the ink introduction needle 22 through the filter 21. The lower end of the ink introduction path 23 is connected to a case flow path 25 inside the head case 18 via a packing 24. A sub tank 2 is attached to each of the ink introduction needles 22.

  The sub tank 2 is formed using a resin material such as polypropylene, for example. An ink chamber 27 is provided in the sub tank 2. The ink chamber 27 has a concave portion 27a formed in a mortar shape, for example. The recess 27a has an opening 27b. A transparent elastic sheet 26 is attached to the opening 27b. A communication hole 27c is formed at the bottom of the recess 27a. The communication hole 27c is formed to communicate between the recess 27a of the ink chamber 27 and the ink supply chamber 27d. The ink supply chamber 27d is connected to, for example, a supply tube TB. For example, a filter (not shown) or the like is provided in a connection portion of the ink supply chamber 27d with the supply tube TB, for example.

  The elastic sheet 26 is stuck so as to close the opening 27b. The elastic sheet 26 expands and contracts according to the pressure in the ink chamber 27. For example, when the pressure in the ink chamber 27 becomes higher than the external pressure, the elastic sheet 26 expands toward the outside of the recess 27a, and the volume of the ink chamber 27 increases. When the pressure in the ink chamber 27 becomes lower than the external pressure, the ink chamber 27 expands toward the inside of the recess 27a, and the volume of the ink chamber 27 decreases.

  A valve 27 e is attached to the elastic sheet 26. The valve 27e is connected to the ink supply chamber 27d from the recess 27a through the communication hole 27c, and is formed to open and close the communication hole 27c from the ink supply chamber 27d side. The valve 27e opens and closes the communication hole 27c in conjunction with the expansion and contraction of the elastic sheet 26. Specifically, the communication hole 27c is opened when the elastic sheet 26 expands in the direction of decreasing the volume of the ink chamber 27, and the communication hole when the elastic sheet 26 expands in the direction of increasing the volume of the ink chamber 27. 27c is closed. An urging member 27f for applying a predetermined elastic force is attached to the valve 27e, and the opening / closing pressure of the communication hole 27c is adjusted.

  The sub tank 2 is connected to the needle connecting portion 28. The needle connection portion 28 is a portion that connects the ink introduction needle 22 sub-tank 2 and the ink introduction needle 22. In the concave portion 27 a of the ink chamber 27, a connection channel 29 connected to the needle connection portion 28 is formed. A seal material 31 into which the ink introduction needle 22 is fitted with almost no gap is provided in the internal space of the needle connection portion 28. By fitting the ink introduction needle 22 into the sealing material 31, the sub tank 2 and the introduction needle unit 17 are connected with almost no leakage.

  As shown in FIG. 3, the head case 18 is formed using a synthetic resin or the like. The head case 18 is formed in a box shape so as to have a hollow portion, for example. The head case 18 has an introduction needle unit 17 attached to the upper end side via a packing 24. A flow path unit 19 is joined to the lower end surface of the head case 18. The actuator unit 20 is accommodated in a hollow portion 37 formed inside the head case 18.

  A case channel 25 is provided inside the head case 18 so as to penetrate the height direction. The upper end of the case flow path 25 communicates with the ink introduction path 23 of the introduction needle unit 17 through the packing 24. The lower end of the case flow path 25 communicates with the common ink chamber 44 in the flow path unit 19. Therefore, the ink L introduced from the ink introduction needle 22 is supplied to the common ink chamber 44 side through the ink introduction path 23 and the case flow path 25.

  The actuator unit 20 supplies, for example, a plurality of piezoelectric vibrators 38 arranged in a comb shape, a fixed plate 39 that holds the piezoelectric vibrator 38, and a drive signal from the control device CONT to the piezoelectric vibrator 38. And a flexible cable 40.

  The piezoelectric vibrator 38 is fixed so that the lower end portion in the figure protrudes from the lower end surface of the fixed plate 39. Thus, each piezoelectric vibrator 38 is mounted on the fixed plate 39 in a so-called cantilever state. The fixed plate 39 that supports each piezoelectric vibrator 38 is made of, for example, stainless steel having a thickness of about 1 mm. For example, a surface different from the surface on which the piezoelectric vibrator 38 is fixed is bonded to the inner wall surface of the case that defines the hollow portion 37.

  The flow path unit 19 includes a vibration plate 41, a flow path substrate 42 and a nozzle substrate 43. The diaphragm 41, the flow path substrate 42, and the nozzle substrate 43 are bonded in a stacked state. The flow path unit 19 constitutes a series of ink flow paths (liquid flow paths) from the common ink chamber 44 through the ink supply port 45 and the pressure chamber 46 to the nozzle NZ. The pressure chamber 46 is formed such that the direction perpendicular to the arrangement direction (nozzle row direction) of the nozzles NZ is the longitudinal direction.

  The common ink chamber 44 is connected to the case flow path 25. The common ink chamber 44 is a chamber into which the ink L from the ink introduction needle 22 side is introduced. The common ink chamber 44 is connected to the ink supply port 45. The ink L introduced into the common ink chamber 44 is distributed to each pressure chamber 46 through the ink supply port 45.

  The nozzle substrate 43 is disposed at the bottom of the flow path unit 19. A plurality of nozzles NZ are formed on the nozzle substrate 43 at a pitch (for example, 180 dpi) corresponding to the dot formation density of an image or the like formed on the medium M. As the nozzle substrate 43, for example, a metal plate material such as stainless steel is used.

  FIG. 4 is a diagram illustrating a partial configuration of the ejection surface HDa of the ejection head HD. As shown in FIG. 4, nozzles NZ are formed on the nozzle substrate 43 in two rows, for example, and four sets of nozzles NZ in the two rows are formed, for example. The number of sets corresponding to each sub tank 2 is formed in the nozzle NZ, for example. In the present embodiment, as shown in FIG. 1, four sub tanks 2 are provided, so that, for example, four sets of two rows of nozzles NZ are provided, and a total of eight rows of nozzles NZ are provided. For example, one row of the nozzles NZ includes 180 nozzles NZ arranged in the X direction. FIG. 4 shows some (2 rows × 16) nozzles NZ among 8 rows × 180 nozzles NZ.

  The flow path substrate 42 is disposed between the nozzle substrate 43 and the vibration plate 41. The flow path substrate 42 has a flow path portion that becomes an ink flow path, specifically, a hollow portion that becomes a common ink chamber 44, an ink supply port 45, and a pressure chamber 46. The flow path substrate 42 is formed using a crystalline base material such as a silicon wafer. In the present embodiment, for example, the silicon wafer is manufactured by performing an anisotropic etching process.

  The vibration plate 41 is a double-structured plate-like member obtained by laminating an elastic film on the surface of a metal plate such as stainless steel. An island portion 48 is formed in a portion of the vibration plate 41 corresponding to the pressure chamber 46. Around the island portion 48, a metal plate is removed by etching or the like to form a recess. An elastic film is exposed in the recess. The tip surface of the piezoelectric vibrator 38 is joined to the island portion 48. The island part 48 functions as a diaphragm part that deforms the elastic film. That is, the island portion 48 is configured to deform the surrounding elastic film in accordance with the operation of the piezoelectric vibrator 38. The diaphragm 41 seals one opening surface of the flow path substrate 42 and also functions as a compliance portion 49. About the part equivalent to this compliance part 49, it has the structure which the elastic film exposed, like the diaphragm part.

  In the above-described ejection head HD, when a drive signal is supplied to the piezoelectric vibrator 38 through the flexible cable 40, the piezoelectric vibrator 38 expands and contracts in the longitudinal direction (vertical direction in the figure), and the piezoelectric vibrator 38 moves to the island portion 48. To move the elastic film. When the elastic film is deformed in a direction close to or away from the pressure chamber 46, the volume of the pressure chamber 46 changes, and a pressure fluctuation occurs in the ink L in the pressure chamber 46. The ink droplet D is ejected from the nozzle NZ by this pressure fluctuation.

FIG. 5 is a diagram illustrating a configuration of the flow path unit 19 of the ejection head HD.
FIG. 5 shows an example of a plurality (for example, three) of nozzles NZ1, NZ2, and NZ3 arranged in the X direction. Pressure chambers 46a to 46c are connected to the nozzles NZ1 to NZ3, respectively. Piezoelectric vibrators 38a to 38c, which are pressure fluctuation portions, are attached to the pressure chambers 46a to 46c, respectively. The piezoelectric vibrators 38a to 38c are provided so as to be individually deformable under the control of the control device CONT, for example.

  The nozzles NZ1 to NZ3 are arranged adjacent to each other in the X direction, for example. Corresponding to the arrangement of the nozzles NZ1 to NZ3, the pressure chambers 46a to 46c are similarly arranged adjacent to each other in the X direction. Thus, the nozzle NZ and the pressure chamber 46 are arranged so as to correspond to each other. The pressure chamber 46a is divided by, for example, a wall 47a and a wall 47b. The pressure chamber 46b is partitioned by, for example, a wall 47b and a wall 47c. The pressure chamber 46c is divided by, for example, a wall 47c and a wall 47d.

  Thus, in the example shown in FIG. 5, the wall part 47b and the wall part 47c are each arrange | positioned between two pressure chambers. Therefore, the pressure chamber 46a is disposed adjacent to the pressure chamber 46b through the wall portion 47b. Further, the pressure chamber 46c is disposed adjacent to the pressure chamber 46b through the wall portion 47c.

FIG. 6 is a block diagram showing an electrical configuration of the printing apparatus PRT.
The printing device PRT includes a control device CONT that controls the operation of the entire printing device PRT. Connected to the control device CONT are an input device 59 for inputting various information relating to the operation of the printing device PRT, a storage device 60 storing various information relating to the operation of the printing device PRT, a measuring device 61 capable of measuring time, and the like. The above-described transport mechanism CV, head moving mechanism AC, maintenance mechanism MN, and the like are connected.

  The printing apparatus PRT includes a drive signal generator 62 that generates a drive signal to be input to each piezoelectric vibrator 38. The drive signal generator 62 is connected to the control device CONT. The drive signal generator 62 receives data indicating the amount of change in the voltage value of the ejection pulse input to the piezoelectric vibrator 38 of the ejection head HD and a timing signal that defines the timing for changing the voltage of the ejection pulse. The drive signal generator 62 is provided so that a drive signal can be individually supplied to each piezoelectric vibrator 38.

  For example, the control device CONT controls the drive signal generator 62 to generate two types of drive signals. As such two types of drive signals, as shown in FIG. 7, specifically, a first electric signal that deforms the piezoelectric vibrator 38 so that the pressure in the pressure chamber 46 increases, and the pressure in the pressure chamber 46. And a second electric signal that deforms the piezoelectric vibrator 38 so as to decrease.

  As shown in FIG. 7, the first electric signal is a voltage signal having a predetermined waveform whose voltage value changes according to time, for example. The output value of the first electric signal changes, for example, at the reference voltage value at time t0 to t1. The piezoelectric vibrator 38 has a property that it contracts most at the maximum voltage value in the first electric signal and has the smallest deformation amount at the minimum voltage value.

  In the first electric signal, the output value increases from time t1 to time t2, and reaches the maximum voltage value at time t2. As the output value increases, the piezoelectric vibrator 38 starts to shrink, and when the first electric signal has the maximum voltage value, the deformation amount (shrinkage amount) of the piezoelectric vibrator 38 is maximized. At this time, the volume of the pressure chamber 46 is deformed in the expanding direction, and ink is supplied from the ink supply port 45 to the pressure chamber 46. And between the time t2-t3, the said maximum voltage value is maintained and the expansion state of the pressure chamber 46 is also maintained.

  When the first electric signal reaches time t3, the output value starts to decrease, the output value decreases from time t3 to t4, and becomes the minimum voltage value at time t4. As the output value decreases, the piezoelectric vibrator 38 rapidly expands from the contracted state. Accordingly, the pressure chamber 46 is rapidly contracted from the expanded state, the ink in the pressure chamber 46 is pressurized, and the ink is ejected from the nozzle NZ. In FIG. 7, the difference between the maximum voltage value and the minimum voltage value is expressed as Vh, for example.

  In the first electric signal, the minimum voltage value is maintained between times t4 and t5. When the time t5 is reached, the voltage value starts increasing, the output value increases from time t5 to t6, and becomes the reference voltage value at time t6. For this reason, the piezoelectric vibrator 38 once contracted from the initial state returns to the length of the initial state again.

  On the other hand, the second electric signal is an electric signal having a waveform in which positive and negative are inverted with respect to the waveform of the first electric signal shown in FIG. 7 and the amplitude is reduced. Specifically, when the time t1 is reached, the output value starts to decrease, the output value decreases from time t1 to time t2, and reaches the minimum voltage value at time t2. When the output value decreases, the piezoelectric vibrator 38 starts to expand, and when the second electric signal has the minimum voltage value, the deformation amount (elongation amount) of the piezoelectric vibrator 38 becomes maximum. Due to the deformation of the piezoelectric vibrator 38, the island portion 48 is pulled, and the pressure chamber 46 is decompressed. The minimum voltage value is maintained between times t2 and t3.

  When the second electric signal reaches time t3, the output value starts to increase, the output value increases from time t3 to t4, and reaches the maximum voltage value at time t4. The maximum voltage value at this time is a value higher than the reference voltage value, for example. As the output value increases, the amount of contraction of the piezoelectric vibrator 38 decreases. When the output value becomes higher than the reference voltage value, the piezoelectric vibrator 38 starts to shrink. When the second electric signal reaches the maximum voltage value, the deformation amount (contraction amount) of the piezoelectric vibrator 38 is maximized. Therefore, at this time, the piezoelectric vibrator 38 is once contracted from the initial state. In FIG. 7, the difference between the maximum voltage value and the minimum voltage value is expressed as Vk, for example. The difference Vk between the maximum voltage value and the minimum voltage value of the second electric signal is smaller than the difference Vh between the maximum voltage value and the minimum voltage value of the first electric signal.

  In the second electric signal, the maximum voltage value is maintained between times t4 and t5. When the time t5 is reached, the voltage value starts decreasing, the output value decreases from time t5 to t6, and becomes the reference voltage value at time t6. For this reason, the piezoelectric vibrator 38 once contracted from the initial state returns to the length of the initial state again. The width of the deformation amount of the piezoelectric vibrator 38 that is deformed by the second electric signal is smaller than the width of the deformation amount of the piezoelectric vibrator 38 that is deformed by the first electric signal.

Next, the operation of the printing apparatus PRT configured as described above will be described.
When performing the printing operation by the ejection head HD, the control device CONT arranges the medium M on the −Z side of the ejection head HD by the transport mechanism CV. After arranging the medium M, the control device CONT inputs a drive signal from the drive signal generator 62 related to the nozzle NZ to the piezoelectric vibrator 38 based on the image data of the image to be printed while moving the ejection head HD. .

  When a drive signal is input to the piezoelectric vibrator 38, the piezoelectric vibrator 38 expands and contracts. Due to the expansion and contraction of the piezoelectric vibrator 38, the volume of the pressure chamber 46 changes, and the pressure of the pressure chamber 46 containing ink fluctuates. Ink is ejected from the nozzle NZ due to the fluctuation of the pressure. A desired image is formed on the medium M by the ink ejected from the nozzles NZ. When the piezoelectric vibrator 38 is expanded and contracted, the first electric signal may be supplied to the piezoelectric vibrator 38. Further, a drive signal different from the first electric signal may be supplied to the piezoelectric vibrator 38.

  Inside the ejection head HD, bubbles may grow or the viscosity of the ink may increase with time, causing the ink ejection speed and amount to exceed desired values, resulting in ejection failure. . Therefore, the maintenance operation of the ejection head HD is performed arbitrarily or periodically, for example.

Examples of the maintenance operation include a flushing operation, a capping operation, and a cleaning operation.
For example, when performing the flushing operation, the control device CONT moves the ejection head HD to the home position, and sets the ejection surface HDa of the ejection head HD and the capping mechanism CP to face each other. In this state, the control device CONT vibrates the piezoelectric vibrator 38 via the drive signal generator 62. By this operation, ink is ejected from the nozzle NZ and discharged. The discharged ink is accommodated in the capping mechanism CP and collected via a waste liquid collecting mechanism (not shown).

  When performing this flushing operation, as shown in FIG. 8, the control device CONT, when discharging ink from a predetermined nozzle (for example, the nozzle NZ2) among the plurality of nozzles NZ, a pressure chamber communicated with the predetermined nozzle NZ. The pressurizing operation for increasing the pressure of 46b and the depressurizing operation for decreasing the pressure of the pressure chambers 46a and 46c adjacent to the pressure chamber 46b are performed in synchronization.

  Specifically, the control device CONT supplies the first electric signal from the drive signal generator 62 to the piezoelectric vibrator 38b that adjusts the pressure in the pressure chamber 46b, and synchronizes with the supply of the first electric signal. As described above, the second electric signal is supplied from the drive signal generator 62 to the piezoelectric vibrators 38a and 38c that adjust the pressures in the pressure chambers 46a and 46c.

  As shown in FIG. 8, first, the wall portions 47b and 47c that delimit the pressure chamber 46b are deformed toward the outside of the pressure chamber 46b by the pressurizing operation. On the other hand, due to the pressure reducing operation of the pressure chambers 46a and 46c adjacent to the pressure chamber 46b, a force to deform toward the inside of the pressure chambers 46a and 46c acts on the wall portions 47b and 47c.

  Therefore, by performing the pressurizing operation and the depressurizing operation in synchronization, the force for deforming the wall portions 47b and 47c toward the outside of the pressure chamber 46b is applied from both sides sandwiching the wall portion 47b and the wall portion 47c. Will join. For this reason, compared with the case where only the pressurizing operation of the pressure chamber 46b is performed, the pressure chamber 46b is strongly pressurized, and the ink discharge volume in one operation is increased correspondingly.

  For example, when only the pressurizing operation is performed on the pressure chamber 46b, the walls 47b and 47c are deformed. At this time, of the ceiling portions (the + Z side surface) of the pressure chambers 46a and 46c, for example, the portion where the elastic sheet is not exposed (the portion where the stainless steel of the vibration plate 41 remains) is the deformation of the walls 47b and 47c. May cause deformation to the + Z side.

  For this reason, for example, when pressure operations are simultaneously performed on the pressure chambers 46a to 46c, the amounts of displacement of the island portions 48a to 48c are reduced because of the mutual influence of the reaction force, and ink from the nozzles NZ1 to NZ3 is reduced. The emission characteristics will be lowered. On the other hand, in the present embodiment, the pressure chambers 46a and 46c adjacent to the pressure chamber 46b that performs the pressurizing operation are decompressed, so that the reaction force acting on the diaphragm 41 is absorbed. be able to. This avoids such a decrease in ink discharge characteristics.

  In the present embodiment, the control device CONT causes the plurality of nozzles NZ to sequentially discharge ink along the arrangement direction (X direction) of the nozzles NZ. For this ink discharging operation, the control device CONT discharges ink in, for example, four stages. Specifically, the operations A to D shown in FIGS. 9 and 10 are performed. FIG. 9 is a diagram illustrating a state of the flushing operation in a part of one nozzle row. FIG. 10 is a diagram illustrating signals supplied to the piezoelectric vibrator 38 during the flushing operation. In FIG. 9 and FIG. 10, 16 nozzles NZ in the nozzle row are representatively shown to correspond to FIG. 4.

  In the operation A, for example, the nozzle on the most + X side (nozzle indicated by # 1 in FIGS. 4, 9 and 10) NZ among the nozzle rows formed in the X direction, and three nozzles in the −X direction from the nozzle NZ. Ink is discharged from the nozzles NZ arranged at intervals (nozzles indicated as # 5, # 9, and # 13 in the figure).

  In this case, the control device CONT causes the pressure chambers 46 connected to the nozzles NZ (# 1, # 5, # 9, # 13) to discharge ink to perform a pressurizing operation. Therefore, the first electric signal is supplied to the piezoelectric vibrator 38 of the pressure chamber 46. For the nozzles NZ (# 2, # 4, # 6, # 8, # 10, # 12, # 14) adjacent to the nozzles from which ink is discharged, the pressure reducing operation is performed in synchronization with the pressure operation. Make it.

  In operation B, as shown in FIG. 9, one nozzle NZ (# 2, # 6,...) Arranged at a position shifted to the -X side with respect to the nozzle NZ that has ejected ink in operation A in the nozzle row. Ink is discharged from # 10, # 14). In this case, the control device CONT causes the pressure chambers 46 connected to the nozzles NZ (# 2, # 6, # 10, # 14) to discharge ink to perform a pressurizing operation. Further, the nozzles NZ (# 1, # 3, # 5, # 7, # 9, # 11, # 13, # 15) adjacent to the nozzle for discharging ink are depressurized so as to be synchronized with the pressurizing operation. Let the action take place.

  Therefore, as shown in FIG. 10, the first electric signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 2, # 6, # 10, # 14). The second electric signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 1, # 3, # 5, # 7, # 9, # 11, # 13, # 15).

  In the operation C, as shown in FIG. 9, one nozzle NZ (# 3, # 7,...) Arranged at a position shifted to the -X side with respect to the nozzle NZ that has ejected ink in the operation B in the nozzle row. Ink is discharged from # 11, # 15). In this case, the control device CONT causes the pressure chambers 46 connected to the nozzles NZ (# 3, # 7, # 11, # 15) to discharge ink to perform a pressurizing operation. For the nozzles NZ (# 2, # 4, # 6, # 8, # 10, # 12, # 14) adjacent to the nozzles from which ink is discharged, the pressure reducing operation is performed in synchronization with the pressure operation. Make it.

  Therefore, as shown in FIG. 10, the first electric signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 3, # 7, # 11, # 15). The second electrical signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 2, # 4, # 6, # 8, # 10, # 12, # 14).

  In operation D, as shown in FIG. 9, one nozzle NZ (# 4, # 8,...) Arranged at a position shifted to the -X side with respect to the nozzle NZ that has ejected ink in operation C in the nozzle row. Ink is discharged from # 12, # 16). In this case, the control device CONT causes the pressure chambers 46 connected to the nozzles NZ (# 4, # 8, # 12, # 16) to discharge ink to perform a pressurizing operation. For the nozzles NZ (# 3, # 5, # 7, # 9, # 11, # 13, # 15) adjacent to the nozzles that discharge ink, the pressure reducing operation is performed in synchronization with the pressure operation. Make it.

  Therefore, as shown in FIG. 10, the first electric signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 4, # 8, # 12, # 16). The second electrical signal is supplied to the piezoelectric vibrator 38 in the pressure chamber 46 (# 3, # 5, # 7, # 9, # 11, # 13, # 15).

  After the operation D is completed, the operations A to D may be repeated again as illustrated in FIGS. 9 and 10, or the flushing operation may be terminated together with the completion of the operation D. In the above operations A to D, four of the nozzles NZ arranged in the X direction discharge alternately.

  The piezoelectric vibrators 38 of the pressure chambers 46 connected to the four nozzles NZ are switched and supplied with both the first electric signal and the second electric signal in the operations A to D. The four piezoelectric vibrators 38 have periods during which neither the first electric signal nor the second electric signal is supplied during the operations A to D. During this period, the meniscus of the ink formed on the nozzle NZ is stabilized.

  The above is an example of the flushing operation. In addition to the flushing operation, for example, when performing the capping operation, the control device CONT moves the ejection head HD to the home position, and after the movement, moves the capping mechanism CP to the + Z side to eject the ejection head HD. The injection surface HDa is sealed, for example.

  When performing the cleaning operation, the control device CONT operates the suction mechanism SC in a state where the ejection surface HDa is sealed by the capping mechanism CP, and sucks the space on the ejection surface HDa. By this operation, the space on the ejection surface HDa becomes negative pressure, and ink is forcibly discharged from each nozzle NZ by the negative pressure. The discharged ink is sucked by the suction mechanism SC and recovered by a waste liquid recovery mechanism (not shown).

  As described above, according to the present embodiment, the wall portions 47b and 47c of the pressure chamber 46b try to be deformed toward the outside of the pressure chamber 46b by the pressurizing operation, and the wall portions 47b and 47c are changed to the pressure chamber by the decompression operation. Attempts to deform toward the inside of 46a and 46c. When the pressurizing operation and the depressurizing operation are performed in synchronization, the walls 47b and 47c are deformed with a stronger force toward the outside of the pressure chamber 46b than when only the pressurizing operation is performed. For this reason, the pressurization of the pressure chamber 46b can be strengthened, and the ink discharge characteristics can be enhanced. Accordingly, for example, thickened ink in the ejection head HD can be ejected by the flushing operation without performing the cleaning operation, and thus the ink ejection characteristics can be maintained while suppressing the ink ejection amount. .

The technical scope of the present invention is not limited to the above-described embodiment, and appropriate modifications can be made without departing from the spirit of the present invention.
For example, in the above embodiment, the case where the second electric signal has a waveform in which positive and negative are reversed with respect to the waveform of the first electric signal and the amplitude is reduced is described as an example. It is not limited to this. For example, as shown in FIG. 11, after the output value of the second electric signal becomes the minimum voltage value from time t2 to t3, the shape returns to the reference voltage value at time t4 without exceeding the reference voltage value. It does not matter.

  In the above embodiment, as an example in which the pressurizing operation and the depressurizing operation are performed in synchronization, for example, the case where the first electric signal and the second electric signal are supplied to the piezoelectric vibrator 38 at the same timing. Although described as an example, it is not limited to this. For example, the supply timing may be shifted between the first electric signal and the second electric signal. In this case, it is sufficient that the pressurizing operation of the piezoelectric vibrator 38 by the first electric signal and the pressure reducing operation of the piezoelectric vibrator 38 by the second electric signal overlap in time.

PRT ... Printer M ... Media PB ... Case IJ ... Ink ejection mechanism CV ... Conveying mechanism MN ... Maintenance mechanism CONT ... Control device HD ... Ejecting head NZ ... Nozzle 38 (38a-38c) ... Piezoelectric vibrator 46 (46a-46c) ) ... Pressure chambers 47a to 47d ... Wall 62 ... Drive signal generator

Claims (6)

A plurality of nozzles for discharging a fluid, and a fluid ejecting head having a plurality of pressure chambers that are communicated with each of the plurality of nozzles and arranged adjacent to each other via a wall, and contain the fluid;
When discharging the fluid from a predetermined nozzle among the plurality of nozzles, a pressurizing operation for increasing the pressure of the first pressure chamber communicated with the predetermined nozzle, and a second pressure adjacent to the first pressure chamber A fluid ejecting apparatus comprising: a control unit that synchronizes a pressure reducing operation for reducing the pressure of the chamber in a state where the pressure of the third pressure chamber adjacent to the second pressure chamber is not changed . The control unit has a pressure variation unit capable of individually varying the pressures of the plurality of pressure chambers,
The pressure fluctuation section includes a piezoelectric element that is provided for each pressure chamber and deforms by an electrical signal and varies the pressure of the pressure chamber by the deformation,
The fluid ejecting head includes a diaphragm provided across a plurality of the pressure chambers and capable of individually changing the volumes of the plurality of pressure chambers,
The fluid ejecting apparatus according to claim 1, wherein the piezoelectric element is provided on the diaphragm. Wherein the control unit includes a first electric signal deforming the piezoelectric element so that the pressure in the pressure chamber increases, a second electrical signal deforming the piezoelectric element so that the pressure in the pressure chamber is decreased, the A state in which neither the first electric signal nor the second electric signal is supplied, and an electric signal supply unit that supplies each piezoelectric element by switching between
The first electric signal is a voltage signal having a predetermined waveform,
The fluid ejecting apparatus according to claim 2, wherein the second electric signal is an electric signal having a waveform obtained by inverting the positive / negative with respect to the predetermined waveform of the first electric signal with reference to a predetermined value and reducing the amplitude. . The fluid ejection device according to any one of claims 1 to 3, wherein the adjacent pressure chambers among the plurality of pressure chambers are respectively connected to the adjacent nozzles among the plurality of nozzles. The plurality of nozzles are arranged in one direction,
The fluid ejecting apparatus according to any one of claims 1 to 4, wherein the control unit discharges the fluid in order along an arrangement direction of the plurality of nozzles. A maintenance method for a fluid ejecting head having a plurality of nozzles for discharging a fluid, and a plurality of pressure chambers that communicate with each of the plurality of nozzles and are arranged adjacent to each other via a wall portion There,
When discharging the fluid from a predetermined nozzle among the plurality of nozzles, a pressurizing operation for increasing the pressure of the first pressure chamber communicated with the predetermined nozzle, and a second pressure adjacent to the first pressure chamber A method of maintaining a fluid ejecting head , wherein the pressure reducing operation for reducing the pressure in the chamber is performed in a synchronized manner without changing the pressure in the third pressure chamber adjacent to the second pressure chamber .

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