JP2003311950A - Inkjet recorder and ink jet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recorder and an inkjet recording method in which the ejection characteristics of ink being ejected from each nozzle opening can be stabilized. <P>SOLUTION: A wait driving signal generating a wait driving field including at least a nonejection preliminary driving field being generated in the same direction as a preliminary driving field in correspondence thereto and having a generation interval shorter than that of the preliminary driving field is delivered, along with a driving signal generating a driving field for ejecting an ink drop, to at least one sidewall 29d, 29e of at least one waiting chamber 28e capable of ejecting ink from a chamber other than a specified chamber 28b thus sustaining uniform state of each chamber immediately before ejecting an ink drop. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type recording apparatus and an ink jet type recording method applied to, for example, a printer or a fax machine.

[0002]

2. Description of the Related Art Conventionally, there has been known an ink jet recording apparatus for recording characters and images on a recording medium by using an ink jet head having a plurality of nozzles for ejecting ink. In such an ink jet recording apparatus, nozzles of an ink jet head are provided on a head holder so as to face the recording medium, and the head holder is mounted on a carriage so that scanning is performed in a direction orthogonal to the conveying direction of the recording medium. It has become.

FIG. 13 shows an exploded schematic view of an example of a head chip of such an ink jet head, and FIG. 14 shows a cross section of a main part.

As shown in FIGS. 13 and 14, a plurality of chambers 102 are arranged side by side on the piezoelectric ceramic plate 101, and each chamber 102 is separated by a side wall 103. One end in the longitudinal direction of each chamber 102 extends to one end surface of the piezoelectric ceramic plate 101, and the other end does not extend to the other end surface, and the depth gradually decreases. Both side walls 10 in each chamber 102
An electrode 105 for applying a driving electric field is formed on the opening-side surface of No. 3 in the longitudinal direction.

A cover plate 107 is bonded to the opening side of the chamber 102 of the piezoelectric ceramic plate 101 with an adhesive 109. The cover plate 107 has a common ink chamber 111 that serves as a recess communicating with the shallower other end of each chamber 102, and an ink supply port 112 that penetrates from the bottom of the common ink chamber 111 in the opposite direction to the chamber 102. Have and.

Further, a nozzle plate 115 is joined to the end surface of the joined body of the piezoelectric ceramic plate 101 and the cover plate 107 where the chamber 102 is open, and the nozzle plate 115 is located at a position facing each chamber 102. Has a nozzle opening 117 formed therein.

The cover plate 107 is provided on the opposite side of the piezoelectric ceramic plate 101 from the nozzle plate 115.
A wiring board 120 is fixed to the surface opposite to the surface. A wiring 122 is formed on the wiring board 120, which is connected to each electrode 105 by a bonding wire 121 or the like, and a drive voltage can be applied to the electrode 105 via the wiring 122.

In the head chip thus constructed,
When ink is filled in each chamber 102 from the ink supply port 112 and a predetermined driving electric field is applied to the side walls 103 on both sides of the predetermined chamber 102 via the electrodes 105, the side wall 103 is flexibly deformed and the inside of the chamber 102 is changed. The volume temporarily changes, whereby the ink in the chamber 102 is ejected from the nozzle openings 117.

For example, as shown in FIG.
When ink is ejected from the nozzle opening 117 corresponding to 02a, the electrode 105a in the chamber 102a,
A positive drive voltage is applied to 105b, and the electrodes 105c and 105d facing each other are grounded.
As a result, the chamber 10 is attached to the side walls 103a and 103b.
If a driving electric field in the direction toward 2a acts and is orthogonal to the polarization direction of the piezoelectric ceramic plate 101, the side walls 103a and 103b are flexibly deformed in the chamber 102a direction by the piezoelectric thickness sliding effect, and the volume in the chamber 102a decreases. Pressure on the ink increases and the nozzle opening 1
Ink is ejected from 17.

[0010]

However, in the ink jet head mounted in the above-mentioned conventional ink jet recording apparatus, the ejection rate such as the position of the chambers in the arrangement direction, the number of ejected ink droplets, or the ejection frequency of ink droplets is used. There is a problem that the ejection characteristics such as the ejection amount and ejection speed of each ink drop vary due to the difference in

For example, there is a problem in that the ejection speed of ink drops differs between a chamber arranged on the end side of the ink jet head and a chamber arranged at another position. In addition, ink droplets are ejected between a case where a plurality of ink droplets are continuously ejected from a nozzle opening which communicates with a predetermined chamber and a case where ink droplets are ejected sporadically from a nozzle opening which communicates with a chamber in a standby state. There is a problem that there is a difference in speed. Further, there is a problem in that there is a difference in the ejection amount of ink droplets when ejecting ink droplets from all the nozzle openings and when ejecting ink droplets sporadically from a predetermined nozzle opening.

Further, such a problem is likely to occur particularly in a low temperature environment, that is, when the viscosity of the ink is relatively high.

In view of such circumstances, it is an object of the present invention to provide an ink jet recording apparatus and an ink jet recording method capable of stabilizing the ejection characteristics of ink ejected from each nozzle opening.

[0014]

According to a first aspect of the present invention for solving the above-mentioned problems, a plurality of chambers communicating with nozzle openings and filled with ink are arranged side by side on a piezoelectric ceramic plate, and both chambers are provided on both sides of each chamber. An ink jet head having an electrode provided on a side wall is provided, and a pre-driving electric field for temporarily increasing the volume in the chamber on the side wall via the electrode and a volume in the chamber that is continuous with the pre-driving electric field. At least one standby chamber capable of ejecting ink in a chamber other than a predetermined chamber for ejecting ink, in an ink jet recording apparatus that ejects ink by generating a driving electric field including an ejection driving electric field Corresponding to the pre-driving electric field on at least one side wall of the It is characterized by further comprising drive means for outputting a standby drive signal for generating a standby drive electric field including at least a non-ejection preliminary drive electric field having a generation period shorter than the preliminary drive electric field together with the drive signal for generating the drive electric field. It is in an inkjet recording device.

A second aspect of the present invention is the ink jet recording apparatus according to the first aspect, wherein the peak of the non-ejection pre-driving electric field is substantially the same as the peak of the pre-driving electric field. .

According to a third aspect of the present invention, in the first or second aspect, when the generation period of the preliminary driving electric field is x and the interval between the preliminary driving electric field and the ejection driving electric field is y, In the ink jet recording apparatus, the generation period of the ejection driving electric field is a length represented by 2x-y.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the generation period of the non-ejection preliminary drive electric field is 1/2 or less of the generation period of the preliminary drive electric field. It is a characteristic inkjet recording device.

A fifth aspect of the present invention is the ink jet system according to the fourth aspect, wherein the generation period of the non-ejection pre-driving electric field is 1/10 or less of the generation period of the pre-driving electric field. It is in the recording device.

A sixth aspect of the present invention is the non-ejection according to any one of the first to fifth aspects, in which the standby drive electric field is generated in the same direction as the ejection drive electric field corresponding to the ejection drive electric field. An inkjet recording apparatus is characterized by including a driving electric field.

A seventh aspect of the present invention is the ink jet system according to any one of the first to sixth aspects, characterized in that the standby drive electric field is generated corresponding to a standby chamber immediately before ink is ejected. It is in the recording device.

An eighth aspect of the present invention is the ink jet recording apparatus according to any one of the first to sixth aspects, wherein the standby drive electric field is generated corresponding to all standby chambers. .

A ninth aspect of the present invention is the ink jet recording method according to any one of the first to eighth aspects, wherein the standby drive electric field is generated corresponding to both sidewalls of the standby chamber. On the device.

A tenth aspect of the present invention is the ink jet system according to any one of the first to ninth aspects, characterized in that the standby drive electric field is generated corresponding to only one side wall of the standby chamber. It is in the recording device.

In an eleventh aspect of the present invention, in any one of the first to tenth aspects, all of the electrodes are individual electrodes to which the drive signal or the standby drive signal is independently output. It is a characteristic inkjet recording device.

In a twelfth aspect of the present invention according to any one of the first to tenth aspects, a pair of electrodes facing each other in the chamber are provided with a pair of individual electrodes to which the drive signal or the standby drive signal is output. The inkjet recording apparatus is characterized in that it is an electrode.

A thirteenth aspect of the present invention is any one of the first to tenth aspects, wherein between each of the chambers,
In the ink jet recording apparatus, a dummy chamber not filled with the ink is provided, and the electrode is provided on a side wall in the dummy chamber.

A fourteenth aspect of the present invention comprises an ink jet head in which a plurality of chambers communicating with the nozzle openings and filled with ink are arranged side by side in a piezoelectric ceramic plate, and electrodes are provided on side walls on both sides of each chamber. And driving by a pre-driving electric field for temporarily increasing the volume in the chamber on the side wall through the electrode and an ejection driving electric field continuous with the pre-driving electric field and temporarily reducing the volume in the chamber. In an inkjet recording method of ejecting ink by generating an electric field, the pre-driving electric field is provided on at least one side wall of at least one standby chamber capable of ejecting ink in a chamber other than a predetermined chamber for ejecting ink. Corresponding to the pre-driving electric field and generated in the same direction as the pre-driving electric field The standby driving signals for generating the standby driving electric field including at least a short non-ejection preliminary driving electric field, in an ink jet recording method and outputs the driving signal to generate the driving electric field.

A fifteenth aspect of the present invention is the ink jet recording method according to the fourteenth aspect, wherein the peak of the non-ejection pre-driving electric field is substantially the same as the peak of the pre-driving electric field. .

The sixteenth aspect of the present invention is the fourteenth or fifteenth aspect.
In the above aspect, the generation period of the preliminary driving electric field is x, and the interval between the preliminary driving electric field and the ejection driving electric field is y.
Then, the generation period of the ejection driving electric field is 2xy
In the ink jet recording method, the length is represented by

In a seventeenth aspect of the present invention, in any one of the fourteenth to sixteenth aspects, the generation period of the non-ejection preliminary drive electric field is 1/2 or less of the generation period of the preliminary drive electric field. It is a characteristic inkjet recording method.

An eighteenth aspect of the present invention is the ink jet system according to the seventeenth aspect, characterized in that the generation period of the non-ejection pre-driving electric field is 1/10 or less of the generation period of the pre-driving electric field. It is in the recording method.

In a nineteenth aspect of the present invention based on any one of the fourteenth to eighteenth aspects, the non-ejection driving electric field is generated in the same direction as the ejection driving electric field corresponding to the ejection driving electric field. An inkjet recording method is characterized by including an ejection driving electric field.

An twentieth aspect of the present invention is the ink jet recording apparatus according to any one of the fourteenth to nineteenth aspects, characterized in that the non-ejection driving electric field is generated corresponding to a standby chamber immediately before ink ejection. It is in the formula recording method.

A twenty-first aspect of the present invention is the ink-jet recording method according to any one of the fourteenth to nineteenth aspects, characterized in that the non-ejection driving electric field is generated corresponding to all standby chambers. is there.

A twenty-second aspect of the present invention is the ink-jet type apparatus according to any one of the fourteenth to twenty-first aspects, characterized in that the non-ejection drive electric field is generated corresponding to both sidewalls of the standby chamber. It is in the recording method.

The twenty-third aspect of the present invention is the ink jet printer according to any one of the fourteenth to twenty-first aspects, characterized in that the non-ejection drive electric field is generated corresponding to only one side wall of the standby chamber. It is in the formula recording method.

In the present invention, since the standby driving electric field is generated on the side wall of the standby chamber in which the ink is not ejected, the state of the chamber immediately before the ink is ejected can be always maintained in a constant state. The ejection characteristics of the generated ink become stable.

[0038]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on embodiments.

(Embodiment 1) FIG. 1 is a schematic view of an ink jet recording apparatus according to Embodiment 1 of the present invention.

As shown in FIG. 1, the ink jet recording apparatus 10 of this embodiment is a serial ink jet recording apparatus in which the head is scanned, and a head unit 100 provided with an ink jet head 20 for ejecting ink. It is equipped with. The head unit 100 is fixed on a carriage 11, and the carriage 11 is mounted on a pair of guide rails 12a and 12b so as to be movable in the axial direction.

A drive motor 13 is provided on one end side of the guide rails 12a and 12b, and the drive force of the drive motor 13 is applied to the pulley 14a connected to the drive motor 13 and the guide rails 12a and 12b. It is configured to be moved along a timing belt 15 that is hung between a pulley 14b provided on the other end side of the.

Further, guide rails 12a and 12b are provided on both end sides in the direction orthogonal to the carrying direction of the carriage 11.
A pair of conveying rollers 16 and 17 are provided along each of these. These transport rollers 16 and 17 transport the recording medium S below the carriage 11 in a direction orthogonal to the transport direction of the carriage 11.

Then, while the recording medium S is being fed by the transport rollers 16 and 17, the carriage 11 is scanned in the direction orthogonal to the feeding direction, so that the ink jet head 20 forms characters and images on the recording medium S. Will be recorded.

Here, an example of an ink jet head for ejecting ink will be described. 2 is an exploded perspective view of the inkjet head according to the first embodiment of the present invention, and FIG. 3 is an exploded perspective view of the head chip.
FIG. 4 is a schematic perspective view showing the assembly process of the inkjet head.

As shown in FIG. 2, the ink jet head 20 of this embodiment has a head chip 21 and a base plate 22 provided on one side of the head chip 21.
A head cover 23 provided on the other surface side of the head chip 21, and a wiring board 25 on which a drive circuit 24 for driving the head chip 21 is mounted.

First, the head chip 21 will be described in detail. As shown in FIGS. 3 and 4, the head chip 21
A plurality of chambers 28, which communicate with the nozzle openings 27 and eject ink, are arranged side by side on the piezoelectric ceramic plate 26 constituting the above. Each chamber 28 is separated by a side wall 29.

One longitudinal end of each chamber 28 extends to one end surface of the piezoelectric ceramic plate 26.
The other end does not extend to the other end surface, and the depth gradually decreases. Each chamber 28 is formed by, for example, a disk-shaped die cutter, and a portion where the depth gradually decreases is formed by using the shape of the die cutter.

In addition, the side walls 28 on both sides in each chamber 28
A pair of individual electrodes 30 to which an independent drive signal is output for each chamber 28 are formed on the surface of the opening side of the above in the longitudinal direction. The pair of individual electrodes 30 is
For example, it is formed on each sidewall 29 in each chamber 28 by known vapor deposition from an oblique direction.

Further, an ink chamber plate 31 is joined to the opening side of the chamber 28 of the piezoelectric ceramic plate 26. The ink chamber plate 31 has an ink chamber 32 which is a recess communicating with only the other shallow end of each chamber 28, and a chamber 2 from the bottom of the ink chamber 32.
An ink supply port 33 penetrating in a direction opposite to 8 is provided.

Here, in this embodiment, each chamber 28 is
Are divided into groups corresponding to inks of black (B), yellow (Y), magenta (M), and cyan (C), respectively, and the ink chamber 32 and the ink supply port 33.
Are provided for each four.

The ink chamber plate 31 is, for example,
Although it can be formed of a ceramic plate, a metal plate, or the like, it is preferable to use a ceramic plate having a similar coefficient of thermal expansion in view of deformation after joining with the piezoelectric ceramic plate 26.

A nozzle plate 34 is joined to the end surface of the piezoelectric ceramic plate 26 and the joined body of the ink chamber plate 31 where the chamber 28 is open.
A nozzle opening 27 is formed at a position of the nozzle plate 34 facing each chamber 28.

Further, the nozzle plate 34 is larger than the area of the end face where the chamber 28 of the joined body of the piezoelectric ceramic plate 26 and the ink chamber plate 31 is open. The nozzle plate 34 is formed by forming a nozzle opening 27 on a polyimide film or the like by using, for example, an excimer laser device. In addition, although not shown, the surface of the nozzle plate 34 facing the printed material is
A water-repellent film having water repellency is provided to prevent ink adhesion and the like.

In the present embodiment, the nozzle support plate 35 is arranged around the end of the bonded body of the piezoelectric ceramic plate 26 and the ink chamber plate 31 where the chamber 28 is open. This nozzle support plate 3
Reference numeral 5 is for joining to the outside of the end face of the joined body of the nozzle plate 34 to hold the nozzle plate 34 stably.

Here, the ink jet head 20 provided with such a head chip 21 will be described in detail.

As shown in FIGS. 2 and 4, the ink jet head 20 has, for example, a bonding wire or the like at the end of the piezoelectric ceramic plate 26 forming the head chip 21 opposite to the nozzle opening 27 side. A wiring pattern (not shown) connected to the pair of individual electrodes 30 is formed.

Further, the nozzle support plate 35 which is a joined body of the piezoelectric ceramic plate 26 and the ink chamber plate 31.
The base plate 22 made of aluminum on the piezoelectric ceramic plate 26 side and the ink chamber plate 3 are provided on the rear end side.
The head cover 23 on the first side is assembled. The head cover 23 is provided with an ink introduction path 36 that communicates with each of the ink supply ports 33 of the ink chamber plate 31.

Then, the base plate 22 and the head cover 23 are fixed by engaging the locking shaft 23a of the head cover 23 with the locking hole 22a of the base plate 22, and the piezoelectric ceramic plate 26 and the ink chamber plate 31 are joined by both. Hold your body.

Further, as shown in FIG. 4A, a wiring board 25 is fixed on the base plate 22 protruding to the rear end side of the piezoelectric ceramic plate 26. A drive circuit 24 having a drive IC for driving the head chip 21 is mounted on the wiring board 25, and the drive circuit 24 described later and the flexible cable are connected via an anisotropic conductive film 37. As a result, the inkjet head 20 of FIG. 4B is completed.

Further, the ink jet head 2 described above
0 is a tank holder 40 that holds an ink cartridge
And the head unit 100 is formed.

Here, an example of the tank holder 40 to which the ink jet head 20 is assembled will be described with reference to FIG. Note that FIG. 5 is a schematic perspective view showing an example of the tank holder according to the present embodiment.

As shown in FIG. 5, the tank holder 40 is
The ink cartridge has a substantially box shape with an opening on one side and can hold the ink cartridge detachably.

On the upper surface of the bottom wall of the tank holder 40,
A connecting portion 41 that connects the opening formed at the bottom of the ink cartridge and the ink introducing passage 36 is provided. The connecting portion 41 is provided, for example, for each color ink of black (B), yellow (Y), magenta (M), and cyan (C).

Further, an ink flow path (not shown) is formed in the connecting portion 41, and a filter 42 is provided at the tip of the connecting portion 41 which is an opening thereof.

The ink flow paths formed in the connecting portion 41 are formed so as to communicate with the back surface side of the bottom wall, and each ink flow path is provided on the back surface side of the tank holder 40. It communicates with a head connection port 44 that opens to the side wall of 43.

On the side surface of the tank holder 40, a head holding portion 45 for holding and fixing the above-mentioned ink jet head 20 is provided.

In such a head holding portion 45, an enclosing wall 46 which is provided upright in a substantially U shape and surrounds the drive circuit 24 provided on the wiring substrate 25, and an ink jet inside the enclosing wall 46. An engagement shaft 47 that engages with a locking hole 22b provided in the base plate 22 of the head 20 and the wiring board 25 is provided upright.

Then, the head unit 100 is completed by mounting the ink jet head 20 on the head holding portion 45 of the tank holder 40 described above. At this time, the ink introduction path 36 formed in the head cover 23 is connected to the head connection port 44 of the flow path substrate 43.

Here, the driving means for outputting the driving signal to the pair of individual electrodes 30 provided on the side wall 29 in each chamber 28 will be described in detail with reference to the driving circuit 24. Note that FIG. 6 is a schematic diagram showing the connection state of the wiring between the drive circuit and the head chip.

As shown in FIG. 6, the drive circuit 24 is connected to an external power source and an external circuit 50 including an external signal such as a print signal via an external wiring 51. As a result, the external signal is transmitted via the external wiring 51 to the external circuit 5
It is output from 0 to the drive circuit 24.

The drive circuit 24 is connected via a flexible cable 38 to a pair of individual electrodes 30 provided on the side wall 29 in each chamber 28. As a result, the external signal input to the drive circuit 24 is output as a drive signal to the pair of individual electrodes 30 in each chamber 28.

In this embodiment, the piezoelectric ceramic plate 26 forming the side wall 29 of each chamber 28 is polarized in the direction from the bottom of the chamber 28 to the ink chamber plate 31.
It is the same direction as the direction in which each side wall 29 projects toward the side.

Here, the driving method of the ink jet recording apparatus 10 will be described in detail. 7 is a cross-sectional view of the piezoelectric ceramic plate and a diagram showing drive waveforms applied to the pair of individual electrodes, FIG. 8 is a diagram for explaining details of the drive waveforms, and FIG. It is sectional drawing of a piezoelectric ceramic plate explaining movement of the side wall of both sides.

The drive waveforms 60a to 60f shown in FIG. 7 represent drive voltages applied to the pair of electrodes 30 in the chambers 28a to 28f, respectively. The drive waveform 61 indicates a drive electric field generated on the side walls 29a and 29b on both sides of the chamber 28b by the drive waveforms 60a to 60c. Further, the drive waveform 62 indicates a drive electric field generated on the side walls 29d and 29e on both sides of the chamber 28e by the drive waveforms 60d to 60f.

In the present embodiment, such a driving waveform 6
After ink droplets are ejected from the chamber 28b (nozzle opening 27) by the Nos. 1 and 62, the chambers 28b and 28e are continuously
It is designed to eject ink droplets from. That is, when ejecting ink droplets from the chamber 28b,
The chamber 28e is in a standby state where ink is not ejected,
From this standby state, ink droplets are simultaneously ejected from the chambers 28b and 28e.

Further, the driving electric field for ejecting the ink droplets of the present embodiment has a pre-driving electric field for temporarily increasing the volume in the chambers 28b, 28e and a continuous driving electric field in the chambers 28b, 28e. Discharge driving electric field that temporarily reduces the volume of The pre-driving electric field is represented by the A and E regions of the driving waveform 61 and the E region of the driving waveform 62, and the ejection driving electric field is represented by the C and G regions of the driving waveform 61 and the G region of the driving waveform 62. Has been done.

Here, it is preferable that the respective generation periods of the preliminary driving electric field and the ejection driving electric field satisfy the following relationship. That is, as shown in FIG. 8, when the pre-driving electric field generation period is x and the interval between the pre-driving electric field generation period and the ejection driving electric field generation period is y, the ejection driving electric field generation period is 2x. It is preferably a length represented by -y. As a result, each nozzle opening 27
Therefore, it is possible to satisfactorily eject ink droplets.

On the other hand, in the case where ink droplets are ejected from the chamber 28b by the ejection drive electric field represented by the C region of the drive waveform 61, in the present embodiment, the chamber 28 in the standby state is
drive waveforms 60d to 60 on the side walls 29d and 29e on both sides of e.
By e, a standby drive electric field (A to C regions of the drive waveform 62) is generated to the extent that ink droplets are not ejected from the chamber 28e.

In this embodiment, such a standby driving electric field is generated in the same direction as the preliminary driving electric field in the same direction as the preliminary driving electric field, and has a shorter generation period than the preliminary driving electric field. It is composed of a non-ejection driving electric field generated in the same direction as the ejection driving electric field corresponding to the driving electric field. The non-ejection pre-driving electric field is shown in the area A of the driving waveform 62. Further, the non-ejection drive electric field is represented by the C region of the drive waveform 62, and in the present embodiment, the chamber 28
Discharge driving electric field (driving waveform 61
The same drive electric field as the C region).

Here, the generation period of the non-ejection pre-driving electric field is 1/2 or less of the generation period of the pre-driving electric field, particularly 1 /
It is preferably 10 or less, and most preferably 1/18. Thereby, even when combined with the non-ejection driving electric field, the electric field can be generated on the predetermined side wall without erroneously ejecting the ink droplet.

The peak of the non-ejection pre-driving electric field is preferably substantially the same as the peak of the pre-driving electric field. Accordingly, the non-ejection pre-driving electric field can be easily generated only by changing the generation period of the pre-driving electric field.

The movement of the side walls on both sides of each chamber when ejecting ink will be described in detail below.

In the chamber 28b from which the ink droplets are ejected, the pre-driving voltage is applied to the pair of individual electrodes 30 in the chamber 28b in the area A of the driving waveform 60b in accordance with the input of the print signal, so that both sides of the chamber 28b can be discharged. Side walls 29a, 2
A pre-driving electric field is generated at 9b. As a result, the side walls 29a, 29b of the chamber 28b are flexibly deformed so that their substantially central portions are separated toward the outside, and the volume in the chamber 28b is temporarily increased (see FIG. 9A).

At this time, the non-ejection pre-driving voltage is applied to the pair of individual electrodes 30 in the chamber 28e, and the side walls 29d and 29e on both sides of the chamber 28e have non-ejection pre-driving whose generation period is shorter than the pre-driving electric field. A driving electric field is generated.
As a result, the side walls 29d and 29e of the chamber 28e are formed.
Also, the substantially central portion thereof is flexibly deformed so as to be separated toward the outside, and the deformation amount is the side wall 29a of the chamber 28b,
It is smaller than 29b.

Subsequently, an ejection drive voltage is applied to the pair of individual electrodes 30 provided in the chambers 28a and 28c in the C regions of the drive waveforms 60a and 60c, and the ejection drive electric fields are applied to the side walls 29a and 29b on both sides of the chamber 28b. Occurs. This causes the side walls 29a, 29b of the chamber 28b to bend and deform so that the substantially central portions of the side walls 29a, 29b approach toward the inside, and the volume inside the chamber 28b is temporarily reduced from the state where the volume is increased. Ink droplets are ejected (see FIG. 9B).

On the other hand, each side wall 29a, 2 of the chamber 28b
At the same time when the ejection driving electric field is generated in 9b, the chambers 28d and 28f are generated in the C regions of the driving waveforms 60d and 60f.
A non-ejection drive voltage equivalent to the ejection drive voltage applied to the pair of individual electrodes 30 in the chambers 28a and 28c is applied to the pair of individual electrodes 30 in the chamber 28e.
A non-ejection drive electric field is generated on the side walls 29d and 29e on both sides of the. As a result, each side wall 29 of the chamber 28e is
The volume temporarily decreases from the state where the substantially central portions of d and 29e are flexibly deformed so as to be closer to the inner side and the volume inside the chamber 28b is increased (see FIG. 9B).
At this time, the volume increase due to the non-ejection pre-driving electric field of the chamber 28e is smaller than the volume increase due to the pre-driving electric field of the chamber 28b, so that the ink filled in the chamber 28e is not ejected from the chamber 28e. Absent.

After that, the chamber 2 in which the ink droplets are ejected
8b, the pre-driving electric field and the ejection driving electric field represented by the E and G regions of the driving waveform 61 are generated on the sidewalls 29a, 29b on both sides of the chamber 8e, and the driving waveform 62 is formed on the sidewalls 29d, 29e on both sides of the chamber 28e in the standby state. Ink droplets are simultaneously ejected from the chambers 28b and 28e by generating the pre-driving electric field and the ejection driving electric field represented by the E and G regions.

As described above, when the ink droplets are ejected from the chamber 28b, the standby driving electric field (non-ejection pre-driving electric field and the non-ejection pre-driving electric field) which does not eject the ink droplets to the side walls 29d and 29e on both sides of the chamber 28e in the standby state. By generating the (non-ejection driving electric field), the chamber 28b that ejected the ink droplet and the chamber 28e in the standby state are kept in the same state when the next ink droplet is ejected. The ejection characteristics of the generated ink are substantially the same.

As described above, the standby drive electric field is generated on the side walls 29d and 29e of the chamber 28e in the standby state, so that the state of each chamber immediately before the ink droplet is ejected can be uniformly maintained. Therefore, the ink ejection characteristics of the chamber 28b that ejects ink drops continuously and the chamber 28e that ejects ink drops from the standby state are made uniform.

That is, the difference in the ink ejection characteristics between the case of ejecting a plurality of ink drops at one time and the case of ejecting a relatively small number of ink drops can be suppressed to a small level. Further, since the state of each chamber 28 at the time of ejecting ink can be kept constant, it is possible to prevent variation in ink ejection characteristics due to a difference in position of the chambers 28 in the juxtaposed direction.

Therefore, ink droplets are always ejected from each nozzle opening at a stable ejection amount and ejection speed.
It is possible to always obtain good print quality.

In the present embodiment, the standby driving electric field composed of the non-ejection preliminary driving electric field and the non-ejection driving electric field is generated on the side walls 29d, 29e of the chamber 28e in the waiting state, but it is not limited to this. Instead, for example, as shown in FIG. 10, the standby drive electric field (A of drive waveform 62) consisting of only the non-ejection preliminary drive electric field is generated by drive waveforms 60d to 60f.
.About.C area) may be generated.

In this embodiment, the standby drive electric field is generated on both side walls of the chamber in the standby state, but the invention is not limited to this, and it may be generated on at least one side wall.

Further, the standby drive electric field may be selectively generated only in the chambers in the standby state immediately before the ink is ejected, or may be generated in all the chambers in the standby state at all times.

As described above, by constantly generating the standby driving electric field in all the chambers in the standby state, it is possible to prevent the ejection failure due to the increase of the ink viscosity even in the low temperature environment. This is because when ejecting ink, the electric field is constantly deformed on the side walls 29 of all the chambers 28, so that the temperature of the ink can be raised and the viscosity of the ink can be lowered. Further, since the viscosity of the ink can be reduced by thus generating the standby driving electric field, the ink having a relatively high viscosity can be used and the selection range of the ink is widened.

Here, ink droplets were respectively ejected in the ink jet recording apparatuses of the following Examples and Comparative Examples, and the relationship between the arrangement position of chambers (nozzle openings) and the ink ejection speed was investigated. The result is shown in FIG.

(Embodiment 1) In the ink jet recording apparatus of Embodiment 1, when ink droplets are ejected from a predetermined chamber, standby drive composed of a non-ejection pre-driving electric field and a non-ejection driving electric field on the sidewall of the standby chamber. An electric field was generated.

(Embodiment 2) The ink jet type recording apparatus of Embodiment 2 generates a standby drive electric field consisting of only a non-ejection preliminary drive electric field on the side wall of the standby chamber when ejecting ink droplets from a predetermined chamber. The ink jet recording apparatus of Example 1 is the same as the ink jet recording apparatus of Example 1 except that

(Comparative Example 1) The ink jet recording apparatus of Comparative Example 1 is the same as the inkjet recording apparatus of Comparative Example 1 except that when ink droplets are ejected from a predetermined chamber, a standby driving electric field is not generated on the side wall of the standby chamber. This is the same as the ink jet recording apparatus of the first embodiment.

As shown in the graph of FIG. 11A, in the ink jet type recording apparatus of Examples 1 and 2, the difference in the ejection speed of ink droplets ejected from each nozzle opening is relatively small. On the other hand, in the ink jet recording apparatus of Comparative Example 1, only the ejection speed of the ink droplets ejected from the nozzle opening (nozzle number 1) provided on the end side of the head was ejected from the other nozzle openings. It can be seen that the ejection speed of ink droplets is clearly faster.

As is clear from this result, according to the ink jet recording apparatus of the present invention, stable ink ejection characteristics can be obtained regardless of the arrangement position of the chambers.

Next, using the ink jet recording heads of Example 1 and Comparative Example 1 described above, the ink droplet ejection amount when ink droplets were ejected from all nozzle openings, and the ink droplets from one nozzle opening The difference between the ejected amount of ink droplets and the ejected amount of ink droplets was examined. The result is shown in FIG.

As is clear from the graph of FIG. 11B, in the ink jet recording apparatus of Example 1, the case where ink droplets are ejected from all nozzles and the case where ink droplets are ejected from one nozzle opening The ink droplet ejection amounts are substantially the same regardless of the drive voltage. On the other hand, in the ink jet recording head of Comparative Example 1, when ink droplets are ejected from one nozzle opening, ink droplets are ejected at any drive voltage as compared to when ink droplets are ejected from all nozzle openings. It can be seen that the discharge amount of is decreased by 20% or more.

As is clear from these results, the ink jet recording head of the present invention provides stable ink ejection characteristics regardless of the number of ink droplets ejected at one time.

(Other Embodiments) Although one embodiment of the present invention has been described above, the present invention is not limited to such a configuration.

For example, in the above-described embodiment, the ink jet head in which the pair of individual electrodes 30 is provided on the side wall 29 in each of the chambers 28a to 28f has been described as an example. The inkjet head according to the present invention is not limited to this.

For example, as shown in FIG. 12, an ink jet head of a type in which individual electrodes 30A for independently outputting drive signals are provided on the side walls 29a to 29e of the chambers 28a to 28f may be used.

Further, for example, an ink jet head of a type in which a dummy chamber not filled with ink is provided between the chambers filled with ink may be used. In addition, this type of inkjet head
The polarization direction of the side walls on both sides of each chamber is opposite to that of the ink jet head of the type described above.

Regardless of which type of ink jet head is used, the volume of the chamber is changed to the extent that ink is not ejected by generating a standby drive electric field on the side wall of the chamber in the standby state. It is possible to obtain the same effect as that of the embodiment described above.

Further, in the above-mentioned embodiment, the serial type ink jet recording apparatus for scanning the ink jet head has been described as an example. However, the present invention is applicable to a line type ink jet recording apparatus in which the ink jet head is fixed. It can also be applied to other types of inkjet recording devices.

[0111]

As described above, according to the present invention,
Non-ejection is generated on at least one side wall of the standby chamber in which ink is not ejected, in the same direction as the drive electric field, to the extent that ink is not ejected from the standby chamber, and corresponding to the pre-driving electric field and having a generation period shorter than this pre-driving electric field. Since the standby driving electric field including at least the preliminary driving electric field is generated, each chamber when ejecting the ink is maintained in a substantially uniform state. Therefore, the ejection stability of the ink ejected from each chamber can be improved.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an ink jet recording apparatus according to a first embodiment of the invention.

FIG. 2 is an exploded perspective view of the inkjet head according to the first embodiment of the present invention.

FIG. 3 is an exploded perspective view of the head chip according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing an assembly process of the inkjet head according to the first embodiment of the present invention.

FIG. 5 is a schematic perspective view showing an example of the tank holder according to the first embodiment of the present invention.

FIG. 6 is a diagram showing a schematic configuration of the ink jet recording head according to the first embodiment of the invention.

FIG. 7 is a cross-sectional view of the piezoelectric ceramic plate according to the first embodiment of the present invention and a diagram showing drive waveforms applied to a pair of individual electrodes.

FIG. 8 is a diagram showing drive waveforms according to the first embodiment of the present invention.

FIG. 9 is a cross-sectional view of the piezoelectric ceramic plate for explaining the movement on both sides of the chamber according to the first embodiment of the present invention.

FIG. 10 is a cross-sectional view of the piezoelectric ceramic plate according to the first embodiment of the present invention and a diagram showing another example of drive waveforms applied to a pair of individual electrodes.

FIG. 11 is a graph showing ink ejection characteristics in the ink jet recording apparatus of each example and comparative example.

FIG. 12 is a diagram showing a schematic configuration of an ink jet recording apparatus according to another embodiment of the invention.

FIG. 13 is a schematic perspective view showing an outline of a head chip of an inkjet head according to a conventional technique.

FIG. 14 is a cross-sectional view showing an outline of a head chip of an inkjet head according to a conventional technique.

FIG. 15 is a cross-sectional view showing an outline of a head chip of an inkjet head according to a conventional technique.

[Explanation of symbols]

10 Inkjet recording device 20 inkjet head 21 head chips 22 Base plate 23 head cover 24 drive circuit 25 wiring board 26 Piezoelectric ceramic plate 27 nozzle opening 28, 28a to 28f chamber 29, 29a to 29e Side wall 30 pair of individual electrodes 30A individual electrode 34 nozzle plate 40 tank holder 50 External circuit 51 External wiring 60a-60f, 61, 62 drive waveform 100 head units

Claims (23)

[Claims] 1. A piezoelectric ceramic plate is provided with an ink-jet head in which a plurality of chambers communicating with a nozzle opening and filled with ink are arranged side by side, and electrodes are provided on side walls on both sides of each chamber. Ink is generated by generating a driving electric field on the side wall, which includes a preliminary driving electric field that temporarily increases the volume in the chamber and an ejection driving electric field that is continuous with the preliminary driving electric field and that temporarily decreases the volume in the chamber. In an ink jet recording apparatus for ejecting, at least one side wall of at least one standby chamber capable of ejecting ink in a chamber other than a predetermined chamber for ejecting ink,
The standby drive signal for generating a standby drive electric field that corresponds to the preliminary drive electric field, is generated in the same direction as the preliminary drive electric field, and includes at least a non-ejection preliminary drive electric field having a shorter generation period than the preliminary drive electric field, An inkjet recording apparatus comprising: a driving unit that outputs together with a driving signal that generates an electric field. 2. The ink jet recording apparatus according to claim 1, wherein the peak of the non-ejection preliminary driving electric field is substantially the same as the peak of the preliminary driving electric field. 3. The ejection drive electric field generation period according to claim 1, wherein x is a pre-drive electric field generation period and y is an interval between the pre-drive electric field and the ejection drive electric field. An ink jet recording apparatus having a length represented by 2x-y. 4. The ink jet recording apparatus according to claim 1, wherein the generation period of the non-ejection preliminary driving electric field is 1/2 or less of the generation period of the preliminary driving electric field. 5. The generation period of the non-ejection pre-driving electric field according to claim 4,
An ink jet recording apparatus characterized by being 10 or less. 6. The standby drive electric field according to claim 1, wherein the standby drive electric field includes a non-ejection drive electric field corresponding to the ejection drive electric field and generated in the same direction as the ejection drive electric field. Inkjet recording device. 7. The ink jet recording apparatus according to claim 1, wherein the standby drive electric field is generated corresponding to a standby chamber immediately before ink is ejected. 8. The ink jet recording apparatus according to claim 1, wherein the standby drive electric field is generated corresponding to all standby chambers. 9. The ink jet recording apparatus according to claim 1, wherein the standby driving electric field is generated corresponding to both sidewalls of the standby chamber. 10. The ink jet recording apparatus according to claim 1, wherein the standby drive electric field is generated corresponding to only one side wall of the standby chamber. 11. The ink jet recording apparatus according to claim 1, wherein all of the electrodes are individual electrodes to which the drive signal or the standby drive signal is independently output. 12. The pair of electrodes in the chamber, which face each other, are a pair of individual electrodes to which the drive signal or the standby drive signal is output. Inkjet recording device. 13. The dummy chamber according to claim 1, wherein a dummy chamber not filled with the ink is provided between the chambers, and the electrode is provided on a sidewall of the dummy chamber. Inkjet recording device. 14. An ink jet head having a plurality of ink-filled chambers arranged in parallel with each other on a piezoelectric ceramic plate and communicating with nozzle openings, and electrodes provided on side walls on both sides of each chamber. Ink is generated by generating a driving electric field on the side wall, which includes a preliminary driving electric field that temporarily increases the volume in the chamber and an ejection driving electric field that is continuous with the preliminary driving electric field and that temporarily reduces the volume in the chamber. In an inkjet recording method for ejecting, at least one side wall of at least one standby chamber capable of ejecting ink in a chamber other than a predetermined chamber for ejecting ink,
The standby drive signal for generating a standby drive electric field, which corresponds to the preliminary drive electric field and is generated in the same direction as the preliminary drive electric field and includes at least a non-ejection preliminary drive electric field having a generation period shorter than the preliminary drive electric field, is driven. An ink jet recording method, which is characterized in that it is output together with a drive signal for generating an electric field. 15. The ink jet recording method according to claim 14, wherein the peak of the non-ejection preliminary driving electric field is substantially the same as the peak of the preliminary driving electric field. 16. The generation period of the ejection drive electric field according to claim 14 or 15, when the generation period of the preliminary drive electric field is x and the interval between the preliminary drive electric field and the ejection drive electric field is y. An ink jet recording method, wherein the length is represented by 2x-y. 17. The method according to any one of claims 14 to 16,
An ink jet recording method, wherein the generation period of the non-ejection pre-driving electric field is 1/2 or less of the generation period of the pre-driving electric field. 18. The ink jet recording method according to claim 17, wherein the generation period of the non-ejection preliminary driving electric field is 1/10 or less of the generation period of the preliminary driving electric field. 19. The method according to any one of claims 14 to 18,
The ink jet recording method, wherein the non-ejection drive electric field includes a non-ejection drive electric field generated in the same direction as the ejection drive electric field in correspondence with the ejection drive electric field. 20. In any one of claims 14 to 19,
An ink jet recording method, wherein the non-ejection driving electric field is generated corresponding to a standby chamber immediately before ejecting ink. 21. In any one of claims 14 to 19,
An ink jet recording method, wherein the non-ejection driving electric field is generated corresponding to all standby chambers. 22. In any one of claims 14 to 21,
The ink jet recording method, wherein the non-ejection driving electric field is generated corresponding to both sidewalls of the standby chamber. 23. In any one of claims 14 to 21,
An ink jet recording method, wherein the non-ejection driving electric field is generated corresponding to only one side wall of the standby chamber.