JP2004358716A - Ink jet head and ink jet recorder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink jet head employing a piezoelectric element in which the piezoelectric element is bonded accurately to a base member while keeping a constant gap between piezoelectric element arrays when the piezoelectric element is bonded to a diaphragm. <P>SOLUTION: The ink jet head comprises a nozzle plate 2 arranged with two nozzles arrays in parallel, a channel plate 1 having a liquid chamber 1b corresponding to a nozzle, a diaphragm 3 for transmitting driving energy to the liquid chamber 1b, two arrays of multilayer piezoelectric elements 5 and 5 each provided with a split groove corresponding to the liquid chamber 1b and being bonded to the diaphragm 3, a base member 4 for bonding the piezoelectric elements 5 and 5, and a frame member 6 having a common ink channel 6a. A gap material 7 is inserted between the piezoelectric elements 5 and 5 arranged in parallel and the gap between the piezoelectric elements 5 and 5 is kept constant with high accuracy. Consequently, an image has a predetermined aspect ratio when the piezoelectric elements 5 and 5 are bonded to the diaphragm 3 by utilizing image processing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an ink jet head and an ink jet recording apparatus that displaces a diaphragm by driving energy generated by a piezoelectric element and ejects ink droplets from nozzles, and particularly to accurately maintain a gap between piezoelectric elements corresponding to a nozzle row. The present invention relates to a piezoelectric ink jet head and an ink jet recording apparatus that can be used.
[0002]
[Prior art]
The ink jet recording apparatus has many advantages such as low noise at the time of recording, high-speed printing, high degree of freedom of ink, easy correspondence to full-color printing, and use of inexpensive plain paper. On-demand inkjet heads, which are the mainstream of today, use a piezoelectric element as the driving means, a type that heats ink to generate bubbles, and ejects ink droplets with the pressure at that time, and uses electrostatic force for the driving means And so on.
[0003]
In general, in an ink jet recording apparatus, a plurality of members are joined by an adhesive to constitute an ink jet head. 2. Description of the Related Art As a piezo-type inkjet head using a piezoelectric element as a drive source for applying pressure to ink in a pressurized liquid chamber to eject ink droplets, for example, those described in Patent Documents 1 and 2 are known.
In the ink-jet heads described in Patent Documents 1 and 2, a piezoelectric element for applying pressure to ink in a pressurized liquid chamber to eject ink droplets is joined to a base, and an upper surface of the piezoelectric element is joined to a lower surface of a diaphragm. ing.
[0004]
The joining between the piezoelectric element and the diaphragm inevitably causes a shift in the mounting position due to a problem in processing accuracy. This displacement causes variations in the displacement amount, so that the displacement force generated by the piezoelectric element is not transmitted to the diaphragm as specified. As a result, the deformation of the diaphragm due to the displacement force generated in the liquid chamber varies, which causes a variation in ejection characteristics, which causes a deterioration in print quality.
[0005]
Patent Documents 3 and 4 disclose known examples of measures against a change in ejection characteristics due to a shift in a mounting position of a piezoelectric element in an ink jet head.
Japanese Patent Application Publication No. JP-A-2003-115125 discloses a method in which a concave portion is formed on one surface of a diaphragm and a piezoelectric element is brought into contact with the concave portion to improve positional accuracy. The element is formed by printing a dispersion of a piezoelectric material on the vibration plate, whereby the piezoelectric element is formed following the distortion of the vibration plate and the liquid chamber, and no displacement occurs.
[0006]
[Patent Document 1]
JP 2002-144590 A [Patent Document 2]
JP-A-4-345856 [Patent Document 3]
JP-A-9-99553 [Patent Document 4]
JP 2001-187448 A
[Problems to be solved by the invention]
In the case of an inkjet head using a piezoelectric element as a drive source for applying pressure to ink in the pressurized liquid chamber and ejecting ink droplets, a vibration plate for transmitting drive energy to the pressurized liquid chamber is joined to the upper part of the piezoelectric element. When joining a piezoelectric element to a diaphragm, it is required to join the piezoelectric elements with high precision so that individual parts of the piezoelectric element are arranged corresponding to individual pressurized liquid chambers. Is processed by image processing to determine the joining position.
[0008]
For this reason, it is required that the gap between the piezoelectric element rows be accurately maintained at a constant interval, and an object of the present invention is to secure a constant interval between the piezoelectric element rows.
A second object of the present invention is to provide a piezoelectric element itself with a gap material to secure a constant interval.
A third object of the present invention is to secure a constant interval by inserting another member between the piezoelectric element rows.
A fourth object of the present invention is to prevent the processing conditions from being affected by using a ceramic as the gap material.
A fifth object of the present invention is to provide a gap member provided on a base portion to maintain a constant distance between the rows of piezoelectric elements and to perform positioning at the time of joining the piezoelectric elements.
A sixth object of the present invention is to improve the efficiency of the base processing step by forming the gap member into a pin shape.
It is an object of the invention of claim 7 to make the gap material plate-shaped so that it can be easily assembled to the base.
An object of an eighth aspect of the present invention is to provide an ink jet recording apparatus having both high image quality and reliability by forming a recording apparatus using the ink jet head according to the first to seventh aspects of the present invention.
[0009]
[Means for Solving the Problems]
The invention according to claim 1 of the present invention is directed to a nozzle plate in which a nozzle row including a plurality of nozzles is arranged in parallel, a flow path plate having a plurality of pressurized liquid chambers communicating with each nozzle of the nozzle row, A vibration plate that transmits driving energy to the pressurized liquid chamber, a laminated piezoelectric element that is divided by a dividing groove corresponding to the pressurized liquid chamber and joined to the vibration plate, and a base member that joins the piezoelectric elements in parallel And a gap material for determining an interval between the piezoelectric elements arranged in parallel with each other.
[0010]
According to a second aspect of the present invention, in the inkjet head of the first aspect, the piezoelectric element has a convex portion on a common electrode side.
[0011]
According to a third aspect of the present invention, in the inkjet head of the first aspect, a gap material is inserted between the piezoelectric elements.
[0012]
According to a fourth aspect of the present invention, in the ink jet head according to the first or third aspect, the gap member is a plate-shaped ceramic member.
[0013]
According to a fifth aspect of the present invention, in the inkjet head of the first aspect, the gap member is provided on the base member.
[0014]
According to a sixth aspect of the present invention, in the inkjet head according to the first or fifth aspect, the gap member has a pin shape and a plurality of the gap members are provided on the base member.
[0015]
According to a seventh aspect of the present invention, in the ink jet head according to the first or fifth aspect, the gap member has a plate shape and is provided on the base member.
[0016]
According to an eighth aspect of the present invention, there is provided an ink jet recording apparatus which uses the ink jet head according to any one of the first to seventh aspects to eject ink droplets from nozzles according to driving energy generated by a piezoelectric element driven according to a recording signal. It is characterized by the following.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described based on examples shown in FIGS.
FIG. 1 is a sectional view showing an embodiment of an inkjet head to which the present invention is applied, and FIG. 2 is an exploded perspective view of the inkjet head shown in FIG.
The ink jet head according to the present embodiment includes a flow path plate 1 made of a silicon substrate or the like and formed with a plurality of through holes 1a and individual liquid chambers 1b serving as ink flow paths. A nozzle plate 2 having a plurality of nozzles (discharge holes) 2a formed by casting or the like is joined, and a vibration plate 3 formed by Ni electroforming or the like is joined to the lower surface of the flow path plate 1 to form a pressurized liquid chamber portion. are doing. Here, the through hole 1a formed in the flow path plate 1 and the liquid chamber 1b serving as an ink flow path communicate with each other, and the plurality of through holes 1a and the liquid chambers 1b are formed in rows. In each row, the through holes 1a are arranged so as to face each other, and are arranged so as to be shifted by a half pitch in the vertical direction with respect to the plane of FIG. Also in the nozzle plate 2, the nozzle 2 a has an arrangement corresponding to the arrangement of the liquid chamber 1 b of the flow path plate 1.
[0018]
On the lower surface of the vibration plate 3, a laminated piezoelectric element 5 is joined to a base member 4 made of metal in two rows corresponding to two rows of pressurized liquid chambers to form an actuator. The piezoelectric element 5 is made of, for example, PZT, has a division groove corresponding to the liquid chamber 1b formed in the flow path plate 1, and has a length substantially equal to the row of the liquid chambers 1b. Further, the piezoelectric element 5 has a structure in which a piezoelectric layer and an internal electrode layer are alternately laminated, every other internal electrode layer is an external electrode at both ends, an internal external electrode is used as a common electrode 5a, and an external external electrode is used. Are used as the individual electrodes 5b. A flexible flat cable 5c is connected to the individual electrode 5b, and is connected to a drive circuit (not shown). A frame member 6 having a common ink channel 6a formed outside the piezoelectric element 5 is joined to the vibration plate 3 to supply ink to each individual liquid chamber.
[0019]
In the ink jet head configured as described above, when a driving voltage is applied to the piezoelectric element 5, displacement occurs in the stacking direction of the piezoelectric element 5 (vertical direction in FIG. 1), and the vibration plate 3 is moved toward each individual liquid chamber. Due to the deformation and displacement, the volume of the liquid chamber 1b decreases, the pressure in the liquid chamber increases, and ink droplets are ejected from the nozzles 2a of the nozzle plate 2 through the communication holes formed by the through holes 1a.
[0020]
When joining the diaphragm 3 and the actuator, image processing is used as a means for positioning the piezoelectric element 5 at a predetermined position on the diaphragm 3, and a gap exists between the piezoelectric elements 5. The aspect ratio when the two rows of piezoelectric elements 5 are displayed as images has a predetermined value.
Even if the piezoelectric elements 5 are brought into close contact with each other, there is no problem in the function of the actuator, but the joining position accuracy of the liquid chambers 1b is reduced, and the effect of non-uniform discharge of the liquid in each liquid chamber 1b is exerted.
[0021]
FIG. 3 is a diagram showing two rows of piezoelectric elements arranged in parallel in the ink jet head shown in FIGS. 1 and 2, FIG. 3 (A) is a plan view, and FIG. 3 (B) is a side view.
The common electrode 5a side of the piezoelectric element 5 is formed in a convex portion, and the piezoelectric elements 5 and 5 are joined on the base member 4 so that the convex portions of the parallel piezoelectric elements 5 and 5 are in contact with each other. Is secured so that the area used for image processing has a fixed aspect ratio.
[0022]
FIG. 4 is a perspective view showing a base member and a piezoelectric element bonded on the base member.
In this example, a gap is inserted between the piezoelectric elements 5 and 5 joined in parallel on the base member 4 to secure a constant interval in a region used for image processing. As the gap material 7, a ceramic material is suitable for processing, but there is no problem with a metal or resin.
[0023]
FIG. 5 is a perspective view showing an example of a base member and a gap material.
The gap material for securing the space between the piezoelectric elements 5 and 5 joined in parallel on the base member 4 is a rod-shaped gap material 8, which is inserted into the base member 4 so that the space between the piezoelectric elements 5 is constant. This is an example in which the position of the piezoelectric element 5 is also maintained when the piezoelectric element 5 is joined.
[0024]
FIG. 6 is a perspective view showing different examples of the base member and the gap member.
The gap material for securing the space between the piezoelectric elements 5 and 5 joined in parallel on the base member 4 is a plate-like gap material 9 and inserted into the base member 4 to keep the space between the piezoelectric elements 5 constant. In addition, this is an example in which positioning at the time of joining the piezoelectric element 5 is also performed.
[0025]
Next, an ink jet recording apparatus including at least one ink jet head having the above-described configuration will be described.
FIG. 7 is a perspective view showing a main part of the ink jet recording apparatus of the present invention, and FIG. 8 is a side sectional view showing a main part of the same ink jet recording apparatus.
[0026]
The ink jet recording apparatus according to the present embodiment includes a carriage 23 movable in the main scanning direction inside a recording apparatus main body 11, a recording head 24 including an inkjet head mounted on the carriage 23, and an ink cartridge 25 for supplying ink to the recording head 24. A paper cassette (or paper tray) 14 capable of loading a large number of papers 13 from the front side is detachably attached to a lower portion of the apparatus main body 11. The manual feed tray 15 for manually feeding the paper 13 can be opened, and the paper 13 fed from the paper feed cassette 14 or the manual feed tray 15 can be taken in. After the required image is recorded, the sheet is discharged to the sheet discharge tray 16 mounted on the rear side.
[0027]
The printing mechanism unit 12 slidably holds the carriage 23 in the main scanning direction (the direction perpendicular to the plane of FIG. 8) by a main guide rod 21 and a sub guide rod 22, which are guide members that are laterally mounted on left and right side plates (not shown). On the carriage 23, a recording head 24 composed of an ink jet head for discharging ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk) is scanned by a plurality of ink discharge ports. They are arranged in a direction crossing the direction, and are mounted with the ink droplet ejection direction facing downward. Each ink cartridge 25 for supplying each color ink to the recording head 24 is exchangeably mounted on the carriage 23.
[0028]
The ink cartridge 25 has an air port that communicates with the atmosphere above, a supply port that supplies ink to the recording head 24 composed of an inkjet head below, and a porous body filled with ink inside. The ink supplied to the recording head 24 is maintained at a slight negative pressure by the capillary force of the material.
[0029]
In addition, although the heads of the respective colors are used here as the recording heads 24, a single head having nozzles for ejecting ink droplets of the respective colors may be used. In addition, the ink jet head used as the recording head 24 in the present invention is of a piezo type in which ink is pressurized through a vibration plate forming a liquid chamber wall by an electromechanical transducer made of a piezoelectric element.
[0030]
The carriage 23 is slidably fitted to the main guide rod 21 on the rear side (downstream side in the paper transport direction), and is slidably mounted on the front guide side (downstream side in the paper transport direction) on the sub guide rod 22. . In order to move and scan the carriage 23 in the main scanning direction, a timing belt 30 is stretched between a driving pulley 28 and a driven pulley 29 which are driven to rotate by a main scanning motor 27. , And the carriage 23 is reciprocated by the forward and reverse rotation of the main scanning motor 27.
[0031]
On the other hand, in order to transport the sheet 13 set in the sheet cassette 14 to the lower side of the recording head 24, the sheet 13 is guided by a sheet feed roller 31 and a friction pad 32 for separating and feeding the sheet 13 from the sheet cassette 14. A guide member 33 for carrying the sheet 13, a conveying roller 34 for turning over the conveyed sheet 13 and conveying the sheet 13, a conveying roller 35 pressed against the peripheral surface of the conveying roller 34, and a feed angle of the sheet 13 from the conveying roller 34 are defined. A tip roller 36 is provided. The transport roller 34 is driven to rotate by a sub-scanning motor 37 via a gear train.
[0032]
Further, there is provided a printing receiving member 40 which is a paper guide member for guiding the paper 13 sent from the transport roller 34 below the recording head 24 in accordance with the moving range of the carriage 23 in the main scanning direction. On the downstream side of the printing receiving member 40 in the paper transport direction, there are provided a transport roller 41 and a spur 42 that are driven to rotate in order to transport the paper 13 in the paper discharge direction, and a paper discharge that transports the paper 13 to the paper discharge tray 16. Rollers 43 and spurs 44 and guide members 45 and 46 forming a paper discharge path are provided.
[0033]
At the time of recording, the recording head 24 is driven in accordance with an image signal while moving the carriage 23, thereby discharging ink on the stopped paper 13 to record one line, and after transporting the paper 13 by a predetermined amount, the next time. Record the line. Upon receiving a recording end signal or a signal indicating that the rear end of the sheet 13 has reached the recording area, the recording operation is terminated and the sheet 13 is discharged.
[0034]
In addition, a recovery device 47 for recovering the ejection failure of the head 24 is disposed at a position outside the recording area on the right end side in the moving direction of the carriage 23. The recovery device 47 has cap means, suction means and cleaning means. The carriage 23 is moved to the recovery device 47 side during standby for printing, the recording head 24 is capped by the capping means, and the ejection opening portion is kept in a wet state, thereby preventing ejection failure due to ink drying. In addition, by ejecting ink that is not related to printing during printing or the like, the ink viscosity of all the ejection ports is kept constant, and stable ejection performance is maintained.
[0035]
In the event of a discharge failure, for example, the discharge port of the recording head 24 is sealed by a capping means, air bubbles and the like are sucked out of the discharge port by a suction means through a tube, and ink and dust adhered to the discharge port surface are cleaned. The ejection failure is recovered by the means. The sucked ink is discharged to a waste ink reservoir (not shown) provided at a lower portion of the main body, and is absorbed and held by an ink absorber inside the waste ink reservoir.
[0036]
【The invention's effect】
As apparent from the above description, the present invention has the following effects.
In the inkjet head according to the first aspect, when the piezoelectric element is bonded to the vibration plate, the gap between the parallel piezoelectric elements can be set to a predetermined value, and the positioning of the piezoelectric element and the base member can be performed using image processing. Can be performed with high accuracy.
[0037]
In the inkjet head according to the second aspect, the convex shape is provided on the common electrode side of the multilayer piezoelectric element, so that when the two rows of piezoelectric elements are joined in parallel on the base member, the convex shapes are brought into contact with each other to perform image processing. Can be secured with high accuracy.
[0038]
In the ink jet head according to the third and fourth aspects, a gap necessary for image processing can be secured by inserting a gap material between the stacked piezoelectric elements arranged in parallel. Further, by using a ceramic material for the gap material, it is possible to prevent the processing conditions from being affected when processing the multilayer piezoelectric element.
[0039]
In the ink jet head according to the fifth aspect, by providing the gap member on the base member, the interval between the parallel piezoelectric elements required for image processing can be secured. Further, the gap material can be used for positioning at the time of joining the laminated piezoelectric element.
[0040]
In the ink jet head according to the sixth aspect, when the gap member is formed at the same time as the base member is processed, the number of processing steps increases. Therefore, the efficiency of the processing process can be improved by inserting the bar-shaped gap material later. .
[0041]
In the ink jet head according to the seventh aspect, the gap member is formed in a plate shape, so that the gap member can be easily assembled to the base member.
[0042]
In the ink jet recording apparatus according to the eighth aspect, the recording apparatus having the ink jet head having uniform ejection characteristics according to the first to seventh aspects can provide a recording apparatus having high image quality and high reliability. it can.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an embodiment of an ink jet head to which the present invention is applied.
FIG. 2 is an exploded perspective view of the inkjet head shown in FIG.
3A and 3B are diagrams showing two rows of piezoelectric elements arranged in parallel in the ink jet head shown in FIGS. 1 and 2, wherein FIG. 3A is a plan view and FIG. 3B is a side view.
FIG. 4 is a perspective view showing a base member and a piezoelectric element bonded on the base member.
FIG. 5 is a perspective view showing an example of a base member and a gap member.
FIG. 6 is a perspective view showing different examples of a base member and a gap member.
FIG. 7 is a perspective view showing a main part of the ink jet recording apparatus of the present invention.
8 is a side sectional view showing a main part of the ink jet recording apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Flow path plate, 1a ... Through-hole, 1b ... Liquid chamber, 2 ... Nozzle plate, 2a ... Nozzle (discharge hole), 3 ... Vibration plate, 4 ... Base member, 5 ... Piezoelectric element, 5a ... Common electrode, 5b ... individual electrodes, 5c ... flexible flat cable, 6 ... frame member, 6a ... common ink flow path, 7 ... gap material, 8 ... rod-shaped gap material, 9 ... plate-shaped gap material, 11 ... recording device body, 12 ... printing mechanism Reference numeral 13: paper, 14: paper feed cassette, 15: manual feed tray, 16: discharge tray, 21: main guide rod, 22: slave guide rod, 23: carriage, 24: recording head, 25: ink cartridge, 27 ... Main scanning motor, 28 ... Drive pulley, 29 ... Driving pulley, 30 ... Timing belt, 31 ... Paper feed roller, 32 ... Friction pad, 33 ... Guide member, 34 ... Transport roller, 35 ... Transport B, 36: tip roller, 37: sub-scanning motor, 40: print receiving member, 41: transport roller, 42: spur, 43: discharge roller, 44: spur, 45, 46: guide member, 47: recovery device .

Claims (8)

A nozzle plate having a plurality of nozzle rows arranged in parallel, a flow path plate having a plurality of pressurized liquid chambers communicating with each nozzle of the nozzle row, and a vibration transmitting drive energy to the pressurized liquid chambers A plate, a laminated piezoelectric element divided by a dividing groove corresponding to the pressurized liquid chamber and joined to the diaphragm, and a base member joining the piezoelectric elements in parallel. An ink jet head having a gap material for determining an interval between piezoelectric elements. The inkjet head according to claim 1, wherein the piezoelectric element has a convex portion on a common electrode side. The inkjet head according to claim 1, wherein a gap material is inserted between the piezoelectric elements. The inkjet head according to claim 1, wherein the gap member is a plate-shaped ceramic member. The inkjet head according to claim 1, wherein the gap member is provided on the base member. The inkjet head according to claim 1, wherein the gap member has a pin shape, and a plurality of the gap members are provided on the base member. The inkjet head according to claim 1, wherein the gap member has a plate shape, and is provided on the base member. An ink jet recording apparatus using the ink jet head according to any one of claims 1 to 7, wherein ink droplets are ejected from nozzles according to driving energy generated by a piezoelectric element driven in accordance with a recording signal.

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