JPH0911459A - Ink-jet recording device - Google Patents

Abstract

PURPOSE: To surely represent gradation properties without causing loss of pressure loading of ink by arranging a plurality of piezoelectric members per ink chamber along the ink chamber in a state in which the respective end faces are brought into contact with the outer surface of the partition of the ink chamber. CONSTITUTION: Four piezoelectric members 31-34 per ink chamber 23 are provided on a multilayer wiring 26 in a space region 28. These piezoelectric members 31-34 are arranged along the ink chamber 23 with the prescribed intervals in a state in which the respective end faces are brought into contact with the outer face of a partition 22 forming one side wall of the ink chamber 23. The piezoelectric members 31-34 have shapes respectively projected for the partition 22 and formed into entirely equal size. Furthermore, the piezoelectric members 31-34 are respectively applied to polorization treatment in the direction directed from the multilayer wiring 26 to the partition 22. Further, all piezoelectric members 31-34 are arranged correspondingly to the ink chamber 23.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for ejecting ink droplets according to image information and recording on a recording medium such as paper.

[0002]

2. Description of the Related Art Conventionally, an ink jet which applies a voltage to a piezoelectric member in accordance with image information to deform it, pressurizes the ink based on the deformation to eject an ink droplet from a nozzle, and prints it on a recording medium such as paper. The head is used in a recording device such as a printer.

As an ink jet head of this system,
For example, Japanese Utility Model Laid-Open No. 6-67035 discloses the one shown in FIG. This inkjet head 100
Is provided with a plurality of ink ejecting mechanisms 102 to 104 by piezo transducers in one ink chamber 101. Each of these ink ejecting mechanisms 102 to 104 has a flat plate shape facing the inside of the ink chamber 101, has different sizes, and is arranged so as to be divided into an upper portion and a lower portion of the ink chamber 101. Then, a voltage is applied to one or more of the ink ejecting mechanisms 102 to 104 selectively or simultaneously by a controller (not shown) to cause the ink to be curved and deformed, and the ink is generated in the ink chamber 101 according to the deformed ink ejecting mechanism. The ink ejection energy to be controlled is controlled in multiple stages, whereby the amount of ink ejected from the nozzle 105 is controlled in multiple stages, so that the print output has gradation.

[0004]

However, in the ink jet head 100, when the ink ejecting mechanism 102 arranged in the upper part of the ink chamber 101 and the ink ejecting mechanisms 103, 104 arranged in the lower part are simultaneously driven, the ink is ejected. The pressure wave generated due to the deformation of the ejection mechanism 102 and the pressure wave generated due to the deformation of the ink ejection mechanisms 103 and 104 interfere with each other to cause a pressure loss, which causes an ink ejection failure and causes a floor failure. It may interfere with the key expression.

Therefore, the present invention has been made to solve the above problems, and an object of the present invention is to provide an ink jet recording apparatus capable of reliably expressing gradation without causing a loss of ink pressure. .

[0006]

In order to achieve the above object, an ink jet recording apparatus of the present invention comprises a top plate having a plurality of groove-shaped recesses, and a recessed surface of the top plate covering the inside of each recess. And a thin-walled partition wall forming the ink chamber, and an outer surface of the partition wall forming one wall of the ink chamber, with each end face in contact with the partition wall.
A plurality of piezoelectric members per ink chamber, and one or more piezoelectric members are selected from the plurality of piezoelectric members according to the density of image information to apply a voltage, and the piezoelectric member to which the voltage is applied. Voltage is applied to press the ink filled in the ink chamber to eject the ink droplets from the nozzles formed in the ink chamber based on the deformation.

[0007]

In the above ink jet recording apparatus, when a voltage is applied to a plurality of piezoelectric members arranged in one ink chamber by the voltage applying means, the piezoelectric members are rapidly deformed and the partition walls are pushed by the end faces to fill the ink chambers. The ink is pressurized and ejected from the nozzle. At this time, as the piezoelectric member for applying the voltage, one or more piezoelectric members are appropriately selected by the voltage applying unit according to the density of the image information, and the amount of the ejected ink is controlled in multisteps on the recording paper. The density gradation is expressed in the image recorded in. On the other hand, when the voltage application to the piezoelectric member is released, the piezoelectric member restores and the partition also returns to the original state following this restoring operation. At this time,
Negative pressure is generated inside the ink chamber, ink is replenished, and the next ink ejection is ready.

The piezoelectric member in the above ink jet recording apparatus is arranged such that each end face is in contact with a partition wall forming one wall of the ink chamber. By arranging a plurality of piezoelectric members on one side with respect to the ink chamber in this way,
Even when two or more piezoelectric members are deformed at the same time, the pressure waves generated by the respective piezoelectric members interfere with each other to reduce the pressure loss. Further, since the piezoelectric member is separated from the ink chamber by the partition wall, the ink does not penetrate into the piezoelectric member and the resistance is not lowered.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 schematically shows the overall configuration of an inkjet recording apparatus 1 which is an embodiment of the present invention. The ink jet recording apparatus 1 is roughly classified into a power supply unit 2 having a connector 2a, a drive system 3, a mechanical controller 4, a memory 5, a controller 6, an ink supply unit 7, a scan carriage 8, and a paper feed unit. It is composed of a section 9, a case 10, and an operation panel 11. The scan carriage 8 is capable of scanning in a direction orthogonal to the paper passing direction (direction of arrow a) (front and back direction of the paper surface in FIG. 1), and inside the carriage 4 is provided for each color of black, cyan, magenta and yellow. The two inkjet heads 12 are arranged along the paper passing direction, and the ink discharge nozzles are directed downward.

As shown in FIG. 2, the ink jet head 12 has a top plate 20. This top plate 20
For example, the plate is made of a non-piezoelectric material such as alumina, and a plurality of groove-shaped recesses 21 are formed on the lower surface of the plate by dicing or the like. These recesses 21 are the top plate 2
It is formed at a predetermined pitch in the width direction of 0 and extends parallel to the depth direction of the top plate 20 (the front and back direction of the paper surface in FIG. 2). A thin film partition wall 22 made of a resin film or a metal foil having conductivity is provided on the surface of the top plate 20 on which the recess 21 is formed, and the partition wall 22 is adhered to the contact surface with the top plate 20. Then, each recess 2 covered with this partition wall 22
Ink chambers 23 are formed in the inside of each.

Both ends of the spacer 24 (only one is shown) and a plurality of internal spacers 25 are adhered and fixed to the lower surface of the partition wall 22, and a plurality of spacers corresponding to the ink chambers 23 are provided between the spacers 24, 25. A space area 28 is formed. Below the spacers 24 and 25, a film-shaped multilayer wiring 26 that constitutes a part of the voltage applying means and a substrate 27 made of a non-piezoelectric material like the top plate 20 are fixed.

On the multi-layer wiring 26 in the space area 28,
As shown in FIG. 3, four piezoelectric members 31 to 34 are provided for each ink chamber 23. These piezoelectric members 31
˜34 are partition walls 22 forming one wall of the ink chamber 23.
Are arranged at predetermined intervals along the ink chamber 23 in a state where each end surface is in contact with the outer surface of the ink. Also,
Each of the piezoelectric members 31 to 34 has a shape (for example, a rectangular parallelepiped or a cube) protruding from the partition wall 22 and is formed to have the same size. Further, the piezoelectric members 31 to 34 are each polarized in the direction from the multilayer wiring 26 toward the partition wall 22, as shown by the arrow in FIG. Incidentally, the piezoelectric members 31 to 34 are arranged corresponding to all the ink chambers 23, for example, P
It is formed by adhering a plate made of ZT piezoelectric ceramic on the multilayer wiring 26 and then cutting it into a lattice shape with a dicing saw.

The thickness of the piezoelectric members 31 to 34 is
Since the spacers 24 and 25 are formed slightly larger than the spacers 24 and 25, the partition wall 22 is shallowly pressed into the inside of the concave portion 21 forming the ink chamber 23, as shown in FIG. 2 or 3. As described above, the partition wall 22 is pushed in shallowly, which has the advantage that the partition wall 22 reliably follows the vibration of the piezoelectric members 31 to 34 and the responsiveness is improved. In addition, the piezoelectric members 31 to 34 and the partition wall 22
The contact surface with and may or may not be bonded, but if bonded using a conductive adhesive, the responsiveness is further improved. In addition,
Unlike the present embodiment, the piezoelectric member 31 is formed so that the partition wall 22 which is one wall of the ink chamber 23 has a planar shape.
~ 34 may be formed in the same thickness as each spacer 24,25. In this case, the piezoelectric member 31 to
If the partition wall 34 and the partition wall 22 are bonded together, the partition wall 22 can reliably follow the vibration of the piezoelectric members 31 to 34, and the responsiveness can be secured.

As shown in FIG. 3, a nozzle plate 35 made of, for example, a resin film having a thickness of 25 to 200 μm is adhered to the front end portion of the joined body such as the top plate 20, the partition wall 22 and the substrate 27. . This nozzle plate 35
, A plurality of nozzle holes 35a are formed corresponding to each ink chamber 23 by, for example, an excimer laser, and the formation pitch thereof is 42.3 to 254 μm (pixel density: 600 to
It is about 100 dpi). In addition, the nozzle hole 35a
Is formed in a taper shape that is wide on the ink chamber 23 side and narrow on the outer side, and this shape has the effect of making it difficult to suck bubbles into the ink chamber 23.

At the rear end surface of the top plate 20, a groove-shaped ink supply passage 36 is formed for each ink chamber 23 so as to connect the upper surface of the top plate 20 with the bottom surface of the concave portion 21 which becomes the ink chamber 23. The rear end surface of the top plate 20 also covers the ink supply passage 36,
The back plate 37 having the rear end portion of the partition wall 22 adhered thereto
Has been fixed. An ink manifold 38 is fixed to the upper rear part of the top plate 20 and covers the entire upper end opening of the ink supply path 36 across the back plate 37, and an ink tube 38a is projectingly provided on the upper part thereof.

The partition wall 22 has conductivity as described above, and is connected to the ground on the rear end side of the surface facing the multilayer wiring 26. FIG. 4 is an enlarged vertical section of the multilayer wiring 26 in the thickness direction. Inside the multilayer wiring 26, the insulating layer 40 is formed inside each of the ink chambers 23 so as to correspond to each ink chamber 23. Further, four electrode layers 41 to 44 extend in parallel. The upper and lower portions of these electrode layers 41 to 44 are also covered with the insulating films 45 and 46, respectively, but the rear end portion (left side in FIG. 4) of each of the electrode layers 41 to 44 is the insulating layer 4.
It is not covered with 0 or the like, and is connected to the controller 6 via the driver IC at this portion by a method such as wire bonding. On the other hand, the front end portions of the electrode layers 41 to 44 are exposed on the upper surface of the multilayer wiring 26, and the piezoelectric members 31 to 34 are bonded to the exposed portions by a conductive adhesive. This allows
The controller 6 can individually apply a voltage to one or two or more of the piezoelectric members 31 to 34 according to image information.

FIG. 5 shows a controller 6 which constitutes a means for applying a voltage to the piezoelectric members 31 to 34 together with the multilayer wiring 26.
And the driver IC 50, which is one ink chamber 2
Only the components corresponding to the piezoelectric members 31 to 34 arranged in No. 3 are shown. In the following description, "1" corresponds to the H level and "0" corresponds to the L level.

The controller 6 includes a CPU 51 connected to an attached host computer HC and the CPU 5
It has a bit map memory 52, a shift register 53 and a latch circuit 54 connected to 1. The shift register 53 and the latch circuit 54 both have a bit number corresponding to the maximum number of piezoelectric members that are simultaneously driven, and are connected to each other.

The driver IC 50 is composed of the piezoelectric members 3
An AND gate 50a and a switching transistor 50b corresponding to each of 1 to 34 are provided. The gate opening / closing signal GS from the CPU 51 is input to one input terminal of the AND gate 50a, and the latch data from the latch circuit 54 is input to the other input terminal. On the other hand, the output terminal of the AND gate 50a is connected to the base terminal of the transistor 50b. Also,
The drive voltage V _D from the CPU 51 is applied to the collector terminal of each transistor 50b, and the emitter terminal thereof is connected to the piezoelectric members 31 to 34 via the resistor 50c and the multilayer wiring 26, respectively.

In the controller 6 and the driver IC 50 configured as described above, image information is first input from the host computer HC to the CPU 51. C
The PU 51 develops the image information into drive data for selectively driving one or two or more piezoelectric members of the piezoelectric members 31 to 34 according to the shading of each pixel. Specifically, the drive data is expanded to "1" for the piezoelectric member to be driven and to "0" for the piezoelectric member not to be driven, and stored in the bitmap memory 52. The shift register 53 uses the clock signal CS from the CPU 51.
In response to this, the drive data in the bit map memory 52 is read out bit by bit, serially input and sequentially shifted and held between the internal registers. The CPU 51 latches the latch signal LS when the driving data for one pixel corresponding to the piezoelectric members 31 to 34 is input to the shift register 53.
Is output. The latch circuit 54 uses the latch signal LS.
In response to this, the drive data is latched and each AND gate 50a
Output to When the gate opening / closing signal GS of "1" is output from the CPU 51, "1" is output from the AND gate 50 to which the latch data of "1" is input, and "0" is output from the other AND gates 50a. To be done. As described above, since the output value '1' corresponds to the H level, only the transistor 50b to which the H level image signal RS is input to the base terminal becomes conductive, and the voltage V _D is applied to the corresponding piezoelectric member. Driven.

Actually, the ink jet head 1
The piezoelectric members 31 to 34 arranged corresponding to all the two ink chambers 23 are connected to different driver ICs 50,
In addition, the shift register 53 and the latch circuit 54 have a bit number corresponding to the number of all the piezoelectric members 31 to 34, and the drive data is processed based on the density of the image information input from the host computer HC. Will be.

Next, the ink jetting operation of the ink jet head 12 having the above structure will be described. Ink is supplied from the ink supply unit 7 (see FIG. 1) to the ink manifold 38, as shown in FIG.
Each of the ink chambers 23 is filled via 6. When the positive pulse voltage shown in FIG. 6A is applied to each of the piezoelectric members 31 to 34 by the controller 6, the multilayer wiring 26 is formed inside the pulse members.
An electric field is formed in a direction from the partition wall 22 to the partition wall 22, that is, in parallel with the polarization direction, and the piezoelectric members 31 to 34 are deformed and vibrate in a so-called thickness direction vibration mode.

The controller 6 selects one or two or more piezoelectric members out of the piezoelectric members 31 to 34 according to the density of the image information and applies a voltage. The piezoelectric members 31 to 34 to which the voltage is applied are slightly contracted and deformed in the width direction (left and right direction in FIG. 3) and expanded and deformed in the thickness direction, and the partition wall 22 is formed inside the ink chamber 23 at the upper end surface thereof. Push up to. Due to this deformation, the volume of the ink chamber 23 is rapidly reduced, and the ink filled in the ink chamber 23 is pressurized. As a result, the pressurized ink is ejected in the form of liquid droplets from the nozzle holes 35a and adheres to the recording paper (not shown) to record pixel dots.

Now, consider the case where a voltage is applied to one of the piezoelectric members 31 to 34 to eject an ink droplet. The piezoelectric members 31 to 34 have the same size and the applied voltage value, and the deformation causes the partition walls 22 to be pushed up by the same amount. However, each piezoelectric member 31-
34 are arranged at a predetermined interval along the ink chamber 23, and the distance from the arrangement position to the nozzle hole 35a is different. Due to this difference in distance, there is a difference in the amount by which the ink ejection energy generated due to the deformation of each piezoelectric member 31 to 34 is attenuated before being transmitted to the ink meniscus held in the nozzle hole 35a.
The amount of ejected ink changes. Specifically, when the piezoelectric member 31 arranged behind the ink chamber 23 as viewed from the nozzle hole 35a is deformed, the amount of ink ejected is the smallest, and the piezoelectric members 32, 33, 34 in front of the piezoelectric member 32 are ejected. The amount of ejected ink increases as each deforms.

Two of the piezoelectric members 31 to 34 are also used.
When two voltages are simultaneously applied and deformed, the ink ejection energies generated by the respective deformations are accumulated and increased, and the amount of ejected ink also increases. The amount can be varied. This point is the same when the three piezoelectric members are deformed, and all the piezoelectric members 31 to 31 are deformed.
When 4 is deformed at the same time, the amount of ink ejected becomes maximum.

FIG. 7 is a graph showing the results of an experiment for confirming the change in the amount of ejected ink depending on the number of piezoelectric members to be deformed by applying a voltage and the arrangement positions thereof. The horizontal axis of this graph shows the piezoelectric member to which a voltage is applied by a code, and the vertical axis shows the ink dot diameter (μm) attached to the recording paper. In this experiment, H5D material (width 0.09 mm, height 0.3 mm, length 3 mm) manufactured by Sumitomo Metal Industries, each piezoelectric member 31 to 34, an aramid film (thickness 6 μm) on the partition wall 22, and a sharp coating on recording paper. Paper ST-70A4, MAT-1002 manufactured by Dainippon Ink and Chemicals, Inc. was used as the ink, and the diameter of the nozzle hole 35a on the small diameter side was 25 μm. In addition, the piezoelectric member 3
A pulse voltage having a voltage value of 30 v and a pulse width of 30 μsec was applied to each of 1 to 34.

As is apparent from the graph of FIG. 7, if one or two or more piezoelectric members of the piezoelectric members 31 to 34 are appropriately selected and a voltage is applied, the ejected ink amount will be regular. It was confirmed that the diameter of the ink dots that changed and adhered on the recording paper increased almost linearly. Therefore,
If the controller 6 appropriately selects the number of piezoelectric members to which a voltage is applied and the arrangement position thereof according to the density of the image information and adjusts the pressure applied to the ink chamber 23, the amount of ink ejected from the nozzle hole 35a can be increased. Can be controlled in stages,
It was confirmed that gradation expression can be performed accurately.

When the voltage application is released after the ink is ejected as described above, the piezoelectric members 31 to 34 are restored due to their elasticity, and the partition wall 22 also returns to the original state following this. At this time, the volume of the ink chamber 23 increases, a negative pressure is generated inside, ink is replenished to the ink chamber 23 through the ink manifold 38 and the ink supply passage 36, and the next ink ejection is ready.

However, when the ink is replenished, as shown in FIG.
When the voltage is instantly turned off and the volume of the ink chamber 23 is rapidly increased like the pulse shape shown in FIG.
There is a risk that bubbles will be sucked into the ink chamber 23 from the above, and the bubbles will absorb the pressure when the next pulse voltage is applied, and hinder the ink ejection. Therefore, as shown in FIG. 6B, the piezoelectric members 31 to 34 have a pulse shape when performing a restoring operation, and the piezoelectric members 31 to 34 and the partition wall 22 are the fastest in the range in which the suction of bubbles is not generated. By returning, it is possible to prevent the above inconvenience.

Further, as shown in FIG. 6 (c) or (d), if a pulse voltage in which a rear pulse having a small voltage and a reverse polarity to the main pulse is applied is applied to the piezoelectric members 31 to 34, the main pulse is generated. The ink column extending from the nozzle hole 35a after the ink is ejected can be forcibly drawn into the ink chamber 23 by slightly increasing the volume of the ink chamber 23 by the rear pulse, thereby reducing satellite noise. it can. The reason why the falling portion of the main pulse is inclined in the pulse shape shown in FIG. 6D is the same as in the case of FIG. 6B. Further, as shown in FIG. 6E, if a rectangular pulse voltage is applied while a constant low voltage is always applied, the voltage required at the time of ink ejection can be suppressed low, and the driver cost can be reduced. . Further, as shown in FIG. 6F, if an AC component is added to the pulse voltage corresponding to the image information for one time, it is possible to make the ink run out well.

The ink jetting operation as described above is independently carried out for each ink chamber 23 according to the density of the image information, the image of several lines of nozzles is drawn by the scan of the scan carriage 8, and this operation is recorded. By repeating the processing in synchronization with the movement of the paper in the paper passing direction, an image having gradation according to the image information is recorded on the recording paper.

As described above, in the ink jet recording apparatus of this embodiment, one end is in contact with the partition wall 22 forming one wall of the ink chamber 23.
Four piezoelectric members 31 to 34 are arranged for each ink chamber 23. In this way, by disposing the plurality of piezoelectric members on one side of the ink chamber 23, even when two or more piezoelectric members are simultaneously driven, the deformation of each piezoelectric member causes the inside of the ink chamber 23 to be deformed. It is possible to reduce the pressure loss caused by the generated pressure waves interfering with each other. Further, the piezoelectric members 31 to 34 are separated from each other, and the deformation of the one piezoelectric member does not deform the other piezoelectric members via the thin-film partition wall 22. Therefore, there is no variation in the amount of ejected ink due to the occurrence of the interlocking displacement.
From these facts, according to the present embodiment, it is possible to accurately control the ink ejection amount in multiple stages according to the number of piezoelectric members to be driven and the arrangement positions thereof, to reliably perform gradation expression, and to enhance the recorded image. Image quality can be improved.

Further, since the piezoelectric members 31 to 34 are separated from the ink chamber 23 by the partition wall 22 and do not come into direct contact with the ink, the ink does not permeate to lower the resistance and a stable deformation amount can be maintained. it can.

Furthermore, since each piezoelectric member 31 to 34 has a shape (for example, a rectangular parallelepiped or a cube) protruding from the partition wall, the vibration generated during the restoring operation after deformation is damped quickly. The responsiveness is excellent, and the image forming speed can be increased.

By the way, in the above embodiment, four piezoelectric members 31 to 34 are arranged per ink chamber, but the number of piezoelectric members can be increased or decreased according to the required number of gradations. FIG.
As shown in (g) or (h), FIG.
To the piezoelectric members 31 to 34
May be applied. In this case, when the voltage is turned on, the volume of the ink chamber 23 is increased to replenish the ink, and when the piezoelectric member is restored by the voltage turned off, the ink is ejected. Here, the reason why the falling portion is inclined in the pulse shape of FIG. 6 (h) is the same as in the case of FIG. 6 (b).

Further, in the above-mentioned embodiment, each piezoelectric member 31-31.
Although the lengths of 34 in the direction along the ink chamber 23 are formed to be equal, as shown in FIG. 8, the piezoelectric members 31a to 34a may be formed to have different lengths.
By doing so, when the same voltage is applied to each of the piezoelectric members 31a to 34a and the piezoelectric members 31a to 34a are independently deformed, the ejected ink amount changes differently from the above-described embodiment (for example, when the piezoelectric member 34a is driven). Is the minimum ink amount, and the ink amount increases toward the rearward piezoelectric members 33a, 32a, 31a.), And when two or more piezoelectric members are driven at the same time, It is possible to obtain an intermediate ink amount and a larger ink amount that cannot be obtained in the above-described embodiment, and it is possible to further expand the gradation expression area.

Furthermore, as the piezoelectric members 31 to 34, a laminated piezoelectric body 47 as shown in FIG. 9 may be used. In this laminated piezoelectric body 47, a piezoelectric material is laminated in a multilayer structure of two or more layers by a known green sheet method, and a common electrode 48 electrically connected to the partition wall 22 between each piezoelectric layer and a multilayer wiring 26.
The individual electrodes 49 electrically connected to each other are alternately formed, so that a large deformation amount can be obtained according to the number of stacked layers even at the same voltage as compared with the case of a single layer. Therefore, according to the laminated piezoelectric body 47, low voltage driving becomes possible and the driver cost can be reduced. Note that, in FIG. 9, an alternate long and short dash line portion on the outer periphery of the laminated piezoelectric body 47 indicates a portion where no electrode is formed so that the common electrode 48 and the individual electrode 49 are not short-circuited.

In the above embodiment, each piezoelectric member 31 to 34 is controlled by the controller 6 and the driver IC 50.
The same voltage V _D is applied to each of the piezoelectric members 3
If a driver that can change the applied voltage for each of 1 to 34 is used, the deformation amount can be controlled for each piezoelectric member, and the change region of the ejected ink amount can be further expanded. As a result, the number of gradations can be increased and higher image quality can be achieved. Further, when driving two or more piezoelectric members, a voltage is applied to each piezoelectric member at the same time.
The piezoelectric member may be driven with a slight time difference in order from the piezoelectric member located rearward of the nozzle hole 35a. This time difference is set to the time required for the pressure wave generated by the deformation of the one piezoelectric member located further rearward to propagate forward in the ink and reach the facing position of the piezoelectric member to be driven next. By driving in this way, it is possible to efficiently accumulate the ink pressure generated by the plurality of piezoelectric members, which leads to the expansion of the change area of the ejected ink amount.
Therefore, also by this, it is possible to improve the image quality by increasing the number of gradations.

[0039]

As is apparent from the above description, in the ink jet recording apparatus of the present invention, a plurality of piezoelectric members per ink chamber have their end faces contacting the partition walls forming one wall of the ink chamber. In this state, they are arranged along the ink chamber. As described above, by disposing the plurality of piezoelectric members on one side of the ink chamber, it is possible to suppress pressure interference between the piezoelectric members. As a result, accurate multi-step control of the amount of ink ejected from the nozzles is possible, gradation can be reliably expressed, and high image quality can be achieved. Also,
Since the ink does not come into direct contact with the piezoelectric member, it is possible to maintain a stable deformation amount without lowering the resistance due to ink penetration.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an inkjet recording apparatus.

FIG. 2 is a cross-sectional view of an ink jet head in an ink chamber array direction.

FIG. 3 is a cross-sectional view of the inkjet head of FIG. 2 in a direction along an ink chamber.

FIG. 4 is a cross-sectional view of a multilayer wiring in a direction along an ink chamber.

FIG. 5 is a diagram showing a configuration example of a driver IC and a controller for applying a voltage to a plurality of piezoelectric members arranged corresponding to one ink chamber.

FIG. 6 is a diagram showing a shape of a pulse voltage applied to a piezoelectric member.

FIG. 7 is a graph showing a relationship between one or two or more piezoelectric members driven for one ink chamber and the diameter of an ink dot attached to a recording sheet.

FIG. 8 is a cross-sectional view of an inkjet head showing a modified example in which a plurality of piezoelectric members arranged in one ink chamber have different sizes.

FIG. 9 is a side view of a laminated piezoelectric body.

FIG. 10 is a diagram showing a conventional example in which one ink chamber is provided with a plurality of ink ejecting mechanisms.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inkjet recording device, 6 ... Controller (voltage application means), 12 ... Inkjet head, 20 ... Top plate, 21 ... Recessed part, 22 ... Partition, 23 ... Ink chamber, 26 ...
Multilayer wiring (voltage applying means), 27 ... Substrate, 31-34 ...
Piezoelectric member, 50 ... Driver IC (voltage applying means).

Claims (1)

[Claims] 1. A top plate having a plurality of groove-shaped recesses formed therein, a thin-film partition wall which covers the recessed surface of the top plate to form ink chambers in the respective recesses, and one of the ink chambers. A plurality of piezoelectric members per ink chamber arranged along the ink chamber in a state where each end surface is in contact with the outer surface of the partition wall forming the wall, and one of the plurality of piezoelectric members according to the density of the image information. Alternatively, two or more piezoelectric members are selected and a voltage is applied, and based on the deformation of the piezoelectric members to which the voltage is applied, the partition walls are pressed to pressurize the ink filled in the ink chamber, and the ink is formed in the nozzle formed in the ink chamber. An inkjet recording apparatus comprising: a voltage applying unit that ejects ink droplets.