JPH11254669A - Ink jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance a nozzle density without increasing in size. SOLUTION: The ink jet head comprises a plurality of drivers 219 arranged in one surface, and a plurality of corresponding ink channels 211 of the drivers 219. The drivers 219 contains first drivers for driving the channels 211 of a first direction as seen from one surface of the plurality of the channels 211, and second drivers 219 for driving the channel 211 of a second direction of a reverse direction from the first direction as seen from the one surface of the channels 211.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ink jet head used in an ink jet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, ink is stored in an ink channel, and the ink in the ink channel is pressurized by utilizing the deformation of the piezoelectric element caused by applying a voltage to the piezoelectric element. There is known an ink jet head that ejects ink from a nozzle communicating with the ink jet head.

In this ink jet head, a plurality of ink jet units for ejecting ink are provided so that ink is superimposed and recorded at the same position on a recording sheet, and a number of inks such as yellow (Y), magenta (M), and cyan (C) are recorded. Normally, a full-color image can be recorded by ejecting color inks and mixing the colors.

Here, a conventional ink jet head will be described with reference to FIGS. FIG. 11 is a plan view showing a part of a surface having nozzles of an inkjet unit in a conventional inkjet head. 12 is a sectional view taken along line FF of FIG. 11, and FIG. 13 is a sectional view taken along line GG of FIG.
FIG. 14 is a sectional view taken along line HH of FIG. 11. In the drawings, the same reference numerals indicate the same or corresponding members.

Referring to these drawings, the ink jet unit 200 includes a channel plate 301 and a partition 30.
3, the individual electrode side wiring portion 318, the diaphragm 305, the common electrode side wiring portion 317, and the substrate 307 are integrally laminated, and the nozzle plate 306 is attached from the side (the left side in FIG. 12). .

A plurality of ink channels 31 for accommodating ink are provided between the channel plate 301 and the partition wall 303.
1 and each ink channel 311 is connected to an ink common chamber 313.
And an ink common chamber 313 for supplying ink to the ink channel 311 via the inlet 315 are formed. Common ink chamber 313
Is connected to an ink tank (not shown), and receives supply of ink from the ink tank.

[0007] The vibration plate 305 has each ink channel 3
11 corresponding to the driving piezoelectric element 319 and the piezoelectric element pillar 3
21, the driving piezoelectric element 319 and the piezoelectric element pillar 3
21 is separated by a separate groove 320.

The common electrode side wiring portion 317 between the substrate 307 and the driving piezoelectric element 319 is connected to the ground, and the individual electrode side wiring portion 318 between the partition wall 303 and the driving piezoelectric element 319 is connected to the head discharge. Connected to drive unit. The common electrode side wiring section 317 is connected to a common electrode in the driving piezoelectric element 319, and the individual electrode side wiring section is connected to the driving piezoelectric element 3.
19 are connected to the individual electrodes.

The operation of the ink-jet unit having such a configuration is controlled by the control unit of the ink-jet printer, a voltage is applied between the common electrode side wiring portion 317 and the individual electrode side wiring portion 318, and the driving piezoelectric element 319 is driven. Is deformed in the direction in which the partition wall 303 is pushed. The deformation of the driving piezoelectric element 319 is transmitted to the partition wall 303, whereby the ink in the ink channel 311 is pressurized, and the ink drop flies toward the recording sheet via the nozzle 312.

In order to improve the performance of the ink jet head, a method is known in which two ink jet units 300 are used to arrange the nozzles in a staggered arrangement. This is 2
The two ink jet units 300 are arranged by being shifted by a half of the nozzle interval, and the nozzle density is doubled by staggering the nozzles.

FIG. 15 shows two ink jet units 3
FIG. 3 is a plan view of a surface having nozzles of an inkjet head when the nozzles are arranged in a staggered pattern using 00. According to this, for example, if two inkjet heads having a nozzle density of 180 [dpi] are used, the nozzle density 360
[Dpi] inkjet head.

[0012]

However, in order to improve the performance of the ink jet head, it is necessary to increase the nozzle density by narrowing the interval between nozzles in order to make the dots printed on the recording sheet finer. In order to increase the nozzle density of the inkjet unit 300 described above, there are structural problems due to the necessity of securing the volume of the ink channel 311 and difficulty in processing the diaphragm 305.

In the method of using two ink jet units 300 to form a staggered arrangement of nozzles, since only two ink jet units 300 are used, there is a problem that the ink jet head becomes large and the weight also increases. Since the inkjet head moves on a recording medium during recording, it is required to reduce the size and weight in order to simplify a mechanism for moving the inkjet head.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an ink jet head having an increased nozzle density without increasing the size.

Still another object of the present invention is to provide an ink jet head having a simple structure and easy manufacture.

[0016]

According to one aspect of the present invention, an ink jet head having a plurality of driving units arranged in one plane and a plurality of ink channels respectively corresponding to the plurality of driving units. Wherein the plurality of driving units are a first driving unit that drives an ink channel in a first direction when viewed from one surface of the plurality of ink channels, and one surface of the plurality of ink channels. And a second driving unit that drives an ink channel in a second direction opposite to the first direction as viewed from above.

According to the present invention, it is possible to provide an ink jet head having an increased nozzle density without increasing the size.

More preferably, the plurality of driving units arranged in one plane are integrally formed as one vibration plate, and one vibration plate is provided with an electrode and is a part which operates as a plurality of driving units. And a portion that divides each of the plurality of driving units by not forming an electrode.

According to the present invention, it is possible to provide an ink jet head having a simple structure and easy manufacture.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An ink jet head according to a first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing a schematic configuration of an ink jet printer to which an ink jet head according to a first embodiment of the present invention is applied.

The ink jet printer 1 includes a recording sheet 2 as a recording medium such as paper or a plastic thin plate, an ink jet head 3 as an ink jet printer head, a carriage 4 holding the ink jet head 3, and a recording sheet. Sliding shafts 5 and 6 for reciprocating in parallel with the recording surface of the recording medium 2 and a drive motor 7 for reciprocatingly driving the carriage 4 along the sliding shafts 5 and 6
And a timing belt 9 for changing the rotation of the drive motor 7 into a reciprocating motion of the carriage, and an idle pulley 8.

In addition, the ink jet printer 1 prevents the recording sheet 2 from floating by suppressing the recording sheet 2 between the platen 10 and the platen 10 which also serves as a guide plate for guiding the recording sheet 2 along the conveyance path. The paper press plate 11, the discharge roller 12 for discharging the recording sheet 2, the spur roller 13, and the recovery system 14 for cleaning the nozzle surface of the printer head 3 which discharges ink and recovering the ink discharge amount to a good state. And a paper feed knob 15 for manually conveying the recording sheet 2.

The recording sheet 2 is fed to a recording section where the ink jet head 3 and the platen 10 face each other by a sheet feeding device such as a manual feed or a cut sheet feeder. At this time, the rotation amount of a paper feed roller (not shown) is controlled, and the conveyance to the recording unit is controlled.

The ink jet head 3 has a piezoelectric element (P
ZT) is used. A voltage is applied to the piezoelectric element,
Distortion occurs. This distortion changes the volume of the ink channel filled with ink. Due to this change in volume, ink is ejected from nozzles provided in the ink channel, and recording on the recording sheet 2 is performed. This will be described in detail later.

The carriage 4 performs a main scan of the recording sheet 2 in the traverse direction (a direction crossing the recording sheet 2) by the driving motor 7, the idle pulley 8, and the timing belt 9,
The inkjet head 3 mounted on the carriage 4 records an image for one line. Each time recording of one line is completed, the recording sheet 2 is fed in the vertical direction and is sub-scanned to record the next line.

The image is recorded on the recording sheet 2 in this manner. The recording sheet 2 that has passed through the recording unit is discharged by a discharge roller 12 disposed downstream of the recording sheet in the transport direction and a spur roller 13 pressed against the discharge roller 12.

FIG. 2 is a block diagram showing a schematic configuration of the control unit of the ink jet printer 1. As shown in FIG.

The control unit of the ink jet printer 1 is C
PU 101, RAM 102, ROM 103, data receiving unit 104, head ejection driving unit 105, head movement driving unit 106, paper feed driving unit 107, recovery motor driving unit 108, and various sensor units 109 Contains.

The CPU 101 for controlling the whole executes a program stored in the ROM 103 by using the RAM 102 as necessary. This program controls the head ejection drive unit 105, the head movement drive unit 106, the paper feed drive unit 107, and various sensor units 109 based on the image data read from the data reception unit 104, A part for recording an image and a part for controlling the recovery system motor drive unit 108 and various sensor units 109 when necessary to recover the nozzle surface of the inkjet head 3 to a good state are included.

The data receiving unit 104 is connected to a host computer or the like, and receives image data to be recorded.

Under the control of the CPU 101, the head ejection drive unit 105 drives the piezoelectric elements of the ink jet head 3, and the head movement drive unit 106 drives the drive motor 7 that moves the carriage 4 holding the ink jet head 3 in the column direction. , And the paper feed drive unit 107 drives the paper feed roller. Also, based on the control of the CPU 101,
The recovery system motor drive unit 108 includes the inkjet head 3
A motor and the like necessary for restoring the nozzle surface to a good state are driven.

FIGS. 3 to 8 are views for explaining the structure of the ink-jet unit 200 of the ink-jet head 3. FIG. FIG. 3 is a plan view illustrating a part of the surface of the inkjet unit 200 having the nozzle 212. FIG.
3 is a sectional view taken along line AA of FIG. 3, FIG. 5 is a sectional view taken along line BB of FIG. 3, and FIG. 6 is a sectional view taken along line CC of FIG. 7 is a sectional view taken along line DD of FIG. 4, and FIG. 8 is a sectional view taken along line EE of FIG.

The ink jet unit 200 has a structure in which channel plates 201 and 202, partition walls 203 and 204, and a vibration plate 205 are integrally laminated, and a nozzle plate 206 is attached from the side (left direction in FIG. 4).

The nozzle plate 206 is made of a metal such as nickel or a synthetic resin such as polyimide, and has a nozzle 212.

The nozzle 212 is formed by electroforming or pressing when the nozzle plate 206 is made of metal such as nickel, and by laser processing when the nozzle plate 206 is made of synthetic resin such as polyimide. The inner diameter of the nozzle 212 is determined by the diameter of the ink drop to be ejected.
[Μm].

The channel plates 201 and 202 are formed by etching a plurality of ink channels 211 by etching stainless steel (SUS) or nickel (Ni).
And the ink common chambers 213 and 214 and an inlet 215 connecting each ink channel 211 to the ink common chambers 213 and 214. At this time, the ink channel 21
1 and the depth of the ink common chambers 213 and 214 are determined by the pressure applied in the ink channel 211, etc.
In this embodiment, the thickness is set to 200 [μm].

The partition walls 203 and 204 are made of stainless steel (S
US) or nickel (Ni) with a thickness of about 10 [μ
m].

Each ink channel 2 is provided on the diaphragm 205.
11 includes a plurality of driving piezoelectric elements 219 corresponding to 11, a common electrode side wiring portion 217 and an individual electrode side wiring portion 218.
In the processing of the vibration plate 205, first, the piezoelectric element is fixed to the common electrode side wiring portion 217 formed on the partition wall 203, and then the separate groove 220 is formed by dicer processing to separate the piezoelectric element. This is performed by forming the individual electrode side wiring portion 218.

Further, by this division, the driving piezoelectric elements 219 corresponding to the respective ink channels 211 and the wall 216 surrounding them are separated.

One end of the common electrode side wiring portion 217 is connected to all the driving piezoelectric elements 2 in the ink jet unit 200.
19 is connected to a common ground, and the other end is connected to a common electrode in all the driving piezoelectric elements 219. One end of the individual electrode side wiring section 218 is connected to the head ejection driving section 105 of the inkjet printer 1, and the other end is connected to an individual electrode in each driving piezoelectric element 219.

The channel plates 201 and 202, the partition walls 203 and 204, the vibration plate 205, and the nozzle 212 are bonded together with an adhesive (AZ-15 or the like) which is not affected by ink, and the nozzle plate 206 connects the nozzle 212 to the ink channel 211. Pasted according to the position. The thickness of the adhesive layer in the present embodiment is about 2 to 3 [μm].

The operation of the ink jet unit 200 having such a configuration is controlled by the head discharge drive unit 105 of the ink jet printer 1. A predetermined voltage, which is a print signal, is applied between the common electrode side wiring portion 217 and the individual electrode side wiring portion 218 from the head ejection driving portion 105, and the driving piezoelectric element 219
Deforms in the direction of pressing. The deformation of the driving piezoelectric element 219 is transmitted to the partition wall 203 or 204, whereby the ink in the ink channel 211 is pressurized and the nozzle 2
The ink drop flies toward the recording sheet 2 via the recording sheet 2.

Referring to FIG. 6, ink common chamber 214 is connected to an ink tank (not shown), and ink is supplied from the ink tank. The ink in the ink common chamber 214 is supplied to the ink channel 2 via the inlet 215.
11 is supplied. Similarly, the ink common chamber 213 in the channel plate 201 is connected to the ink tank.

Referring to FIG. 7, driving piezoelectric element 219
Are arranged in a row in contact with the partition wall 203. Ink channel 21 formed in channel plate 201
1 is arranged on the side opposite to the driving piezoelectric element 219 when viewed from the partition wall 203. The ink channels 211 formed in the channel plate 202 are arranged on the same side as the driving piezoelectric elements 219 when viewed from the partition wall 203. Further, the driving piezoelectric elements 219 corresponding to the ink channels 211 formed on the channel plate 201 and the driving piezoelectric elements 219 corresponding to the ink channels 211 on the channel plate 202 side are alternately arranged.

In other words, the ink jet unit 20
0 indicates that the driving piezoelectric elements 219 and the ink channels 211 are arranged such that the adjacent driving piezoelectric elements 219 correspond to the ink channels 211 formed on the different channel plates 201 and 202.

The space is reduced by using a piezoelectric element conventionally used as a pillar member as a driving piezoelectric element for pressurizing ink in the ink channel 211.

Here, the reaction force generated by the deformation of the driving piezoelectric element 219 will be described. Driving piezoelectric element 219
When the ink is deformed to pressurize the ink in the ink channel 211 on the nozzle plate 201 side, the partition wall 203 is pushed, and the reaction force acts on the partition wall 204. The channel plate 202 supporting the partition wall 204 is partially thick because the ink channel 211 is not formed at the position where the reaction force acts. Therefore, channel plate 2
02 can maintain sufficient rigidity to support the reaction force.

Similarly, when the driving piezoelectric element 219 is deformed and pressurizes the ink in the ink channel 211 on the channel plate 202 side, the channel plate 201 is pressed.
Since the ink channel 211 is not formed at the position where the reaction force acts, sufficient rigidity to support the reaction force can be maintained.

Further, the channel plates 201, 20
If the surface 223 opposite to the second diaphragm 205 is fixed by another member, for example, another ink jet unit 200 or the like, the deformation of the channel plates 201 and 202 can be prevented. Thus, crosstalk caused by deformation of the channel plates 201 and 202 can be reliably prevented.

In the ink jet head 3 shown in this embodiment, since the ink jet unit 200 is configured as described above, the nozzle density can be doubled while maintaining the ink flying performance of the conventional ink jet head, and , And can be downsized. Further, since the piezoelectric element is not used as the column member, the piezoelectric element can be effectively used, and the material cost can be reduced.

[Second Embodiment] Next, a second embodiment will be described. The inkjet head 3 according to the second embodiment has a configuration in which a plurality of driving piezoelectric elements 219 are provided in the inkjet unit 200 of the inkjet head 3 according to the first embodiment. In the second embodiment, the driving piezoelectric element 21
Since the configuration is the same as that of the first embodiment except for No. 9, the description will not be repeated here.

FIG. 9 is a sectional view of an ink jet unit 200 of the ink jet head 3 according to the second embodiment.

Referring to the figure, diaphragm 205 is formed by laminating piezoelectric elements. Electrode 221 is formed by laminating electrodes between piezoelectric elements, and a piezoelectric element is laminated without electrodes. And a void portion 222 which is laminated. The gaps and the electrodes are alternately arranged, and the gaps divide the electrode. Diaphragm 205 does not have a separate groove between electrode portion 221 and gap portion 222. The electrode part 221 is located at a position facing the ink channel 211, and a gap 222 is provided between the electrode parts 221.

FIG. 10 is a view showing a part of a cross section taken along line II of FIG. 9, and is a view showing a cross section of the electrode portion 221 of the diaphragm 205. Referring to the drawing, driving piezoelectric elements 219 are alternately stacked so that the polarities are reversed. The common electrode 224 and the individual electrode 225 are alternately inserted between the driving piezoelectric elements 219, and the common electrode 224 is connected to the common electrode side wiring portion 217, and the individual electrode 225 is connected to the individual electrode side wiring portion 218. Have been. Note that the common electrode 224 and the individual electrode 225 are not stacked in the gap 222.

Since the diaphragm 205 is configured as described above,
When a voltage is applied between the common electrode side wiring portion 217 and the individual electrode side wiring portion 218, only the electrode portion 221 is deformed by the piezoelectric effect, and the gap portion 222 is not deformed.

Therefore, a force is applied in the direction of pushing the partition 203 or 204 by the deformation of the electrode portion 221,
The partition 203 or 204 is deformed. As a result, the ink in the ink channel 211 is pressurized,
2, the ink drop flies toward the recording sheet 2.

According to the ink jet head 3 of this embodiment, the following effects can be obtained in addition to the same effects as those of the ink jet head 3 shown in the first embodiment.

In the ink jet head 3 according to the present embodiment, since the electrode portion 221 and the gap portion 222 are not separated by the separate groove, the gap portion 222 plays a role of maintaining the distance between the partition walls 203 and 204. . Thus, the channel plate 201 or the channel plate 2 due to the deformation of the electrode portion 2221 adjacent to the gap portion 222
02 can be prevented from being deformed.

Further, since it is not necessary to separate the electrode portion 221 from the gap portion 222 by a separate groove, the inkjet head 3 can have a simple structure, and the inkjet head 3 can be easily manufactured.

The embodiments disclosed this time are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a circuit configuration of an inkjet printer to which an inkjet head according to a first embodiment of the present invention is applied.

FIG. 2 is a block diagram of a control circuit of the inkjet printer of FIG.

FIG. 3 is a plan view of the inkjet unit 200.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a sectional view taken along line BB of FIG. 3;

FIG. 6 is a sectional view taken along line CC of FIG. 3;

FIG. 7 is a sectional view taken along line DD of FIG. 4;

FIG. 8 is a sectional view taken along line EE of FIG. 4;

FIG. 9 is a sectional view of an inkjet unit of an inkjet head according to a second embodiment of the present invention.

FIG. 10 is a sectional view of a diaphragm.

FIG. 11 is a plan view of a conventional ink jet unit.

FIG. 12 is a sectional view taken along line FF of FIG. 11;

13 is a sectional view taken along line GG of FIG.

FIG. 14 is a sectional view taken along line HH of FIG. 11;

FIG. 15 is a plan view when nozzle density is doubled using two conventional inkjet units.

[Explanation of symbols]

 200 inkjet unit 201, 202 channel plate 203, 204 partition wall 205 vibration plate 206 nozzle plate 211 ink channel 212 nozzle 219 piezoelectric element 221 electrode section 222 void section

Claims (2)

[Claims] 1. An inkjet head comprising: a plurality of driving units arranged in one plane; and a plurality of ink channels corresponding to each of the plurality of driving units, wherein the plurality of driving units are: A first driving unit that drives an ink channel in a first direction when viewed from the one surface of the plurality of ink channels; and a first driving unit that drives the ink channel from among the plurality of ink channels when viewed from the one surface. A second driving unit that drives an ink channel in a second direction opposite to the first direction. 2. The plurality of driving units arranged in one plane are integrally formed as one diaphragm, and the one diaphragm is formed with electrodes and operates as the plurality of driving units. The inkjet head according to claim 1, further comprising a portion and a portion that divides each of the plurality of driving units by not forming an electrode.