JPH0655734A - Ink jet printing head and ink jet printer - Google Patents

Abstract

PURPOSE:To ensure that ink discharging properties are stabilized, print quality is improved, noise generation is minimized and the life of a head is prevented from becoming short. CONSTITUTION:The subject ink jet printing head consists of pressure chambers 2a to 2n arranged in parallel in right and left rows, a common ink passage which communicates with each pressure chamber, a substrate 1 where the common ink passage and an ink introduction aperture which supplies ink to the common ink passage are formed, nozzles formed penetrating through the substrate in a linear shape at an end where pressure chambers 2a to 2n stack over the other in right and left rows, an oscillation plate 7 installed on the pressure chamber-formed area of the substrate 1 and piezoelectric elements 8a to 8n attached to the outer surface of the oscillation plate positioned against the pressure chambers 2a to 2n. In addition, a piezoelectric head unit with flexible cables 9a, 9b which connect each pressure chamber to a signal generating source, is installed on the base of the ink jet printing head. Further, a support part which braces the oscillation plate is provided between the position of the oscillation plate 7 corresponding to the nozzle and the base.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head used for, for example, a printer, a fax machine, a plotter, a bar code printer, a digital copy machine, and an ink jet printer. The present invention relates to an ink jet print head and an ink jet printer that are attached to a recording medium such as paper to obtain a recording.

[0002]

2. Description of the Related Art Conventional inkjet printers are roughly classified into a continuous type and an on-demand type.
The ink is water-based or oil-based.

In the continuous type, ink is continuously ejected from a nozzle, and ink unnecessary for recording is recovered and reused. The head has high responsiveness, but an ink recovery mechanism is required and the apparatus is complicated. It is expensive.

On the other hand, the on-demand type ejects ink only when necessary, and the response of the head is low, but the device is simple and inexpensive.

The on-demand type includes an electrostatic attraction type that draws ink from a nozzle by electrostatic force, and a pressure pulse type called an impulse jet that pressurizes ink in a pressure chamber and pushes ink from the nozzle.

The pressure pulse type includes a piezoelectric type and a bubble type. The piezoelectric type pressurizes ink by a piezoelectric (electrostrictive) element. The one-chamber type in which ink is supplied through a pressure chamber and the pressure type There is a two-chamber type having two chambers, a chamber and an ink supply chamber.

The one-chamber type includes a Kaiser type having a flat pressure chamber and a soltan type having a cylindrical pressure chamber. In addition, the two-chamber type includes a stem type that directly supplies ink to the vicinity of the nozzle.

FIG. 10 shows the basic principle of the above Kaiser type piezoelectric head unit. On the surface of the substrate 101, an ink supply passage 102, a pressure chamber 103 and a nozzle 104 are provided.
Are continuously formed. Then, the diaphragm 105 is arranged on the surface of the substrate 101, and the outer surface of the diaphragm 105 is
A piezoelectric element 106 is provided so as to face the pressure chamber 103, and a signal generation source 107 is connected so as to apply a voltage between the front and back surfaces of the piezoelectric element 106. An ink container 109 is connected to the ink supply path 102 via a pipe 108.

In the above structure, when a voltage is applied from the signal source 107 to the piezoelectric element 106, the piezoelectric element 106
Causes the vibrating plate 105 to bend, and the ink 1 in the pressure chamber 103
10 is ejected from the nozzle 104 as an ink droplet 110a onto the recording medium 111 for recording.

Then, when the voltage application to the piezoelectric element 106 is released after the ink is ejected, the vibrating plate 105 returns to its original state, and the ejected ink passes through the ink supply path 102 and the pipe 108 by the nozzle capillary force. It is supplied from the ink container 109.

FIG. 11 is a cross-sectional view showing a conventional ink jet print head using the above-mentioned piezoelectric head unit. The piezoelectric head unit is placed on a base 112 and a pressing piece 113 is provided on the inner periphery of one end. A cylindrical pushing frame 114 protruding from the base 112 is engaged with a step 112a on the peripheral edge of the base 112, and a screw 116 passed through a hole 115 of the base 112 is screwed into the pushing frame 114 to fix the pushing frame to the base. And the peripheral edge of the substrate of the piezoelectric head unit is pressed and fixed to the base 112 by the pressing piece 113. In addition, the entire piezoelectric element mounting portion of the piezoelectric head unit is recessed in the base 112.
It is held down by an elastic body 117 provided on 12b.

FIG. 12 is a cross-sectional view showing another conventional ink jet print head using a piezoelectric head unit. A piezoelectric head is provided on a step portion 118a formed on the inner peripheral surface of one end of a cylindrical base 118. The board 101 of the unit is engaged, and the board 101 is directly attached and fixed to the base 118 with a screw 119.

[0013]

[Problems to be Solved by the Invention]
In the conventional inkjet printhead shown in FIG. 3, the portion of the vibrating plate 105 facing the nozzle 104 is not supported, so that a voltage is applied to one or several piezoelectric elements and the vibrating plate 105 corresponding to the piezoelectric element is applied. When the portion is deflected, this deflection causes unnecessary deflection in the portion of the vibrating plate corresponding to the piezoelectric element to which the voltage adjacent to the piezoelectric element is not applied, causing the ink droplet to be ejected. There were inconveniences such as stability, deterioration of printing quality and generation of noise.

Therefore, in order to eliminate this inconvenience, it is possible to increase the pressure applied to the piezoelectric element. However, if the pressure is increased, the ink ejection force is reduced and the energy effect of ejection is reduced. Further, there is a problem that the life of the head is shortened due to resonance of unnecessary vibration of the diaphragm.

The present invention has been made to solve the above-mentioned problems, and is intended to: a. Stabilize ink ejection characteristics and improve printing quality b. Reduce noise c. An object of the present invention is to obtain an inkjet print head and an inkjet printer that can prevent reduction in head life due to vibration of a diaphragm.

[0016]

An ink jet print head according to the present invention supplies a plurality of pressure chambers arranged in two rows, a common ink passage communicating with each pressure chamber, and ink to the common ink passage. And a plurality of nozzles formed linearly penetrating the substrate at adjacent ends of the pressure chambers of the two rows, and attached to the pressure chamber forming surface of the substrate. In the ink jet print head in which a piezoelectric head unit having a vibrating plate and a piezoelectric element attached to the outer surface of the vibrating plate facing the pressure chamber is mounted on a base, the vibrating plate position corresponding to the nozzle is A support portion that supports the diaphragm is provided between the base and the base.

Further, the ink jet printer according to the present invention has the ink jet print head built in a carriage and is reciprocally moved in the row direction of the recording paper.

[0018]

In the ink jet print head according to the present invention, since the position of the vibrating plate corresponding to the nozzle is supported by the supporting portion, the deflection of the vibrating plate due to the deformation of the piezoelectric element to which a voltage is applied is It is possible to prevent the adjacent voltage from being transmitted to the portion of the vibration plate corresponding to the piezoelectric element to which the voltage is not applied, and prevent unnecessary ink ejection from the nozzle.

As a result, it is possible to improve the printing quality and prevent the noise from decreasing and the life from decreasing due to vibration.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a piezoelectric head unit, and FIG. 2 is a plan view of a substrate from which a diaphragm is removed.

In FIGS. 1 and 2, the substrate 1 is made of photosensitive glass, and is made up of a number of pressure chambers 2a to 2n, and the pressure chambers 2a to 2n.
A common ink path 3 communicating with a to 2n, and an ink introduction port 5 for supplying ink 4 from an ink container (not shown) to the common ink path 3 are formed by etching.

One end of each of the pressure chambers 2a to 2n is tapered, and the nozzles 6a to 6n are orthogonal to the pressure chambers 2a to 2n so that the pressure chambers 2a to 2n are aligned in a straight line in the tapered portions which are alternately overlapped in the lateral direction of the paper. It is formed so as to penetrate the substrate 1.

On the surface of the substrate 1 where the pressure chambers 2a to 2n, the common ink passage 3 and the ink introduction port 5 are formed, a diaphragm 7 having a common electrode made of ITO or the like is attached. Then, on the outer surface of the vibrating plate 7, piezoelectric elements 8a to 8n made of PZT or the like are provided to face the pressure chambers 2a to 2n, respectively.
8n are provided separately and independently, and each of the piezoelectric elements 8a-8
n is connected to a signal generation source (not shown) via flexible cables 9a and 9b.

FIG. 3 is a cross-sectional view showing an embodiment 1 of the ink jet print head of the present invention constructed by using the piezoelectric type head unit having the above-mentioned configuration. The substrate 1 of the piezoelectric type head unit is made of metal or rigid. High resin base 1
The stepped portion 10a of 0 is engaged and fixed to the base. Further, the base 10 is provided with a concave portion 11 facing all the mounting portions of the piezoelectric elements 8a to 8n, and a protrusion 12 for supporting the position of the diaphragm 7 corresponding to the nozzles 6a to 6n. Reference numeral 13 is a groove provided to prevent the adhesive material that adheres the substrate 1 to the base 10 from protruding into the ink introduction path 14.

Next, the operation will be described. The distortion of the piezoelectric element to which a voltage is applied deforms the vibrating plate in the portion corresponding to the piezoelectric element, and this deformation changes the volume of the pressure chamber to eject ink from the nozzles 6a to 6n.
In this case, since the positions of the vibrating plate 7 corresponding to the nozzles 6a to 6n are supported by the protrusions 12, the vibrating plate positions of the piezoelectric elements adjacent to the deformed piezoelectric element are not unnecessarily deflected.

After the ink is ejected, the vibrating plate 7 returns to the original state, and the ejected ink is supplied to the ink introduction path 1.
4. The pressure chamber is replenished from the common ink passage 3 through the ink introduction port 5.

Example 2. FIG. 4 is a cross-sectional view of the second embodiment, in which the vibration damping material 15 such as rubber is provided in the concave portion 11 of the first embodiment, so that unnecessary vibration of the diaphragm 7 can be prevented more reliably.

In the embodiment, the damping material 15 has a resonance vibration frequency which is significantly smaller than the resonance frequency of the vibration plate 7, and any one of the vibration plates 7 driven for ink ejection.
On the other hand, when the vibration is transmitted to another diaphragm 7, the vibration can be effectively absorbed, and false resonance of the unselected diaphragm can be surely prevented.

Example 3. FIG. 5 is a transverse cross-sectional view of the third embodiment. In the configuration of the second embodiment, the pressing frame 17 fixed to the base 10 with the screws 16 presses the peripheral edge portion of the substrate 1 of the piezoelectric head unit. The fixing to the base 10 is made stronger.

Example 4. FIG. 6 is a cross-sectional view of the fourth embodiment, in which the elastic member 18 is provided instead of the protrusion 12 in the first embodiment, and unnecessary vibration of the diaphragm 7 can be efficiently reduced. According to the fourth embodiment, unlike the other embodiments, the elastic material 18 needs to be fixed to the base 10 by adhesion or other means, but the position of the diaphragm facing the nozzle is accompanied by some elastic compression. It can be pressed in a state, which enables reliable vibration absorption.

FIGS. 7, 8 and 9 show the overall structure of an ink jet printer according to the present invention, which incorporates the above-mentioned ink jet print head.

In each of the drawings, the ink jet printer includes a flat platen 20 in order to make it small and thin as a facsimile, plotter or bar code printer, and a recording paper not shown is placed on the platen 20 as indicated by an arrow A in FIG. Sent in. In order to properly feed the recording paper, feed rollers 21 and 22 are provided in front of and behind the flat platen 20, respectively, and the recording paper is sandwiched between the idle rollers 23 and 24 facing each other to perform a predetermined amount of feeding action. be able to.

A pair of carriage guides 25 and 26 are provided above the flat platen 20, and a carriage 27 is supported by the carriage guides 25 and 26 so as to be reciprocally movable in the row direction of the recording paper. Although not shown in detail in the carriage 27, a drive system is connected so that the carriage 27 can be moved to an arbitrary position in the row direction with respect to the recording paper by a driving force such as a stepping motor. Therefore, the carriage 27 can reciprocate in the direction indicated by the arrow BC in the figure.

The carriage 27 incorporates the above-mentioned ink jet print head 10 shown in FIGS. 1 to 6, and the above-described one row of nozzles 6 are arranged so as to face the recording paper led onto the platen 20. Has been done.

An ink cartridge 28 is provided below the flat platen 20 in order to supply ink to the ink jet print head 10 built in the carriage 27.
The necessary ink supply from the above to the introduction port 5 of the print head 10 is performed through, for example, a flexible tube.

Further, the ink jet print head 10
In order to prevent the ink from solidifying when the nozzle is not used,
The device is provided with a cleaning unit 29,
When not printing, the carriage 27 moves the print head 10
Are retracted toward the cleaning unit 29.

In order to apply a desired driving force to the paper feeding and cleaning unit 29 described above, the feed motor 3 is used in the ink jet printer as shown in FIG.
0, and a carriage drive motor 31 for driving the above-mentioned carriage 27, each of which is provided with a feed roller 21, through a transmission mechanism (not shown).
22 and the carriage 27 are being driven.

[0038]

As described above, according to the present invention, since the supporting portion for supporting the position of the vibrating plate facing the nozzle is provided, the deflection of the vibrating plate due to the deformation of the piezoelectric element to which a voltage is applied is reduced. It is possible to prevent the voltage from being transmitted to the position of the vibrating plate corresponding to the piezoelectric element to which the voltage is not applied, which is adjacent to the piezoelectric element, and prevent unnecessary ink ejection from the nozzle.

As a result, the ejection direction of the ink droplets and the stability of the ejection speed are improved, the printing quality is improved, the noise is reduced, and the life of the head is improved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a piezoelectric head unit.

FIG. 2 is a plan view showing a substrate which is a constituent element of the piezoelectric head unit shown in FIG.

3 is a cross-sectional view showing a first embodiment of an inkjet head of the present invention in which the piezoelectric head unit of FIG. 1 is assembled on a base.

4 is a cross-sectional view showing a second embodiment of the ink jet print head of the present invention in which the piezoelectric type unit head of FIG. 1 is assembled on a base.

5 is a cross-sectional view showing a third embodiment of the inkjet print head of the present invention in which the piezoelectric type unit head of FIG. 1 is assembled on a base.

6 is a cross-sectional view showing a fourth embodiment of the ink jet print head of the present invention in which the piezoelectric type unit head of FIG. 1 is assembled on a base.

FIG. 7 is a plan view of a main part of an inkjet printer having a print head according to the present invention built therein.

FIG. 8 is a front view of a main part of the inkjet printer shown in FIG.

FIG. 9 is a side view of essential parts of the inkjet printer according to the present invention shown in FIGS.

FIG. 10 is a diagram illustrating the principle of a piezoelectric head unit.

11 is a cross-sectional view of a conventional inkjet printhead in which the piezoelectric head unit of FIG. 10 is assembled on a base.

12 is a cross-sectional view of another conventional inkjet printhead in which the piezoelectric head unit of FIG. 10 is assembled on a base.

[Explanation of symbols]

 1 Substrate 2a to 2n Pressure Chamber 3 Common Ink Chamber 4 Ink 5 Ink Inlet 6a to 6n Nozzle 7 Vibration Plate 8a to 8n Piezoelectric Elements 9a and 9b Flexible Cable 10 Substrate 13 Support Part 15 Damping Material

Claims (4)

[Claims] 1. A substrate having a plurality of pressure chambers arranged side by side in two rows, a common ink passage communicating with each pressure chamber, and an ink introduction port for supplying ink to the common ink passage; A large number of nozzles linearly penetrating the substrate at adjacent ends of the pressure chambers of the row, a vibration plate attached to the pressure chamber forming surface of the substrate, and a vibration plate facing the pressure chambers. An inkjet printhead in which a piezoelectric head unit having a piezoelectric element attached to the outer surface of the base plate is mounted on a base, and a support for supporting the base plate is provided between the base plate and the position of the base plate corresponding to the nozzle. An inkjet printhead characterized in that a section is provided. 2. The ink jet print head according to claim 1, further comprising a damping material interposed between the piezoelectric element and the base. 3. The ink jet print head according to claim 1, wherein the support portion is made of an elastic material. 4. A carriage that is reciprocally movable in a row direction with respect to a platen holding a recording sheet, the carriage is provided with an inkjet print head, and the inkjet print head has a plurality of pressures arranged in two rows. A chamber, a common ink passage communicating with each pressure chamber, an ink inlet for supplying ink to the common ink passage, and a linear shape at the end of each of the two rows of pressure chambers close to each other. A piezoelectric head having a large number of nozzles penetrating the substrate, a vibration plate attached to the pressure chamber forming surface of the substrate, and piezoelectric elements respectively attached to the outer surface of the vibration plate facing the pressure chamber. An ink jet printer in which a unit is attached to a base, and a support portion that supports the vibration plate is provided between the vibration plate position corresponding to the nozzle and the base. .