JPH08290568A - Inkjet print head - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable ink jet print head by preventing oblique adhesion of a pressure generating member in advance. A wall member 1 for partitioning the nozzle openings corresponding to the nozzle openings 102 arranged on a nozzle plate 101.
03 and the vibration plate 104
And a pressure generating member 105 for driving the vibrating plate 104 is arranged, and in an ink jet type print head having an ink flow path 111 for supplying ink to the ink chamber 110, ink is ejected to both ends of the pressure generating member array 105. A feature is that a dummy pressure generating member 701 that does not contribute is provided and the dummy pressure generating member and the diaphragm 104 are electrically connected.

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 to form an image on a recording medium, and more particularly to the structure of an ink jet type print head.

[0002]

2. Description of the Related Art A conventional ink jet print head is
As shown in Japanese Examined Patent Publication No. 60-8953, a plurality of nozzle openings are formed on the wall surface of a container constituting an ink tank, and piezoelectric elements are arranged so that the expansion and contraction directions are aligned so as to face each nozzle opening. It is constructed and set up. This print head applies a drive signal to a piezoelectric element to expand and contract the piezoelectric element, and the dynamic pressure of ink generated at this time causes ink droplets to be ejected from nozzle openings to form dots on printing paper.

In a print head of this type,
It is desirable that droplet formation efficiency and flight force are large. However, since the unit length of the piezoelectric element and the expansion / contraction rate per unit voltage are extremely small, it is necessary to apply a high voltage in order to obtain the flying force required for printing, which complicates the drive circuit and electrical insulation measures. The problem is that

In order to solve such a problem, Japanese Patent Laid-Open No.
As disclosed in Japanese Patent Laid-Open No. 3-295269, there has been proposed a piezoelectric element for an inkjet print head in which electrodes and piezoelectric materials are alternately laminated in a sandwich shape. With this piezoelectric element, the distance between the electrodes can be made as small as possible, so that there is an effect that the voltage of the drive signal can be lowered.

In Japanese Unexamined Patent Publication No. 4-1052, an ink jet in which the above-mentioned laminated piezoelectric element is fixed to a base, the piezoelectric element is processed so as to correspond to the nozzle row pitch, and the piezoelectric element row is fixed to a diaphragm. The printhead is detailed.

[0006]

However, in the above head structure, as shown in FIG. 11, the piezoelectric element and the diaphragm 1 are arranged.
In some cases, foreign matter was interposed between the piezoelectric element array and the piezoelectric element array 04, or the piezoelectric element array was obliquely inserted into the frame 204 as shown in FIG. Further, this defect cannot be found until the ink final inspection of the head final inspection is performed, which leads to a waste of production man-hours.

It is an object of the present invention to provide an inexpensive and highly reliable ink jet print head.

[0008]

An ink jet print head according to the present invention has a plurality of nozzle openings arranged at least in rows for ejecting ink droplets, a pressure chamber communicating with the nozzle openings, and a pressure chamber of the pressure chamber. In an ink jet print head having a pressure generating member connected to a vibrating plate that is one wall surface, the pressure generating members are arranged at regular intervals and contribute to ink droplet ejection at both ends of the pressure generating member row. A dummy pressure generating member is provided, and the dummy pressure generating member and the diaphragm are electrically connected.

[0009]

EXAMPLES Examples of the ink jet print head of the present invention will be described below.

3 and 4 are perspective views of the ink jet type print head according to the present invention.

FIG. 1 is a sectional view of the ink jet print head according to the present invention in a direction orthogonal to the nozzle array, that is, a sectional view taken along the line AA in FIG.

FIG. 2 is a sectional view of the ink jet print head of the present invention in the nozzle array direction, that is, a sectional view taken along the line BB in FIG.

In FIG. 1, FIG. 2, and FIG. 4, ink supplied from an ink tank (not shown) passes through an ink flow path 111 formed in a wall member 103 communicating with each ink chamber 110. Then, the ink is supplied to the ink chamber 110 configured by the nozzle plate 101, the wall member 103, and the vibrating plate 104 through the ink supply passage 107 formed so as to correspond to each ink chamber 110.

A pressure generating member 105 and a nozzle opening 102 are arranged corresponding to each ink chamber 110. The pressure generating member 105 is arranged and fixed on the base plate 201,
It is inserted into the frame 204 and fixed with an adhesive 203. Here, the pressure generating member 105 is the FPC 202,
The ink chamber 110 is pressurized by the expansion and contraction motion by the electric signal from the printer main body via 201, and the nozzle opening 1
Ink is ejected from 02.

Next, a method of manufacturing the ink jet print head of the present invention will be described.

In FIG. 5, a piezoelectric element unit 501 is manufactured in which the FPC 202 is mounted on the pressure generating member 105 which is fixed to the base plate 201 and processed so as to correspond to the nozzle pitch.

On the other hand, as shown in FIGS. 2, 9, 10, and 11, the vibrating plate 104 has an island-shaped protrusion 209 at a position corresponding to the ink chamber 110 and the other vibrating film 210 which is easily deformed. Have. Island-shaped protrusion 209 of diaphragm 104
Is an adhesive 112 applied to the end surface of the pressure generating member 105.
Is fixed by means of the above, and there is an effect of efficiently changing the volume of the ink chamber 110 due to the displacement of the pressure generating member 105.

The vibrating plate 104 having such a structure has a thin resin layer (for example, PI, PPS or P) which becomes the vibrating film portion 210 on a metal plate (for example, SUS or Ni, t = 10 to 50 μm).
E, etc., t = 1 to 10 μm) to form island-shaped protrusions 209.
It can be formed by selectively etching the metal part while leaving.

A nozzle unit 601 in which the vibrating plate 104, the wall member 103 and the nozzle plate 101 are laminated and adhered
Is prepared. After this, as shown in FIG.
4, the nozzle unit 601 is bonded to the pressure generating member 105, and at the same time, the piezoelectric element unit 501 having the adhesive 112 applied on the upper surface of the pressure generating member 105 is inserted, and the island-shaped protrusion 209 and the pressure generating member
05 Join with the upper surface.

Here, if the piezoelectric element unit 501 can be inserted into the frame 204 as shown in FIG. 7, all the piezoelectric element rows are evenly arranged as shown in FIG. 10 which is an enlarged view of FIG.
It will be able to adhere to 09.

However, as shown in FIG. 8, the piezoelectric element unit 501 is caught on the wall of the frame 204 for some reason, or as shown in FIG. 11 which is an enlarged view of FIG. If a foreign substance falls in between 209, the pressure generating member 10 as shown in FIG.
5 A gap is created between the upper surface and the island-shaped protrusion 209.

This results in a defective joint between the pressure generating member 105 and the vibrating plate 104, the displacement of the pressure generating member 105 is not transmitted to the vibrating plate 104, and the ink chamber 110 cannot be sufficiently pressurized. This will lead to uneven discharge.

Conventionally, this defect could not be found until the final inspection, that is, the ink discharge check, leading to a waste of production man-hours and accessory parts.

The feature of the present invention is to detect and correct this defect in advance.

The pressure generating member 105 of the present invention is shown in FIGS. 7, 8, 10 and 11, and the top view of the diaphragm 104 of the present invention is shown in FIG.

In FIGS. 7, 8, 10, and 11, both ends of the pressure generating member 105 are dummy pressure generating members 701 that do not contribute to ink ejection.
Reference numeral 01 is a structure for electrically contacting the dummy pressure generating member contact portion 901 indicated by the wavy line on the diaphragm 104 in FIG. Further, the dummy pressure generating member contact portion 901 is electrically connected to the probe contact portion 902.

7 and 10 show the piezoelectric element unit 501.
Is inserted into the diaphragm 104 in a good condition.

In this case, as shown in FIG. 6, electrical contact can be detected by the probe contact portions 702 provided on both ends of the FPC 202 which are electrically connected to the dummy pressure generating member 701 and the probe contact portions 902 formed on the diaphragm 104. Becomes

On the other hand, FIGS. 8 and 11 show the state in which the piezoelectric element unit 501 is inclined with respect to the diaphragm 104, or the foreign matter 1101 is inserted.

In this case, as shown in FIG. 6, both ends of the FPC 202 electrically connected to the dummy pressure generating member 701 and the diaphragm 1 are connected.
The electrical continuity cannot be detected at the probe contact portion 902 formed at 04 on both sides or one side of the probe contact portion 702 of the FPC 202.

In this case, the piezoelectric element unit 501 once inserted is pulled out, inspected, corrected, and then inserted again.

Therefore, according to the present invention, the pressure generating member 105
It has become possible to detect in advance an adhesion defect between the diaphragm 104 and the diaphragm 104, and remove or correct the defect.

At this time, according to the present invention, the thickness of the adhesive 112 applied between the pressure generating member 105 and the island-shaped projections 209 is controlled to be several μm. Even if 112 is interposed, the minute unevenness on the upper surface of the pressure generating member 105 and the dummy pressure generating member contact portion 9 of the vibration plate 104.
It is possible for the minute irregularities on the surface 01 to make electrical contact. On the contrary, when the thickness of the adhesive 112 is thicker than the desired value, electrical contact becomes impossible, so that the thickness of the adhesive can be controlled in the present invention, and a head having stable ejection characteristics is provided. done.

When the thickness control of the adhesive 112 is easy, a conductive adhesive is applied to the adhesive 112 in order to ensure the electrical continuity between the dummy pressure generating member 701 and the dummy pressure generating member contact portion 901. It is also possible to use or to contain conductive particles in the adhesive 112.

The head specifications of this embodiment shown in FIG. 5 are shown below.

<Head specifications> Nozzle array pitch: 0.1411 (mm) (180 dpi) Number of nozzles per row: 32 (nozzles) Number of nozzle rows: 5 (rows) In response to printer demands for higher printing speed in the future There are two methods of increasing the driving cycle of the pressure generating member and increasing the number of nozzles, but the former method of increasing the driving cycle is to discharge. There is a limit because the amount of ink is limited.

On the other hand, the latter method of increasing the number of nozzles is the easiest method to meet the demand for higher printing speed without the limitation of the former method.

In order to increase the number of nozzles, it is possible to increase the number of nozzles per one row or increase the number of nozzle rows. The problem at this time is a decrease in the yield due to oblique adhesion of the piezoelectric element unit as in the embodiment of the present invention, but the method of detecting the quality of the adhesion at both ends of the piezoelectric element unit as in the present invention increases the number of nozzles. Has effect regardless.

In this embodiment, an example in which a laminated piezoelectric element in the d31 direction utilizing displacement in the direction perpendicular to the electric field direction is used as the pressure generating member has been shown, but the present invention is not limited to this. The same effect can be obtained by a piezoelectric element that uses displacement in the d33 direction that utilizes displacement in the same direction as the electric field direction, or a pressure generating member that generates mechanical ink ejection generating force by a drive signal.

[0040]

As described above, the ink chamber constituted by the wall member partitioning the nozzle openings and the vibrating plate corresponding to the nozzle openings arranged on the nozzle plate,
In an ink jet print head having a pressure generating member for driving the vibrating plate and having an ink flow path for supplying ink to the ink chamber, both ends of the pressure generating member row do not contribute to ink ejection. The dummy pressure generating member is electrically connected to the diaphragm.

Further, the adhesive interposed between the pressure generating member and the vibration plate is a conductive material. Further, the adhesive agent interposed between the pressure generating member and the vibrating plate contains conductive particles.

As a result, the oblique adhesion of the pressure generating member was found in advance, and an inexpensive and highly reliable ink jet print head could be provided.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the line AA in FIG. 3 showing an embodiment of an ink jet print head of the present invention.

FIG. 2 is a sectional view taken along line BB in FIG. 3 showing an embodiment of the ink jet print head of the present invention.

FIG. 3 is a perspective view showing an embodiment of the inkjet print head of the present invention.

FIG. 4 is a perspective view showing an embodiment of the ink jet print head of the present invention.

FIG. 5 is a perspective view showing an embodiment of the ink jet print head of the present invention.

FIG. 6 is a perspective view showing an assembly process of the inkjet print head of the present invention.

FIG. 7 is a diagram showing a good assembled state of the ink jet print head of the present invention.

FIG. 8 is a diagram showing an example of a defectively assembled state of the inkjet print head of the present invention.

FIG. 9 is a top view showing the structure of the vibration plate of the inkjet print head of the present invention.

FIG. 10 is a detailed view of part A in FIG. 7 showing a good assembled state of the ink jet print head of the present invention.

FIG. 11 is a detailed view of a part in FIG. 8 showing an example of a defective assembly state of the ink jet print head of the present invention.

[Explanation of symbols]

 101: Nozzle plate 102: Nozzle opening 103: Wall member 104: Vibration plate 105: Pressure generating member 209: Island-shaped projection 210: Vibration film part 701: Dummy pressure generating member 702: Probe contact part 902: Probe contact part

Claims (3)

[Claims] 1. A pressure generating member connected to at least a plurality of nozzle openings arranged in a row for ejecting ink droplets, a pressure chamber communicating with the nozzle openings, and a vibrating plate which is one wall surface of the pressure chamber. And a dummy pressure generating member that does not contribute to ink droplet ejection is provided at both ends of the pressure generating member array, wherein the pressure generating members are arranged at regular intervals. An ink jet type print head, characterized in that the diaphragm and the diaphragm are electrically connected. 2. The ink jet print head according to claim 1, wherein the adhesive interposed between the pressure generating member and the vibration plate is a conductive material. 3. The ink jet print head according to claim 1, wherein the adhesive interposed between the pressure generating member and the vibration plate contains conductive particles.