JP3291999B2 - Ink jet print head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to the structure of a print head used in an ink jet printer.

[0002]

2. Description of the Related Art A conventional ink jet print head is:
As shown in Japanese Patent Publication No. 60-8953, Japanese Patent Publication No. 60-8953, a plurality of nozzle openings are formed on the wall of a container constituting an ink tank, and the directions of expansion and contraction are matched so as to face each nozzle opening. It is configured by disposing a piezoelectric element. In this print head, a drive signal is applied to a piezoelectric element to expand and contract the piezoelectric element, and ink droplets are ejected from nozzle openings by dynamic pressure of ink generated at this time to form dots on printing paper.

[0003] In a print head of this type,
It is desirable that the droplet formation efficiency and the flying force be large. However, since the piezoelectric element has a very small unit length and expansion / contraction ratio per unit voltage, it is necessary to apply a high voltage to obtain the flying force required for printing, which complicates the drive circuit and measures for electrical insulation. There is a problem of becoming.

In order to solve such a problem, as disclosed in Japanese Patent Application Laid-Open No. 63-295269, an electrode and a piezoelectric material are alternately laminated in a sandwich form for an ink jet print head. Piezoelectric elements have been proposed. According to this piezoelectric element, the distance between the electrodes can be reduced as much as possible, so that the voltage of the drive signal can be reduced. Japanese Patent Application Laid-Open No. 4-1052 discloses an ink jet print head in which the above-mentioned laminated piezoelectric element is fixed to a base, then the piezoelectric element is processed so as to correspond to the nozzle row pitch, and this piezoelectric element row is fixed to a diaphragm. Is described in detail.

[0005] In recent years, along with the use of color PCs and the rise of recycled paper due to environmental protection, printers have also been required to have high print quality on poor paper quality.

In order to respond to this demand, ink jet printers have taken measures such as developing ink with less bleeding and installing a heater near the platen to increase the drying speed of the ink. However, this
As a result, the degree of freedom in selecting component parts and manufacturing conditions is limited, such as ensuring the ink resistance of the components of the ink jet print head and avoiding the occurrence of thermal stress due to differences in linear expansion coefficients. . JP-A-7-164634 and JP-A-7-164636 disclose a structure in which a stress caused by a difference in a coefficient of linear expansion between components due to heat is relaxed.

[0007]

However, with the above-described head structure, it is impossible to avoid the occurrence of stress at the portion C as shown in FIG. In addition, the deterioration of reliability due to the generation of stress in the portion C has become a problem that becomes apparent as the head becomes larger with the increase in the number of nozzles.

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

[0009]

According to the present invention, there is provided an ink jet print head comprising: a nozzle plate having nozzles;
An ink chamber communicating with the nozzle, and supplying ink to the ink chamber.
The ink flow path to be supplied, and the ink path connecting the ink chamber and the ink flow path.
And a wall member having an ink supply path formed thereon and laminated on the wall member.
And a diaphragm constituting the wall surface of the pressure chamber thus formed.
Ink chamber member and the nozzle in contact with the diaphragm.
Pressure is generated in the ink chamber to eject ink drops.
Pressure generating member, the ink chamber constituting member and the pressure
Ink cartridge having frame member supporting force generating member
In a jet-type print head, a plate-shaped buffer member is disposed between the ink chamber constituting member and the frame member. Further, the pressure generating member is inserted into the buffer member.
There is a hole in the entrance. Further, the present invention is characterized in that the buffer member has an escape groove for compliance of the diaphragm.

Also, the coefficient of linear expansion (CT
E), CTE of the wall member <CTE of the buffer member <
The CTE of the frame member is characterized.

[0011] Further, the invention is characterized in that the buffer member is a metal, a stainless steel material among metals, or a resin.

Further, a thin portion is formed on the diaphragm, and a groove is formed at a position corresponding to the thin portion of the cushioning member.

[0013]

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

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

In FIGS. 1, 2 and 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. The ink is supplied to the ink chamber 110 formed by laminating the nozzle plate 101, the wall member 103, and the vibration plate 104 through an ink supply path 107 formed so as to correspond to each ink chamber 110. Here, the nozzle plate 101, the wall member 103, and the vibration plate 104 of the ink chamber constituent members are fixed to the buffer member 220 and the frame 204.

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

The method of manufacturing the head will be described below.

In FIG. 1, a piezoelectric element unit 501 is manufactured in which an FPC 202 is mounted on a pressure generating member 105 which is fixed to a base plate 201 and processed so as to correspond to a nozzle pitch.

On the other hand, the ink chamber constituting member 60 in which the vibration plate 104, the wall member 103, and the nozzle plate 101 are laminated and bonded.
Prepare No. 1. Here, as shown in FIG.
4 is an island-like projection 20 at a position corresponding to the ink chamber 110.
9 and other vibrating membrane portions 210 that are easily deformed. The island-shaped protrusion 209 of the vibration plate 104 is fixed by an adhesive 112 applied to an end face of the pressure generating member 105, and the ink chamber 110 is displaced by the pressure generating member 105.
Has the effect of efficiently changing the volume. The diaphragm 104 having such a configuration is formed on a metal plate (for example, t
= 10 to 50 µm), a thin resin layer (for example, PI, PPS, PE, etc., t = 1 to 10 µm) to be the vibrating film portion 210 is formed, and the metal portion is selectively etched while leaving the island-shaped protrusions 209. Can be formed by things.

The wall member 103 has an ink ejection speed,
It is an important part that determines the discharge amount and the like. To meet the demand for high image quality accompanying color printing, dimensional accuracy of several microns is required.

In this embodiment, in order to meet this requirement, a silicon single crystal substrate having a crystal orientation (110) plane on its surface was manufactured by anisotropic etching.

In the anisotropic etching method for a silicon single crystal substrate, etching proceeds in a direction determined by the crystal orientation. Since the (111) crystal plane has an extremely low etching rate as compared with the other crystal planes, if the ink chamber portion requiring dimensional accuracy is constituted by the (111) plane, the ink chamber having a very high aspect ratio is formed. Can be formed with high density and high precision. This is also known in U.S. Pat. No. 4,311,2008.

The nozzle plate 101 was manufactured by forming a hole in a SUS material at a desired pitch by a press method.

The frame 204 is provided with the piezoelectric element unit 5.
In order to provide a function of aligning the island-shaped projections 209 with the island-shaped projections 209, high accuracy such as dimensional accuracy and flatness is required. In this embodiment, at relatively low cost, post-processing for obtaining flatness,
That is, injection molding of a liquid crystal polymer is employed as a material that can be easily wrapped.

Conventionally, thereafter, the vibration plate 104, the wall member 103, and the nozzle plate 101 are laminated and adhered to produce the ink chamber constituting member 601. Then, the ink chamber constituting member 601 is adhered to the frame 204 and the pressure generating member is simultaneously formed. The piezoelectric element unit 501 with the adhesive 112 applied on the upper surface of the pressure generating member 105 is inserted to position and join the island-shaped protrusion 209 and the upper surface of the pressure generating member 105.

However, with the conventional structure, in order to meet the demands for high-speed printing on poor paper quality and high printing quality, the use of multiple nozzles in the head, the development of ink with less bleeding, and the installation of a heater near the platen to dry the ink Due to measures such as increasing the speed, issues such as deterioration of the ink resistance of the components of the ink jet print head and deterioration of the reliability due to the occurrence of thermal stress due to the difference in linear expansion coefficient are apparent. It has become.

In particular, the generation of thermal stress due to the difference in the coefficient of linear expansion has become apparent due to an increase in the environmental temperature exposed during the head manufacturing process, such as adhesion hardening, and an increase in the environment in which the head is used.

JP-A-7-164634, JP-A-7-1
No. 64636 discloses a structure that relieves stress caused by a difference in linear expansion coefficient between components due to heat.

However, in the above head structure, FIG.
As shown in (1), it is impossible to avoid the occurrence of stress in the portion C.

Further, the deterioration of reliability due to the generation of stress in the portion C has become a problem that becomes apparent as the size of the head increases as the number of nozzles increases.

In contrast to the structure shown in FIG. 7, the head according to the present invention comprises an ink chamber forming member 601 and a frame 20 as shown in FIG.
4, a buffer member 220 for buffering a stress generated due to a difference in linear expansion coefficient is provided.

According to this structure, the ink chamber constituting member 60
7 is received by the buffer member 220 on the frame 204, so that stress generation as in the portion C in FIG. 7 is small.

Here, the material of the cushioning member 220 governs the linear expansion coefficient (hereinafter referred to as CTE) of the cushioning member 220 and the stress generated in the ink chamber constituting member 601 formed by the nozzle plate 101, the wall member 103, and the vibration plate 104. That is, the CTE of the wall member 103, which is a component having a large rigidity and the largest difference from the CTE of the frame 204, and the frame 204
CTE of the wall member 103 <cushion member 2
SUS430 was adopted as a material having a relationship of 20 CTE <CTE of the frame 204.

Incidentally, the CTE of SUS430 is 9E-
6 / ° C. Table 1 shows the material, CTE, Young's modulus, and plate thickness of the head components used in this example.

In this case, the temperature of the frame 204 caused by the temperature rise is increased.
Since the expansion of the ink chamber can be restricted by the buffer member 220, the stress generated at the interface between the ink chamber constituting member 601 and the frame 204 can be reduced.

Due to this, the temperature rise in the head manufacturing process,
A highly reliable head can be provided with respect to changes in the operating environment temperature.

Here, as shown in FIG. 1, the buffer member 220 has a hole 130 in the pressure generating member insertion portion and a diaphragm 104.
It is necessary to provide an escape groove 131 for compliance.

The method for manufacturing the cushioning member 220 is as follows.
Pressing is desirable, but when the thickness of the cushioning member increases, processing deformation and burr generation due to pressing become problems. At this time, a plurality of SUs processed into a desired shape
The same effect can be obtained even when the S plate is laminated and adhered by a method such as an adhesive or diffusion bonding and used as the cushioning material 220.

As another material of the cushioning member 220, a thermosetting resin may be used. The desired shape can be easily obtained by injection molding for thermosetting resin.
Is effective because there are many small materials.

[0041]

[Table 1]

Thereafter, as shown in FIG.
The ink chamber constituting member 6 is attached to the frame 204 and the buffer member 220.
At the same time as bonding, the piezoelectric element unit having the adhesive 112 applied to the upper surface of the pressure generating member 105 is inserted, and the island-shaped protrusion 209 and the upper surface of the pressure generating member 105 are positioned and joined to obtain an ink jet print head. .

FIG. 5 is a perspective view of the head of this embodiment. The head specifications are as follows.

[0044]

[Table 2]

The head structure of the present invention not only relieves the stress generated due to the difference in the coefficient of linear expansion in the horizontal direction, but also reduces the deformation of the pressure generating member 105 and the frame 204 in the vertical direction, that is, in the ink ejection direction, due to heat. The difference can be reduced.

This means that the upper surface of the pressure generating member 105 and the frame 20 are balanced at the adhesive curing temperature at the time of manufacturing the head.
4 Pressure generating member 10 generated when upper surface returns to normal temperature
5 has an effect of suppressing the protrusion of the ink No. 5 toward the ink chamber, thereby reducing the variation in ink ejection.

In this embodiment, an example is shown in which a laminated piezoelectric element in the d31 direction using displacement in the direction perpendicular to the electric field direction is used as the pressure generating member. However, the present invention is not limited to this. As shown in FIG. 6, the same effect can be obtained even with a piezoelectric element utilizing displacement in the d33 direction utilizing displacement in the same direction as the direction of the electric field.

[0048]

As described above, according to the ink jet print head of the present invention, the difference in the coefficient of linear expansion between the ink chamber constituting member and the frame 220 is buffered, and a highly reliable ink jet print head is provided. it can.

Further, the upper surface of the pressure generating member and the upper surface of the frame, which are balanced by the adhesive curing temperature at the time of manufacturing the head, have the effect of preventing the pressure generating member from projecting toward the ink chamber when the temperature returns to normal temperature. In addition, variations in ink ejection can be reduced.

[Brief description of the drawings]

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

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

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

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

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

FIG. 6 is a sectional view showing an embodiment of the ink jet print head of the present invention.

FIG. 7 is a sectional view showing a conventional ink jet print head.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Nozzle plate 102 Nozzle opening 103 Wall member 104 Vibration plate 105 Pressure generating member 131 Compliance escape groove 209 Island-like projection 210 Vibrating film part 220 Buffer member

Claims (7)

(57) [Claims] A nozzle plate having a nozzle;
Ink chamber communicating with the nozzle, supplying ink to the ink chamber
Ink flow path, an ink path that connects the ink chamber and the ink flow path.
A wall member on which a supply channel is formed, and a wall member laminated on the wall member.
And a diaphragm constituting a wall surface of the pressure chamber.
A chamber member and an ink droplet ejected from the nozzle in contact with the diaphragm
Pressure generating member for generating pressure in the ink chamber
And supporting the ink chamber constituent member and the pressure generating member.
Ink jet print head with frame member
Oite, plate between the frame member and the ink chamber structure member
An ink jet print head , wherein the buffer member is disposed. 2. A hole in a pressure generating member insertion portion of the buffer member.
2. The ink jet according to claim 1, wherein:
Type print head. 3. The ink jet print head according to claim 1, wherein said buffer member has an escape groove for compliance of the diaphragm. 4. A linear expansion coefficient of the buffer member (CTE)
2. The relationship of CTE of the wall member <CTE of the buffer member <CTE of the frame member is satisfied.
The ink-jet print head according to claim 1. 5. The ink jet print head according to claim 1, wherein a said cushioning member is a metal. 6. ink jet print head according to claim 1, wherein a said cushioning member is a stainless steel material. 7. The ink jet print head according to claim 1, wherein a said cushioning member is a resin. 8. to form a thin portion on the diaphragm,
6. The ink jet print head according to claim 1, wherein a groove is formed at a position corresponding to the thin portion of the buffer member. ".