JPH02238950A - Ink jet recorder - Google Patents

Abstract

PURPOSE:To obtain a head which can be driven easily by selectively driving one section of piezoelectric vibrator corresponding to an ink flow path and displacing the opposite side walls of the ink flow path thereby improving the head characteristic. CONSTITUTION:Upon application of voltage onto a drive electrode 7-4, a piezoelectric vibrator 2-4 is distorted and elongated in the direction of the thickness. Since the joint between the barrier walls 5-3, 5-4 of flow path is displaced, flexure deformation is provided as a whole. Consequently, the volume of an ink flow path 4-4 is increased. Upon interruption of voltage application onto the piezoelectric vibrator 2-4, distortion energy functions in resetting direction. Consequently, the volume of the ink flow path 4-4 decreases abruptly to cause pressure increases thus delivering ink drops through a delivery port 12 corresponding to the ink flow path 4-4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet recording apparatus, and more particularly to a head mechanism of an inkjet recording apparatus. The prior art related to the present invention is disclosed in Japanese Patent Publication No. 601-8953.
Publication No., JP-A-63-252750, JP-A-61
-45542, JP-A-59-159358, etc. Conventional on-demand inkjet heads using piezoelectric actuators have the disadvantage that it is difficult to achieve high integration of the actuators, and increasing the integration requires higher drive voltages. The above conventional technology improves these problems. In Japanese Patent Publication No. 80-8953, a piezoelectric actuator is provided in the ink opposite to the nozzle, and the ink is ejected by driving the piezoelectric actuator. However, there are limits to high integration due to the characteristics of piezoelectric vibrators. Japanese Patent Publication No. 61-45542 uses a beam-shaped piezoelectric actuator as the partition wall of the flow path, and by using the beam-shaped actuator as the flow path partition wall, it solves the problem of reduction in actuator area due to high integration. ,
There are manufacturing difficulties in processing and arranging piezoelectric elements, and there is a need to reduce processing costs. Furthermore, in Japanese Patent Application Laid-open No. 63-252750, ink is ejected by driving the partition wall of a flow path with a piezoelectric actuator, and similarly to the above-mentioned Japanese Patent Publication No. 61-45542, the partition wall of the flow path is used as an actuator. This solved the problem of reducing the actuator area due to high integration, and also improved efficiency by adding a piezoelectric element and operating in mode. However, manufacturing difficulties such as processing piezoelectric elements and forming electrodes cannot be resolved, and there is a need to reduce processing costs. In addition, since a voltage is applied to the drive electrode and the ground electrode in a complicated manner, it is complicated to take out and connect the electrodes. Japanese Patent Application Laid-Open No. 59-159358 discloses a structure in which a piezoelectric actuator (block-shaped) is attached to the wall of a flow channel. However, since there is a buffer section to prevent mutual interference, the degree of integration is poor. ■-15 The present invention was made in view of the above-mentioned circumstances.
Using piezoelectric vibrators with low power consumption, it is possible to easily manufacture highly integrated heads, improve the efficiency of head characteristics,
This was developed with the aim of providing a head for an inkjet recording device that can be executed using N simple driving methods. In order to achieve the above object, the present invention provides an ink flow path that communicates with an ejection port, a flow path partition that separates the ink flow path, and an ink supply unit that communicates with the ink flow path. and has
By providing a piezoelectric vibrator for generating deformation at the joint portion of the flow path partition wall and driving the piezoelectric vibrator,
In the inkjet head, the root portion of the flow path partition wall is deformed, the flow path partition wall is displaced, and a pressure change is generated in the ink flow path to eject an ink droplet from the ejection port. By selectively driving one portion of the piezoelectric vibrator corresponding to the ink flow path, displacement is caused in both side walls of the flow path forming the corresponding ink flow path; The piezoelectric vibrator is substantially cut for each ink flow path, furthermore, the piezoelectric vibrator is driven in the direction of thickness vibration, and furthermore, the flow path partition wall is formed of Si. The present invention is characterized in that a bottom wall portion having an etching rate smaller than that of Si is provided on the joint surface between the flow path partition wall and the piezoelectric vibrator. The present invention will be explained below based on examples. FIG. 1 is a configuration diagram for explaining one embodiment of an inkjet recording apparatus according to the present invention, in which 1 is a discharge port plate;
2 is a piezoelectric vibrator, 3 is a substrate, 4 is an ink channel, 5 is a channel partition, 6 is an upper substrate, 9 is a slit, 1l is a bottom wall portion, 12
is the outlet. The piezoelectric vibrator 2 is bonded onto a substrate 3, and a slit 9 is provided to substantially separate the flat plate. A channel partition wall portion is arranged on the upper surface of the piezoelectric vibrator 2, and a bottom wall portion 11 is joined to the piezoelectric vibrator 2. A channel partition wall 5 is arranged above the bottom wall portion 11 so as to correspond to the slit 9. An upper substrate 6 is bonded to the upper surface of the channel partition wall 5, whereby each ink channel 4 is separated and formed. An ejection port plate 1 having ejection ports 12 corresponding to the ink flow path 4 is joined to one end of the ink flow path 4 . The other end of the ink flow path 4 is connected to a common liquid chamber, and an ink supply section (
(not shown). FIG. 2 is a sectional view taken along the line AA in FIG. 1, for explaining the operation of the head section of the present invention. When a voltage is applied to the drive electrode 7-4, the piezoelectric vibrator 2-4 is distorted and elongated in the thickness direction (d33 direction strain) (the piezoelectric vibrator 2-4 is polarized in the thickness direction). As a result, the flow path distance 15
-3.5-4 has a displacement applied to its joint, so the entire body undergoes flexural deformation (dotted chain line). This increases the volume of the ink flow path 4-4. By stopping the voltage application to the piezoelectric vibrator 2-4 in this state, the strain energy works in the direction of returning to the original state, so the volume in the ink flow path 4-4 rapidly decreases, and the ink increases due to the pressure increase. From the discharge port 12 corresponding to the flow path 4-4,
Ink droplets are ejected. At this time, start-up of voltage application takes a relatively long time, and start-up takes a short time. Conversely, the application of voltage causes the piezoelectric vibrator 2-4 to shrink in the thickness direction, thereby causing the entire flow path partition wall 5-3, 5-4 to bend inward with respect to the ink flow path 4-4. By deforming it, it is also possible to eject ink droplets by changing the pressure when voltage is applied. At this time, start-up of voltage application is done in a relatively short time, and start-up is done in a long time. The expansion and contraction of the piezoelectric vibrator 2 can be set by appropriately selecting the polarization direction and the electric field direction. In addition, in the figure, 8 is a common electrode. Next, the head processing method will be explained based on Fig. 3. A piezoelectric vibrator 2 (thickness 0.1 to 0.5
am) are joined by adhesive etc. Groove processing is performed on the piezoelectric vibrator 2 by appropriately using machining such as cutting, various etching processes, beam processing such as laser, electric discharge machining, ultrasonic processing, etc. alone or in combination,
Form slit 9. Here, the slit 9 only needs to substantially separate the piezoelectric vibrator 2. In addition, the fourth
It is not necessary to completely separate the piezoelectric vibrator 2 as shown in the figure.
Alternatively, the slits 9 may be made up to the substrate 3 as shown in FIG. At this time, since the piezoelectric vibrator 2 has electrodes formed on both surfaces in advance in the thickness direction, by this groove processing, the upper surface becomes a separate and independent driving electrode, and the lower surface becomes a common electrode.
In the case of FIG. 5, a common electrode can be achieved by making the substrate 3 a conductive material such as metal or Si (FIG. 3 1a). Next, the members for forming the flow junction partition are attached to the piezoelectric vibrator 2.
Join to. The channel partition wall 5 can be formed in the same way as the groove machining of the piezoelectric vibrator 2, but it can be easily formed by using, for example, Si anisotropic etching technology. In this case, the bottom wall portion 11, which has a lower etching rate than Si such as an oxide film layer, nitride film layer, or metal film layer, is usually 0.05 μm to 50 μm thick.
Preferably from 0.05pm to 10pm. Optimally O. l
It is formed to a thickness of μm to 5 μm. As a result, due to the difference in etching rate, groove processing is performed leaving the bottom wall portion 11, thereby forming the channel partition wall 5 and the ink channel 4.
At this time, the bottom wall 11 acts as a protective layer for the piezoelectric vibrator 2 (if the bottom wall 11 is a conductor, an insulating layer is required for the drive electrode of the piezoelectric vibrator 2). On the other hand, the bottom wall portion 11
prevents efficient transmission of the displacement of the piezoelectric vibrator 2, so the above thickness is desired (Fig. 3-b, c)
), In the figure, 10 is a partition member and 13 is a bottom wall layer. In addition, the flow path partition wall 5 and the ink flow path 4 can also be formed by resin molding, dry film, etc. However, according to the above-mentioned Si anisotropic etching technique, the bottom wall 1
This is very suitable because it allows easy processing control of 1 on the μm order. Next, when the upper substrate 6 is bonded to the channel partition 5, the channel partition 5 is formed into a beam shape with both ends fixed, and the ink channel 4 is also completely separated. At this time, the flow path distance l! The upper substrate 6 may be arranged such that the tip of the upper substrate 5 is a free end without being bonded to the upper substrate 6, and the channel partition wall 5 has a cantilever shape. In this case, so that the gap between the channel partition wall 5 and the upper substrate 6 has sufficient fluid resistance,
Usually 1μm to 50μm, preferably 1μm to 30μm
It is preferable that the ink flow paths 4 are arranged as a gap of m, so that the ink flow paths 4 are substantially independently separated. Furthermore, when bonding the upper substrate 6 to the channel partition wall 5, it is also good to provide an elastic layer of a suitable rubber, resin, or the like. This elastic layer acts in the direction of weakening the restraining force of the flow path partition wall 5 due to its connection with the upper substrate 6, and makes the partition wall intermediate between the above-mentioned both-end fixed beam shape and cantilever beam shape, and
The ink flow path 4 is completely separated. At this time, the adhesive layer may also serve as the elastic layer. 4 to 7 show other embodiments of the head portion of the present invention. Although the method of joining the upper substrate 6 after processing the flow path partition wall portion has been described above, a method of processing the upper substrate 6 and the flow path partition wall portion as one body may also be used. At this time, for example, the flow junction partition wall 5 may be directly joined to the piezoelectric vibrator 2 (
Figure 4). In this case, a protective layer on the electrode surface of the piezoelectric vibrator 2,
An insulating layer, etc. is required. Figure 5 shows the case where the slit 9 is made up to the part of the substrate 3. Regarding the groove machining of the piezoelectric vibrator 2, see Fig. 6 for Fig. 4.
You can also do this from the board 3 side as shown in the figure. As mentioned above, it is desirable that the piezoelectric vibrator is substantially cut for each ink flow path, but in order to further simplify processing, it is possible to pattern the drive electrode independently for each ink flow path. It is also possible to form the piezoelectric vibrator without grooving it (FIG. 7). However, in this case, the characteristics will be worse. Furthermore, the piezoelectric vibrator 2 can be of a laminated type, which allows for low voltage driving. In the above embodiment, the piezoelectric vibrator was placed only on one side of the flow path partition wall, but by providing it on both sides, the flow path partition li5
It is also possible to make the bending easier. The piezoelectric vibrator 2 and the flow path partition wall 5 are displaced and the ink flow JI
There is something that causes a pressure change in the discharge port plate 1.
It is inconvenient that a similar displacement occurs at the joint surface with the discharge port plate 1, the channel partition wall 5, or the joint surface, as it will cause harmful stress. Therefore, in order to alleviate or absorb this stress, it is possible to provide a suitable adhesive layer at the joint or install a buffer material. Further, the arrangement of the discharge port plate 1 is not limited, and may be placed on the upper surface of the upper substrate 6.

The embodiments described above can be installed in various combinations. As is clear from the above explanation, according to the present invention. *The connection of the dynamic electrode and common electrode (earth electrode) has been simplified, making processing easier and simplifying the voltage application during driving. In addition, by substantially separating each piezoelectric vibrator, vibration interference between piezoelectric vibrators is eliminated, and displacement can be applied efficiently to the flow channel partition wall, making it possible to reduce driving voltage. , mutual interference decreased. Additionally, since the drive electrodes are formed by grooving the piezoelectric element, there is no need for a special electrode formation process. moreover,
The discharge efficiency has been improved, and the process of forming the flow path partition wall has become easier. Furthermore, since the bottom wall part can be easily machined with high precision, the displacement characteristics are good, and there is an advantage that there is no need to provide a protective layer, an insulating layer, etc. on the electrode surface.

[Brief explanation of drawings]

FIG. 1 is a block diagram for explaining an embodiment of an inkjet recording apparatus according to the present invention, and FIG. 2 is a diagram for explaining the operation of the head section of the present invention. The cross-sectional view and FIG. 3 are diagrams for explaining the head processing method.
4 to 7 are diagrams showing other embodiments of the head portion of the present invention. 1... Discharge port plate, 2... Piezoelectric vibrator,
3... Substrate, 4... Ink channel, 5... Channel partition, 6... Upper substrate, 7... Drive electrode, 8... Common electrode, 9... Slit, 10 ...Partition wall member, 11...
・Bottom wall part, 12...Discharge port, 13...Bottom wall layer part. Figure J Figure (b) (C) Figure

Claims (1)

[Claims] 1. It has an ink flow path that communicates with the ejection port, a flow path partition that separates the ink flow path, and an ink supply section that communicates with the ink flow path, and transforms into a joint of the flow path partition. A piezoelectric vibrator for generating is provided, and by driving the piezoelectric vibrator, deformation is generated at the root portion of the flow path partition, causing displacement in the flow path partition, and causing a pressure change in the ink flow path. In an inkjet head that generates an ink droplet to eject an ink droplet from the ejection port, a portion of the piezoelectric vibrator corresponding to the ink flow path is selectively driven to form the corresponding ink flow path. An inkjet recording device characterized by causing displacement in the side walls of a flow path on both sides.