JPH02297445A - Ink discharger of ink jet printer - Google Patents

Abstract

PURPOSE:To obtain high recording density by application of coulomb force by a method wherein a thin film electrode is formed on both left and right side walls of an ink chamber which is formed from a silicon signal crystal block to which the ink chamber having both left and right side walls in a direction of a 111 crystal face and an orifice are provided. CONSTITUTION:A plurality of ink chamber 12 and orifices 13 are in a parallel formed in a silicon block 11 of cutting a silicon signal crystal wafer out to a rectangular parallelepiped. The silicon block 11 is so made that its upper end surface 11a becomes a 110 crystal face and a side face 11b parallel to a side wall of the ink chamber 12 becomes a 111 crystal face. Further, a several micron thin film electrode 14 is formed by vapor deposition between the side wall of the ink chamber 12 and an adjacent ink chamber 12 on the upper end surface 11a. Therefore, when voltage is impressed with polarity between the thin film electrodes 14 on both left and right side walls of the ink chamber 12, coulomb force in a C direction acts between the thin film electrodes 14, and the side wall is deformed to decrease its sectional area. Ink in the ink chamber 12 is pushed out and is discharged from the orifice 13. High dense high speed recording can be performed thereby.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an ink ejection device for an inkjet printer, and particularly to an ink ejection device for an inkjet printer that achieves high density recording by miniaturizing ink chambers and orifices. It is related to.

[Prior Art] Inkjet printers are used as powerful recording devices because they are capable of high-speed recording and can also record on plain paper without special fixing processing.

In order to improve the quality of images recorded by inkjet printers, higher density recording is required.

As an important factor for increasing recording density, first of all, it is required that the recording dot shape be small. Furthermore, as the dot shape of recording becomes smaller, in order to obtain a desired recording speed, the nozzles themselves that eject ink must be easily highly integrated.

2. Description of the Related Art Conventional inkjet printer ink ejecting apparatuses for increasing the printing density include those shown in FIGS. 5 to 7.

The conventional ink ejecting device shown in FIG. 5 has a piezoelectric actuator 2 made of piezoelectric ceramics and having a nozzle 1 formed therein as its main body. The piezoelectric actuator 2 includes upper and lower piezoelectric blocks 2a, 2. b, and a plurality of nozzles 1 are formed side by side across the top and bottom of the bonding layer 3. On the inner wall of the ink chamber 1, there is a sixth
As shown in the figure, a thin film electrode 4 is formed. Also,
A thin film electrode pattern 4 is formed on the rear upper surface of the lower piezoelectric block 2b, and a piezoelectric actuator driving IC 5 is bonded thereon.

The operation of the conventional ink ejection device formed in this way will be described below. The piezoelectric actuator 2 is driven using the piezoelectric shear mode shown in FIG. Referring to the figure, when a voltage is applied between the left and right side walls 7 and 8 of the piezoelectric body 6 polarized in the direction of arrow A, a mode deformation occurs as indicated by a two-dot chain line in the figure. In the ink chamber of the piezoelectric actuator 2, by applying a voltage between the electrodes, deformation due to this piezoelectric shear mode occurs vertically symmetrically in the bonding layer 3, as shown in FIG. As a result, the side wall of the ink chamber 1 is deformed into a dogleg shape, and ink is forced out of the ink chamber 1 whose side wall is deformed inward, as in the ink chamber 1a in the center of FIG. The extruded ink flows through an orifice plate (
The ink is discharged to the outside through an orifice corresponding to each ink chamber formed in the ink chamber (not shown). This kind of behavior
This occurs selectively in each ink chamber 1 by the drive circuit 5 in response to a recording signal, and a recorded image is formed on a recording paper (not shown) facing the outlet of the ink chamber 1.

[Problems to be Solved by the Invention] However, the above conventional ink ejection device has the following problems.

Methods for forming the ink chambers in the piezoelectric blocks 2a and 2b include cutting with a dicing saw, metal film formation by electroforming, laser processing, and wet etching. However, no matter which of these processing methods is used, in terms of processing accuracy and mass productivity,
Grooving with a width of about 30 microns is the practical limit.

Therefore, when applied to an ink ejection device, the recording density is 400 dpi (dots per 1n
ch) is the limit, and good image quality cannot be obtained.

Furthermore, there has been a conventional concept of forming an electrode on the side wall of the ink chamber and applying a pulse voltage thereto to cause the volume of the ink chamber to contract due to Coulomb force, thereby causing ink to be ejected. This method has the advantage that it can be driven with good responsiveness without using a piezoelectric element and with comparatively low energy. However, in order to obtain a predetermined recording density by applying Coulomb force, it is necessary to form an extremely elongated cross-sectional shape and a fine ink chamber, which is difficult to achieve using conventional processing methods. There is.

In order to solve the above-mentioned conventional problems, it is an object of the present invention to provide an ink ejection device for an ink jet printer that applies Coulomb force and has a fine structure for obtaining high recording density.

[Means for Solving the Problems] The ink ejection device of the inkjet printer of the present invention has the following features:
Both are made of a silicon single crystal block having an ink chamber and an orifice having left and right side walls in the direction of the (111) crystal plane.

Thin film electrodes are formed on both left and right walls of the ink chamber.

In addition, the ink ejection device of the inkjet printer of the present invention includes a silicon monocrystalline block on either end surface.
This includes those in which a drive circuit for controlling the drive of the ink chamber is directly formed.

[Operation] According to the present invention, (111
) By configuring the ink chamber and orifice to have side walls in the direction of the crystal plane, so-called anisotropic etching can be applied to the formation of the ink chamber and orifice. In other words, (111
/) Taking advantage of the fact that the etching rate in the crystal plane direction is several tens of times higher than in other crystal plane directions, ink chambers and orifices are formed by processing deep and fine grooves in the (111) crystal plane direction. be done. As a result, it is possible to fabricate an ink chamber with a deep and elongated cross-sectional shape that causes the contraction of the crystal chamber necessary to eject ink due to the Coulomb force when a pulse voltage is applied to the thin film electrode formed on the side wall of the ink chamber. become.

Furthermore, since the ink chamber and orifice are formed in a silicon single crystal block, it is possible to directly form a drive circuit for controlling the drive of the ink chamber on the end face of the block itself.

[Example] An example of the present invention will be described below based on FIGS. 1 to 4.

The main body of the ink ejection device of this embodiment is as shown in FIG. Referring to the figure, a plurality of ink chambers 12 and orifices 13 are formed in parallel in a silicon block 11 obtained by cutting a silicon single crystal wafer into a rectangular parallelepiped.

The silicon block 11 has an upper end surface 1.1 a of (1
10) Crystal plane, side surface 1 l parallel to the side wall of the ink chamber 12
(1,:1.:l-) so that b is the (1,:1.:l-) crystal plane.
1,0) Use a material cut out from a wafer. The reason why the crystal orientation of the silicon block 11 is selected in this way is that the grooves for forming the ink chamber 12 and the orifice 13 are
This is because so-called anisotropic etching takes advantage of the difference in etching characteristics depending on the crystal orientation of silicon. In other words, the etching rate in the (111) crystal plane direction is several tens of times faster than the etching rate in the (110) plane direction.
This takes advantage of the fact that it is twice as fast. Grooving of the ink chamber 12 and orifice 13 is carried out by forming a mask corresponding to the horizontal cross-sectional shape on the upper end surface 1 of the silicon block 11, and performing wet etching or the like. can be done.

By using such anisotropic etching, the width 1
It is possible to process grooves with a diameter of 0 microns, a depth of 100 microns, and a pitch of about 40 microns. Thereby, the degree of integration of orifices can be increased to about 600 dpi.

A thin film electrode 14 having a thickness of several micrometers is formed by vapor deposition on the side wall of the ink chamber 12 and between adjacent ink chambers 12 on the upper end surface 11a, as shown in the cross section of FIG. When a voltage is applied between the thin film electrodes 14 on the left and right side walls of the ink chamber 12 in a curved configuration as shown in FIG. becomes smaller. As a result, the ink in the ink chamber 12 is pushed out and ejected from the orifice 13. By applying this voltage in accordance with the recording signal,
A desired recorded image will be obtained.

In the recording method of the ink ejection device of this embodiment, the energy required for recording is significantly reduced compared to a conventional method using a piezoelectric body. Specifically, whereas the conventional method requires recording energy of 10-5 Joule/dot or more, in this embodiment, recording energy of 10"-8 to 10-' Joule/dot or more is required.
/dot.

In this embodiment, each ink chamber 12 receives a recording signal.
A drive circuit 15 that controls the drive of the silicon block 1
1 is directly formed on the upper end surface 11a of 1. The reason why the drive circuit 15 can be directly formed in this manner is that the actuator portion of the ink discharge device having the ink chamber 12 and the orifice 13 is formed of silicon crystal. As a result, there is no need to bond the drive circuit IC as in the conventional case, and it is possible to achieve compactness and unitization of the actuator section.

When the ink ejection device of this embodiment is in use, as shown in FIG. 3, the upper end surface of the cylinder block 11]
]-a is tightly covered with cover plate ]6. Further, a part of the front surface where the orifice 13 opens is covered with a mask plate 17, so that only the lower part of the orifice is opened so that ink droplets of an appropriate size can be ejected.

When the ink ejection device of this embodiment is incorporated into an inkjet printer, it is arranged as schematically shown in FIG. Referring to the figure, first, ink 20 is supplied from the ink cartridge 18 through the ink filter 19 into the ink chamber.

When a recording signal is input to the signal terminal 21, the drive circuit 15 operates in response to the recording signal, and the ink chamber 1 is activated in response to the recording signal.
2 is driven. As a result, ink droplets ejected from the orifice 13 adhere to the recording paper 23 running along the platen 22, forming a recorded image.

In this embodiment, the drive circuit 15 is provided on the upper end surface 11a of the silicon block 11, but it may be formed on other end surfaces such as the side surfaces as required.

[Effects of the Invention] As described above, according to the present invention, the ink chamber and the orifice are provided with the side wall in the direction of the (111) crystal plane of the block made of silicon single crystal. Microfabrication using anisotropic etching can be applied to the formation of. This results in
A method in which a pulse voltage is applied between thin film electrodes formed on the side wall of an ink chamber to cause the ink chamber to contract due to Coulomb force and eject ink can be applied as an ink ejection device of an inkjet printer.

Therefore, ink ejection can be controlled with good responsiveness with relatively low energy, and high-density and high-speed recording can be realized.

In addition, by directly forming a drive circuit for controlling the drive of the ink chamber on either end face of a block made of silicon single crystal, there is no need to separately bond a drive circuit IC to the actuator part as in the past. .

As a result, it is possible to achieve compactness, facilitate high integration, and improve image quality as recording density increases.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing the structure of an ink ejection device of an inkjet printer according to an embodiment of the present invention, Fig. 2 is a sectional view taken along line BB in Fig. 1, and Fig. 3 is a perspective view of the device in use. 4A and 4B are diagrams showing a schematic configuration of the same device when it is incorporated into an inkjet printer. FIG. 5 is a perspective view showing an example of an ink ejecting device of a conventional inkjet printer, and FIGS. 6 and 7 are enlarged sectional views of essential parts for explaining the operating principle of the device. In the figure, 11 is a silicon block, 12 is an ink chamber, 13 is an orifice, 14 is a thin film electrode, and 15 is a drive circuit. = 13-

Claims (2)

[Claims] (1) Consisting of a silicon single crystal block provided with an ink chamber and an orifice, both of which have left and right side walls in the direction of the (111) crystal plane, and thin film electrodes are formed on each of the left and right side walls of the ink chamber. Features of inkjet printer ink ejection device. (2) An inkjet printer according to claim 1, wherein a drive circuit for controlling the drive of the ink chamber by applying a pulse voltage to the thin film electrode is directly formed on one end face of the block. Discharge device.