JPH0538808A - Ink jet print head and electronic equipment equipped with the same - Google Patents

Abstract

PURPOSE:To provide an inexpensive ink jet print head which can embody a high density and high quality printing, and at the same time, has a favorable productivity, and in addition, can use a high viscous ink; and an electronic equipment equipped with the print head. CONSTITUTION:Individual ink passages 11 which go through diagonally from one end surface of the other end surface of a head base 1 are formed in an alley shape with uniform intervals on the heat base. A sidewall displacing means which consists of a common electrode 14, a piezoelectric body 15, an individual electrode 16 and a protective film 17 is provided on a sidewall surface 13a and the rear end surface 13c of the head base 1 (including the rear end surface of a sidewall 12) among wall surfaces which become the contour of the individual ink passage 11, and the sidewall displacing means is not provided on a sidewall surface 13b. Therefore, when a voltage is applied on the common and individual electrodes 14, 16, the piezoelectric body 15 to which an electric field is added is displaced to the alley direction by the polarization electrical charge of the piezoelectric body 15 and the voltage polarity of the electrodes 14, 16, and the corresponding sidewall 12 deforms to the alley direction, accompanying with the displacement.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel ink jet print head for ejecting ink by changing the ink volume of an individual ink passage by utilizing the displacement of a side wall displacing means, and a printer, a word processor and a facsimile including the same. , Electronic devices such as plotters.

[0002]

2. Description of the Related Art There is a Kaiser system for an ink jet print head mounted on various electronic devices such as printers and word processors. In the Kaiser type print head, a vibration plate is generally attached to the head base so as to cover the individual ink passages branched from the common ink passage formed on the head base, and piezoelectric plates are respectively provided at corresponding positions of the individual ink passages on the vibration base. The body is arranged. In this print head, an electric field is applied to the piezoelectric body to displace the piezoelectric body, and the vibration plate is moved in accordance with this displacement to push out ink from the tip end port of the individual ink path. Further, the head itself is tilted with respect to the scanning direction to increase the density and quality of printing.

[0003]

However, in an ordinary ink jet print head using a piezoelectric material represented by the Kaiser system as described above, the density of printing dots is increased and the quality of printing is improved more than ever. It is mechanically difficult to do so, and if it is attempted to realize a higher density, the productivity will deteriorate and the cost will increase. In addition, in order to improve printing quality, it is required to use high-viscosity ink in addition to high density. To do this, the individual ink paths should be as short as possible to reduce the fluid friction of the ink. Without it, the ink cannot be ejected. However, it is difficult to use high-viscosity ink in the print head because it is difficult to further shorten the individual ink path. Further, it is necessary to give sufficient consideration to measures against ink clogging, but if the individual ink path is long, the measures will be serious.

Therefore, an object of the present invention is to provide an inexpensive ink jet print head which realizes high density and high quality of printing, has good productivity, and can use high viscosity ink, and this print head. To provide an electronic device.

[0005]

In order to achieve the above-mentioned object, the ink jet print head of the present invention has a head base having a fixed individual ink path extending obliquely from one end surface to the other end surface of the head base. A piezoelectric body is formed on a common electrode and an individual electrode on at least one side wall surface which is formed in an array shape at intervals and which is a contour of the individual ink path and extends along at least a direction perpendicular to the ink flow direction and the array direction. It is characterized in that the side wall displacing means sandwiched between is provided, and the side wall displacing means is not provided on the other side wall surface along the vertical direction.

In the print head of the present invention, the side walls formed by the individual ink passages arranged in an array are displaced in the array direction by the side wall displacement means to change the ink volume of the individual ink passages, and the ink of the individual ink passages is changed. It incorporates a new printing mechanism that pushes out. This printing mechanism will be described in detail. The piezoelectric body of the side wall displacement means is polarized, for example, in the array direction, and in this polarized state, for example, a proper polarity is applied to the common electrode on one side (side wall surface side) of the piezoelectric body. When a voltage of the opposite polarity to the above-mentioned polarity is applied to the individual electrode on the other side (individual ink path side) of the piezoelectric body, the electric field depending on the positive / negative charge of polarization and the positive / negative polarity of the voltage is applied. The piezoelectric body added with is displaced in the array direction, and as a result, the corresponding side wall is also displaced in the array direction along with the displacement of the side wall displacement means, and the volume of the individual ink passage is changed.

More specifically, for example, when the side wall surface side of the piezoelectric body is polarized positively and the opposite side (individual ink path side) is polarized negatively, a positive voltage is separately applied to the common electrode. When a negative voltage is applied to the electrodes, the piezoelectric body contracts in the array direction, and the side wall displacing means having the piezoelectric body deforms the corresponding side wall into a shape that closes the individual ink path. When the side wall is deformed, the ink volume of the individual ink passage on the side subject to the deformation is reduced and the ink volume of the individual ink passage on the opposite side is increased. By appropriately performing the increase / decrease in the ink volume, the ink in the individual ink passage converted into the volume decrease is pushed and ejected from the tip end orifice (orifice) of the individual ink passage. As described above, the print head of the present invention has the effect of pushing out the ink in the individual ink passages by largely displacing the side wall in the array direction in accordance with the displacement of the piezoelectric body in the array direction and changing the ink volume. Have.

In the print head of the present invention, as the piezoelectric material forming the side wall displacement means, a known piezoelectric material may be used, for example, a piezoelectric material made of PZT or ZnO. The piezoelectric body is polarized in the array direction on the side wall surface of the individual ink path, but in the case of PZT, it is appropriate to perform this polarization after providing the side wall displacement means on the side wall. Further, in the case of ZnO, polarization is naturally performed (axially oriented) during film formation by sputtering or the like.

The head base used in the print head of the present invention is not limited in material as long as the side wall formed by the individual ink path is displaced in the array direction by the displacement of the piezoelectric body. However, in practice, photosensitive glass or the like is the best material as a raw material because of the ease of forming array-shaped individual ink passages, the ease of displacement of the side walls, and the like.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The ink jet print head of the present invention and electronic equipment equipped with the same will be described below based on embodiments. FIG. 1 shows a cross-sectional view in the front-rear direction of an embodiment of a print head mounted on an electronic device such as a printer or word processor. The structure of electronic devices other than the print head is not much different from usual, and the print head will be mainly described here. The print head shown in FIG. 1 includes a head base 1 and
Orifice plate 2 attached to the front end face of head base 1
And a back cover 3 attached to the rear end surface of the head base 1.

A front view of the head base 1 is shown in FIG. 2, and a sectional view taken along line AA of FIG. 2 is shown in FIG. As can be seen from FIGS. 2 and 3, the head base 1 has one end surface (rear end surface) thereof.
A plurality of (nine in this embodiment) individual ink passages 11 obliquely penetrating from the other end surface (front end surface) to each other are formed in an array at regular intervals. Therefore, the individual ink passages 11 open on the front end face and the rear end face of the head base 1. The individual ink passages 11 form a plurality of (eight in this embodiment) side walls 12 between the individual ink passages, and the side walls 1 are naturally formed.
2 extends upright along the individual ink paths 11. or,
The individual ink passage 11 and the side wall 12 have a rectangular shape in both plane and cross section.

In this embodiment, as shown in FIG. 2, the lower side of the side wall 12 is continuous with the head base 1, but the upper side is separated from the head base 1 with a slight gap. By doing so, the side wall 12 is in a so-called cantilevered state in which the lower side is the fixed end and the upper side is the free end, and the upper side wall 12 is more than the cantilever beam continuous to the head base 1. Is not only easily displaced, but also the displacement amount is increased by 16 times or more.

As shown in detail in FIG. 3, the individual ink paths 11
Among the wall surfaces that are the outlines of the above, one side wall surface 13a along the direction perpendicular to the ink flow direction and the array direction and the rear end surface of the head base 1 (including the rear end surface of the side wall 12) 13c are common. An electrode 14, a piezoelectric body 15, an individual electrode 16, and a protective film 17 are sequentially provided, and these four elements 14, 1
5, 16 and 17 form a side wall displacement means. The side wall displacing means includes the other side wall surface 13 along the vertical direction.
It is not provided in b. Therefore, each side wall displacement means
Each is continuous from the side wall surface 13a of the individual ink passage 11 to the rear end surface 13c of the head base 1. The side wall displacement means is omitted in FIG.

Although not shown in the drawing, the common electrode 14 and the individual electrode 16 are designed so that a voltage can be applied from the rear end face of the head base 1, and the side wall displacement means can be individually operated. .. The protective film 17 prevents the common and individual electrodes 14 and 16 from being short-circuited when a conductive ink is used, and also has a role of protecting the electrodes 14 and 16 and the piezoelectric body 15.

Head base 1 in which individual ink passages 11 are open
The orifice plate 2 attached to the front end face of the device closes all the individual ink passages 11 from the front end face side, and has the number (9) of orifices 21 corresponding to the individual ink passages 11 (see FIG. 4). ). Further, the back cover 3 provided on the rear end face of the head base 1 closes all the individual ink passages 11 from the rear end face side and has an ink supply passage 31 communicating with all the individual ink passages 11. Therefore, the ink is divided into the individual ink passage 11 via the ink supply passage 31, and is ejected from the orifice 21.

Next, the operation of the print head thus constructed will be described. In FIG. 3 showing an enlarged cross-sectional view of the main part and FIG. 5 showing the operation of the side wall 12 (the side wall displacing means is not shown), the portions along the side wall surface 13a of each piezoelectric body 15 are positive on the side wall surface 13a side. It is assumed that the charge and the opposite side (the side of the individual ink passage 11) are polarized as a negative charge. In this polarized state, for example, the individual ink paths 11a
When a positive voltage is applied to the common electrode 14 and a negative voltage is applied to the individual electrode 16, the piezoelectric body 15 has a positive charge polarization and a positive voltage of the common electrode 14 on the side wall surface 13a side. And the relationship between the polarization of the negative charge and the negative voltage of the individual electrode 16 on the side of the individual ink path 11a reduces in the array direction (the horizontal direction in the drawing). Due to the displacement of the side wall displacement means based on the reduction of the piezoelectric body 15, the side wall 12 (particularly the upper portion which is the free end) is pushed rightward in the drawing, and is inclined toward the individual ink passage 11a adjacent to the right side of the side wall 12. (See the dotted line in FIG. 5). As a result, the ink volume of the individual ink passage 11a is substantially reduced, so that the ink of the individual ink passage 11a is pushed and ejected from the corresponding orifice 21 of the orifice plate 2.

After ejecting the ink, the applied voltage is cut off, or
Alternatively, when the polarity of the applied voltage is reversed, the piezoelectric body 15 returns to the original state when the voltage is cut off. In the case of voltage polarity reversal, the piezoelectric body 15 has an action opposite to the above action. That is, the piezoelectric body 15 is polarized by the positive charge polarization on the side wall surface 13a side and the negative voltage of the common electrode 14, and by the negative charge polarization on the individual ink path 11a side and the positive voltage of the individual electrode 16. , Stretch in the array direction.
The extension of the piezoelectric body 15 causes the side wall 12 to be tilted to the left in the drawing. In either case, since the ink volume of the individual ink passage 11a starts to increase, the ink is newly filled in the individual ink passage 11a.

In the above-mentioned embodiment, the side wall 12 is inclined rightward to reduce the ink volume in the individual ink passage 11a, thereby pushing out the ink. Direction of the individual ink path 1 by utilizing the recoil caused by returning to the right direction.
The ink 1a may be pushed out. in this case,
First, a negative voltage is applied to the common electrode 14 and a positive voltage is applied to the individual electrode 16 to tilt the side wall 12 to the left. Then, the ink volume of the individual ink passage 11a increases, so that the individual ink passage 11a is filled with ink. Next, when a positive polarity voltage is applied to the common electrode 14 and a negative polarity voltage is applied to the individual electrode 16, the side wall 12 tilts to the right, and the ink volume of the individual ink passage 11a decreases. When the ink volume is reduced, the ink is pushed and pushed out from the corresponding orifice 21.

As described above, in the print head of the present invention, the side wall displacing means (including the protective film 17) formed on the side wall 12 and including the common and individual electrodes 14 and 16 and the piezoelectric body 15 is used to move the side wall. By deforming 12, the ink volume of the individual ink passage 11 is increased or decreased to eject the ink. Therefore, the side wall displacement means for moving the side wall 12 is important in operation. This side wall displacement means is used as the side wall 12
In order to provide the same, the common and individual electrodes 14, 16 and the piezoelectric body 15 and the protective film 17 are patterned by sputtering, vapor deposition or the like to a required thickness, and then the piezoelectric body 15 is formed to a predetermined thickness. Polarize in the direction. In order to bring the polarization into the polarization state described in the above operation, for example, in FIG. 6 showing the rear end face side of the head base 1, a positive voltage is applied to the common electrode 14 ′ which is guided from the common electrode 14 and wired at both ends. Then, a negative voltage may be applied to the individual electrodes 16 ′ extending from the individual electrodes 16.

FIG. 7 shows another embodiment. This example
The side wall 112 formed by the individual ink passages 111 is in the form of a doubly supported beam, and the side wall 112 is continuous with the head base 101 on both the upper and lower sides, but the other structure is exactly the same as that of the above embodiment. Is. Therefore, the head base 1
The cross-sectional view taken along the line BB of 01 is the same as the cross-sectional view shown in FIG. 3. Therefore, when a voltage is applied to the common and individual electrodes 14 and 16 in exactly the same manner as in the above-mentioned embodiment, the piezoelectric body 15 is displaced. Since the upper and lower sides of the side wall 112 are fixed, the side wall 112 is curved as shown by the dotted line in the figure. The deformation of the side wall 112 increases the ink volume of the individual ink passage 111a and decreases that of the individual ink passage 111b. The action of pushing out the ink by utilizing this increase and decrease is as described above. The polarization of the piezoelectric body 15 in this embodiment may be performed as described above with reference to FIG. 6, and this polarization is shown in FIG.

In the print head having such a structure, the depth of the individual ink path (the dimension in the direction perpendicular to the ink flow direction and the array direction) and the length of the individual ink path (the dimension in the ink flow direction) are determined. , And each can be 1 mm or less, and the individual ink path can be greatly shortened. Therefore, high-viscosity ink can be used without any trouble. In particular, it is possible to easily provide a so-called long head in which the depth of the individual ink passage is larger than its length, and it is possible to put the line-type print head into practical use.

[0022]

Since the ink jet print head of the present invention is constructed as described above, by applying a voltage of an appropriate polarity to the common and individual electrodes of the side wall displacement means, the positive and negative electric charges of the polarization in the piezoelectric body can be obtained. Depending on the positive and negative polarities of the applied voltage, the piezoelectric body to which an electric field is applied is displaced in the array direction, and the corresponding side walls are also largely deformed in the array direction, resulting in a change in the ink volume of the individual ink paths (increased or decreased). )
However, it is an epoch-making thing that the ink in the individual ink path whose volume has decreased is pushed out.

Therefore, the print head of the present invention can easily realize high density and high quality printing. Further, since it can be mass-produced by using the existing technology and manufacturing process, the productivity is very high and the price is low. Further, since the individual ink paths can be considerably shortened (the dimension in the direction perpendicular to the ink flow direction and the array direction is larger than the dimension in the ink flow direction), high viscosity ink can be used.

In addition, since the individual ink path has a dimension in the ink flow direction shorter than the dimension in the direction perpendicular to the ink flow direction and the array direction, it is suitable for a line type print head in which many dots are arranged. .. Moreover, since the size of the individual ink passages in the ink flow direction can be shortened, it is easy to prevent ink clogging.

As a result, it is possible to obtain the effects of high quality printing, improvement of printing performance, and the like, even in an electronic device equipped with the above print head.

[Brief description of drawings]

FIG. 1 is a cross-sectional view in the front-rear direction according to an embodiment of a print head of the present invention.

FIG. 2 is a front view of a head base of the print head shown in FIG.

3 is a partially omitted cross-sectional view taken along line AA of the head base shown in FIG.

FIG. 4 is a front view of an orifice plate of the printhead shown in FIG.

FIG. 5 is a front view for explaining the operation of the side wall of the head base.

FIG. 6 is a rear view for explaining polarization of the piezoelectric body in the side wall displacement means provided on the side wall surface of the head base.

7 is a front view of a head base according to another mode of the head base shown in FIG.

8 is a rear view for explaining polarization of the piezoelectric body in the side wall displacement means provided on the side wall surface of the head base shown in FIG.

[Explanation of reference numerals] 1, 101 Head base 2 Orifice plate 3 Back cover 11, 111 Individual ink passage 12, 112 Side walls 13a, 13b Side wall surface 14 Common electrode 15 Piezoelectric body 16 Individual electrode

Claims (2)

[Claims] 1. A head base is formed with an array of individual ink passages obliquely penetrating from one end surface to the other end surface of the head base at regular intervals in an array form, and among the wall surfaces that are contours of the individual ink passages. , At least one side wall surface along a direction perpendicular to the ink flow direction and the array direction is provided with a side wall displacement means formed by sandwiching a piezoelectric body between a common electrode and an individual electrode, and the other side along the vertical direction. An ink jet print head characterized in that a wall displacement means is not provided on the wall surface. 2. An electronic apparatus comprising the ink jet print head according to claim 1.