JPH05177832A - Ink jet head printing head and electronic machinery equipped therewith - Google Patents

Abstract

PURPOSE:To provide an ink jet printing head realizing still more high densification and solving a problem such as a failure of emission of ink or the lowering of printing quality. CONSTITUTION:A large number of individual ink passages 12 are formed on the surface of a photosensitive glass substrate 10 susceptible to anisotropic etching in an array form by anisotropic etching so as to extend from both ends of the glass substrate 10 to the vicinity of the central part thereof and the leading end parts 12d of the individual ink passages 12 are collectively arranged in one row at the central part of the substrate 10 and a vibration plate 20 is attached to the surface of the glass substrate 10 so as to cover all of the individual ink passages 12. A common electrode is provided on the vibration plate 20 and individual piezoelectric elements 30 are fixed on the common electrode so as to be positioned above pressure chambers and individual electrodes are provided on the individual piezoelectric elements 30. Therefore, when voltage is applied to the common electrode and the individual electrodes, the individual piezoelectric elements 30 are displaced downwardly and the corresponding parts of the vibration plate 20 are curved and deformed to reduce the ink volumes of the individual ink passages 12 and the ink of the individual ink passages 12 is pushed out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head, a printer, a word processor, and a printer including the same.
The present invention relates to electronic devices such as facsimiles and 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. As shown in FIG. 9, a Kaiser type print head generally has a large number of individual ink passages 104 each including a supply passage 101, a pressure chamber 102, and a tip portion 103 formed on a photosensitive glass substrate 100 at regular intervals. Then, a vibrating plate 110 (see FIG. 10, which is omitted for convenience in FIG. 9) is attached to the glass substrate 100 so as to cover all the individual ink passages 104, and the vibrating plate 110 positioned above the pressure chamber 102 of the individual ink passages 104. The piezo elements 120 are respectively provided at the corresponding portions. Usually, in order to increase the degree of integration, as shown in FIG. 10, the individual ink passages 104, the vibrating plate 110, and the piezo element 120 are provided on both surfaces of the glass substrate 100, and are arranged at an angle with respect to the print scanning direction. , The timing of ink ejection is controlled.

In addition, as shown in FIG. 8, on a glass substrate 100, an individual ink passage group 104A extending from one end to the vicinity of the center and an individual ink passage group 104B extending from the other end to the vicinity of the center are respectively arranged in an array. And the tip portions 103 of the individual ink passages 104 are arranged in a line in the center of the glass substrate 100, a vibrating plate (not shown in FIG. 8) is mounted on the glass substrate 100, and it is positioned on the pressure chamber 102. There is also a piezoelectric element 120 fixed to the corresponding portion of the vibrating plate.

In each of these print heads, an electric field is applied to the piezo element 120 to displace the piezo element 120, and the corresponding portion of the vibrating plate 110 is moved by this displacement to move the ink from the tip 103 of the individual ink path 104. Push it out.

[0005]

By the way, in the print head as described above, generally, a photosensitive glass substrate capable of isotropic etching is used, and individual ink paths are formed on the glass substrate by isotropic etching. Is forming. However, it is difficult to control the etching depth in isotropic etching, and in order to increase the depth of the individual ink passage,
The width of the individual ink path must be wide. On the other hand, in order to achieve high density of the print head, it is necessary to narrow the width of the individual ink passage. Therefore, the structure shown in FIGS. 8 and 10 is adopted to increase the degree of integration.

However, since isotropic etching is used, it is unavoidable that the etching depth (depth of individual ink passage) becomes shallow. In particular, in the case of forming a flow path pattern in which the intervals between the individual ink passages are narrowed in order to achieve higher density, the depth of the individual ink passages becomes smaller and smaller. In that case, the flow path resistance of the ink increases, and problems such as the inability to eject the ink and the inability to increase the driving frequency of the piezo element occur.

Further, in the isotropic etching, since the individual ink passages are inevitably shallow, the individual ink passages 104 have a semicircular cross section as shown in FIG. For this reason,
In particular, if the tip portion 103 is semi-circular, unevenness in the ink droplet shape may occur, and satellites (a phenomenon in which the ink trails when ink jumps out and ink runs out poorly) may occur, resulting in poor print quality. descend.

Therefore, an object of the present invention is to provide an ink jet print head which realizes a higher density and solves problems such as non-printing of ink and deterioration of print quality, and an electronic device including the print head. To do.

[0009]

In order to achieve the above object, an ink jet print head of the present invention comprises a photosensitive glass substrate capable of anisotropic etching, one end of which is near the center and the other end of which is centered. A large number of individual ink passages extending in the vicinity are formed in an array by anisotropic etching, and the tips of the individual ink passages are arranged in a line near the center according to the printing density to form the individual ink passages on the glass substrate. A vibrating plate is mounted on the above side so as to cover all the individual ink passages, and a vibrating plate displacing means including a piezoelectric element and an electrode for displacing a corresponding portion of the vibrating plate located on the individual ink passage on the vibrating plate. Is provided.

In the print head of the present invention, a photosensitive glass substrate capable of anisotropic etching is used, and the individual ink paths are formed by anisotropic etching. Therefore, the etching depth can be easily adjusted without being affected by the etching width. Can be controlled. Therefore, even if the width of the individual ink path is narrowed, the depth can be increased, the flow resistance of the ink does not increase, and the density of the ink can be increased without causing problems such as ink failure. realizable.

Further, in particular, since the ratio of the depth and the width of the tip of the individual ink path can be set to depth / width = 1 or more,
The unevenness of the ink droplet shape and satellites are not generated, the ink ejection capability is significantly improved, and the printing quality can be improved. Further, even in the case of narrow individual ink passages to increase the degree of integration, it is possible to gather the tip portions of the individual ink passages having a sufficient depth in the central portion of the glass substrate, resulting in higher density. Can be realized.

In the print head of the present invention, the vibrating plate is displaced by the vibrating plate displacement means to increase or decrease the ink volume of the individual ink passage and eject the ink from the individual ink passage whose ink volume has decreased. As specific diaphragm displacement means, the following modes are exemplified. Aspect: An individual piezo element fixed to a corresponding portion of the vibration plate located on the individual ink path, and electrodes provided on both surfaces of the individual piezo element for applying an electric field to the individual piezo element.

Aspect: A piezo element fixed on the vibrating plate, and an electrode for applying an electric field to the corresponding part of the piezo element provided on one or both sides of the corresponding part of the piezo element located on the individual ink path. thing. Aspect: A piezo element fixed on the vibration plate and an electrode for applying an electric field to the piezo element, which is provided on one side or both sides of the piezo element, for separating the electrode into electrodes corresponding to individual ink paths The notch is formed on one side or both sides of the piezo element.

The ratio (depth / width) of the depth and width of the tip of the individual ink passage may be 1 or more, but in practice it is about 2 (that is, the depth is twice the width). ) Is appropriate.

[0015]

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 is a plan view 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 has individual ink passage groups 12A, 1A each including an individual ink passage 12 having a flow passage pattern as shown in the drawing.
2B formed photosensitive glass substrate 10 and diaphragm 20 attached on glass substrate 10 so as to cover individual ink path groups 12A and 12B (omitted in FIG. 1, see FIG. 3)
And an individual piezo element 30 fixed to a corresponding portion of the vibration plate 20 located on the individual ink path 12.

The glass substrate 10 is capable of anisotropic etching, and the individual ink passage groups 12A and 12B are formed on the surface side of the glass substrate 10 by anisotropic etching according to the printing density. Each individual ink path group 12A, 1
In 2B, a large number of individual ink passages 12 respectively extend from one end and the other end of the glass substrate 10 to the vicinity of the center and are composed of a supply passage 12a, a pressure chamber 12b, a narrow portion 12c, and a tip portion 12d that functions as a nozzle. It In order to increase the density, the tips 12d of all the individual ink passages 12 are
The narrow portions 12c are gathered in a line in the central portion of the glass substrate 10, and accordingly, the narrow portion 12c extends obliquely from the pressure chamber 12b toward the tip portion 12d.

In the portion where the tips 12d of the individual ink passages 12 are gathered, as can be seen from FIG. 2 which shows an enlarged view of the portion surrounded by the circular solid line X in FIG. 1, the tips from the groups 12A and 12B ( The shaded portions) 12d are alternately arranged at a constant pitch, and these tip portions 12d are exposed on the front surface side of the glass substrate 10. The individual ink passages 12 of each of the groups 12A and 12B communicate with a common ink passage (not shown) formed at one end and the other end of the glass substrate 10, respectively, and ink is supplied from the common ink passage. After passing through 12a, the pressure chamber 12b, and the narrow portion 12c, it flows to the tip portion 12d.

In FIG. 3, the diaphragm 20 attached to the front surface side of the glass substrate 10 has a hole 21 having a circular cross section which communicates with each tip 12d. In this embodiment, the vibrating plate 20 also serves as the nozzle plate, and the holes 21
Since the cross-sectional shape of is a circle, the ink droplet becomes a stable spherical shape, and the printing quality is further improved. The individual piezo element 30 fixed on the vibration plate 20 is located on the pressure chamber 12b of the individual ink passage 12 and has substantially the same size as the planar shape of the pressure chamber 12b. Although not particularly shown in FIGS. 1 and 3, ITO is provided on the upper surface of the vibration plate 20 located on the pressure chamber 12b of the individual ink passage 12 of each group 12A, 12B.
And the like, and a common electrode is provided on the upper surface of the individual piezo element 30.

As described above, if anisotropic etching is used, the etching depth can be increased irrespective of the etching width. Therefore, as shown in FIG. 4, the depth d and the width w of the individual ink passage 12 are increased. By setting the ratio of and to d / w = 1 or more, the cross-sectional shape can be made rectangular. As a result, the individual ink passage 12 includes the supply passage 12a and the pressure chamber 12
The depth is constant over b, the narrow portion 12c, and the tip portion 12d. Therefore, the width of the individual ink passage 12 can be narrowed to increase the density, and especially the tip portion 12d.
The pitch can be reduced to about 0.1 mm.
Incidentally, when isotropic etching is adopted, as shown in FIG. 7, the cross-sectional shape of the individual ink passage 104 is a semicircle, and the ratio d / w between the depth d and the width w is smaller than 1. Therefore, the pitch of the tip is limited to about 0.2 mm.

The operation of the print head will be briefly described. In FIG. 5 showing an enlarged cross-sectional view of the main part taken along the line AA of FIG. 1, the common electrode 31 provided on the upper surface of the diaphragm 20
When a voltage having an appropriate polarity is applied to the individual electrode 32 provided on the upper surface of the individual piezoelectric element 30, the individual piezoelectric element 3
An electric field is applied to 0, and this element 30 is displaced toward the diaphragm 20. Due to this displacement, the corresponding portion of the vibration plate 20 located on the pressure chamber 12b is pressed downward to be curved / deformed. Then, the ink volume of the pressure chamber 12b decreases,
The ink filled in the pressure chamber 12b is pushed, passes through the narrow portion 12c and the tip portion 12d, and then the corresponding hole 2 of the vibration plate 20.
1 is ejected perpendicularly to the surface of the glass substrate 10.

FIG. 6 shows another embodiment. In this print head, individual ink passage groups 42A and 42B including a large number of individual ink passages 42 having a flow passage pattern as shown in FIG.
Only the tip 42d of No. 2 penetrates the glass substrate 40 and appears on the front surface side of the substrate 40. The tip portion 42d is
Similar to the previous embodiment, the glass substrates 40 are arranged in a line in the central portion on the front surface side. A vibrating plate 50 is attached to the back surface side of the glass substrate 40 so as to cover all the individual ink passages 42, and the individual piezo element 60 is provided at a corresponding portion of the vibrating plate 50 located above the pressure chamber of the individual ink passages 42. Is stuck. In this embodiment, the tip portion 42d directly functions as a nozzle, and the glass substrate 40 also serves as a nozzle plate. Of course, although not shown in the drawing, a common electrode is provided at a corresponding portion of the vibration plate 50 located on the pressure chamber of the individual ink passage 42, and an individual electrode is provided on the individual piezoelectric element 60.

The print head of FIG. 6 is also no different in operation from the above embodiment. That is, a voltage is applied to the common and individual electrodes to apply an electric field to the individual piezo element 60 to displace it. Then, the corresponding portion of the vibration plate 50 is deformed to push out the ink in the individual ink passage 42. The above embodiments are merely examples of the book, and may be variously modified without departing from the object of the present invention. For example, in the above embodiments, the diaphragm displacement means is related to the above aspect, but the common electrode on the diaphragm is also separated into individual electrodes,
Both sides of the piezo element may be used as individual electrodes.

Alternatively, one piezo element is fixed on the vibrating plate located on the pressure chambers of all the individual ink passages of each individual ink passage group, and one side of the corresponding portion of the piezo element located on each pressure chamber is fixed. Alternatively, electrodes may be provided on both surfaces [the above embodiment]. Alternatively, similarly, one piezo element is fixed on the vibration plate located on the pressure chamber, an electrode is provided on one side or both sides of the piezo element, and a notch for separating the electrode into electrodes corresponding to each pressure chamber is provided. It may be formed on one side or both sides of the piezo element [the above embodiment]. These aspects,
In the case of, since only one piezo element is required, productivity is increased. Further, in this case, it is possible to use the lower surface of the piezo element (that is, the vibration plate) as an individual electrode and the upper surface of the piezo element as a common electrode.

[0024]

As described above, the ink jet print head according to the present invention has a large number of individual ink passages extending from one end and the other end of the photosensitive glass substrate, which are anisotropically etched, to the vicinity of the center. Since it is formed by reactive etching, it has the following effects. (1) Since the etching depth can be controlled independently of the etching width, the depth can be increased even if the width of the individual ink path is narrowed, and moreover, with a single glass substrate. A very large number of individual ink paths can be integrated, and high density can be realized. (2) Even in the case of a narrow individual ink path, the depth can be increased to increase the cross-sectional area of the individual ink path, so the ink flow resistance does not increase. Therefore, the ink does not run out and the drive frequency can be increased. (3) As shown in FIG. 1, by arranging the narrow individual ink passages in an array form and ensuring a sufficient depth of the ink passages, the leading ends of the individual ink passages can be gathered in a line in the central portion of the glass substrate. In spite of the high degree of integration, control of ink ejection is easy. (4) Since the ratio of the depth to the width at the tip of the individual ink path is set to depth / width = 1 or more and the cross-sectional shape of the tip can be made into a rectangular shape, the shape of the ink droplet is uneven. Printing quality is improved without any occurrence of satellites or satellites. (5) If the vibrating plate displacing means is in the above-described mode, one piezoelectric element is sufficient for each individual ink path group, and this is substantially an individual piezoelectric element by patterning or forming notches on the electrodes. As a result, the productivity is improved, the quality of the piezo element is stable, and a small and inexpensive print head can be provided as compared with the case where the individual piezo element is attached to each individual ink path. (6) Further, by attaching a nozzle plate having a circular cross-section hole communicating with the tip of the individual ink passage to the glass substrate, the ink droplet becomes a stable spherical shape, and the printing quality is further improved.

[Brief description of drawings]

FIG. 1 is a plan view of a print head according to an exemplary embodiment of the present invention.

FIG. 2 is an enlarged view of a portion surrounded by a circular solid line X in FIG.

FIG. 3 is a longitudinal sectional view of a main part of the print head of FIG.

FIG. 4 is a cross-sectional view illustrating a cross-sectional shape of individual ink paths in the print head of the present invention.

5 is an enlarged cross-sectional view of a main part taken along the line AA in FIG.

FIG. 6 is a vertical cross-sectional view of a main part of a print head according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view of an individual ink passage in a conventional example for comparison with FIG.

FIG. 8 is a plan view of a print head according to a conventional example.

FIG. 9 is a partially omitted plan view of an ordinary Kaiser type print head.

FIG. 10 is a side view of the print head shown in FIG. 9 with a part thereof omitted.

[Explanation of symbols]

 10, 40 Photosensitive glass substrate 12, 42 Individual ink path 20, 50 Vibration plate 30, 60 Individual piezo element 31 Common electrode 32 Individual electrode

Front page continuation (72) Inventor Kyo Ema, 21, Saiin Mizozaki-cho, Ukyo-ku, Kyoto City, ROHM Co., Ltd. Shinsaku 21, Mizozaki-cho, Saiin, Ukyo-ku, Kyoto ROHM Co., Ltd.

Claims (7)

[Claims] 1. A photosensitive glass substrate capable of anisotropic etching, wherein a large number of individual ink passages extending from one end to the vicinity of the center and from the other end to the vicinity of the center are formed in an array by anisotropic etching. , According to the print density, the tip of the individual ink path is arranged in a line in the vicinity of the center, and a vibration plate is attached to the side of the glass substrate where the individual ink path is formed so as to cover all the individual ink paths. An ink jet print head characterized in that a vibrating plate displacing means including a piezo element and an electrode for displacing a corresponding portion of the vibrating plate located on the individual ink path is provided on the upper side. 2. The ink jet print head according to claim 1, wherein the tip ends of the individual ink passages are gathered in the central portion of the glass substrate. 3. The tip portion of the individual ink passage has a cross-sectional shape in which the ratio of the depth to the width of the individual ink passage is depth / width = 1 or more. The described inkjet printhead. 4. A nozzle plate having a circular cross-section hole communicating with the tip of the individual ink passage is attached to the surface of the glass substrate where the tip of the individual ink passage exists. 4. The inkjet printhead according to any one of 3 above. 5. The individual ink passage is formed on the front surface side of a glass substrate, and the tip of the individual ink passage is exposed on the front surface side of the glass substrate. Inkjet printhead according to the item. 6. The individual ink passage is formed on the rear surface side of the glass substrate, and the tip of the individual ink passage is exposed on the front surface side of the glass substrate. Inkjet printhead according to the item. 7. An electronic apparatus comprising the ink jet print head according to claim 1. Description: