JPH07108687A - Inkjet recording head - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce an attitude error of an ink jet recording head having a plurality of nozzle opening arrays and to simplify an ink flow path from an ink supply port to a reservoir. [Structure] Flow paths 71a to 74a connecting the ink supply ports 19 with through holes 71 to 74 forming reservoirs that communicate with the through holes 11a to 16a forming pressure generating chambers, and partition walls 75 to 75.
It is formed by 77. This makes it possible to evenly distribute the ink from the ink supply port 19 located on the line of symmetry of the nozzle opening row to each reservoir, and also to form the partition walls 75-
The strength of this space can be reinforced by using 77 as a structural member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head in which a pressure generating chamber is contracted by a piezoelectric vibrator and ink in the pressure generating chamber is ejected as an ink droplet from a nozzle opening.

[0002]

2. Description of the Related Art Ink jet recording heads can print efficiently at a very high resolution by reducing the size of the ink droplets because the dots on the recording medium are composed of ink droplets. Therefore, it is necessary to increase the number of nozzle openings, and when the piezoelectric vibrator is used as an ink droplet ejection source, miniaturization of the piezoelectric vibrator is a very important requirement. However, a certain amount of driving force is required to fly the ink droplets, and there is a limit to miniaturization of the piezoelectric vibrator. In order to improve the recording density under these restrictions, a plurality of rows of nozzle openings are provided, and the nozzle openings of each row are arranged in a space of another row in a so-called staggered arrangement. ing. By arranging the nozzle openings in a zigzag manner in this way, it is possible to improve the recording density up to about 90 dpi to 180 dpi. It is theoretically possible to further increase the recording density up to about 360 dpi by increasing the number of nozzle opening rows, but since the size of the ink jet recording head in the main scanning direction, that is, the paper width direction increases. However, there is a problem in that the positions of the dots formed by the nozzle opening rows arranged at both ends are noticeably misaligned. In order to solve such a problem, by arranging a dedicated reservoir for the pressure generating chamber row that communicates with the nozzle opening located at the outermost end, the distance between the nozzle opening rows at the outermost end can be minimized. An ink jet recording head in which the displacement of dots due to the inclination of the recording head has been reduced to a small size has also been proposed as seen in Japanese Patent Laid-Open No. 84919/1985.

[0003]

In the recording head having the above-described arrangement form, ink is supplied from the ink supply port to the connection point of each reservoir through independent supply conduits, so that the ink is supplied to each reservoir. Although it is easy to equalize ink distribution, there is a problem that the flow path structure becomes complicated. The present invention has been made in view of such a problem, and an object of the present invention is to prevent misalignment between dots to enable high-density printing, and to achieve an ink flow path from an ink supply port to a reservoir. It is an object of the present invention to provide a novel inkjet recording head having a simplified structure.

[0004]

In order to solve such a problem, in the present invention, a pressure generating element for generating a pressure in response to a print signal, a nozzle plate having a plurality of rows of nozzle openings, and the pressure A plate member that abuts the generating element, a pressure generating chamber row that communicates with the nozzle opening row, a reservoir, and a flow path that supplies ink to the reservoir from an ink supply port that is arranged on the line of symmetry of the nozzle opening row. When the number of nozzle opening rows is 2M (where M is an integer of 1 or more), the number N of the reservoirs is set to N = M + 1 and each of the reservoirs is connected to the ink supply port. A flow path separated by an extending partition wall communicates with the ink supply port.

[0005]

The distance between the nozzle opening rows located at the outermost ends can be made as small as possible, the distance change between the nozzle openings due to the tilt of the head can be made small, and ink is supplied to the reservoir. The flow passages can be formed as a common flow passage without reducing the strength of the region here.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments. FIG. 1 shows an embodiment of the present invention, in which reference numeral 1 is a nozzle plate having a predetermined pitch,
For example, the nozzle openings 2.2 and 2 are set to 180 DPI.
Nozzle opening rows with ... are arranged for 2M = 6 rows, 3,
4, 5, 6, 7, and 8 are formed.

Reference numeral 10 denotes a spacer, which is sandwiched between a vibrating plate 18 and a nozzle plate 1, which will be described later, and has a reservoir (not shown) corresponding to the nozzle row.
Through hole rows 11, 12, 13, 1 forming a pressure generating chamber
4, 15, 16, ... Are nozzle opening rows 3, 4, 5, 6, 7,
It is formed at a position corresponding to 8. In these nozzle opening rows 3 to 8, the nozzles in each row complement the nozzle openings in the other rows as shown in FIG. 2, and in this embodiment, the other nozzle opening rows are provided between the nozzle openings in one nozzle opening row 3. The nozzle openings 4 to 8 are arranged so as to be displaced from each other so as to form dots on the recording paper with a density as high as possible.

Reference numeral 18 denotes a vibrating plate which forms a pressure generating chamber facing the nozzle plate 1 through the spacer 10 and includes piezoelectric vibrator units 21, 22, 23, which will be described later.
The pressure generating chambers are contracted and expanded in response to expansion and contraction of the piezoelectric vibrators 30, 30, ...

These piezoelectric vibrator units 21, 22, 2
3, 24, 25, and 26, one half of the piezoelectric vibrators 30, 30, 30, ... Are fixed to the fixed substrate 31 at a fixed pitch, and the other half are vibrated in the longitudinal vibration mode. It is organized as possible. As shown in FIG. 4, each vibrator 30 is configured by alternately stacking the piezoelectric vibration material 32, the drive electrode 33, and the common electrode 34 in a sandwich shape. The drive electrodes 33, 33, 33, ... Are exposed from the end face on the rear end side of the piezoelectric vibrator 30, and are connected in parallel by a drive external electrode 35 formed by vapor deposition or the like, and the common electrodes 34, 34. , 34, ... Are exposed to the free end side of the piezoelectric vibrator 30 and are extended to the side, and the common external electrode 36 is provided.
Are connected in parallel by.

The drive external electrode 35 of each piezoelectric vibrator 30 is
The end surfaces are positioned so as to be substantially flush with the fixed substrate 31, and the common external electrodes 36 of the piezoelectric vibrators 30, 30, 30 ...
Dummy oscillators 39 located on both sides of 0, 30, 30 ...
It is connected to the electrode 40 on the rear end face so as to have a conductive relationship. The drive external electrode 3 is formed on the rear end surface of the dummy oscillator 39.
The electrode 40 is configured in the same manner as 5 and can be connected to the connection circuit board.

Returning to FIG. 1 again, reference numeral 50 in the drawing denotes a base, which is a vibrator unit 21, 22, 23, 24, 2 so that the free end sides of the piezoelectric vibrators 30, 30, 30, ... Are exposed.
Unit housing holes 51, 52, 53 for housing 5, 26,
54, 55, 56 and an ink supply port 57 for supplying the ink from the ink tank to the reservoir are provided, and the vibration plate 18, the spacer 10 and the nozzle plate 1 are positioned on the surface and also serve as an electrostatic shield. The recording head main body is fixed by the frame 58 and assembled together.

On the other hand, at the other end of the base 50, the drive external electrodes 3 of the piezoelectric vibrators 30, 30, 30, ... Exposed from the unit accommodating holes 51, 52, 53, 54, 55, 56.
5, 35, 35, ... And the electrode 40 of the dummy vibrator 39
The connection circuit board 60 connected to is fixed, and the board 61 used for fixing to the carriage is fixed therethrough.

FIG. 5 shows the ink flow passage of the present invention, that is, the arrangement structure of the reservoir and the pressure generating chamber, by means of through holes formed in the spacer 10. Reference numerals 11a, 11a in FIG.
11a ..., 12a, 12a, 12a ..., 13a, 1
3a, 13a ..., 14a, 14a, 14a ..., 15
a, 15a, 15a ..., 16a, 16a, 16a.
Through holes 13a and 13a, which are pressure generating chambers arranged in the central portion, are through holes which are formed corresponding to the nozzle opening rows 3, 4, 5, 6, 7, and 8, respectively. ,
13a ..., 14a, 14a, 14a ...
Through holes 13b, 13b, 13b, ..., 14 that communicate with the nozzle openings of the nozzle opening rows 5 and 6 on the opposite sides of 0.
b, 14b, 14b, ... Are arranged, and the other end side is a communication port 13 that communicates with through holes 71, 72 which will be reservoirs described later.
c, 13c, 13c ..., 14c, 14c, 14c.
Are formed.

Reference numerals 12 and 15 denote through hole arrays which are pressure generating chambers and are arranged symmetrically with respect to the line of symmetry 70, and the through holes 12a and 12 forming these through hole arrays.
, and 15a, 15a, 15a, ..., and 15a, 15a, 15a, 15a, 15a, 15a, 15a, 15a, ...
, b, 15b, ..., And on the side facing the line of symmetry, communication ports 12c, 12c, 12c, ... For supplying ink so as to communicate with the through holes 71, 72 serving as reservoirs.
And 15c, 15c, 15c ... Are formed.

Further, on the outermost end side, through holes 11b, 11b, 11b ... Which communicate with the nozzle opening rows 3 and 8 on the symmetry line 70 side.
, And 16b, 16b, 16b, ... Are arranged, and these are communication holes 11c, 11c, which serve as ink supply ports, on the outside.
11c ... And 16c, 16c, 16c ...
The holes 73 and 74, which are independent reservoirs, communicate with each other.

These reservoirs 71, 72, 73, 74
Are connected to the ink supply port 19 of the vibrating plate 18 through the flow paths 71a, 72a, 73a, and 74a, respectively, and the partition walls 75, 76, and 7 are formed so as to be symmetrical with respect to the symmetry line 70.
The inks are separated by 7, and the ink is configured to flow into each of the reservoirs evenly. As a result, it is possible to prevent a rapid expansion of the flow path, prevent pressure loss, and prevent bubbles from stagnating. Further, since the partition walls 75, 76, 77 are a kind of structural member near the ink supply port 19 which is a relatively wide space, this region can be reinforced.

FIG. 6 is an enlarged view of an embodiment of the partition wall in the vicinity of the ink supply port 19, and the partition wall 75,
In this embodiment, the reference numerals 76, 77 and 78 are formed into a "ten" shape so as to be integrated over the ink supply port 19 formed in the vibration plate 18. According to this embodiment, the ink from the ink supply port 19 can be more evenly distributed through the respective flow paths, and the bubbles that have entered from the ink tank can be dispersed and efficiently removed from the nozzle openings. Becomes Further, not only the rapid expansion of the flow path can be prevented to prevent the pressure loss and the stagnation of the air bubbles, but also the partition wall 75, 76, 77 can be reinforced more reliably.

FIG. 7 shows an embodiment of the manufacturing method of the above-mentioned spacer, in which the surface of the nozzle plate 1 on which the nozzle opening rows 2, 2, 2, ... A photosensitive resin film 8 having a thickness sufficient to secure the thickness of the pressure generating chamber and cured by exposure of one or more sheets.
Weld 0 (i). Then, the portions of the through holes 13a, 14a corresponding to the pressure generating chambers and the through holes 71, 72 corresponding to the reservoir are shielded from light, and the remaining portion is irradiated with reaction light through the exposure mask 83 having windows 81, 82 formed therein. (Ii). As a result, the areas 85, 86, 86 exposed to light are cured,
Further, the region 87 which has not been irradiated with light remains in an uncured state. By etching the uncured region, spacers having recesses 88, 88 only in the pressure generating chambers, and portions corresponding to the reservoir, the flow path, etc. are formed (iii).

FIG. 8 shows a process of manufacturing a single crystal silicon substrate having spacers as crystal axes (110) by anisotropic etching. Both surfaces are polished to form a thermal oxide film 90 on the surface of about 220 μm. A single crystal silicon substrate 91 having a crystal orientation (110) formed in a thickness of (1) is prepared (I), and a region where a through hole is to be formed by photolithography in accordance with a pattern to be formed on both sides or one side of the substrate. The silicon dioxide patterns 93, 93, ... Are formed corresponding to the portions other than 92, 92 ,.

Then, using these silicon dioxide film patterns 93, 93, ... As a mask, etching is performed with a potassium hydroxide solution (30 wt%) at 70 ° C. until a through hole is formed (III). As a result, the etching substantially progresses only in the thickness direction, and cavities 94, 94, 94 ... Having the crystal axis (111) as a wall surface are formed. After that, by removing the unnecessary silicon dioxide film, the through holes 95, 95, 95 which will be the pressure generating chamber and the reservoir are formed.
A spacer can be obtained by including (IV).

FIG. 9 shows an embodiment of a spacer formed by anisotropic etching of the above-mentioned single crystal silicon substrate. Like the embodiment shown in FIG. 5, the nozzle opening rows 3, 4, 5 are formed. , 6 ', 7', 8'through holes 11'a, 11'a, 11'a ..., 12'a, 1 '.
2'a, 12'a ..., 13'a, 13'a, 13'a
..., 14'a, 14'a, 14'a ..., 15'a,
15'a, 15'a ..., 16'a, 16'a, 16 '
a, through holes 11'c, which serve as communication ports for ink supply,
1'c, 11'c ..., 12'c, 12'c, 12'c
..., 13'c, 13'c, 13'c ..., 14'c,
14'c, 14'c ..., 15'c, 15'c, 15 '
c ... 16'c, 16'c, 16'c ..., Reservoir through holes 71 ', 72', 73 ', 74', flow paths 71'a, 72 'connecting the ink supply port and the reservoir. a, 73 '
Partition walls 76 'and 77' forming a and 74'a are formed correspondingly. In this embodiment as well, the partition walls 75 ', 76', 77 'which also form the flow path function as a kind of structural member while preventing the flow path from being suddenly expanded.

However, due to the use of anisotropic etching of the silicon single crystal substrate, as shown in FIG. 9B, the through hole 16c serving as a communicating hole for supplying ink is the through hole 16a serving as a pressure generating chamber. It is slightly different in that it is formed to be biased to one side.

FIG. 10 shows an ink jet recording head constructed by using each member formed as described above.
FIG. 3 is an enlarged cross-sectional view showing the vicinity of the third and fourth nozzle opening rows 5 and 6, in which a diaphragm 18 and a nozzle plate 1 are stacked with a spacer member 10 sandwiched between them.
It is integrally fixed by an adhesive or eutectic bonding so as to keep the person airtight. Then, in the region of the vibration plate 18 facing the pressure generating chamber, the free ends of the piezoelectric vibrators 30, 30, ... Of the piezoelectric vibrator unit are arranged in contact with each other.

In the ink jet recording head thus constructed, the reservoir is formed by the through holes 71 and 72 of the spacer 10, and the pressure generating chamber is formed by the through holes 13a and 14a. In this state, the piezoelectric vibrators 30, 30
When the vibrating plate 18 is pressed by, the volume of the pressure generating chamber is reduced and the ink supplied from the reservoir becomes ink droplets, and the nozzle openings 5 and 6 are ejected as ink droplets.
When the piezoelectric vibrators 30, 30 contract after the ink droplets are ejected, the pressure generating chambers expand, and the ink in the reservoir flows into the pressure generating chambers that have generated the ink droplets.

When the six nozzle opening rows thus constructed are formed on the same nozzle plate, the third and fourth pressure generating chambers located at the center are formed in the nozzle opening row 5. , A second row arranged outside the pressure generating chambers, with sides 13b and 14b communicating with 6 facing each other.
And the pressure generating chambers communicating with the nozzle opening rows 4 and 7 of the fifth row are arranged with the sides 12b and 15b communicating with the nozzle openings facing outward, and further, the nozzle opening rows of the first and sixth rows. The nozzle opening side of the pressure generating chamber communicating with 3 and 8 is 11
b and 16b are arranged toward the nozzle opening rows 4 and 7 located closest to them, and the through hole rows 11 and 16 are made to communicate with independent through holes 73 and 74, respectively. The distance L ₁ therebetween can be reduced.

That is, as shown in FIG. 5 (B), the reservoir 100 is formed in the central portion, and the through holes 101 and 10 are formed as the pressure generating chambers of the third and fourth rows so as to communicate with the reservoir 100.
1 and 102, 102, ..., and through-holes 103, which serve as pressure generating chambers in the second and fifth rows, are formed on the outside thereof.
And 104 are arranged so that the side communicating with the nozzle opening faces inward, and the through hole 10 serving as a reservoir is provided outside this.
5 and 106 are provided, and the through holes 107 and 108, which are pressure generating chambers, are arranged so as to communicate therewith,
It is possible to reduce the distance of the nozzle opening row by L ′ ₁ −L ₁ = ΔL _1, and it is possible to eliminate the positional deviation L × Cos θ of the dot due to the mounting error of the recording head on the carriage, especially the inclination θ with respect to the main scanning direction. The print quality can be improved by making the size as small as possible.

FIG. 11 shows a structure in the case where the number of nozzle opening rows is 2M = 4 by a spacer structure. Reference numerals 90 to 93 in the drawing denote first to fourth rows for forming pressure generating chamber rows. The first and second through hole rows 90 and 91 are opposed to each other at the sides 90a and 91a communicating with the nozzle openings, and the first and second through hole rows 90 and 91 are connected to the nozzle openings of the third and fourth through hole rows 92 and 93. The communicating sides 92a, 93a are opposed to each other, and a total of three reservoirs 94, 95, 96 are formed on the outermost end and the line of symmetry 70. Only the through hole rows 90, 93 are formed on the outermost end. Further, the through hole rows 91 and 92 are commonly connected to the reservoir 96. In addition, the ink supply port 19 and the reservoirs 94, 95 and 96 are symmetric with respect to the symmetry line 70.
They are separated by 7, 98 and connected.

In the case where two reservoirs 110 and 111 are provided and two rows of pressure generating chamber through holes 112, 113 and 114, 115 are communicated with each other by adopting the above arrangement structure of the pressure generating chambers. As compared with (FIG. 11B), the distance between the nozzle opening rows at the outermost end is reduced by ΔL ₂ = L ′ ₂ −L ₂ . In the ink jet recording head configured in this way, the distance between the nozzle opening rows becomes smaller than when the outermost nozzle opening row is arranged outward, so the main scanning direction and the reference line of the recording head Even if there is an inclination between the two, the dot deviation is reduced by ΔL × cos θ, and it is possible to prevent the print quality from deteriorating.

The ink supply port 1 is also the same as described above.
It is possible to more evenly distribute the ink from the nozzles 9 through the respective flow paths, and it is possible to disperse the bubbles that have entered from the ink tank and efficiently remove them from the nozzle openings. Not only can expansion be prevented to prevent pressure loss and stagnation of bubbles, but the region including the ink supply port 19 which is a relatively wide space can be reinforced by the partition walls 97 and 98.
In particular, when the number of nozzle opening rows is reduced to 4 rows, the number of partition walls is also reduced, so that the arrangement structure of FIG. 7A is used rather than the arrangement of FIG. If this is adopted, the number of partition walls increases and the ink supply ports 19 extend radially, so that the vicinity of the ink supply ports 19 can be reinforced more reliably.

In the above embodiment, the case where the nozzle opening rows are 4 rows and 6 rows has been described.
The same configuration can be applied to the case of 10 rows, 12 rows ... That is, when the nozzle opening row is 8 rows, the reservoirs are arranged so as to coincide with the symmetry line as shown in the second embodiment, and when the nozzle opening row is 10 rows, the reservoir is symmetric with the symmetry line. By arranging the reservoirs in each of the nozzles and arranging so that the pressure generating chambers in a single row communicate with the outermost reservoir in each case, the distance between the nozzle opening rows can be reduced.

[0031]

As described above, according to the present invention, a pressure generating element for generating a pressure in response to a print signal, a nozzle plate having a plurality of nozzle opening rows, and a plate member abutting the pressure generating element. , A pressure generating chamber row communicating with the nozzle opening row, a reservoir, and a spacer for partitioning the flow path for supplying ink to the reservoir from the ink supply port arranged on the symmetry line of the nozzle opening row, When the number of rows is 2M (where M is an integer of 1 or more), the number N of reservoirs is set to N = M + 1, and each reservoir communicates with the ink supply port by a flow path separated by a partition extending from the ink supply port. Therefore, the distance between the nozzle opening rows is reduced to reduce the dot positional deviation due to the tilt of the recording head, and the ink near the ink supply port is not reduced in strength. It is possible to simplify the ink flow path of each Rizabahe from the supply port.

[Brief description of drawings]

FIG. 1 is an exploded view showing an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement state of nozzle opening rows.

FIG. 3 is a perspective view showing an embodiment of a piezoelectric vibrator unit used in the same apparatus.

FIG. 4 is a diagram showing a cross-sectional structure of a piezoelectric vibrator that constitutes a piezoelectric vibrator unit.

5 (A) and 5 (B) are views showing an example of a spacer used in the same apparatus and an example of a case where the spacer is configured in another form.

FIG. 6 is an enlarged view showing an embodiment of the structure near the ink supply port of the spacer.

7A to 7I are views showing an embodiment of a method of manufacturing a spacer.

FIGS. 8 (I) to (IV) are diagrams showing an embodiment of a manufacturing method in the case of forming a spacer using a silicon single crystal substrate, respectively.

9 (A) and 9 (B) are enlarged views showing an example of a spacer formed of a silicon single crystal substrate and a through hole serving as a pressure generating chamber.

FIG. 10 is an enlarged cross-sectional view showing the vicinity of the pressure generating chamber according to an embodiment of the ink jet recording head using the same spacer.

11 (A) and (B) are views showing an optimal arrangement of pressure generating chambers and reservoirs and a conventional arrangement with a spacer structure in the case of four nozzle opening rows, respectively. is there.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nozzle opening 3-8 Nozzle opening row 10 Spacer 11-16 Through hole row 11a-16a which forms a pressure generation chamber 11a-16a Pressure generation chamber formation through hole 11b-16a Nozzle opening communication side 11c-16c Reservoir communication side 18 Vibration plate 19 Ink supply port 21-26 Piezoelectric vibrator unit 30 Piezoelectric vibrator 31 Substrate 57 Ink supply port 71-74 Reservoir through hole 75-77 Partition wall

Claims (6)

[Claims] 1. A pressure generating element for generating a pressure in response to a print signal, a nozzle plate having a plurality of nozzle opening rows, a plate member in contact with the pressure generating element, and a pressure generation communicating with the nozzle opening row. The nozzle array includes a chamber array, a reservoir, and a spacer for partitioning a flow path for supplying ink to the reservoir from an ink supply port arranged on the symmetry line of the nozzle opening array, and the number of the nozzle opening array is 2M (however, , M is an integer of 1 or more), the number N of the reservoirs is set to N = M + 1, and each of the reservoirs is an ink jet type that communicates with the ink supply port by a flow path separated by a partition extending from the ink supply port. Recording head. 2. The nozzle plate has six nozzle opening rows arranged in order from one end in the main scanning direction, and the first and sixth nozzle opening rows are provided in independent reservoirs, and the second and the second nozzle opening rows, respectively. The nozzle opening row of 3, and the fourth and fifth nozzle openings are in communication with a common reservoir.
Inkjet recording head. 3. The nozzle plate has four nozzle opening rows arranged in order from one end in the main scanning direction, and the first and fourth nozzle opening rows are independent reservoirs provided at the outermost ends, respectively. The ink jet recording head according to claim 1, wherein the second and third nozzle opening rows communicate with a common reservoir. 4. The ink jet recording head according to claim 1, wherein the spacer is formed of a photosensitive resin film by photolithography. 5. The ink jet recording head according to claim 1, wherein the spacer is formed by anisotropic etching of a silicon single crystal substrate having a crystal orientation (110). 6. The ink jet recording head according to claim 1, wherein the partition wall is formed so as to straddle the ink supply port.