JPH09226112A - Ink jet recording head - Google Patents

Abstract

(57) An object of the present invention is to provide an ink jet recording head in which the number of nozzles is increased without sacrificing the responsiveness of ink ejection and the printing speed is dramatically improved. A nozzle plate (2) having a plurality of nozzle openings (1) is communicated with a plurality of pressure chambers (4) arranged so as to separate partition walls from each other, and at least one end of each pressure chamber (4) is arranged so as to separate partition walls. The flow path forming plate 3 having the common ink chamber 6 for communicating ink to each of the ink supply units 5 connected to each other and the piezoelectric vibrator 10 are bonded to each other to apply pressure to each pressure chamber 4. In an ink jet recording head in which elastic plates 8 that cause a change are laminated, as a path for supplying ink to the common ink chamber 6, the ink introduction port of the elastic plate 8 and the ink are provided at a position facing the ink supply unit 5. An ink supply tube 12 for supplying the ink is arranged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inkjet recording apparatus for recording an image or a character on a recording medium by ejecting ink droplets from a nozzle opening. More specifically, the inkjet recording head has multiple nozzles. The present invention relates to an ink flow path structure.

[0002]

2. Description of the Related Art Conventionally, ink jet recording heads are
As proposed in Japanese Unexamined Patent Publication No. 7-323543, a nozzle plate having nozzles, a pressure chamber, a common ink chamber, a flow path forming plate in which ink flow paths are formed, and an elastic plate are laminated, The plate is arranged so that it can be pressed by the piezoelectric vibrator. A case containing a piezoelectric vibrator unit is joined to the elastic plate. The case is provided with an ink supply tube. By joining the case and the elastic plate, the ink supply tube provided in the case and the hole for ink supply provided in the elastic plate are brought into contact with each other to supply the ink to the common ink chamber (reservoir in the publication). In order to secure the rigidity of the flow path forming plate (spacer in the publication), the common ink chamber has a connection partition wall that connects the central body portion and the partition wall that partitions the common ink chamber.

[0003]

However, in the structure of the above-mentioned Japanese Patent Laid-Open No. 7-323543,
When the number of nozzles is increased in order to improve the printing speed of the inkjet recording head, the length of the common ink chamber is increased by the number of nozzles. As the length of the common ink chamber increases, the flow path loss in the common ink chamber increases. Therefore, when an ink is supplied from one end to the other end of the nozzle array with one ink supply pipe as in the above-mentioned publication, a pressure gradient is generated in the common ink chamber. Due to this, the responsiveness of ink ejection is lowered as the nozzle is farther from the ink supply tube, and when the recording head is driven at a high frequency, the ink ejection characteristic becomes unstable, and as a result, the printing speed must be reduced.

The width of the common ink chamber should be increased,
The head becomes larger. When a large number of ink jet recording heads are used to form a color ink jet recording head, the recording heads are arranged side by side, and the reciprocating distance in the scanning direction becomes long, which hinders high-speed printing. Further, since the distance between the recording heads increases and the nozzle row interval increases, the accuracy of the landing position of the ejected ink deteriorates and the print quality deteriorates.

Therefore, the present invention solves the above-mentioned problems, and an object of the present invention is to increase the number of nozzles without sacrificing the responsiveness of ink ejection, thereby dramatically improving the printing speed. The present invention provides the ink jet recording head.

[0006]

A nozzle plate having a plurality of nozzle openings, a plurality of pressure chambers communicating with each of the nozzle plates and arranged with a pressure chamber partition wall, and at least one end of each pressure chamber is A piezoelectric vibrator is bonded to a flow path forming plate having a common ink chamber for supplying ink to each of the ink supply units through the ink supply units arranged in communication with each pressure chamber and separated from each other by the supply unit partition wall. In an ink jet recording head in which elastic plates that cause a pressure change in each of the pressure chambers are stacked, the elastic plate is provided at a position facing the ink supply unit as a path for supplying ink to the common ink chamber. It is characterized in that an ink introduction port and an ink supply pipe for supplying ink are arranged.

Further, the flow path forming plate connects at least one of the supply part partition wall and the outer peripheral wall of the common ink chamber,
It is characterized by having a separation wall that divides two common ink chambers.

Further, the supply part partition wall is wider than the pressure chamber partition wall, and the separation wall width is narrower than the supply part partition wall width at least in the vicinity of the connection with the supply part partition wall.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a first embodiment of the present invention and is an exploded perspective view of the overall construction of an ink jet recording head. FIG. 2 is an enlarged view of the separation wall of the common ink chamber of the flow path forming plate shown in FIG.

This embodiment will be described with reference to FIGS. 1 and 2. A nozzle plate 2 has a plurality of nozzle openings 1 formed therein. Reference numeral 3 denotes a flow path forming plate, in which a pressure chamber 4 communicating with each nozzle opening 1, an ink supply unit 5, and a common ink chamber 6 for supplying ink to each ink supply unit 5 are formed. Reference numeral 7 is a separation wall for separating the common ink chamber. 8 is an elastic plate. The elastic plate 8, the nozzle plate 2, and the flow path forming plate 3 are laminated and adhered to form an ink flow path unit 100.
Reference numeral 9 denotes a case for fixing the ink flow path unit 100, which is formed by injection molding of epoxy resin in this embodiment. Since the ink supply pipe 12 provided in the case 9 is connected across the separation wall 7, the ink can be supplied to each of the two divided common ink chambers 6. The PZT 10 is a piezoelectric vibrator having a longitudinal vibration mode, and is configured to generate a large displacement at a low applied voltage by being a laminated type. One end of the PZT 10 is adhered to the mounting plate 11 and joined to the case 9 via the mounting plate 11. The other end of the PZT 10 is joined to the elastic plate 8. In the present embodiment, the ink jet recording head having such a structure has the elastic plate 8 formed by expansion and contraction of the PZT 10.
Is deformed to give a pressure change to the pressure chamber 4, and the nozzle opening 1
Recording is performed on the recording medium by ejecting more ink.

In this embodiment, the flow path forming plate 3 is made of a silicon single crystal having a thickness of 280 μm. The pressure chamber 4, the ink supply unit 5, the common ink chamber 6, and the separation wall 7 are formed by etching with KOH from both surfaces of the nozzle plate and the elastic plate. Separation wall 7 in common ink chamber 6
Are formed.

Here, the etching of the flow path forming plate 3 will be described. The silicon single crystal of the flow path forming plate 3 has the crystal orientation (110) plane as the joint surface of the elastic plate 8 and the nozzle plate 2, and the flow path forming plate 3 along the crystal orientation (211) direction of the surface on the nozzle plate 2 side. A pattern corrected to have the shape of 3 is formed. As the protective film, silicon dioxide obtained by oxidizing the silicon surface is used. KOH at 80 ℃ in this state
When the etching is performed with a 20% aqueous solution, the crystal orientation (111) plane of the silicon single crystal plate appears neatly, and this plane forms the pressure chamber 4, the ink supply unit 5, the common ink chamber 6, and the separation wall 7. As described above, the flow path forming plate 3 is manufactured by using the method of anisotropic etching of silicon, so that the pitch of the nozzle openings is 14 when the plate thickness is 150 μm or more.
It is possible to easily realize a high density of 0 μm or less.

Next, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

The present invention differs from the first embodiment in that the number of nozzle openings 1 is 132 in one row and the pitch thereof is 1 /.
It is 180 inches. At this time, the common ink chamber 6
Has a length of 132 × (1/180) inches. If the ink supply pipe 12 is arranged at one end of the row of the nozzle openings 1 (see FIG. 4), the ink ejected from the nozzle opening farthest from the ink supply pipe 12 due to the flow path loss in the common ink chamber 6. Is different from the amount of ink ejected from the nozzle opening closest to the ink supply pipe 12.

The graph in FIG. 5 shows the experimental results. Depending on the distance between the nozzle opening farthest from the ink supply tube 12 and the nozzle opening closest to the ink supply tube 12, the ink supply tube 12
Compared to the amount of ink ejected from the nozzle opening near
A difference of 20% or more occurs. Therefore, the ink supply pipe 12
Must be installed at a location where the distance from the ink supply pipe 12 to the ink supply section 5 is the shortest. However,
Unless the distance is suppressed to about 1/2 inch, it is 5 kHz.
At the ink ejection frequency of z, the amount of ink ejected from the nozzle opening farthest from the vicinity of the supply pipe is different by 10% or more.

For this reason, in this embodiment, one separation wall 7 is provided in the common ink chamber 6 and the ink supply pipe 12 is connected to the position 12b in FIG. The separation wall 7 serves as one of the adhesive supports of the case 9 and the elastic plate 8, and in particular, the ink supply pipe 12 and the ink supply hole 8b opened in the elastic plate 8 can be reliably joined to each other, and No worries about leaks. Further, by separating the ink supply chamber 6,
As shown in, it is possible to suppress variations in the speed and weight of the ink ejected from the upper and lower nozzle openings in the figure with the ink supply tube interposed therebetween. This is because even if the number of upper and lower ink ejections is uneven, the deviation of the ink flow rate can be suppressed by the separation wall 7.

Next, the shape of the connecting portion between the separating wall 7 and the ink supply portion 5 will be described with reference to FIG.

In the embodiment of the present invention, the nozzle pitch is 1
/ 180 inches and the width of the partition wall 4b of the pressure chamber 4 is 0.0
41 mm (not shown), and the width of the partition wall 5b of the supply port 5 is 0.
The width of the separating wall 7 is 0.05 mm and the width of the separating wall 7 is 0.05 mm.

Further, the property of anisotropic etching of the silicon single crystal plate is positively used, and the supply port 5n adjacent to the separation wall 7 is used.
From the end of the ink introduction port to the separation wall 7 at angles θ1 and θ2
By connecting the inks at about 30 degrees, the discharge performance of the bubbles that have entered the common ink chamber 6 is improved, and the ink ejection characteristics are constant from all the nozzles without changing the inertance of the supply port 5n adjacent to the separation wall 7. Can be obtained.

Next, a third embodiment of the present invention will be described.

The difference of the present invention from the first embodiment is that FIG.
, The number of nozzle openings 1 is increased to 260 per row with a pitch of 1/180 inch, and the common ink chamber 6 has 260
This is a point having a length of × (1/180) inch. In this case, two separation walls 7 are provided in the common ink chamber 6, and the ink supply pipe is connected to the portion a shown in FIG.

Next, a fourth embodiment of the present invention will be described.

FIG. 8 is an enlarged view of the vicinity of the separation wall 17 of the fourth embodiment. The present embodiment is different from the second embodiment in that the shape of connecting the separation wall 17 to the common ink chamber outer peripheral wall is stepped. With such a shape, it is possible to further improve the performance of discharging bubbles that have entered the inside of the common ink chamber 6 while maintaining the function of adhering and supporting the case 9 and the elastic plate 8.

Next, a fifth embodiment of the present invention will be described.

FIG. 9 is an enlarged view of the vicinity of the separation wall 27 of the fifth embodiment. The difference of this embodiment from the first embodiment is that the through hole 13 is provided in the separation wall 27.

The elastic plate 8 is divided by the separating wall 27. Therefore, the compliance of the elastic plate 8 is locally reduced near the separation wall 27. The lack of compliance in the common ink chamber 6 contributes as fluid crosstalk between adjacent pressure chambers. Further, if the compliance is locally insufficient, the ink ejection characteristics will be non-uniform.

Therefore, the through hole 13 is provided in the separating wall 27,
By increasing the compliance, it is possible to compensate for the lack of compliance of the elastic plate 8 near the separation wall 27.

FIG. 10 is a top view of the ink jet recording head of the sixth embodiment.

This embodiment is different from the other embodiments in that the common ink chambers 61, 62, 63, 6 divided by the separating wall 37 are used.
4 is to supply ink of different colors to each other to form a color ink jet recording head. According to this embodiment, different colors can be continuously ejected from the nozzle openings, color printing can be performed only by a line feed operation, and high speed printing can be performed. In addition,
In the present embodiment, ink is supplied from the portion a in FIG. 10, but when the length of the common ink chamber becomes long, as shown in the first, second, and third embodiments, the ink is crossed over the partition walls. Ink is supplied in a structure in which the ink supply unit a is arranged.

[0031]

The ink supply pipe 12 is arranged in the middle of the ink supply section 5 to realize a high responsiveness of ink ejection without enlarging the outer shape of the ink jet recording head having a large number of nozzles and to improve the printing speed. It is possible to provide a dramatically improved multi-nozzle inkjet recording head.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of the overall configuration of an inkjet recording head according to an embodiment of the present invention.

FIG. 2 is an enlarged view of the separation wall of the common ink chamber of the flow path forming plate of the ink jet recording head according to the embodiment of the present invention.

FIG. 3 is a top view of an ink jet recording head according to a second embodiment of the invention.

FIG. 4 is a comparative example of a top view of an ink jet recording head according to a second embodiment of the invention.

FIG. 5 is a diagram illustrating a relationship between a distance between a nozzle near an ink supply tube and a farthest nozzle and an ink weight according to the second embodiment of the present invention.

FIG. 6 is an enlarged view of a separation wall of the common ink chamber of the flow path forming plate of the ink jet recording head according to the second embodiment of the present invention.

FIG. 7 is a top view of an ink jet recording head according to a third embodiment of the invention.

FIG. 8 is an enlarged view of the separation wall of the common ink chamber of the flow path forming plate of the ink jet recording head according to the fourth embodiment of the present invention.

FIG. 9 is an enlarged view of the separation wall of the common ink chamber of the flow path forming plate of the ink jet recording head according to the fifth embodiment of the present invention.

FIG. 10 is a top view of a flow path forming plate of an ink jet recording head according to a sixth embodiment of the present invention.

[Explanation of symbols]

 1 Nozzle Opening 2 Nozzle Plate 3 Flow Forming Substrate 4 Pressure Chamber 5 Ink Supply Section 6 Common Ink Chamber 7 Separation Wall 8 Elastic Plate 9 Case 11 Mounting Plate 10 Piezoelectric Vibrator 12 Ink Supply Pipe

Claims (9)

[Claims] 1. A nozzle plate having a plurality of nozzle openings, a plurality of pressure chambers communicating with the nozzle openings and arranged in a row with a pressure chamber partition wall therebetween, and at least one end of each pressure chamber. A flow path forming plate formed by connecting ink supply parts, which are in communication and arranged in a row with a partition wall in communication, to a common ink chamber, and an elastic plate that joins a piezoelectric vibrator to cause a pressure change in each pressure chamber. In an ink jet recording head formed by stacking each of the above, as an ink supply path to the common ink chamber, an ink supply port for supplying ink and an ink introduction port of the elastic plate at a position facing the ink supply section. An ink jet recording head characterized by having and. 2. The flow path forming plate has at least one or more separating walls that connect the supply partition wall and the outer peripheral wall of the common ink chamber and divide the common ink chamber. 1. The inkjet recording head according to 1. 3. The width of the supply partition wall is wider than that of the pressure chamber partition wall, and the width of the separation wall is narrower than the width of the supply partition wall at least near the connection with the supply partition wall. The ink jet recording head according to claim 1, wherein 4. The ink jet recording head according to claim 1, wherein the flow path forming plate is a silicon substrate. 5. The ink jet recording head according to claim 1, wherein the piezoelectric vibrator is a laminated piezoelectric vibrator having a longitudinal vibration mode. 6. The outer peripheral wall of the common ink chamber, the supply part partition wall, and the separation wall are rigidly fixed to the case via the elastic plate, and the elastic plate corresponding to the common ink chamber has a space in the case. The ink jet recording head according to claim 1, wherein the ink jet recording head is not fixed. 7. The ink jet recording head according to claim 1, wherein the separation wall has a through groove in a direction in which the nozzle plate, the flow path forming plate and the elastic plate are stacked. . 8. The ink jet recording head according to claim 1, wherein an ink supply pipe provided in the case is connected across the separation wall. 9. The ink jet recording head according to claim 1, wherein the common ink chamber divided by the separation wall is filled with ink of different colors.