JPH0499634A - Ink jet head - Google Patents

Abstract

PURPOSE:To miniaturize a device by providing a common ink chamber connected to ink flow paths which is filled with an ink absorber. CONSTITUTION:Ink becomes absorbed by an ink absorber 14 in a common ink chamber 13 after passing through a filter 16 from an ink supply orifice 15. If ink arrives in front of the ink absorber 14, each rear flow path 7 becomes filled rapidly with the ink by a capillary phenomenon as the rear end of a rear flow path 7 of each ink flow path 3 is set in contact with the front of the ink absorber 14 under a specified pressure. Thus a pressure chamber 6, a preflow path 5 and a nozzle 4 are filled with ink. A piezoelectric element 9 in each pressure chamber 6 is driven in accordance with a print signal to apply pressure to the ink in the pressure chamber 6. Although the pressure tends to propagate in an area where resistance becomes less, the pressure which has propagated to the rear reaches the ink absorber 14 in contact with the rear end of the rear flow path 7 after passing through the rear flow path 7. Then the pressure receives a high resistance to the propagation of the pressure, resulting in most of the ink not flowing to the rear and instead, flowing forward. Finally the ink is discharged from the nozzle part 4 to perform data printing.

Description

[Detailed description of the invention]

[Industrial Field of Application] This invention relates to an inkjet head. [Prior Art] Conventionally, the flow path configuration of an inkjet head is configured as shown in FIG. 5 (Japanese Patent Laid-Open No. 63-54250),
The ink flow path is formed by etching or the like on a substrate 1.1 made of glass or the like, and one flow path is connected to the nozzle 102. Front flow path 1
o3. Pressurized chamber 1o4° rear flow path 105. It is composed of a throttle section 106, and a plurality of flow paths are connected to a common ink chamber 107. [Problems to be Solved] By the way, when the common ink chamber 107 is pressurized by the pressurizing chamber 104, after the pressure wave propagates to the common ink chamber 107, crosstalk occurs, and the flow path of other non-driven channels. In order to prevent ink from being ejected from the nozzles, the design must be sufficiently wide, resulting in a large head and making it difficult to downsize the printer. Therefore, an object of the present invention is to provide an inkjet head that can be downsized. [Means for Solving the Problems] In order to achieve the second object, the present invention has a common ink chamber and a plurality of ink flow paths connected to the common ink chamber,
In an inkjet head that pressurizes ink using pressure chambers provided in each of a plurality of ink channels and ejects ink from a nozzle at the tip of each of the plurality of ink channels, a common ink chamber is filled with an ink absorber. be. [Operation] The pressure generated in the pressure chamber that travels backwards is propagated to the ink absorber filled in the common ink chamber.
The pressure that advances backward is rapidly weakened in the ink absorber section, and crosstalk is sufficiently prevented even if the common ink chamber is made small.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. First, a first embodiment will be explained. In FIG. 1.2, the inkjet head 1 has a first head portion consisting of a flow path substrate 2 and a diaphragm 8 attached to a front case 1.
After the case 1 is packaged with the ink absorber 14 and filled with the ink absorber 14,
2 is joined to the front case 11. Note that the rear case 12 and the front case 11 constitute a second head section. A plurality of ink channels 3 are formed on a channel substrate 2 made of a glass plate, a plastic plate, etc. by etching or the like.
Each ink flow path 3 has a nozzle portion 4. Front channel 5. Pressurized chamber 6. It has a rear flow path 7. Each nozzle 4 is densely arranged in a straight line, and each pressurizing chamber 6 requires a predetermined area.
The pressurizing chambers 6 are arranged in a fan-like manner with the nozzle portion at the center, and the positions of the pressurizing chambers 6 are changed in each ink flow path 3 in order to prevent the pressurizing chambers from spreading out. Therefore, since the length of the front flow path 5 is different for each ink flow path 3, in order to equalize the impedance of the ink flow path in the part before the pressurizing chamber 6, the short front flow path is formed thin or shallow, and the long front flow path is formed thin or shallow. The flow path is not thick or deep. Further, all of the rear flow passages 7 are opened to the linear rear end 2a of the flow passage substrate 2, and in order to equalize the impedance of each rear flow passage 7, the rear flow passage 7 is is bent to make it as long as possible. Further, in the flow path substrate 2 where the constriction portion is formed, the flow path impedance at the front portion of the pressurizing chamber 6 is considerably larger than the flow path impedance at the rear portion of the pressurizing chamber 6. A diaphragm 8 made of a glass plate or the like is covered on the upper surface of the channel substrate 2, and a piezoelectric element 9 is placed on the diaphragm 8 at the position of the pressurizing chamber 6.
is the installation. A front case 11 is attached to the flow path substrate 2 and the diaphragm 8 from the front with the nozzle portion 4 exposed, and is fitted to a rear case 12, which will be described later, at a rear position of the flow path substrate 2. The rear case 12 is joined to the front case 11 to form a common ink chamber 1.
A recessed portion is formed inside to form an ink absorber 14, and this recessed portion is filled with an ink absorber 14. The shape of the ink absorber 14 is substantially the same as that of the common ink chamber 13, but its volume is similar to that of the common ink chamber 13 so that it is compressed by a predetermined amount when the front case 11 and the rear case 12 are joined.
It is made larger than the volume of . The ink absorber 14 is made of a material such as a sponge made of sponge rubber or felt that can absorb ink and allow the ink to flow out, but has a predetermined resistance to the flow of ink inside the ink absorber. It is useful. The value of this resistance is set so that the flow path impedance at the rear of the pressurizing chamber 6 is larger than the flow path impedance at the front of the pressurizing chamber 6. Next, the rear case 12
An ink supply port 15 is formed on the rear wall at the same horizontal position as the nozzle portion 4, and a filter 16 is attached to a portion of the common ink chamber 13 that connects to the ink supply port 15. When assembling, fit the front case 11 onto the flow path board 2 and the diaphragm 8 from the front, and then fit the O-ring 17 to the rear of the flow path board 2 and the diaphragm 8 to prevent ink leakage. The rear case 12 is fitted over the O-ring 17 to the flow path substrate 2 and the diaphragm 8 from behind, and the contact surfaces of the front case 11 and the rear case 12 are bonded by adhesive, thermal welding, or the like. As a result, the ink absorber 14 is compressed by a predetermined amount, and its front surface is in pressure contact with the rear end of each of the rear channels 7 with a predetermined pressure contact force. The present embodiment is configured as described above, and the inkjet head 1 is placed on a carriage (not shown), and the ink supply port 15 is connected to an ink tank (not shown). When the ink in the ink tank is flowed to the inkjet head by priming, the ink passes through the ink supply port 15 and the filter 16 to the ink absorber 1 in the common ink chamber 13.
It is filled with 4. Then, the ink is absorbed into the ink absorber 14.
When reaching the front surface of the ink absorber 14, the rear end of the rear flow path 7 of each ink flow path 3 is in contact with the front surface of the ink absorber 14 under a predetermined pressure.
Ink is quickly filled into each rear flow path 7 due to capillary action, and the pressurized chamber 6. Front channel 5. The nozzle 4 is filled with ink. When briming is completed, the printing operation begins, and the piezoelectric elements 9 in each pressure chamber 6 are driven in accordance with the print signal to pressurize the ink in the pressure chamber 6. Then, the pressure tends to propagate in the direction with lower resistance, or the pressure propagated backward passes through the rear flow path 7 and reaches the ink absorber 14 that is in contact with the rear end of the rear flow path 7, where it The ink faces a large resistance to the propagation of pressure, so the ink cannot move backward much, but eventually moves forward and is ejected from the nozzle portion 4 to perform printing. Although the present embodiment does not have a constriction section, the ink absorber 14 plays the role of a constriction section, increases the impedance at the rear of the pressurizing chamber 6, and makes it possible to eject ink forward. At the same time, the pressure of the ink that has propagated to the ink absorber 14 hits the ink absorber 14 and is rapidly attenuated.
This sufficiently prevents the ink from being transmitted to other ink channels 3 and causing crosstalk. Note that the ink absorber 14 filled in the common ink chamber 13
plays the role of a large filter, and prevents dust, air bubbles, etc. flowing from the ink tank from flowing into the ink flow path 3. In this embodiment, the flow path substrate 2 includes a nozzle portion 4. Front channel 5, pressurization chamber 6. Since only the rear flow path 7 is formed by etching or the like, and the constriction part is eliminated, the yield in the etching process or the like can be improved. In other words, normally two-step etching is performed in which the shallow part is etched, then the part to be made shallow is masked, and only the deep part is etched. Therefore, if the shallow part is located between the nozzle part 102 and the aperture part 106, it is difficult to align the mask. However, if there is no constriction part, the positioning of the nozzle part 4 can be done easily, and the yield can be improved. In addition, the head is divided into a first head part and a second head part, and the common ink chamber 13 is located in the rear case 1 which is the second head part.
2, the common ink chamber 13 is eliminated from the etched portion, reducing manufacturing costs. Next, a second embodiment of the present invention will be described. In FIG. 3, the common ink chamber 23 is connected to the ink supply port 25.
As the distance increases, the length in the left and right direction increases. The ink absorber 14 has the same shape as the first embodiment (not shown). Therefore, when the front case 11 and the rear case 12 are joined and assembled, the central portion of the ink absorber 14 is compressed more than the peripheral portion. As a result, when the back flow path impedance of the ink flow path 3 in the peripheral part is larger than the back flow path impedance of the ink flow path 3 in the center part, the resistance in the ink absorber part is made smaller in the peripheral part than in the center part. The flow path impedance at the rear of the pressurizing chamber 6 can be made uniform. In this embodiment, the shape of the common ink chamber 23 was changed; however,
The shape of the common ink chamber 23 may remain the same as in the first embodiment, and the shape of the ink absorber may be made wider at the center. Next, a third embodiment will be explained. In FIG. 4, the front case 3 has a saw-shaped claw locking portion 31a formed on the outer circumference of the rear end, and the rear case 32 has a claw that engages with the claw locking portion 31a on the inner circumference of the front end. A portion 32a is formed. Note that a notch is provided in the portion where the claw portion 32a is formed. The present embodiment is constructed as described above, with the front case 31 fitting the channel substrate 2 and the diaphragm 8, and the ink absorber 14.
After filling the inner periphery of the case 32 with O-ring 17, fit it to the rear side surface of the flow path substrate 2 and the diaphragm 8, and further press the rear case 3 until the ink absorber 14 reaches the optimum compression amount.
2 is moved forward to lock the claw portion 32a in a predetermined position of the claw locking portion 31a, thereby changing the fitting depth of the second head member 31, 32 with respect to the first head member 2, 8. In this embodiment, it is possible to change the amount of compression, that is, the impedance, of the ink absorber 14 by changing the fitting depth of the second head part with respect to the first head part, and it is possible to change the amount of compression of the ink absorber 14, that is, the impedance. It is possible to eliminate manufacturing errors, variations, etc. between the first head section and the second head section. In this embodiment, the fitting depth adjustment mechanism is constructed of the pawl locking portion 31a and the pawl portion 32a, or may be configured in various other ways, such as by screwing. In the first to third embodiments of Section 2, the second head part may be constructed with a case divided into front and rear parts, or may be constructed with a case divided into side parts. The head may be constructed only by joining the road board 2 and the diaphragm 8 as a first head part, and the rear case as a second head part. In addition, in the first to third embodiments described above, the head is composed of a first head section and a second head section, and the common ink chamber is provided in the second head section, but the common ink chamber is arranged so that ink flows through the flow path substrate. It may be formed at the same time as the tract. [Effects] In the present invention, since the common ink chamber is filled with an ink absorber, crosstalk can be reduced, and the common ink chamber can therefore be made smaller, leading to the miniaturization of the head, that is, the miniaturization of head-equipped devices such as printers. It is possible to achieve this. Furthermore, since the common ink chamber is filled with an ink absorber, ink seepage from the nozzles is prevented when the posture of the head changes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the first embodiment, and FIG. 2 is a sectional view taken along line A-A in FIG.
Figure 3 is a cross-sectional view of the second embodiment.
FIG. 4 is a sectional view of the third embodiment, and FIG. 5 is a plan view of a conventional flow path substrate. 2.8 3 ・ 4 ・ 6 ・ 11. No. 2 13゜14・1a ・Inkjet head, ・・First head part, ・Ink channel, ・Nozzle, ・Pressure chamber, 12; 11, 22. 31. 32 ・ ・Part 1, 23・...Common ink chamber, -Ink absorber, 32a...Fitting depth adjustment mechanism. that's all

Claims (5)

[Claims] (1) It has a common ink chamber and a plurality of ink channels connected to the common ink chamber, and the ink is pressurized by a pressurizing chamber provided in each of the plurality of ink channels to create the plurality of ink channels. An inkjet head that ejects ink from nozzles at respective tips, wherein the common ink chamber is filled with an ink absorber. (2) The inkjet head according to claim 1, wherein the ink absorber is filled in the common ink chamber in a compressed state. (3) The inkjet head according to claim 2, wherein the ink absorber has a compression ratio that differs depending on the connection position of each of the plurality of ink channels. (4) In any one of claims 1 to 3, the first head portion has the plurality of ink channels formed therein, and the second head portion has the common ink chamber formed therein and is filled with the ink absorber. An ink-jet head characterized in that the first head part and the second head part are fitted and assembled together. (5) In claim 4, there is provided a fitting depth adjustment mechanism for varying the fitting depth between the first head part and the second head part, and the first head part and the second head part are connected to each other. Second
An inkjet head characterized in that the compression ratio of the ink absorber can be adjusted by changing the depth of engagement with the head portion.