JP6914677B2 - Liquid discharge head - Google Patents

Description

The present invention relates to a liquid ejection head that ejects a liquid such as ink.

Conventionally, as an image forming apparatus for forming an image on a recording medium such as paper, an image forming apparatus such as a thermal transfer method, a wire dot method, a heat sensitive method, and an inkjet method has been put into practical use. Among them, the inkjet method is attracting attention as a recording method that has a low running cost and suppresses recording sound, and is used in a wide range of fields. In an inkjet image forming apparatus, by driving an energy generating element, droplets are ejected from the ejection port of an ejection port forming member formed on a substrate, and the droplets are landed at a desired position on a recording medium. The image is formed by.

A large number of discharge ports are arranged in the discharge port forming member with high density and high accuracy. Therefore, the discharge port forming member is formed by laminating a photosensitive organic resin material on a substrate, exposing it with an exposure machine such as a stepper, and developing it. The discharge port forming member manufactured by such a manufacturing process may be deformed due to curing shrinkage during the manufacturing process. Even in the user's usage environment, the discharge port forming member and the substrate may be deformed due to the heat applied to the discharge port forming member due to the driving of the energy generating element and the swelling of the discharge port forming member due to the liquid filled inside. be. When the discharge port forming member or the substrate is deformed, a shearing force parallel to the joint surface or a tensile force in the direction perpendicular to the joint surface is applied to the joint surface between the discharge port forming member and the substrate which are in close contact with each other. The discharge port forming member may peel off from the substrate.

Patent Document 1 discloses a liquid discharge head in which one slit facing the liquid supply port is formed in the discharge port forming member formed on the substrate in order to prevent the discharge port forming member from peeling off from the substrate. Has been done. Since the deformation of the discharge port forming member is absorbed by the slit, the deformation of the discharge port forming member at the joint surface between the discharge port forming member and the substrate is suppressed, and the discharge port forming member is less likely to peel off from the substrate.

Japanese Unexamined Patent Publication No. 2012-51235

The peeling of the discharge port forming member from the substrate is suppressed to some extent by the slit described in Patent Document 1, but when the discharge port forming member made of resin is cured and shrunk during the manufacturing process, the stress due to deformation may be concentrated in the slit. There is. In this case, cracks may occur in the vicinity of the slit. Further, in recent years, the liquid discharge head may be made longer to speed up printing, or the distance from the end of the substrate to the discharge port row of the discharge port forming member may be reduced to reduce the cost. be. Since such a liquid discharge head has a reduced rigidity of the substrate and is easily deformed, there is a possibility that the slit described in Patent Document 1 cannot sufficiently suppress the peeling of the discharge port forming member from the substrate.
An object of the present invention is to provide a liquid discharge head in which cracks in the discharge port forming member and peeling of the discharge port forming member from the substrate are unlikely to occur.

The liquid discharge head of the present invention has a substrate and a discharge port forming member located on the substrate and formed of a photosensitive resin. The discharge port forming member includes a plurality of discharge ports arranged in the first direction to discharge the liquid, and forms a plurality of pressure chambers communicating with the plurality of discharge ports with the substrate. The substrate has a liquid supply port that is located on a surface facing the discharge port forming member, extends in the first direction, and communicates with a plurality of pressure chambers. The discharge port forming member has two slits extending in a first direction on a surface facing the liquid supply port. The two slits are provided line-symmetrically with respect to the center line extending in the first direction of the liquid supply port. The thickness of the discharge port forming member between the two slits is equal to the thickness of the discharge port forming member at the end of the discharge port forming member in the second direction orthogonal to the first direction. The liquid discharge head further includes a beam extending in the first direction to form a side wall of the slit, a first filter located in front of some pressure chambers and separated from the beam, and the front of the other pressure chamber from the beam. It has a beam-shaped second filter that extends to.

According to the present invention, the discharge port forming member has a plurality of slits facing the liquid supply port and extending in the first direction. As a result, the deformation of the discharge port forming member is absorbed by the plurality of slits, the deformation of the entire discharge port forming member is suppressed, and the peeling of the discharge port forming member from the substrate is suppressed. Further, by forming the plurality of slits, the stress applied to the slits at the time of curing and shrinking of the discharge port forming member can be dispersed, and the occurrence of cracks in the discharge port forming member can be suppressed. Therefore, according to the present invention, it is possible to provide a liquid discharge head in which cracks in the discharge port forming member and peeling of the discharge port forming member from the substrate are unlikely to occur.

It is a perspective view of the liquid discharge head which concerns on 1st Embodiment of this invention. It is a top view of the recording element substrate of the liquid discharge head shown in FIG. 2 is a partially enlarged plan view and a cross-sectional view of the recording element substrate shown in FIG. 2. It is a top view and the cross-sectional view of the recording element substrate of the liquid discharge head of the comparative example 1. FIG. 2 is a plan view and a cross-sectional view of a recording element substrate of the liquid discharge head of Comparative Example 2. It is a partially enlarged plan view and sectional view of the recording element substrate of the 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The liquid ejection head described below relates to an inkjet head mounted on an inkjet printer and ejecting ink, but the liquid ejection head of the present invention can also be applied to applications other than ink ejection.

(First Embodiment)
FIG. 1 is a perspective view showing a liquid discharge head 1 according to the first embodiment of the present invention. FIG. 2 is a top view of the recording element substrate 2 of the liquid discharge head 1 shown in FIG. 1, and for convenience, the liquid supply port 13 inside the recording element substrate 2 is also shown. The liquid ejection head 1 is mounted on a carriage (not shown) of a printer body (not shown), ejects ink to the recording medium while being scanned in the width direction of the recording medium, and forms an image on the recording medium. Ink is supplied from an ink tank (not shown) mounted on the printer body to a sub tank (not shown) of the liquid ejection head 1 via a supply path inside the printer body, and is a recording element through an internal ink flow path. It is supplied to the substrate 2. The power supply voltage and the drive signal for ejecting ink are supplied from the printer main body to the recording element substrate 2 via the contact substrate 3 of the liquid ejection head 1, the electrical wiring member 4, and the pad 5 of the recording element substrate 2.

3 (a) is an enlarged view of part A of FIG. 2, and FIG. 3 (b) is a cross-sectional view taken along the line AA of FIG. 3 (a). The recording element substrate 2 of the liquid discharge head 1 includes a substrate 6 and a discharge port forming member 7 formed on the substrate 6 and made of a resin material.
The discharge port forming member 7 includes a plurality of discharge port rows 9 including a plurality of discharge ports 8 for ejecting ink (see FIG. 2). The discharge port rows 9 extend parallel to each other, and the plurality of discharge ports 8 of each discharge port row 9 are arranged in the first direction X. The discharge port forming member 7 has a plurality of recesses facing the substrate 6, and the plurality of recesses form a plurality of pressure chambers 10 with the substrate 6. The discharge port forming member 7 is formed by laminating a photosensitive organic resin material on a substrate 6, exposing it with an exposure machine such as a stepper, and developing it.

The substrate 6 includes a plurality of energy generating elements 11 arranged in the first direction X and giving energy for ejection to the ink. The energy generating element 11 of the present embodiment is a heat generation resistance element, but may be a piezoelectric element. One discharge port 8 and one energy generating element 11 correspond to one pressure chamber 10. The substrate 6 has a liquid supply path 12 that penetrates the substrate 6 in the thickness direction. The opening of the liquid supply path 12 facing the discharge port forming member 7 extends in the first direction X and serves as a liquid supply port 13 that communicates with the plurality of pressure chambers 10. That is, the substrate 6 has a liquid supply port 13 that is located on a surface facing the discharge port forming member 7, extends in the first direction X, and communicates with a plurality of pressure chambers 10. As shown in FIG. 2, two liquid supply ports 13 are provided, and one row of discharge port rows 9 is arranged on both sides of each liquid supply port 13.

The portion of the discharge port forming member 7 facing the liquid supply port 13 (hereinafter, referred to as the supply port facing portion 14) has two slits 15a and 15b extending in the first direction X. First to third beams 16a to 16c extending in the first direction X are formed in a portion of the discharge port forming member 7 facing the liquid supply port 13. A first slit 15a is formed between the first beam 16a and the second beam 16b. A second slit 15b is formed between the second beam 16b and the third beam 16c. The first to third beams 16a to 16c form the side walls of the slits 15a and 15b. In other words, the supply port facing portion 14 of the discharge port forming member 7 has a central beam portion 17, and the central beam portion 17 is provided with two slits 15a and 15b. In one example, the width a of the central beam portion 17, that is, the distance a between the outer side surface of the first beam 16a and the outer side surface of the third beam 16c is 82 μm, and the first slit 15a and the second slit The width b of 15b is 15 μm. Although the number of slits is not limited, three or more slits may be formed as long as the rigidity of the entire discharge port forming member 7 is not excessively lowered and the discharge port forming member 7 is easily peeled off from the substrate 6. In the present embodiment, a total of two slits are provided, one at a position symmetrical with respect to the center line 13A extending in the first direction X of the liquid supply port 13. As a result, the rigidity of the supply port facing portion 14 becomes equal on both sides with respect to the central axis 13A of the liquid supply port 13, and a portion having extremely large deformation does not occur. When an even number of slits are provided, it is preferable to arrange them symmetrically with respect to the center line 13A of the liquid supply port 13. When an odd number of slits are provided, one slit is arranged at the center line 13A of the liquid supply port 13 so that the center line of the slit coincides with the center line 13A of the liquid supply port 13, and the remaining slits are provided. It is preferable to arrange the liquid supply port 13 symmetrically with respect to the center line 13A.

Further, the discharge port forming member 7 has a first filter 18a and a second filter 18b alternately arranged in the first direction X. The first filter 18a is a columnar structure located between the liquid supply port 13 and a part of the pressure chamber 10. The second filter 18b is a beam-like structure extending from the first and third beams 16a and 16c facing the pressure chamber 10 to the front surface of the other pressure chamber 10. Both the first filter 18a and the second filter 18b are located in front of the pressure chamber 10 to prevent foreign matter such as dust from flowing into the pressure chamber 10. The distance from the pressure chamber 10 to the first filter 18a and the second filter 18b is the same. The first filter 18a is connected only to the ceiling portion 19 of the discharge port forming member 7, and is independent or separated from the first and third beams 16a and 16c. On the other hand, the first filter 18a is not only connected to the ceiling portion 19 of the discharge port forming member 7, but also integrated with the first beam 16a or the third beam 16c. Therefore, the rigidity of the entire discharge port forming member 7 is increased, and the discharge port forming member 7 is less likely to be peeled from the substrate 6.

The ink is supplied from the opening 20 on the side opposite to the liquid supply port 13 of the liquid supply path 12, and is supplied to the pressure chamber 10 through the liquid supply port 13 of the liquid supply path 12. By driving the energy generating element 11 in the pressure chamber 10, bubbles are formed in the pressure chamber 10. The ink in the pressure chamber 10 is ejected from the ejection port 8 by air bubbles and lands on the recording medium to form an image.

The substrate 6 and the discharge port forming member 7 may be deformed due to the heat generated by driving the energy generating element 11 or the swelling of the discharge port forming member 7. At that time, if a tensile stress or a shear stress equal to or higher than a certain threshold is applied to the joint surface between the substrate 6 and the discharge port forming member 7, the discharge port forming member 7 that has been in close contact with the substrate 6 may be peeled off from the substrate 6. be. When the discharge port forming member 7 is peeled off, in the worst case, ink is not supplied to the pressure chamber 10, and ejection failure may occur and the quality of the recorded image may be deteriorated.

FIG. 4 shows a diagram similar to that of FIG. 3 of the liquid discharge head 1 of Comparative Example 1. In order to prevent the discharge port forming member 7 from peeling from the substrate 6, one slit 115 extending in the first direction X is formed at a portion of the discharge port forming member 7 facing the liquid supply port 13. By letting the deformation of the discharge port forming member 7 escape to the slit 115, the deformation of the discharge port forming member 7 at the joint surface with the substrate 6 is suppressed, and the peeling of the discharge port forming member 7 from the substrate 6 is suppressed. However, in Comparative Example 1, when the discharge port forming member 7 is cured and contracted in the manufacturing process, the stress generated by the deformation is concentrated on the thin portion of the ceiling portion 19 of the discharge port forming member 7 whose wall thickness is reduced by the slit 115. Cracks may occur. In particular, this phenomenon is likely to occur when the deformation of the recording element substrate 2 becomes larger, such as the lengthened liquid discharge head 1.

FIG. 5 shows a diagram similar to that of FIG. 3 of the liquid discharge head 1 of Comparative Example 2. In Comparative Example 2, the width of the slit 215 is expanded as compared with Comparative Example 1. Therefore, the stress is dispersed and relaxed in the slit 215, and cracks in the discharge port forming member 7 are unlikely to occur. However, since the thin portion of the discharge port forming member 7 is enlarged, the rigidity of the discharge port forming member 7 is reduced, and the amount of deformation when stress is applied is increased. That is, in the user's usage environment, when heat generated by driving the energy generating element 11 or swelling of the discharge port forming member 7 occurs, the discharge port forming member 7 is likely to be greatly deformed. As a result, the discharge port forming member 7 may be more easily peeled from the substrate 6 than in Comparative Example 1.

On the other hand, in the embodiment shown in FIG. 3, two slits having the same width as that of Comparative Example 1 are provided in the supply port facing portion 14. By providing the two slits, the stress concentrated on the thin portion of the ceiling portion 19 of the discharge port forming member 7 is dispersed when the discharge port forming member 7 is cured and contracted. As a result, cracks are less likely to occur in the thin portion of the ceiling portion 19 of the discharge port forming member 7 as compared with Comparative Example 1. Since the portion of the supply port facing portion 14 other than the thin portion is maintained at the same thickness as in Comparative Examples 1 and 2 and the plurality of slits 15 are dispersedly arranged, the decrease in rigidity of the discharge port forming member 7 is suppressed. NS. Therefore, peeling of the discharge port forming member 7 from the substrate 6 is unlikely to occur.

As described above, in the liquid discharge head of the present embodiment, cracks that are easily manifested in a recording element substrate that is more easily deformed, such as a long recording element substrate, and peeling of the discharge port forming member 7 from the substrate 6 are formed. It can be suppressed only by changing the configuration of the member 7. Therefore, according to the present embodiment, the reliability of the liquid discharge head can be improved while suppressing the influence on the cost.

(Second Embodiment)
FIG. 6 shows a diagram similar to that of FIG. 3 of the liquid discharge head 1 according to the second embodiment. Here, only the points different from the first embodiment will be described. In the present embodiment, all the filters are composed of the columnar first filter 18a described above, and the second filter 18b is not provided. Also in this embodiment, two slits 15a and 15b having the same width as those in the first embodiment are provided in the supply port facing portion 14 of the discharge port forming member 7. In the present embodiment as well, as in the first embodiment, cracks and peeling of the discharge port forming member 7 from the substrate 6 can be suppressed, and the reliability of the liquid discharge head 1 is improved while preventing an influence on the cost. be able to.

1 Liquid discharge head 6 Substrate 7 Discharge port forming member 8 Discharge port 10 Pressure chamber 11 Energy generating element 13 Liquid supply port 15a, 15b Slit

Claims (1)

With the board
A discharge port forming member located on the substrate and formed of a photosensitive resin, which is provided with a plurality of discharge ports arranged in a first direction to discharge a liquid, and the plurality of discharge ports are provided between the discharge port and the substrate. The substrate has a discharge port forming member forming a plurality of pressure chambers communicating with an outlet, and the substrate is located on a surface facing the discharge port forming member, extends in the first direction, and has the plurality of pressure chambers. Has a liquid supply port that communicates with
Center said discharge port forming member, have a two slits extending said liquid supply port and the surface opposed to said first direction, said two slits extending in the first direction of the liquid supply port The thickness of the discharge port forming member between the two slits, which is provided line-symmetrically with respect to the line, is such that the discharge port is formed at the end of the discharge port forming member in the second direction orthogonal to the first direction. Equal to the thickness of the member,
A beam extending in the first direction to form a side wall of the slit, a first filter located in front of a part of the pressure chamber and separated from the beam, and a front surface of another pressure chamber from the beam. a beam-like second filter extends to have a liquid discharge head.

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