JP7682680B2 - Liquid ejection device, print head, and method for manufacturing the print head - Google Patents

Description

The present invention relates to a liquid ejection device that ejects liquid stored in a storage section from a head section, a print head, and a method for manufacturing a print head.

A liquid ejection device that ejects liquid from an ejection port to record on a recording medium such as paper has a storage section that stores the ejected liquid. In the storage section, the internal pressure changes depending on the environment in which it is used (for example, the state of liquid ejected from the ejection port). Therefore, pressure changes inside the storage section can be suppressed by providing a pressure suppression member made of an elastic material in the storage section. If there is a gap in the attachment part between the storage section and the pressure suppression member, the inside of the storage section will not be sealed, and liquid will leak from the gap or drip from the ejection port of the print head.

Incidentally, Patent Document 1 discloses that by sealing the entire gap at the boundary between the spherical applicator and the tip edge of the tip with a non-drying liquid, the coating liquid inside the tip does not solidify even if it is left for a long period of time, and a passage for the coating liquid is secured.

By applying the technology of Patent Document 1 to the liquid storage section of a liquid ejection device, it may be possible to prevent liquid leakage and liquid dripping from the print head.

Japanese Patent Application Publication No. 7-222949

However, if the technology of Patent Document 1 is applied to the liquid storage section of a liquid ejection device and the entire mounting surface of the pressure suppression member is sealed with a sealing material, the amount of sealing material used will increase, and it may become difficult to achieve sealing with a simple configuration.

The present invention therefore provides a liquid ejection device, print head, and method for manufacturing a print head that can prevent liquid leakage and dripping from the print head, and can be sealed with a simple configuration.

Therefore, the liquid ejection device of the present invention is a liquid ejection device having a storage section capable of storing liquid, and a pressure suppression member joined to the storage section and suppressing changes in the internal pressure of the storage section, and equipped with a print head that ejects the liquid stored in the storage section, wherein the storage section comprises an inner wall surface of the storage section to the back surface of the top surface, an inner surface of a hole provided in the top surface, and a groove provided continuously on the top surface, and a liquid sealing material is present between the storage section and the pressure suppression member to seal the space between them, and the liquid sealing material is the liquid stored in the storage section.

The present invention provides a liquid ejection device, a print head, and a method for manufacturing a print head that can prevent liquid leakage and dripping from the print head, and also prevent increases in costs.

FIG. 2 is a perspective view showing a main part of the liquid ejection device. FIG. 2 is a perspective view showing a print head. FIG. 2 illustrates a print head. 6 is an enlarged view of a joint between an ink storage section and a pressure suppression member; FIG. The contents and results of an experiment verifying the effects of the present invention. 1 is a schematic diagram showing a case where dust (foreign matter) is sandwiched between the sealing surfaces. 6 is an enlarged view of a joint between an ink storage section and a pressure suppression member; FIG. FIG. 4 is a diagram showing grooves provided in a print head. FIG. 4 is a diagram showing the ink storage section during a printing operation. FIG. FIG.

First Embodiment
A first embodiment of the present invention will now be described with reference to the drawings.

Figure 1 is a perspective view showing the main parts of a liquid ejection device 1 to which the present invention can be applied. The liquid ejection device 1 prints on the medium 6 by ejecting liquid (hereinafter also referred to as ink) from the print head 100 onto the medium 6 while alternately moving the print head 100 in the main scanning direction and moving the medium 6 in the sub-scanning direction.

The liquid ejection device 1 comprises a carriage 2 which carries the print head 100 and moves back and forth, a transport roller 3 which transports the medium 6, an ink tank 200 which contains ink, and a tube 4 which connects the ink tank 200 and the print head 100. The liquid ejection device 1 further comprises a first shaft 8 and a second shaft 9 which guide the moving carriage 2, and a cap unit 7 which caps the print head 100. When not printing, the print head 100 waits at the position of the cap unit 7 with the nozzle portion of the print head 100 sealed by a cap provided on the cap unit 7.

Figure 2 is a perspective view of the print head 100. The print head 100 has a first recording element board 110 (mainly for black) and a second recording element board 111 (mainly for colors) that eject ink for printing. A support member 120 that supports each recording element board is fixed to the head section 150 and is connected to an electrical wiring tape 130 and an electrical connection section 140 to send electrical signals for ejection to each recording element board. Each recording element board receives an electrical signal via the electrical connection member 140.

Figure 3 shows the print head 100. The print head 100 has an ink storage section 160 capable of storing ink therein. The head section 150 of the print head 100 is a member that fixes the print head 100 to the liquid ejection device 1, and is equipped with a recording element substrate 110 (111) for ejecting ink, an electric wiring tape 130, an electric connection member 140, and a filter 155. The head section 150 and the ink storage section 160 are hermetically joined on top of the filter 155 by fixing them with a seal member 170 sandwiched therebetween.

Since pressure changes occur inside the ink storage unit 160 due to the influence of the environment and the rocking caused by carriage movement during printing, a pressure suppression member 180 is provided on the top of the ink storage unit 160 to suppress internal pressure changes. The pressure suppression member 180 is made of an elastic body with an internal space, and by pressing and fixing the pressure suppression member 180 against the ink storage unit 160 with a pressing member 190, the ink storage unit 160 and the pressure suppression member 180 are hermetically joined at the sealing surface 181.

The print head 100 is inspected for leaks after assembly, but the inspection may result in a negative judgment. Possible causes for this are dust being caught between the ink storage section 160 and the pressure suppression member 180 during the assembly process, or the pressure suppression member 180 being deformed. Alternatively, a portion of the sealing surface 181 may be missing. If dust is caught, the pressure suppression member 180 is deformed, or the sealing surface 181 is missing, a gap will form at the joint between the ink storage section 160 and the pressure suppression member 180, and air will flow in through the gap, causing the seal to be lost. Therefore, in this embodiment, a liquid sealant is used to seal the gap between the ink storage section 160 and the pressure suppression member 180.

Figure 4 is an enlarged view of the joint between the ink storage section 160 and the pressure suppression member 180. In this embodiment, with the ink storage section 160 and the pressure suppression member 180 joined together, liquid sealant 185 is applied along the outer edge of the pressure suppression member 180. By applying the liquid sealant 185 in this manner to seal the gap, the inside of the ink storage section 160 can be kept sealed even if dust gets caught in the joint, the pressure suppression member 180 deforms, or a gap occurs due to partial loss of the sealing surface 181.

It is possible to apply the liquid sealant 185 to the entire sealing surface 181, but applying the liquid sealant 185 to the entire sealing surface 181 would require a large amount of application, which would increase costs. It is also possible that the liquid may flow out to the inside of the pressure suppression member 180 or into the communication port of the ink storage section 160. For this reason, it is preferable to apply the liquid sealant 185 along the outer edge of the joint after joining the pressure suppression member 180.

Figures 5 (a) and (b) show the contents and results of an experiment verifying the effects of the present invention. A wire 183 with diameters of 40/25/15 μm was sandwiched between the ink storage section 160 and the pressure suppression member 180, and the gap 182 created by the wire 183 was measured. In addition, with the gap 182 created by the wire 183, the presence or absence of liquid dripping from the print head 100 was confirmed in a state where no liquid sealant was applied and in a state where liquid sealant 185 was applied.

The gap 182 that occurs when a wire 183 with a diameter of 40 μm is sandwiched is 15 μm, and in a dry state without applying liquid sealant, liquid dripping occurred within one day. In contrast, when liquid sealant 185 was applied, no liquid dripping occurred from the print head 100 even after being left for a long period of time.

When a wire 183 with a diameter of 25 μm was sandwiched, the gap 182 that formed was 9 μm, and in a dry state without liquid application, liquid dripping occurred within one day.

The gap 182 that was created when a wire 183 with a diameter of 15 μm was sandwiched was 6 μm, and even when left in a dry state without applying liquid sealant for a long period of time, no liquid dripped from the print head 100.

Based on the above results, we believe that by applying liquid sealant 185 along the outer edge of the pressure suppression member 180, even if a gap 182 occurs, it will be sealed with liquid sealant 185, and liquid will not drip from the print head 100.

Thus, the liquid sealing material 185 is required to be able to seal the expected gap (6 to 15 μm) and to have optimal physical properties (viscosity, etc.) for sealing. In this embodiment, the liquid sealing material 185 is a non-volatile, non-hardening material with high viscosity. Furthermore, it is more preferable to use a liquid sealing material 185 that contains at least one of the materials contained in the ink used in the liquid ejection device 1. Even more preferably, all of the materials contained in the liquid sealing material 185 are contained in the ink. This is because even if the liquid sealing material 185 comes into contact with the ink and a component in the liquid sealing material 185 flows into the ink, if that component is a component used in the ink, the effect on the quality of the ink can be suppressed. In this embodiment, general glycerin (viscosity: 1412 mPa·s (20°C)) and acetylenol (Kawaken Fine Chemical Acetylenol E100) are used as the liquid sealing material 185.

Figure 6(a) is a schematic diagram of what happens when dust (foreign matter) is sandwiched between the sealing surface 181, and Figure 6(b) is a cross-sectional view taken along line VIb-VIb in Figure 6(a) with the liquid sealing material 185 omitted. When dust (foreign matter) is sandwiched between the sealing surface 181, the pressure suppression member 180, which is an elastic member, deforms, and a gap 182 is created in part of the sealing surface 181. Liquid sealing material 185 flows into the resulting gap 182 by capillary action, sealing the gap 182. The liquid sealing material 185 seals the gap 182, resulting in an airtight state for the pressure suppression member 180 and the inside of the ink storage section 160.

In this embodiment, the liquid sealant 185 is applied along the outer edge of the pressure suppression member 180, but it is sufficient that the liquid sealant 185 can flow into the gap when a gap occurs between the ink storage section 160 and the pressure suppression member 180. In other words, it is sufficient that the liquid sealant 185 is applied to the outer edge of the joint surface between the ink storage section 160 and the pressure suppression member 180.

In this way, the liquid sealant is applied along the outer edge of the joint surface between the ink storage section 160 and the pressure suppression member 180. This makes it possible to provide a liquid ejection device, print head, and print head manufacturing method that can suppress liquid leakage and dripping from the head section and also suppress increases in costs.

Second Embodiment
A second embodiment of the present invention will be described below with reference to the drawings. Note that since the basic configuration of this embodiment is similar to that of the first embodiment, only the characteristic configuration will be described below.

Figure 7 is an enlarged view of the joint between the ink storage unit 160 and the pressure suppression member 180 of this embodiment. In this embodiment, the joint between the ink storage unit 160 and the pressure suppression member 180 is provided with a convex portion 191 that protrudes toward the pressure suppression member 180, and the surface of the convex portion 191 serves as the joint surface. By providing the convex portion 191 on the ink storage unit 160 in this manner, a gap 182 is formed between the pressure suppression member 180 and the ink storage unit 160. The liquid sealant 185 flows into the gap 182 between the pressure suppression member 180 and the ink storage unit 160, but the area in which it flows is from the outer edge of the pressure suppression member 180 to the convex portion 191, and it does not flow from the convex portion 191 to the inside. Therefore, according to this embodiment, the amount of liquid sealant 185 flowing into the gap can be controlled. In this way, the liquid sealing material 185 seals the gap 182 between the pressure suppression member 180 and the ink storage section 160, so that the inside of the pressure suppression member 180 and the ink storage section 160 are sealed.

Third Embodiment
Hereinafter, the third embodiment of the present invention will be described with reference to the drawings. Since the basic configuration of this embodiment is the same as that of the first embodiment, the following will describe the characteristic configuration. As in the second embodiment, this embodiment also includes a protrusion 191.

8(a) is a diagram showing a groove 302 provided in the print head 300 in this embodiment, and FIG. 8(b) is a diagram showing the groove 302 on the top surface 306 of the ink storage section 301. The ink storage section 301 provided in the print head 300 has a groove 302 extending in the direction of the arrow Z along the inner wall surface 303 on both sides in the direction of the arrow X. The groove 302 extends in the direction of the arrow Z along the inner wall surface 303 from the surface of the ink storage section 301 sealed by the seal member 170, and reaches the top surface back surface 304. The groove 302 further extends toward the center of the ink storage section 301 along the top surface back surface 304, and further extends in the direction of the arrow Z along the inner surface of a hole portion 305 provided in the center of the ink storage section 301, and reaches the top surface 306 of the ink storage section 301. The groove 302 reaches the top surface 306 and then extends further along the top surface 306 from the center of the ink storage section 301 outward to the protrusion 191.

In this way, the ink storage section 301 is provided with a groove 302 that continues from the inner wall surface 303 to the top surface 306, and the ink 210 in the ink storage section 301 is transported along the groove 302 to the convex portion 191 by capillary action. The ink transported to the convex portion 191 spreads in a ring shape along the convex portion 191 as shown in FIG. 8B by capillary action occurring between the convex portion 191 and the pressure suppression member 180. The ring-shaped ink 210 forms a liquid bridge in the gap between the pressure suppression member 180, the convex portion 191, and the top surface 306, forming a meniscus. In this way, the meniscus formed between the pressure suppression member 180 and the top surface 306 along the convex portion 191 allows the inside of the ink storage section 301 to be sealed.

Figure 9 shows the ink storage section 301 during a printing operation. If there is an obstacle such as dust or molding defects inside the groove 302, the ink 210 may stop halfway through the groove 302. However, as shown in Figure 9, the grooves 302 are formed on the inner walls of the ink storage section 301 on both sides in the main scanning direction (predetermined direction) in which the print head 100 moves. By forming the grooves 302 in this way, the inertial force caused by the reciprocating movement of the print head 100 acts on the ink 210, and the water surface of the ink 210 rises and falls, allowing the ink 210 to reach the convex portion 191 along the grooves 302 by overcoming the dust or molding defects. If the dust or molding defects are located at the top of the ink storage section 301, if the amount of ink 210 in the ink storage section 301 is small, it is possible that the ink 210 will not reach the dust or molding defects. In that case, it is sufficient to refill the ink 210.

The amount of ink 210 that rises up along the groove 302 due to capillary action is explained below.

The height h that a liquid rises up a vertical tube due to capillary force is:

Here,
T: Surface tension of the liquid ρ: Density of the liquid r: Inner diameter (radius) of the tube
θ: Contact angle, in the embodiment,
T: 0.030 or 0.036 [N/m] (hereafter, calculate using T = 0.030 [N/m], whichever is more difficult to climb)
ρ: 1000 [kg/ ^m3 ]
r: r [m]
θ: 30 [deg]
Let us assume that.

Substituting these values into equation (1),

Here, the equivalent radius of a groove with a side length of d [m] is re [m],

In this embodiment, the height from the bottom surface of the ink storage unit 301 to the top surface 306 is 19 mm, so by substituting these values into formula (2),

Therefore, if the groove has a width and depth of 0.4 mm or less on each side, it can transport ink 210 from the bottom surface of ink storage section 301 to top surface 306.

When the user fills the print head 100 with ink, the ink 210 fills the ink storage section 301 to about half its height. Therefore, the lower end of the groove 302 in the direction of the arrow Z (see FIG. 8) needs to be located below half the height from the bottom surface of the ink storage section 301 to the top surface 306. Therefore, in use, in formula (2),

About this amount is sufficient, and when we calculate this,

This shows that for practical purposes, a groove that is 0.8 mm square or less (groove width 0.8 mm or less) is sufficient.

Figures 10 and 11 are diagrams showing modified examples of this embodiment. Figure 10(a) is an example in which two continuous ribs 307 are provided from the bottom of the ink storage section to the top surface 306. As shown in Figure 10(a), two continuous ribs 307 may be formed, and a groove may be formed between the two ribs 307 to utilize the capillary phenomenon of the ink 210. Figure 10(b) is an example in which a groove 302 is provided on the top surface 306, and two continuous ribs 307 are provided in other parts. Also, Figure 10(c) shows two ribs 307 provided halfway up the top surface 306, and a groove 302 is provided halfway up. In this way, a configuration in which the two ribs 307 are switched to a groove 302 halfway up the top surface 306 may be used.

Furthermore, as shown in FIG. 11, a groove 302 may be provided on at least one side of the inner wall of the ink storage section 301 in the direction of the arrow X. Grooves may also be provided on the inner wall of the ink storage section 301 in a direction other than the direction of the arrow X. Furthermore, the configuration shown in FIG. 11 may be appropriately combined with the configuration shown in FIG. 10.

REFERENCE SIGNS LIST 1 Liquid ejection device 2 Carriage 100 Print head 150 Head section 160 Ink storage section 180 Pressure suppression member 182 Gap 185 Liquid seal material 210 Ink 302 Groove 306 Top surface 307 Rib

Claims (15)

A storage unit capable of storing a liquid;
a pressure suppression member joined to the storage portion and suppressing a change in an internal pressure of the storage portion, the pressure suppression member being connected to the storage portion and configured to suppress a change in an internal pressure of the storage portion,
The storage section includes an inner wall surface of the storage section , a back surface of the top surface, an inner surface of a hole provided in the top surface, and a groove provided continuously on the top surface,
a liquid sealant is present between the storage portion and the pressure suppression member to seal the space therebetween;
The liquid discharge device according to claim 1, wherein the liquid sealing material is a liquid stored in the storage section. The liquid ejection device according to claim 1, wherein the liquid sealing material is capable of sealing gaps of 6 to 15 μm. The liquid ejection device according to claim 1 or 2, wherein the pressure suppression member is pressed against the storage section by a pressing member. The liquid ejection device according to any one of claims 1 to 3, wherein the pressure suppression member is made of an elastic material. The liquid ejection device according to claim 4, wherein the pressure suppression member joined to the storage portion has a space communicating with the inside of the storage portion. The liquid ejection device according to any one of claims 1 to 5, wherein the storage section has a protrusion that protrudes toward the pressure suppression member, and the protrusion and the pressure suppression member are joined. The liquid ejection device according to claim 1, characterized in that the groove is formed from the inner wall surface of the storage section to the back surface of the top surface, the inner surface of a hole in the top surface, and two ribs that are continuously provided on the top surface. The storage unit reciprocates in a predetermined direction together with the print head,
The liquid ejection device according to claim 7 , wherein the groove is provided on at least one inner wall of the storage portion in the predetermined direction. The liquid ejection device according to claim 8, characterized in that the groove is provided on both inner walls of the storage section in the specified direction. The liquid ejection device according to any one of claims 1 to 9, characterized in that the width of the groove is 0.8 mm or less. The liquid ejection device according to any one of claims 1 to 10, characterized in that the groove is provided below half the height from the bottom surface to the top surface of the ink storage section. A storage unit capable of storing a liquid;
a pressure suppression member joined to the storage portion and suppressing an internal pressure change of the storage portion,
The storage section includes an inner wall surface of the storage section, a back surface of the top surface, an inner surface of a hole provided in the top surface, and a groove provided continuously on the top surface,
a liquid sealant is present between the storage portion and the pressure suppression member to seal the space therebetween;
The print head according to claim 1, wherein the liquid sealing material is a liquid stored in the storage portion. The print head according to claim 12 , wherein the storage portion has a protrusion protruding toward the pressure suppression member, the protrusion being joined to the pressure suppression member. a protrusion is provided between the storage portion and a sealing surface of the pressure suppression member,
2. The liquid ejection device according to claim 1, wherein the liquid sealant is provided between a top surface of the storage section inside the protrusion and a sealing surface of the pressure suppression member. a protrusion is provided between the storage portion and a sealing surface of the pressure suppression member,
13. The print head according to claim 12, wherein the liquid sealant is provided between a top surface of the storage portion inside the protrusion and a sealing surface of the pressure suppression member.

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