Liquid dispensing head, liquid dispensing unit, and device for dispensing liquid

Abstract

To adequately exhibit a damping function of a damper part by achieving both suppression of damage to the damper part provided in a liquid discharge head and restriction of deterioration of the damping function.SOLUTION: In a liquid discharge head, liquid in pressure chambers 122 is discharged from nozzles 111 by fluctuating pressure in the pressure chambers 122 using actuator members 124, and the pressure fluctuation of liquid is attenuated by a damper part 103 held by holding substrates 104, 102. In the damper part, compressive stress is generated in a damper surface direction orthogonal to a thickness direction, and a linear expansion coefficient in the damper surface direction is asymmetric relative to a center in the thickness direction.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a liquid ejection head, a liquid ejection unit, and an apparatus for ejecting a liquid.

Background Art

[0002] Conventionally, it is known that a liquid in a pressure chamber is ejected from a nozzle by varying the pressure in the pressure chamber with an actuator member, and the pressure fluctuation of the liquid is attenuated by a damper portion held on a holding substrate.

[0003] For example, Patent Document 1 discloses a liquid ejection head provided with a damping membrane (damper portion) that alleviates a change (pressure fluctuation) in the internal pressure of a manifold serving as a liquid flow path. A cavity is formed below the damping membrane. This damping membrane is formed by thinning a part of a Si substrate (holding substrate) on which the manifold is formed.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the damper portion is formed by thinning a part of the holding substrate that holds it, the material of the damper portion is restricted by the material of the holding substrate. As a result, there is a problem that it is difficult to sufficiently exhibit the damper function.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention provides a liquid ejection head that ejects a liquid in a pressure chamber from a nozzle by varying the pressure in the pressure chamber with an actuator member, and attenuates the pressure fluctuation of the liquid by a damper portion held on a holding substrate, wherein the damper portion The coefficient of linear expansion is smaller than that of the aforementioned holding substrate, generates a compressive stress in the damper surface direction orthogonal to the thickness direction It is configured in such a way as and the linear expansion rate in the damper surface direction is asymmetric with respect to the center in the thickness direction This results in buckling that causes bending on one side in the thickness direction.It is characterized by being composed of seaweed. [Effects of the Invention]

[0006] According to the present invention, the damper function of the damper section can be fully utilized. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic exploded perspective view showing the liquid dispensing head of the embodiment. [Figure 2] A schematic cross-sectional view of the liquid discharge head along the nozzle arrangement direction. [Figure 3] A schematic cross-sectional view of the liquid discharge head in a direction perpendicular to the nozzle arrangement direction. [Figure 4] (a) to (c) are explanatory diagrams showing an example of a joining method between the frame member and the damper part of the liquid discharge head. [Figure 5] A schematic cross-sectional view illustrating the actuator circuit board of the liquid discharge head. [Figure 6] A cross-sectional view showing the damper in Comparative Example 1. [Figure 7] An explanatory diagram showing how damage occurs to the damper in Comparative Example 1. [Figure 8] A cross-sectional view showing the damper 131 in Comparative Example 2. [Figure 9] An explanatory diagram showing how the damper in Comparative Example 2 experiences wavy buckling. [Figure 10] A cross-sectional view showing an example of a damper in an embodiment (Example 1). [Figure 11] An explanatory diagram showing how buckling occurs on one side in the thickness direction of the damper in the embodiment. [Figure 12] A cross-sectional view showing another example of the damper in the embodiment (Example 2). [Figure 13] A cross-sectional view showing yet another example of the damper in the embodiment. [Figure 14] A cross-sectional view showing yet another example of the damper in the embodiment. [Figure 15] A schematic diagram of an example of a device for dispensing liquid. [Figure 16] Schematic diagram in another example of a device for discharging a liquid. [Figure 17] Schematic diagram in an example of a liquid discharge unit. [Figure 18] Schematic diagram in another example of a liquid discharge unit.

Mode for Carrying Out the Invention

[0008] Hereinafter, the liquid discharge head according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments shown below, and can be changed within the scope that those skilled in the art can conceive, such as other embodiments, additions, modifications, deletions, etc., and as long as the functions and effects of the present invention are achieved in any aspect, it is included in the scope of the present invention.

[0009] The liquid discharge head in the present embodiment is a liquid discharge head that discharges the liquid in the pressure chamber from the nozzle by varying the pressure in the pressure chamber by an actuator member, and has a function of attenuating the pressure fluctuation of the liquid by a damper portion held on a holding substrate.

[0010] FIG. 1 is an exploded perspective view schematically showing the liquid discharge head of the present embodiment. The liquid discharge head of the present embodiment has a nozzle substrate 101, an actuator substrate 102, a damper portion 103, and a frame member 104.

[0011] The nozzle substrate 101 has nozzles 111 for discharging a liquid (for example, ink). The actuator substrate 102 has a common liquid chamber 121 and is joined to the nozzle substrate 101. The illustrated common liquid chamber 121 is schematically shown and is not limited to what is shown. [[ID=3⑤]] The frame member 104 has a recess described later, a damper portion 103 is formed, and the damper portion 103 is joined to the actuator substrate 102 by an adhesive 151.

[0012] The damper portion 103 on the frame member 104 forms a part of the wall surface of the common fluid chamber 121 when the frame member 104 is joined to the actuator substrate 102, and this portion becomes the damper 131. The shape of the damper 131 shown is schematic and is not limited to that shown.

[0013] By using the damper section 103, the vibration of the damper 131 can suppress fluid vibration (pressure fluctuation). For example, by using the damper section 103, vibration of the liquid flowing through a tributary (flow channel) formed on the actuator substrate 102 can be suppressed. Also, when one nozzle unit is considered as a channel, the propagation of vibrations generated in one channel to other channels can be suppressed.

[0014] Next, the configuration of the damper section 103 in this embodiment will be described. Figure 2 is a schematic cross-sectional view of the liquid discharge head of this embodiment along the nozzle arrangement direction, and corresponds to the schematic cross-sectional view AA in Figure 1. Figure 3 is a schematic cross-sectional view of the liquid discharge head in this embodiment, perpendicular to the nozzle arrangement direction, and corresponds to the schematic cross-sectional view of BB in Figure 1.

[0015] As shown in the figure, the frame member 104 has a recess 141. The recess 141 prevents the damper 131 from coming into contact with the frame member 104, for example, if the damper 131 deforms. The recess 141 may also be referred to as a cavity, damper region, damper chamber, etc.

[0016] In the examples shown in Figures 2 and 3, the damper portion 103 is integrated onto the frame member 104 using a semiconductor process. Specifically, for example, the damper portion 103, consisting of a single-layer or multi-layer structure, can be fabricated by first depositing it on a wafer on which the frame member 104 is formed, and then removing the portion that will become the recess 141 in the frame member 104. In this case, a method such as etching using a sacrificial layer can be employed to form the recess 141 in the frame member 104.

[0017] In this embodiment, the damper portion 103 is formed on the frame member 104 and integrated (joined) with it, but the method of joining the frame member 104 and the damper portion 103 is not limited to this.

[0018] Figures 4(a) to 4(c) are explanatory diagrams showing examples of joining methods between the frame member 104 and the damper portion 103, respectively. The example shown in Figure 4(a) is one in which the frame member 104 and the damper portion 103 are joined with adhesive 151. In this case, for example, the damper portion 103 can be attached to the frame member 104 with adhesive 151, and then the substrate portion of the wafer can be removed.

[0019] The example shown in Figure 4(b) illustrates the joining method employed in this embodiment, in which the damper portion 103 is formed on the frame member 104 and integrated into a single unit.

[0020] The example shown in Figure 4(c) also employs the joining method used in this embodiment, in which the damper portion 103 is formed on the frame member 104 and integrated. However, in the example shown in Figure 4(c), the ceiling portion of the recess 141 is removed in order to form the recess 141. Even when there is no ceiling portion, it is still included in the "recess" as defined herein and is referred to as the damper region, etc.

[0021] The actuator substrate 102 has a common liquid chamber 121, and when the frame member 104 on which the damper portion 103 is formed is joined to the actuator substrate 102, the damper 131 forms part of the wall surface of the common liquid chamber 121. For example, if vibration occurs in the liquid in the common liquid chamber 121, the damper 131 vibrates, suppressing the vibration of the liquid. This can mitigate pressure propagation to adjacent channels and fluctuations in ink flow rate. For example, it can mitigate pressure fluctuations in the liquid chambers and flow paths within the actuator substrate 102.

[0022] Although Figures 2 and 3 only show the common liquid chamber 121 in the actuator substrate 102, the actuator substrate 102 may also have individual liquid chambers (pressure chambers), piezoelectric elements, flow channels, etc. For example, the individual liquid chambers communicate with the nozzles 111 of the nozzle substrate 101. The shape, arrangement, and number of nozzles 111 are not limited to those shown in the figures and can be selected as appropriate.

[0023] Figure 5 is a schematic cross-sectional view illustrating the actuator substrate 102. The actuator substrate 102 of this embodiment includes, for example, a diaphragm 125 and a flow channel plate 127. The actuator substrate 102 also has individual liquid chambers 122 as pressure chambers communicating with the nozzle 111, as well as a fluid resistor 123, a piezoelectric element 124 as an actuator member, a flow channel 126, etc. An introduction channel is provided between the flow channel 126 and the fluid resistor 123 to introduce liquid from the flow channel 126 (common flow channel) to the fluid resistor 123. In this embodiment, pressure is applied to the liquid in the individual liquid chamber 122 by the piezoelectric element 124, and the liquid is discharged from the nozzle 111. Liquid is supplied to the individual liquid chamber 122 from the common liquid chamber 121 through the flow channel 126.

[0024] Next, the details of the damper section 103 in this embodiment will be described. In this embodiment, the damper portion 103 is held by a holding substrate (frame member 104 or actuator substrate 102) such that compressive stress is generated in a direction perpendicular to the thickness direction (damper surface direction), and is configured so that the coefficient of linear expansion in the damper surface direction is asymmetric with respect to the center in the thickness direction. The damper portion 103 configured in this way may be a single-layer structure or a multi-layer structure (laminated structure).

[0025] However, making the damper a multilayer structure has the advantage of making it easier to control the damper's physical properties. For example, the type (material) and thickness of each layer can be appropriately selected, and the number of layers can be appropriately selected. If the damper is a single layer, it is not possible to change the physical properties which depend on the type of film. On the other hand, with a multilayer structure, stress and other properties of the damper may be unevenly distributed, and the damper may not be able to perform its function. Therefore, in this embodiment, an example in which the damper is a multilayer structure consisting of multiple layers will be explained.

[0026] One method is to form the damper portion 103 by thinning the same wafer as the frame member 104, which is the holding substrate for the damper portion 103, and the actuator substrate 102. However, the material of the damper portion 103 is limited to the same material as the frame member 104, etc., which is the holding substrate. In this case, the degree of freedom in selecting the material for the damper portion is low, making it difficult to obtain a damper portion that can fully perform its damping function. In contrast, if the damper portion 103 is formed from a material different from the frame member 104, etc., which is the holding substrate, and this damper portion 103 is held by the frame member 104, etc., the degree of freedom in selecting the material for the damper portion 103 is increased, making it easier to obtain a damper portion that can fully perform its damping function.

[0027] However, if the retaining substrate such as the frame member 104 and the damper portion 103 are made of different materials, the coefficient of linear expansion of the damper portion 103 in the damper surface direction will differ between the frame member 104 and the damper portion 103.

[0028] Figure 6 is a cross-sectional view showing damper 131' in Comparative Example 1. The damper 131' shown in Figure 6 is an example of a three-layer damper structure in which a SiN film 303', which generates relatively strong tensile stress when formed on a frame member 104, is sandwiched between HTO film (SiO2) 304', which generates relatively weak compressive stress. This damper 131' is configured such that the coefficient of linear expansion in the damper surface direction is symmetrical with respect to the center in the thickness direction. Overall, this damper 131' generates tensile stress in the damper surface direction, and in this case, as shown in Figure 7, excessive tensile stress F is applied to the damper 131' due to the stress S applied during the manufacturing process of the liquid discharge head, making the damper 131' prone to failure.

[0029] Figure 8 is a cross-sectional view showing damper 131'' in Comparative Example 2. The damper 131'' shown in Figure 8 is an example of a single-layer damper made of a silicon thermal oxide film (SiO2) 305'' that generates strong compressive stress when formed on the frame member 104. Overall, this damper 131'' generates compressive stress in the direction of the damper surface, causing the damper 131'' to become loose, thus reducing the likelihood of damage to the damper 131'' even when stress is applied.

[0030] However, when the damper 131'' becomes loose, buckling occurs in the damper 131''. At this time, as shown in Figure 9, it was found that when wave-like buckling (buckling in which the direction of buckling (direction of deflection) differs depending on the location) occurs in the damper 131'', the response to liquid pressure fluctuations deteriorates, and the damping function of the damper part decreases.

[0031] Figure 10 is a cross-sectional view showing an example of the damper 131 in this embodiment (Example 1). In this embodiment, the damper portion 103, which is held on a holding substrate such as a frame member 104 so as to generate compressive stress in the damper surface direction, is configured such that the coefficient of linear expansion in the damper surface direction is asymmetric with respect to the center in the thickness direction. Specifically, the damper portion 103 of Embodiment 1 shown in Figure 10 has a two-layer structure consisting of an HTO film (SiO2) 304 that generates relatively weak compressive stress and a silicon thermal oxide film (SiO2) 305 that generates relatively strong compressive stress, with the HTO film 304 facing the frame member 104.

[0032] Thus, by making the damper, which experiences compressive stress in the damper surface direction, have an asymmetrical coefficient of thermal expansion, damage to the damper can be suppressed, and as shown in Figure 11, buckling can be caused in the damper 131 to deflect to one side in the thickness direction across the entire damper surface. Furthermore, if the buckling that occurs in the damper 131 is a buckling that deflects to one side in the thickness direction across the entire damper surface, a continuous response to liquid pressure fluctuations becomes possible compared to the damper 131' which experiences wavy buckling as shown in Figure 9, and the deterioration of the damper function of the damper section 103 is suppressed.

[0033] Figure 12 is a cross-sectional view showing another example (Example 2) of the damper 131 in this embodiment. The damper portion 103 of Embodiment 2 shown in Figure 12 is also configured such that, when held on a holding substrate such as a frame member 104, compressive stress is generated in the damper surface direction, the coefficient of linear expansion in the damper surface direction is asymmetrical with respect to the center in the thickness direction. Specifically, the damper portion 103 of Embodiment 2 shown in Figure 12 has a three-layer structure in which a PS (polysilicon) film 302 is interposed between an HTO film (SiO2) 304, which generates relatively weak compressive stress, and a silicon thermal oxide film (SiO2) 305, which generates relatively strong compressive stress, with a compressive stress intermediate between these films.

[0034] The damper section 103 in Embodiment 2 shown in Figure 12 is configured with such a three-layer structure that the compressive stress generated in the damper section 103 gradually increases from the frame member 104 toward the actuator substrate 102. This suppresses abrupt stress changes in the damper section 103, making it less likely to break.

[0035] It should be noted that the materials and number of layers of each layer constituting the damper portion 103 in this embodiment are not limited to those of this embodiment and can be changed as appropriate. For example, if the damper portion 103 is held on a holding substrate such as a frame member 104 so that compressive stress is generated in the damper surface direction, it may include a film that generates tensile stress, such as a SiN film 303, as shown in Figures 13 and 14. However, in this case, the film thickness of the film that generates tensile stress, such as the SiN film 303, and the film that generates compressive stress, such as the HTO film (SiO2) 304, should be adjusted as appropriate so that the overall structure is asymmetrical in the thickness direction and compressive stress is generated in the damper surface direction.

[0036] The damper section 103 has an elastic compliance of 7 × 10 -17 Pa -1 The above is preferable. To ensure the damper functions effectively, it is important to adjust the elastic compliance to a suitable range. By setting the damper's elastic compliance within the above range, it becomes easier to set the optimal layer configuration for the damper's function.

[0037] Furthermore, the elastic compliance of the damper section 103 is determined by the thickness of the damper and its Young's modulus, assuming the dimensions of the tributary through which the liquid flows remain unchanged. Although not limited, it is preferable that the Young's modulus of the damper section 103 be between 3 GPa and 200 GPa. In this case, it becomes easier to set the elastic compliance of the damper section 103 within the above-mentioned preferred range, and liquid propagation can be further suppressed.

[0038] The material constituting the layer of the damper portion 103 can be appropriately selected, and examples include Si, SiO2, SiN, PS (polysilicon), Al2O3, etc. By using these example materials, it becomes easier to bring the elastic compliance and Young's modulus into the above-mentioned preferred range. In addition to the above, organic materials obtained by vapor deposition or spin coating can also be used.

[0039] Next, we will describe the results of effectiveness verification tests conducted on the damper sections 103', 103'', and 103 of Comparative Examples 1 and 2, as well as Examples 1 and 2. Comparative Examples 1 and 2, and the damper sections 103', 103'', and 103 of Examples 1 and 2, were adjusted to generate the stresses shown in Table 1 below, with elastic compliances of 7 × 10⁻¹⁰ each. -17 Pa -1 I adjusted it to be as described above.

[0040] [Table 1]

[0041] In this effectiveness verification test, the components equipped with four damper sections from Comparative Examples 1 and 2 and Examples 1 and 2 were placed in a vacuum-sealed case, and their initial deflection and deformation behavior under pressure were observed using a laser microscope. Furthermore, it was confirmed whether damage to the damper section occurred during the manufacturing process of the liquid discharge head.

[0042] Regarding the initial deflection, it was confirmed that no buckling occurred in Comparative Example 1. This is thought to be because tensile stress is generated in the damper section 103', causing the damper 131' to be in a rigid state and thus suppressing buckling.

[0043] In contrast, buckling was confirmed to have occurred in Comparative Example 2 and Examples 1 and 2. This is thought to be because compressive stress was generated in the damper sections 103'',103, causing the dampers 131',131 to loosen and resulting in buckling.

[0044] However, while Comparative Example 2 exhibited buckling in a wavy state as shown in Figure 9, Examples 1 and 2 exhibited buckling in a state where the material deflected only on one side in the thickness direction, as shown in Figure 11. In particular, since Examples 1 and 2 both have a multi-layer structure, it is thought that they were able to generate greater deflection than a single-layer structure.

[0045] Furthermore, regarding the deformation behavior in response to pressure, a continuous response was confirmed for Comparative Example 1 and Examples 1 and 2, but a discontinuous response was confirmed for Comparative Example 2. This is thought to be due to the wavy state of buckling in Comparative Example 2, as shown in Figure 9.

[0046] Furthermore, the damper components of Comparative Example 1 and Examples 1 and 2, which exhibited appropriate deformation behavior under pressure, were introduced into the liquid discharge head assembly process to confirm whether the damper 131 was damaged. This confirmation was not performed for Comparative Example 2 because it did not exhibit damping function.

[0047] As a result, Comparative Example 1 developed a crack in the damper during the assembly process. This is thought to be because the damper portion 103' of Comparative Example 1 was under tensile stress, causing the membrane to be taut. Therefore, there was no margin for error in terms of stress and deformation during the assembly process, resulting in the crack.

[0048] In contrast, no damage such as cracking occurred in Examples 1 and 2. This is thought to be because the damper portion 103 in both Examples 1 and 2 was under compressive stress, causing the membrane to slacken, and this slack was able to absorb the stress and deformation during the assembly process.

[0049] In this embodiment, the damper portion 103 is controlled to bend in a convex shape toward the actuator substrate 102, as shown in Figure 11. However, conversely, the bending direction may be controlled to bend in a convex shape toward the frame member 104.

[0050] Next, an example of a liquid dispensing apparatus according to the present invention will be described with reference to Figures 15 and 16. Figure 15 is a plan view illustrating the main parts of the apparatus, and Figure 16 is a side view illustrating the main parts of the apparatus.

[0051] This device is a serial type device, and the carriage 403 reciprocates in the main scanning direction by the main scanning movement mechanism 493. The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is stretched across the left and right side plates 491A and 491B and holds the carriage 403 in a movable position. The carriage 403 is then reciprocated in the main scanning direction by the main scanning motor 405 via the timing belt 408 stretched between the drive pulley 406 and the driven pulley 407.

[0052] The carriage 403 is equipped with a liquid discharge unit 440 that integrates a liquid discharge head 404 and a head tank 441 according to the present invention. The liquid discharge head 404 of the liquid discharge unit 440 discharges liquids of various colors, such as yellow (Y), cyan (C), magenta (M), and black (K). The liquid discharge head 404 is also mounted with a nozzle row consisting of multiple nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and with the discharge direction facing downwards.

[0053] A supply mechanism 494 for supplying liquid stored outside the liquid discharge head 404 to the liquid discharge head 404 supplies the head tank 441 with liquid stored in the liquid cartridge 450.

[0054] The supply mechanism 494 consists of a cartridge holder 451, which is a filling section for mounting the liquid cartridge 450, a tube 456, a liquid delivery unit 452 including a liquid delivery pump, and the like. The liquid cartridge 450 is detachably mounted in the cartridge holder 451. Liquid is delivered from the liquid cartridge 450 to the head tank 441 via the tube 456 by the liquid delivery unit 452.

[0055] This device includes a transport mechanism 495 for transporting paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0056] The conveyor belt 412 attracts the paper 410 and transports it to a position opposite the liquid discharge head 404. This conveyor belt 412 is an endless belt and is stretched between the conveyor roller 413 and the tension roller 414. Attraction can be performed by electrostatic attraction or air suction.

[0057] Then, the conveyor belt 412 moves in a circular motion in the sub-scanning direction as the conveyor rollers 413 are rotationally driven by the sub-scanning motor 416 via the timing belt 417 and timing pulley 418.

[0058] Furthermore, a maintenance and recovery mechanism 420 is positioned on one side of the carriage 403 in the main scanning direction, to the side of the conveyor belt 412, for maintaining and recovering the liquid discharge head 404.

[0059] The maintenance and recovery mechanism 420 consists of, for example, a cap member 421 that caps the nozzle surface (the surface on which the nozzle is formed) of the liquid discharge head 404, and a wiper member 422 that wipes the nozzle surface.

[0060] The main scanning movement mechanism 493, the supply mechanism 494, the maintenance and recovery mechanism 420, and the transport mechanism 495 are mounted on a housing that includes side plates 491A, 491B, and a back plate 491C.

[0061] In this configured device, the paper 410 is fed onto the transport belt 412 and picked up, and the paper 410 is transported in the sub-scanning direction by the circumferential movement of the transport belt 412.

[0062] Therefore, by moving the carriage 403 in the main scanning direction and driving the liquid ejection head 404 in accordance with the image signal, liquid is ejected onto the stationary paper 410 to form an image.

[0063] Thus, since this device is equipped with a liquid discharge head according to the present invention, it can stably form high-resolution images.

[0064] Next, another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 17. Figure 17 is a plan view illustrating the main parts of the unit.

[0065] This liquid discharge unit consists of a housing portion comprising side plates 491A, 491B and a back plate 491C, a main scanning movement mechanism 493, a carriage 403, and a liquid discharge head 404, which are components of the device that discharges the liquid.

[0066] Furthermore, a liquid dispensing unit can also be configured by further attaching, for example, the side plate 491B of this liquid dispensing unit to at least one of the aforementioned maintenance and recovery mechanism 420 and supply mechanism 494.

[0067] Next, yet another example of the liquid dispensing unit according to the present invention will be described with reference to Figure 18. Figure 18 is a front view of the unit.

[0068] This liquid discharge unit consists of a liquid discharge head 404 to which a flow path component 444 is attached, and a tube 456 connected to the flow path component 444.

[0069] The flow path component 444 is located inside the cover 442. A head tank 441 can be included instead of the flow path component 444. Furthermore, a connector 443 for electrical connection to the liquid discharge head 404 is provided on the upper part of the flow path component 444.

[0070] In this application, "liquid dispensing device" refers to a device that includes a liquid dispensing head or liquid dispensing unit and drives the liquid dispensing head to dispense liquid. A liquid dispensing device includes not only devices that can dispense liquid onto objects to which liquid can adhere, but also devices that dispense liquid into air or into liquid.

[0071] This "liquid dispensing device" may also include means for feeding, transporting, and dispensing paper onto materials to which liquid can adhere, as well as pre-treatment devices, post-treatment devices, etc.

[0072] For example, "devices that dispense liquids" include image forming machines, which dispense ink to form images on paper, and three-dimensional molding machines, which dispense molding liquid into a powder layer formed in layers to create three-dimensional objects.

[0073] Furthermore, "devices that dispense liquid" are not limited to those that visualize meaningful images such as letters or figures through the dispensed liquid. For example, devices that form patterns that do not have meaning in themselves, or devices that create three-dimensional images, are also included.

[0074] The term "materials to which liquid can adhere" above refers to materials to which liquid can adhere, at least temporarily, including materials that adhere and solidify, or materials that adhere and penetrate. Specific examples include recording media such as paper, recording paper, film, and cloth; electronic components such as electronic circuit boards and piezoelectric elements; powder layers; organ models; and inspection cells. Unless otherwise specified, it includes all materials to which liquid can adhere.

[0075] The materials referred to as "materials to which liquid can adhere" above include paper, thread, fibers, fabrics, leather, metal, plastic, glass, wood, ceramics, building materials such as wallpaper and flooring, and textiles for clothing, as long as liquid can adhere to them, even temporarily.

[0076] Furthermore, "liquid" also includes inks, processing solutions, DNA samples, resists, patterning materials, binders, molding fluids, or solutions and dispersions containing amino acids, proteins, calcium, etc.

[0077] Furthermore, "liquid dispensing devices" include devices in which the liquid dispensing head and the surface to which the liquid can adhere move relative to each other, but are not limited to these. Specific examples include serial-type devices in which the liquid dispensing head moves, and line-type devices in which the liquid dispensing head does not move.

[0078] Other examples of "devices that dispense liquids" include processing liquid coating devices that dispense processing liquid onto the surface of paper for purposes such as modifying the surface of the paper, and injection granulation devices that granulate fine particles of raw materials by spraying a composition liquid, in which raw materials are dispersed in a solution, through a nozzle.

[0079] A "liquid dispensing unit" is a collection of components related to liquid dispensing, in which functional parts and mechanisms are integrated with a liquid dispensing head. For example, a "liquid dispensing unit" may include a combination of a liquid dispensing head with at least one of the following components: a head tank, carriage, supply mechanism, maintenance and recovery mechanism, and main scanning and moving mechanism.

[0080] Here, integration includes, for example, cases where the liquid dispensing head and functional components or mechanisms are fixed to each other by fastening, bonding, engaging, etc., or where one is held movably relative to the other. Furthermore, the liquid dispensing head and functional components or mechanisms may be configured to be detachable from each other.

[0081] For example, some liquid dispensing units, such as the liquid dispensing unit 440 shown in Figure 16, have a liquid dispensing head and head tank integrated into one unit. Others have a liquid dispensing head and head tank integrated into one unit, connected to each other by tubes or similar means. It is also possible to add a unit containing a filter between the head tank and the liquid dispensing head of these liquid dispensing units.

[0082] Additionally, some liquid dispensing units have an integrated liquid dispensing head and carriage.

[0083] Furthermore, some liquid dispensing units integrate the liquid dispensing head and the scanning mechanism by movably holding the liquid dispensing head in a guide member that constitutes part of the scanning mechanism. Additionally, as shown in Figure 17, some liquid dispensing units integrate the liquid dispensing head, carriage, and main scanning mechanism.

[0084] Furthermore, some liquid dispensing units integrate the liquid dispensing head, carriage, and maintenance / recovery mechanism by fixing a cap component, which is part of the maintenance / recovery mechanism, to a carriage to which the liquid dispensing head is attached.

[0085] Furthermore, as shown in Figure 18, some liquid discharge units have a head tank or a liquid discharge head to which a flow path component is attached, to which a tube is connected, integrating the liquid discharge head and the supply mechanism.

[0086] The main scanning movement mechanism shall include the guide member alone. The supply mechanism shall also include the tube alone and the loading section alone.

[0087] Furthermore, the "liquid discharge head" is not limited to any particular pressure generating means. For example, in addition to the piezoelectric actuator described in the above embodiment (which may use a multilayer piezoelectric element), a thermal actuator using an electrothermal conversion element such as a heating resistor, or an electrostatic actuator consisting of a diaphragm and a counter electrode may also be used.

[0088] Furthermore, in the terminology used in this application, image formation, recording, printing, copying, printing, and shaping are all considered synonymous.

[0089] The above is just one example; each of the following embodiments produces its own unique effects. [First aspect] The first embodiment is a liquid discharge head that discharges liquid (e.g., ink) from a nozzle 111 by fluctuating the pressure in a pressure chamber (e.g., individual liquid chamber 122) using an actuator member (e.g., piezoelectric element 124), and dampers the pressure fluctuations of the liquid by a damper portion 103 held on a holding substrate (e.g., frame member 104, actuator substrate 102), characterized in that the damper portion is configured such that compressive stress is generated in the damper surface direction perpendicular to the thickness direction, and the coefficient of linear expansion in the damper surface direction is asymmetric with respect to the center in the thickness direction. Conventional liquid dispensing heads form a damper section by thinning a portion of the holding substrate, thus limiting the material of the damper section to the same material as the holding substrate. In this case, the degree of freedom in selecting the material for the damper section is low, making it difficult to obtain a damper section that can fully perform its damping function. In contrast, if the damper section is formed from a material different from the holding substrate and this damper section is held by the holding substrate, the degree of freedom in selecting the material for the damper section is increased, making it easier to obtain a damper section that can fully perform its damping function. However, if the retaining substrate and the damper portion are made of different materials, the coefficient of linear expansion in the direction perpendicular to the thickness direction of the damper portion (damper surface direction) may differ between the retaining substrate and the damper portion. In this case, for example, if the damper portion is formed from a material with a higher coefficient of linear expansion than the retaining substrate, the damper portion will be held by the retaining substrate in such a way that tensile stress is generated in the damper surface direction after the damper portion is cooled after joining the retaining substrate and the damper portion is joined. In such a configuration, excessive tensile stress is applied to the damper portion due to stress applied during the manufacturing process of the liquid discharge head, making the damper portion prone to damage. On the other hand, if the damper portion is formed from a material with a lower coefficient of thermal expansion than the holding substrate, for example, the damper portion will be held by the holding substrate in such a way that compressive stress is generated in the damper surface direction after cooling following the joining of the holding substrate and the damper portion. In this configuration, the damper portion is in a relaxed state, so it is less likely to break even when stress is applied. However, buckling occurs in the damper portion due to its relaxed state. It has been found that if wavy buckling (buckling in which the direction of buckling (direction of deflection) differs depending on the location) occurs in the damper portion, the response to liquid pressure fluctuations deteriorates, and the damper function of the damper portion decreases. Therefore, in this embodiment, the damper portion is first held by the holding substrate so that compressive stress is generated in the direction of the damper surface, thereby suppressing damage to the damper portion. Furthermore, in this embodiment, the damper portion is configured such that the coefficient of linear expansion in the direction of the damper surface is asymmetric with respect to the center in the thickness direction. With this configuration, it is possible to control the damper portion to buckle in a way that causes it to bend to one side in the thickness direction across the entire damper surface. Consequently, according to this embodiment, the buckling that occurs in the damper portion is a buckling that causes it to bend to one side in the thickness direction across the entire damper surface, which allows for a continuous response to liquid pressure fluctuations and suppresses a decrease in the damper function of the damper portion compared to the case where the damper portion buckles in a wave-like manner.

[0090] [Second aspect] The second embodiment is characterized in that, in the first embodiment, the damper portion has a laminated structure in which a plurality of layers having different coefficients of thermal expansion are stacked in the thickness direction. According to this embodiment, it becomes easier to control the physical properties of the damper.

[0091] [Third aspect] The third embodiment is characterized in that, in the first or second embodiment, the damper portion is configured such that the coefficient of linear expansion increases in stages from one side in the thickness direction to the other side. According to this, it is possible to suppress the occurrence of abrupt stress changes in the damper section, making the damper section less likely to break.

[0092] [Fourth aspect] The fourth aspect is that, in any of the first to third aspects, the damper portion has an elastic compliance of 7 × 10 -17 Pa -1 The above is the characteristic feature. This makes it easier to set the optimal layer configuration for the damper's function.

[0093] [Fifth aspect] The fifth aspect is characterized in that, in any of the first to fourth aspects, the damper portion has a Young's modulus of 3 GPa or more and 200 GPa or less. This makes it easier to set the elastic compliance of the damper section within the preferred range mentioned above, and also allows for further suppression of liquid propagation.

[0094] [Sixth aspect] The sixth embodiment is characterized in that, in any of the first to fifth embodiments, the damper portion is formed by a layer made of a material selected from polysilicon, SiN, and SiO2. According to this, the damper section can be manufactured at a low cost.

[0095] [Seventh aspect] The seventh embodiment is characterized in that, in any of the first to sixth embodiments, the damper portion is held by a first retaining substrate which is an actuator substrate 102 equipped with an actuator member and a second retaining substrate which is a frame member 104 having a recess 141, and is joined to the second retaining substrate. This allows for a structure that can properly perform the damping function of the damper section.

[0096] [8th aspect] The eighth embodiment is a liquid dispensing unit characterized by comprising a liquid dispensing head according to any of the first to seventh embodiments. According to this embodiment, it is possible to provide a liquid discharge head that can suppress damage to the damper portion provided in the liquid discharge head and suppress deterioration of the damper function, thereby enabling the damper portion to fully perform its damping function.

[0097] [Ninth aspect] The ninth aspect is characterized in that, in the eighth aspect, the liquid discharge head is integrated with at least one of the following: a head tank for storing liquid supplied to the liquid discharge head, a carriage on which the liquid discharge head is mounted, a supply mechanism for supplying liquid to the liquid discharge head, a maintenance and recovery mechanism for maintaining and restoring the liquid discharge head, and a main scanning movement mechanism for moving the liquid discharge head in the main scanning direction. According to this embodiment, it is possible to provide a liquid discharge head that can suppress damage to the damper portion provided in the liquid discharge head and suppress deterioration of the damper function, thereby enabling the damper portion to fully perform its damping function.

[0098] [Tenth aspect] The tenth embodiment is a liquid dispensing device characterized by comprising a liquid dispensing head according to any of the first to seventh embodiments, or a liquid dispensing unit according to the eighth or ninth embodiment. According to this embodiment, it is possible to provide a liquid dispensing device that can achieve both suppression of damage to the damper portion provided in the liquid dispensing head and suppression of deterioration of the damper function, thereby allowing the damper portion to fully perform its damping function. [Explanation of Symbols]

[0099] 101: Nozzle substrate 102: Actuator board 103, 103', 103'': Damper section 104: Frame members 111: Nozzle 121: Common liquid chamber 122: Individual liquid chambers 123: Fluid resistance 124: Piezoelectric element 125: Vibration plate 126: Flow channel 127: Flow channel plate 131,131',131∆ damper 141: Recess 151: Adhesive 302: Polysilicon film 303,303':SiN film 304:HTO membrane [Prior art documents] [Patent Documents]

[0100] [Patent Document 1] Patent No. 4823714

Claims

1. A liquid discharge head that discharges liquid from a nozzle by varying the pressure in the pressure chamber using an actuator member, and attenuates the pressure fluctuations of the liquid by a damper held on a holding substrate, The liquid discharge head is characterized in that the damper portion has a lower coefficient of thermal expansion than the holding substrate, is configured to generate compressive stress in the damper surface direction perpendicular to the thickness direction, and has a coefficient of thermal expansion in the damper surface direction that is asymmetric with respect to the center in the thickness direction, causing buckling that causes bending to one side in the thickness direction.

2. In the liquid discharge head according to claim 1, The damper portion is characterized by a laminated structure in which multiple layers with different coefficients of linear expansion are stacked in the thickness direction.

3. In the liquid dispensing head according to claim 1 or 2, The liquid discharge head is characterized in that the damper portion is configured such that the coefficient of linear expansion increases in stages from one side to the other in the thickness direction.

4. In the liquid dispensing head according to any one of claims 1 to 3, The damper section has an elastic compliance of 7 × 10 －１７ Pa －１ A liquid dispensing head characterized by the above.

5. In the liquid dispensing head according to any one of claims 1 to 4, The damper portion is a liquid discharge head characterized by having a Young's modulus of 3 GPa or more and 200 GPa or less.

6. In the liquid dispensing head according to any one of claims 1 to 5, The damper portion is made of polysilicon, SiN, and SiO ２ A liquid dispensing head characterized by being formed by layers made of materials selected from the above.

7. In the liquid dispensing head according to any one of claims 1 to 6, The liquid discharge head is characterized in that the damper portion is held by a first holding substrate, which is an actuator substrate equipped with an actuator member, and a second holding substrate, which is a frame member having a recess, and is joined to the second holding substrate.

8. A liquid dispensing unit characterized by comprising a liquid dispensing head according to any one of claims 1 to 7.

9. In the liquid dispensing unit according to claim 8, A liquid discharge unit characterized by integrating a liquid discharge head with at least one of the following: a head tank for storing liquid to be supplied to the liquid discharge head; a carriage on which the liquid discharge head is mounted; a supply mechanism for supplying liquid to the liquid discharge head; a maintenance and recovery mechanism for maintaining and restoring the liquid discharge head; and a main scanning movement mechanism for moving the liquid discharge head in the main scanning direction.

10. A liquid dispensing device characterized by comprising a liquid dispensing head according to any one of claims 1 to 7, or a liquid dispensing unit according to claim 8 or 9.

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