This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2019-163933, filed on Sep. 9, 2019, the entire contents of which are incorporated herein by reference.
Embodiments described herein generally relate to a liquid discharge head and a liquid discharge recording apparatus.
A liquid discharge head used in various liquid discharge recording apparatuses, which utilizes densely-arranged nozzles to achieve reduction of head size and increase in an image resolution, is known. In such a liquid discharge head, when the volume of a pressure chamber is changed, causing liquid droplets to eject from the densely-arranged nozzles, a pressure wave is generated and propagates to other pressure chambers such as adjacent or nearby pressure chambers through a common flow path in the liquid discharge head, and the ejection of liquid droplets from the nozzles in the other pressure chambers may be affected.
Hence, there is a need for a liquid discharge head and a liquid discharge recording apparatus that is capable of suppressing the influence on other pressure chambers when a liquid droplet is ejected from a nozzle via another nearby or adjacent pressure chamber.
In one embodiment, a liquid discharge head comprises a substrate, a nozzle plate, and a damper member. The substrate comprises a plurality of pressure chambers. The nozzle plate is provided on a first surface of the substrate and comprises a plurality of nozzles. Each of the plurality of nozzles faces is aligned with a corresponding one of the plurality of pressure chambers. The damper member is on a second surface of the substrate and comprises a pressure wave absorbing material. Portions of the damper member are on the second surface at positions between adjacent pressure chambers generated in the pressure chamber.
Hereinafter, a liquid discharge head 1 and a liquid discharge recording apparatus 100 according to a first embodiment will be described with reference to
As shown in
As shown in
In the present embodiment, the substrate 21 is formed in a rectangular plate shape. On one main surface (hereinafter referred to as a first surface) of the substrate 21, the nozzle plate 22 is integrally fixed. On the opposite main surface (hereinafter referred to as a second surface) of the substrate 21, the liquid supply unit 12 is integrally fixed. The substrate 21 has a plurality of pressure chambers 21a formed therein.
Each pressure chamber 21a is, for example, a cylindrical through hole formed in the substrate 21. Openings of the pressure chamber 21a at its one end and another end are covered by the nozzle plate 22 and the liquid supply unit 12, respectively. The plurality of pressure chambers 21a are arranged in an array in row and column directions.
As shown in
Each of the plurality of nozzles 31 is a through hole formed in the nozzle plate 22. Each nozzle 31 is formed, for example, in a cylindrical shape or a truncated cone shape. As shown in
As shown in
As shown in
The damper member 23 is provided on the second surface of the substrate 21. Portions of the damper member 23 are disposed on the second surface of the substrate 21 at positions between adjacent pressure chambers 21a and outside the outermost pressure chambers 21a. The damper member 23 is, for example, formed in a rectangular plate shape that is smaller in planar dimension than that of the substrate 21, as shown in
The damper member 23 is formed of an elastically deformable material. The damper member 23 is formed of a material different from that of the substrate 21. In one embodiment, the damper member 23 is formed of a material having a reflectance R of 0.5≤R≤2 when a specific acoustic impedance of the damper member 23 is represented by Z1, a specific acoustic impedance of the liquid supplied in the pressure chamber is represented by Z2, and the reflectance R=(Z2−Z1)/(Z1+Z2) is satisfied.
The damper member 23 includes, for example, a plurality of damper chambers 23a provided corresponding to the pressure chambers 21a. Each damper chamber 23a is, for example, a cylindrical opening having the same inner diameter as that of the pressure chamber 21a. The plurality of damper chambers 23a are arranged in the damper member 23 in an array of rows and columns in a similar manner to the plurality of pressure chambers 21a.
The liquid supply unit 12 covers the second surface of the substrate 21 and the damper member 23. The liquid supply unit 12 forms a common liquid chamber 41 between the second surface of the substrate 21 and the damper member 23. In addition, the liquid supply unit 12 includes a suction port 42 and a discharge port 43.
The common liquid chamber 41 forms a flow path. The common liquid chamber 41 is fluidly connected with the pressure chambers 21a through the damper chambers 23a. The suction port 42 is provided on a first side of the common liquid chamber 41. The discharge port 43 is provided on a second side of the common liquid chamber 41.
The drive signal supply unit 13 includes, for example, a flexible substrate 51 and a driver IC 52. One end of the flexible substrate 51 is connected to the wiring electrodes 33a and the shared electrodes 33b. The driver IC 52 is connected to the wiring electrodes 33a via, for example, the flexible substrate 51.
In the liquid discharge head 1 according to the first embodiment, portions of the damper member 23 are disposed on the second surface of the substrate 21 between adjacent pressure chambers 21a. When the driving element 32 is driven to cause liquid droplets to eject from a nozzle 31 corresponding to a particular pressure chamber (hereinafter referred to as a first pressure chamber) among the plurality of the pressure chambers 21a and a residual pressure wave in the first pressure chamber 21a propagates to the liquid in the damper chamber 23a facing the first pressure chamber 21a (hereinafter referred to as a first damper chamber), the damper member 23 can absorb or mitigate the propagating pressure wave. Further, the pressure wave transmitted to the common liquid chamber 41 through the first damper chamber 23a is attenuated in the common liquid chamber 41. In addition, the pressure wave propagated to an adjacent or nearby damper chamber 23a (hereinafter referred to as a second damper chamber) by crosstalk is also absorbed by the damper member 23.
Accordingly, the liquid discharge head 1 can absorb the pressure wave (or pressure waves) generated by an ejection of droplets from a nozzle (or nozzles) 31 and suppress the crosstalk by inclusion of the damper member 23, and it is thus possible to prevent the pressure wave generated when the droplets are ejected from the nozzle 31 of the first pressure chamber 21a from propagating to an adjacent or nearby pressure chamber 21a. Therefore, the liquid discharge head 1 according to the present embodiment can suppress fluctuations in the speed and volume of the liquid ejection and can eject the liquid droplets from the nozzles 31 with high accuracy.
Since the damper member 23 is formed of a material having a reflectance R of 0.5≤R≤2 according to one embodiment, the damper member 23 can further effectively absorb the pressure waves generated in the pressure chambers 21a.
As described above, according to the liquid discharge head 1 of the first embodiment, the damper member 23 capable of absorbing the pressure waves is provided, and thus it is possible to suppress influences on neighboring pressure chambers 21a when the liquid droplets are ejected from a nozzle 31.
Next, a liquid discharge recording apparatus 100 equipped with the liquid discharge head 1 will be described with reference to
The liquid discharge recording apparatus 100 is an ink jet printer that performs an image forming process on a sheet of paper P by discharging a liquid, such as ink, while moving the sheet of paper P, along a predetermined conveyance path A1 extending from the recording medium supply unit 112 through the image forming unit 113 to the recording medium ejection unit 114. In this context, the sheet of paper P can be referred to as a recording medium. In other examples, the recording medium may, in general, be any object on to which an image or information can be transferred via image forming unit 113.
The recording medium supply unit 112 comprises a plurality of sheet feeding cassettes 112a. The recording medium ejection unit 114 includes an ejection tray 114a. The image forming unit 113 comprises a support portion 117 that supports sheets and a plurality of head units 130 disposed above the support portions 117.
The support portion 117 includes a conveyance belt 118 provided in a loop shape and there is a predetermined region/position utilized for forming an image, a support plate 119 configured to support the conveyance belt 118 from the back side, and a plurality of belt rollers 120 provided on the back side of the conveyance belt 118.
The head unit 130 comprises: a plurality of liquid discharge heads 1; a plurality of supply tanks 132, which are liquid tanks mounted on each liquid discharge head 1, a plurality of connection flow paths 133, each configured to connect a corresponding one of the liquid discharge heads 1 with a corresponding one of the supply tanks 132; and a plurality of circulation pumps 134, each configured to serve as a circulation unit. The head unit 130 in this example is a circulating head unit type through which circulates liquid ink.
In the present embodiment, liquid discharge heads 1C, 1M, 1Y, and 1K, respectively for cyan, magenta, yellow, and black, are provided as the liquid discharge heads 1 and supply tanks 132C, 132M, 132Y, and 132K are respectively provided for containing the inks of the respective colors. These supply tanks 132 are connected to the liquid discharge heads 1 by the corresponding connection flow paths 133. Each connection flow path 133 includes a supply flow path 133a connected to the suction port 42 of the liquid discharge head 1 and a collection flow path 133b connected to the discharge port 43 of the liquid discharge head 1.
A negative pressure control device such as a pump is also connected to the supply tank 132 according to one embodiment. The ink supplied to each nozzle of a liquid discharge head 1 is formed into a meniscus having a predetermined shape by controlling the negative pressure in the supply tank 132 with the negative pressure control device according to the hydrostatic head value of the liquid discharge head 1 and the supply tank 132.
Each circulation pump 134 is, for example, a liquid feeding pump configured by a piezoelectric pump. The circulation pump 134 is provided in the supply flow path 133a. The circulation pump 134 is connected to the controller 116 by a wire. The circulation pump 134 is controlled by the controller 116. The circulation pump 134 circulates the liquid in a circulation flow path including the liquid discharge head 1 and the supply tank 132.
The conveyance device 115 conveys a sheet of paper P along the conveyance path A1 extending from the sheet feeding cassette 112a of the recording medium supply unit 112 through the image forming unit 113 to the media ejection tray 114a of the recording medium discharge unit 114. The conveyance device 115 includes a plurality of guide plate pairs 121a to 121h disposed along the conveyance path A1 and a plurality of conveyance rollers 122a to 122h. The conveyance device 115 supports the sheet of paper P to be movable relative to the liquid discharge head 1. That is, the conveyance device 115 moves the sheet of paper P past the liquid discharge head 1 during printing of the like.
The controller 116 includes a central processing unit (CPU) 116a as an example of a processor, a read only memory (ROM) that stores various programs and the like, a random access memory (RAM) that temporarily stores various types of variable data and image data, and an interface that receives data from the outside and outputs data to the outside. The processor performs various operations on data or the like based on programs stored in the memory. By executing a program stored in the memory, the processor functions as a control unit or controller that is capable of executing various operations according to program instructions.
In the liquid discharge recording apparatus 100 equipped with the liquid discharge head 1 according to the present embodiment, during the operation of the liquid discharge from the nozzle (or nozzles) 31 (hereinafter also referred to as a target nozzle), the controller 116 applies a driving voltage to the driving element 32 corresponding to the target nozzle 31 by the driver IC 52. For example, the controller 116 drives the driving element 32, deforms the periphery of the target nozzle 31 in a direction in which the volume of the pressure chamber 21a aligned with the target nozzle 31 increases, and causes the pressure chamber 21a to have a negative pressure, thereby guiding the ink into the pressure chamber 21a. Subsequently, the controller 116 drives the driving element 32, deforms the periphery of the target nozzle 31 in a direction in which the volume of the pressure chamber 21a increases, and pressurizes the inside of the pressure chamber 21a, thereby ejecting the droplets from the target nozzle 31.
By using the liquid discharge head 1 equipped with the damper member 23, the liquid discharge recording apparatus 100 according to the present embodiment can suppress fluctuations in the speed and volume of the liquid ejection from the nozzles 31 and can eject the liquid droplets with high accuracy. Thus, the liquid discharge recording apparatus 100 is capable of printing on a sheet of paper P with high accuracy.
Next, a liquid discharge head 1 according to a second embodiment will be described with reference to
The liquid discharge head 1 according to the second embodiment includes a liquid discharge unit 11A, a liquid supply unit 12, and a drive signal supply unit 13 (see
Portions of the damper member 23A are provided on the second surface of the substrate 21 at positions between adjacent pressure chambers 21a. The damper member 23A is formed in a rectangular plate shape having a planar dimension smaller than the substrate 21, as shown in
In the liquid discharge head 1 having the liquid discharge unit 11A according to the second embodiment, as with the liquid discharge head 1 according to the first embodiment, by integrating therein the damper member 23A capable of absorbing a pressure wave, it is possible to suppress influences on neighboring or nearby pressure chambers 21a when the liquid droplets are ejected from one or more first nozzles 31. Each damper chamber 23a is an opening with a diameter larger than that of the pressure chamber 21a. The damper chamber 23a of this configuration prevents the obstruction of a smooth liquid flow from the common liquid chamber 41 to the pressure chamber 21a.
Next, a liquid discharge head 1 according to a third embodiment will be described with reference to
The liquid discharge head 1 according to the third embodiment includes a liquid discharge unit 11B, a liquid supply unit 12, and a drive signal supply unit 13 (see
Portions of the damper member 23B are provided on the second surface of the substrate 21 at positions between adjacent pressure chambers 21a. The damper member 23B is formed in a rectangular plate shape having a planar dimension smaller than that of the substrate 21, as shown in
In the liquid discharge head 1 having the liquid discharge unit 11B according to the third embodiment, as with the liquid discharge head 1 according to the first embodiment, by integrating therein the damper member 23B capable of absorbing a pressure wave, it is possible to suppress influences on neighboring or nearby pressure chambers 21a when the liquid droplets are ejected from one or more first nozzles 31. Further, since each damper chamber 23a of the damper member 23B is an opening with a smaller diameter than that of the pressure chamber 21a, the thickness of the damper member 23B between the adjacent pressure chambers 21a is larger than that of damper member 23 in the first embodiment. Therefore, the liquid discharge head 1 can further absorb the pressure wave by the damper member 23B as compared with the first embodiment.
Next, a liquid discharge head 1 according to a fourth embodiment will be described with reference to
The liquid discharge head 1 according to the fourth embodiment includes a liquid discharge unit 11C, a liquid supply unit 12, and a drive signal supply unit 13 (see
Portions of the damper member 23C are provided on the second surface of the substrate 21 at positions between adjacent pressure chambers 21a. The damper member 23C is, for example, formed in a rectangular plate shape having a planar dimension that is smaller than the substrate 21. In this example, the damper member 23C has the same size as the opening area of the common liquid chamber 41, as shown in
In a similar manner to the liquid discharge head 1 according to the first embodiment, the liquid discharge head 1 having the liquid discharge unit 11C equipped with the damper member 23C capable of absorbing the pressure wave according to the fourth embodiment, can suppress influences of the liquid droplet ejection from the nozzles 31 on the pressure chambers 21a.
Further, since each of the damper chambers 23a of the damper member 23C is constituted by the plurality of through holes 23b that each have a smaller diameter than that of the corresponding pressure chamber 21a, the damper member 23B can further absorb the pressure waves as compared with the first embodiment. Also, since each damper chamber 23a includes several through holes 23b, the opening area of the damper chamber 23a can still be provided as much as possible, and restriction, if any, of the liquid flow from the common liquid chamber 41 into the pressure chamber 21a can be limited.
In the present embodiment, the damper member 23C may be formed to have the same size as the size of the common liquid chamber 41 in the flow direction of the liquid, that is, the same size as the opening area of the opening along the liquid flow direction in the common liquid chamber 41. This configuration can prevent undesirable steps from being formed in the flow direction of the common liquid chamber 41. Therefore, the damper member 23C can suppress disturbance of the flow in the common liquid chamber 41. Note that the configuration in which the damper member is formed to have the same size as that of the common liquid chamber 41 in the liquid flow direction may be applied to other embodiments.
Next, a liquid discharge head 1 according to a fifth embodiment will be described with reference to
The liquid discharge head 1 according to the fifth embodiment includes a liquid discharge unit 11D, a liquid supply unit 12, and a drive signal supply unit 13 (see
The first damper member 23 has the same configuration as that of the damper member 23 of the liquid discharge unit 11 according to the first embodiment, for example.
The second damper member 24 is provided in the common liquid chamber 41. The second damper member 24 has a main surface facing towards the plurality of pressure chambers 21a and the plurality of damper chambers 23a. The second damper member 24 is, for example, hollow and is formed in a film-like material that is elastically deformable or at least has flexibility in a portion facing towards the damper member 23. The second damper member 24 is formed of, for example, the same material as that of the first damper member 23.
According to the liquid discharge head 1 having the liquid discharge unit 11D according to the fifth embodiment, similarly to the liquid discharge head 1 according to the first embodiment, the absorption of the pressure wave generated by the ejection of the droplets and the suppression of the crosstalk can be performed by the first damper member 23, and the pressure wave generated when the liquid droplets are discharged from the nozzles 31 can be suppressed from propagating to adjacent pressure chambers 21a.
In addition, the pressure waves propagated from the damper chambers 23a to the common liquid chamber 41 are absorbed by the second damper member 24. Therefore, the pressure waves transmitted to the common liquid chamber 41 through the damper chambers 23a are attenuated by the second damper member 24. Accordingly, the propagation of the pressure waves generated in the pressure chambers 21a to the adjacent or nearby damper chambers 23a and pressure chambers 21a by the crosstalk can be effectively suppressed. Note that the second damper member 24 may be applied in combination with the other embodiments (first embodiment through fourth embodiment).
Next, a liquid discharge head 1 according to a sixth embodiment will be described with reference to
The liquid discharge head 1 according to the sixth embodiment includes a liquid discharge unit 11E, a liquid supply unit 12, and a drive signal supply unit 13 (see
The damper walls 25 are provided on the second surface of the substrate 21. As shown in
The damper wall 25 is formed of a material that can be elastically deformed. The damper wall 25 is formed of a material different from that of the substrate 21. As a specific example, the damper wall 25 is formed of a material having a reflectance R of 0.5≤R≤2 when the specific acoustic impedance is represented by Z1, the specific acoustic impedance of the liquid supplied into the pressure chamber is represented by Z2, and the reflectance R is represented by (Z2−Z1)/(Z1+Z2).
In the liquid discharge head 1 according to the sixth embodiment as described above, the discrete damper walls 25 are provided between the adjacent pressure chambers 21a rather than a damper member 23. Therefore, the liquid discharge head 1 can absorb the pressure wave generated by the jet of droplets and suppress the crosstalk. The damper walls 25 are partitions positioned between adjacent pressure chambers 21a. Furthermore, the adjacent damper walls 25 are spaced apart from each other. Therefore, while the damper walls 25 are positioned to limit crosstalk, they do not substantially inhibit the flow of the liquid from the common liquid chamber 41 into the pressure chamber 21a.
In the embodiments described above, each of the damper members 23, 23A, 23B, 23C, 23D, 23E, and 24 is formed of a material having a reflectance R of 0.5≤R≤2; however, the present disclosure is not limited to these embodiments. For example, the damper members 23, 23A, 23B, 23C, 23D, 23E, and 24 may be formed of material having a Young's modulus less than that of the substrate 21. Furthermore, the damper members 23, 23A, 23B, 23C, 23D, 23E, and 24 may be formed of a material having a Young's modulus less than that of the substrate 21 and having a reflectance R of 0.5≤R≤2, for example.
The liquid to be ejected is not limited to the ink for printing. For example, a device for ejecting a liquid containing conductive particles for forming a wiring pattern of a printed wiring board may be applicable.
While in the embodiments described above, the liquid discharge head is applied to a liquid discharge recording apparatus, such as an inkjet recording apparatus, its application is not limited thereto. For example, the liquid discharge head can be used for a 3D printer, an industrial manufacturing machine, a medical device application, and the like, and it is still possible to obtain the advantages of the example embodiments, such as improvements in printing quality and/or a reduction in size, weight, or cost of such other apparatus types.
According to the liquid discharge head or the liquid discharge recording apparatus of the embodiments described above, influences of the droplet ejection from the nozzles on neighboring or nearby pressure chambers can be effectively suppressed.
While certain embodiments have been described, these embodiments have been presented by way of example only and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
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