Patent Grant
9636914
This application claims priority under 35 U.S.C. §119 from Japanese Patent Applications No. 2014-169365 filed on Aug. 22, 2014. The entire subject matter of the application is incorporated herein by reference.
Technical Field
The present disclosures relate to a liquid ejecting device and a method of manufacturing a liquid ejecting device.
Related Art
Conventionally, a liquid ejecting device has been known. An example of such a liquid ejecting device is employed in an inkjet head of an inkjet printer configured to eject ink drops through nozzles formed on the inkjet head. Typically, the inkjet head has a nozzle plate made of synthetic resin (hereinafter, occasionally referred to as plastic) and formed with multiple nozzles, a passage-formed plate made of metal and formed with inflow passages communicating with the multiple nozzles, and piezoelectric elements provided to the passage-formed plate. Such an inkjet head is configured such that the piezoelectric elements apply pressures to ink existing in the ink flow passages to eject the ink drops through the nozzles.
In the inkjet head as described above, typically, an ink-repellent coat is formed on an ink ejection surface, which is a surface of the nozzle plate and formed with the multiple ink ejection openings, of the plastic nozzle plate at portions surrounding ejection openings of the multiple nozzles in order to prevent the ink resides around the multiple nozzles. Further, according to a conventional inkjet head, two lines of elongated protrusions, which extend in a direction of a nozzle array, are formed on the ink ejection surface of the nozzle plate with each nozzle array arranged therebetween. With the protrusions, when a printing sheet is lifted due to sheet jam or the like during a printing operation, the printing sheet is prevented or suppressed from contacting the ejection openings as it contacts the protrusions. Thus, with this configuration, a peripheral part of each ejection opening or the ink-repellent coat around each ejection opening is prevented from being damaged by the printing sheet.
The conventional nozzle plate as described above is typically manufactured in accordance with a manufacturing process as follows. As a substrate made of synthetic resin which serves as the nozzle plate, a synthetic-resin film made of polyimide or the like is prepared. On one surface of the synthetic-resin film, an ink-repellent agent is applied, and heated-air drying is applied to form the ink-repellent coat. Then, on the synthetic-resin film formed with the ink-repellent coat, multiple nozzles are formed by laser beam machining. Next, the synthetic-resin film formed with the multiple nozzles is bonded with the passage-formed plate formed with passage holes. After bonding, a metal mold is placed on the ink ejection surface of the nozzle plate, on which the ink-repellent coat is formed, and heat-press is applied, the protruded parts are formed on the ink ejection surface.
In the conventional art as described above, the protruded parts are formed on the nozzle plate. Accordingly, the protruded parts are formed of the synthetic-resin. Since the synthetic-resin is low, the protruded parts have low endurance. As the printing sheet repeatedly hits, the protruded parts may be whittled gradually and finally they may be disappear. If the printing sheet hits the protruded parts with a relatively strong force, a part of the protruded part may be chipped.
Further, the protruded parts are typically formed to the plastic substrate, which is to be used as the nozzle plate, by the heat press procedure, due to the heat applied thereto during the heat press procedure, the substrate may warp at the time of the heat press procedure. In order to suppress the degree of the warp, it becomes difficult to apply a relatively large deformation to the substrate, which results in relatively low protruded parts. When the height of the protruded parts is low, the printing sheet may contact the ejection openings easily, and thus, protecting effect of the protruded parts is lowered.
In consideration of the above, according to aspects of the disclosures, an improved liquid ejecting device is provided. With the improved liquid ejecting device, protruded parts are formed in the vicinity of the ejection openings so that portions surrounding the ejection openings can be well protected from being hit by the printing sheet. Further, the protruded parts exhibit high endurance.
According to aspects of the disclosures, there is provided a liquid ejecting device, having a fluid passage structure formed with multiple nozzles arranged in a particular nozzle arrangement direction and multiple passages respectively communicating with the multiple nozzles. The fluid passage structure has a metallic nozzle plate formed with the multiple nozzles which is arranged in a nozzle arrangement direction. Further, the metallic nozzle plate has a liquid ejection surface on which multiple ejection openings respectively corresponding to the multiple nozzles being formed, multiple convex parts protruding from the liquid ejection surface, the multiple convex parts being arranged along the nozzle arrangement direction, beside the multiple ejection openings, respectively. Further, the multiple convex parts are formed by press working applied to the nozzle plate from a side opposite to the liquid ejection surface.
According to aspects of the disclosures, there is provided a method of manufacturing liquid ejecting device having a fluid passage structure formed with multiple nozzles arranged in a particular nozzle arrangement direction and multiple passages respectively communicating with the multiple nozzles. The fluid passage structure has a metallic plate on which the multiple nozzles which is arranged in a nozzle arrangement direction are to be formed. Further, the metallic plate has a liquid ejection surface on which multiple ejection openings respectively corresponding to the multiple nozzles to be formed, and the method includes a convex part forming process of forming multiple convex parts protruding from the liquid ejection surface, the multiple convex parts being arranged along the nozzle arrangement direction, beside the multiple ejection openings, respectively. Further, the multiple convex parts are formed by press working applied to the metallic plate from a side opposite to the liquid ejection surface.
Referring to the accompanying drawings, an illustrative embodiment and its modifications will be described. In the embodiments, an invention of a liquid ejecting device will be applied to an inkjet head.
As shown in
A printing sheet 100 on which an image will be printed is to be placed on an upper surface of the platen 2. The carriage 3 is configured to reciprocally move along a pair of guide rails 10 and 11, in a scanning direction, within an range in which the carriage 3 faces the platen 2. The carriage 3 is connected with an endless belt 14. When a carriage drive motor 15 moves the endless belt 14, the carriage 3 moves in the scanning direction. Such a configuration is well-known, and will not be described in detail anymore.
The inkjet head 4 is attached to the carriage 3 and is movable, together with the carriage 3, in the scanning direction. On a lower surface, which is a farther side with respect to the plane of
The conveying mechanism 5 has two conveying rollers 18 and 19, which are arranged on opposite sides, in a conveying direction, with respect to the platen 2 such that the conveying rollers 18 and 19 sandwich the platen 2 therebetween in the conveying direction. The conveying mechanism 5 conveys the printing sheet 100 placed on the platen 2 with the two conveying rollers 18 and 19.
As movement of the inkjet head 4 in the scanning direction and ejection of the ink drops from the multiple nozzles 44, and conveying of the printing sheet 100 in the conveying direction by a particular amount with use of the conveying rollers 18 and 19 are executed alternately, an image and/or characters are printed on the printing sheet 100.
The maintenance mechanism 6 is arranged on a right side with respect to the platen within a movable range of the carriage 3 in the scanning direction. The maintenance mechanism 6 has a cap 20, a suction pump 21 connected to the cap 20, and a wiper 22.
The cap 20 is configured to move in the up-down direction (i.e., in a direction orthogonal to the plane of
The wiper 22 is a thin plate member made of elastic material such as rubber, and arranged next to the cap 20 in the scanning direction. Immediately after the suction purge is executed, ink is adhered on the lower surface of the inkjet head. According to the illustrative embodiment, after the suction purge is executed, the carriage 3 is moved in the scanning direction with the cap 20 spaced from the lower surface of the inkjet head 4. During this movement of the inkjet head 4, the wiper 22 keeps contacting the lower surface of the inkjet head 4 and moves relative to the loser surface of the inkjet head 4 so that the ink adhered onto the lower surface of the inkjet head 4 is wiped off.
As shown in
As shown in
The lowermost plate 39 is a nozzle plate on which the multiple nozzles 44 are formed. Each of the nozzles 44 is a through-opening piercing through the plate 39, the through-opening has a tapered cylindrical shape of which a lower side (i.e., an ink ejection side) has a smaller diameter. In the following description, the lower surface of the nozzle plate 39 on which the ejection openings 44a are formed will occasionally be referred to as an ink ejection surface 39a (see
The multiple nozzles 44 are arranged in four lines, each line extending in the conveying direction, and the four lines are arranged in the scanning direction. In the following description, the each line of the nozzles 44 will be referred to a nozzle array. As shown in
The ink ejection surface 39a of the nozzle plate 39 is covered with a liquid-repellent coat 40 made of fluorine resin such as PTFE (polytetrafluoroethylene). As the liquid-repellent coat 40 covers the ink ejection surface 39a at a surrounding area of each of the ejection openings 44a, the ink ejected by the nozzles 44 are prevented from residing on portions surrounding the ink ejection openings 44. It is noted that, although the liquid-repellent coat 50 is formed on an entire area of the lower surface of the nozzle plate 39, such a configuration can be modified so that only surrounding areas of the ejection openings 44a of the ink ejection surface 39a are covered with the liquid-repellent coat 40.
On the plates 31-38 except for the nozzle plate 39, the ink flow passages including manifolds 46 and pressure chambers 47 (described below) are formed.
As shown in
Further, on the fourth to seventh plates 34-47 from the top, four manifolds 46k, 46y, 46c and 46m are formed. It is noted that each of or all of the four manifolds 46k, 46y, 46c and 46m will occasionally be referred to collectively as manifolds 46. According to the illustrative embodiment, each manifold 46 is formed through the four laminated plates 34-37. The four ink supply holes 45 are connected to the four manifolds 46, respectively, through communication holes (not shown) formed on the plates 32 and 33.
On the lowermost plate 37 of the four plates 34-37 forming the manifolds 46, four concave parts 37b extending along the four manifolds 46 are formed by half etching, at portions serving as a bottom wall parts 37a that partition the four manifolds 46 as shown in
Further, on an upper surface of the plate 38 which is located immediately below the plate 37, concave parts 38b are formed by half etching at portions facing the bottom wall parts 37a. The portions of the plate 38 facing the bottom wall parts 37a are formed to be thin-walled parts 38a having smaller thickness than the other parts of the plate 38. Furthermore, spaces 41 are formed between the bottom wall parts 37a of the manifolds 46 formed on the plate 37 and the thin-walled parts 38a formed below the bottom wall parts 37a, respectively. With this configuration, in accordance with pressure change inside the manifolds 46, the bottom wall parts 37a easily deform so that the pressure changes inside the manifolds 46 are reduced by deformation of the bottom wall parts 37a.
On the uppermost plate 31, multiple pressure chambers 44 respectively corresponding to the multiple nozzles 44 are formed. The multiple pressure chambers 47 are arranged to have four lines corresponding to the four manifolds 46. The multiple pressure chambers 47 are covered with a vibration plate 60 of the piezoelectric actuator 24. As shown in
As shown in
The plates 31-39 described above are laminated and bonded to constitute the passage unit 23. Inside the passage unit 23, from one manifold 46, multiple individual passages are diverged to reach the multiple nozzles 44 via the throttle passage 49, the pressure chamber 47 and the communication passages 43.
In a conventional inkjet head, there could be a situation where the printing sheet being conveyed in the conveying direction contacts the ink ejection surface of the inkjet head when the printing sheet is jammed or conveyed as it is in a bent state. In such a case, an end part of the ejection opening or a surrounding area of the ejection opening may be scratched by the printing sheet, which may cause an ejection failure in an ink ejection direction or the like. In particular, when the ink ejection surface is covered with the liquid-repellent coat, scratching of the liquid-repellent coat around the ink ejection opening may lower liquid-repellency, which may result in residual ink around the ink ejection opening and ejection failure of the ink drops.
According to the illustrative embodiment, multiple convex parts 50 are formed on the ink ejection surface 39a, as shown in
As shown in
As described above, on the nozzle plate 39, the four nozzle arrays 48 (48k, 48y, 48c and 48m) respectively configured to eject black, yellow, cyan and magenta ink are arranged in the scanning direction. Then, as shown in
On both sides, in the scanning direction, of the nozzle array 48k, two lines 51a and 51b of the convex parts 50 are arranged so that the two lines 51a and 51b sandwiches the nozzle array 48k. The three lines 51b, 51c and 51d of the convex parts 50 are arranged between each two of the four nozzle arrays 48 (48k, 48y, 48c and 48m). With this arrangement, each of the four nozzle arrays 48 (48k, 48y, 48c and 48m) is sandwiched, in the scanning direction, by two lines 51 of the convex parts 50.
As described above, the multiple convex parts 50 are arranged along the nozzle arrangement direction (i.e., the conveying direction), and next, in the scanning direction, to the multiple nozzles 44. Further, each nozzle array 48 is sandwiched between two lines 51 of the convex parts 50 arranged at closer positions in the scanning direction. With this configuration, regardless whether the carriage 3 moves leftward or rightward, the printing sheet 100 will not contact the surrounding areas of the nozzles 44 so easily. Thus, it is ensured that the surrounding area of the ejection opening 44a of each nozzle 44 is protected by the convex parts 50 arranged closer to the ejection opening 44a, and the liquid-repellent coat 40 is prevented from being scratched or damaged.
As shown in
As is know from
As described above, the convex parts 50 which protrude from the ink ejection surface 39a are formed by deforming parts of the nozzle plate 39 which is made of metallic material. As the convex parts 50 are formed by the metallic material, strength of each convex parts 50 is high, and the convex parts 50 are excellent in durability. That is, even if the printing sheet 100 hits the convex part 50, the convex part 50 will not be lost as whittled or hipped by the printing sheet 100.
As shown in
The multiple individual electrodes 62 are respectively connected to driver ICs (integrated circuits) 67, which are configured to control the piezoelectric actuator 24. The common electrode 66 is always kept to have a grounded electric potential. Further, portions of the upper piezoelectric layer 65 sandwiched between the individual electrodes 62 and the common electrode 66 are polarized in its thickness direction, respectively.
An operation of the piezoelectric actuator 24 when the ink drops are ejected from the nozzles 44 will be described. When a drive signal is applied from the driver IC 67 to a certain individual electrode 62, a potential difference is generated between the individual electrode 66 and the common electrode which is maintained to have the ground potential. Then, in a portion of the piezoelectric layer 65 at a portion sandwiched by the individual electrode 62 and the common electrode 66, an electrical field is generated in its thickness direction.
Since the polarization direction of the piezoelectric layer 65 and the direction of the electric field coincide with each other, the piezoelectric layer 65 extend in the thickness direction, which is the polarization direction, and shrinks in a surface direction. In association with this deformation (i.e., extension and shrink) of the piezoelectric layer 65, a portion of the vibration plate 60 facing the pressure chamber 47 warps to protrude toward the pressure chamber 47. At this stage, a capacity of the pressure chamber 47 is reduced and a pressure is applied to the ink inside the pressure chamber 47, thereby an ink drop is ejected through the nozzle 44 communicating with the pressure chamber 47.
Next, a method of manufacturing the inkjet head 4 described above will be described centering on a manufacturing process of the passage unit 23.
Firstly, on the metallic plates constituting the passage unit 23 except for the nozzle plate 39 (i.e., the plates 31-38), openings and holes constituting parts of the ink flow passages such as the pressure chambers 47, the manifolds 46 and individual passage holes 32c-38c are formed by etching.
Next, as shown in
Next, as shown in
Next, as shown in
Next, as shown in
As shown in
In a general press working, a stripper is provided to a surface of a work on which the punch is press-contacted in order to ensure that the punch is removed from the work after the press working and/or to prevent the warp of the work. When a foreign body is engaged between the work and the stripper, an indentation may be formed. According to the above-described illustrative embodiment, the punch 73 can easily be removed, after processing, from the nozzle plate 39 since only the tapered part 39a is pushed in with respect to the nozzle plate 39. Further, the warp of the nozzle plate 39 caused by the press working is relatively small. Therefore, according to the illustrative embodiment, the processing can be executed without using the stripper 80. Therefore, in order to prevent the occurrence of the indentation on the nozzle plate 39, it is preferable not to provide the stripper 80.
As described above, according to the illustrative embodiment, the multiple convex parts 50 protruded from the ink ejection surface 39a of the nozzle plate 39 are formed by the press working performed for the surface opposite to the ink ejection surface 39a. Further, it is possible to form the convex parts 50 which are largely protruded from the ink ejection surface 39a at areas relatively close to the nozzles 44 by largely deforming the metallic nozzle plate 39 by the press working. Furthermore, since the nozzle plate 39 is made of metallic material, plastic deformation of the metallic material is occurred by the press working, the shape of the convex parts 50 is maintained after the press working.
It is noted that the nozzle plate 39 is a metallic rolled member produced by the rolling process. Generally, the rolled member has an anisotropic property in its material structure since the rolled member is extended in its rolling direction, and the crystal grains are also extended in the rolling direction. Therefore, when the punch 73 is press-contacted on the metallic nozzle plate 39 and the convex part 50 is formed, deformation in the crystal grain boundary occurs easier in a direction orthogonal to the rolling direction than in the rolling direction. As a result, the deformation area is smaller in the direction orthogonal to the rolling direction. Thus, even though the cylindrical punch 73 is used, the convex part 50 formed on the nozzle plate 39 has an oval shape which is longer in the rolling direction as shown in
When the convex part 50 and the nozzle 44 are arranged in the rolling direction, when the metallic member constituting the nozzle plate 39 is expanded in the rolling direction when the convex part 50 is formed by the press working, there is a possibility that a portion of the nozzle plate 30 at which the nozzle 44 is formed is also deformed and the shape of the nozzle nay be changed or position of the nozzle may be changed. Therefore, it is preferable that the arrangement direction of the nozzles 44 (i.e., the conveying direction) is along the rolling direction of the nozzle plate 39. With such a configuration, the lines of the nozzles 44 (i.e., the nozzle arrays) and the lines of the convex parts 50 are aligned with the direction orthogonal to the rolling direction of the nozzle plate 39. Accordingly, when the press working is performed, even though the nozzle plate 39 deforms largely in the rolling direction, affection thereof to the portions of the nozzle plate 39 where the nozzles 44 are formed is small.
Regarding a relationship between the rolling direction and the convex parts 50, the following should also be noted. According to the illustrative embodiment, the multiple convex parts 50 are arranged in the two directions: the conveying direction (nozzle arrangement direction); and the scanning direction. Further, as shown in
In the above description, an example in which the number of the convex parts 50 arranged in the conveying direction is larger than that in the scanning direction is described. However, when the number of the convex parts 50 arranged in the scanning direction is larger than that in the conveying direction, the scanning direction is aligned to the rolling direction of the nozzle plate 39. Further, regarding the other plates 31-38 which also constitute the passage unit 23, by laminating the same such that the rolling direction of each of the metallic plates 31-38 coincides with the rolling direction of the nozzle plates 39, the warp suppressing effect in the nozzle plate 39 can be increased.
After the multiple nozzles 44 are formed on the nozzle plate 39, the protective film 71 is removed from the nozzle plate 39 as shown in
Next, the nozzle plate 39 on which the multiple convex parts 50 and the multiple nozzles 44 are formed, the other plates 31-38 constituting the passage unit 23, and the vibration plate 60 of the piezoelectric actuator 24 are bonded. According to the illustrative embodiment, as shown in
It is noted that the inkjet head 4 is an example of a liquid ejecting device in claims. The passage unit 23 is an example of a passage structure in the claims. The ink ejection surface 39a, which is the lower surface of the nozzle plate 39 is an example a liquid ejection surface in the claims. Further, the metallic plate 70 on which the multiple nozzles 44 are formed is an example of a metallic plate in the claims.
Hereinafter, modified embodiments which are modifications of the above-described illustrative embodiment will be described. In the following description on the modified embodiments, components and/or structures similar to those in the above-described embodiment are assigned with the same reference numbers and description thereof will be omitted for brevity.
1) The shape of the convex part 50 does not need to be limited to that of the illustrative embodiment described above. By changing the shape of the tip of the punch 73 and/or the die 72, the convex part 50 may have various shapes. Further, depending on characteristic of material of the plate 38 (e.g., ductility and the like), the deformation direction of the convex part 50 may not slant in a particular direction of the nozzle plate 39. In such a case, when the punch 73 having the cylindrical shape is used, the convex part 50 may have a substantially circular shape when viewed from the above.
2) Positions of the convex parts 50 on the nozzle plate do not need to be limited to those of the illustrative embodiment. According to the illustrative embodiment shown in
According to another modification shown in
3) The nozzle plate 39 may be configured to have thin parts at which the thickness of the nozzle plate 39 is partially decreased, and the convex parts 50 are formed by applying the press working to the think parts. Such a configuration will be further described referring to
In a modification shown in
That is, as shown in
The convex parts 50 of the nozzle plate 39 is formed by the press working at the thin parts 39c. By applying the press working to the thin parts 39c, deformation of the nozzle plate 39 by the press working will not expand outward exceeding a boundary between the thin part 39c and portion thicker than the thin part 39c. Accordingly, an area in which the deformation expands is restricted. Therefore, affection of deformation of the thin-walled parts 38a at the time of press working to portions where the nozzles 44 are formed is suppressed. It is noted that, in the modification shown in
In the configuration shown in
As a further modification of the configuration shown in
4) According to the illustrative embodiment, as shown in
5) The inkjet head 4 according to the illustrative embodiment is a so-called serial type head, which is configured to eject the ink drops as it moves together with the carriage 3 with respect to the printing sheet 100. It is noted that the aspects of the disclosure does not need to be limited to the serial head. For example, the configuration according to the illustrative embodiment may be applied to a line type head which is fixedly provided inside a main body of the printer and is configured such that multiple nozzles are arranged in a width direction of the printing sheet 100.
The illustrative embodiment and its modifications described above are directed to the inkjet printer which ejects the ink drops to print an image and the like on the printing sheet. It is noted that the above configuration may also be applied to a liquid ejecting device which is used in other purposes other than printing of images. For example, the above-described configuration may be applied to a liquid ejecting device configured to eject conductive liquid onto a circuit substrate to form a conductive pattern on the surface of the circuit substrate.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-169365 | Aug 2014 | JP | national |
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| Number | Date | Country | |
|---|---|---|---|
| 20160052271 A1 | Feb 2016 | US |
