Patent Application
20170259572
The present invention relates to a liquid ejection device, a method of manufacturing a liquid ejection device, and a printer.
A liquid ejection device (liquid ejection head) is configured to change liquid pressure in a region filled with liquid (pressure chamber) to eject liquid from a discharge port. A drop-on-demand liquid ejection device is most generally widespread. Further, systems for applying pressure to liquid are broadly divided into two systems. One of the systems is a system in which a capacity of the pressure chamber is changed by applying a drive signal to a piezoelectric element to displace the piezoelectric element, to thereby apply pressure to liquid. The other of the systems is a system in which a resistor produces heat by a drive signal applied to the resistor to generate an air bubble in the pressure chamber, to thereby apply pressure to liquid.
The liquid ejection device using the piezoelectric element can be manufactured relatively easily by mechanically processing a bulk piezoelectric material. Further, the liquid ejection device using the piezoelectric element is also advantageous in that there are few restrictions imposed on a kind of liquid and that liquid containing various materials can be ejected. From such a viewpoint, in recent years, there is an increase in attempts to use the liquid ejection device using the piezoelectric element for an industrial purpose such as manufacture of a color filter or formation of wiring.
Further, a technology involving changing a capacity of a pressure chamber (liquid channel) by displacing a partition formed of a piezoelectric material in a shear mode, to thereby eject liquid, can precisely control the capacity change of the pressure chamber, and thus has attracted great attention (see PTL 1).
Further, in recent years, there is a demand to eject a minute liquid droplet. For example, liquid ejection on the order of picoliters is required. Further, liquid ejection even on the order of subpicoliters or smaller is required.
However, it is not necessarily easy to eject a minute liquid droplet with stability.
It is an object of the present invention to provide a liquid ejection device capable of ejecting a minute liquid droplet with stability.
According to one aspect of an embodiment, a liquid ejection device, including: a base including: a first piezoelectric body; and a second piezoelectric body fixed to the first piezoelectric body and polarized in a direction opposite to a polarization direction of the first piezoelectric body; a pressure chamber formed to the base and separated by at least two partitions formed of the first piezoelectric body and the second piezoelectric body and by a plate mounted on end surfaces of the at least two partitions; and an electrode formed on both side surfaces of the at least two partitions, wherein: the pressure chamber is narrow on a front surface side on which a discharge port configured to eject liquid is formed; a surface of the at least two partitions that faces the pressure chamber includes: a first partition portion formed of only the first piezoelectric body; and a second partition portion formed of the first piezoelectric body and the second piezoelectric body; the pressure chamber is separated by the first partition portion on the front surface side; the pressure chamber is separated by the second partition portion on a back surface side on which a liquid chamber configured to supply the liquid to the pressure chamber is formed; the end surface of the first partition portion is fixed to the plate with a first adhesive layer; the end surface of the second partition portion is fixed to the plate with a second adhesive layer; and an elastic coefficient of the first adhesive layer is smaller than an elastic coefficient of the second adhesive layer.
According to another aspect of the embodiment, a liquid ejection device, including: a base including: a first piezoelectric body; and a second piezoelectric body fixed to the first piezoelectric body and polarized in a direction opposite to a polarization direction of the first piezoelectric body; a pressure chamber formed to the base and separated by at least two partitions formed of the first piezoelectric body and the second piezoelectric body and by a plate mounted on end surfaces of the at least two partitions; and an electrode formed on both side surfaces of the at least two partitions, wherein: the pressure chamber is narrow on a front surface side on which a discharge port configured to eject liquid is formed; a surface of the at least two partitions that faces the pressure chamber includes: a first partition portion formed of only the first piezoelectric body; and a second partition portion formed of the first piezoelectric body and the second piezoelectric body; the pressure chamber is separated by the first partition portion on the front surface side; the pressure chamber is separated by the second partition portion on a back surface side on which a liquid chamber configured to supply the liquid to the pressure chamber is formed; the end surface of the first partition portion is fixed to the plate with a first adhesive layer; the end surface of the second partition portion is fixed to the plate with a second adhesive layer; and a thickness of the first adhesive layer is larger than a thickness of the second adhesive layer.
According to further another aspect of the embodiment, a method of manufacturing a liquid ejection device, including: forming a groove in a first piezoelectric body and a second piezoelectric body fixed to the first piezoelectric body and polarized in a direction opposite to a polarization direction of the first piezoelectric body, to thereby form a pressure chamber separated by a partition including a first partition portion obtained by cutting up to the first piezoelectric body and a second partition portion obtained by cutting from the first piezoelectric body up to the second piezoelectric body; forming an electrode on the partition; and bonding a plate to the partition, wherein the bonding of the plate includes: bonding the plate to the first partition portion with a first adhesive; and bonding the plate to the second partition portion with a second adhesive.
According to further another aspect of the embodiment, a printer, including the above mentioned liquid ejection device.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
When a speed of a liquid droplet to be ejected becomes equal to or higher than a given speed, a minute liquid droplet separate from a main droplet (main liquid droplet) is unintentionally generated before the main droplet. Such a minute liquid droplet as to be generated separately from the main droplet is referred to as “satellite droplet”.
In general, in liquid ejection, the liquid is ejected while a liquid ejection device is being moved relatively to a target on which the liquid droplet is to land. Therefore, after a satellite droplet is generated, the satellite droplet lands in a position different from a landed position of the main droplet. The generation of the satellite droplet causes a pattern failure and the like.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
A liquid ejection device according to an embodiment of the present invention is described with reference to the drawings.
Note that, a case where a piezoelectric plate 12 is positioned on an upper side and a cover plate 11 is positioned on a lower side is illustrated in
As illustrated in
The piezoelectric plate 12 has a substantially flat plate shape. The piezoelectric plate 12 includes a piezoelectric member 12a and a piezoelectric member 12b fixed on the piezoelectric member 12a. More specifically, as illustrated in
As a material of the piezoelectric bodies 12a and 12b, for example, piezoelectric ceramics is used. As the piezoelectric ceramics, for example, a lead zirconate titanate (PZT: PbZrxTi1-XO3)-based ceramics material, which is a ferroelectric ceramics material, is used. Note that, as the piezoelectric ceramics for forming the piezoelectric bodies 12a and 12b, there may be used, for example, barium titanate (BaTiO3), or lanthanum-substituted lead zirconate titanate (PLZT: (Pb,La) (Zr,Ti)O3).
A plurality of grooves (openings) 1 and 2 are formed in the piezoelectric plate 12 so as to be in parallel with one another. A longitudinal direction of the grooves 1 and 2 is matched with a direction indicated by the arrow A of
The piezoelectric plate 12 includes partitions (piezoelectric partitions) 3 defined between the groove 1 and the groove 2. Each of the partitions 3 separates pressure chambers 1 and 2 formed in groove shapes from each other. The longitudinal direction of the partition 3 is matched with the arrow A of
On an end surface of the front surface side of the piezoelectric plate 12, that is, an end surface of the piezoelectric plate 12 on the side to which the orifice plate 60 is mounted, a groove 7 for forming an extracting pattern 23a (see
The cover plate (sometimes referred to simply as “plate”) 11 is mounted to an end surface (here referred to as “principal surface” (surface on the lower side of the drawing sheet of
The pressure chamber 1 and the pressure chamber 2 adjacent to the pressure chamber 1 are separated from each other by the same partition 3. Therefore, it is not necessarily easy to independently control a capacity of the pressure chamber 1 and a capacity of the pressure chamber 2 adjacent to the pressure chamber 1. Therefore, the pressure chamber 1 is used as a liquid channel, and the pressure chamber 2 adjacent to the pressure chamber 1 is used as a dummy.
The respective capacities of the pressure chambers 1 and 2 can also be controlled so that the pressure chamber 2 can also be used as the liquid channel. For example, an electrode 21b (see
Here, a case where the pressure chamber 2 is not used as the liquid channel is described as an example.
As illustrated in
On the other hand, in a region 19 on the back surface side of the piezoelectric transducer 10, the pressure chamber 1 is set to be relatively large (wide) in depth. Specifically, in the region 19 positioned on the other side of the pressure chamber 1 in the longitudinal direction A, the bottom of the pressure chamber 1 is positioned in a position deeper than the boundary between the piezoelectric member 12a and the piezoelectric member 12b. Therefore, in the region 19 on the back surface side of the piezoelectric plate 12, the partition 3 is formed of the piezoelectric member 12a and the piezoelectric member 12b. Specifically, in the region 19 on the back surface side of the piezoelectric plate 12, the partition 3 has a chevron structure. In this embodiment, a portion of a partition formed of the piezoelectric member 12b serving as the first piezoelectric member and the piezoelectric member 12a serving as a second piezoelectric member is referred to as “second partition portion”. Note that, in this specification, for the sake of convenience of description, the same reference numeral “19” is used for the region on the back surface side of the piezoelectric transducer 10, a region of the back surface side of the piezoelectric plate 12, and a region of a back surface side of the cover plate 11.
As illustrated in
The electrodes (drive electrodes) 21b are formed in the pressure chamber 1. The electrode 21b formed in the pressure chamber 1 is used for applying, in combination with the electrode 21a formed in the dummy chamber 2 to be described later, the partition (piezoelectric member) 3 with an electric field in a direction perpendicular to the polarization direction to displace the partition 3 in a shear mode. The electrodes 21b are formed on the side walls 25 of the partition 3 and a bottom surface of the groove 1. An upper end of the electrode 21b is matched with an upper end of the partition 3. Note that, as described above, for the sake of convenience of description, the description is made here on the assumption that the upper side of the drawing sheets of
The electrodes 21a are formed in the dummy chamber 2. The electrodes 21a are formed on the side walls 26 of the partition 3 and a bottom surface of the groove 2. An upper end of the electrode 21a is matched with the upper end of the partition 3.
As illustrated in
As illustrated in
It is preferred that the elastic coefficient of the first adhesive layer 57 be 10 MPa or more and 500 MPa or less.
It is preferred that the elastic coefficient of the second adhesive layer 58 be 500 MPa or more and 2,000 MPa or less.
The electrode 21a positioned on one side of the dummy chamber 2 and the electrode 21a positioned on the other side of the dummy chamber 2 are separated from each other by a separating groove 20 formed on a bottom surface of the dummy chamber 2. The separating groove is formed along the longitudinal direction (direction indicated by the arrow A) of the dummy chamber 2 so as to extend from one end of the groove 2 and reach the other end of the groove 2. Further, in the groove 7 formed on the front surface side of the piezoelectric plate 12, the separating groove 20 is connected to a separating groove 28 formed on one principal surface (surface on the upper side of the drawing sheet of
The pressure chamber 1 is formed so as to reach the end surface of the piezoelectric plate 12 on the back surface side, that is, the end surface of the piezoelectric plate 12 on the side to which the manifold 40 is mounted (see
On the other hand, the dummy chamber 2 is formed so as not to reach the end surface of the piezoelectric plate 12 on the back surface side, that is, the end surface of the piezoelectric plate 12 on the side to which the manifold 40 is mounted. With this, the liquid is prevented from being supplied from the manifold 40 into the dummy chamber 2.
The manifold 40 is mounted to the back surface side of the piezoelectric transducer 10. A common liquid chamber 43 (see
The orifice plate 60 is mounted on the front surface (surface on a liquid ejecting side) side of the piezoelectric transducer 10. The orifice plate 60 is formed of, for example, plastic. Nozzles (discharge ports) 60a are formed in the orifice plate 60 at positions corresponding to those of the pressure chambers (liquid channels) 1. The nozzles 60a are arrayed in the direction indicated by the arrow B of
As illustrated in
As illustrated in
Next, a method of applying a voltage to the each electrode of the liquid ejection device according to this embodiment is described with reference to the drawings.
As illustrated in
As illustrated in
As illustrated in
The extracting electrodes 4a1, 4a2, and 4a3 are electrically connected to the respective signal lines formed on the flexible substrate 50 (
Therefore, when a voltage Va is applied to any one of the plurality of signal lines 51 formed on the flexible substrate 50 (
Further, in the same manner, when a voltage Vb is applied to any one of the plurality of signal lines 51 formed on the flexible substrate 50 (
Next, displacement of the partition of the piezoelectric transducer of the liquid ejection device according to this embodiment is described with reference to
A case where the potential Va of the electrode 21a within the dummy chamber 2 is equal to the potential Vb of the electrode 21b within the pressure chamber 1, that is, a case where Va=Vb, is illustrated in
A case where the potential Va of the electrode 21a within the dummy chamber 2 is higher than the potential Vb of the electrode 21b within the pressure chamber 1, that is, a case where Va>Vb, is illustrated in
As illustrated in
As illustrated in
A case where the potential Va of the electrode 21a within the dummy chamber 2 is lower than the potential Vb of the electrode 21b within the pressure chamber 1, that is, a case where Va<Vb, is illustrated in
In the region 18 on the front surface side of the piezoelectric transducer 10, as illustrated in
In the region 19 on the back surface side of the piezoelectric transducer 10, as illustrated in
Next, an operation of the liquid ejection device according to this embodiment is described with reference to
A case where the potential Va of the electrode 21a within the dummy chamber 2 is equal to the potential Vb of the electrode 21b within the pressure chamber 1, that is, a case where Va=Vb, is illustrated in
In this embodiment, in the case of
Further, it is possible to eject liquid with stability at a desired ejection speed by appropriately setting the displacement amount of the partition 3 in the region 18 on the front surface side of the piezoelectric transducer 10 and the displacement amount of the partition 3 in the region 19 on the back surface side of the piezoelectric transducer 10.
In this way, according to this embodiment, in the region 19 on the back surface side of the piezoelectric transducer 10, the bottom surface of the pressure chamber 1 is positioned in the position deeper than the boundary between the piezoelectric member 12a and the piezoelectric member 12b. On the other hand, in the region 18 on the front surface side of the piezoelectric transducer 10, the bottom surface of the pressure chamber 1 is positioned in the position shallower than the boundary between the piezoelectric member 12a and the piezoelectric member 12b. Further, on the front surface side of the piezoelectric transducer 10, the upper surface of the partition 3 is fixed to the cover plate 11 with the adhesive layer 57 having a relatively low elastic coefficient. Therefore, according to this embodiment, in the region 18 on the front surface side of the piezoelectric transducer 10, the partition 3 can be displaced with reliability. Accordingly, when the pressure chamber is contracted in the region 19 on the back surface side of the piezoelectric transducer 10, the pressure chamber can be expanded in the region on the front surface side of the piezoelectric transducer. Therefore, according to this embodiment, when the liquid droplet is ejected by contracting the region 19 on the back surface side of the piezoelectric transducer 10, it is possible to alleviate the sudden concentration of pressure into a nozzle, which can inhibit a satellite droplet from being generated. Accordingly, according to this embodiment, it is possible to provide a liquid ejection device capable of ejecting a minute liquid droplet with stability.
Next, a method of manufacturing a liquid ejection device according to this embodiment is described with reference to
First, two piezoelectric substrates (piezoelectric bodies) 12a and 12b having opposite polarization directions are bonded together by use of the adhesive layer 16 (see
Subsequently, a surface of the piezoelectric member 12b is subjected to cutting (grinding) so that the thickness of the piezoelectric member 12b becomes a desired thickness. In this way, the piezoelectric plate 12 in which the piezoelectric member 12b having a desired thickness is arranged on the piezoelectric member 12a is obtained (see
Subsequently, as illustrated in
Specifically, the plurality of grooves 1 are formed so as to be in parallel with one another. In the forming of the grooves 1, only the piezoelectric member 12b is processed in the region 18 on the front surface side (front side of the drawing sheet of
Then, the grooves 2 for forming the dummy chambers are formed in the piezoelectric plate 12 by use of the diamond blade (not shown). As a dicing apparatus, for example, a dicing apparatus similar to the dicing apparatus used in forming the grooves 1 can be used. The grooves 2 are formed so as to be along the longitudinal direction of the grooves 1. The plurality of grooves 2 are formed so as to be in parallel with one another. Regions in which the grooves 2 are to be formed are set so that the plurality of grooves 2 are at the centers between the plurality of grooves 1 formed so as to be in parallel with one another, respectively. The grooves 2 are formed so as not to reach the end surface of the piezoelectric plate 12 on the back surface side. This is for the purpose of preventing liquid from being supplied from the manifold 40 into the dummy chambers 2. In the region 19 on the back surface side of the piezoelectric plate 12, the depth of the grooves 2 is, for example, the same as that of the grooves 1. Note that, the depth of the grooves 2 is not required to be the same as that of the grooves 1. For example, the depth of the grooves 2 may be appropriately set in a range of from 1 to 1.15 times as much as the depth of the grooves 1. A portion between the groove 1 and the groove 2 serves as the partition 3. The partition 3 is positioned on both sides of the pressure chamber formed by the groove 1.
Then, the grooves 7 are formed in the end surface of the piezoelectric plate 12 on the front surface side by use of the diamond blade (not shown). The grooves 7 are formed so as to extend in the direction of the normal to the principal surface of the piezoelectric plate 12. The grooves 7 are formed for the purpose of forming the extracting patterns 23a extracted from the electrodes 21a. Processing conditions in forming the grooves 7 are, for example, similar to processing conditions in forming the grooves 2. The grooves 7 are formed on the front surface side of the piezoelectric plate 12, that is, on the front side of the drawing sheet of
Note that, the case of the processing using the diamond blade is described here as an example, but the present invention is not limited thereto. A processing tool capable of performing the processing so as to keep the piezoelectric plate 12 below a Curie temperature can be appropriately used. For example, the piezoelectric plate 12 may be processed by use of an end mill or the like.
Then, as illustrated in
First, by etching the surface of the piezoelectric plate 12, minute depressions (unevenness) are formed in the surface of the piezoelectric plate 12. Then, deleading treatment for removing from the surface of the piezoelectric plate 12 lead (Pb) contained in the material of the piezoelectric plate 12 is applied.
Next, as described below, a plated catalyst is deposited onto the surface of the piezoelectric plate 12. For example, tin (Sn) and palladium (Pd) are used as the plated catalyst. In this case, the deposition is described by way of the case where the plated catalyst of palladium is generated. First, the piezoelectric plate 12 is immersed into an aqueous solution of stannous chloride with a concentration of about 0.1%, thereby depositing stannous chloride onto the surface of the piezoelectric plate 12. Subsequently, the piezoelectric plate 12 is immersed into an aqueous solution of palladium chloride with a concentration of about 0.1%, thereby allowing an oxidation-reduction reaction between tin chloride, which is deposited onto the piezoelectric plate 12 in advance, and palladium chloride to occur to generate metallic palladium on the surface of the piezoelectric plate 12. Thus, the plated catalyst of metallic palladium is deposited onto the surface of the piezoelectric plate 12.
Next, the piezoelectric plate 12 in which metallic palladium is generated on its surface is immersed into, for example, a nickel plating bath, thereby forming an electroless plating film containing nickel (Ni) on the surface of the piezoelectric plate 12. For example, the following films are formed as the electroless plating film: an electroless plating film of nickel-phosphorus (Ni—P) and an electroless plating film of nickel-boron (Ni—B). It is preferred that a thickness of the electroless plating film be set to be about 0.5 μm to 1.0 μm for the purpose of sufficiently cover the surface of the piezoelectric plate 12 and sufficiently reducing electrical resistance. In this way, the electroless plating film is formed on the entire surface of the piezoelectric plate 12.
After that, for example, through replacement plating, a gold (Au) plating film, for example, is formed on the electroless plating film. In this way, the conductive film 55 including the plating film is formed on the entire surface of the piezoelectric plate 12.
Then, unnecessary portions of the conductive film formed on the entire surface of the piezoelectric plate 12 are removed (see
Portions of the conductive film 55 on one principal surface (surface on the upper side of the drawing sheet of
Further, the separating groove 20 is formed at the bottom of the groove 2 to serve as the dummy chamber, and the separating groove 28 is formed at the bottom of the groove 7 for the extracting electrode. The separating grooves 20 and 28 are for the purpose of separating the electrode 21a positioned on one side of the grooves 2 and 7 and the electrode 21a positioned on the other side of the grooves 2 and 7 from each other. When the separating grooves 20 and 28 are formed, for example, the diamond blade can be used. The separating grooves 20 and 28 each have a width of, for example, about ½ to ⅓ of the width of the groove 2 or 7. Note that, the width of the separating grooves 20 and 28 is not limited thereto, and may be appropriately set. The separating groove 20 is formed along the longitudinal direction of the groove 2 so as to extend from a front end of the groove 2 to reach a rear end thereof. Further, the separating groove 28 is formed along the longitudinal direction of the groove 7 so as to extend from an upper end of the groove 7 to reach a lower end thereof. The electrode 21a positioned on one side of the groove 2 or 7 and the electrode 21a positioned on the other side of the groove 2 or 7 are separated from each other, and thus, different signal voltages can be applied to those electrodes 21a. Therefore, the partitions 3 of the pressure chambers 1 can be individually displaced.
Then, as illustrated in
Note that, the case where the adhesive layer 57 is applied on the piezoelectric plate 12 side and the adhesive layer 58 is applied on the cover plate 11 side is described here as an example, but the present invention is not limited thereto. The adhesive layer 57 may be applied on the cover plate 11 side, and the adhesive layer 58 may be applied on the piezoelectric plate 12 side.
The adhesive layers 57 and 58 can be directly applied on the piezoelectric plate 12 and the cover plate 11 by, for example, a screen printing method, a bar coating method, or an offset printing method. Further, after the adhesive layers 57 and 58 are applied on different substrates such as glass substrates by use of at least of one of those application methods, the adhesive layers 57 and 58 applied on the different substrates may be transferred onto the piezoelectric plate 12 and the cover plate 11.
Subsequently, the front surface side, the back surface side, and the like of the piezoelectric plate 12 are subjected to grinding, polishing, and the like, to thereby remove the conductive film 55 from the piezoelectric plate 12 and adjust the external shape and dimensions.
Subsequently, the separating groove (not shown) is appropriately formed in one principal surface (surface on the upper side of the drawing sheet of
After that, the manifold 40 is mounted on the back surface side of the piezoelectric transducer 10 (see
Further, the orifice plate 60 is mounted on the front surface side of the piezoelectric plate 12 (see
Further, the flexible substrate 50 is mounted to one principal surface (surface on the upper side of the drawing sheet of
In this way, the liquid ejection device according to this embodiment is manufactured.
Next, a liquid ejection device according to a modification example of this embodiment is described with reference to
As illustrated in
In this modification example, in the region 18 on the front surface side of the piezoelectric transducer 10, the adhesive layer 15 is formed to be relatively thick, and hence the adhesive layer 15 is likely to deform so as to follow the displacement of the partition 3. Therefore, in the region 18 on the front surface side of the piezoelectric transducer 10, even though the electrodes 21a and 21b cover all the side walls 25 and 26 of the partition 3, the partition 3 can be sufficiently displaced.
In this way, in the region 18 on the front surface side of the piezoelectric transducer 10, the adhesive layer 15 may also be formed to be relatively thick.
Next, an operation of the liquid ejection device according to this modification example is described.
In the case where the potential Va of the electrode 21a within the dummy chamber 2 is equal to the potential Vb of the electrode 21b within the pressure chamber 1, that is, in the case where Va=Vb, the liquid ejection device according to this modification example also conducts the same operation as the operation of the liquid ejection device according to the embodiment described above with reference to
In the case where the potential Va of the electrode 21a within the dummy chamber 2 is higher than the potential Vb of the electrode 21b within the pressure chamber 1, that is, in the case where Va>Vb, the liquid ejection device according to this modification example also conducts the same operation as the operation of the liquid ejection device according to the embodiment described above with reference to
In the case where the potential Va of the electrode 21a within the dummy chamber 2 is lower than the potential Vb of the electrode 21b within the pressure chamber 1, that is, in the case where Va<Vb, the liquid ejection device according to this modification example also conducts the same operation as the operation of the liquid ejection device according to the embodiment described above with reference to
Next, a method of manufacturing a liquid ejection device according to this modification example is described with reference to
From a step of forming the piezoelectric plate 12 to a step of forming the separating grooves 20 and 28 are the same as those of the method of manufacturing a liquid ejection device described above with reference to
Subsequently, as illustrated in
In other words, a plate is prepared, in which a recess is formed so that the portion to be opposed to the first partition portion is retracted from the portion to be opposed to the second partition portion.
Subsequently, the adhesive layer 15 is applied on the cover plate 11 in which the recess 70 is formed. In this case, the adhesive layer 15 is formed so that the upper surface of the adhesive layer 15 in the region 18 on the front surface side of the cover plate is matched in level with the upper surface of the adhesive layer 15 in the region 19 on the back surface side (side to which the manifold 40 is mounted) of the cover plate 11. As described above, the recess 70 is formed in the region on the front surface side of the cover plate 11. Therefore, the thickness of the adhesive layer 15 in the region on the front surface side of the cover plate 11 is larger than the thickness of the adhesive layer 15 in the region on the back surface side of the cover plate 11 by the depth D of the recess 70.
Note that, a method of forming the adhesive layer 15 is not limited thereto.
For example, the adhesive layer 15 may be formed in the following manner. Specifically, first, the adhesive layer 15 is applied on an entire surface of the cover plate 11 so as to fill an inside of the recess 70 of the cover plate 11. After that, the adhesive layer 15 is cured. After that, the adhesive layer 15 is polished until the surface of the cover plate 11 is exposed in the region 19 on the back surface side of the cover plate 11. This causes the recess 70 of the cover plate 11 to be filled with the adhesive layer 15. After that, the adhesive layer 15 is further applied on the cover plate 11. Even when the adhesive layer 15 is thus formed, the thickness of the adhesive layer 15 in the region on the front surface side of the piezoelectric transducer 10 becomes larger than the thickness of the adhesive layer 15 in the region on the back surface side of the piezoelectric transducer 10.
Further, the adhesive layer 15 may be formed in the following manner. Specifically, first, the adhesive layer 15 is applied on the entire surface of the cover plate 11 so as to fill the inside of the recess 70 of the cover plate 11. After that, the adhesive layer 15 is cured. After that, the adhesive layer 15 is polished until the surface of the cover plate 11 is exposed in the region 19 on the back surface side of the cover plate 11. This causes the recess 70 of the cover plate 11 to be filled with the adhesive layer 15. On the other hand, the adhesive layer 15 is applied also on the piezoelectric plate 12 side. Specifically, the adhesive layer 15 is applied on the upper surface of the partition 3 of the piezoelectric plate 12. After that, the cover plate 11 and the piezoelectric plate 12 are aligned to be joined to each other. Even when the adhesive layer 15 is thus formed, the thickness of the adhesive layer 15 in the region 18 on the front surface side of the piezoelectric transducer 10 becomes larger than the thickness of the adhesive layer 15 in the region 19 on the back surface side of the piezoelectric transducer 10.
In the same manner as in the method of manufacturing a liquid ejection device according to the embodiment described above with reference to
The subsequent steps of the method of manufacturing a liquid ejection device are the same as those of the method of manufacturing a liquid ejection device described above with reference to
Note that, the present invention is not limited to the above-mentioned embodiment. Changes can be made thereto appropriately by a person who has common knowledge in this technical field within the scope that does not depart from the technical thought of the present invention.
Further, in the above-mentioned embodiment, the inkjet head to be used for a printer or the like is described as an example of the liquid ejection device, but the present invention is not limited thereto. For example, the liquid ejection device may be a liquid ejection device configured to eject liquid containing metal fine particles. When the liquid containing metal fine particles is ejected, it is possible to form metal wiring (metal pattern) or the like. Further, the liquid ejection device may be a liquid ejection device configured to eject resist liquid (resist ink). When the resist liquid is ejected, it is possible to form a resist pattern.
Next, more specific examples of the present invention are described.
First, Example 1 is described with reference to
In Example 1, the groove 1 was formed by being subjected to processing using the diamond blade. Therefore, in Example 1, the pressure chamber 1 was set to partially have a tapered shape. In Example 1, a flat portion 61 that is a part having a flat bottom surface of the pressure chamber 1 was formed in the region 18 on the front surface side (left side of the drawing sheet of
In Example 1, a dimension L of the pressure chamber 1 in the longitudinal direction, that is, a length L of the pressure chamber 1 was set to 8 mm. Further, in Example 1, a length L1 of the flat portion 61 in the region 18 on the front surface side of the piezoelectric transducer 10 was set to 0.5 mm. Further, in Example 1, a length L2 of the partial tapered portion 62 in the region 18 on the front surface side of the piezoelectric transducer 10 was set to 1.1 mm. Further, in Example 1, a length L3 of the partial tapered portion 63 in the region 19 on the back surface side of the piezoelectric transducer 10 was set to 2.8 mm. Further, in Example 1, a length L4 of the flat portion 64 in the region 19 on the back surface side of the piezoelectric transducer 10 was set to 3.6 mm.
The direction indicated by the arrow C of
Further, in Example 1, a dimension W1 of the partition 3 in a direction indicated by an arrow B of
As illustrated in
On the other hand, in the region 19 on the back surface side of the piezoelectric transducer 10, the cover plate 11 and the piezoelectric plate 12 were joined to each other with the adhesive layer 58. As the adhesive layer 58, a one-pack epoxy resin (product number: B-1077B) manufactured by TESK CO., LTD. was used. The elastic coefficient of the adhesive layer 58 was 1,000 MPa.
A thickness t1 of each of the adhesive layers 57 and 58 was set to 2 μm.
After that, the manifold 40, the orifice plate 60, the flexible substrate 50, and the like were mounted, to obtain the liquid ejection device according to Example 1.
The liquid ejection device according to Example 1 was evaluated by being caused to eject liquid. As the liquid to be ejected in the evaluation, an ethylene glycol solution diluted with water was used. A density of ethylene glycol within the liquid was set to 80 wt %. When the liquid was ejected from the liquid ejection device according to Example 1, voltages to be applied to the electrodes 21a and 21b were set as follows. That is, the electrode 21b has a potential of 0 V. On the other hand, a pulse-like signal having a positive voltage was applied to the electrode 21a. The signal to be applied to the electrode 21a was set to have a pulse width of 8 μs. An imaging apparatus to which a microscope was attached was used to pick up an image of a liquid droplet in a flying state. As a light source used for picking up the image of the liquid droplet in the flying state, a light source configured to emit nanopulse laser light was used.
As the voltage of the pulse-like signal to be applied to the electrode 21a was increased, the speed of the liquid droplet increased. When the speed of the liquid droplet (main droplet) became equal to or larger than a given speed, a minute liquid droplet (satellite droplet) separate from the main droplet was generated before the main droplet. When the satellite droplet began to be generated, the speed of the main droplet differed depending on a diameter of the nozzle 60a. The speed of the main droplet exhibited when the satellite droplet began to be generated is shown in Table 1.
In Comparative Example 1, the same adhesive layer 58 is used to join the piezoelectric plate 12 and the cover plate 11 to each other both in the region 19 on the back surface side of the piezoelectric transducer 10 and in the region 18 on the front surface side of the piezoelectric transducer 10. In Comparative Example 1, as the adhesive layer 58, the one-pack epoxy resin (product number: B-1077B) manufactured by TESK CO., LTD. was used. In Comparative Example 1, the elastic coefficient of the adhesive layer 58 was 1,000 MPa. In Comparative Example 1, the thickness of the adhesive layer 58 was set to 2 μm.
As can be seen from Table 1, in Comparative Example 1, when the diameter of the nozzle 60a was set to be relatively small, the satellite droplet was generated even with a relatively low speed of the liquid droplet.
In contrast, in Example 1, even when the diameter of the nozzle 60a was relatively small and when the speed of the liquid droplet was relatively high, the satellite droplet was hardly generated.
In Comparative Example 1, it is conceivable that, when the diameter of the nozzle 60a is set to be relatively small, the satellite droplet is generated even when the speed of the liquid droplet is relatively low for the following reason. Specifically, in Comparative Example 1, also in the region 18 on the front surface side of the piezoelectric transducer 10, the partition 3 is fixed to the cover plate 11 with the adhesive layer 58 having a relatively high elastic coefficient. Therefore, in Comparative Example 1, in the region 18 on the front surface side of the piezoelectric transducer 10, the partition 3 is hardly displaced. Therefore, in Comparative Example 1, when the partial pressure chamber 1a (see
In Example 1, in the region 18 on the front surface side of the piezoelectric transducer 10, the partition 3 is fixed to the cover plate 11 by use of the adhesive layer 57 having a relatively low elastic coefficient, and hence the partition 3 can be displaced in the region 18 on the front surface side of the piezoelectric transducer 10. Therefore, in Example 1, when the partial pressure chamber 1a is contracted in the region 19 on the back surface side of the piezoelectric transducer 10, the partial pressure chamber 1b is expanded in the region 18 on the front surface side of the piezoelectric transducer 10. Therefore, according to Example 1, when the partial pressure chamber 1a is contracted in the region 19 on the back surface side of the piezoelectric transducer 10, it is possible to alleviate the concentration of the pressure of the liquid into the nozzle 60a. Therefore, according to Example 1, even when the diameter of the nozzle 60a is set to be relatively small and when the speed of the liquid droplet is set to be relatively high, it is possible to prevent the satellite droplet from being easily generated.
Next, Example 2 is described with reference to
Example 2 corresponds to the liquid ejection device according to the modification example of the embodiment described above with reference to
In
A thickness t2 of the adhesive layer 15 in the region 19 on the back surface side of the piezoelectric transducer 10, that is, the thickness t2 of the adhesive layer 15a was set to 2 μm.
A thickness t3 of the adhesive layer 15 in the region 18 on the front surface side of the piezoelectric transducer 10, that is, the thickness t3 of the adhesive layer 15b was set to 12 μm.
The depth D of the recess 70 in the cover plate 11 was set to 10 μm.
As the adhesive layer 15, that is, as the adhesive layers 15a and 15b, the one-pack epoxy resin (product number: B-1077B) manufactured by TESK CO., LTD. was used. The elastic coefficient of the adhesive layer 15 was 1,000 MPa.
The thus-obtained liquid ejection device according to Example 2 was evaluated in the same manner as in Example 1. The speed of the main droplet exhibited when the satellite droplet began to be generated in the liquid ejection device according to Example 2 is shown in Table 2.
As can be seen from a comparison between Table 1 and Table 2, also in Example 2, substantially the same performance as in Example 1 is obtained.
It is conceivable that the results of evaluation of Example 2 is substantially the same as the results of evaluation of Example 1 because the partition 3 can be displaced also in Example 2 in the same manner as in Example 1 in the region 18 on the front surface side of the piezoelectric transducer 10.
Next, Example 3 is described with reference to
Example 3 corresponds to the liquid ejection device according to the modification example of the embodiment described above with reference to
The adhesive layer 15b to be used in the region on the front surface side of the piezoelectric transducer 10 was selected from three kinds of adhesive having different elastic moduli E1. As the adhesive layer 15b having an elastic modulus E1 of 1,000 MPa, the one-pack epoxy resin (product number: B-1077B) manufactured by TESK CO., LTD. was used. As the adhesive layer 15b having an elastic modulus E1 of 200 MPa, the one-pack epoxy resin (product number: EF-328) manufactured by Sanyu Rec Co., Ltd. was used. As the adhesive layer 15b having an elastic modulus E1 of 20 MPa, the one-pack epoxy resin (product number: EF-288) manufactured by Sanyu Rec Co., Ltd. was used.
As the adhesive layer 15a to be used in the region 19 on the back surface side of the piezoelectric transducer 10, an adhesive having an elastic modulus E2 of 1,000 MPa was used. As the adhesive layer 15a, the one-pack epoxy resin (product number: B-1077B) manufactured by TESK CO., LTD. was used.
The diameter of the nozzle 60a was set to φ10 μm.
A ratio of the elastic modulus E1 to the thickness t3 of the adhesive layer 15b used in the region 18 on the front surface side of the piezoelectric transducer 10 is set as r1. The ratio r1 is expressed by the following expression. r1=E1/t3
A ratio of the elastic modulus E2 to the thickness t2 of the adhesive layer 15a used in the region 19 on the back surface side of the piezoelectric transducer 10 is set as r2. The ratio r2 is expressed by the following expression. r2=E2/t2
The ratio r1 indicates a degree of rigidity of the adhesive layer 15b, and the ratio r2 indicates a degree of rigidity of the adhesive layer 15a. As the value of r1 becomes smaller, the rigidity of the adhesive layer 15b becomes smaller, and the value of r2 becomes smaller, the rigidity of the adhesive layer 15a becomes smaller.
The speed of the main droplet exhibited when the satellite droplet began to be generated in the liquid ejection device according to Example 3 is shown in Table 3.
As can be seen from Table 3, as the ratio (r2/r1) of r2 to r1 became larger, the speed of the main droplet exhibited when the satellite droplet began to be generated became higher.
However, when the ratio (r2/r1) of r2 to r1 exceeded 500, the liquid droplet was not ejected stably. This is because influence of residual vibration of the partition 3 in the region 18 on the front surface side of the piezoelectric transducer 10 cannot be ignored when the rigidity of the adhesive layer 15b in the region 18 on the front surface side of the piezoelectric transducer 10 becomes too small.
In view of the above-mentioned observation, it is preferred that the ratio (r2/r1) of r2 to r1 be 5 or more and 500 or less.
According to the present invention, in the region on the back surface side of the piezoelectric transducer, the bottom surface of the pressure chamber is positioned in the position deeper than the boundary between the first piezoelectric member and the second piezoelectric member. On the other hand, in the region on the front surface side of the piezoelectric transducer, the bottom surface of the pressure chamber is positioned in the position shallower than the boundary between the first piezoelectric member and the second piezoelectric member. Further, on the front surface side of the piezoelectric transducer, the upper surface of the partition is fixed to the cover plate with the adhesive layer having a relatively low elastic coefficient or the relatively thick adhesive layer. Therefore, according to the present invention, in the region on the front surface side of the piezoelectric transducer, the partition can be displaced with reliability. Accordingly, when the pressure chamber is contracted in the region on the back surface side of the piezoelectric transducer, the pressure chamber can be expanded in the region on the front surface side of the piezoelectric transducer. Therefore, according to the present invention, when the liquid droplet is ejected by contracting the region on the back surface side of the piezoelectric transducer, it is possible to alleviate the sudden concentration of pressure into the nozzle, which can inhibit the satellite droplet from being generated. Consequently, according to the present invention, it is possible to provide the liquid ejection device capable of ejecting a minute liquid droplet with stability.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-184814, filed Sep. 11, 2014 which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2014-184814 | Sep 2014 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2015/004589 | 9/9/2015 | WO | 00 |
