Patent Application
20140217198
1. Field of the Invention
The present invention relates to a liquid discharge apparatus in which individual liquid chambers partitioned by partitions made by a piezoelectric material are formed, and a manufacturing method of the liquid discharge apparatus.
2. Description of the Related Art
Conventionally, as a liquid discharge apparatus, a liquid discharge head which emits droplets by changing pressure of ink in an individual liquid chamber to generate a flow of the ink, and thus discharging the ink from a nozzle has been popularized. In particular, a drop-on-demand head has been most popularized. Here, there are roughly two methods of applying the pressure to the ink, that is, one is the method of changing the pressure to the ink by changing the pressure in the individual liquid chamber in response to a driving signal supplied to a piezoelectric element, and the other is the method of applying the pressure to the ink by generating bubbles in the individual liquid chamber in response to a driving signal supplied to a resistor.
The liquid discharge head in which the piezoelectric element is used can be manufactured with comparative ease by machine-processing a bulk piezoelectric material. Moreover, the liquid discharge head of this type has an advantage that restriction of ink is comparatively small and thus inks of wide-range materials can be selectively applied to a recording medium. Based on this point of view, in recent years, an attempt to utilize the liquid discharge head for industrial applications such as manufacture of color filters, formation of wirings and the like is often made.
In this context, in the piezoelectrically-actuated liquid discharge heads to be industrially utilized, a shear mode method is often adopted. In the shear mode method, a phenomenon that a polarized piezoelectric material is shear-deformed when an electric field is applied thereto in its orthogonal direction is utilized. Here, the piezoelectric material to be deformed corresponds to a partition which is formed by processing and making an ink groove or the like on the polarized bulk piezoelectric material with use of a dicing blade. A pair of electrodes is formed on both the side faces of the partition to drive the piezoelectric material, and the liquid discharge head is finally constituted by forming a nozzle plate having nozzles thereon and an ink supply system (Japanese Patent Publication No. H06-006375).
The liquid discharge head which adopts the shear mode method can be manufactured with comparative ease. However, to obtain desired discharge speed, it is necessary to control the pressure to be applied to the liquid in the individual liquid chamber by shear-deforming the piezoelectric material with voltage (a potential difference) to be applied to both the sides of the partition constituted by the piezoelectric material.
In general, discharge performance of the piezoelectrically-actuated liquid discharge head is indicated by a relation between the voltage and the discharge speed, and it has been known that the discharge speed is proportionate to the voltage. To obtain the liquid discharge head which can achieve low power consumption and superior controllability for discharge speed, it is necessary to enable to discharge a droplet with low voltage and reduce a percentage of a change of the discharge speed to the voltage (hereinafter, called a voltage sensitivity).
Since the discharge speed is proportionate to the pressure to be applied to the liquid in the individual liquid chamber, it is possible to control the discharge speed by adjusting the pressure to be applied to the liquid based on kinds of piezoelectric material, and widths and heights of the partition and the individual liquid chamber. For example, to increase the pressure to be applied to the liquid, it is effective to enlarge a displacement volume of the individual liquid chamber by narrowing the width of the individual liquid chamber and/or heightening the height of the individual liquid chamber.
Incidentally, a relation between the displacement volume and the constitutions of the partition and the individual liquid chamber is expressed as follows. That is, if it is assumed that the displacement volume is ΔVol, a piezoelectric constant is d15, the height of the individual liquid chamber is H, the width of the partition is T, the voltage is V, and the length of the individual liquid chamber is z, then a relational expression ΔVol=(d15×H×z×V)÷(4×T) is given.
However, if it intends to enlarge the displacement volume over the entire longitudinal direction by changing the width of the partition and the height of the individual liquid chamber, a percentage of a change of the displacement volume to the voltage becomes large according to the above relational expression. Since the displacement volume and the pressure to be applied to the liquid are in a proportional relation, a percentage of a change of the voltage to the pressure to be applied to the liquid becomes large resultingly. That is, if it intends to increase the pressure to be applied to the liquid in the individual liquid chamber by simply adjusting the width and the height of the individual liquid chamber in order to discharge the droplet with low voltage, the voltage sensitivity of the discharge speed increases, and controllability of the discharge speed of the droplet deteriorates.
In particular, if the diameter of the nozzle is made small up to, e.g., 5 μm to 15 μm to discharge minute droplets, since the distance between the wall face of the nozzle and the center of the nozzle becomes close to each other, influences of viscosity resistance and surface tension become large, and flow speed of the liquid tends to concentrate on the center of the nozzle. Thus, it becomes difficult to cut off a liquid column formed from the nozzle to the discharge direction. Therefore, when the liquid column is cut off and thus the droplet is formed, since motion energy stored at the central portion of the nozzle is large, the discharge speed of the droplet is high. That is, by making the diameter of the nozzle small, the pressure to be applied to the liquid in the individual liquid chamber, i.e., the percentage of the change of the discharge speed of the droplet to the voltage to be applied to the pair of electrodes (the voltage sensitivity), becomes steep much more, and thus the controllability of the discharge speed of the droplets further deteriorates.
In line with this, the present invention aims to provide a liquid discharge apparatus which has improved controllability of the liquid discharge speed of the droplets.
The present invention is characterized by a liquid discharge apparatus comprising: a first substrate and a second substrate; a plurality of partitions, constituted by a piezoelectric material, which form a plurality of individual liquid chambers extending in a longitudinal direction; a nozzle member which is arranged on a side of a first end of the each individual liquid chamber, and on which a nozzle connected to the each individual liquid chamber is formed; a common liquid chamber forming member which is arranged on a side of a second end opposite to the first end of the each individual liquid chamber, and forms a common liquid chamber connected to the plurality of individual liquid chambers; and a plurality of pairs of electrodes each of which is arranged on both side faces of the each partition, such that the each partition is divided into a movable region to which an electric field for shear-deforming the each partition at a portion on the side of the nozzle is applied and an immovable region to which the electric field is not applied at a portion on the side of the common liquid chamber, wherein the each individual liquid chamber is formed such that a cross-section area of a cross section along a face perpendicular to the longitudinal direction at the second end is wider than a cross-section area of a cross section along the face perpendicular to the longitudinal direction at a first boundary point closest to the first end on a boundary between the movable region and the immovable region.
Moreover, the present invention is characterized by a liquid discharge apparatus comprising: a first substrate and a second substrate; a plurality of partitions, constituted by a piezoelectric material, which form a plurality of individual liquid chambers extending in a longitudinal direction; a plurality of pairs of electrodes each of which is arranged on both side faces of the each partition so as to shear-deform the each partition; a nozzle member which is arranged on a side of a first end of the each individual liquid chamber, and on which a nozzle connected to the each individual liquid chamber is formed; and a common liquid chamber forming member which is arranged on a side of a second end opposite to the first end of the each individual liquid chamber, and forms a common liquid chamber by surrounding together with the first substrate and the second substrate, wherein the each individual liquid chamber is connected to the common liquid chamber through a first opening opened to the longitudinal direction at the second end and a second opening opened to a height direction.
Moreover, the present invention is characterized by a manufacturing method of a liquid discharge apparatus in which a plurality of individual liquid chambers are formed by bonding a piezoelectric substrate on which partition grooves and front grooves have been processed and a second substrate to each other, and the plurality of individual liquid chambers are communicated with a common liquid chamber for supplying ink, the method comprising: forming the partition groove by forming a flat portion and a curved face portion deeper than the flat portion on the piezoelectric substrate, wherein the curved face portion is communicated with the common liquid chamber.
Moreover, the present invention is characterized by a manufacturing method of a liquid discharge apparatus in which a plurality of individual liquid chambers are formed by bonding a piezoelectric substrate on which partition grooves and front grooves have been processed and a second substrate to each other, and the plurality of individual liquid chambers are communicated with a common liquid chamber for supplying ink, the method comprising: preparing the second substrate in which a counterbore portion has been formed, wherein the counterbore portion is arranged such that the counterbore portion constitutes a part of the common liquid chamber and the counterbore portion and the plurality of individual liquid chambers are communicated.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Preferred embodiments of the present invention will now be described in detail in accordance with the accompanying drawings.
A manifold 40 which serves as a common liquid chamber forming member, and on which an ink supply port 41 and an ink recovery port 42 both communicated with an ink tank (not illustrated) are provided is connected to the back face side of the discharge unit 10. Moreover, a plurality of front face grooves 7 each of which is communicated with each dummy chamber 2 are formed on the front face side of the discharge unit 10. A flexible substrate 50 is bonded to the upper face of the discharge unit 10.
As illustrated in
Each partition 3 is formed longwise, and the plurality of individual liquid chambers 1 and the plurality of dummy chambers 2 extending in the longitudinal direction A2 are formed by the plurality of partitions 3. Each partition 3 is constituted by a piezoelectric material which is polarized in the height direction C.
Moreover, as illustrated in
A bottom face electrode 17 which is continuously connected to the signal electrode 14 and thus electrically conducted to the signal electrode 14 and a bottom face electrode 18 which is continuously connected to the signal electrode 15 and thus electrically conducted to the signal electrode 15 are formed on one face 12a of the second substrate 12. The bottom face electrodes 17 and 17 which are formed respectively on the facing sides in the dummy chamber 2 are separated from each other by a groove 19 and thus electrically insulated.
The signal electrode 14 is electrically connected to an extraction electrode 4 through the front face electrode formed in the front face groove 7 illustrated in
As illustrated in
In the present embodiment, as illustrated in
If it is assumed that the individual liquid chamber 1 has a height H and the individual liquid chamber 1 has a width W, as illustrated in
As illustrated in
As indicated by the arrows illustrated in
Subsequently, a method of applying the voltage to each of the electrodes 14 and 15 will be described.
As illustrated in
As illustrated in
In the above electrode constitution, when a voltage VA is applied from the flexible substrate 50 (
Subsequently, an operation of the inkjet head 100 according to the present embodiment will be described.
Further,
Furthermore,
On each partition 3, each electrode pair 13 is arranged on both the side faces of each partition 3 so as to divide the partition into a movable region R1 which corresponds to the portion on the side of the nozzle and to which the electric field for shear-deforming the partition is applied and an immovable region R2 which corresponds to the portion on the side of the common liquid chamber and to which the electric field is not applied. Here, the electrodes constituting each electrode pair faces each other with the movable region R1 therebetween.
Incidentally, in the present embodiment, on both the side faces of the partition 3, a conductor is formed on the overall side face on the side of the individual liquid chamber 1 and the overall side face on the side of the dummy chamber 2. However, only the portions mutually overlapping each other in the width direction B constitute the electrodes 14 and 15.
Here, it is assumed that, when viewed from the width direction B, the individual liquid chamber has a first boundary point P1 closest to the first end 1a on a boundary X between the movable region R1 and the immovable region R2, and a second boundary point P2 closest to the second end 1b on the boundary X. Moreover, it is assumed that the individual liquid chamber 1 has a cross-section area S1 along the face perpendicular to the longitudinal direction A2 on the first boundary point P1 and a cross-section area S2 along the face perpendicular to the longitudinal direction A2 on the second end 1b.
Each individual liquid chamber 1 is formed such that the cross-section area S2 is wider than the cross-section area S1. In the present embodiment, the width of the individual liquid chamber 1 is formed to have a certain length from the first end 1a to the second end 1b. Therefore, in the present embodiment, a height H2 of each individual liquid chamber 1 at the second end 1b is higher than a height H1 of each individual liquid chamber 1 at the first end 1a.
More specifically, as illustrated in
At this time, if it is assumed that, in the individual liquid chamber 1, the cross section has a cross-section area S along the face perpendicular to the longitudinal direction A2, the cross-section area S becomes large from the first boundary point P1 to the common liquid chamber 43 in the longitudinal direction A2, and the cross-section area S2 of the face being in contact with the common liquid chamber 43 is the maximum area as the cross-section area S.
In the present embodiment, each individual liquid chamber 1 is formed such that the cross-section area S of the cross section along the face perpendicular to the longitudinal direction A2 of each individual liquid chamber 1 becomes continuously wide as the relevant cross section approaches the second end 1b from the first boundary point P1. Incidentally, although the cross-section area S continuously changes in the present embodiment, it is possible to form the individual liquid chamber such that the cross-section area S becomes wide gradually.
In the present embodiment, a total length L of the individual liquid chamber 1 in the longitudinal direction A2 is the sum of a length L1 from the first end 1a to the second boundary point P2 and a length L2 from the second boundary point P2 to the second end 1b, and is within a range of 6 mm to 14 mm.
Besides, the width T of the partition 3 (
Further, the height H1 of the individual liquid chamber 1 at the first boundary point P1 is within a range of 100 μm to 400 μm, and the height H2 of the individual liquid chamber 1 at the face being in contact with the common liquid chamber 43 is within a range of 400 μm to 1500 μm.
The operation of the inkjet head 100 according to the present embodiment will be described hereinafter.
At this time, since the cross-section area S in the individual liquid chamber 1 becomes large from the boundary point P1 (
Moreover, since the cross-section area S becomes continuously (or gradually) wide as it approaches the second end 1b from the first boundary point P1, the ink easily flows more effectively. Therefore, the controllability of the discharge speed of the droplet discharged from the nozzle 30a is further improved.
As just described, in order to reduce the voltage sensitivity, it is effective to control the flow of the ink toward the common liquid chamber 43 by reducing a percentage of the portion corresponding to the immovable region R2 to the portion corresponding to the movable region R1 in the individual liquid chamber 1.
On the other hand, in order to discharge the droplet from the nozzle 30a by lowering the voltage to be applied to the electrode pair 13, it is effective to increase the pressure applied to the ink by enlarging a displacement volume per unit voltage in the movable region R1.
In consideration of the above, it is suitable in the individual liquid chamber 1 to adjust a cross-section area ratio between the cross-section area of the portion corresponding to the movable region R1 and the cross-section area of the portion corresponding to the immovable region R2 and a ratio between the length of the portion corresponding to the movable region R1 and the length of the portion corresponding to the immovable region R2. Namely, it is possible, by adjusting these ratios, to discharge the droplet from the nozzle 30a with a desirable voltage sensitivity.
Next, a manufacturing method of the inkjet head 100 according to the present embodiment will be described. Initially, as illustrated in
Subsequently, as illustrated in
An example that the partition groove 25 are formed using the dicing blade will be described with reference to
Subsequently, the process of the front face groove 7 will be described with reference to
The front face groove 7 is processed at the center between the two individual liquid chambers 1 as illustrated in
Next, as illustrated in
Subsequently, as illustrated in
Next, as illustrated in
As the method of applying the adhesive 16, it is possible to directly apply the adhesive to the tips 3a of the partitions 3 using a method such as a screen printing method or a bar coater method capable of adjusting the thickness of the adhesive. Alternately, it is possible to once apply the adhesive to a film or a glass substrate and then transfer the applied adhesive to the tips. Incidentally, for example, an epoxy adhesive, a phenolic adhesive or a polyimide adhesive can be used as the adhesive 16.
After then, the front face of the discharge unit 10 is grinded and polished to eliminate the conductive layer 26 and have desired dimensions and shapes. Further, an extraction electrode dividing groove 27 is formed on the upper face of the discharge unit 10, thereby obtaining the individual electrodes 4 respectively divided electrically.
By a series of the above processes, the discharge unit 10 is formed, and then the nozzle plate 30, the manifold 40, the flexible substrate 50 and the like are attached as illustrated in
Subsequently, a liquid discharge apparatus according to the second embodiment will be described. Also, in the present embodiment, the liquid discharge apparatus corresponds to an inkjet head.
As well as the first embodiment, in the partition 3 which constitutes an individual liquid chamber 1, since the portion sandwiched by an electrode pair 13 is shear-deformed, this portion is a movable region R1 and the portion other than the movable region R1 is an immovable region R2, as illustrated in
As illustrated in
Moreover, in the individual liquid chamber 1, the cross-section area S corresponds to a certain flat portion from a first end 1a on the side of the nozzle to the midway toward the second end 1b on the side of the common liquid chamber in the longitudinal direction A2, the portion sandwiched by the movable regions R1 is a movable region flat portion 206, and the entire flat portion is an individual liquid chamber flat portion 207. In the longitudinal direction A2, the length of the individual liquid chamber flat portion 207 is longer than the length of the movable region flat portion 206.
In the individual liquid chamber 1, when a cross-section area S1 and the cross-section area S2 are compared with each other, the cross-section area S2 is wider than the cross-section area S1. More specifically, a width W of the individual liquid chamber 1 is constant, and a height H2 of the individual liquid chamber 1 is higher than a height H1.
Further, the cross-section area S of the individual liquid chamber 1 is constant from the first boundary point P1 to the midway toward the second end 1b, and then becomes continuously wide as it approaches the second end 1b from the midway.
As well as the first embodiment, also by the above constitution, since the cross-section area S in the individual liquid chamber 1 becomes large from the boundary point P1 to a common liquid chamber 43 in the longitudinal direction A2, it is possible to enlarge the flow of the ink toward the common liquid chamber 43. That is, since the resistance in the ink flow path at the portion corresponding to the immovable region R2 in the individual liquid chamber 1 is smaller than the resistance in the ink flow path at the portion corresponding to the movable region R1 in the individual liquid chamber 1, the ink easily flows to the side of the second end 1b at the time of compression of the individual liquid chamber 1. As a result, the flow of the ink toward the side of the nozzle 30a is reduced at the time of the discharge of a droplet, and it is thus possible to reduce a percentage of a change of the discharge speed to the pressure applied to the ink in the individual liquid chamber 1, that is, it is possible to reduce a voltage sensitivity. Thus, controllability of the discharge speed of the droplet discharged from the nozzle 30a is improved.
Subsequently, a liquid discharge apparatus according to the third embodiment will be described. Also, in the present embodiment, the liquid discharge apparatus corresponds to an inkjet head.
In the third embodiment, a movable region R1 of the partition 3 stretches up to the portion corresponding to the region in which the height of an individual liquid chamber 1 is heightened toward the common liquid chamber in a longitudinal direction A2. More specifically, as illustrated in
At this time, a cross-section area S of the individual liquid chamber 1 becomes large from a first boundary point P1 toward the common liquid chamber in the longitudinal direction A2, and a cross-section area S2 of the individual liquid chamber 1 at the face being in contact with the common liquid chamber is the maximum area as the cross-section area S.
As well as the first embodiment, also by the above constitution, since the cross-section area S in the individual liquid chamber 1 becomes large from the boundary point P1 to a common liquid chamber 43 in the longitudinal direction A2, it is possible to enlarge the flow of the ink toward the common liquid chamber 43. That is, since the resistance in the ink flow path at the portion corresponding to an immovable region R2 in the individual liquid chamber 1 is smaller than the resistance in the ink flow path at the portion corresponding to the movable region R1 in the individual liquid chamber 1, the ink easily flows to the side of a second end 1b at the time of compression of the individual liquid chamber 1. As a result, the flow of the ink toward the side of the nozzle 30a is reduced at the time of the discharge of a droplet, and it is thus possible to reduce a percentage of a change of the discharge speed to the pressure applied to the ink in the individual liquid chamber 1, that is, it is possible to reduce a voltage sensitivity. Thus, controllability of the discharge speed of the droplet discharged from the nozzle 30a is improved.
Subsequently, a liquid discharge apparatus according to the fourth embodiment will be described. Also, in the present embodiment, the liquid discharge apparatus corresponds to an inkjet head.
In the fourth embodiment, the height of an individual liquid chamber 1 is heightened gradually from a first end 1a on the side of the nozzle toward a first boundary point P1 in a longitudinal direction A2. Moreover, as illustrated in
As well as the first embodiment, also by the above constitution, since the cross-section area S in the individual liquid chamber 1 becomes large from the boundary point P1 to a common liquid chamber 43 in the longitudinal direction A2, it is possible to enlarge the flow of the ink toward the common liquid chamber 43. That is, since the resistance in the ink flow path at the portion corresponding to an immovable region R2 in the individual liquid chamber 1 is smaller than the resistance in the ink flow path at the portion corresponding to the movable region R1 in the individual liquid chamber 1, the ink easily flows to the side of a second end 1b at the time of compression of the individual liquid chamber 1. As a result, the flow of the ink toward the side of the nozzle 30a is reduced at the time of the discharge of a droplet, and it is thus possible to reduce a percentage of a change of the discharge speed to the pressure applied to the ink in the individual liquid chamber 1, that is, it is possible to reduce a voltage sensitivity. Thus, controllability of the discharge speed of the droplet discharged from the nozzle 30a is improved.
In a liquid discharge head to be used for industrial purposes, as well as stable liquid discharge, high-definition liquid discharge is needed. Particularly, in the liquid discharge head of the shear mode method, in a case where the nozzle diameter is set to, e.g., φ15 μm or less, minute droplets are separated at high speed before main droplets are discharged if the droplet speed is set to a certain speed or more. In the case where the minute droplet is formed before the main droplet and the droplet speed is high, since the minute droplet reaches a target substrate before the main droplet reaches the target substrate, there is a problem that drawn dots are distorted. In addition, since the droplet separated before the main droplet is extremely minute in size, an influence of deceleration by air resistance is high for the separated minute droplet. Thus, there is a high possibility that the minute droplet is floated due to disturbance before it reaches the target substrate, and thus the minute droplet reaches an unintended location. According to the present embodiment, it is possible to solve such a further problem that high-definition drawing cannot be performed if the minute droplets are formed before the main droplets.
In the present embodiment, the constitutions same as those described in the first embodiment are added with the same corresponding numerals and symbols respectively and descriptions of these constitutions will be omitted.
As illustrated in
The common liquid chamber 43 is connected to each individual liquid chamber 1. An ink is supplied from a not-illustrated ink tank to the common liquid chamber 43 through an ink supply port 41. The ink supplied to the common liquid chamber 43 is filled in each individual liquid chamber 1. Then, when an electric field is applied by an electrode pair 13 in the direction orthogonal to a polarization direction, a partition 3 is shear-deformed, and thus the volume of the individual liquid chamber 1 is changed. Thus, the ink (i.e., an ink droplet) which is the liquid (a liquid droplet) is discharged from a nozzle 30a.
In the present embodiment, as illustrated in
As indicated by the arrows illustrated in FIG. 14B, the partition 3, which protrudes from the one face 11a of the first substrate 11, has a chevron structure in which a base-side piezoelectric material 3A polarized in parallel with a height direction C and a tip-side piezoelectric material 3B polarized in the opposite direction are boned to each other by an adhesive 3C.
In the present embodiment, the diameter of the nozzle 30a is within a range of 5 μm to 15 μm. That is, the diameter of the nozzle 30a is made small to have a minute amount (e.g., 1 pl to 3 pl) of the droplet to be discharged from the nozzle 30a.
Each individual liquid chamber 1 is connected to the common liquid chamber 43 through a first opening 1c opening at the second end 1b toward the longitudinal direction A2 and a second opening 1d opening toward the height direction C. That is, the first opening 1c faces the face perpendicular to the longitudinal direction A2, and the second opening 1d faces the face perpendicular to the height direction C.
As just described, the individual liquid chamber 1 is in contact with the common liquid chamber 43 with the two faces. The second opening 1d is arranged on the side of the second end 1b, and extends from the second end 1b to the first end 1a on the side of the nozzle along the longitudinal direction A2. The opening directions of the first opening 1c and the second opening 1d are orthogonal to each other.
A counterbore portion (or a concave portion) 12c is formed in the second substrate 12. The common liquid chamber 43 is constituted by a liquid chamber portion 43A which is the space formed by the manifold 40, and a liquid chamber portion 43B which is communicated with the liquid chamber portion 43A and is the space formed by the counterbore portion (or the concave portion) 12c in the second substrate 12. As illustrated in
The counterbore portion 12c is formed by drilling so as to have the depth of 0.2 mm to 1 mm. Further, a length L1 of the counterbore portion 12c in the longitudinal direction A2 is 0.2 to 0.7 times of a total length L2 of the individual liquid chamber 1 in the longitudinal direction A2.
Moreover, the dummy chamber 2 is formed so as not to overlap the second opening 1d in the width direction B. That is, the length of the dummy chamber 2 in the longitudinal direction A2 is set such that the dummy chamber 2 and the second opening 1d do not overlap in the width direction B. In other words, the dummy chamber 2 is formed to be shorter than the individual liquid chamber 1 in the longitudinal direction A2 such that the dummy chamber 2 and the liquid chamber portion 43B of the common liquid chamber 43 are not in contact with each other. Thus, the dummy chamber 2 and the common liquid chamber 43 are not communicated with each other.
In the present embodiment, since the ink is introduced from the two directions in the individual liquid chamber 1, the flow of the ink is disturbed in the individual liquid chamber 1. Thus, in addition to the flow of the ink to the nozzle 30a in a liquid discharge direction A1, a flow is locally generated in the direction orthogonal to the liquid discharge direction A1. By such an action, the flow speed for concentrating the flow near the liquid inlet of the nozzle 30a on the central portion of the nozzle 30a is relieved. As a result, since the phenomenon that the minute droplets are separated from the main droplets can be restrained, it is possible to stably discharge the droplets.
Incidentally, since the first opening 1c and the second opening 1d are formed to be in contact with each other, the one large opening in which the first opening 1c and the second opening 1d are communicated with each other is formed. Consequently, since the resistance in the ink flow path in the individual liquid chamber 1 is reduced, the ink easily flows from each of the openings 1c and 1d into the individual liquid chamber 1. Thus, it is possible to more effectively relieve that the flow speed of the ink is concentrated on the central portion of the nozzle 30a. Therefore, it is possible to more effectively restrain the phenomenon that the minute droplets are separated from the main droplets.
Moreover, the first opening 1c coincides with the cross section along the face perpendicular to the longitudinal direction A2 at the second end 1b of the individual liquid chamber 1, that is, the end face at the second end 1b of the individual liquid chamber 1. That is, since the opening area on the rear side of the individual liquid chamber 1 is maximum, any choked portion is not formed. For this reason, since the threshold of the main droplet speed at which the minute droplet is generated further increases, it is possible to more effectively restrain the phenomenon that the minute droplets are separated from the main droplets.
Subsequently, a manufacturing method of the inkjet head 100 will be described. Initially, a manufacturing method of the piezoelectric substrate 24 will be described with reference to
To form the piezoelectric plate 23A, the piezoelectric material is first processed into a desired shape. Then, an HIP (Hot Isostatic Pressing) process is performed. More specifically, a ceramic material once sintered is further baked and hardened in gas pressure of 1000° C. or more and 1000 atmospheric pressures or more. It is possible by this process to reduce voids (bubbles) in the sintered body, and this process is used mainly for microfabrication. Then, Ag paste of about several micrometers (μm) is formed as the electrodes for polarization on the upper and lower faces of the HIP-processed substrate. Next, an electric field of 2 kV/mm to 5 kV/mm is applied to the electrodes for polarization. Finally, the used electrodes for the polarization are ground away, thereby forming the piezoelectric plate 23A. Here, the polarization direction is indicated by an arrow P1 illustrated in
Likewise, a polarized piezoelectric plate 23B illustrated in
Subsequently, as illustrated in
Next, the processing of the individual liquid chamber 1 will be described with reference to
Next, the processing of the dummy chamber 2 will be described with reference to
It should be noted that the constitution having the dummy chamber 2 has an advantage that the individual liquid chamber 1 can be solely controlled. The thickness of the dicing blade is 60 μm to 150 μm, and the diameter of the dicing blade is about φ51 mm to φ102 mm in general. To process the piezoelectric material, the diamond abrasive grains of about #1000 to #1600 are used. The resin bond is preferably used as the abrasive grain bond. Further, any problem does not occur if at least the device capable of using the two-axis control is used as the dicing device. Furthermore, the rotation speed of the dicing blade is about 2000 rpm to 30000 rpm. To reduce the stress to the process member at the time when the processing is performed by the dicing blade, the stage transport speed is set to 0.1 mm/s to 0.5 mm/s.
The processing position of the dummy chamber 2 is the center between the two individual liquid chambers 1, as illustrated in
Next, the processing of extraction electrode grooves (i.e., front face grooves) 7 will be described with reference to
Subsequently, the processing of the electrode pairs 13 will be described with reference to
A conductor 26 serving as the electrode is formed on the surface of the piezoelectric substrate 24 having an electrical insulation property by an electroless plating process. Here, the electroless plating process is the process for forming an Ni plating or the like. In the electroless plating procedure, a minute recess is first formed on the surface of the piezoelectric substrate 24 by an appropriate etching agent. Next, a deleading process for eliminating Pb widely used as a piezoelectric material is performed. Further, a process of adsorbing Sn and Pd on the outermost surface as plating catalyst is performed. First, the substrate is immersed in a stannous chloride solution of 0.1% concentration so that stannous chloride is adsorbed. Subsequently, metallic palladium is adsorbed on the surface by an oxidation-reduction reaction of adsorbed stannous chloride and palladium chloride. In this state, the substrate is immersed in the Ni plating solution, so that the conductor 26 composed of an electroless plating film of Ni is grown. It is possible as a Ni plating layer to use either a Ni—P layer or a Ni—B layer. Here, the film thickness is determined in consideration of surface covering and a resistance value, and thus set to about 0.5 μm to 2.0 μm.
Subsequently, elimination of an unnecessary portion will be described. Here, as the portions to be eliminated, the upper-side portion of the partition 3 and the nozzle plate bonding face are eliminated by grinding. As the elimination amount, the portion corresponding to about 3 to 10 times the thickness of the conductor 26 being the plating film may be eliminated.
Subsequently, the divided signal electrodes 14 and 14 are provided by a dividing groove 19 at the bottom of the dummy chamber 2, so as to individually drive the partition 3 for each individual liquid chamber 1. The dividing groove 19 is processed by the dicing blade in the same manner as that for the above groove processing. Here, it is preferable to set the width of the dividing groove 19 to about ½ to ⅓ of the dummy chamber 2, and to set the depth thereof to about 10 μm to 50 μm. The dividing position is equivalent to the entire of the bottom portion of the dummy chamber 2 in the longitudinal direction and the front face in the extraction electrode groove 7. As just descried, since the electrode is divided into the signal electrodes 14 and 14 by the dividing groove 19 in the dummy chamber 2, it is possible to electrically insulating the mutual signal electrodes 14 corresponding to the respective individual liquid chambers 1.
Subsequently, the processing of a clearance groove 6 will be described with reference to
Next, the plurality of nozzles 30a for discharging the ink are formed on the nozzle plate 30 (
Then, the nozzle plate 30, the manifold 40, the second substrate 12 and the flexible substrate 50 are aligned and bonded to the first substrate 11 (i.e., the processed piezoelectric substrate 24) on which the partitions 3 have been provided, thereby completing the inkjet head 100. More specifically, the second substrate 12 on which the counterbore portion (the concave portion) 12c (
Subsequently, a liquid discharge apparatus according to the sixth embodiment of the present invention will be described. Also, in the present embodiment, the liquid discharge apparatus corresponds to an inkjet head.
As well as the first embodiment, an inkjet head 100A comprises substrates 11 and 12, a nozzle plate 30 and a manifold 40. Moreover, as well as the first embodiment, the inkjet head 100A comprises a plurality of partitions, a plurality of individual liquid chambers 1 and a plurality of dummy chambers 2.
On each partition 3, each electrode pair 13 is arranged on both the side faces of each partition 3 so as to divide the partition into a movable region R1 which corresponds to the portion on the side of the nozzle and to which an electric field for shear-deforming the partition is applied and an immovable region R2 which corresponds to the portion on the side of the common liquid chamber and to which the electric field is not applied. Here, the electrodes constituting each electrode pair faces each other with the movable region R1 therebetween.
Incidentally, in the sixth embodiment, on both the side faces of the partition 3, a conductor is formed on the overall side face on the side of the individual liquid chamber 1 and the overall side face on the side of the dummy chamber 2. However, only the portions (the slant portion in
Here, it is assumed that, when viewed from the width direction, the individual liquid chamber has a boundary point P closest to a first end 1a on a boundary X between the movable region R1 and the immovable region R2. Moreover, it is assumed that the individual liquid chamber 1 has a cross-section area S1 along the face perpendicular to a longitudinal direction A2 on the boundary point P and a cross-section area S2 along the face perpendicular to the longitudinal direction A2 on a second end 1b.
Each individual liquid chamber 1 is formed such that the cross-section area S2 is wider than the cross-section area S1. In the sixth embodiment, the width of the individual liquid chamber 1 is formed to have a certain length from the first end 1a to the second end 1b. Therefore, in the sixth embodiment, a height H2 of each individual liquid chamber 1 at the second end 1b is higher than a height H1 of each individual liquid chamber 1 at the boundary point P.
At this time, in the individual liquid chamber 1, the cross-section area along the face perpendicular to the longitudinal direction A2 becomes large from the boundary point P to a common liquid chamber 43 in the longitudinal direction A2, and the cross-section area S2 of the face being in contact with the common liquid chamber 43 is the maximum area as the cross-section area of the individual liquid chamber 1.
In the sixth embodiment, each individual liquid chamber 1 is formed such that the cross-section area of the cross section along the face perpendicular to the longitudinal direction A2 of each individual liquid chamber 1 becomes continuously wide as the relevant cross section approaches the second end 1b from the boundary point P. Incidentally, although the cross-section area S continuously changes in the present embodiment, it is possible to form the individual liquid chamber such that the cross-section area S becomes wide gradually. Therefore, in the individual liquid chamber 1, since the center of pressure is deviated from the central portion to the side of the nozzle in the longitudinal direction A2, it is possible to effectively apply the pressure to the ink which is the liquid in the nozzle.
Moreover, since each individual liquid chamber 1 is formed such that the height at the first end 1a is lower than the height at the boundary point P closest to the first end 1a on the boundary between the movable region R1 and the immovable region R2. Therefore, it is possible to effectively apply the pressure to the ink being the liquid in the vicinity of the nozzle.
In the sixth embodiment, as well as the fifth embodiment, even if the amount of the droplets to be discharged is made small by reducing the diameter of each nozzle, the minute droplets are not separated and generated before the main droplets. Therefore, it is possible to stably discharge the droplets.
Subsequently, a liquid discharge apparatus according to the seventh embodiment will be described. Also, in the present embodiment, the liquid discharge apparatus corresponds to an inkjet head.
As well as the first embodiment, an inkjet head 100B comprises substrates 11 and 12, a nozzle plate 30 and a manifold 40. Moreover, as well as the first embodiment, the inkjet head 100B comprises a plurality of partitions, a plurality of individual liquid chambers 1 and a plurality of dummy chambers 2.
In the above fifth embodiment, the counterbore portion 12c is formed in the second substrate 12, and the liquid chamber portion 43B of the common liquid chamber 43 to be connected to the individual liquid chamber 1 through the second opening 1d is formed. However, the present invention is not limited to this constitution. Namely, the counterbore portion may be formed at least one of the first and second substrates. More specifically, as illustrated in
Incidentally, the present invention is not limited to the above embodiments, that is, various modifications can be achieved by a person skilled in this field of art within the technical concept of the present invention.
In the above embodiments, the inkjet head to be used in a printer or the like has been described as the liquid discharge head. However, the present invention is not limited to this. For example, a head for discharging, as a liquid, a liquid containing metal fine particles to be used when forming metal wirings may be used as the liquid discharge head. Moreover, a head for discharging resist ink to be used for resist patterning may be used.
Besides, in the above embodiments, the case where the partition is the piezoelectric material constituted by bonding the base-side piezoelectric material polarized in the height direction and the tip-side piezoelectric material polarized in the direction opposite to that of the base-side piezoelectric material has been described. However, the partition may be constituted by a piezoelectric material polarized in one direction, i.e., the height direction.
The length L of the individual liquid chamber 1 in the longitudinal direction A2 is 12 mm, and the cross-section area S of the individual liquid chamber 1 becomes large from the first boundary point P1 to the common liquid chamber 43 in the longitudinal direction A2. The cross-section area S2 of the individual liquid chamber 1 being in contact with the common liquid chamber 43 is larger than the cross-section area S1 of the individual liquid chamber 1 at the first boundary point P1, and the cross-section area S2 is the maximum cross-section area in the individual liquid chamber 1. More specifically, the height H1 of the individual liquid chamber 1 at the first boundary point P1 is 240 μm, the height H2 of the individual liquid chamber 1 at the face being in contact with the common liquid chamber 43 is 650 μm, and the width W (
Moreover, the length L1 between the first end 1a (the nozzle 30a) and the second boundary point P2 in the longitudinal direction A2 is 7.3 mm, and the length L2 between the second boundary point P2 and the second end 1b (the common liquid chamber 43) in the longitudinal direction A2 is 4.7 mm.
The cross-section area S is expressed by the product of the height H of the individual liquid chamber 1 and the width W of the individual liquid chamber 1. If the ratio between the cross-section area S1 and the cross-section area S2 is R11 (=S1/S2), the ratio R11 of these cross-section areas in the individual liquid chamber 1 is 2.7. Moreover, if the ratio between the length L1 and the length L2 is R12 (=L2/L1), the ratio R12 of these lengths is 0.64.
More specifically, the length L of the individual liquid chamber is 12 mm as well as the example, the length L1 is 11 mm, the length L2 is 1 mm, and the width W of the individual liquid chamber is 60 μm.
Moreover, the height H1 of the individual liquid chamber at the first boundary point P1 is 240 μm, and also the height H2 of the individual liquid chamber at the face being in contact with the common liquid chamber is 240 μm. The ratio R11 of the cross-section areas S1 and S2 is 1.0, and the ratio R12 of the lengths L1 and L2 is 0.09.
Moreover, the length L1 is 7.3 mm as well as the example, the length L2 is 0.7 mm, the ratio R11 of the cross-section areas S1 and S2 is 1.0, and the ratio R12 of the lengths L1 and L2 is 0.09.
Besides, in the example 1 (
In the comparative example 1, the voltage sensitivity is high, i.e., 2.0 m/s/V. On the other hand, the voltage sensitivity in the comparative example 2 in which the total length L of the individual liquid chamber is shorter than that in the comparative example 1 is 1.4 m/s/V, and thus the voltage sensitivity can be reduced in comparison with the comparative example 1. However, the voltage threshold for discharging the droplet in the comparative example 2 is higher than that in the comparative example 1. Besides, in the example 1, it is possible to reduce the voltage sensitivity to the value lower than those in the comparative examples 1 and 2 without increasing the voltage threshold for discharging the droplet in comparison with the comparative example 1.
It can be understood from the graph that the voltage sensitivity becomes larger as the nozzle diameter is made smaller. Namely, to obtain the desirable voltage sensitivity of 0.5 m/s/V to 1.0 m/s/V, it can be understood that at least 30 μm is necessary as the nozzle diameter in the comparative example 1, and at least 20 μm is necessary as the nozzle diameter in the comparative example 2. On the other hand, in the example 1, it is possible to obtain the effective result when the nozzle diameter is within the range of 5 μm to 15 μm.
In addition, the length L of the individual liquid chamber 1 is 12 mm, the length L1 from the nozzle 30a to the second boundary point P2 in the longitudinal direction A2 is 7.3 mm, and the length L2 from the second boundary point P2 to the common liquid chamber 43 is 4.7 mm. The height H1 of the individual liquid chamber 1 is 240 μm, the width W of the individual liquid chamber 1 is 60 μm, and the width T of the partition is 70 μm.
It can be understood that, to obtain the desirable voltage sensitivity of 0.5 m/s/V to 1.0 m/s/V, it is preferable to set the cross-section area ratio R11 of the individual liquid chamber 1 within the range of 1.8 to 3.5.
It is understood from
If the partition 3 forming the individual liquid chamber 1 is entirely set as the movable region, the voltage sensitivity is excessively lowered. However, it is possible to obtain the appropriate value as the voltage sensitivity by dividing the partition 3 into the movable region to which the electric field for shear-deforming the partition at the portion on the side of the nozzle is applied and the immovable region to which the electric field is not applied at the portion on the side of the common liquid chamber. Moreover, it is possible to obtain the desirable voltage sensitivity by setting the ratio R12 within the range of 0.6 to 1.7.
Subsequently, the inkjet head according to the example 3 will be described. More specifically, the PZT (lead zirconate titanate: PbTiZrO3) was used as the material of the piezoelectric plates 23A and 23B illustrated in
Next, the piezoelectric plate 23A and the piezoelectric plate 23B were bonded to each other by the epoxy adhesive as the adhesive 3C. At this time, the two-liquid mixing and thermosetting adhesive (2022 (base compound), 2131D (hardener)) manufactured by ThreeBond Co., Ltd. was used. The epoxy adhesive of 10 μm was applied to the upper face by the screen printing method such that the polarization direction of the piezoelectric substrate 23A faces downward. Then, the piezoelectric plate 23B was bonded to the face on which the adhesive 3C had been applied, such that the polarization direction faces upward. Then, the piezoelectric plates 23A and 23B were heated at 100° C., pressed to be bonded to each other, held for one hour, and hardened, so that the piezoelectric substrate 24 was formed.
As illustrated in
Next, as illustrated in
Next, as illustrated in
Next, as illustrated in
Next, the upper portion of the nozzle plate bonding face of the partition 3 were eliminated by 5 μm through the grinding. Then, the dividing groove 19 for dividing the signal electrode into the signal electrodes 14 and 14 at the bottom of the dummy chamber 2 was formed to individually drive the partition 3 for each individual liquid chamber 1. Here, the electrode was divided and processed by the dicing blade. The blade width was 40 μm, and the processing depth of the dividing groove 19 was 20 μm.
Moreover, as illustrated in
As illustrated in
The manifold 40 comprises the ink supply port 41 for supplying the ink to the individual liquid chambers 1. In the example 3, the ink output was provided at the position symmetrical with respect to the ink supply port 41 so as to circulate the ink.
The material of the second substrate 12 serving as the top panel was the PZT same as the material of the first substrate 11. The counterbore portion 12c was formed by the drilling in the second substrate 12. The depth thereof was 600 μm, the length of the second opening 1d of the individual liquid chamber 1 in the longitudinal direction A2 was 0.4 times of the total length of the individual liquid chamber 1 in the longitudinal direction A2.
The flexible substrate 50 comprises thereon the electrodes 51 for connecting the respective individual liquid chambers 1 to the ground and the electrodes 52 for individually applying electrical signals to the signal electrodes 14 provided on the dummy-chamber sides of the respective partitions 3. Moreover, on the face of the first substrate 11 opposite to the face on which the partitions 3 were provided, the plating was formed entirely at the same time when the electrodes were formed. Consequently, on the face of the first substrate 11 opposite to the face on which the partitions 3 were provided, the dividing groove for dividing the individual signal line corresponding to the signal electrode 14 on the side of the dummy chamber 2 was formed by using the excimer laser. Further, the dividing groove for electrically dividing the individual signal line from the GND electrode signal line of the individual liquid chamber 1 was formed by using the excimer later. The flexible substrate 50 and the first substrate 11 were aligned and bonded to each other by the thermal compression process, thereby electrically connecting these substrates to each other.
Finally, as illustrated in
As a comparative example 3, the inkjet head in which the material and external dimensions of the second substrate were respectively the same as those in the example 3 and which did not have the processed counterbore portion was formed.
In the example 3, the mixture composed of ethylene glycol 85% and water 15% was used as the ink for the inkjet head 100. The ink was introduced from the ink supply port 41 of the manifold 40 through the Tygon™ tube.
The rectangular pulses having the pulse width 8 μs were applied as the driving condition for discharging the droplets. The discharge frequency was 5000 Hz, and the microscope observation of the discharge state was performed. Then, the driving voltage was swept, and the flying state (the discharge state) of the droplet was evaluated.
An example of the evaluation is shown in
The discharge speed of the main droplet increases if the driving voltage is increased. If the driving voltage is further increased, the minute droplet tends to be separated and generated before the main droplet according to the nozzle diameter in the case where the discharge speed exceeds the certain speed. The maximum main droplet speeds at this time are shown by Table 2. In particular, as the industrial inkjet head, the speed of the main droplet of 5 m/s or more is necessary in consideration of impact accuracy.
In the example 3, it can be understood from Table 2 that, when the diameter of the nozzle 30a was φ5 μm or more, the normal discharge in which the minute droplet was not separated at the head could be achieved even if the discharge speed of the main droplet was 5 m/s or more (better). On the other hand, when the diameter of the nozzle 30a was φ4 μm or less, the stable discharge could not be achieved and thus the nozzle was in the no discharge state (no good). Further, when the diameter of the nozzle exceeded φ15 μm, the discharge speed of the main droplet could be 5 m/s or more even in the comparative example 3 (good).
That is, in the individual liquid chamber 1 having the shear-mode constitution, with respect to the diameters φ5 μm to φ15 μm of the nozzle 30a, the effect of the example 3 in which the two contact faces with the common liquid chamber 43 positioned on the rear side of the nozzle 30a were provided could be confirmed.
The flow of the ink was stable in regard to the nozzle on the ink supply face at only the rear portion in the comparative example 3. Therefore, any problem does not occur if the nozzle has the normal diameter. However, if it intends to reduce the droplet by reducing the nozzle diameter, the phenomenon that the flow speed of the ink in the individual liquid chamber abruptly increases at the central portion in the minute area of the nozzle occurs.
In the example 3, since the flow of the ink is introduced in the two directions from the rear side, the flow of the ink is disturbed. Thus, in addition to the flow toward the liquid discharge direction, the flow is locally generated toward the direction orthogonal to the liquid discharge direction. By the effect of this example, the flow speed distribution in which the flow near the liquid inlet of the nozzle 30a is concentrated on the central portion of the nozzle 30a is relieved. As a result, the phenomenon that the minute droplet is separated from the main droplet at the head can be restrained. Thus, a high effect can be given if the contact face between the individual liquid chamber 1 and the rear-side common liquid chamber 43 is wider as much as possible. That is, in the example 3, the choked portion is not provided in the first opening 1c such that the contact area between the individual liquid chamber 1 and the common liquid chamber 43 becomes maximum.
Incidentally, when the choked portion was provided, the threshold of the main droplet speed by which the separated minute droplet was generated at the head was lowered. In particular, when the nozzle diameter was φ10 μm or less, the threshold of the main droplet speed by which the separated minute droplet was generated at the head was lowered to be lower than 5 m/s, and the ink discharge enabling the stable impact could not be performed.
Subsequently, the inkjet head according to the example 4 will be described. In the example 4, the inkjet head illustrated in
Here, the method illustrated in
Next, the individual liquid chamber 1 was formed on the piezoelectric substrate 24. At this time, the thickness of the dicing blade was 50 μm, the diameter of the dicing blade was φ64 mm, and the diamond abrasive grains of #1600 were used. Further, the dicing saw “DAD 6240 Fully Automatic Dicing Saw” (1.2 kW spindle) manufactured by DISCO Corporation was used as the dicing device. The rotation speed of the dicing blade was set to 20000 rpm, and the stage transport speed was set to 0.2 mm/s. The depth of the individual liquid chamber 1 was 300 μm, and the pitch of the plurality of individual liquid chambers 1 was 254 μm. In the example 4, the 100 individual liquid chambers 1 were aligned.
Subsequently, as illustrated in
The dummy chamber 2 was formed in the same manner as that in the example 3. Besides, the processing of the extraction electrode groove 7, the processing of the signal electrodes 14 and 15, the plating elimination of the unnecessary portions, the processing of the dividing groove 19, the processing of the clearance groove 6, and the processing of the nozzle plate 30 were the same as those in the example 3.
In
In the example 4, the same ink as that in the example 3 was used as the ink for the inkjet head 100A. The ink was introduced from the ink supply port 41 of the manifold 40 through the Tygon™ tube. Then, the state that the minute droplet was generated from the main droplet at the head was evaluated based on the discharge observation result according to the manner same as that in the example 3.
As well as the example 3, the maximum main droplet speeds at this time are shown by Table 3. In particular, as the industrial inkjet head, the speed of the main droplet of 5 m/s or more is necessary in consideration of impact accuracy.
Also, in the example 4, it can be understood from Table 3 that, when the diameter of the nozzle was φ5 μm or more, the normal discharge in which the minute droplet was not separated at the head could be achieved even if the discharge speed of the main droplet was 5 m/s or more (good). On the other hand, when the diameter of the nozzle was φ4 μm or less, the stable discharge could not be achieved and thus the nozzle was in the no discharge state (no good).
That is, in the individual liquid chamber having the shear-mode constitution, with respect to the diameters φ5 μm to φ15 μm of the nozzle, the effect of the example 4 in which the two contact faces with the common liquid chamber positioned on the rear side of the nozzle were provided could be confirmed.
In the above example 3, the effect was confirmed in regard to the ratio L1/L2 of the length L1 of the counterbore portion 12c (the second opening 1d) in the longitudinal direction A2 to the length L2 of the individual liquid chamber 1 in the longitudinal direction A2. That is, this example was performed in the same manner as that in the example 3 except for the ratio of the length of the counterbore portion 12c in the longitudinal direction.
Also, the matters same as those in the example 3 were evaluated. The evaluation result obtained on condition that the maximum speed at which the minute droplet was generated at the head in the state that the counterbore portion was not provided was V and the increase (effect) in the maximum speed was ΔV is shown in
That is, if it is assumed that the length of the second opening 1d in the longitudinal direction A2 is L1 and the length of the individual liquid chamber 1 in the longitudinal direction A2 is L2, the effect of restraining the minute droplets becomes remarkable when L1/L2 is within the range of 0.2 to 0.7.
Subsequently, the inkjet head according to the example 6 will be described. In the example 6, the inkjet head illustrated in
First, the method illustrated in
Next, as illustrated in
The dummy chamber 2 was manufactured in the same manner as that in the example 3. Besides, the processing of the extraction electrode groove 7, the processing of the signal electrodes 14 and 15, the plating elimination of the unnecessary portions, the processing of the dividing groove 19, the processing of the clearance groove 6, and the processing of the nozzle plate 30 were the same as those in the example 3.
As illustrated in
Then, the partitions provided on the first substrate 11 and the second substrate 12 were aligned and bonded together. After then, as the liquid chamber portion 43B of the common liquid chamber 43, the counterbore portion 11c was formed below the individual liquid chambers 1 of the first substrate 11 by the dicing blade processing. At this time, after the processing region was filled with the wax for reinforcement to prevent damage of the partitions caused by contact with the common liquid chamber, the dicing blade processing was performed. The contact length with the individual liquid chamber was set to 0.5 times of the total length of the individual liquid chamber. Incidentally, the bonding processing for the flexible substrate 50 was the same as that in the example 1. Finally, as illustrated in
In the example 6, the same ink as that in the example 3 was used as the ink for the inkjet head. The ink was introduced from the ink supply port 41 of the manifold 40 through the Tygon™ tube.
Then, the state that the minute droplet was generated from the main droplet at the head was evaluated based on the discharge observation result according to the manner same as that in the example 3. As well as the example 3, the maximum main droplet speeds at this time are shown by Table 4. In particular, as the industrial inkjet head, the speed of the main droplet of 5 m/s or more is necessary in consideration of impact accuracy.
Also, in the example 6, it can be understood from Table 4 that, when the diameter of the nozzle was φ5 μm or more, the normal discharge in which the minute droplet was not separated at the head could be achieved even if the discharge speed of the main droplet was 5 m/s or more (good). On the other hand, when the diameter of the nozzle was φ4 μm or less, the stable discharge could not be achieved and thus the nozzle was in the no discharge state (no good).
That is, in the individual liquid chamber having the shear-mode constitution, with respect to the diameters φ5 μm to φ15 μm of the nozzle, the effect of the example 6 in which the two contact faces with the common liquid chamber positioned on the rear side of the nozzle were provided could be confirmed.
According to the present invention, since the flow of the liquid from the individual liquid chamber toward the common liquid chamber is large at the time of liquid discharge, the flow of the liquid toward the nozzle is restrained. Consequently, it is possible to reduce the percentage of the change of the discharge speed of the liquid to the pressure applied to the liquid, and it is thus possible to improve the controllability of the discharge speed of the liquid.
Moreover, even if the amount of the droplets to be discharged is made small by reducing the diameter of the nozzle, the minute droplets are not separated and generated before the main droplets, it is thus possible to stably discharge the droplets.
While the present invention has been described with reference to the 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. 2013-018079, filed Feb. 1, 2013, and Japanese Patent Application No. 2013-018080, filed Feb. 1, 2013, which are hereby incorporated by reference herein in their entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-018079 | Feb 2013 | JP | national |
| 2013-018080 | Feb 2013 | JP | national |
