JP2001018383A - Inkjet head - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To propose an electrostatic drive type ink jet head capable of achieving miniaturization and high density. SOLUTION: An ink jet head 1 includes a flow path substrate 2
And the actuator substrate 3. A nozzle groove 4a for forming an ink flow path is formed in the flow path substrate 2.
A groove 11a for forming an ink pressure chamber, a groove 12a for forming an orifice, and a groove 13a for a common ink chamber are formed by anisotropic etching, and individual electrodes 15 and a diaphragm 13 formed by etching a sacrifice layer are formed on the actuator substrate 3. Are formed. Since it is not necessary to form a diaphragm on the flow path substrate 2, the depth of each groove can be arbitrarily determined. By making the groove shallow, the partition walls that partition the adjacent ink flow paths can be made low, its rigidity sufficient, and pressure interference can be prevented. Therefore, it is possible to reduce the size and density of the ink jet head without such adverse effects.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatically driven ink jet head, and more particularly, to an electrostatically driven ink jet head having a structure suitable for miniaturization and high density.

[0002]

2. Description of the Related Art An electrostatically driven ink jet head is
For example, as disclosed in Japanese Patent Publication No. 2-289351, a diaphragm forming a part of an ink flow path communicating with an ink nozzle is opposed to a diaphragm with a predetermined gap. By applying a voltage between the electrodes and the existing electrodes to change the volume in the flow path, ink droplets are ejected from the ink nozzles. A conventional inkjet head of this type is generally configured by laminating three substrates.

That is, as shown in FIGS. 6 and 7, an ink jet head 100 includes an electrode plate 101 made of a glass substrate, a cavity plate 102 made of a silicon substrate, and a nozzle plate 103 made of a silicon substrate, which are formed by anodic bonding or the like. It has a laminated three-layer structure. By performing anisotropic etching from the surface side of the cavity plate 102, a groove 104 for an ink pressure chamber, a groove 105 for a common ink chamber, and a groove 106 for an orifice for communicating these are formed. By controlling the depth of the groove 104 for the ink supply chamber, the groove bottom plate portion serves as a vibration plate 107 that can be elastically displaced in an out-of-plane direction.

A nozzle plate 101 laminated on the surface of the cavity plate 102 has ink nozzles 10
8 are formed. By joining the nozzle plate 101 to the cavity plate 102, the ink pressure chamber 109 communicating with the ink nozzle 108, the common ink chamber 110, and the orifice 111
Are formed.

On the other hand, the electrode plate 101 bonded to the back side of the cavity plate 102 is subjected to isotropic etching from the surface thereof so that
A groove 112 is formed at a portion facing the groove, and an individual electrode 113 is formed at the bottom of the groove. Electrode plate 1
01 is bonded to the back surface of the cavity plate 102 and the sealing material 114 is attached, so that a sealed gap 114 is formed between each individual electrode 113 and the corresponding vibration plate 107.

The vibration plate 107 and the corresponding individual electrode 113
By applying a voltage between them and generating an electrostatic force between them, the volume of the ink pressure chamber 109 changes, and ink droplets are ejected from the ink nozzles 108.

[0007]

In order to achieve the miniaturization and high density of the ink jet head having this configuration, it is necessary to increase the density of the components. However, as the size and density are increased, the partition wall between adjacent ink pressure chambers formed by etching the cavity plate becomes thinner.

In particular, a groove for forming an ink pressure chamber is formed by anisotropic etching, and a diaphragm having desired characteristics is formed by the depth of the groove. It becomes difficult to form a groove having a predetermined depth while keeping the thickness.

As a result, since the partition wall rigidity is reduced, pressure interference (crosstalk) occurs between adjacent ink pressure chambers, and there is a possibility that an appropriate ink droplet ejection operation is hindered.

Further, conventionally, since three plates are joined to each other to form an ink jet head, it is necessary to accurately position these components, and therefore, assembling accuracy is also required. Further, it is necessary to accurately etch grooves and the like for forming ink flow passages in each plate, and it may be difficult to obtain an accurate inkjet head when increasing the density.

[0011] The object of the present invention is to solve the above problems.
An object of the present invention is to propose an ink jet head having a structure capable of easily achieving miniaturization and high density.

[0012]

In order to solve the above-mentioned problems, the present invention forms an ink pressure chamber, an ink nozzle communicating with the ink pressure chamber, and a part of the ink pressure chamber. An electrostatically driven ink jet head having a diaphragm serving as a common electrode and an individual electrode facing the diaphragm via a gap portion has the following configuration. .

That is, the ink jet head of the present invention has first and second substrates. Further, on the surface of the first substrate, the individual electrodes and the diaphragm facing the individual electrodes via the gaps formed by the sacrifice layer etching are formed. Furthermore,
A groove for the ink pressure chamber for forming the ink pressure chamber is formed on the surface of the second substrate. In addition to this, by joining the first and second substrates, the groove for the ink pressure chamber formed on the surface of the second substrate is closed by the first substrate, An ink chamber is formed.

In the ink jet head according to the present invention, a groove for forming an ink flow path portion (ink nozzle, ink pressure chamber) is formed in the first substrate, and an electrostatic actuator portion (vibration plate) performs etching of a sacrifice layer. Utilized on a separate second substrate. Therefore, it is possible to arbitrarily determine the depth of the groove for forming the diaphragm and the ink pressure chamber without considering the thickness of the diaphragm. Therefore, if the groove depth is reduced and the height of the partition wall between the ink pressure chambers is reduced, sufficient partition wall rigidity can be ensured even when the partition wall thickness is reduced.

As a result, even if the size and density of the ink jet head are reduced, pressure interference occurs between adjacent ink pressure chambers due to a decrease in the rigidity of the partition wall between the ink pressure chambers, thereby deteriorating the ink discharge characteristics. Evil effects are prevented. In addition, according to the present invention, the inkjet head can be manufactured by joining the two components of the first and second substrates. Therefore, the manufacturing is easier than the case where the inkjet head is manufactured by stacking three substrates. In addition, the assembly error at the time of assembly can be reduced.

It is preferable that the first and second substrates are joined via a diaphragm formed on the surface of the first substrate.

According to the above configuration, there is no need to remove the joint portion of the diaphragm formed on the surface of the first substrate with the second substrate, and it is not necessary to perform a step of partially etching the diaphragm. And its manufacture becomes easier.

Further, a nozzle hole or a nozzle groove for forming the ink nozzle may be formed on the surface of the second substrate.

In this case, since the nozzle hole or the nozzle groove and the groove for the ink pressure chamber are formed integrally on the second substrate, the positional displacement between the ink pressure chamber and the nozzle hole or the nozzle groove is reduced, and the ink liquid is reduced. Disturbance does not occur in the flow of ink in the ink flow path at the time of drop ejection. Since the flow of the ink in the ink flow path is not disturbed, the flying direction and the amount of the ejected ink droplets are constant, and the print quality can be further improved.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An example of an ink jet head to which the present invention is applied will be described below with reference to the drawings.

FIG. 1 is a schematic perspective view showing the electrostatic drive type ink jet head of the present embodiment in a partially cutaway state, and FIG. 2 is a schematic sectional view taken along the line II-II of FIG. FIG. 3 is a partial sectional view of a portion cut along the line III-III.

First, referring to FIG. 1, the ink jet head 1 of this embodiment includes a flow path substrate 2 (first substrate) made of a semiconductor substrate such as silicon and a glass actuator substrate 3 (second substrate). Substrate) is formed in a two-layer structure by anodic bonding or adhesive bonding. Ink nozzles 4 are opened at regular intervals on the front surface 1a of the ink jet head 1, and ink intake ports 5 and 6 for opening ink supplied from the outside are opened on the rear upper surface. Between these, the terminal portions 7 of the individual electrodes made of ITO or the like are exposed in a number corresponding to the number of the ink nozzles 4, and a common electrode terminal portion 8 is formed at a lateral position thereof. .

The internal structure will be described with reference to FIGS.
Each ink nozzle 4 of the ink jet head 1 communicates with an ink pressure chamber 9, and each ink pressure chamber 9 is separated from each other by a partition 10. Each ink pressure chamber 9 communicates with a common ink chamber 12 via an orifice 11. Ink is supplied to the common ink chamber 12 from the outside via the ink intake ports 5 and 6. A vibrating plate 13 is formed on the bottom surface of each ink pressure chamber 9.
The vibrating plate 13 faces the individual electrode 15 via the closed space 14.

A part of the common ink chamber 12 is defined by a diaphragm 16 which can be elastically displaced in the out-of-plane direction. The diaphragm 16 is for suppressing or absorbing fluctuations in ink pressure in the ink flow path generated due to the ink discharging operation.

The vibrating plate 13 is electrically connected to the common electrode terminal portion 8, and each of the individual electrodes 15 is led out to the outside as an individual electrode terminal portion 7. When a voltage is applied between the diaphragm 13 and each of the individual electrodes 15, an electrostatic force is generated between them and, as a result, the diaphragm 13
Are elastically displaced in an out-of-plane direction, that is, in the vertical direction in FIGS. As a result, the volume of the ink pressure chamber 9 changes, and ink droplets are ejected from the ink nozzle 4 communicating with the ink pressure chamber 9. Since the principle of such ink ejection is known, further description is omitted in this specification.

Here, each of the above-described portions in the ink jet head 1 of the present embodiment is configured as follows. First, in the flow path substrate 2, a nozzle groove 4a for forming an ink nozzle and a nozzle groove 4a for forming an ink pressure chamber are formed on the surface to be joined to the actuator substrate 3 by anisotropic etching such as dry etching or wet etching. A groove 9a, a groove 11a for forming an orifice, and a groove 12a for forming a common ink chamber are formed. Further, a concave portion 16a for forming a diaphragm is formed on the opposite surface of the flow path substrate 2 by dry etching or wet etching.

In this case, a groove 9a for forming an ink pressure chamber formed on the flow path substrate 2 and a groove 11a for forming an orifice are formed.
Is formed vertically or at a constant angle on the (111) plane of single-crystal silicon, so that high-precision grooves 9 can be formed.
a and the grooves 11a can be formed with high density.
A side wall perpendicular to the actuator substrate can be formed by wet etching the (110) wafer, and a side wall having an inclination of 54.7 degrees with respect to the actuator substrate is formed by wet etching with the (100) wafer. can do.

Therefore, in the case of a high-density ink jet head having high responsiveness by reducing the resistance of the flow path, (1)
10) It is desirable that the side wall be formed vertically by wet etching the wafer.

When pressure interference between adjacent ink pressure chambers is prevented, it is desirable to increase the rigidity by wet etching the (100) wafer.

On the other hand, in the actuator substrate 3, each individual electrode 15 is formed on the surface 3a joined to the flow path substrate 2. A diaphragm 13 is also formed on the front surface 3a, and a portion of the diaphragm 13 facing the individual electrode 15 is
Thus, a closed cavity 14 is formed. The voids 14 are formed by sacrifice layer etching. Therefore, the diaphragm 1 facing this gap portion 14
The portion 3 functions as the vibrating portion 13A.

The flow path substrate 2 and the actuator substrate 3 thus configured are laminated on each other by anodic bonding or adhesive bonding. As a result, between these substrates,
Each ink nozzle 4, each ink pressure chamber 9, each orifice 1
1 and a common ink chamber 12 are defined.

When the actuator substrate 3 and the flow path substrate 2 are joined, the diaphragm 13 at the surface 3a to be joined is further removed by etching, and then processed without the intervention of the diaphragm 13. It is also possible. For example, if the diaphragm 13 at the surface 3a where the actuator substrate 3 and the flow path substrate 2 are joined is removed and anodic bonding is performed, the bonding at the time of bonding these substrates can be stabilized and the strength can be improved. Becomes

(Method of Forming Vibrating Portion 13A) Here, the vibrating portion 13A of the vibration plate 13 formed on the surface 3a of the actuator substrate 3 of this embodiment is formed by sacrifice layer etching.

The sacrifice layer etching is performed, for example, in Japanese Patent Application Laid-Open
No. 5,510,374, U.S. Pat.
As described on page 2 of the specification, after forming a sacrificial layer, the sacrificial layer is etched away to form a void. The void portion formed by conventional sacrificial layer etching is an open void provided for modulating the position of the reflection surface of the light valve by electrostatic force. As in the ink jet head 1 of the present example, there has not been proposed a method of using a sacrificial layer etching to form a closed void.

In the present embodiment, for example, the closed space 14 is separated from the diaphragm 13 and the individual electrode 15 by the following method.
It is formed between. Referring to FIG. 3, first, for example, an ITO electrode layer is formed on a glass substrate for forming the actuator substrate 3 by sputtering, and this layer is patterned by photolithography to form each individual electrode 15. Form.

Next, aluminum is vapor-deposited to a predetermined thickness to cover each individual electrode 15 to form a sacrificial layer (a portion corresponding to the void 14 in FIG. 3). An insulating layer 21 made of silicon dioxide is formed on the surface of the sacrificial layer. Thereafter, a diaphragm 13 made of polysilicon having a predetermined thickness is formed so as to cover the insulating layer 21 and the exposed surface of the glass substrate. Thereafter, the sacrificial layer is etched away by an etching solution such as a mixed solution of phosphoric acid, hydrochloric acid, and hydrogen peroxide using an etch hole formed in the diaphragm 13. As a result, the sacrificial layer formation portion becomes a void,
The portion 13A of the vibration plate 13 that has been stacked on the sacrificial layer via the insulating layer 21 becomes a vibrating portion that floats up from the individual electrode 15 by a predetermined gap. Thereafter, an insulating layer 22 made of silicon dioxide is formed on the entire surface of the diaphragm 13.
Further, the portion of the diaphragm forming layer used as an etch hole is also closed, so that the closed void portion 14 is formed.

The material for forming the diaphragm 13 may be platinum or nickel in addition to the above-mentioned polysilicon. By using these metals as the material of the diaphragm 13, it is possible to obtain the diaphragm 13 having higher conductivity, which is convenient for increasing the density of the flow path.

Further, as a material of the insulating layer 21, silicon nitride may be used. When the actuator substrate 3 is formed using these materials, silicon dioxide is used as the sacrificial layer, and hydrofluoric acid is used as the etching solution. In this case, the etching solution can be the same as the etching solution for silicon dioxide, which is the mask of the flow path substrate 2.

(Example of Inkjet Recording Apparatus) FIG. 4 is a schematic configuration diagram showing main components of an inkjet recording apparatus equipped with the inkjet head 1 having the above-described configuration. The inkjet recording apparatus 40 includes a carriage mechanism 42 for reciprocating the inkjet head 1 along a guide rail 41,
And a transport mechanism 45 including a feed roller 44 for transporting the recording paper 43 via the recording position of the recording paper 43. Ink is supplied to the ink jet head 1 from an ink supply unit (not shown) via an ink tube.

Next, FIG. 5 is a schematic configuration diagram showing main components of a line printer in which the ink jet head 1 having the above configuration is mounted as a line head. The line printer 50 of the present embodiment includes a line head 51 arranged so as to cover a recording range, and a transport mechanism 55 including feed rollers 53 and 54 for transporting a recording sheet 52 through a recording position of the line head. And the line head 51
An ink supply mechanism 57 including an ink pipe 56 for supplying ink to the printer and a control circuit (not shown).

It should be noted that the present invention is not limited to the above-described embodiment, and various changes can be made.

For example, in the above embodiment, the nozzle grooves 4a for forming the ink nozzles are formed in the flow path substrate 2, but they may be formed in the actuator substrate 3. When formed in the flow path substrate 2, the nozzle groove 4a and the groove 9a for forming the ink pressure chamber can be integrally formed by a method such as anisotropic etching. The nozzle 4
There is no turbulence in the flow in the ink flow path due to the mutual displacement of the ink pressure chamber 9 and the ink pressure chamber 9, and it is possible to reduce the variation in the flying direction of the ink droplets ejected from the nozzles 4 and the amount of ink. There are effective effects such as being able to obtain an ink jet head of an excellent recording apparatus.

[0043]

As described above, the ink jet head of the present invention is constituted by joining the first substrate and the second substrate, and the first substrate has a groove for an ink flow path. An individual electrode and a vibrating plate having a vibrating portion formed by sacrificial layer etching are formed on the second substrate by anisotropic etching.

Therefore, according to the present invention, since it is not necessary to form a diaphragm on the first substrate, the depth of the groove for the ink flow path to be formed on the first substrate can be arbitrarily set. Therefore,
By making the grooves shallow, the partition walls separating the grooves for forming each ink pressure chamber can be made low. As a result, even when the size and density of the ink jet head are reduced, the rigidity of the partition between the ink pressure chambers can be made sufficient, and pressure interference between the ink pressure chambers can be prevented.

Further, since the ink jet head can be manufactured by joining the two components of the first and second substrates, it is possible to easily manufacture a high precision ink jet head with a small assembly error.

As described above, according to the present invention, it is possible to realize an ink jet head capable of easily achieving downsizing and high density.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an electrostatic drive type inkjet head to which the present invention is applied, with a part thereof being cut away.

FIG. 2 is a schematic sectional view taken along line II-II in FIG.

FIG. 3 is a schematic partial cross-sectional view when cut along the line III-III in FIG. 1;

FIG. 4 is a schematic configuration diagram illustrating an example of an inkjet printer equipped with an inkjet head according to the present invention.

FIG. 5 is a schematic configuration diagram illustrating an example of a line printer equipped with a line head according to the present invention.

FIG. 6 is a schematic configuration diagram showing a cross-sectional configuration of a conventional electrostatically driven inkjet head.

FIG. 7 is a schematic configuration diagram illustrating a planar configuration of the inkjet head of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ink-jet printer 2 Channel board (1st board) 3 Actuator board (2nd board) 4 Ink nozzle 4a Nozzle groove 5, 6 Ink inlet 7 Individual electrode terminal 8 Common electrode terminal 9 Ink pressure chamber 9a Ink Groove for forming pressure chamber 11 Orifice 11a Groove for forming orifice 12 Common ink chamber 12a Groove for forming common ink chamber 13 Vibration plate 13A Vibration portion of vibration plate 14 Void formed by sacrificial layer etching 15 Individual electrode

Claims (3)

[Claims] 1. An ink pressure chamber, an ink nozzle communicating with the ink pressure chamber, a diaphragm serving as a common electrode forming a part of the ink pressure chamber, and a gap with respect to the diaphragm. An electrostatic drive type inkjet head having individual electrodes facing each other through a portion, comprising: a first substrate and a second substrate; and a surface of the first substrate, the individual electrodes and a sacrifice layer. The diaphragm is formed so as to face the individual electrode through the gap formed by etching, and an ink pressure for forming the ink pressure chamber is formed on a surface of the second substrate. A groove for the ink pressure chamber formed on the surface of the second substrate by joining the first and second substrates, the groove for the ink pressure chamber being closed by the first substrate. Grooved in the ink chamber Ink jet head is characterized in that it is formed. 2. The method according to claim 1, wherein the first and second substrates are provided with the first substrate.
2. The ink jet head according to claim 1, wherein said ink jet head is joined via a diaphragm formed on the surface of said substrate. 3. The ink jet head according to claim 1, wherein a nozzle hole or a nozzle groove for forming the ink nozzle is formed on a surface of the second substrate.