JP2002067303A - Ink jet head and ink jet printer using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet head and an ink jet printer using it which uses electrostatic force for the ink jet head, costs less than the one heretofore in use and is structured to form gaps between thin film moving electrodes and thin film solid electrodes more precisely and uniformly than the one heretofore in use. SOLUTION: An ink jet head is equipped with vibrating plates which constitute one side of an ink liquid chamber, glass-made vibrating plate substrates which posses thin film moving electrodes on the surface of the vibrating plates outside of the ink liquid chamber, and glass-made electrode substrates which possess thin film solid electrodes facing the thin film moving electrodes outside of the ink liquid chamber, and uses electrostatic force. A thin film layer is placed between the vibrating plate substrates and the electrode substrates, and by this thin film layer a gap is created between the thin film moving electrodes and the thin film solid electrodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head utilizing electrostatic force, that is, a thin film movable electrode provided on a vibration plate and a thin film fixed electrode arranged in parallel with a small distance from the vibration plate. The present invention relates to an ink jet head that ejects ink droplets by applying a voltage to a diaphragm to vibrate a diaphragm, and an ink jet printer using the same.

[0002]

2. Description of the Related Art As shown in FIG.
Is formed by a diaphragm 102 having a thin film movable electrode 104a outside the ink liquid chamber 100,
The thin film movable electrode 104a and the thin film movable electrode 104a
And the thin film fixed electrode 106 arranged in parallel to
The positive electrode and the negative electrode are charged to generate electrostatic force, and the diaphragm 102 is displaced as shown by a broken line in the figure, and then restored, so that the ink supplied from the ink supply hole 108 Ink droplet 11 from chamber 100
It is discharged as 0.

Here, the ink-jet head mainly includes a substrate 114 having ink discharge nozzles 112, and an ink liquid chamber 100 formed with the substrate 114.
2, and an electrode substrate 118 having thin-film fixed electrodes 106 arranged in parallel with the thin-film movable electrode 104a of the diaphragm 102 at minute intervals.

A thin film movable electrode 104a and a thin film fixed electrode 106 of an ink jet head utilizing such an electrostatic force are used.
In general, the gap is very small, that is, several μm or less, and the gap distance has a great influence on the ink ejection amount. for that reason,
In order to perform high-performance printing by discharging ink with a uniform discharge amount by providing an ink liquid chamber, a diaphragm, and a thin film fixed electrode corresponding to each of the plurality of ink discharge nozzles, each of the plurality of ink discharge nozzles is required. Thin film movable electrode 1 corresponding to
It is necessary that the gap distance between the thin film fixed electrode 04a and the thin film fixed electrode 106 be accurately and uniformly set without variation.

[0005]

In the ink jet head, as shown in FIG. 3A, the gap between the thin film movable electrode 104a and the thin film fixed electrode 106 is formed on the electrode substrate 1.
It is determined by the depth of the concave portion 120 formed at 18. For example, in the case of a Pyrex (registered trademark) glass substrate, such a concave portion 120 is formed by ion etching (RIE) using a reactive gas, and in the case of a Si substrate, it is formed by wet etching or the like. Therefore, in order to accurately and uniformly set the gap distance between the thin-film movable electrode 104a and the thin-film fixed electrode 106 without variation, it is necessary to perform an etching process using RIE or wet etching with high accuracy.

[0006] Further, in the ink jet head including the substrate 114, the diaphragm substrate 116 and the electrode substrate 118 shown in FIG. 3 (b), the gap distance between the thin film movable electrode 104a and the thin film fixed electrode 106 is reduced. It is determined by the depth of the recess 120 formed in the substrate 116. Therefore, also in this case, the diaphragm substrate 116 is
It is necessary to perform the etching process with high accuracy using, for example, wet etching.

In addition, the thin film movable electrode and the thin film fixed electrode arranged corresponding to a plurality of ink discharge nozzles and ink liquid chambers respectively function independently to discharge ink at a constant discharge amount. In this case, the depths of the concave portions 120 formed on the diaphragm substrate 116 and the electrode substrate 118 corresponding to the respective ink discharge nozzles must be formed uniformly. Therefore, it is necessary to perform a uniform etching process. However, it is difficult to accurately and uniformly form the depth of the concave portion 120 using the above-described RIE or wet etching. Therefore, the thin film movable electrode 10
It is difficult to manage the gap distance between the thin film fixed electrode 4a and the thin film fixed electrode 106 with high accuracy and uniformity.

Further, one of the diaphragm substrate 116 and the electrode substrate 118 shown in FIGS. 3A and 3B is made of a material such as Pyrex glass, and the other substrate is made of a Si substrate. Both substrates are composed of Si substrates. That is, the diaphragm substrate 116 and the electrode substrate 118
Since at least one of them is made of a Si substrate, there is a problem that the cost of the ink jet head is relatively high. On the other hand, since substrates made of glass materials cannot be joined by anodic bonding or the like, both substrates of the diaphragm substrate 116 and the electrode substrate 118 cannot be made of glass materials.

In order to solve the above problems, the present invention provides an ink jet head using electrostatic force,
It is an object of the present invention to provide an ink jet head having a structure in which the cost is lower than in the past and in which the gap between the thin film movable electrode and the thin film fixed electrode is formed more accurately and uniformly than in the past and an ink jet printer using the same. .

[0010]

In order to achieve the above object, the present invention has a diaphragm forming one surface of an ink liquid chamber, and a thin film movable electrode is provided on a surface of the vibration plate outside the ink liquid chamber. A diaphragm substrate made of a glass material provided, and an electrode substrate made of a glass material provided with a thin film fixed electrode facing the thin film movable electrode outside the ink liquid chamber,
An ink jet head that ejects ink from the ink liquid chamber by applying a voltage between the thin film movable electrode and the thin film fixed electrode to vibrate the vibration plate, wherein the vibration plate substrate and the electrode substrate A thin film layer is provided between the thin film layers, and a gap between the thin film movable electrode and the thin film fixed electrode facing the thin film layer is provided by the thin film layer.

Here, the thin film layer is preferably made of a Si thin film, and the diaphragm substrate and the electrode substrate are
Anodically bonded via the thin film layer is preferred. In addition, it is preferable that both surfaces of the diaphragm substrate and the electrode substrate on which the thin film movable electrode and the thin film fixed electrode face each other are flat surfaces, and correspond to the ink liquid chamber and the ink liquid chamber. A plurality of the thin-film fixed electrodes are provided, the thin-film movable electrode forms a common electrode facing the plurality of the thin-film fixed electrodes, and the thin-film layer serves as the common electrode wiring of the common electrode. It is preferably connected to Further, it is preferable that minute projections made of an insulating material are formed on the surface of the thin film movable electrode. The thickness of the thin film layer is preferably 0.05 μm or more and 2 μm or less.

[0012] The present invention also provides an ink jet printer using the above ink jet head.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an ink jet head of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.

FIG. 1A shows a cross-sectional structure of an ink-jet head 10 which is an embodiment of the ink-jet head of the present invention, and FIG.
FIG. 1C shows the configuration of a plane viewed from the cross section taken along the line −A ′, and FIG. 1C shows a simplified configuration of the cross section of the main part of the inkjet head 10 in FIG. In the drawings, the thickness is exaggerated as compared with the actual structure.

The ink jet head 10 includes a substrate 12,
It has a laminated structure in which the diaphragm substrate 14, the electrode substrate 16, and the thin film layer 17 arranged between the diaphragm substrate 14 and the electrode substrate 16 are joined and integrated. An ink discharge nozzle 13 is provided on the substrate 12, and an ink liquid chamber 18 is formed by the substrate 12 and the vibration plate substrate 14.
An ink supply path 20 for supplying ink to the ink liquid chamber 18 is formed. The ink supply path 20 has a plurality of ink liquid chambers 18a, 18b, 18 arranged in parallel as shown in FIG.
The supply path extends in the vertical direction toward the paper surface of FIG. 1A so as to supply the ink to c and the like, and is connected to an ink tank (not shown).

A portion of the diaphragm substrate 14 has a small thickness, and this portion forms a bottom surface of the ink liquid chamber 18, and a diaphragm 19 which is easily deformed by electrostatic force as described later is formed. Such a vibration plate 19 is formed for each ink liquid chamber. In addition, on the lower surface of the diaphragm substrate 14, FIG.
As shown in (b), each ink liquid chamber 18a, 18
A common thin film movable electrode 22 is arranged at b, 18c,... to form a common electrode. The surface of the diaphragm substrate 14 provided with the thin film movable electrode 22, that is, the lower surface of the diaphragm substrate 14 in FIG. 1A is a flat surface. Here, the diaphragm substrate 14 is made of a glass material such as Pyrex glass, and the thin film movable electrode 22 is made of an Si thin film, an electrode made of a conductive metal thin film such as platinum or nickel, or a Si thin film on the conductive metal thin film layer. It may be an electrode having a two-layer structure in which a thin film layer is formed. In the case where the thin film movable electrode 22 has a two-layer structure, a chromium layer which is extremely thinner than the conductive metal thin film layer or the Si thin film layer may be provided in order to improve the adhesiveness.
Further, when the thin film movable electrode 22 is formed of a Si thin film, it may be configured to be integrated with a thin film layer 17 formed of a Si thin film described later.

The thin film layer 17 (gray area in FIGS. 1A, 1B and 1C) is made of a Si thin film, and the gap distance between the thin film movable electrode 22 and the thin film fixed electrode 26 is reduced. Determine.
Here, the thickness of the thin film layer 17 is preferably 0.05 μm or more and 2 μm or less. Here, if the thickness of the thin film layer 17 is smaller than 0.05 μm, the bonding strength and the sealing property when the thin film movable electrode 22 and the thin film fixed electrode 26 are anodic bonded via the thin film layer 17 are reduced, and the thickness is larger than 2 μm. This is because the diaphragm substrate 14 and the electrode substrate 16 are likely to warp.
The thin film layer 17 is made of a Si thin film, and has a function as a joining member when joining the diaphragm substrate 14 made of a glass material and the electrode substrate 16 as described later.

The thin film layer 17 is formed as shown in FIG.
As shown in the gray area in FIG.
18b, 18c,... Are in contact with and electrically connected to the common thin film movable electrode 22, and are configured as a common electrode wiring of the thin film movable electrode 22. Note that the thin film layer 17 is connected to the recording control unit 34 via the terminal 24. Therefore, the thin-film movable electrode 22 is electrically connected to the recording control unit 34. In the present embodiment, the thin film layer 17 is a Si thin film,
The present invention is not limited to this, and any material may be used as long as Pyrex glass forming the diaphragm substrate 14 and the electrode substrate 16 can be bonded to each other with high precision. Is also good.

The thin film movable electrode 2 is provided on the electrode substrate 16 at a minute interval determined by the thickness of the thin film layer 17, for example, at an interval of 1 μm.
The thin-film fixed electrode 26 is disposed so as to face the electrode substrate 2 and terminals 28 (28a, 28b, 28c,...) Of the individual thin-film fixed electrode 26 corresponding to each ink liquid chamber are provided at the end of the electrode substrate 16.
・) Is provided. The terminal 28 is connected to the transmission circuit 30 (30a, 30b, 30c ...) of the recording control unit 34. The surface of the electrode substrate 16 on which the thin film fixed electrode 26 is provided, that is, the upper surface of the electrode substrate 16 in FIG. 1A is flat, and the gap between the thin film movable electrode 22 and the thin film fixed electrode 26 is thin. 17 is determined.
In this embodiment, the diaphragm substrate 14 and the electrode substrate 16 have a surface on the side where the thin film movable electrode 22 and the thin film fixed electrode 26 face each other, that is, the surface of the diaphragm substrate 14 on the side including the thin film movable electrode 22. The surface of the electrode substrate 16 on the side provided with the thin film fixed electrode 26 is flat, but at least the gap between the thin film movable electrode 22 and the thin film fixed electrode 26 is determined by the thickness of the thin film layer 17. As far as possible, a concave portion may be formed in a part of the surface on the opposite side of the diaphragm substrate 14 and the electrode substrate 16. Here, the electrode substrate 16 is made of a glass material such as Pyrex glass, and the thin film fixed electrode 26 is an electrode made of a Si thin film or a conductive metal thin film such as platinum or nickel, or a Si thin film on the conductive metal thin film layer. An electrode having a two-layer structure in which a layer is formed may be used. When the thin film fixed electrode 26 has a two-layer structure, a chromium layer having a thickness much smaller than that of the conductive metal thin film layer or the Si thin film layer may be provided in order to improve the adhesiveness.

Further, as shown in FIG. 1 (c), the surface of the thin film movable electrode 22, the microprojection stopper 29 made of an insulating material such as SiO ₂ is formed, even if the displacement increases the vibration plate 19 The thin-film movable electrode 22 and the thin-film fixed electrode 26 are configured so as not to be short-circuited by contact. The height of the minute projections is about half or more of the gap distance between the thin-film movable electrode 22 and the thin-film fixed electrode 26, and more preferably about two-thirds of the gap distance.

The recording control unit 34 includes a terminal 24 and a terminal 2
8 includes a control circuit 32 and a transmission circuit 30 to which a predetermined control voltage V is applied to the terminal 28 in a pulsed manner.
On the other hand, the terminal 24 is grounded so that a potential difference is generated between the thin film movable electrode 22 and the thin film fixed electrode 26. Thin film movable electrode 22 and thin film fixed electrode 26 having a potential difference
Because of having conductivity, they are charged to different polarities, and as a result, an electrostatic force acts between the electrodes, and the diaphragm 19 is deformed so as to be convex downward. At this time, ink is supplied from the ink supply path 20 into the ink liquid chamber 18. On the other hand, when the potential difference is released, the diaphragm 19 is restored and the ink liquid chamber 18 is restored.
The internal pressure is rapidly increased, and ink droplets are ejected from the ink ejection nozzles 13.

First, the ink jet head 10 is manufactured by first forming the substrate 12 and the diaphragm substrate 1 made of a glass material.
The well-known wet etching and dry etching are applied to the electrode substrate 16 made of the glass substrate 4 and a glass material to be processed into a desired shape. Thereafter, a Si thin film having a thickness of 0.05 μm or more and 2 μm or less is formed on the electrode substrate 16 by a known sputtering method, and a resist is formed thereon by a known method. Thus, a resist pattern is created. This pattern determines the shape of the thin film layer 17 shown in FIG.
Thereafter, the Si thin film is subjected to an etching process. In a portion where the thin film layer 17 on the electrode substrate 26 is removed by etching,
The thin-film fixed electrode 26 and the terminal 28 are attached using a known sputtering method, a photolithographic etching technique, or the like. On the other hand, the thin-film movable electrode 22 is formed on the diaphragm substrate 14 by using a known method such as a sputtering method or a photolithographic etching technique, and thereafter, the fine projection stopper 29 is formed on the surface of the thin-film movable electrode 22. Thereafter, the diaphragm substrate 14 and the electrode substrate 16 on which the thin film layer 17 is formed are joined by anodic bonding. For example, while heating at 300 ° C., the thin film layer 17 is used as an anode,
Bonding is performed by applying a DC voltage of V for 5 minutes. Further, the substrate 12 is joined to the diaphragm substrate 14.

Here, the thin film layer 17 made of a Si thin film is
Since the thin film layer 17 is provided by the sputtering method or the like, the thickness of the thin film layer 17 can be formed more accurately and uniformly than the conventional processing accuracy when etching the diaphragm substrate 116 and the electrode substrate 118. Therefore, the gap distance between the thin-film movable electrode 104a and the thin-film fixed electrode 106 can be accurately and uniformly formed. Further, the diaphragm substrate 1
When the substrate 4 and the electrode substrate 16 are joined, the glass substrates that cannot be joined, that is, the diaphragm substrate 14 and the electrode substrate 16 can be anodic-joined through the thin film layer 17 made of a Si thin film. The head can be composed of a diaphragm substrate 14 and an electrode substrate 16 made of a glass material. As a result, the cost is reduced as compared with the conventional ink jet head having the diaphragm substrate 116 and the electrode substrate 118 using the Si substrate.

The ink jet head of the present invention
In this configuration, the diaphragm substrate and the electrode substrate are made of a glass material and are integrally joined via a thin film such as a Si thin film. However, the diaphragm substrate and the electrode substrate are made of a Si substrate, and the thin film is made of glass. Head structures are also possible. However, in the case of this head structure, a SiO.sub.
A conductive metal thin film or a semiconductor thin film as an electrode must be formed on the insulating layer of ₂ etc., which complicates the structure of the thin film fixed electrode, or a diaphragm which is more expensive than glass Since it is used for both the substrate and the electrode substrate, there is a disadvantage that the cost is increased.

An example in which such an ink jet head 10 is applied to an ink jet printer will be described. FIG. 2 shows an ink jet printer 50 using the ink jet head 10. The inkjet printer 50 is a line head in which the inkjet heads 10 are arranged in one direction with a plurality of ink ejection nozzles 13 that eject ink beyond the length of at least one side of a recording medium P such as recording paper. It has a recording section 52, a supply section 54, a preheating section 56, and a discharge section 58.

The supply unit 54 includes a pair of transport rollers 60 and 6
2 and guides 64 and 66, and the recording medium P
The sheet is conveyed upward from the lateral direction by the supply unit 54 and supplied to the preheating unit 56.

The preheating section 56 includes a conveyor 68 including three rollers and an endless belt, and a conveyor 6.
8, a pressure roller 70 pressed against the endless belt from outside, a heater 72 pressed against the pressure roller 70 from inside the conveyor 68, and an exhaust fan 74 for exhausting the inside of the preheating section 56. Such a preheating section 56
Is for heating the recording medium P prior to recording by ink jet, thereby promoting drying of the ink ejected on the recording medium P, and realizing high-speed recording.
Is transported from the recording surface side by the heater 72 and transported to the recording section 52 while being nipped and transported by the conveyor 68 and the pressure roller 70.

The recording section 52 includes a recording head section 76, a recording control section 34, and a recording medium transport section 78.
And the ink tank 77, and the inkjet head 10 is connected to the recording control unit 34. The inkjet head 10 is a line head in which a plurality of ink ejection nozzles 13 for ejecting ink droplets are arranged over a length exceeding at least one side of a recording medium P of the maximum size targeted by the inkjet printer 50. The nozzles 13 are arranged vertically in the plane of FIG. Therefore, the inkjet head 10 does not scan in the direction perpendicular to the plane of FIG.
It is recorded at once over the entire recording width. Recorder 5
The recording medium P recorded in 2 is conveyed and discharged by discharge rollers 92 and 94.

Such an ink jet printer 50
Is equipped with the above-described ink jet head 10, the amount of ink droplets ejected from the plurality of ink ejection nozzles 13 is uniform, and high-quality images and the like can be recorded. Note that the inkjet head 10 of the inkjet printer 50 is not limited to a line head, and may be a serial type inkjet head that scans the inkjet head 10 in a direction orthogonal to the direction in which the recording medium P is transported.

The ink jet head of the present invention and the ink jet printer using the same have been described in detail. However, the present invention is not limited to the above embodiment, and various improvements and modifications can be made without departing from the gist of the present invention. Of course, changes may be made.

[0031]

As described above in detail, in an ink jet head utilizing electrostatic force, a thin film is provided between a diaphragm substrate made of a glass material and an electrode substrate, so that the two substrates can be bonded by anodic bonding or the like. Bonding is possible, and an ink jet head can be composed of a vibrating plate substrate and an electrode substrate made of a glass material. The cost is reduced as compared with a conventional ink jet head using a Si substrate as a vibrating plate substrate and an electrode substrate. Can be. Further, the gap between the thin-film movable electrode and the opposed thin-film fixed electrode is set such that the diaphragm substrate having the thin-film movable electrode and the electrode substrate having the thin-film fixed electrode are S
Since it is formed by bonding via a thin film such as an i-thin film, the gap between the thin-film movable electrode and the thin-film fixed electrode can be formed more accurately and uniformly than in the related art. Further, since the ink jet printer of the present invention uses the above ink jet head, the ink ejection amount becomes uniform, and high-quality images and the like can be recorded.

[Brief description of the drawings]

FIG. 1A is an explanatory view including a schematic cross section of one embodiment of an ink jet head of the present invention, and FIG. 1B is a plan view taken along a line AA ′ of FIG. 1A. It is an explanatory view including a drawing, and (c) is an explanatory view showing a schematic cross section of a main part of the ink jet head shown in FIG.

FIG. 2 is a configuration diagram illustrating a schematic configuration of an embodiment of the inkjet printer of the present invention.

FIGS. 3A and 3B are explanatory views showing a schematic cross section of a conventional inkjet head.

[Explanation of symbols]

 Reference Signs List 10 inkjet head 12, 114 substrate 13, 112 ink discharge nozzle 14, 102 diaphragm substrate 16, 118 electrode substrate 17 thin film layer 18, 100 ink liquid chamber 20 ink supply path 22, 104a thin film movable electrode 24, 28 terminal 26, 106 Thin film fixed electrode 29 Micro projection stopper 30 Transmission circuit 32 Control circuit 34 Recording control unit 50 Inkjet printer 52 Recording unit 54 Supply unit 56 Preheating unit 58 Discharge unit 120 Concave portion

Claims (8)

[Claims] A vibrating plate forming one surface of an ink liquid chamber, a vibrating plate substrate made of a glass material having a thin film movable electrode provided on a surface of the vibrating plate outside the ink liquid chamber; An electrode substrate made of a glass material provided with a thin film fixed electrode so as to face the thin film movable electrode,
An inkjet head that ejects ink from the ink liquid chamber by applying a voltage between the thin-film movable electrode and the thin-film fixed electrode to vibrate the vibration plate, wherein the vibration plate substrate and the electrode substrate An ink-jet head, wherein a thin film layer is provided between the thin film layers, and the thin film layer forms a gap between the thin film movable electrode and the opposed thin film fixed electrode. 2. The ink jet head according to claim 1, wherein said thin film layer is made of a Si thin film. 3. The ink jet head according to claim 1, wherein said diaphragm substrate and said electrode substrate are anodically bonded via said thin film layer. 4. The ink jet head according to claim 1, wherein both surfaces of the diaphragm substrate and the electrode substrate on which the thin film movable electrode and the thin film fixed electrode face each other are flat. . 5. A thin-film fixed electrode provided in correspondence with the ink liquid chamber and the ink liquid chamber, wherein the thin-film movable electrode forms a common electrode facing the plurality of thin-film fixed electrodes, 2. The thin film layer is connected to the thin film movable electrode as a common electrode wiring of the common electrode.
5. The inkjet head according to any one of items 1 to 4, 6. The ink jet head according to claim 1, wherein minute projections made of an insulating material are formed on a surface of said thin film movable electrode. 7. A thin film layer having a thickness of 0.05 μm or more and 2 μm or more.
The inkjet head according to claim 1, wherein m is equal to or less than m. 8. An ink jet printer using the ink jet head according to claim 1.