JP2000334943A - Ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet recorder in which the ink channels at the opposite ends of a row can have ink ejection characteristics equivalent to the ink drop ejection characteristics at other channels in a row by eliminating abnormal flexure occurring frequently in the diaphragms at the opposite ends of a row of ink channels. SOLUTION: The ink jet recorder has an ink jet head comprising nozzles, ink channels communicating with the nozzles, diaphragms 5 formed at a part of the channel, oscillation chambers 9 formed oppositely to the channel side of the diaphragm 5, and electrodes 17 formed oppositely to the diaphragm 5 on the bottom face of the oscillation chamber 9 wherein the diaphragm 5 is deformed electrostatically by applying an electric pulse between the diaphragm 5 and the electrode 17 and an ink drop is ejected from the nozzle. Sets of the nozzles, channels, diaphragms 15, oscillation chambers 9, and electrodes 17 are arranged in rows at a constant interval in the ink jet recorder and dummy sets of nozzles 4a, channels, diaphragms, oscillation chambers, and electrodes, noncontributive to ejection of ink drop, are arranged at the opposite end parts of the row.

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.

[0002]

2. Description of the Related Art An ink jet head using an electrostatic attraction force for an actuator has been employed. For example, Japanese Patent Application Laid-Open No. 2-289351 discloses such an ink jet head. This inkjet head has a nozzle, an ink flow path communicating with the nozzle, a vibration plate formed in a part of the flow path, and an electrode formed to face the vibration plate via an air gap, An electric pulse is applied between the diaphragm and the electrode, and the diaphragm is deformed by an electrostatic force so that ink droplets are ejected from the nozzles.

[0003]

The actuator including the vibration chamber composed of the vibration plate and the electrode disclosed in the above-mentioned publication usually has a thin film which becomes the vibration plate on the lower surface from the upper side of the equally-spaced grooves formed on the substrate. However, there is a problem that the diaphragms at both ends of the row of actuators formed in this way tend to be greatly different in bending from the other diaphragms in the row. Due to this bending, even if the same electric pulse is applied between the diaphragm and the electrode, only the flow paths at both ends are different from the other flow paths in the ink ejection weight and the ink discharge speed, and print quality is impaired. There was a problem that would. In the case where an adhesive is used for bonding the above substrates, an ink flow path created by bonding another substrate from above the vibration chambers at both ends of the row and the groove formed in the substrate similarly to the vibration chambers At both ends of the row, the area of the adjoining bonded portion is larger than the other, so that there are many cases where the adhesive flows in therefrom, which has a problem that the print quality and the reliability of the head are impaired. .

The present invention has been made to solve such a problem, and the discharge characteristics from the flow paths located at both ends of the row are not different from the discharge characteristics from other flow paths. It is an object of the present invention to provide a high-reliability ink jet recording apparatus with high printing quality that can show the following.

[0005]

According to the present invention, there is provided an ink jet recording apparatus comprising: a nozzle; an ink flow path communicating with the nozzle; a diaphragm formed in a part of the flow path; It has a vibration chamber formed on the side, and an electrode formed on the bottom of the vibration chamber facing the diaphragm, applies an electric pulse between the diaphragm and the electrode, and deforms the diaphragm by electrostatic force In the ink jet recording apparatus having an ink jet head that ejects ink droplets from the nozzles, in the ink jet recording apparatus in which a set of the nozzles, the flow path, the vibration plate, the vibration chamber, and the electrodes are arranged in rows at equal intervals, At both ends of the row, a set of a dummy nozzle, a flow path, a vibration plate, a vibration chamber, and an electrode that does not contribute to the ejection of the ink droplet is arranged. According to the present invention, the dummy diaphragms take over the bending of the diaphragms at both ends of the row of diaphragms that conventionally contributes to the ejection of ink droplets, and the rows of the rows that contribute to ink ejection It is possible to cause the diaphragms at both ends to bend in the same manner as other diaphragms that contribute to ink ejection. In addition, when adhesive is used to join the substrates, the dummy vibration chambers and flow paths serve as breakwaters, even if the adhesive easily flows into the vibration chambers and flow paths at both ends of the row. Can be solved. Therefore, the same ink ejection characteristics and the same ejection speed can be obtained at both ends of the row and the flow paths in other portions, and an ink jet head having excellent print quality and reliability can be obtained.

In this case, a plurality of sets of dummy nozzles, flow paths, diaphragms, vibration chambers, and electrodes may be arranged at both ends of the row. This has the effect of reducing the difference in how the outer diaphragm bends. Also, when bonding substrates with an adhesive, the number of breakwaters will increase,
This has the effect of further reducing the possibility that the adhesive will flow into the vibration chambers and flow paths on the outer contour of the row that contribute to ink ejection.

In this case, a dummy flow path,
The shape of each set of the vibration plate, the vibration chamber, and the electrode is the same as the shape of each of the other flow paths, the vibration plate, the vibration chamber, and the electrodes that contribute to the ink ejection, and the dummy set is used for the ejection of the ink. May be arranged at equal intervals with the set that contributes to the ink ejection. In this case, the condition of the stress applied to the outer diaphragm of the row that contributes to the ink ejection is changed to the stress applied to the other diaphragm that contributes to the ink ejection. Since it can be made closer to the condition, there is an effect that the difference in how to bend can be further suppressed.

In this case, a dummy flow path,
Extending the rows of sets that contribute to ink ejection, each with the same shape of the flow path, diaphragm, vibration chamber, and electrode that contributes to ink ejection Above, it may be arranged at both ends of the row at the same interval as the set that contributes to ink ejection, in which case it is more effective to reduce the difference in the way the diaphragm bends.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail using an embodiment of the present invention.

FIG. 1 is an exploded perspective view of an ink jet head according to an embodiment of the present invention, which is partially shown in a sectional view. 2 is an enlarged view of a portion A of FIG. 1, FIG. 3 is a perspective view of the ink jet head of the embodiment of FIG. 1 after assembly, FIG. 4 is a cross-sectional side view of the ink jet head of the embodiment of FIG. FIG. 5 is a sectional view taken along line AA of FIG. 4. This embodiment shows an example of an edge ejection type in which ink droplets are ejected from a nozzle hole provided at an end portion of a substrate, but a face ejection type in which ink droplets are ejected from a nozzle hole provided in an upper surface portion of the substrate. It may be of the type. The inkjet head 10 of this embodiment has a laminated structure in which three substrates 1, 2, and 3 having a structure described in detail below are stacked and joined.

The intermediate first substrate 1 is a silicon substrate, and has a plurality of nozzle grooves 1 formed at equal intervals in parallel from one end on the surface of the substrate 1 so as to form a plurality of nozzle holes 4.
1 and a recess 12 communicating with each nozzle groove 11 to form a discharge chamber 6 having a diaphragm 5 as a bottom wall;
2, a narrow groove 13 for the ink inlet provided in the rear part
And a recess 14 that forms a common ink cavity 8 for supplying ink to each ejection chamber 6. The ink inlet 13 a is located behind the recess 14.
Is formed with a size smaller than the nozzle hole 4, and also functions as a filter for preventing dust in the ink from entering the head. In addition,
The narrow groove 13 forms the orifice 7 when the first substrate 1 and the third substrate 3 are joined.

Nozzle grooves 11 and recesses 1 formed at equal intervals
2 and the third substrate 3 at both ends of the narrow groove 13.
And a nozzle groove 11a that forms a dummy nozzle hole 4a, a diaphragm 5a, and a discharge chamber 6a to be described later.
And a concave portion 12a are formed. However, since these do not have the purpose of passing the ink, they have no equivalent to the narrow groove 13 communicating with the concave portion 14.

In addition, when the common electrode 17 is applied to the first substrate 1, it is important that the work function of the semiconductor and the metal material as the electrode is large. In this embodiment, titanium is used as the common electrode material. Although platinum or chromium is used as an underlayer and gold is used as an underlayer, the present invention is not limited to this embodiment, and another combination may be used depending on the characteristics of the semiconductor and the electrode material. The diaphragm 5 is formed by doping boron into the first substrate 1 and stopping the etching, and a thin and uniform thickness is obtained.

As shown in FIG. 2, the first substrate 1 has an oxide film 2 having a thickness of about 1 μm on the entire surface except for the common electrode 17.
4 are formed, and when the diaphragm 5 and an individual electrode 21 described later contact each other when the inkjet head is driven,
Functions as an insulating layer for preventing dielectric breakdown, short circuit, and the like.

A borosilicate glass is used for the lower second substrate 2 bonded to the lower surface of the first substrate 1, and a vibration chamber 9 is formed on the upper surface of the second substrate 2. A recess 15 is provided. The recesses 15 are arranged at the same intervals as the recesses 12 so that when they are joined to the first substrate 1, the recesses 15 face the discharge chamber 6 with the diaphragm 5 interposed therebetween.

A vibration chamber 9 is formed by joining the second substrate 2 to the first substrate 1, and gold is sputtered at each position on the second substrate 2 corresponding to the vibration plate 5. The individual electrodes 21 are formed by forming a gold pattern in substantially the same shape as the diaphragm 5. The individual electrode 21 is connected to the lead 2
2 and a terminal portion 23. These electrodes and the like 21,
The materials 22 and 23 may be acidic conductive films such as ITO instead of gold.

Like the recesses 12 on the first substrate 1, the two ends of the row of the recesses 15 on the second substrate are bonded to the first substrate 1 so as to form a dummy vibration chamber 9a to be described later. 1
5a are formed. Also, the individual electrodes 21 are formed on the bottom surface of the concave portion 15a, similarly to the bottom surface of the concave portion 15.

The upper third substrate 3 joined to the upper surface of the first substrate 1 is made of borosilicate glass, like the second substrate 2. By joining the third substrate 3, the nozzle hole 4, the discharge chamber 6, the orifice 7, and the ink cavity 8 are formed.

Next, the first substrate 1 and the second substrate 2 are anodically bonded at a temperature of 270 to 400 ° C. and a voltage of 500 to 800 V, and under the same conditions, the first substrate 1 and the third substrate 3 And an ink jet head is assembled as shown in FIG. After the anodic bonding, the length between the diaphragm 5 and the individual electrodes 21 on the second substrate 2 depends on the depth of the recess 15 and the individual electrodes 21.
And this length is called the gap length G.

After assembling the ink jet head as described above, as shown in FIG. 3 or FIG. 4, wiring (F) is provided between the common electrode 17 and the terminal 23 of the individual electrode 21.
A drive circuit 102 is connected by a PC (Flexible Print Circuit) 101. Wiring 101 and electrode 1
In this embodiment, an anisotropic conductive film is used as a means for bonding to layers 7 and 23. Nitrogen gas is inserted into the vibration chamber 9 and hermetically sealed with an insulating sealant 30. In this embodiment, the vibration chamber 9 is sealed near the terminal portion 23.
In the present embodiment, the ink 103 is supplied from an ink tank (not shown) to the inside of the first substrate 1 through an ink supply pipe 33 and an ink supply container 32 fitted to the rear of the inkjet head. It satisfies 6 mag. Then, as shown in FIG. 4, the ink in the ejection chamber 6 is ejected as ink droplets 104 from the nozzle holes 4 when the inkjet head 10 is driven, and
05 is printed.

The inkjet head 10 is driven by operating the diaphragm 5 by an electrostatic force acting between the electrodes when a voltage pulse is applied between the common electrode 17 and the individual electrode 21 from the drive circuit 102 through the wiring 101. . When the voltage applied between the electrodes is equal, the electrostatic force generated at the moment of the application of the voltage pulse changes depending on the magnitude of the gap length G, so that the gap lengths G on the same head are all made equal. It is desirable.

As in the present embodiment, the bottom of the recess formed as a result of forming the concave portion 12 on the upper surface of the first substrate 1 becomes the diaphragm 5, and the diaphragm 5 is formed above the concave portion 15 formed on the second substrate 2. The first substrate 1 and the second substrate 2 are arranged such that
In the case of a structure in which the diaphragms are attached to each other, there is a tendency that the diaphragms at both ends of an equally-spaced row bend differently from the other diaphragms in the row. Has a value significantly different from the gap length of other parts of
There is a tendency for the response of the diaphragm at both ends of the train to voltage pulses to be different. The reason why this phenomenon occurs is considered as follows.

The joint between the first substrate 1 and the second substrate 2 is a portion other than the diaphragm 5 of the first substrate 1 and the second substrate 2.
However, the vibration plate 5 has the vibration plate 5 on the same plane as the bonding position of the first substrate 1, and the influence of the stress generated when the substrates are bonded is reduced. It is easily accessible. Since the diaphragm 5 and the concave portions 12 and the concave portions 15 that constitute the diaphragm 5 are arranged at equal intervals, the conditions of the stress due to the joining applied to the diaphragm are all except for both ends of the row. Almost equal. On the other hand, at both ends of the row, since the area of the joint in the direction outside the row is larger than that of the other, the stress applied to the diaphragm at both ends of the row is the stress applied to the other diaphragms of the row. This results in a difference in how the diaphragm bends.

A dummy discharge chamber 6a, a dummy vibration plate 5a, and a dummy vibration chamber 9a formed by a concave portion 12a formed on the first substrate 1 and a concave portion 15a formed on the second substrate 2, The difference in how the diaphragms at both ends of the row bend is determined by the dummy diaphragm 5 that does not contribute to the ejection of ink droplets.
a, and as a result, the ejection characteristics of ink droplets ejected from the nozzles at both ends of the row can be improved.

The nozzle groove 11a, which forms the dummy nozzle hole 4a formed on the first substrate 1, does not contribute to the ejection of ink droplets, but if there is no nozzle groove 11a, the first substrate When the first and second substrates 2 are joined,
Since the air cannot escape from 2a, a dummy diaphragm 5
This is necessary because there is a possibility that a may be excessively deflected to affect an adjacent diaphragm via an adjacent substrate joint. Similarly, although the individual electrodes 21 formed on the bottom surface of the dummy vibration chamber 9a formed on the second substrate 2 do not contribute to the ejection of ink droplets, the individual electrodes 21 In the case where anodic bonding is used for bonding, if there is no individual electrode 21 at the same location, the diaphragm 5a and the bottom surface of the vibration chamber 9a will be bonded, and the influence of the excessively deformed diaphragm 5a will cause the adjacent substrate to be bonded. This is necessary because it may extend to the next diaphragm through the section.

In this embodiment, the dummy nozzle grooves 1
Although only one of the recesses 1a, the recesses 12a, and the recesses 15a are arranged at both ends of the row, a plurality of these may be arranged if there is room to arrange them. The difference in how the diaphragm bends is
Although only one at each end is extremely large, the frequency of the deflection is small enough to affect the ejection characteristics, but a slight difference in the deflection may still remain in the rows several rows inside from both ends. If it is desired to suppress the difference in deflection of the diaphragm, a plurality of dummy discharge chambers 6a, diaphragms 5a, and vibration chambers 9a should be arranged at both ends of the row in order to more closely match the condition of the diaphragm inside the row. Is effective.

In this embodiment, the dummy nozzle grooves 1
Although the shapes of the recesses 1a, 12a, and 15a are not mentioned, these are referred to as the nozzle grooves 11, the recesses 12, and the recesses 15a.
And may be arranged at positions equidistant from the nozzle groove 11, the concave portion 12, and the concave portion 15. Again,
Since the condition of the stress applied to the diaphragm in the outer row that contributes to the ejection of the ink droplets can be made completely equal to the stress condition of the diaphragm inside the row, there is a difference in how the diaphragm bends. The factor can be omitted and it is effective.

If there is enough space in the arrangement, the dummy nozzle grooves 11a, 12a and 15a having the same shape as the nozzle grooves 11, 12 and 15 are replaced with the nozzle grooves, 12 and 15a. In this case, the condition of the stress applied to the outermost diaphragm in the row which contributes to the ejection of the ink droplets may be more than that in the above case. Is more effective because the stress condition is closer to

In this embodiment, the anodic bonding is used for bonding the substrates, but the bonding may be performed using an adhesive. In this case, the concave portion 12a formed on the first substrate 1 and the concave portion 15a formed on the second substrate 2 serve as breakwaters of the adhesive flowing from both ends of the wide row of the bonding surface, so that the flow path of the adhesive or This will help prevent inflow into the actuator. The greater the number of the dummy concave portions 12a and concave portions 15a, the more the breakwater is increased, which is effective.

[0030]

As described above, according to the present invention,
Nozzles, channels, diaphragms arranged in rows at equal intervals,
By arranging a dummy nozzle, a flow path, a vibration plate, a vibration chamber, and a set of electrodes outside the set of the vibration chambers and the electrodes, the vibration plates located at both ends of the row conventionally contributing to the ejection of ink droplets can be formed. The dummy deflection that has appeared is passed on to the dummy diaphragm, and the diaphragms at both ends of the row that contributes to ink ejection bend in the same manner as other diaphragms that contribute to ink ejection. Therefore, it is possible to obtain an ink jet head of high print quality having uniform ejection characteristics regardless of position. In addition, when adhesive is used for bonding substrates, the dummy vibration chambers and flow paths serve as breakwaters, even if the adhesive easily flows into the vibration chambers and flow paths at both ends of the row. Therefore, it is possible to obtain the same ink ejection characteristics and the same ejection speed at both ends of the row and the flow paths in the other portions, and thus the ink jet recording apparatus has excellent print quality and reliability. You can get a head.

Further, according to the present invention, since a plurality of sets of the above-described dummy nozzles, flow paths, diaphragms, vibration chambers, and electrodes are respectively arranged, a diaphragm in the outer contour of a row contributing to ink ejection is provided. This makes it possible to obtain the effect of reducing the difference in deflection of the ink jet head, thereby obtaining an ink jet head having higher printing quality. Also, even when the substrates are bonded with an adhesive, the breakwater for the inflowing adhesive is increased, so that the adhesive may flow into the vibration chambers and flow paths in the outer shell of the row that contributes to ink ejection. Is further reduced, and an ink jet head having more excellent reliability can be obtained.

Also, in the present invention, a dummy flow path,
The shape of each set of the vibration plate, the vibration chamber, and the electrodes is the same as the shape of each of the other flow paths, the vibration plates, the vibration chambers, and the electrodes that contribute to ink ejection. Since it is arranged at equal intervals with the set that contributes to ejection, the condition of the stress applied to the outer diaphragm of the row that contributes to ink ejection should be closer to the condition of the stress applied to the other diaphragm that contributes to ink ejection. Therefore, the difference in how the diaphragm bends can be further suppressed, so that an ink jet head with higher printing quality can be obtained.

Also, in the present invention, a dummy flow path,
Extending the rows of sets that contribute to ink ejection, each with the same shape of the flow path, diaphragm, vibration chamber, and electrode that contributes to ink ejection Above, since it is arranged at both ends of the row at the same interval as the set that contributes to ink ejection, the difference in how the diaphragm bends is further reduced, and when an adhesive is used for joining the substrates, the adhesive becomes It is possible to further suppress the ink droplets from flowing into a flow path or a vibration chamber that contributes to the ejection of ink droplets, and it is possible to obtain an ink jet head having excellent print quality and reliability.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an inkjet head according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion A in FIG.

FIG. 3 is a perspective view of the ink jet head of the embodiment of FIG. 1 after assembly.

FIG. 4 is a sectional side view of the inkjet head of FIG. 1;

FIG. 5 is a sectional view taken along the line AA of FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st board | substrate 2 2nd board | substrate 4 Nozzle hole 5 Vibration plate 6 Discharge chamber 9 Vibration chamber 4a Dummy nozzle hole 5a Dummy diaphragm 6a Dummy discharge chamber 9a Dummy vibration chamber

Claims (4)

[Claims] A nozzle, an ink flow path communicating with the nozzle, a vibration plate formed in a part of the flow path, a vibration chamber formed on a side of the vibration plate opposite to the flow path side, An electrode formed on the bottom surface of the vibration chamber so as to face the vibration plate, an electric pulse is applied between the vibration plate and the electrode, and the vibration plate is deformed by electrostatic force. In an ink jet recording apparatus having an ink jet head that ejects ink droplets, the nozzle, the flow path, the vibration plate, the vibration chamber, and the electrode set are arranged in rows at equal intervals. An ink jet recording apparatus, comprising a set of dummy nozzles, flow paths, vibration plates, vibration chambers, and electrodes that do not contribute to the ejection of ink droplets at both ends of the row. 2. An arrangement of the set of the dummy nozzle, the flow path, the vibration plate, the vibration chamber, and the electrode, wherein the set of the dummy which does not contribute to the ejection of the ink droplet is changed to the one which contributes to the ejection of the ink droplet. 2. The ink-jet recording apparatus according to claim 1, wherein a plurality of rows are arranged at both ends of the set of rows. 3. The arrangement of the set of the dummy flow path, the vibration plate, the vibration chamber, and the electrode, wherein the set which contributes to the ejection of ink droplets and the dummy which does not contribute to the ejection of ink droplets at both ends. 2. The ink jet recording apparatus according to claim 1, wherein each of the sets has the same shape, and is arranged at an equal interval from the set which contributes to ejection of ink droplets. 4. An arrangement of the set of the dummy flow path, the vibration plate, the vibration chamber, and the electrode, the discharge of the same shape and the same shape at both ends of the set contributing to the discharge of the ink droplet. 2. The ink jet recording apparatus according to claim 1, wherein a plurality of sets of the dummy which do not contribute to the ink are arranged at equal intervals on the extension of a row of the set which contributes to the ink.