JPH06328682A - Ink jet printing head - Google Patents

Abstract

PURPOSE:To eliminate the cross talk between adjacent nozzles and to efficiently transmit the force generated by piezoelectric elements to the emission of ink droplets by integrating first and second substrates by the fixing member arranged in the vicinity of the piezoelectric elements. CONSTITUTION:A first substrate 110 has a large number of piezoelectric elements 112 arranged to the surface thereof and a second substrate 116 has passages formed thereto in the order of nozzles 117, pressure chambers 118, supply ports 119 and a rervoir 120 from the end surface thereof. The piezoelectric elements of the first substrate 110 are arranged through a vibration plate 130 corresponding to the pressure chambers 118 of the second substrate in a ratio of (1:1) to constitute an ink jet printing head. The signal electrodes 115 fixed and electrically connected to the signal electrodes 141 of a base stand 115 are provided to one surface of the piezoelectric elements 112 formed on the first substrate 110.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head of an ink jet printer which discharges ink droplets in response to a print signal to form an ink image on a recording medium such as recording paper.

[0002]

2. Description of the Related Art As described above, a piezoelectric element formed by a plurality of grooves on a first substrate and a plurality of pressure chambers communicating with nozzles, supply ports and reservoirs formed as grooves on a second substrate. The ink jet type print head, which corresponds to and is stacked, is a technique generally known as a recording head of a so-called on-demand type ink jet printer in which ink droplets are ejected according to a print signal.

In recent years, ink jet printers are required to have high printing quality and downsizing of the head, and accordingly high density arrangement of piezoelectric elements and pressure chambers is required. Japanese Patent Application Laid-Open No. 3-247453 and Japanese Patent Application Laid-Open No. 3-284
In Japanese Patent Laid-Open No. 950 and Japanese Patent Laid-Open No. 4-64448,
A high-density head is realized with a basic structure in which slits are provided in the piezoelectric body, parallel flow paths are provided through the diaphragm corresponding to the piezoelectric elements formed between the slits, and the upper plate is placed above it. Trying to.

A prior art Japanese Patent Laid-Open No. 3-247453 will be described with reference to FIG. In the first substrate 10, the piezoelectric body 11 (blocked state shown by the dotted line in the figure) is laminated on the base 15, and then a continuous slit 22 parallel to the surface is provided,
A plurality of piezoelectric elements 12 are formed between the slits 22. On the other hand, the second substrate 16 is integrally formed with a flow path on the surface, which communicates with the nozzle 17, the pressure chamber 18, the supply port 19, and the reservoir 20 from the end face. Then, the first substrate 10 and the second substrate 16 are bonded via the diaphragm 30. In this structure, the base 15 that constitutes the first substrate 10 needs to have sufficiently high rigidity with respect to the piezoelectric element 12.

Further, the prior art of Japanese Patent Laid-Open No. 3-284950.
The publication will be described with reference to FIG. The first substrate 10 has continuous slits 22 parallel to the surface of the piezoelectric body 11, and a plurality of piezoelectric elements 12 are formed between the slits 22. On the other hand, the second substrate 16 forms a pressure chamber 18 communicating with the nozzle 17 on its surface. Then, the first substrate 10 and the second substrate 16 are bonded via the diaphragm 30. In this structure, the vibrating plate 30 has a partial elastic body thickness smaller in the non-bonded portion in the vicinity 31 than in the bonded portion between the piezoelectric element 12 and the second substrate 16.

A prior art Japanese Patent Laid-Open No. 4-64448 will be described with reference to FIG. The first substrate 10 is provided with continuous slits 22 parallel to the surface of the piezoelectric body 11 (see FIG. 6) having an active portion 13 whose thickness is displaced and an inactive portion 14 whose thickness is not displaced, and a plurality of piezoelectric elements are provided between the slits 22. Element 12
Is formed. On the other hand, the second substrate 16 is formed by joining the nozzle 23, the parallel flow passage 21, and the member 23 forming the communicating flow passage which becomes the reservoir 20 from the end face to the surface and the upper plate 24. Then, the first substrate 10 and the second substrate 16 are directly bonded. In this structure,
The second substrate 16 is bonded to the inactive portion 14 of the piezoelectric element 12 in which the active portion 13 and the inactive portion 14 are integrated.

[0007]

Reducing the size of the recording head,
As the density is increased, the dimensions of the piezoelectric element, the nozzle, the pressure chamber, the supply port, and the flow path that communicates with the reservoir become smaller, and the space for providing the functional structural member for reinforcement becomes smaller. The conventional technique has a structure in which the second substrate 16 is easily deformed, and crosstalk between adjacent nozzles and dispersion of the piezoelectric element generation force occur. The crosstalk is an abnormal phenomenon at the time of ink droplet ejection. One example is a phenomenon in which an ink droplet is ejected from another nozzle even though any one of a plurality of consecutive nozzles has been driven. In another example, although a plurality of nozzles are driven all at once and any one of them is not driven,
This is a phenomenon in which ink droplets are continuously ejected from the nozzle.

In the prior art shown in FIG. 5, the piezoelectric element 12
Since a plurality of piezoelectric elements 12 are laminated on the base 15 having a sufficiently high rigidity, mutual interference of vibrations between adjacent piezoelectric elements 12 is eliminated, and crosstalk transmitted through the base 15. However, since the first substrate 10 and the second substrate 16 are bonded via the vibration plate 30 floating on the ink in the pressure chamber 18, the thickness displacement of the piezoelectric element 12 is affected by the ink. The second substrate 16 is transmitted to the second substrate 16 and is deformed as shown in FIG. 8, so that crosstalk is transmitted between the nozzles 17 via the second substrate 16. As the number of continuous piezoelectric elements 12 and pressure chambers 18 increases, the crosstalk transmitted through the second substrate 16 near the center of the continuous nozzles 17 becomes more remarkable.

Further, in the prior art shown in FIG. 6, the first substrate 10 and the second substrate 16 are not directly fixed to each other in a floating state in a portion where the piezoelectric element 12 and the pressure chamber 18 correspond to each other as described above. Yes, and the piezoelectric element 1 of the diaphragm 30
Since the thickness of the elastic body in the vicinity 31 of the joint between the second substrate 16 and the second substrate 16 is thin, the thickness displacement of the piezoelectric element 12 is transmitted to the second substrate 16 via the ink, and the second substrate 16 Shows a behavior (see FIG. 8) in a direction that easily separates from the first substrate 10, crosstalk transmitted through the above-mentioned second substrate 16 occurs, and the thickness displacement of the piezoelectric element 12 is efficient. It is not well transmitted to the ink droplet ejection.

Further, in the prior art shown in FIG. 7, the inactive portion 14 which is a part of the piezoelectric element 12 prevents the thickness displacement of the active portion 13 and absorbs the thickness displacement of the active portion 13 to inactivate the thickness displacement. Despite being 14, the thickness displacement will occur. Therefore, the second substrate 16 bonded to the inactive portion 14
Shows a behavior in a direction in which it easily separates from the first substrate 10, and causes the same problem as described above.

[0011]

An ink jet print head of the present invention has a reservoir and a supply port communicating with the reservoir on the same plane, a nozzle on one wall surface, and another wall surface on the other wall surface. An inkjet including a second substrate in which a plurality of pressure chambers each having a vibration plate are arranged in parallel, and a first substrate in which piezoelectric elements having a one-to-one correspondence with the pressure chambers and having displacement surfaces connected to the vibration plate are arrayed and fixed. Type print head, in the vicinity of the piezoelectric elements in the vertical direction in which a plurality of the piezoelectric elements are arranged,
A member is arranged so as to fill a gap between the first substrate and the second substrate and have a gap with the piezoelectric element.

The member is provided on the second substrate,
The active portion that is fixed to the supply port portion adjacent to the pressure chamber via the vibration plate, and that the thickness-displaced active portion of the piezoelectric element is in the vertical direction in which a plurality of the piezoelectric elements are arranged, The vibration plate for transmitting the thickness displacement of the piezoelectric element to the pressure chamber is arranged in the range of
It is characterized in that a portion of the pressure chamber that comes into contact with ink has a low rigidity and a portion near the periphery of the aforesaid portion has a high rigidity.

[0013]

EXAMPLES The ink jet print head according to the present invention will be described in detail below with reference to examples. FIG. 1 is an exploded perspective view for explaining the configuration of an ink jet type print head according to an embodiment of the present invention. FIG. 2 is a sectional view taken along line AA of FIG. FIG. 3 is a partial cross-sectional view that passes through the pressure chamber in the direction in which a plurality of piezoelectric elements are arranged, and is a diagram for explaining the driving method. FIG. 4 is a diagram for explaining the manufacturing method of the present invention.

In these figures, reference numeral 110 denotes a first substrate on which a plurality of piezoelectric elements 112 are arranged. 116
Is the second substrate, and the nozzle 117, the pressure chamber 11
A flow path is formed in the order of 8, the supply port 119, and the reservoir 120. An ink jet print head is configured by arranging the piezoelectric elements 112 of the first substrate 110 via the vibrating plate 130 in one-to-one correspondence with the pressure chambers 118 of the second substrate 116.

An ink jet print head manufactured according to the present invention will be described with reference to FIGS. 1 and 2. First,
The configuration of the first substrate 110 will be described in detail.

The piezoelectric element 112 formed on the first substrate 110 has a signal electrode 141 of a base 115 on one side surface.
A signal electrode 151 fixedly connected to and electrically connected to the common electrode 142 is provided, and a common electrode 152 fixedly connected to and electrically connected to the common electrode 142 is provided on the other side surface. The signal electrode 151 and the common electrode 152 are respectively the signal electrode 141 of the base 115.
And to the drive circuit via the common electrode 142.

The piezoelectric element 112 has a comb-shaped structure, and a plurality of piezoelectric elements 112 are formed in parallel. These are groove-processed with, for example, a dicing saw, a wire saw, or the like, and a full cut for cutting the piezoelectric element 112 to the surface of the base 115 or a half cut that does not reach the base 115 is performed. As the material of the piezoelectric element 112, lead zirconate titanate (PZT) is used here, and either a single-layer piezoelectric element or a laminated piezoelectric element can be used.

In this embodiment, the signal electrode 1 of the piezoelectric element 112
Reference numeral 51 denotes each piezoelectric element 11 by fixing the piezoelectric body to the base 115 and cutting the surface of the base 115 by the cutting means.
It is formed as two signal electrodes. Since the common electrode 142 is divided at the same time, the copper foil and the conductive adhesive (paste)
It can be easily formed by electrically connecting to the common electrode 152 of the plurality of piezoelectric elements 112 and a part of the common electrode 142 on the base 115 by using, for example.

As shown in Table 1, the main part dimensions of the first substrate 110 in this embodiment are a high density array.

[0020]

[Table 1]

Next, the structure of the second substrate 116 will be described in detail.

The second substrate 116 has a groove for forming the pressure chamber 118, a nozzle 117 and a supply port 11 adjacent to the groove.
9, a reservoir 120 communicating with 9 is integrally formed. The second substrate 116 can be easily molded by injection molding of synthetic resin, for example. As other techniques, it is formed by molding by etching with a photosensitive resin, or by separately molding and fixing the flow path forming portion of the second substrate 116 and other portions by pressing or etching. . In this example, the second substrate 116 was manufactured by etching a silicon wafer which is easy to form a groove and by injection molding a synthetic resin. The nozzle 117 can be formed not only as a groove on the surface but also as a hole on the side surface of the second substrate 116 by an excimer laser.

Table 2 shows the main part dimensions of the second substrate 116 in this embodiment.

[0024]

[Table 2]

The structure of the diaphragm 130 will be described in detail.

Since the vibrating plate 130 is a member that forms each flow path together with the second substrate 116, it covers the entire surface of the second substrate 116. And it is indispensable to have vibrating elasticity as a constituent material. For example, the diaphragm 130 can be formed by casting polyimide in a thin film shape on a stainless foil and a copper foil having a thickness accuracy and etching away the metal only in a portion where elasticity is required. As another technique, it is manufactured by two-step electroforming. First, an elastic thin film is formed, and a resist is applied to the part where elasticity is required, and the other part is
It can be formed by increasing the film thickness by electroforming of the step.
Since the above manufacturing methods are all formed by the optical method, the member accuracy can be controlled very stably.

The operation of the print head of this embodiment will be described with reference to FIG. FIG. 3 is a partial cross-sectional view of an ink jet type print head utilizing a displacement parallel to the direction of an applied electric field of a piezoelectric element as one embodiment of the present invention. A signal is applied from the drive circuit to the signal electrode 141, and the piezoelectric element 112
Is transmitted to the signal electrode 151. The common electrode 152 of the piezoelectric element 112 connected to the common electrode 142 is always at a common potential. A piezoelectric effect occurs due to a change in potential at the signal electrode 151 due to signal application, and the piezoelectric element 112 is displaced in thickness in the direction of the pressure chamber 118 with respect to the base 115. Based on this operation, the ink jet print head according to the present invention ejects ink droplets from the nozzle 117.

As shown in FIG. 3A, the piezoelectric element 112 displaces the vibrating plate 130 fixed to the piezoelectric element 112 in the C direction to press the vibrating plate 130, thereby causing a change in the volume of the pressure chamber 130, and the dynamic pressure of the ink ejection. And the ink droplets are generated in the nozzle 117.
Is discharged more. Further, as the next operation, as shown in FIG. 3B, the piezoelectric element 112 displaces the vibration plate 130 fixed thereto in the pressing release D direction, whereby the pressure chamber 130 is moved.
Changes in the volume of the ink, causing dynamic pressure in the ink supply,
Ink is supplied from the reservoir 120 into the pressure chamber 118 through the supply port 119. By selectively transmitting a signal to the piezoelectric element 112 that comes into contact with the pressure chamber 118 communicating with the nozzle 117 required for printing in the above operation, an ink image can be formed on a medium such as paper.

The manufacturing method of this embodiment and the features of the present invention will be described with reference to FIG. As shown in FIG. 1, the ink jet print head of this embodiment has a first substrate 110 forming a plurality of piezoelectric elements 112, a piezoelectric element 112, and a pressure chamber 118.
The vibrating plate 130 and the pressure chamber 1 whose elastic portion is the portion that contacts the pressure chamber 1
The second substrate 116 forming the reservoir 117 communicating with the nozzle 117 and the supply port 119 adjacent to the nozzle 18.
It is manufactured by stacking and joining.

First substrate 110 and second substrate 1 of the present invention
Fixing member 101 that integrates 16 and 16 in its rigidity
Are arranged with a space closest to each of the plurality of piezoelectric elements 112. The fixing member 101 has a minute structure because the main constituent parts of the head are arranged in high density as described above, but it must fulfill the intended integration function and be easy to manufacture. Therefore, the fixing member 101 has the following restrictions.

1. Since the fixing member 101 integrates the first substrate 110 and the second substrate 116 in rigidity,
The fixing member 101 must be arranged on the supply port 119 where the flow path area is narrow, which is a position where the fixing member 101 can directly contact the second substrate 116, or the vibration plate 130 should have high rigidity.

In order to improve the effect of the above-mentioned integration, the fixing member 101 is also arranged on the nozzle 117 of this embodiment (FIG. 1).

2. Since the fixing member 101 integrates the first substrate 110 and the second substrate 116 in rigidity,
In order to obtain the substantial contact area expansion effect of the second substrate 116,
The rigidity of the vibration plate 130 in which the fixed member 101 and the second substrate 116 are in contact with each other is increased.

3. The fixing member 101 is disposed with a space from the piezoelectric element 112 in order to avoid deformation due to thickness displacement of the piezoelectric element 112.

4. The fixing member 101 is the first substrate 110.
Stuck to.

A manufacturing method of this embodiment for satisfying the above restrictions will be described. Further, the operation of the present invention will be described in detail here.

First, as for the base 115 of the first substrate 110, electrodes, which are prototypes of the signal electrode 141 and the common electrode 142, are mounted on the surface thereof as shown in FIG. Then, the signal electrode 151 and the common electrode 152 of the piezoelectric body 111 are electrically connected and joined to the respective electrodes of the base 115 as shown in FIG. 4B. Then, the piezoelectric element 112 is formed between the grooves 122 by machining the plurality of grooves 122 as shown in FIG. Base 115
The upper signal electrode 141 is simultaneously divided and formed by processing the groove 122. Further, the common electrode 142 is also divided at the same time, but since the side electrode of the base 115 is used for mounting here, no additional component is required. Electrode mounting is easily performed by this manufacturing method.

Then, the fixing member 1 for integrating the first substrate 110 and the second substrate 116 on the first substrate 110.
01 is disposed on the supply port 119 of the second substrate 116 and on the nozzle 117. This makes the base 1 rigid
Since the fixing member 101 installed in the vicinity of each of the piezoelectric elements 112 bridges the rigidity of the piezoelectric element 112 and the second substrate 116, the rigidity of the base 115 is increased. The deformation of the piezoelectric element 112 can be suppressed, the crosstalk transmitted through the second substrate 116 can be drastically reduced, and the thickness displacement of the piezoelectric element 112 can be efficiently transmitted to the pressure chamber 118.

As a method of manufacturing the fixing member 101, there is a method of joining the fixing member 101 to the position of FIG. 4b before the groove 122 of the piezoelectric element 112 is processed, and another similar example is the same position after the groove 122 is processed. There is a method of joining the fixing member 101 to the. In either case, it is necessary to control the thickness of the fixing member 101 in order to facilitate the joining with the diaphragm 130, and the surface to be joined with the second substrate 116 is polished. The piezoelectric elements 112 arranged in high density have low rigidity because they are processed into a shape having a dimension of 0.1 mm or less on one side as described above, and it is difficult to control the thickness after processing the grooves 122. 122 Fixing member 10 before processing
1 is joined.

As another example, the inactive portion 114 of the piezoelectric element 112 is extended as shown in FIG. 4 (b), and the active portion 113 is arranged in the range where it abuts the pressure chamber 118.
Then, the minute inactive portions 114 are left on both ends of the active portion 113, and divided E by the cutting means described above. Here, the piezoelectric element 11
2 surface electrodes are mounted. First, the division E is filled with a conductive adhesive to form a surface electrode of the piezoelectric element 112. Thereafter, as shown in FIG. 4C, the behavior of the inactive portion 114 preventing the displacement of the thickness of the active portion 113 in a state where the surface electrodes 151 and 152 of the piezoelectric element 112 and the electrodes on the base 115 are secured. The fixing member 101 and the piezoelectric element 112 are divided again in order to absorb the thickness displacement of the active portion 113 and to make the behavior of causing the thickness displacement despite the inactive portion 114 independent. After disposing the fixing member 101 as described above, the groove 12
The piezoelectric element 112 is formed by performing two processes.

The size of the fixing member 101 is the second substrate 11
Table 3 shows the influence of the range where 6 can be fixed.

[0042]

[Table 3]

Next, in the vibration plate 130, the portion where the fixing member 101 abuts on the second substrate 116 in the above-described manufacturing method is substantially increased in rigidity when integrated with the first substrate 110. Increase the film thickness. However, the thin film part should be minimized and the others should be thick film parts so that it can be easily handled as a component. Specifically, the contact portion with the pressure chamber 118 is made thin, but the other portions are made thicker. By the way, in order to efficiently transmit the thickness displacement of the piezoelectric element 112 to the pressure chamber 118, a protrusion G is provided at the center of the thin film portion as shown in the figure. As a result, the piezoelectric element 112 and the fixing member 101 can be easily joined, but it is necessary that the piezoelectric element 112 and the fixing member 101 have the same thickness.

Regarding the second substrate 116, the nozzle 117 adjacent to the pressure chamber 118 has a very small width or can be formed as a hole in the side wall of the second substrate 116, which is desirable as the fixing member 101 fixing portion. But,
In the direction perpendicular to the direction in which the plurality of piezoelectric elements 112 of the nozzle 117 are arranged, the width is as small as 0.1 or less, so the bonding area is very small. Further, similarly to the above, the supply port 119 adjacent to the pressure chamber 118 controls the ink ejection pressure dispersion, so that the volume of the supply port becomes small, and it is optimal as the fixing portion of the fixing member 101. Moreover, since the rigidity of the vibrating plate 130 around the pressure chamber 118 is increased as described in the configuration of the vibrating plate 130, the fixing member 101 can be arranged large with respect to the abutting portion of the second substrate 116. Substrate 110 and second substrate 11
It is possible to dramatically increase the effect of integration with the rigidity of No. 6.

By the way, the reservoir 120 adjacent to the supply port 119 has a sufficiently large volume because it is necessary to sufficiently supply the ink to each pressure chamber 118 and the same supply in the plurality of pressure chambers 118. Has become.
The width of the piezoelectric elements 112 in the direction perpendicular to the plurality of arrangement directions is
Has a little over 2 mm. Therefore, for the arrangement of the fixing member 101 to the supply port 119, the first part using the periphery of the reservoir is used.
Integrating the substrate 110 and the second substrate 116 makes it difficult to obtain the intended effect.

[0046]

As described above, the first substrate and the second substrate
By integrating the substrate and the substrate with a fixing member that is arranged near the piezoelectric element, crosstalk between adjacent nozzles can be eliminated, and the force generated by the piezoelectric element can be efficiently transmitted to ink droplet ejection. Become. Therefore, it is possible to realize a small ink jet print head having a high printing quality with stable ink ejection characteristics by a plurality of nozzles arranged in high density.

[Brief description of drawings]

FIG. 1 is an exploded perspective view for explaining a configuration of an inkjet print head of the present invention.

FIG. 2 is a partial cross-sectional view for explaining the configuration of the inkjet print head of the present invention.

FIG. 3 is a partial cross-sectional view for explaining an ink discharge method and an ink supply method.

FIG. 4 is a view for explaining the manufacturing method of the present invention.

FIG. 5 is a partially exploded perspective view for explaining a conventional configuration.

FIG. 6 is a partially exploded perspective view for explaining another conventional configuration.

FIG. 7 is a partial cross-sectional view for explaining another conventional configuration.

FIG. 8 is a partial cross-sectional view illustrating a problem of a conventional inkjet printhead.

FIG. 9 is a partial cross-sectional view for explaining another embodiment of the inkjet print head of the present invention.

[Explanation of symbols]

 101 Fixing member 110 First substrate 111 Piezoelectric body 112 Piezoelectric element 113 Active part 114 Inactive part 115 Base 116 Second substrate 117 Nozzle 118 Pressure chamber 119 Supply port 120 Reservoir 125 Partition wall 141 Signal electrode (base) 142 Common Electrode (base) 151 Signal electrode (piezoelectric element) 152 Common electrode (piezoelectric element)

Claims (4)

[Claims] 1. A second parallel arrangement of a plurality of pressure chambers each having a reservoir and a supply port communicating with the reservoir on the same plane, a nozzle on one wall surface, and a vibrating plate on another wall surface of the wall.
An ink-jet print head comprising: a substrate and a first substrate that has a one-to-one correspondence with the pressure chambers and a piezoelectric element whose displacement surface is connected to the vibration plate is arrayed and fixed; and a plurality of the piezoelectric elements are arrayed. An ink jet device characterized in that a gap between the first substrate and the second substrate is filled near the piezoelectric element in the vertical direction, and a member is arranged with a gap from the piezoelectric element. Print head. 2. The ink jet printing according to claim 1, wherein the member is fixed on the second substrate to the supply port portion adjacent to the pressure chamber via the vibrating plate. head. 3. An active portion of the piezoelectric element, the thickness of which is displaced,
The ink jet print head according to claim 1, wherein the piezoelectric element is arranged within a range of the pressure chamber width in a vertical direction in which a plurality of the piezoelectric elements are arranged. 4. The vibrating plate for transmitting the thickness displacement of the piezoelectric element to the pressure chamber has low rigidity in a portion in contact with ink in the pressure chamber and high rigidity in the vicinity of the portion. The ink jet type print head according to claim 1.