JPH07290702A - Ink jet recording apparatus - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by eliminating energy loss by transmitting the energy generated by a piezoelectric element to a pressure chamber by the deformation of an elastomer to emit ink. CONSTITUTION:An orifice plate 1 and an ink passage plate 2 and a piezoelectric unit 4 and a vibration plate 3 are bonded by an epoxy adhesive high in Young's modulus and rigidity while the ink passage plate 2 and the vibration plate 3 are bonded by the elastomer 50 low in Young's modulus arranged on the vibration plate 3. A piezoelectric element 4 is extended in the direction shown by an arrow by applying voltage to electrodes 8, 9 and the vibration plate 3 bonded to the piezoelectric element 4 is displaced at the same time and the elastomer 50 receives compression force to be deformed. By this mechanism, energy is transmitted to a pressure chamber 5 and ink is emitted from an orifice 7 and the printing corresponding to recording data is performed. Since the energy generated by the piezoelectric element 7 is transmitted to the pressure chamber 5 by the deformation of the elastomer 50, energy loss is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet type recording apparatus, and more particularly to a recording head of a type that forms an ink droplet by driving a vibrator and performs recording, and a recording apparatus equipped with the same.

[0002]

2. Description of the Related Art FIG. 10 is an external perspective view of a head portion of a conventional ink jet recording apparatus, FIG. 11 is an exploded perspective view of the same, and FIG. 12 (A) shows a vibration state of a conventional ink jet recording apparatus (no voltage applied). 12 is a diagram showing the driving state (when a voltage is applied), and FIG.
3 shows a dimensional relationship diagram.

Reference numeral 100 denotes the entire nozzle unit, and the nozzle unit 100 has an orifice (ink ejection portion) 107.
The ink flow path plate 102, the vibrating plate 103, and the piezoelectric element unit 104 are stacked in this order from the top, with the orifice plate 101 provided with the above as the uppermost part. The piezoelectric element unit 104 has electrodes 108 and 109 on the upper and lower portions, respectively. Further, the partition wall 106 and the vibrating plate 103 in the ink flow path plate 102 are fixed by an adhesive agent 112, and the piezoelectric element unit 104 and the partition wall 106 are fixed by an adhesive agent 111. Specifically, the pressure chamber 10 is formed by adhering the orifice plate 101 made of glass, the ink flow path plate 102, and the vibration plate 103 made of stainless steel.
Make up 5. Next, the piezoelectric element unit 104 made of lead zirconate titanate is bonded to positions corresponding to the ink pressure chamber 105 and the partition wall 106 to form the nozzle unit 100, as shown in FIG.

Electrodes 108 and 10 of the piezoelectric element unit
By applying a voltage across the piezoelectric element 9, the piezoelectric element expands in the direction of the arrow as shown in FIG.
Bends, the volume of the pressure chamber decreases, and ink is ejected from the orifice 107 by this energy, so that printing according to the recorded information is performed. An on-demand type ink jet head that ejects ink from an orifice by changing a piezoelectric element according to the applied voltage is disclosed in Japanese Patent Laid-Open No. Hei 3 (1999) -311.
No. 10845.

[0005]

In the conventional system, the first method is used.
In addition, due to the principle that the diaphragm formed of metal or glass having a high Young's modulus is bent by the displacement of the piezoelectric element, the energy loss at this portion is large, and high energy is required for ink ejection. Further, in order to suppress the loss in this portion and efficiently transmit the displacement of the piezoelectric element to the pressure chamber, it was necessary to make the diaphragm as thin as possible (a ₆ dimension: about 50 μm or less). However, this tends to cause damage or deformation during handling in the production process, making it difficult to handle and reducing the yield of the manufacturing process. Further, in order to efficiently transmit the displacement of the piezoelectric element and to stabilize the characteristic when the diaphragm 103 is flexible, it is necessary to bond the piezoelectric element to the center of the displacement part of the diaphragm with high accuracy (a in FIG. 13). ₁ = a ₂ ). Further, since the displacement of the vibration plate directly affects the characteristics at the time of ink ejection, the vibration plate 103
It is necessary to control the thickness (a ₆ dimension) of the product with high precision, and a precise processing step such as lapping is required, resulting in high cost.
Further, in order to stabilize the displacement of the diaphragm 103, the protrusion of the adhesive 11 between the piezoelectric element and the diaphragm to the flexible portion of the diaphragm restrains the movement of the diaphragm and affects the displacement. It was necessary to apply the adhesive accurately and evenly, and it was necessary to use a screen printing transfer method or the like.
Due to this, there is a limit and management is difficult.

Secondly, according to the conventional method, the flexible portion a ₁ , which has a structure in which the diaphragm 103 is directly bent by the displacement of the piezoelectric element,
Since the dimension a ₂ is required, the width of the piezoelectric element needs to be smaller than the pressure chamber width 105 (a ₄ > a ₃ ). It is possible to take out a large generated force by increasing the width of the piezoelectric element 104, but this is disadvantageous to the design for low voltage driving because of the above-mentioned restriction. Further, the width a ₃ of the piezoelectric element has a limit in terms of mechanical processing accuracy and strength of a dicing saw, a wire saw, etc. when manufacturing the piezoelectric element unit 104, and it is determined by this processing accuracy, and therefore is about 1.
The nozzle pitch a ₅ is about 2 μm.
The limit is 50 μm, and it is difficult to increase the nozzle density.

In the conventional method, thirdly, an epoxy adhesive having a high Young's modulus is used in order to suppress the cross-talk between the diaphragm 103 and the pressure chamber partition wall 106 as much as possible through the diaphragm 103. Although it is necessary to firmly bond them, however, the protrusion of the adhesive 12 having a high Young's modulus to the flexible portion of the vibration plate restrains the movement of the vibration plate 103 and greatly affects the displacement at the time of flexion. Since it was necessary to uniformly and highly accurately form the adhesive layer on this portion, it was carried out by screen printing, a transfer method, a dispenser or the like, but it is limited and difficult to manage.
In addition, since it is a diaphragm structure on one flat plate connected by the diaphragm portion between each channel, when an adjacent channel of this channel is driven, it is affected by this channel via the connecting portion of the diaphragm, This crosstalk has a problem in that the ink flying state is affected and, as a result, the print quality is degraded.

[0008]

According to another aspect of the present invention, there is provided an ink jet recording apparatus for ejecting ink to form an image on a recording medium, the partition wall constituting a pressure chamber connected to an ink ejecting section. The inkjet recording device is characterized in that an elastic body is arranged between the pressure chamber and a vibration plate for transmitting the pressure applied by the piezoelectric element to the pressure chamber.

The ink jet recording apparatus according to claim 2 is characterized in that, in a cross section perpendicular to the ink ejection direction, the width of the piezoelectric element is equal to or larger than the width of the pressure chambers facing each other. Is.

An ink jet recording apparatus according to a third aspect of the present invention is the ink jet recording apparatus according to the first aspect, wherein the elastic body is arranged on the entire surface of the diaphragm.

[0011]

According to the ink jet recording apparatus of the present invention, by disposing the elastic body between the partition wall forming the pressure chamber and the vibrating plate, this portion is deformed as the piezoelectric element expands and contracts, and the pressure chamber volume changes. Ink is ejected from the orifice and printing is performed according to the recording information. Therefore, unlike the conventional type, it is not necessary to bend the diaphragm having a high Young's modulus, and the elastic body having a low Young's modulus is deformed, so that it is possible to drive with low energy and low energy. Also, since it is no longer necessary to bend the diaphragm, it is possible to make the thickness more than the strength required for handling during production (thickness 0.1 mm), so that the center portion of the diaphragm does not have to be accurate, Since it is not necessary to bond the piezoelectric element and the displacement of the diaphragm is not affected even by a slight displacement, the volume change amount of the pressure chamber does not change and the characteristics at the time of ink flight are stable and high-quality printing is possible. Also, since the displacement of the diaphragm is not affected by the thickness of the diaphragm, the characteristics will not change, so it is possible to eliminate the steps such as grinding and lapping to control the thickness accurately. Cost reduction is possible.
Further, even if the adhesive for bonding the piezoelectric element sticks out to the vibrating plate, it is not necessary to bend the vibrating plate in that part, so there is no effect on the characteristics, and it is not necessary to accurately suppress the application unevenness of the adhesive. Therefore, the application management can be simplified.

According to the ink jet recording apparatus of the second aspect, since the elastic body is deformed by the displacement of the piezoelectric element, the width of the piezoelectric element can be made larger than the width of the pressure chamber. As a result, it is possible to increase the piezoelectric element width b ₂ (about 200 μm) compared to the conventional type (for example, the conventional piezoelectric element width (about 100 μm) for the conventional nozzle pitch (about 250 μm)). Becomes possible,
Since it is possible to obtain the generated energy for that increase,
It is possible to reduce the voltage by about half that of the conventional type. Also, the piezoelectric element width b ₂ is limited to 100 μm in terms of the machining accuracy and strength of the dicing saw and wire saw when manufacturing the piezoelectric element unit, but this configuration allows the nozzle pitch to be about 125 μm. As a result, high-density mounting that is about twice that of the conventional one is possible.

According to the ink jet recording apparatus of the third aspect, it is not necessary to bend the diaphragm due to the displacement of the piezoelectric element as in the conventional type, and the elastic adhesive is used instead of the high rigidity adhesive. Since it is now possible, it is not necessary to apply the adhesive to only the parts that require high precision using screen printing, etc. in consideration of the influence of the adhesive on the displacement of the diaphragm as in the past. It is possible to place it on the entire surface. As described above, since the patterning of the adhesive is unnecessary, the production can be facilitated. Further, even with the conventional coating method, the control of the coating accuracy can be simplified and the production can be facilitated.

[0014]

【Example】

(Embodiment 1) A first embodiment of an ink jet recording apparatus according to the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of an ink jet recording head as one embodiment of the present invention. FIG. 2 is an exploded perspective view of the ink jet recording head shown in FIG. As shown in the figure, a plurality of orifices 7 are formed in the orifice plate 1 at predetermined intervals. The orifice plate 1 is made of photosensitive glass or silicone and is formed by etching or the like. The ink flow path plate 22 is made of photosensitive glass and is formed by etching. The vibration plate 3 is made of stainless steel or photosensitive glass and is formed by being processed by etching or the like. The elastic body 50 is made of silicone, urethane resin or the like having a low Young's modulus, and is formed on the vibration plate by spin coating, screen printing, a dispenser or the like. The piezoelectric element unit 4 is made of lead zirconate titanate and has grooves formed by machining such as a dicing saw and a wire saw to form driving portions corresponding to the respective channels.

The orifice plate 1 and the ink flow path plate 2 are bonded to each other, and the piezoelectric element unit 4 and the vibration plate 3 are bonded to each other with a highly rigid epoxy adhesive having a high Young's modulus, and the ink flow path plate 2 and the vibration plate 3 are bonded to each other. It is adhered by a rubber elastic body 50 having a low Young's modulus arranged on the diaphragm.

3 (A) and 3 (B) are cross-sectional views showing a driving state. FIG. 3 (A) shows a state in which no voltage is applied, and FIG. 3 (B) shows a state in which voltage is applied. Electrodes 8 and 9 arranged above and below the piezoelectric element
By applying a voltage between them, the piezoelectric element expands in the arrow direction by the piezoelectric vertical effect. As a result, the vibrating plate joined to the piezoelectric element is simultaneously displaced, so that the elastic body is subjected to compressive stress and deformed (FIG. 3 (B)). By these, energy is transmitted to the pressure chamber, ink is ejected from the orifice 7, and printing according to the recording information is performed.

8A and 8B are layout views of an elastic body of the ink jet recording apparatus of the present invention. FIG. 8A shows only necessary portions, FIG. 8B shows the entire surface of the diaphragm, and FIG. 8C shows a shield shape. The one arranged on one side is shown. Although the conventional method (A) is used, the present invention enables the arrangement of the elastic body (adhesive having elasticity) of (B) or (C).

Although a single-layer piezoelectric element has been described in this drawing, it is possible to easily use a piezoelectric element laminated in a direction parallel to the diaphragm.

(Embodiment 2) A second embodiment of the ink jet recording apparatus according to the present invention will be described with reference to FIGS.

FIG. 5 is a perspective view of an ink jet recording head as a second embodiment of the present invention. FIG. 6 is an exploded perspective view of the ink jet recording head shown in FIG. As shown in the figure, a plurality of orifices 27 are formed in the orifice plate 31 at predetermined intervals. The orifice plate 31 is made of photosensitive glass or silicone and is formed by being processed by etching or the like. The ink flow path plate 35 is made of photosensitive glass and is formed by etching. The diaphragm 23 is made of stainless steel or photosensitive glass and is formed by being processed by etching or the like. The elastic body 34 is made of silicone, urethane resin or the like having a low Young's modulus and is formed by using spin coating, screen printing, a dispenser or the like on the vibration plate. The base block 32 is a piezoelectric element block 2 formed by molding a resin or metal material.
Reference numeral 4 is made of lead zirconate titanate, and is bonded to a fixing base 33 made of ceramics or glass, and then processed into a comb tooth shape by mechanical processing such as a dicing saw or a wire saw to form a driving portion corresponding to each channel. .
Between the orifice plate 31 and the ink flow path plate 35,
Between the diaphragm 23 and the base block 32, the base block 3
2 and the fixed base 33, the piezoelectric element block 24 and the diaphragm 23
The spaces are bonded with a highly rigid epoxy adhesive having a high Young's modulus. The ink flow path plate 35 and the vibration plate 23 are bonded by a rubber elastic body 34 having a low Young's modulus arranged on the vibration plate.

FIGS. 7A, 7B and 7C are a sectional view and a side view showing a driving state, wherein FIG. 7A is a state in which no voltage is applied, FIG. 7B is a state in which voltage is applied, and FIG. Represents a side view of (B). By applying a voltage between the electrodes 28 and 29 arranged above and below the piezoelectric element, the piezoelectric element contracts in the arrow direction by the piezoelectric lateral effect. As a result, the vibrating plate bonded to the piezoelectric element is also displaced at the same time, so that the elastic body receives tensile stress and is deformed (FIGS. 7B and 7C). In this state, the pressure chamber 25
The volume increases and ink is introduced from the ink supply port 30. Next, by interrupting the voltage application, the state returns to the state when no voltage is applied (FIG. 7A), and the ink is ejected from the orifice hole 27 in accordance with the change in the volume of the pressure chamber at this time, according to the recording information. Printing is performed. Although a single-layer piezoelectric element has been described in this drawing, it is possible to easily use a piezoelectric element stacked vertically to the diaphragm.

(Embodiment 3) A third embodiment of the ink jet recording apparatus of the present invention will be described with reference to FIG.

In this embodiment, by separating the channels of the diaphragm from each other, the influence (crosstalk) on the main channel via the diaphragm when the adjacent channels are driven is eliminated, so that the state during ink flight is stabilized. , Which enables high-quality recording. That is, as shown in FIGS. 9A and 9B, the diaphragm is completely separated for each orifice (ink ejection port), but as shown in FIGS. Only separate or see Figure 9 (E) (F)
As described above, both ends may be continuous and only the central part may be separated. In addition, (C) (D), (E)
In the case of (F), it is not necessary to bond a diaphragm for each channel. Further, according to the present invention, since the vibrating plate is separated between each channel, the influence (crosstalk) on the main channel due to the driving of the adjacent channel is eliminated, so that the particle formation during ink flight is stable and high-quality printing is performed. It will be possible. Further, the structure in which one end or both ends of the diaphragm is common allows the manufacturing process to be carried out in the same manner as in the past without the need to attach the diaphragm to each channel.

The difference in the influence of the piezoelectric element between the present invention and the conventional example on the pressure chamber (the difference in the changing state of the piezoelectric element) will be described in detail below with reference to FIGS. 3, 7, 12, and 14. Explained.

As shown in FIG. 12, the conventional method is a method in which the central portion of the fixed beam all around is subjected to a uniformly distributed load by a piezoelectric element, and the beam shape is considered as a column shape (FIG. 14A). , The maximum amount of deflection δ _{MAX at} the center is expressed by the following equation.

Δ _MAX = 3 (m−1) (7m + 3) PR ² / 16πE ₁ m ² t ₁ ³ δ _MAX : Maximum deflection amount t ₁ : Plate thickness P: Total load
R: radius E ₁ : Young's modulus of beam 1 / m: Poisson's ratio Next, in the present invention, as shown in FIGS. 3 and 7, compression or tensile stress is applied to an elastic body by a piezoelectric element to generate strain. In the case of considering the entire circumference of the cylindrical beam as a shape supported by an elastic body (see FIG. 14).
(B)), this distortion amount δ is expressed by the following equation.

Δ = Pt ₂ / SE ₂ δ: Strain amount S: Area of elastic body subjected to load P: Total load E ₂ : Young's modulus of elastic body The difference in transmission efficiency is that the total load generated by the piezoelectric element is constant. _Therefore, it is represented by δ / δ _MAX , and when a typical numerical value is substituted for each, E ₁ = 2 × 10 ⁴ (kgf / mm ² ) t ₁ = 0.1 mm
R = 0.1 mm E ₂ = 1 (kgf / mm ² ) t ₂ = 0.001 mm S
= 12.5 ⁻³ πmm ² 1 / m = 0.3, δ / δ _MAX = 1500, and the present invention can achieve a high efficiency of about 1500 times that of the conventional method.

[0029]

According to the ink jet recording apparatus of the first aspect, the elastic body is arranged between the pressure chamber wall and the vibrating plate, and the energy generated by the piezoelectric element is transmitted to the pressure chamber by the deformation of the elastic body. Because it is configured to eject ink,
Unlike the conventional type, it is possible to obtain a head with good energy transmission efficiency without energy loss caused by bending the diaphragm, and low voltage driving is possible. In addition, since it is not necessary to bend the diaphragm, it is possible to make the thickness sufficient, so that the required strength at the time of production can be obtained, defects due to breakage deformation etc. can be eliminated and yield can be improved. This simplifies production and reduces costs. Further, since the flexible portion of the diaphragm is eliminated by this configuration, it is not always necessary to position and adhere the piezoelectric element to the central portion of the diaphragm with high accuracy, and this management can be simplified. Further, unlike the conventional type, the bonding position of the piezoelectric element does not affect the characteristics when ink is ejected, so that high-quality printing is possible.

Further, since the thickness of the vibration plate does not affect the efficiency at the time of energy transmission, the precision control of the thickness is simplified, so that the processing such as lapping is not necessary and the cost can be reduced. . Further, it is not necessary to control the protrusion of the adhesive between the piezoelectric element and the vibration plate, and the application method and the application amount can be simplified and the manufacturing can be facilitated.

According to the ink jet recording apparatus of the second aspect, since the width of the piezoelectric element can be made larger than the width of the pressure chamber, the generated energy can be increased as compared with the conventional type, so that the low voltage is applied. Driving is possible and it is about 1
It can be driven with a voltage of / 2. Further, according to the present invention, by making the width of the piezoelectric element equal to or larger than the width of the pressure chamber, it is possible to highly integrate the nozzles, and it is possible to realize high-density mounting which is about twice that of the conventional case.

According to the third aspect of the present invention, an adhesive having a high Young's modulus is conventionally used, whereas an elastic body having a low Young's modulus is arranged so as to also function as an adhesive. Also, since the protrusion of the elastic adhesive does not affect the displacement of the diaphragm, and thus the characteristics of ink flight due to this,
The application amount can be controlled and the application method can be simplified. Further, in the configuration of the present invention, since the elastic body is used, even if it is applied to the entire surface of the vibration plate, the ink flying characteristics are not affected, and by performing the entire surface application, the high precision application step is not required. The production can be facilitated. Further, the production is further facilitated by using a sheet-like elastic adhesive sheet instead of applying the elastic body to the diaphragm.

[Brief description of drawings]

FIG. 1 is an external perspective view of a head portion of an inkjet recording apparatus of the present invention.

FIG. 2 is an exploded perspective view of a head portion of the inkjet recording apparatus of the present invention.

FIG. 3A is a diagram showing a driving state (when no voltage is applied) of the inkjet recording apparatus of the present invention. FIG. 6B is a diagram showing a driving state (when a voltage is applied) of the inkjet recording apparatus of the present invention.

FIG. 4 is a dimensional relationship diagram of the inkjet recording apparatus of the present invention.

FIG. 5 is an external perspective view of a head portion representing another embodiment of the present invention.

FIG. 6 is an exploded perspective view of a head portion showing another embodiment of the present invention.

FIG. 7A is a diagram showing a driving state (when no voltage is applied) in another example of the present invention. FIG. 6B is a diagram showing a driving state (when a voltage is applied) in another example of the present invention. (C) It is a side view in (B).

FIG. 8 (A) is an elastic body layout diagram of the inkjet recording apparatus of the present invention (arrangement only at necessary portions). (B) Is an elastic body layout diagram of the inkjet recording apparatus of the present invention (diaphragm entire surface arrangement). (C) is an elastic body layout of the inkjet recording apparatus of the present invention (shield elastic body).

FIG. 9A is a diagram showing the shape of a vibration plate of an inkjet recording apparatus according to the present invention (channel-individual type). (B) It is a side view in (A). (C) It is a diaphragm shape diagram of the ink jet recording apparatus in the present invention (one end common type). It is a side view in (D) and (C). (E) It is a diaphragm shape diagram of the inkjet recording apparatus in the present invention (common type at both ends). It is a side view in (F) and (E).

FIG. 10 is an external perspective view of a conventional inkjet recording apparatus.

FIG. 11 is an exploded perspective view of a conventional inkjet recording apparatus.

FIG. 12A is a diagram showing a driving state (when no voltage is applied) of the conventional inkjet recording apparatus. (B) is a diagram showing a driving state (when a voltage is applied) of the inkjet recording apparatus of the conventional example.

FIG. 13 is a dimensional relationship diagram of a conventional inkjet recording apparatus.

FIG. 14A is a diagram of the vicinity of a piezoelectric element of an inkjet recording device of a conventional example. FIG. 3B is a diagram of the vicinity of the piezoelectric element of the inkjet recording apparatus of the present invention.

[Explanation of symbols]

1 Orifice Plate 2 Ink Flow Plate 3 Vibrating Plate 4 Piezoelectric Element Unit 5 Pressure Chamber 6 Partition 7 Orifice (Ink Discharging Section) 8 Electrode 9 Electrode 10 Nozzle Unit (Head) 23 Vibrating Plate 24 Piezoelectric Element Block 25 Pressure Chamber 26 Partition 27 Orifice 28 Electrode 29 Electrode 30 Ink Supply Port 31 Orifice Plate 32 Base Block 33 Fixing Base 34 Elastic Body 35 Ink Flow Path Plate 50 Elastic Body 100 Nozzle Unit 101 Orifice Plate 102 Ink Flow Path Plate 103 Vibrating Plate 104 Piezoelectric Element Unit 105 Pressure Chamber 106 Partition 107 Orifice (ink ejection part) 108 Electrode 109 Electrode 111 Adhesive 112 Adhesive a ₁ Vibration plate flexible part size a ₂ Vibration plate flexible part size a ₃ Piezoelectric element width a ₄ Pressure chamber width a ₅ Nozzle pitch ₆ diaphragm thickness b ₁ pressure chamber width b ₂ piezoelectric element width b ₃ nozzle pitches

Claims (3)

[Claims] 1. A partition between a partition forming a pressure chamber that is connected to an ink jet ejecting unit that ejects ink to form an image on a recording medium, and a diaphragm that transmits the pressure applied by a piezoelectric element to the pressure chamber. An ink jet recording apparatus having an elastic body. 2. In a cross section perpendicular to the ink ejection direction,
2. The ink jet recording apparatus according to claim 1, wherein the width of the piezoelectric element is equal to or larger than the width of the pressure chambers facing each other. 3. The ink jet recording apparatus according to claim 1, wherein the elastic body is arranged on the entire surface of the diaphragm.