JP2758633B2 - Ink jet recording device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an ink jet recording apparatus, and more particularly, to a head mechanism of the ink jet recording apparatus.

2. Description of the Related Art Conventional techniques according to the present invention include Japanese Patent Publication No. 60-8953, Japanese Patent Application Laid-Open No. 63-252750, Japanese Patent Application No. 61-45542, and Japanese Patent Application Laid-Open No. 59-159358.

A conventional on-demand type ink jet head using a piezoelectric actuator has a drawback that it is difficult to achieve high integration of the actuator, and if the integration is increased, the driving voltage increases. It is the above-mentioned prior art that improved them.

Japanese Patent Publication No. 60-8953 discloses a method in which a piezoelectric actuator is provided in ink opposite to a nozzle, and the piezoelectric actuator is driven to perform ink ejection. It only contributes, and there is a limit to high integration due to the characteristics of the piezoelectric vibrator.

Japanese Patent Publication No. 61-45542 discloses a beam-shaped piezoelectric actuator for the partition wall of the flow path, and solves the problem of a reduction in the actuator area due to high integration by using a beam-shaped actuator for the flow path partition wall. However, there are difficulties in processing such as processing and disposing the piezoelectric element, and reduction in processing cost is required.

Japanese Patent Application Laid-Open No. 63-252750 discloses a method in which a partition of a flow path is driven by a piezoelectric actuator to eject ink. Solves the problem of reduction in actuator area due to high integration, and furthermore,
and better efficiency by driving at d ₁₅ mode. However, manufacturing difficulties such as processing of piezoelectric elements and formation of electrodes cannot be solved, and reduction of processing cost is required. In addition, since voltage is applied to the drive electrode and the ground electrode in a complicated manner, connection and extraction of the electrodes are complicated.

Japanese Patent Application Laid-Open No. 59-159358 discloses a structure in which a wall portion of a flow path is formed of a piezoelectric actuator (block shape), and a wall portion of a flow path is formed of a block-shaped piezoelectric actuator. However, the degree of integration is reduced due to the presence of a buffer for preventing mutual interference.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and enables a highly integrated head to be easily manufactured using a piezoelectric vibrator having low power consumption, improving the efficiency of the head characteristics, and simplifying the driving. An object of the present invention is to provide a head of an ink jet recording apparatus that can be executed by a method.

Configuration In order to achieve the above object, the present invention includes an ink flow path communicating with a discharge port, a flow path partition for individually dividing the ink flow path, and an ink supply unit communicating with the ink flow path. Then, a piezoelectric vibrator for causing deformation at the joint portion of the flow path partition is provided, and by driving the piezoelectric vibrator, a deformation is generated at a root portion of the flow path partition, and the flow path partition is formed. In an inkjet head that causes displacement and generates a pressure change in the ink flow path to discharge ink droplets from the discharge port, selectively driving one portion of the piezoelectric vibrator corresponding to the ink flow path. According to the above, causing displacement on both side walls of the flow path forming the corresponding ink flow path, further, the piezoelectric vibrator corresponding to the ink flow path is substantially cut for each ink flow path, And even The piezoelectric vibrator is driven in the thickness vibration direction, and further, the flow path partition is formed of Si, and a bonding surface between the flow path partition and the piezoelectric vibrator is formed of Si.
The present invention is characterized in that a bottom wall portion having a smaller etching rate is provided. Hereinafter, a description will be given based on examples of the present invention.

FIG. 1 is a configuration diagram for explaining an embodiment of an ink jet recording apparatus according to the present invention. In FIG. Is a flow path partition, 6 is an upper substrate, 9 is a slit, 11 is a bottom wall, 12
Is a discharge port. The piezoelectric vibrator 2 is bonded on the substrate 3 and is provided with a slit 9 so as to substantially separate a flat plate. A channel partition is disposed on the piezoelectric vibrator 2, and a bottom wall 11 is joined to the piezoelectric vibrator 2. Above the bottom wall 11, the flow path partition 5 has a slit 9
Are arranged to correspond to. The upper substrate 6 is joined to the upper surface of the flow path partition 5, whereby each ink flow path 4 is formed separately. A discharge port plate 1 having a discharge port 12 corresponding to the ink flow path 4 is joined to one end of the ink flow path 4. The other end of the ink flow path 4 is connected to a common liquid chamber, and further connected to an ink supply section (not shown) communicating with the liquid reservoir.

FIGS. 2A and 2B are views for explaining the operation of the head unit of the present invention, and are AA sectional views of FIG. When the voltage applied to the drive electrodes 7-4 (FIG. 2 -a shows the state before applying a voltage) piezoelectric vibrator 2-4 cause extension in the thickness direction (d ₃₃ direction strain) distorted (piezoelectric Vibrator 2-
4 is polarized in the thickness direction). As a result, the flow path partition walls 5-3 and 5-4 are flexed and deformed as a whole because the joints thereof are displaced (FIG. 2B).

As a result, the ink flow path 4-4 increases in volume. By stopping the voltage application to the piezoelectric vibrator 2-4 in this state, the strain energy acts in a direction to return to the original state, so that the volume in the ink flow path 4-4 rapidly decreases, and the ink increases due to the increase in pressure. From the discharge port 12 corresponding to the flow path 4-4,
Ink droplets are ejected. At this time, the rise of the voltage application is performed for a relatively long time, and the rise is performed for a short time.

Conversely, voltage application causes the piezoelectric vibrator 2-4 to shrink in the thickness direction, thereby causing the flow path partition walls 5-3 and 5-4 to bend inward relative to the ink flow path 4-4. By deforming, it is also possible to eject ink droplets by a pressure change when the voltage application is ON. At this time, the rise of the voltage application is performed in a relatively short time, and the rise is performed in a long time.

The expansion and contraction of the piezoelectric vibrator 2 may be set by appropriately selecting the polarization direction and the electric field direction. In the drawing, reference numeral 8 denotes a common electrode.

Next, a method of processing the head will be described with reference to FIG. The piezoelectric vibrator 2 (thickness: 0.1 to 0.5 mm) is bonded to the substrate 3 by bonding or the like.

The grooves are formed on the piezoelectric vibrator 2 by appropriately using machining such as cutting, various kinds of etching, beam machining such as laser, electric discharge machining, ultrasonic machining, etc., alone or in combination. Form. Here, it is sufficient that the slit 9 substantially separates the piezoelectric vibrator 2. The piezoelectric vibrator 2 does not need to be completely separated as shown in FIG. 4 to be described later, and a slit 9 may be provided up to the substrate 3 as shown in FIG.

At this time, since the piezoelectric vibrator 2 has electrodes applied in advance on both surfaces in the thickness direction, the upper surface becomes a drive electrode separately and independently by the groove processing, and the lower surface becomes a common electrode. In the case of FIG. 5, a common electrode can be achieved by making the substrate 3 a conductor such as metal or Si (FIG. 3-a).

Next, a member for forming the flow path partition is joined to the piezoelectric vibrator 2.

The flow path partition 5 can be formed in the same manner as the groove processing of the piezoelectric vibrator 2, but can be easily processed by using, for example, a Si anisotropic etching technique. In this case, the bottom wall portion 11 having a smaller etching rate than Si, such as an oxide film layer, a nitride film layer, and a metal film layer, is usually 0.05 μm to 50 μm, and preferably Si.
It is formed with a thickness of 0.05 μm to 10 μm, and most preferably, 0.1 μm to 5 μm. Thereby, the groove processing is performed while leaving the bottom wall portion 11 due to the difference in the etching rate, and the flow path partition wall 5 is formed.
And an ink flow path 4 are formed. At this time, the bottom wall portion 11 functions as a protective layer of the piezoelectric vibrator 2 (when the bottom wall portion 11 is a conductor, an insulating layer is required for a driving electrode of the piezoelectric vibrator 2). On the other hand, since the bottom wall 11 prevents the displacement of the piezoelectric vibrator 2 from being transmitted efficiently, the above-mentioned thickness is desired (FIGS. 3B and 3C). In the drawing, reference numeral 10 denotes a partition member, and 13 denotes a bottom wall layer portion.

In addition, the flow path partition walls 5 and the ink flow paths 4 can be formed by resin molding or a dry film. However, the above-described anisotropic etching of Si is very preferable because the bottom wall 11 can be easily processed in the order of μm.

Next, when the upper substrate 6 is joined to the flow path partition 5, the flow path partition 5
Are formed in a beam shape fixed at both ends, and the ink flow path 4 is also completely separated. At this time, the flow path partition 5 may not be joined to the upper substrate 6 and may have a free end, and the upper substrate 6 may be disposed so that the flow path partition 5 has a cantilever shape. In this case, the gap between the flow path partition 5 and the upper substrate 6 has a sufficient fluid resistance,
Usually, it is desirable to provide a gap of 1 μm to 50 μm, preferably 1 μm to 30 μm, and the ink flow paths 4 are substantially separated independently. The upper substrate 6 is provided on the flow path partition 5.
It is also possible to provide an elastic layer of a suitable rubber, resin or the like at the time of bonding. This elastic layer acts in a direction to weaken the binding force due to the joining of the flow path partition wall 5 to the upper substrate 6, and makes the partition wall intermediate between the above-mentioned fixed-end beam shape and cantilever beam shape. Are completely separated. At this time, the adhesive layer may also serve as the elastic layer.

4 to 7 show another embodiment of the head section of the present invention. Although the method of joining the upper substrate 6 after the processing of the flow path partition is described above, a method of integrally processing the upper substrate 6 and the flow path partition is also used. At this time, for example, the flow path partition 5 may be directly joined to the piezoelectric vibrator 2 (FIG. 4). In this case, a protective layer, an insulating layer, and the like on the electrode surface of the piezoelectric vibrator 2 are required.

FIG. 5 shows a case where the slit 9 is formed up to the portion of the substrate 3.

The groove processing of the piezoelectric vibrator 2 may be performed from the substrate 3 side as shown in FIG. 6 with respect to FIG.

As described above, it is desirable that the piezoelectric vibrator is substantially cut for each ink flow path. However, in order to further simplify processing, the drive electrodes are independently patterned for each ink flow path. It is also possible to form the piezoelectric vibrator without processing the groove (FIG. 7). However, in this case, the characteristics deteriorate.

Further, the piezoelectric vibrator 2 may be of a laminated type, whereby low voltage driving can be achieved.

In the above embodiment, the piezoelectric vibrator is arranged only on one side of the flow path partition wall.
Can be easily bent.

The piezoelectric vibrator 2 and the flow path partition 5 are displaced to cause a pressure change in the ink flow path 4.
A similar displacement also occurs on the joint surface with the nozzles, which is disadvantageous because harmful stress is generated on the discharge port plate 1, the flow path partition wall 5 or the joint surface. Therefore, in order to alleviate or absorb the stress, a method of providing an appropriate adhesive layer at the joint or providing a buffer member can be adopted.

In addition, the arrangement of the discharge port plate 1 is not limited,
The upper surface of the upper substrate 6 may be used.

The embodiments described above can be installed in various combinations.

Effects As is apparent from the above description, according to the present invention, the connection of the drive electrode and the common electrode (earth electrode) is simplified, the processing is facilitated, and the voltage application during driving is simplified. In addition, since the individual piezoelectric vibrators are substantially separated, vibration interference between the piezoelectric vibrators is eliminated, the displacement can be efficiently applied to the flow path partition wall, and the driving voltage can be reduced. , Reduced mutual interference.

In addition, since the drive electrode is formed by processing the groove of the piezoelectric element, a special electrode forming step is not required. Further, the discharge efficiency is improved, and the processing for forming the flow path partition wall portion can be easily performed. In addition, since the bottom wall can be easily processed with high precision, the displacement characteristics are good, and there is an effect that a protective layer, an insulating layer, and the like on the electrode surface need not be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining an embodiment of an ink jet recording apparatus according to the present invention, and FIG. 2 is a diagram for explaining the operation of a head unit according to the present invention. FIG. 3 is a cross-sectional view for explaining a head processing method;
FIGS. 4 to 7 are views showing another embodiment of the head section of the present invention. 1 ... Discharge port plate, 2 ... Piezoelectric vibrator, 3 ... Substrate, 4 ...
… Ink flow path, 5… flow path partition, 6… upper substrate, 7…
Drive electrode, 8: Common electrode, 9: Slit, 10: Partition member, 11: Bottom wall, 12: Discharge port, 13: Bottom wall layer.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor ▲ Ame ▼ Minoru Yamamoto 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company, Ltd. (72) Inventor Osamu Naruse 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6 Inside Ricoh Company, Ltd. (72) Inventor Toshiharu Hirata 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company Limited (56) References JP-A-59-159358 (JP, A) JP-A-63-129173 (JP, A) JP-A-63-252750 (JP, A) JP-A-63-247051 (JP, A) JP-A-60-90770 (JP, A) (58) Int.Cl. ⁶ , DB name) B41J 2/045

Claims (1)

(57) [Claims] An ink flow path communicating with the discharge port, a flow path partition for individually dividing the ink flow path, and an ink supply unit communicating with the ink flow path; A piezoelectric vibrator for causing deformation in the portion is provided, and by driving the piezoelectric vibrator, a deformation is generated at a root portion of the flow path partition, causing a displacement in the flow path partition, and causing a change in the ink flow path. In an ink jet head that generates a pressure change to discharge ink droplets from the discharge ports, selectively driving one part of the piezoelectric vibrator corresponding to the ink flow path to form the corresponding ink flow path An ink jet recording apparatus characterized in that a displacement is caused on both side walls of the flow path forming the ink.