JPH02289351A - Recording head and recording device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Ki 4 standing The present invention relates to an inkjet recording head.

For example, it is applied to fluid elements, pumps, valves, etc.

6 and 7 are configuration diagrams of a conventional pressurizing on-demand multi-head, with FIG. 6 showing a sectional view and FIG. 7 showing a top view thereof. In the figure, 21 is an upper plate, 22 is an electrostrictive vibrator, 23 is an ink supply path, 24 is an ink supply side flow path, 2
5 is an ink pressurizing liquid chamber, 26 is a substrate, 27 is a channel, 28 is a nozzle, 29 is a common liquid chamber, and 30 is an ink supply hole.

This pressurized on-demand multi-head pressurizes the liquid chamber using the #i electrostrictive vibrator and ejects ink from the nozzle.

Furthermore, Japanese Patent Application Laid-Open No. 63-307959 discloses a method in which a beam is bent by electrostatic force to block a nozzle, a so-called valve is formed into an oval shape, and the gas flow of sublimable dye is released or blocked to perform control. It is something that exists.

Further, an elastic movable part is provided in the liquid chamber, a first electrode is disposed on the elastic movable part, and a voltage is applied between the first electrode and the 211th pole provided on the inner wall of the liquid chamber to deform the elastic movable part. A device that ejects droplets from a nozzle has also been proposed. However, conventional multi-heads using electrostrictive vibrators require electrostrictive vibrators of a certain size to obtain the ink jetting force, and are not suitable for increasing the density of foreign products. Also.

A method that applies electrostatic force to a cantilever and ejects ink in a liquid chamber from a nozzle due to the displacement of the cantilever has somewhat insufficient driving force, requires high voltage, increases the area of the cantilever, and reduces the gap between electrodes. I needed to make it smaller. If the voltage is high, the cost of the power supply will increase, and the cost of the switching drive circuit will also increase. Also.

The larger the area of the cantilever, the more difficult it becomes to achieve high density. Furthermore, if the electrode gap is made smaller,
In addition to being more likely to cause dielectric breakdown between the electrodes, problems occur such as making it difficult to configure and process the gap to maintain it. Furthermore, it is clear that it is difficult to greatly increase the dielectric constant of the ink itself due to the characteristics of the ink.

As described above, the conventional driving force based on electrostatic force is very small, and in order to obtain a predetermined driving force, costs, high density/change, difficulty of processing, etc. are sacrificed.

The present invention was made in order to solve the above-mentioned drawbacks, and it is necessary to increase the density, increase the driving force, and have sufficient ejection force, and also to prevent sudden changes in dielectric constant due to heat. Matter first. sealed between the second electrodes, and the first. By constantly applying a DC bias voltage between the second electrodes and heating the vicinity of the individual electrodes, the dielectric constant is rapidly increased and the DC bias voltage can be used in pulses, allowing the use of low operating voltages for heating pulses. The purpose of this invention is to provide an ink sheet recording head that achieves a significant reduction in price.

In order to achieve the above object, the present invention provides (1) a recording body and a first structure in which part or all of a flow path structure constituting a flow path of the recording body is a vibrating member. 'A positive electrode and a second electrode provided outside the flow path corresponding to the first electrode, and by applying a voltage to the first electrode and the second electrode, the vibrating member By displacing the recording medium and increasing the volume of the flow path, a moving force is applied to the recording medium so that the recording medium adheres to the recording medium and is recorded.

Furthermore, (2) a substance having a relative dielectric constant is filled between the first electrode and the second electrode, and (3)
1st. A material whose dielectric constant changes greatly due to heat is sealed between the second electrodes, and the first Ink is ejected by the electrostatic force between the second electrodes, and (4) the first. A material whose dielectric constant changes greatly due to heat is sealed between the second electrodes, and the first.
The electrostatic force between the second electrode and the first. It is characterized in that ink is ejected by electrostatic force between the second electrode and the third electrode. Hereinafter, the present invention will be explained based on examples.

FIG. 1 is a configuration diagram for explaining one embodiment of a recording head according to the present invention, and FIG. 2 is a sectional view taken in the longitudinal direction of FIG. 1. In the figure, 1 is a side wall, 2 is a top plate, 3 is a diaphragm, 4 is an individual electrode, and 5 is a common electrode.

6 is a substrate, 7 is a flow path, 8 is a forced liquid crystal, 9 is a large opening, 10 is a common liquid chamber, 12 is a power source, 13 is a spout, 1
4 is a gap and 15 is paper.

The side wall 1 and the diaphragm 3 constituting the ink flow path 7 are made of silicon by etching, photolithography, or the like. Further, the upper part of the flow path 7 is closed by the top plate 2. One end of the flow path 7 serves as an ink jet port 13. The other side is a common liquid chamber 10 made up of a top plate. Ink is supplied to the common liquid chamber 10 from an ink tank (not shown). Individual electrodes 4 are arranged on the back side of the diaphragm 3 (not on the flow path side), and each maintains insulation. Further, a common electrode 5 is placed on the substrate 6 with an appropriate cap 14 placed opposite the individual electrodes 4, and is connected to a power source 12. A gap 14 between the individual electrodes 4 and the common electrode 5 is filled with a ferroelectric liquid crystal 8 and is opened to the atmosphere through an air opening 9. In addition, the air opening should be as large as possible.

Also, it is preferable to have multiple locations rather than just one location.

When a voltage is applied between the individual electrodes 4 and the common electrode 5 in the Infusiera 1 to the recording heel 1- having such a configuration, the diaphragm 3 is deflected by electrostatic force, the volume of the flow path 7 is increased, and the ink is Supplied from the common liquid chamber. Here, when the applied voltage is turned off, the sagging diaphragm 3 returns to its original state and pressurizes the ink within the flow path 7. Due to the pressurized energy, the ink is ejected as ink droplets through the ejection port 13.
It adheres to the paper 15 and is recorded. Since the ferroelectric liquid crystal 8 within the gap 14 has fluidity, it follows the deflection of the diaphragm 3. However, this ferroelectric liquid crystal 8 is a load to the motive force generated in the diaphragm 3, and it is desirable to reduce the load.Also, the movement of the ferroelectric liquid crystal 8 between the individual electrodes is desirable. Third, to eliminate interference caused by
Needless to say, it is better to attach a partition plate 11 shown in the figure to partition each electrode. In the embodiment of the present invention, a ferroelectric liquid crystal is interposed between the electrodes, but it is of course advantageous that a suitably selected material can be interposed instead of this.

4 and 5 show another embodiment of the present invention, in which FIG. 4 is a front view and FIG. 5 is a side view, 16 is a nozzle plate, and 17 is an ink supply path. . In this embodiment, since the jet nozzle 13 is located in the direction of displacement of the diaphragm 3, the jetting efficiency is good.

Next, another embodiment of the present invention that is an improvement on the embodiment described with reference to FIG. 1 will be described. That is, in FIG. 1, the diaphragm 3 is displaced by a voltage pulse 12 (direct current is applied in FIG. 1, but a pulse is appropriate in this case) applied between the individual electrode 4 and the common electrode 5, but the diaphragm 3 is side wall 1
The diaphragm 3 is connected integrally with the diaphragm 3 or by adhesive, etc., and in order to obtain sufficient vibration displacement equal to the condition that the diaphragm 3 is fixed around the periphery, it is necessary to increase the peak value of the applied voltage pulse, which increases the cost of the open circuit. . FIG. 8 is a diagram illustrating electrostatic attraction acting on parallel flat plates. The electrostatic attractive force Pa acting between two electrodes is expressed by the following formula.

Here, ■ is the applied voltage, d is the distance between the electrodes, and ε is the dielectric constant, and the dielectric constant ε is expressed by the following formula.

* ε=ε, ε (2) Here, ε is the permittivity of vacuum, and ε is the relative permittivity. Therefore, when the electric field strength E (=V/d) is constant, the electrostatic attraction becomes larger as the material has a larger relative dielectric constant.

FIG. 9 is a diagram showing the temperature change in the relative vI dielectric constant.

As a substance whose dielectric constant increases rapidly due to temperature changes, for example, a jelly-like mixture of nitrobenzene (dielectric constant 34) and barium titanate (dielectric constant 16,000) is used, and TII =25℃ to T, = 1
The relative dielectric constant changes by 200 to 500 due to a temperature change of 20°C.
degree is obtained. Furthermore, when various types of ferroelectric liquid crystals are used, the relative dielectric constant changes from several hundred to several thousand.

FIG. 10 shows still another embodiment of the present invention,
In the figure, 31 is a heating element, 32 is an upper plate, 33 is a flow path, 34 is a nozzle, and 35 is a heating element drive pulse.

36 is a power supply, 37 is a lower plate, 38 is a dielectric material, 39 is a second
The electrodes include a first electrode 40, a spacer 41, and a vibrating member 42.

The upper plate 32 and the vibrating member 42 form a flow path 33 corresponding to the nozzle 34 (indicated by a dotted line). A dielectric material 38 whose relative permittivity changes rapidly due to temperature changes is sealed between the vibrating member 42 and the lower plate 37, and two electrodes 1 and 2 are arranged therein. An electrostatic voltage is applied between the two electrodes, and the above (1
) acts, but since the dielectric constant in equation (2) is small, the electrostatic attraction is small, and the wall of the flow path portion of the vibrating member 42 is slightly displaced or not displaced. The vibrating member 42 is provided with a heating element 31 corresponding to each flow path.

By applying the heating element driving pulse, the :JI electric material near the heating element is rapidly heated, and the dielectric constant increases rapidly as shown in FIG. Therefore, the electrostatic attractive force expressed by equation (1) increases, the vibrating member 42 corresponding to the flow path 33 is displaced, and the flow path volume is expanded. When the heating element drive pulse 35 is turned off, the vibration section 4
2 returns, the pressure inside the flow path is increased and ink is ejected from the nozzle 34.

FIG. 11 shows yet another embodiment. The principle of displacement of the vibrating member is the same as that shown in FIG. 1st.
Due to the potential difference between the second electrode +v1 and the potential of the third electrode -■, there is a potential difference of v1+Vx in the ink in the flow path, and a Coulomb force acts on the ink to form a meniscus at the tip of the nozzle. .

Due to the increase in optical path volume when voltage pulses are applied to the heating element,
The ink is once drawn into the nozzle, but when the volume of the flow path decreases, it is ejected from the nozzle. At this time, the potential difference V t +
The ink droplet speed is accelerated by the electrostatic force (Coulomb force) caused by Vz, and high-speed and stable ink ejection can be realized.

As is clear from the above description, according to the present invention, the drive generation part is configured outside the flow path rather than inside the flow path, and the characteristics of the ink (e.g. relative permittivity, insulation, etc.) There is no need to consider. In other words, the various characteristics of ink can be determined with image quality as the first priority, and are no longer influenced by the characteristics of the device. This is an excellent effect in terms of image quality. Also, as a material with a high dielectric constant that is used to improve electrostatic force.

That is, glycerin is 42. '5. Saniletsk MD
(Sanyo Chemical Industries, Ltd. product name) is 77.5. When you need even more power, the most convenient option is
It can be said to be a ferroelectric substance. Among these, some ferroelectric liquid crystals have a dielectric constant exceeding 4,000 to 6,000, and the fact that they are fluids is also a favorable condition for implementing the present invention. By interposing such a ferroelectric liquid crystal between the electrodes, a high detour force commensurate with its dielectric constant can be obtained.

In addition, by adopting such a configuration, it is only necessary to create an electrode pattern for the vibration generating part, and for example, there is no need for an electrostrictive vibrator required for a conventional multi-head, and a high quality area ratio is possible. It became. Furthermore, low voltage agitation is possible, making it possible to reduce costs, and high-speed, stable ink ejection becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram for explaining one embodiment of a recording head according to the present invention, FIG. 2 is a cross-sectional view taken in the longitudinal direction of FIG. 1, and FIG. FIGS. 4 and 5 are diagrams showing other embodiments of the present invention, and FIGS. 6 and 7 are diagrams showing the configuration of a conventional pressurized on-demand multiplier. . FIG. 8 is a diagram for explaining the electrostatic attraction acting between parallel plates, FIG. 9 is a diagram showing changes in relative dielectric constant with temperature, and FIGS. It is a figure showing an example. ■... Side wall, 2... Top plate, 3... Vibration plate, 4...
・Individual m pole, 5... Common electrode, 6... Substrate, 7...
Channel, 8... Ferroelectric liquid crystal, 9... Atmospheric opening, 1
o... Common liquid chamber, 11... Partition plate, 12... Power supply,
13... spout, 14... gap, 15... paper. Figure 1

Claims (1)

[Claims] 1. A recording body, a first electrode in which part or all of a flow path structure constituting a flow path of the recording body is a vibrating member, and a first electrode outside the flow path. and a second electrode provided corresponding to the electrode, and by applying a voltage to the first electrode and the second electrode to displace the vibrating member and increase the volume of the flow path,
A recording head characterized by applying moving energy to the recording medium to cause the recording medium to adhere to the recording medium and perform recording. 2. The recording head according to claim 1, wherein a material having a relative dielectric constant is filled between the first electrode and the second electrode.