JPH06106725A - Recording method by electrostatic deformation type ink jet and electrostatic deformation type ink jet head - Google Patents

Abstract

PURPOSE:To provide a new ink jet method which uses a water-color ink with high safety, can be controlled by a low voltage, can use a high driving frequency, and in addition, for which a slit or multi-nozzle can be used by a simple structure. CONSTITUTION:A nozzle 13 is formed by confrontingly arranging a rigid electrode 11 and elastic electrode 12, and a tinted liquid 14 with a high dielectric constant is put in the nozzle. A voltage is applied between the rigid electrode 11 and elastic electrode 12, and the elastic electrode is made to deform toward the rigid electrode by an electrostatic attracting force which is applied between opposite polarity charge phases which are induced at both electrodes, and particles 14a of the tinted liquid are made to fly from the leading end of the nozzle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording system using a multi-nozzle or slit, and in particular,
The present invention relates to a new type of inkjet system in which ink is ejected by electrostatic deformation of an elastic electrode.

[0002]

2. Description of the Related Art An electrostatic suction method is one of the typical ink jet recording methods. This method has the advantages that very small ink droplets can be formed and that multi-nozzles can be easily formed.

FIG. 18 shows the principle of the electrostatic attraction method. In FIG. 1, reference numeral 1 is a large number of recording electrodes separated by an insulator, and 2 is a single counter electrode corresponding to the whole of a large number of recording electrodes 1. +3 kv can be independently applied to each of the recording electrodes 1 and the common counter electrode 2. There is a gap between the electrodes 1 and 2, the recording ink 1 is supplied to the recording electrode 1 side of this gap, and the recording paper 4 is arranged on the counter electrode 2 side.

When +3 kv is applied to an arbitrary recording electrode 1 (the recording electrode on the center and the left side in this figure), the meniscus 3a of the oil-based ink on the electrode is charged (+) and attracted by electrostatic force. . At this time, the meniscus 3a is vertically polarized from the recording electrode 1 toward the counter electrode as shown in the figure,
An electric field formed by the potential difference between the recording electrode 1 and the counter electrode 2 acts on the polarized charge, and the Coulomb force causes the ink particles 3b to fly and reach the recording paper 4 to print an image.
(Note: Coulomb force is applied to the injected charge injected from the recording electrode in addition to the polarization charge.)

However, this electrostatic attraction method has the following problems. (1) The applied voltage is as high as several kilovolts, and even the improved type requires a high voltage of about 500 volts. The voltage that cannot be controlled by the IC not only increases the size of the circuit, but also increases the cost because general-purpose parts cannot be used. (2) Further, since the ink used is oily, there is a problem in safety.

(3) Since the oil-based ink has high resistance and low dielectric constant, the relaxation time of polarization is slow and the response frequency is low. (4) Since the ink particles are uniformly and strongly charged, the Coulomb force acts between the ink particles and the resolving power deteriorates when the flight distance is increased.

(5) Since the electrostatic attraction force is small, the static meniscus of the ink is formed at the tip of the slit or nozzle by applying a static pressure of a limit that does not jump to the ink in advance, but this is broken even by a slight vibration. It becomes an abnormal image. (6) A magnetic ink jet using a magnetic ink has been proposed, but the magnetic ink is colored by itself and thus cannot be colored.

As a method similar to the electrostatic suction method, E
R-fluid ink jets are known. ER fluid (Elec
The tro-Rheologilcal fluid) is a dispersion of fine particle powder in an oil dispersion medium, and has the property of increasing the apparent viscosity several tens to several hundreds of times when an electric field is applied. Therefore,
When the ink consisting of the ER fluid is ejected from the nozzle and a voltage is applied between the electrodes while checking the timing, the shearing force of the ink increases and the flow of the ink is stopped.

However, even with this method, there are problems such as precipitation of the dispersed phase, and the above-mentioned drawbacks of the oil-based ink cannot be solved.

[0010]

SUMMARY OF THE INVENTION The present invention is to eliminate all the above-mentioned drawbacks. That is, to provide a new inkjet method that uses highly safe water-based ink, can be controlled at a low voltage, can use a high driving frequency, can be colored, and can have slits and multi-nozzles with a simple structure. It is in.

[0011]

In order to achieve the above object, the present invention provides a nozzle in which a rigid electrode and an elastic electrode are opposed to each other, and ink having a high dielectric constant is put in the nozzle. A voltage is applied between the rigid electrode and the elastic electrode to deform the elastic electrode in the direction of the rigid electrode by an electrostatic attractive force acting between charges of different polarities induced on both electrodes, and the nozzle A feature is that the ink is ejected from the tip.

Alternatively, an elastic body having a high dielectric constant is sandwiched between a signal electrode and a counter electrode, at least one of which is made of an elastic body, and a voltage is applied between both electrodes to induce different polarities in both electrodes. The elastic electrode is deformed toward the electrode on the other side by the electrostatic attractive force acting between the electric charges, and the ink in the nozzle in contact with the free interface of the elastic body having a high dielectric constant is ejected from the nozzle. It may be configured.

Further, a nozzle is formed between the signal electrode, at least one of which is made of an elastic material, and the counter electrode, and a voltage of the same polarity is applied to the both electrodes to induce electric charges of the same polarity induced in both electrodes. An electrostatic repulsive force acting between the elastic electrodes deforms the elastic electrodes outward, and the negative pressure causes ink to be filled in the nozzles, and a voltage of opposite polarity is applied to the electrodes to induce a difference between the electrodes. The ink in the nozzle may be ejected from the nozzle by an electrostatic attraction that acts between polar charges.

Further, ink having a high dielectric constant is placed in a chamber formed between electrodes in which at least one is made of an elastic material and a photosensitive layer is carried in at least one of the electrodes, and a voltage is applied between both electrodes to make the elastic electrode. Form a weak electric field that does not substantially deform, but is sufficient to move charges in the photoreceptor layer in a short time. Is exposed to light to generate photocarriers in the exposed portion, which is moved in the photoconductor layer to form a strong electric field, and the electric field is applied to the electric charge in the elastic electrode, and the elastic electrode is placed inside the chamber. It may be configured such that the ink is ejected from an orifice formed in the chamber by being deformed toward the front.

Further, ink having a high dielectric constant is placed in a chamber formed between the electrode having the photoconductor layer and the conductive elastic body, and a voltage is applied between the conductive elastic body and the electrode. The conductive elastic body does not substantially expand or does not eject ink from the ink chamber even if it expands, but forms a weak electric field sufficient to move charges in the photosensitive layer in a short time. Then, at the same time or after that, the photoconductor layer is imagewise exposed by a light emitter to generate a photocarrier in the exposed portion,
A strong electric field is formed by moving in the photoconductor layer, and the strong electric field expands the elastic body to the inside of the ink chamber by the electrostatic attraction acting on the electric charge in the conductive elastic body. Ink is projected from the orifice, then both electrodes are short-circuited to extinguish the electric field and the negative pressure generated when the conductive elastic body returns to the original state cuts the ejected ink and refills the ink chamber at the same time. It may be configured.

[0016]

[Function] When a voltage is applied between the elastic electrode and the electrode facing the elastic electrode, an electrostatic attractive force (Coulomb force) acts between the positive and negative charges applied to the both electrodes to oppose the elastic electrode. The ink is deformed toward the electrode to increase the pressure of the ink in the nozzle, and liquid particles are ejected from the nozzle.

When an elastic body having a high dielectric constant is sandwiched between the elastic body electrode and an electrode facing the elastic body electrode, and the free interface of the elastic body having a high dielectric constant is exposed to the nozzle, the elastic body is also ejected from the nozzle. Ink particles fly. In this case, the dielectric constant of the ink does not matter and any ink can be used.

When at least one of the signal electrode and the counter electrode is made of an elastic material and a voltage of the same polarity is applied to both electrodes, an electrostatic repulsive force acting between the electric charges of the same polarity induced in both electrodes. By this, the elastic electrode can be deformed to the outside, and the ink can be filled in the nozzle by the negative pressure in the nozzle space generated at that time. The operation is faster than the piezo method, and a small nozzle can be formed. Further, unlike the bubble jet, it does not require heating and cooling.

Further, if the photoconductor layer is formed on the electrode facing the elastic electrode, the elastic electrode can be electrostatically deformed by the irradiation of light from the light emitting body. Instead of this elastic electrode, a conductive elastic body may be used to cause electrostatic deformation. Ink droplets can be caused to fly by these electrostatic deformations.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of an electrostatic deformation type inkjet according to the present invention. In the figure, 11 is a rigid electrode,
Reference numeral 12 represents an elastic electrode. The nozzle 13 formed between the two electrodes 11 and 12 has a high dielectric constant and water-based ink 1
4 is supplied. Reference numeral 15 indicates a recording sheet.

A voltage is applied between each rigid electrode 11 and elastic electrode 12. In this embodiment, the rigid electrode 11 is grounded,
The elastic electrode 12 is connected to (+). Positive and negative charges are induced (charged) in these electrodes, and the elastic body electrode is deformed in the direction of the rigid body electrode 11 as shown in FIG. Slit or nozzle 1 formed between both electrodes by applying pressure to 14
The particles 14a of the ink are ejected from 3.

At least in the present invention, it is not necessary to distinguish between the slit and the nozzle, and the term "nozzle" in the present invention includes the slit unless otherwise specified.

Ink droplets 3b formed by the electrostatic suction method
Are charged as described with reference to FIG. 18, and repel each other due to the Coulomb force with the ink droplets of the adjacent pixels and shift left and right from the orbit, degrading the image. On the other hand, the flying ink particles 14a in the present invention are not charged. Therefore, unlike the conventional electrostatic attraction method, the particles do not interfere with each other. This is the first advantage of the present invention.

In the conventional electrostatic attraction method, a force acts on the ink itself, so that the characteristics of the ink are limited. However, in the present invention, since the ink is ejected by the force acting on the electrode, there is less limitation on the ink 14 and the water-based ink is used. It is safe to use. This is the second advantage of the present invention.

Further, in the conventional electrostatic attraction method shown in FIG. 18, since the recording paper 4 is passed between the electrodes 1 and 2, a gap of at least 0.8 mm is required between the electrodes, which is why A high voltage of kv is required. In the present invention, since the distance between the electrodes may be 100 μm or less, the applied voltage may be 1000 v or less. This is the third advantage of the present invention.

Since the ink used in the electrostatic attraction method has a high resistance and a low dielectric constant, the relaxation time of polarization is slow, it can be used only at a low driving frequency, and the printing speed is slow. On the other hand, in the present invention, the printing time is determined not by the ink relaxation time but by the time constant of charging / discharging the electrode. However, since the electrode area is very small, the time constant is small and high-speed printing is possible. This is the fourth advantage of the present invention.

In the conventional method, a force acts not only on the recording electrode to which a signal is applied but also on the adjacent region thereof. However, in the present invention, if the common electrode is made rigid, even if a force acts on the adjacent portion, that Since the part is not deformed, only the electrode to which the signal is applied is deformed, and the image does not have a blur problem. This is the fifth advantage.

One of the conventional methods is bubble ink jet, which heats the ink to about 300 to 400 ° C.
There is a drawback that the life of the ink is shortened. But,
According to the present invention, since heating is not necessary, such a problem does not occur. This is the sixth advantage.

In the bubble ink jet system, the size of the ink droplet cannot be changed, but in the present invention,
The amount of displacement of the elastic electrode can be changed by changing the recording applied voltage, the amount of induced charge, and the electrostatic attractive force acting on the electrode, which makes it possible to change the size of ink particles, that is, ink droplets. Can be changed. This is the seventh advantage of the present invention.

The difference between the conventional electrostatic attraction method and the electrostatic deformation method of the present invention has been qualitatively described above. Next, a quantitative explanation will be given based on electrical theory. Generally, the electrostatic force received by a dielectric can be obtained as the Coulomb force of the electric field at that point that acts on the polarized charge, but it is easier to consider it by Maxwell's stress.

FIG. 2 shows a configuration model of a conventional electrostatic attraction method, in which 1 is a recording electrode and 2 is a counter electrode. Both electrodes 1,
Between the two, water 5 as a substitute for the oil-based ink 3 is provided below.
There is air on the side of the counter electrode 2 instead of the recording paper 4 and the like. That is, the recording electrode 1 and the counter electrode 2 form a horizontal parallel plate capacitor, and the lower half thereof is filled with water 5 and the upper half thereof is filled with air 6.

FIG. 3 is a constitutional model of the present invention, in which the rigid electrode 11 and the elastic electrode 12 have a thin insulating layer 1 on the surfaces facing each other.
1'and 12 'are formed, and an ink 14 (here, water is used) is filled between them. In the case of the present invention, both electrodes 11 and 12 form a vertical parallel plate capacitor, and the space between the electrodes is filled only with water.

In FIG. 2, Maxwell's stress f1 for shrinking air per unit area and stress f2 for shrinking water similarly.
When finding the ^{door, f1 = εoE1 2/2 (} 1) f2 = εoεrE2 2/2 (2)

Where E1: electric field in air E2: electric field in water εo: permittivity of air εr: relative permittivity of (water)

In FIG. 2, the force fa acting on the liquid surface is f1.
And f2. fa = f1-f2 = εo (E1 ² −εrE2 ² ) / 2 (3) Next, the following relationship exists between E1 and E2. εoE1 = εoεrE2 (4)

When the thickness of air and water is d / 2, the relationship of Vo = E1d / 2 + E2d / 2 (5) is established between the applied voltage V ₀ and E1 and E2. Substituting (4) into (5) and rearranging, E2 = 2Vo / (d (εr + 1)) (6)

Substituting this into (4) and E1 = 2εrVo / (d (εr + 1)) (7) (6), (7) into (3), the electrostatic force fa acting on the water surface in FIG. Is required. The final expression is shown with the middle omitted.

Fa = (εoεr (εr-1) Vo ² ) / d ² (εr + 1) ² (8) In the case of water, the relative permittivity εr is 80 and is sufficiently larger than 1 (εr
Since ≧ 1), the equation (8) can be approximated by the following equation (9). fa = εoVo ² / d ² (9)

In the case of the present invention shown in FIG. 3, the electrostatic attractive force fb acting on both electrodes is the electrostatic attractive force itself acting on the electrodes on both sides of the parallel plate capacitor, and this force is as follows from the textbook of electromagnetics. It is given by the formula (find the force per unit area). fb = (εrεoVo ² ) / (2d ² ) (10)

Vo = 3000v, d = 0.8 mm in the conventional system,
Substituting Vo = 100 v and d = 0.1 mm into the present invention, fa and f
Find b. However, εr = 80, εo = 8.85 × 10 ^-12 (F /
m), S = 1 m ² . fa = 1.2 × 10 ² (N / m) fb = 3.5 × 10 ³ (N / m)

Therefore, it can be seen that the present invention can obtain a much larger force. Of course, in the conventional electrostatic suction method, the force is directly applied to water, and in the present invention, the force is applied to the elastic electrode, and there is a loss when it is transmitted to the ink, but it is large enough not to cause a problem. There is a difference.

The theoretical and quantitative comparison has been completed as described above, and then specific items in the case of implementation will be described.

The shape of the electrode is not limited to the single gun nozzle,
It can be a multi-head or a slit. In the case of a slit, one electrode can be a common electrode.
Then, a signal voltage is applied to the other multi-stylus sequentially or simultaneously to cause the ink to fly between the signal-bearing electrode and the common electrode. In this case, it is expected that the common electrode will be deformed weaker than that at the location corresponding to the adjacent signal electrode, but this can be solved by making the common electrode a rigid body.

In the apparatus shown in FIG. 4, a nesa glass is used as the rigid electrode 11, an aluminum vapor deposition Mylar film having a different thickness from that of the nesa glass is prepared as the elastic electrode 12, and a high resistance phenol resin is dried on both electrode surfaces. The film thickness of
Overcoat by spraying to a thickness of 0.2 μm. The reason why the insulating coating is performed is to prevent the ink from leaking when the voltage is applied as it is because the electric resistance of the ink is very low. However, if the coat is too thick, the voltage will be consumed there. Therefore, the above-mentioned film thickness is the result of the thinnest coating within the range that does not leak. Lead wire was attached to the part that was not overcoated with copper tight.

As shown in the figure, both electrodes are laminated face to face with a Mylar film having a thickness of 100 μm as spacers 16, and 99 g of pure water as ink 14 having a high dielectric constant is provided therebetween.
Put black ink with 1g of carbon black dispersed in
A voltage of +100 v was applied via the switch. Then,
It was confirmed that the ink 14 flew upward from the nozzle 13. Aluminum vapor deposited mylar film has a thickness of 12 to 25μ
m was appropriate. If it was thicker than that, it was difficult to be deformed, and if it was thinner, it could not be applied evenly.

FIG. 5 shows a second embodiment of the present invention. This embodiment is characterized in that an elastic body 23 having a high dielectric constant is sandwiched between the signal electrode 21 and the counter electrode 22. Either or both of the signal electrode 21 and the counter electrode 22 are made of an elastic body. In this embodiment, the signal electrode 21 is made of an elastic body. This sandwich is fitted into the frame 24, and the frame 24 is formed with the nozzle 25 in contact with the free interface of the elastic body 23.
The upper end of the nozzle 25 is narrowed to form an opening 25a,
Ink 26, which is an aqueous ink, is filled in the nozzle.

When a voltage is applied between the electrodes 21 and 22,
The signal electrode 21 formed of an elastic body is deformed by the Coulomb force as shown in the left side of FIG. 5, and the intermediate elastic body 23 is deformed to project into the nozzle 25. The protrusion of the elastic body 23 causes the particles 26 a of the ink 26 to fly to the recording paper 27.

While the ink 13 of the embodiment shown in FIG. 1 required a high dielectric constant, the ink 26 flies under mechanical pressure in this embodiment, so that the dielectric constant has no magnitude. no problem, it can also be used in any ink, including water ink.

In addition, in the conventional electrostatic suction method, since the electrostatic attraction is small, it is necessary to apply the last static pressure that does not cause the ink to eject in advance to form the meniscus of the ink at the tip of the nozzle. Therefore, it is easily affected by vibration and the like, and lacks stability. On the other hand, in the present invention, since a sufficient force can be generated to fly the ink, it is not necessary to form a meniscus, and the vibration is strong.

In the apparatus shown in FIG. 6, Nesa glass is used for the counter electrode 22, and a polyester film 28 having a thickness of 100 μm is first attached to this conductive surface with a space (1 mm in this example), and then, After drying a solution of fine powder of barium titanate (BaTiO ₃ ) and silicone rubber (BY25-809: manufactured by Toray Dow Corning Silicone Co., Ltd.) in toluene at a solid content ratio of 7.5 wt% at a ratio of 4: 6. Film thickness is 100
The elastic body 23 having a high dielectric constant is formed by spray coating so as to have a thickness of .mu.m, and a thin insulating layer is coated as in FIG. 4, and then the signal electrode 21 is formed thereon by mesh hatching.
Aluminum was vapor-deposited as.

When measured by a surface potential method used in electrophotography before aluminum vapor deposition, the relative dielectric constant of this BaTiO ₃ -containing silicone rubber layer was about 100. About half (2 mm in this example) of the upper side of this rubber layer was cut out, and the same 100 μm thick polyester film 29 as above was adhered to the entire surface including the part (however, the silicone rubber part was not adhered).

A lead wire was connected to the Nesa glass and the aluminum vapor deposition electrode with copper tight, the aluminum electrode was grounded, and the Nesa glass electrode was connected to a DC power source through a switch.

Phthalocyanine dye (Fastgen blue 8110)
Was dispersed in pure water at a solid content ratio of 4 wt% to obtain a blue aqueous ink. When this blue ink was put into the nozzle 25 whose rubber layer was cut off with a dropper as the ink 26 and a power supply of 100 V was applied and the switch was turned on, it was possible to observe that the ink 26 flew out from the tip of this nozzle 25. When the power supply voltage was lowered and observed with a magnifying glass from the Nesa glass surface, it was confirmed that the tip of the elastic body 23 (rubber layer) was deformed according to the voltage.

According to the embodiments shown in FIGS. 5 and 6, the water-based ink is used at a very low signal voltage and at a very high frequency as compared with the conventional electrostatic attraction method, and the vibration is affected. It can be printed without.

Next, a method of supplying ink to the nozzles shown in the above embodiment will be described. Generally, a piezo method has been generally used as a method for supplying ink to such nozzles. In this method, a bimorph type piezo element is vibrated, ink is ejected from an orifice when the ink chamber contracts, and ink is replenished from an ink tank when the ink chamber expands to prepare for the next ejection.

However, the piezo element has a displacement of 0.1 to 1 μm.
Since it is as small as m, the area of the piezo element becomes large, and the number of multi-heads is limited to 9 to 24 nozzles, and it is impossible to make several thousand heads necessary for simultaneous writing on one line. In addition, although it has a simple structure, since the amount of displacement is small, the negative pressure is small, replenishment time is required, and further, since the piezo element (lead zirconate-lead titanate, etc.) is heavy,
The response speed is as low as 2-3 KHz.

Another method is a bubble jet method, but since it is a heating and cooling process, the response speed is still several KH.
z. Also, the heater is about 1000 ℃, the ink is about 300 ~
Since the temperature reaches 400 ° C, the ink and head lack durability. Another problem is mechanical destruction due to shock waves because bubbles burst too quickly.

FIG. 7 is a sectional view of an ink jet head which has a quick response, a high ink supply capability, and can supply ink by a negative pressure without causing mechanical breakdown. Although specific numerical values are included, it is for the purpose of deepening understanding and is merely an example. A nozzle 33 is formed between the signal electrode 31 and a counter electrode 32 provided 100 μm away from the signal electrode 31, and the aqueous ink 34 is filled therein. At least one of the signal electrode 31 and the counter electrode 32 is formed of an elastic body. In this embodiment, the counter electrode 32 is an elastic electrode and the signal electrode 31 is a rigid electrode.

On the upper side of the counter electrode 32 and the lower side of the signal electrode 31, auxiliary electrodes 35 and 35 'are placed 0.5 mm apart. Between the counter electrode 32 and the auxiliary electrode 35,
There is a space 37 in which the counter electrode can be freely deformed. The auxiliary electrodes 35 and 35 'are always grounded, and +100 v is always applied to the counter electrode 32. The signal electrode 31 is grounded during the printing operation, and +100 V is applied during the replenishing operation.
These signal electrode 31, counter electrode 32 and auxiliary electrodes 35, 3
5'is fixed at the right end in the drawing by a resin block 36, and the resin block 36 is provided with an opening 33a of a nozzle 33.

The counter electrode 32 is formed by depositing aluminum on a thin polyester film (of about 4 to 12 μm). Other materials are known.

FIG. 8 shows the ink jet printing operation of FIG.
This will be explained with reference to (a) to (d). The printing operation starts when the replenishing operation is completed. At this time, the counter electrode 32 is deformed toward the auxiliary electrode 35 as shown in FIG. When the signal electrode 31 is changed from +100 v to 0 v,
As shown in FIG. 8 (b), the counter electrode 32 is charged with (+) and the signal electrode 31 is charged with a large amount of (-) charges. Transformed into
Ink particles (ink droplets) 34a are made to fly from the opening of the nozzle. As the deformation progresses, a strong elastic force is generated in the opposite direction, and the deformation stops when both the forces are balanced.
Here, the voltage of the signal electrode 31 is set to 0 as shown in FIG.
When the voltage is returned from v to +100 v, the strong electrostatic attractive force acting between both electrodes disappears, and the weak electrostatic attractive force acting between the strong elastic force and the grounded auxiliary electrode 35 remains. (This electrostatic attraction worked from the state of (a), but it was neglected because it was very small compared to the attraction with the rigid electrode 31.
Also, the electrostatic repulsive force acting between the signal electrode 31 and the counter electrode 32 is ignored. )

The signal electrode 32 begins to return to its original neutral state,
It deforms beyond the center line to the position shown in FIG. 8 (a) where the weak electrostatic attraction and elastic force with the auxiliary electrode 35 are balanced. At this time, since negative pressure is generated in the nozzle space 33, the ink 34 is replenished from an ink tank (not shown).

Here, the electrostatic attraction force of the return may be weak, and it will always deform if there is time, so the auxiliary electrode 35
Is not mandatory. A part of the housing surrounding the nozzle serves as a substitute.

However, when the auxiliary electrode 35 is provided, the electrostatic attraction force for returning is stronger, the replenishment time is shortened, and the replenishment amount is increased. Moreover, if the dielectric constant between the elastic electrode and the auxiliary electrode is increased, the electrostatic attractive force for returning is further increased. Since water is the representative of the elastic body having a high dielectric constant, the same ink 34 as in the nozzle may be filled in the space 37 between the signal electrode 32 and the auxiliary electrode 35. Reference numeral 37 'indicates water filled in a part of the space 37 from such a viewpoint.

When the space 34 is filled with the ink 34,
Since the ink 34 is pushed by the electrostatic force of return, the configuration shown in FIG. 9 is possible. That is, the one-way valves 38 and 38 'are arranged in the same direction on the auxiliary electrode 35 and the elastic electrode 32, and the one-way valve 38 on the auxiliary electrode 35 side is connected to the conduit 39 to the ink supply source. With such a configuration, when the counter electrode 32 is deformed to the signal electrode 31 side and the ink particles 34a are ejected from the starting state of FIG. 9 (a) as shown in FIG. 9 (b), the one-way valve is ejected. 38 is opened and ink is supplied from the conduit 39, and when the counter electrode 32 is deformed toward the auxiliary electrode 35 as shown in (c), the one-way valve 38 is closed and 38 ′ is opened, and the nozzle space 33 Is filled with ink.

When the auxiliary electrode 35 is provided in close proximity and the space between the auxiliary electrode 35 and the counter electrode 32 is filled with the water-based ink 34, the influence of the electrostatic attraction between them in the state of FIG. 8A is ignored. become unable. In such a case, it is desirable that the auxiliary electrode 35 and the counter electrode 32 during the printing operation have the same potential.

Next, the magnitude of the electrostatic attractive force during the printing operation is obtained. The electrostatic attractive force Pa acting between the signal electrode 31 and the counter electrode 32 is the same as fb in FIG. 3, and the force per unit area can be calculated from the equation (10) as follows: Pa = (εrεoVo ² ) / (2d ² )

Here, Vo = 100 v, d = 0.1 mm, εr
= 80, εo = 8.85 × 10 ^-12 (F / m), and S = 1m ² , Pa = 3.5 × 10 ³ (N / m ² ), which means that a very large electrostatic attraction can be obtained in the present invention. I understand. This force is at the same level as the pressure required by conventional piezo inkjets.

This force displaces the counter electrode itself and the ink in the future while accelerating the displacement, but in order to simplify the calculation, the area is 100 μm × 100 μm, and the counter electrode is 12 μm.
m, the ink on the front is 88 μm thick, the specific gravity is 1.0 for both, the average displacement is 50 μm, and the elastic force is zero,
The electrostatic force fa acting on the entire area is as follows: Fa = Pa * S = 3.5 * 10 < ³ > * (100 * 10 < ^-6 >) ² (N) = 3.5 * 10 < ^-5 > (N) where S is the area.

On the other hand, the mass m accelerated by this force is m = v × ρ = (100 × 10 ⁻⁶ ) ³ × 1 × 10 ³ (Kg) = 1 × 10, where v is the volume and ρ is the density. ^{It is -9} (Kg).

From the formula of mechanics, force f, mass m, acceleration α
In between, mα = f ∴α = f / m By substituting the values of fa and m previously obtained in this equation, the acceleration can be obtained. α = (3.5 × 10 ^-5 ) / (1 × 10 ^-9 ) = 3.5 × 10 ⁴ (m / s ² )

Since the displacement amount (x) is 50 μm, the time (t) required during this period can be obtained by the following equation. t = (2x / α) ^1/2 (sec) (initial velocity vo is zero) = (2 × 50 × 10 ^-6 /3.5 × 10 ⁴ ) ^1/2 = 5.3 × 10 ^-5 (sec)

At this time, the ink velocity v is v = α × t = (3.5 × 10 ⁴ ) × (5.3 × 10 ⁻⁵ ) = 1.9 (m / s ² ).

Actually, the amount of ink flying from the nozzle is about ⅛ of the ink moved in this calculation, so it seems that the speed becomes faster.

Next, the returning electrostatic attractive force fb is calculated with reference to FIG. As described above, the auxiliary electrode 35 is not always necessary, but it is assumed that it is parallel to the position 0.5 mm apart as shown in the figure. Both the signal electrode 31 and the counter electrode 32 have a (+) charge, and electrostatic repulsion acts between them, but this is not taken up here. Therefore, the counter electrode 3
The electrostatic attractive force fb acting between the electrode 2 and the auxiliary electrode 35 is obtained. fb = (εrεoSV ² ) / (2d ² ) (N) where V is the applied voltage, S is the area, d is the distance between the electrodes,
εr is the relative permittivity.

Then, V = 100 v, S = 100 × 10
^-6 m ² , d = 0.5 mm = 500 × 10 ^-6 m, εr = 1, εo =
Substituting 8.85 × 10 ^-12 (F / m), fb = (1 ² × 8.85 × 10 ^-12 × (100 × 10 ^-6 ) ² × 100 ² ) / (2 × (500 × 10 ^-6 )) ² = 1.77 × 10 ^-9 (N), which is five orders of magnitude smaller than the value in the previous printing mode.This force moves the elastic electrode 32 having a thickness of 12 μm, and its mass m is m = (100 × 10 ⁻⁶ ) ² × (12 × 10 ⁻⁶ ) × 1 × 10 ³ = 0.12 × 10 ⁻⁹ (Kg).

The acceleration αb at this time is αb = fb / m = 1.77 × 10 ^-9 /0.12×10 ^-9 = 14.8 (m / s ² ).

As for the return, if the average displacement x is 50 μm,
The time tb required during this period is tb = (2x / α) ^1/2 = (2 × 50 × 10 ⁻⁶ /14.8) ^1/2 = 2.6 × 10 ⁻³ (sec).

In order to make the return time faster, the electrostatic attractive force may be made larger, and for that purpose, the auxiliary electrode 35 may be positively arranged closer to each other. 0.5mm spacing
From 0 to 0.1 mm, fb = (1 ² × 8.85 × 10 ^-12 × (100 × 10 ^-6 ) ² × 100 ² ) / (2 × (100 × 10 ^-6 ) ² = 4.4 × 10 ^-8 (N)

Then, the acceleration αb becomes αb = fb / m = 4.4 × 10 ^-9 /0.12×10 ^-9 = 367 (m / s ² ), and the return time tb is tb = (2x / α) ^{1 / 2} = (2 x 50 x 10 ^-6 / 367) ^1/2 = 0.52 x 10 ^-3 (sec), which is 1/5.

In order to further reduce the length, the space between the auxiliary electrode 35 and the counter electrode 32 may be filled with a water-based ink having a high dielectric constant. In this case, fb is as follows: fb = (80 × 8.85 × 10 ^-12 × (100 × 10 ^-6 ) ² × 100 ² ) / (2 × (100 × 10 ^-6 ) ² = 3.5 × 10 ^-5 (N) Of course, since the size is the same as that of the printing operation, +100 V must be applied to the auxiliary electrode 35 during the printing operation.

The acceleration at this time is αb = fb / m = 3.5 × 10 ^-5 /0.12×10 ^-9 = 2.9 × 10 ⁴ (m / s ² ), and the return time tb is tb = (2x / α ) ^1/2 = (2 x 50 x 10 ^-6 /2.3 x 10 ⁶ ) ^1/2 = 5.9 x 10 ^-5 (sec), which is 1/80.

At this speed, recording becomes possible at a speed 100 times faster than that of a piezo element or a bubble jet.

11 and 12 show an embodiment in which a photoconductor is used in the present invention. FIG. 11 is an exploded perspective view of a photoelectrostatic deformation ink jet recording apparatus, and FIG. 12 is a side view. Although these figures include specific numerical values indicating dimensions, they are for the purpose of deepening understanding and are not limited thereto. This ink jet recording apparatus is completed by separately manufacturing an upper structure, a lower structure, and a side structure, and then bonding the three.

The upper structure is formed by arranging prisms 51, which are walls for separating a plurality of ink chambers arranged in parallel, at a pitch of 63.5 μm, and a thin elastic electrode 52 is bonded thereon. The prism 51 preferably has a moderately soft surface in order to absorb a shock wave, and specifically, polycarbonate, PET or the like is used. The elastic electrode 52 is formed by vapor-depositing an aluminum layer 52b on an elastic member 52a as a substrate and further overcoating a thin insulating layer 52c by a spray coating method. As the elastic member 52a, for example, a thin PET film, a silicone rubber film, or the like can be considered. The thickness of the elastic member 52a varies depending on the elastic modulus of the material, the required displacement amount, the durability, etc., but about 10 μm is suitable. As the material of the insulating layer 52c, it is preferable that the electric charge is leaked in a proper time rather than a high resistance, and a polyamide resin having a volume resistivity of about 10 ¹⁰ Ωcm is suitable.

The lower structure is formed by forming the inorganic photosensitive layer 54 on the electrode 53a made of the aluminum layer of the conductive glass 53 by vapor deposition, spray coating or plasma CVD. Organic photoconductors are not suitable for the present invention because of slow charge transfer. For inorganic photoconductors, Se-based and CdS-based photoconductors can be used satisfactorily considering the charge transfer speed, but amorphous silicon (a-Si: H) has a high transfer speed and its spectral sensitivity is close to that of visible light. It is optimal because it is insoluble in solvents. Dark resistance is too low for a usual Carlson method photoreceptor, and it is multi-layered as a countermeasure, but in the case of the present invention, since it is not necessary to charge, it can be used as a single layer at 10 ¹² Ωcm. Is. However, when there is charge injection from the substrate electrode, 2
Stratification is required.

The side structure is a structure in which a side plate 55 made of a PET film having a thickness of 25 to 100 μm is provided with a hole (orifice) 55a having a diameter of about 20 μm.

The ink jet head is completed by aligning the orifice 55a and fixing the side plate 55 to the elongated ink chamber 56 formed by mounting the upper structure on the lower structure. Ink 57 is supplied to the ink chamber 56 from a passage 58.

As shown, the height of the prism 51 is set to 80.
μm, photoconductor layer thickness 60 μm, ink chamber length 200
However, this value is not optimal because it simplifies the simulation calculation described later.

Next, the printing and ink supply method of the present invention will be described with reference to FIGS. 13 (a) to 13 (c). In addition, in FIG.
The side view of FIG. 11 is simplified and partly omitted.

First, the operation of the present invention will be described qualitatively and then quantitatively. FIG. 13A shows a preparation stage. After filling the ink chamber 56 with the ink 57, + 800v is applied to the elastic electrode 52. As shown in the figure, the elastic electrode 52 is charged with a small amount of holes and the photosensitive layer 54 as a photosensitive electrode is charged with the same amount of electrons. The holes of the elastic electrode 52 are subjected to an electric field formed by the electrons of the photosensitive layer 54, and the elastic electrode 52 receives a force directed inward. However, since the surface tension of the ink is larger, the ink 57 has an orifice. Never jump out of.

Next, in (b), when the light is emitted from the lower side of the photoconductor layer 54 through the Nesa glass 53 by the light emitting body 59 composed of the LED array, holes and electrons are generated in the vicinity of the photoconductor layer 54. Enters the aluminum layer 53a as a counter electrode, neutralizes and disappears with the electrons there, and the electrons move at high speed in the photoconductor layer 54 and stay on the surface of the photoconductor layer 54 as shown in the figure. The light emitting body 59 is configured by an electric circuit (not shown) so that the LED corresponding to a predetermined ink chamber emits light at a desired timing.

At this time, the amount of electrons and holes charged in the elastic electrode is several times as large as that in (a). The reason is that when this head is regarded as a capacitor, the distance between the electrodes is (ink layer + photosensitive layer) in (a), but it is reduced to only the ink layer in (b). If the number of holes is increased by 6 times, for example, the individual holes of the elastic electrode 52 receive 6 times the force of the electrons on the surface of the photoconductor layer 54, which is increased by 6 times. Receives 6 × 6 = 36 times as a whole. Further, if the ratio of the dielectric film thickness of the photoconductor layer to the ink layer is set to 2: 1 or more, the amount of electric charge before and after exposure is three times or more,
It is possible to change by more than 3 ² times by electrostatic force.

As a result, the ink chamber 56 is deformed so as to be compressed as shown in the figure, and as a result, the ink 57 begins to be ejected in a columnar shape from the orifice 55a. At this time, the deformation of the elastic body is stopped when the electrostatic attraction and the elastic force of the elastic body are balanced.

Next, at (c), the elastic electrode 52 is grounded.
(Exposure ended before that, but the result remains the same even if it continues for a while). At that moment, the holes of the elastic body electrode 52 and the electrons of the photosensitive layer 54 disappear, the electrostatic attraction applied to the elastic body electrode 52 becomes zero, and the elastic body electrode 52 is elastic force as shown in (c). Restore. At this time, a force for drawing in the ink 57 from the left and right acts on the ink chamber 56, the ink column ejected from the orifice 55a is broken, and an ink droplet 57a as shown in (c) is formed, and at the same time, the ink is replenished from the left side. To be done. It is because of the inertial force that the formed ink droplet 57a continues to fly in the left and right direction without being pulled back.

The ink column can be separated without grounding the elastic electrode. As in the conventional piezo method, when the elastic electrode is deformed inward in (b), the ink in the ink chamber is pushed out to the left and right, but the ink column protrudes on the right side and immediately stops, and the left side is a long supply pipe. This is because the ink continues to move due to inertial force, so that a suction force that acts toward the left is applied to the right side of the ink chamber. This is a scanning type exposure such as laser beam exposure, and is an effective method when the elastic electrode cannot be grounded within a certain time after the exposure.

The present invention can also be applied to a copying machine having an analog lens optical system, but in that case, since negative / positive is inverted, it is used as an output of a microfilm which needs to make a positive copy rather than a negative film. Good to use.

The qualitative explanation is completed above, and the operation of the present invention will be quantitatively supplemented below. However, since the exact calculation is very complicated, it is an approximate calculation based on some assumptions.

The conditions required for ejecting ink are
It is the force, the amount of displacement, and the rise time of the force. Show for reference
For example, in the conventional piezo method, the force is several tens.^FourN / m², The displacement is
About 0.2 x 10^-13m³The rise time is several μsec, and the bubble jet
In the case of⁶N / m ², The displacement is about 0.1 × 10
^-12m³The rise time is several μsec.

First, the electrostatic attractive force P acting on the elastic electrode is obtained. P is σ × E (11), where σ is the charge density of holes charged in the elastic electrode and E is the electric field at that point.

This electric field is formed by the electrons in the photoconductor layer electrode (A) or in the photoconductor (B). This electric field is E = (− σ) / 2ε ₁ (ε ₁ is the dielectric constant of the ink) (12) according to Gauss's theorem. Therefore, by substituting (12) into (11), P = -σ ² / 2ε 1 (13).

Therefore, if the electron charge density −σ is obtained, the electrostatic attractive force P can be calculated from the equation (13). If the photo-electrostatic ink jet head is regarded as a parallel plate capacitor, the charge amount Q of the charge is obtained by the following equation. Q = C × V (14) where C is capacitance and V is applied voltage.

The charge density is obtained by dividing the charge amount Q by the area S. σ = Q / S (15) The electric capacitance C of the formula (14) is calculated by the following formula, where the film thickness (distance between electrodes) is d when the dielectric constant of the interelectrode substance is uniform (ε, r). To be C = εr × S / d (16)

As in the present invention, the synthetic capacitance when two substances having different dielectric constants and film thicknesses are laminated is calculated by the following equation. C = S / (dl / εl + d2 / ε2) (17) In the case of (b) of the present invention, it can be considered that the photosensitive layer is substantially converted from the dielectric layer to the conductive layer by the exposure, so that the capacitance is (1
6) Equation can be applied.

That is, assuming that the film thickness and the dielectric constant of the ink layer and the photoconductor layer (in the dark) are d1, d2ε1, ε2, respectively, the capacitances C (A) and C (B) at (A) and (B) are obtained. And become equations (18) and (19), respectively. C (A) = S / (dl / εl + d2 / ε2) (18) C (B) = S / (dl / εl) (19)

The film thickness and relative permittivity of the ink layer and the photoconductor layer (in the dark) are 80 μm, 60 μm, 80, 12 and the area S is 1 respectively.
Assuming m ² , C (A) = 1 / (80 × 10 ^-6 /80×8.85×10 ^-12 + 60 × 10 ^-6 /12×8.85×10 ^-12 ) = 8.85 × 10 ^-12 / ((1 + 5 ^{) × 10 -6) = 1.48 ×} 10 -6 (F) = 1.48 (μF) (20) C (B) = 1 / (80 × 10 -6 /80×8.85×10 -12) = 8.85 × 10 - ⁶ = 8.85 (μF) (21)

From the equations (14), (15) and (20), the charge density σ (A) at the time of (A) is σ (A) = Q / S = C × V = 1.48 × 10 ⁻⁶ × 800 = 1.2 × 10 ^-3 (C / m ² ) (22) From (14), (15), (21), charge density σ (B) at (B)
Is calculated as σ (B) = 8.85 × 10 ⁻⁶ × 200 = 7.1 × 10 ⁻³ (C / m ² ) (23).

By substituting this value into the equation (13), (A), (B)
The electrostatic attraction P (A) and P (B) at each time are obtained. ^{P (A) = σ 2/} 2 × ε1 (24) = (1.2 × 10 -3) 2/2 × 80 × 8.85 × 10 -12 = 1.0 × 10 3 (N / m 2) P (B) = σ ^{2/2 × ε1 (25)} = (1.77 × 10 -3) 2/2 × 8.85 × 10 -12 = 1.77 × 10 5 (N / m 2)

This P (A) is less than the surface tension of water, and the ink does not come out from the orifice. On the other hand, this P
Although the value of (B) is smaller than that of the bubble jet, it is the same as that of the piezo and large enough to eject ink.

Next, the rise time is calculated. In the case of the present invention, the time until the state (A) becomes the state (B) is the rise time. This time is v, where v is the average speed of electrons generated in the vicinity of the electrodes of the photoconductor layer moving in the photoconductor layer due to light, and the time t required for the movement is d, where the thickness of the photoconductor layer is Next (2
It is given by the equation (6). t = d / v (26) The velocity v is given by the following equation (27) as the product of the mobility μ and the electric field E. v = μE (27)

The electron mobility of amorphous silicon is 1.
It is from 0 to 10 ^-2 (cm ² / V sec). Temporarily, take the middle and set it as 0.1 (cm ² / V sec). The electric field increases with the irradiation of light, and takes the minimum value, that is, the value before exposure. E (A) = 1.11 × 10 ⁷ (V / m) (formula omitted) (28) Substituting mobility and E (A) into formula (27), v = 0.1 × 10 ^-4 × 1.11 × 10 ⁷ = 1.11 × 10 ² (m / sec) (29)

Putting this into the equation (26), t = d / v = 60 × 10 ⁻⁶ /1.67×10 ² = 5.41 × 10 ⁻⁷ (sec) = 0.54 (μsec)

That is, it can be seen that a rise higher than that of the conventional method can be expected. Of course, the time constant of the electric circuit must be taken into consideration, but driving in μsec is possible.

Next, regarding the deformation amount, here, on the contrary, the necessary deformation amount is obtained and viewed. It is assumed that the volume of the ink ejected from the ink chamber due to the deformation of the elastic electrode is equal to twice the volume of the ejected ink droplet. As described above, the volume of ink droplets actually measured is ^{0.07~0.1 × 10 -12 (m 3)} , for simplicity, assuming the volume 0.1 × 10 ^-12 and (m ^3), spherical The radius of the ink droplet is 29 × 10 ^-6 (m).

For simplification, it is assumed that the elastic electrode 52 has moved over the entire surface with an effective width of 25 μm. When the average moving distance at this time is x, x = v / S = 0.1 × 10 ⁻¹² / (25 × 10 ⁻⁶ × 200 × 10 ⁻⁶ ) = 20 × 10 ⁻⁶ (m).

That is, it is sufficient to use an elastic body capable of deforming an average of 20 μm in this layout with an electrostatic attractive force of 4 × 10 ⁴ N / m ² . This is quite possible for current polymeric materials (however, reliability does not matter).

As described above, it has been clarified by simulation that the present invention is equivalent to or higher than the prior art in all three points of force, amount of displacement, and rise of force.

In the above description, it can be understood that the size of the ejected ink droplet can be changed by changing the exposure intensity or the exposure time, and various values can be obtained for one dot. However, if the ink droplet becomes smaller, the initial velocity also changes at the same time, so too small an ink droplet cannot fly. In addition, although the nozzle is used in the above-described embodiment, it is also possible to use a slit shape.

14 and 15 show an embodiment in which a conductive elastic body is provided in the ink chamber instead of the elastic body electrode, FIG. 14 is an exploded perspective view thereof, and FIG. 15 is a longitudinal sectional view. This inkjet head is also divided into an upper structure, a lower structure and a side structure, and then completed by laminating the three.

In the upper structure, prisms 61 for separating each ink chamber are arranged in parallel at a pitch of 63 μm as shown in the drawing.
On the insulating substrate 62, a common electrode 63 on which aluminum is uniformly vapor-deposited over the entire surface, or a rigid substrate 62 on which a conductive resin is coated as a common electrode 63, is adhered, and the prisms 61 are connected to each other. The common electrode 63 is provided with a conductive elastic body 64, the details of which will be described later.

As the prism 61, one having a moderately soft surface for absorbing a shock wave is preferable, and specifically, an appropriate resin is selected in consideration of oil repellency.

The lower structure is made by forming an inorganic photosensitive layer 66 on an electrode 65a made of an aluminum layer of conductive glass 65, and has the same structure as that of the embodiment described with reference to FIGS.
Uses the same material.

The side portion structure is almost the same as that of the above-described embodiment, and the side plate 67 made of a PET film having a thickness of 25-100 μm.
In addition, a hole (orifice) 67a having a diameter of about 20 μm is opened.

The ink jet head is completed by aligning the orifice 67a with the elongated ink chamber 68 formed by mounting the upper structure on the lower structure and fixing the side plate 67. Ink 69 is supplied to the ink chamber 68 from a passage 70.

Referring to FIG. 16, a method of manufacturing the five-face-free conductive elastic body 64, which is a key point of this embodiment, will be described.
Five-sided free means that the conductive elastic body 64 is one of the six front, back, left, right, top, and bottom surfaces other than the surface in close contact with the common electrode 63.
It means that the surfaces (four side surfaces and the upper surface) are exposed in the ink chamber 68 and are in a free state.

First, an aluminum layer to be the common electrode 63 is uniformly formed on the insulating substrate 62 by a conventionally known method by a vapor deposition method or the like, and the ink chamber 68 shown in FIGS. 14 and 15 is isolated thereon. The wall surface to be formed is formed by casting a Teflon-based or silicone-based resin. After adding an appropriate amount of acetylene black and a vulcanizing agent to chloroprene rubber and dispersing for a long time, it is diluted with an appropriate solvent such as toluene, THF, cyclohexane, butanol to obtain a solid content concentration of 15
A conductive rubber solvent a of 30 wt% is prepared from the above and poured on the above-mentioned substrate 62 placed on a horizontal table (Fig. 16 (a)).
).

Then, a metallic doctor blade b is squeezed to remove excess liquid (FIG. 16 (b)). Then, since the prism 61 is oil-repellent, the solution slightly separates from the prism and has a shape as shown in FIG. 16 (c). When this is heated, a conductive rubber layer c'having a thickness of about 10% and a thickness of about 20 .mu.m is obtained (FIG. 16 (d)). Repeat this process to a thickness of 100
The conductive rubber layer c of μm is completed (FIG. 16 (e)). At this time, the conductive rubber layer c is not fixed to the prism 61, and even if it is stuck, it can be easily peeled off by lightly moving it.

Next, a polyamide resin was added to methanol in an amount of 0.
Similarly, pour a 6 wt% dissolved solution d and squeeze it with a blade b (Fig. 16 (f)), and heat the insulating thin layer e to a conductive rubber c.
The conductive elastic body 64 is completed by overcoating on it (FIG. 16 (g)).

As the insulating thin layer e, it is preferable that the electric charge leaks in a proper time rather than a high resistance, and a polyamide resin having a volume resistivity of about 10 ¹⁰ Ωcm is suitable. Note that instead of the conductive rubber, an insulating rubber may be applied by the same method, and then the conductive resin and the insulating resin may be overcoated in this order.

In the illustrated embodiment, the wall separating the photosensitive layer and the elastic electrode, that is, the prism 61 has a height of 180 μm, the conductive elastic body 64 has a thickness of 100 μm, and the ink layer has a thickness of 80 μm.
m, the pitch of the orifice 67a is 63 μm, the ink chamber 68
The width (inter-wall distance) was set to 45 μm, but this is to simplify the simulation calculation described later, and this value is not the optimum value.

The ink jet printing and ink supply method of this embodiment will be described with reference to FIG. As in the case of the above-described embodiment, the process will be described qualitatively first and then quantitatively.

FIG. 17A shows the preparation stage. + 200v is applied to the conductive elastic body 64. As shown in the figure, the conductive elastic body 64 is charged with a small amount of holes and the electrode 65a is charged with the same amount of electrons. The electric field formed by the electrons of the electrode 65a acts on the holes of the conductive elastic body 64, and the conductive elastic body 64 receives a force directed inward. However, since the surface tension of the ink 69 is larger, the ink has an orifice 67a. No more jumping out.

Next, as shown in FIG. 17B, when light is exposed from the lower side of the photoconductor layer 66 through the Nesa glass 65 by the light emitter 71 composed of the LED array, holes and electrons are generated in the photoconductor layer 66. , The holes enter the nesa electrode and neutralize and disappear with the electrons there, and the electrons move at high speed in the photoconductor electrode 66.
It stops on the surface of the photoconductor electrode 66 as shown in (b). At this time, the amount of electrons and holes charged in the conductive elastic body 64 is
It will be several times that of (a). The reason is that when this head is regarded as a capacitor, the distance between the electrodes is 69
This is because the layer of (4) + photoconductor layer 66 is reduced to the ink layer 66 in (b). Each hole of the conductive elastic body, which is increased several times, for example, 6 times, receives 6 times the force of the electrons on the surface of the photosensitive layer, which is increased 6 times. 6 = 36 times the power. As a result, the ink chamber 68 is deformed so as to be compressed as shown in the figure, and as a result, the ink starts to be ejected in a columnar shape from the orifice 67a. At this time, the deformation of the conductive elastic body stops when the electrostatic attraction and the elastic force of the elastic body are balanced.

Next, in FIG. 17C, the conductive elastic body is grounded (exposure is completed before that, but the result is the same even if it is continued). At that moment, the conductive elastic body 64
Of the holes and the electrons of the photosensitive layer 66 disappear, the electrostatic attractive force applied to the conductive elastic body becomes zero, and the conductive elastic body is restored by the elastic force as shown in the figure. At this time, the ink chamber 68
, A force that draws ink from the left and right acts, the ink column of the orifice 67a is broken, and the ink droplet 69a as shown in the figure jumps out, and at the same time, new ink is replenished from the left side conduit 70.

It should be noted that the separation of the ink column is possible without grounding the elastic electrode and that the present invention can be applied to a copying machine having an analog lens optical system.
This is similar to the fourteenth embodiment.

Next, the above qualitative explanation is quantitatively reinforced. The point that it is an approximate calculation based on some assumptions, and the resulting formula and the like are the same as in the case of the previous embodiment.

Of the calculations for the embodiment shown in FIGS. 13 and 14, (11) to (29) can be applied to this embodiment as they are. Therefore, next, the amount of deformation of the conductive elastic body 64 is calculated. Generally, in the case of an elastic body, when a force acts on the length Lo before the force acts and the length extends to L, the force is directly proportional to the elongation. At this time, a force equal to the force pulling the elastic body from the outside is generated inside the elastic body. This is the stress σ
Call. A value obtained by dividing the extended length ΔL = L−Lo by the original length is called strain, and a proportional count of stress and strain is called an elastic coefficient (elastic modulus, Young's modulus) E. σ = E × ε (30)

That is, the original length Lo and the applied pressure P
If (= σ) and the elastic modulus E are known, the extended length ΔL can be calculated from the following equation. ΔL = Lo × σ / E (31)

The elastic modulus E of the softest rubber is 0.2
× 10 ⁶ N / m ² (= 1 MPa = ² Kgf / cm ² ), in the case of the present invention, the original length Lo is 100 × 10 ^-6 m and the electrostatic attractive force (= stress σ) is 1.77 as described above. × 10 ⁵ N / m ² . Put this value into equation (31) and obtain the deformation distance of the conductive elastic body as ΔL = (100 × 10 ^-6 × 3.57 × 10 ⁴ ) /0.2 × 10 ⁶ = 17.7 × 10 ^-6 (m) Was given. (In this case, if the elastic modulus increases by 2 digits, which is 2 × 10 ⁶ N / m, the elongation will increase by 2
Since it is less than μm, the characteristics of the piezo method of the present invention are diminished. Therefore, the elastic modulus is considered to be the limit here. )

By multiplying this by the deformable area S, the displacement amount v of the volume can be calculated. The distance between the prisms 61 is 45 μm, but the width of the conductive elastic body 64 is slightly narrower than this, so assuming 40 μm, v = S × x = (200 × 10 ⁻⁶ × 40 × 10 ⁻⁶ ). The displacement amount was calculated as × 17.7 × 10 ^-6 = 0.14 × 10 ^-12 (m ³ ). This value is also equivalent to the piezo and bubble jet methods.

From the above simulations, it was revealed that this embodiment is also equal to or higher than the prior art in the three points of force, amount of displacement, and rise of force. In addition, various values can be obtained for one dot as in the above-described embodiment. Further, needless to say, it is applicable not only to the nozzle but also to the slit.

[0142]

As described above, according to the present invention, the following effects can be obtained. (1) Ink particles return to neutral particles when ejected from the nozzle, and the particles do not interfere with each other, and recording with good resolution can be performed. (2) Ink particles fly by the force acting on the electrodes,
There are few restrictions on ink, water-based ink can be used,
It's safe.

(3) In the present invention, the distance between the electrodes can be made smaller than in the prior art, so that the applied voltage can be 1000 v or less. (4) The time constant of charging / discharging the electrode determines the printing speed, but since the electrode area can be made extremely small, the time constant is small and high-speed printing becomes possible.

(5) Since only the electrodes to which the signal is applied are deformed, the image blurring problem does not occur. (6) The life of the ink is extended because it is not necessary to heat the ink. (7) The amount of displacement of the elastic electrode can be changed by changing the applied voltage for recording, the amount of induced charge, and the electrostatic attraction acting on the electrode, which changes the size of ink particles in various ways. Can be made.

(8) If the elastic body 23 having a high dielectric constant is sandwiched, the ink flies by receiving a mechanical pressure, and the magnitude of the dielectric constant does not matter at all. It can also be used in any ink, including water ink. (9) Even if the configuration is such that the voltage of the same polarity is applied to the signal electrode and the counter electrode, the ink supply ability is high and the response is
Ink can be supplied by negative pressure without mechanical destruction. (10) With the structure using the photoconductor layer, the structure of the head is simple and light, and the multi-head becomes easy. Further, it can be driven by light and can be driven by a high voltage.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an inkjet nozzle according to the present invention.

FIG. 2 is a diagram showing an operation principle of a conventional electrostatic suction type nozzle.

FIG. 3 is a diagram showing an operating principle of the inkjet nozzle of FIG.

FIG. 4 is a perspective view showing a specific example of the inkjet nozzle shown in FIG.

FIG. 5 is a cross-sectional view showing a configuration of an embodiment in which an elastic body is sandwiched between both electrodes in the inkjet nozzle of the present invention.

6 is a perspective view showing a specific example of the inkjet nozzle shown in FIG.

FIG. 7 is a cross-sectional view showing the configuration of an example using an auxiliary electrode in the inkjet nozzle of the present invention.

8 (a) to 8 (d) are views for explaining the operation of the inkjet nozzle of FIG.

9 (a) to 9 (c) are diagrams showing the basic configuration and operation of a modified example of the embodiment of FIG.

FIG. 10 is a diagram for explaining the basic operation of the embodiment shown in FIG.

FIG. 11 is an exploded perspective view of an embodiment of the present invention using a photoconductor layer.

FIG. 12 is a vertical cross-sectional view of FIG.

13 (a) to 13 (c) are views for explaining the operation of the inkjet head of FIG.

FIG. 14 is an exploded perspective view of an embodiment of the present invention using a photoconductor layer and a conductive elastic body.

15 is a vertical cross-sectional view of FIG.

16 (a) to 16 (g) are diagrams illustrating a method for forming a conductive elastic body.

17 (a) to 17 (c) are views for explaining the operation of the inkjet head of FIG.

FIG. 18 is a cross-sectional view showing a configuration of a conventional electrostatic suction type nozzle.

[Explanation of symbols]

 11 Rigid body electrode 12,52 Elastic body electrode 13,25,33, Nozzle 14,26,34, Ink 15 Recording paper 21,31, Signal electrode 22,32, Counter electrode 23 High dielectric constant elastic body 35 Auxiliary electrode 52 Elastic body Electrodes 52a, 64 Conductive elastic bodies 54, 66 Photoconductor layers 53, 65 Conductive glass 53a Electrodes 55a, 67a Orifices 58, 70 Ink supply passages 59, 71 Light emitters 63 Common electrodes

Claims (20)

[Claims] 1. A rigid electrode and an elastic electrode are arranged to face each other to form a nozzle, ink having a high dielectric constant is put in the nozzle, and a voltage is applied between the rigid electrode and the elastic electrode. An electrostatic deformation type characterized in that the elastic body electrode is deformed in the direction of the rigid body electrode by an electrostatic attraction force acting between charges of different polarities induced on both electrodes, and the ink is ejected from the tip of the nozzle. Inkjet recording method. 2. The electrostatic deformation type inkjet according to claim 1, wherein a plurality of the nozzles are formed, an electric signal is independently applied to the elastic electrode, and the rigid electrode is used as a common electrode. Recording method by. 3. An electrostatic deformation type inkjet head, characterized in that a rigid electrode and an elastic electrode are arranged so as to face each other, and a nozzle is formed between both electrodes to insert ink having a high dielectric constant. 4. An elastic body having a high dielectric constant is sandwiched between a signal electrode and a counter electrode, at least one of which is formed of an elastic body,
A voltage is applied between both electrodes to deform the elastic body electrode toward the opposite electrode by an electrostatic attractive force acting between the electric charges of different polarities induced on both electrodes, and the elastic body having a high dielectric constant is obtained. A method for recording by electrostatic deformation type inkjet, characterized in that the ink in the nozzle in contact with the free interface of the ink is ejected from the nozzle. 5. A signal electrode and a counter electrode, at least one of which is formed of an elastic body, an elastic body having a high dielectric constant held between these electrodes, and a free interface between the elastic body having a high dielectric constant. An electrostatic deformation type inkjet head comprising a nozzle. 6. A nozzle having at least one formed of an elastic material between a signal electrode and a counter electrode, and a voltage of the same polarity is applied to the both electrodes to induce a charge of the same polarity on both electrodes. An electrostatic repulsive force acting between the elastic electrodes deforms the elastic electrodes outward, and the negative pressure causes ink to be filled in the nozzles, and a voltage of opposite polarity is applied to the electrodes to induce a difference between the electrodes. A recording method using an electrostatically-deformable inkjet head, characterized in that ink inside a nozzle is ejected from the nozzle by electrostatic attraction that acts between polar charges. 7. A nozzle is formed between a signal electrode, at least one of which is made of an elastic material, and a counter electrode, and an auxiliary electrode is provided outside the signal electrode and the counter electrode through a space. Electrostatic deformation type inkjet head. 8. An elastic body having a high dielectric constant is inserted in a space between the auxiliary electrode and the elastic body electrode.
The electrostatically deformable inkjet head described. 9. The electrostatic deformation type inkjet head according to claim 8, wherein the elastic body having a high dielectric constant is ink having a high dielectric constant. 10. The method according to claim 9, wherein a space between the auxiliary electrode and the elastic electrode is connected to the nozzle and an ink supply source, and a one-way valve is provided at each connection portion. Electrostatic deformation type inkjet head. 11. A chamber for containing ink having a high dielectric constant is formed between electrodes, at least one of which is made of an elastic body, and a passage for supplying ink is connected to the chamber and an orifice for ejecting ink is provided, An electro-deformable inkjet head comprising a photoconductor layer formed on at least one of the electrodes, and a light emitting body for exposing the photoconductor layer and an electric circuit for causing the light emitting body to emit light at a predetermined timing. . 12. The hole or electron mobility of the photoreceptor layer is
12. It is 0.01 cm ² / V sec or more, 11.
The electrostatically deformable inkjet head described. 13. The electrostatic deformation type inkjet head according to claim 11, wherein the electrode having the photoconductor layer is formed by supporting a layer of the photoconductor on a conductive glass. 14. The electrostatic deformation type inkjet head according to claim 11, wherein a ratio of a dielectric film thickness of the photoconductor layer and an ink layer is 2: 1 or more. 15. The elastic electrode, wherein at least one is made of an elastic material, and ink having a high dielectric constant is placed in a chamber formed between electrodes in which at least one is carrying a photosensitive layer, and a voltage is applied between both electrodes. Form a weak electric field that does not substantially deform, but that is sufficient to move the charges in the photoconductor layer in a short time, and at the same time or after that, expose the photoconductor layer with the light-emitting body. To generate photocarriers and move in the photoconductor layer to form a strong electric field, and the electric field deforms the elastic body electrode toward the interior by electrostatic attraction acting on the charges in the elastic body electrode, A recording method using an electrostatically-deformable inkjet characterized in that ink is ejected from an orifice formed in a chamber. 16. After ejecting ink from the orifice, the electrodes are further short-circuited to extinguish the electric field, and a negative pressure is generated in the chamber by the movement of the elastic electrode to return to the original state to eject the ejected liquid. 16. The recording method according to claim 15, wherein the ink is filled in the chamber at the same time as the cutting. 17. The ink is ejected from the orifice and at the same time, the ink in the chamber is caused to flow backward, the ejection liquid is cut off by a negative pressure generated by the inertial force thereof, and then both electrodes are short-circuited to eliminate the electric field. 16. The recording method using the electrostatic deformation type inkjet according to claim 15, wherein a negative pressure is generated in the room by the movement of returning to the original state to fill the ink in the room. 18. An ink chamber filled with high dielectric constant ink, a conduit for replenishing the ink chamber with ink, an orifice for ejecting ink droplets formed on the inner wall of the ink chamber, and one of the ink chambers. The conductive elastic body fixed to one inner wall, the photosensitive layer and its electrode provided on the inner wall facing the conductive elastic body, and the conductive elastic body and the electrode of the photosensitive layer at a predetermined timing. An electrostatic deformation type inkjet head comprising an electric circuit for applying a voltage, a light emitting body for exposing the photoconductor layer, and an electric circuit for making the light emitting body emit light at a predetermined timing. 19. The inner wall for fixing the conductive elastic body in the ink chamber is made of an oleophilic material, the other inner wall is made of an oil repellent material, and the conductive elastic body is made of another oil repellent inner wall. 19. The electrostatic deformation type ink jet head according to claim 18, wherein the electrostatic deformation type ink jet head is formed without being fixed to the. 20. An ink having a high dielectric constant is placed in a chamber formed between an electrode having a photosensitive layer and a conductive elastic body, and a voltage is applied between the conductive elastic body and the electrode. The conductive elastic body does not substantially expand or does not eject ink from the ink chamber even if it expands, but forms a weak electric field sufficient to move charges in the photosensitive layer in a short time. At the same time or after that, the photoconductor layer is exposed to light by a light-emitting body to generate photocarriers, which is moved in the photoconductor layer to form a strong electric field, and the strong electric field causes a charge in the conductive elastic body. Due to the electrostatic attraction that acts, the elastic body is expanded inside the ink chamber, the ink is projected from the orifice formed in the chamber, then both electrodes are short-circuited to eliminate the electric field, and the conductive elastic body is removed. The discharged ink is cut off by the negative pressure generated when returning to the state of Recording method by the electrostatic deformation inkjet characterized by refilling the ink in the ink chamber at the same time.