JPH11245404A - Apparatus for generating/flying ink drop - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably fly ink drops by irradiating light beams according to a predetermined signal. SOLUTION: An ink-jet recorder comprises a vibrating member 1 in contact with an ink 3, a vibration generation means 2 for vibrating the vibrating member 1, an electric field generation means 15 which includes a first electrode 6A, and generates a first electric field when a voltage is impressed and light beams are irradiated thereto and a second electric field smaller than the first electric field when the light beams are not irradiated, an exposure device 17 for projecting light beams to the electric field generation means 15 in accordance with an image signal, a driving circuit 13 for driving the vibration generation means 2 to bring about a capillary wave to the ink 3, and an electric field control circuit 9 for impressing a voltage to the first electrode 6A to act the electric field in a direction E in which drops 4 of ink formed according to the image signal fly. Since the light beams are projected thereby acting the electric field in the direction E in which the ink drops 4 fly, the ink drops 4 can fly stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink droplet generating and flying device, and more particularly, to an ink droplet generating and flying device for generating ink droplets and flying the generated ink droplets.

[0002]

2. Description of the Related Art A typical example of an ink droplet generation / flying system for performing printing by discharging droplets, particularly ink droplets, onto a surface to be printed is a system using a nozzle. Conventionally, the nozzle-type recording method includes an on-demand type and a continuous flow type.

The on-demand type is a system in which ink is intermittently ejected from nozzles in accordance with recording information to perform printing, and there are a piezo oscillator type and a thermal type as typical ones. The piezo vibrator type applies a pulse voltage to a piezoelectric element attached to the ink chamber to deform the piezoelectric element, thereby changing the ink liquid pressure in the ink chamber and ejecting ink droplets from the nozzles onto the recording paper. It records dots. In the thermal type, ink is heated by a heating element provided in an ink chamber, and ink droplets are ejected from nozzles by bubbles generated thereby to record dots on recording paper.

[0004] On the other hand, in the continuous flow type, ink is continuously ejected from a nozzle by applying pressure to the ink, and at the same time, a vibration is applied by a piezo vibrator or the like to form an ejected ink column into droplets. The recording is performed by selectively charging and deflecting.

In each of these systems, the ink drop diameter is mainly determined by the nozzle diameter. If the nozzle diameter is reduced, problems such as nozzle clogging due to dust and dust, nozzle clogging due to drying of the ink surface of the nozzle portion, and change in the ink ejection direction due to adhesion of ink residue to the nozzle circumferential portion occur. .

[0006] On the other hand, there have been proposed several recording systems for performing printing by ejecting ink droplets onto a printing surface without using a nozzle.

As shown in US Pat. No. 4,308,547, a method in which a concavely curved spherical piezoelectric shell is disposed in ink and a voltage is applied to the piezoelectric shell via an electrode. is there. In this method, longitudinal waves radiated into the ink from the piezoelectric shell are collected at one point on the free ink surface, and a drop is ejected from the free ink surface.

[0008] As shown in Japanese Patent Publication No. 6-45233, a spherical concave portion is provided on a substrate such as glass, which is used as an acoustic lens. There is a device that forms a vibrator made up of electrodes for applying a voltage, and arranges the vibrator in the ink.

Further, Japanese Patent Application Laid-Open No. 3-200199 discloses that
It is disclosed that a thin-plate flat phase Fresnel lens is provided on a substrate instead of a concave lens as a lens that is cheaper and can focus more sharply.

In a system in which a longitudinal wave is focused on the free surface of the ink and a drop is ejected from the free surface of the ink, the drop diameter is substantially equal to the focused diameter of the longitudinal wave, and the focused diameter d is:
Assuming that the driving frequency of the vibrator is f and the F value of the lens is F,
d to F / f. When the wavelength of the longitudinal wave propagating in the ink is λ and the propagation speed is v, there is a relation v = f · λ between these and the driving frequency f of the vibrator.

Therefore, for example, in a case where a very small ink droplet having a drop diameter (converging diameter) d of about 15 μm is to be ejected, if the F value of the lens is 1, the conventional low-viscosity aqueous ink Since the propagation velocity v of the longitudinal wave is approximately 1500 m / sec, the driving frequency f of the vibrator must be set to a very high frequency such as about 100 MHz. Since it is practically difficult to make the F-number of the lens extremely small due to various problems, an attempt to make the drop diameter d smaller generally requires driving the vibrator at a higher frequency.

As described above, since a plurality of vibrators must be driven at a high frequency of about 100 MHz, there is a cost problem that driving means is generally expensive, and ink viscosity changes due to heat generation due to absorption. This causes a serious problem that the drop diameter may fluctuate or the ink itself may be dried or solidified in the recording element and the ink cannot be ejected.

As a prior art other than the above, Japanese Patent Laid-Open Publication No.
No. 40070 discloses a new on-demand type recording method. This is to resonate the beam of the cantilever structure by bending vibration, generate a sufficient amplitude at the end of the beam, and fly the ink, as in the present invention,
It has the same features as the present invention such that ink can be ejected at a relatively low excitation frequency and low voltage, but uses the principle that ink droplets are formed through nozzles provided at the beam tip, As with the various recording methods of the nozzle type described above, the drop diameter is determined by the nozzle diameter, and when the nozzle diameter is reduced, there is a problem that the ink ejection direction changes due to nozzle clogging and adhesion of ink residue to the nozzle circumference. Have. Japanese Patent Application Laid-Open No. 6-340070 proposes a method for reducing the possibility of nozzle clogging as compared with the conventional method. However, as the drop diameter is determined by the nozzle diameter, it cannot be a fundamental solution.

As another prior art, Japanese Patent Application Laid-Open No. 3-154665, which is not an ink jet recording system, but is technically similar in that vibration energy is applied to atomize a liquid will be described. This is proposed as an atomization device, which consists of a vibrator including a piezoelectric ceramic, and a vibrating part that is fixed to the vibrator and that bends and vibrates in the form of a cantilever. In this case, mist-like droplets are generated by ultrasonic radiation. According to this device, it is possible to generate a small-diameter drop without using a nozzle, but a large number of drops are generated in a state that is not temporally and spatially controlled. It cannot be a recording device.

In the above-mentioned prior art, no consideration is given to flying ink droplets stably.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described circumstances, and has as its object to provide an ink droplet generation and flying device capable of stably flying ink droplets.

[0017]

In order to achieve the above object, the present invention provides a vibrating member which comes into contact with ink, vibrating means for vibrating the vibrating member, a vibrating member which is applied when a voltage is applied and a light beam is irradiated. An electric field generating means for generating a first electric field having a magnitude corresponding to the applied voltage and producing a second electric field having a magnitude smaller than the first electric field when the light beam is not irradiated; Irradiating means for irradiating the electric field generating means with a light beam, and controlling the vibrating means so that a capillary wave is generated in the ink, and an electric field is generated in a direction in which the ink droplets formed into droplets fly in response to a predetermined signal. Control means for controlling the irradiation of the light beam by the irradiation means so as to operate.

That is, the vibration member comes into contact with the ink. The vibration means vibrates the vibration member. Here, the electric field generating means generates a first electric field having a magnitude corresponding to the applied voltage when the voltage is applied and the light beam is irradiated. In addition, the electric field generating means, when not irradiated with the light beam,
Even if a voltage for generating the electric field is applied, a second electric field (including a case where the magnitude is 0) smaller than the first electric field is generated.

The irradiating means irradiates the electric field generating means with a light beam in response to a predetermined signal. As a result, the electric field generating means is in a state capable of generating the first electric field having a magnitude corresponding to the applied voltage.

The control means controls the oscillating means so that a capillary wave is generated in the ink, and controls the irradiating means so that an electric field acts in a direction in which the dropletized ink droplet flies in response to a predetermined signal. Controls light beam irradiation.

As described above, by irradiating a light beam corresponding to a predetermined signal, the electric field generating means is brought into a state capable of generating a first electric field having a magnitude corresponding to the applied voltage,
Since the vibrating member is vibrated so that a capillary wave is generated in the ink, and the irradiation of the light beam of the irradiation unit is controlled so that an electric field acts in a direction in which the ink droplets formed into droplets fly in response to a predetermined signal, At least the flying of the ink droplets is assisted by the action of the electric field. Therefore, the ink droplet can fly stably.

Here, the control means may control as follows in a state where the electric field generation means can generate the first electric field.

That is, the control means controls the vibrating means so that a capillary wave is generated in the ink and the ink in which the capillary wave is generated is formed into an ink droplet in response to a predetermined signal and flies. The irradiation of the light beam by the irradiation means may be controlled so that the electric field acts in the direction in which the light beam travels. In this case, the electric field has a role of assisting the flight of the ink droplet. Further, the control means may control the vibration means so that a capillary wave is generated in the ink, and may control the irradiation of the light beam of the irradiation means so as to fly into an ink droplet corresponding to a predetermined signal. In this case, the electric field has a role of generating the ink droplet and assisting the flight of the ink droplet. Further, the control means controls the vibrating means so that a capillary wave is generated in the ink, and controls the irradiation of the light beam of the vibrating means and the irradiating means so as to form an ink droplet and fly in response to a predetermined signal, and to control the vibration. The irradiation of the light beam by the irradiation means may be controlled so that the electric field acts in the direction in which the ink droplet flies. In this case, the electric field has a role of assisting generation and flight of the ink droplet.

In the present invention, the vibrating member is a conductor, and the electric field generating means is a working electrode located at a position separated from the vibrating member and permeable to a light beam, and a light transmitting through the working electrode. A photoconductive layer which receives the beam irradiation and reduces the resistance by the irradiation is sequentially laminated in the light beam irradiation direction, and the control means may apply a voltage to the vibration member and the working electrode. .

As described above, since the vibrating member is a conductor, and a voltage is applied to the vibrating member and the working electrode, an electric field can be generated without any additional electrodes. Therefore, the configuration can be simplified.

In the present invention, the vibrating member is a conductor, and the vibrating means is a telescopic member fixed to the vibrating member and expandable and contractable according to a voltage application state, and a vibrating member for applying a voltage to the telescopic member. And the control unit may apply a voltage to the vibration member and the vibration electrode when controlling the vibration unit.

As described above, since the vibrating member is a conductor and a voltage is applied to the vibrating member and the vibrating electrode when controlling the vibrating means, the vibrating member and the vibrating electrode can be provided without any additional electrodes. The voltage can be generated during this period, and the vibration member can be vibrated by the expansion and contraction of the expansion and contraction member. Therefore, the configuration can be simplified.

By the way, the vibrating member is made of a conductor, and the electric field generating means is arranged at a position separated from the vibrating member and irradiates the working electrode which is transparent to the light beam and the light beam transmitted through the working electrode. A photoconductive layer, which receives and reduces the resistance by the irradiation, is formed by sequentially laminating in the irradiation direction of the light beam, and a vibrating means is fixed to the vibrating member and expandable and contractable according to a voltage application state. And a vibrating electrode for applying a voltage to the telescopic member, and the control means applies a voltage to the vibrating member, the working electrode, and the vibrating electrode. The applied voltage and the voltage applied to the vibrating member and the vibrating electrode interfere with each other, so that an ink droplet cannot be generated properly. Therefore, in the present invention, the vibration member is maintained at a constant potential.

As described above, if the vibration member is maintained at a constant potential, the interference between the voltage applied to the vibration member and the working electrode and the voltage applied to the vibration member and the vibration electrode can be prevented. Thus, the ink droplet can be generated properly.

[0030]

Embodiments of the present invention will be described below in detail with reference to the drawings.

As shown in FIG. 1, an ink jet recording apparatus including an ink droplet generating and flying apparatus according to one embodiment of the present invention modulates a light beam and irradiates a photoconductive layer 16 of the electric field generating means 15 to be described later. The exposure device 17 is provided.
The exposure unit 17 corresponds to the irradiation unit of the present invention. As the exposure device 17, a semiconductor laser having an output of about several tens of milliwatts or less used in a known laser beam printer can be used. In addition, it is also possible to use an LED, an EL, a plasma light emitting cell, a combination of a liquid crystal cell and a lamp, and the like.

The electric field generating means 15 includes a vibration member 1 described later.
In the direction of irradiation of the light beam from the exposure device 17,
The transparent substrate 18, the first electrode 6 </ b> A having a light beam transmitting property, and the photoconductive layer 16 are sequentially arranged. Note that the first electrode 6A corresponds to the working electrode of the present invention.

Further, the ink jet recording apparatus includes a conductive vibrating member 1 which is spaced apart from the electric field generating means 15 via the recording medium 5 and whose longitudinal direction is arranged in a predetermined direction. It is connected to the long recording head 14 provided therein, the first electrode 6A and the vibration member 1 via signal lines 6E and 6F, respectively, and generates an electric field of a predetermined magnitude corresponding to an image signal. Thus, the electric field control circuit 9 for outputting and controlling a predetermined voltage signal is provided.

Here, the predetermined direction corresponds to the scanning direction of the recording medium 5. The length of the vibration member 1 in the longitudinal direction corresponds to the length of the recording medium 5.

The recording head 14 has an ink chamber 10 composed of an ink chamber wall 11 and a support member 12. The ink 3 is supplied to the ink chamber 10 by an ink supply unit (not shown).

The vibration member 1 is disposed in the ink chamber 10, and the vibration generation means 2 as the vibration means of the present invention is integrated (fixed), and one end is supported by the support member 12 so as to form a cantilever structure. At least the vicinity of the tip is in contact with the ink 3.

The vibration generating means 2 includes a piezoelectric member (extendable member) 8 fixed to the vibration member 1 and an electrode (not shown) for applying a voltage to the piezoelectric member 8 on the opposite side of the vibration member 1 with the piezoelectric member 8 interposed therebetween. (Vibrating electrode) 20.

A drive circuit 13 for outputting and controlling a voltage signal for exciting the vibration member 1 at a predetermined frequency in accordance with a reference clock is connected to the electrode 20 and the vibration member 1. The drive circuit 13 is connected to the electric field control circuit 9. The vibration member 1 is grounded.

The electric field control circuit 9 and the drive circuit 13 constitute the control means of the present invention. Since the voltage is applied to the vibration member 1 as described above, the vibration member 1 may be made of a conductive material such as SUS, Ni, Al, Fe,
Ti, Cr, Au, Mo, TiW, etc., or various alloys thereof can be used.

As shown in FIG. 2, the vibrating members 1 are arranged in a predetermined direction as described above, and have a plurality of strip-shaped members (vibrators) 1a each having a tapered tip (for example, an isosceles triangle). , 1b, 1c,... Are integrated on the base end side (right side).

Next, the operation of the present embodiment will be described. A computer (not shown) inputs the reference clock to the drive circuit 13 as shown in FIG.

The drive circuit 13 to which the reference clock has been input
As shown in FIG. 3D, a drive signal for generating a capillary wave (surface tension wave) in the ink 3 contacting the vibration member 1 is output to the electrode 20. That is, the drive signal has a waveform signal in which at least one waveform having one cycle determined by the reciprocal of the resonance frequency of the vibration member 1 is continuous, and is a burst wave that is applied intermittently. The burst wave is not limited to the illustrated triangular wave, but may be a rectangular wave, a sine wave, or the like. The frequency of the drive signal is a frequency at which the vibration member 1 resonates due to bending vibration. When the vibration member 1 is excited at the frequency, the tip vibrates with a large amplitude.

As a result, the ink 3 coming into contact with the vibration member 1 is subjected to the action of vibration to generate a capillary wave 22 on the surface of the vibration member 1 and also covers the tip of the vibration member 1 as shown in FIG. The distance (the thickness of the ink shown) L between the surface of the ink and the surface of the vibration member 1 can be set to several μm to several hundred μm.

Since the distal end portion is tapered, the bending stiffness (moment of inertia) of the vibrating member 1 can be reduced toward the distal end portion to increase the amplitude of the bending vibration of the distal end portion. In addition, the region where the capillary wave is generated can be limited, and the effect of preventing a plurality of ink droplets from flying is great.

In this embodiment, the vibration member 1
The flight point 50 is set at a predetermined position by adjusting the physical properties such as the material and the shape. The predetermined position is a position where a capillary wave with two wave fronts is formed in the ink 3 on a plane perpendicular to the bending vibration direction of the vibration member 1. That is, as shown in FIG. 4A, the predetermined position is a position where the width W of the surface in the direction orthogonal to the vibration direction is approximately 2λ with respect to λ given by the following equation 1. The width W is 1.2λ
It is preferable that the thickness be in the range of λ2.4λ (the length at which two capillary waves are formed).

Λ = {8πσ / (ρfe ² )} ^1/3 × 10 ⁴ (μm) Expression 1 where σ is the ink surface tension (mN / m) and ρ is the ink density (g / cm). ³ ) fe is the excitation frequency (Hz) The above equation 1 is described as a formula for giving the wavelength of the capillary wave to a general reference person, for example, Chika Chiba, “Ultrasonic Spraying” (Sankaido), Chapter 7, Section 2. Is what is being done.

When the vibrating member 1 is excited as described above, the ink at the flying point 50 generates a capillary wave with two wave fronts 24 at time t as shown in FIG. At the time t + Δt of FIG.
As shown in (1), a capillary wave of one minute wave front 24 serving as a source of the ink droplet 4 is generated, and this is repeated.

On the other hand, the electric field control circuit 9
A voltage signal (output signal: V volt) in the range of 0 [V] is output to the first electrode 6A. Therefore, as shown in FIG. 6, the first electrode 6A is held at V volts, and the vibration member 1 is held at 0 volts.

The exposure device scans the light beam in a predetermined direction. Based on the timing at which the image signal is input, the exposure device 17 outputs a driving circuit 1 as shown in FIG.
The light beam is irradiated with a delay of a predetermined time from the start of the application of the drive signal by 3. Thus, the light beam irradiates the photoconductive layer 16 via the transparent substrate 18 and the first electrode 6A.

As a result, in the photoconductive layer 16, the resistance of the region 16A irradiated with the light beam becomes sufficiently small, and as a result, the potential of the region 16A of the photoconductive layer 16 becomes V volt.

On the other hand, the region 16B not irradiated with the light beam
Since the photoconductive layer 16 has a sufficiently high resistance, the region 1 of the photoconductive layer 16 is formed by the voltage dividing effect of the capacitance impedance of each layer.
The potential of 6B becomes V '(<V) volts.

Accordingly, an electric field having a magnitude of E is generated between the region 16A and the vibrating body 1b, and
An electric field having a magnitude of E ′ (<E) is generated in each of the areas a and c.

The wave front 24 of the ink 3 in which a capillary wave is generated at the flight point 50 of the vibrating member 1 (vibrating bodies 1a, 1b, 1c.
, And the wave front 24 is torn off to generate an ink droplet 4. On the other hand, even when an electric field having a size of E '(<E) acts, the ink droplet 4 is not generated. As described above, in the present embodiment, the ink droplet 4 is generated by the action of the electric field having the size E, and the size is E ′ (<
The intensity of the electric field and the capillary wave forming conditions are adjusted so that the ink droplet 4 is not generated even when the electric field E) acts.

Accordingly, an electric field having a magnitude of E acts to generate an ink droplet 4, and the direction of the electric field is the flying direction of the ink droplet 4, so that the generated ink droplet 4 is directed toward the first electrode 6A. And arrives (prints) on the recording medium 5. Note that the ink droplet 4 does not reach the recording medium 5 corresponding to the area where the electric field having the size of E 'has acted.

The flight point 50 in FIG. 4A is shown for the above description, and does not need to be particularly provided on the surface of the vibration member 1. The flight point depends on the material and shape size of the vibration member 1 and the excitation conditions of the vibration generation means 2 and the like.
Is designed to be fixed at a predetermined point at the tip of the. However, it is effective to apply a surface treatment or the like for adjusting the wettability to the ink droplet discharge point for the purpose of preventing the ink droplet discharge point from fluctuating even if various conditions slightly change.

By the way, as described above, the vibration member 1 is grounded and maintained at a predetermined potential (0 volt (ground potential)). When generating an electric field, the first electrode 6
When the potential of A is changed and the vibration member 1 is vibrated, the potential of the electrode 20 is changed. This is because, when the potential of the vibration member 1 is changed, this potential change
This has an effect on the voltage to be applied and the magnitude of the generated electric field. Thus, the electric field between the recording head 14 and the recording medium 18 is stably controlled by the electric field control circuit 9, and the electric field applied to the piezoelectric member 8 is stably controlled by the drive circuit 13.

In this embodiment, a voltage is applied to the first electrode 6A in accordance with the image signal, and no electric field is formed when the light beam is not irradiated (when printing is not performed). Only), an electric field is generated to generate and fly ink droplets. This is because it is more preferable in terms of energy consumption than the case where the electric field E 'is always applied and the electric field E is applied to generate and fly ink droplets when the light beam is irradiated.

The frequency at which the vibration generating means 2 is excited may be any value. However, when the vibration generating means 2 is driven at a frequency equal to or a multiple of the resonance frequency of the vibration generating means 2, vibration can be efficiently performed. Further, the number of bursts and the voltage can be appropriately set as adjustment parameters for stably forming a capillary wave.

As described above, in the present embodiment, an electric field is applied to the ink 3 forming the capillary wave on the tip surface of the vibrating member 1 to generate and fly ink droplets. The frequency can be increased, and high-speed and stable ink droplet flight is realized.

Further, in the above-described embodiment, since the vibration member is a conductor and a voltage is applied to the vibration member and the first electrode, an electric field can be generated without any additional electrodes. . Therefore, the configuration can be simplified.

Further, in the above-described embodiment, the vibration member is a conductor, and a voltage is applied to the vibration member and the electrodes constituting the vibration means. By generating a voltage between the vibrating electrodes, the vibrating member can be vibrated by the expansion and contraction of the piezoelectric element. Therefore, the configuration can be simplified.

Further, in the above-described embodiment, since the vibration member is maintained at a constant potential, the voltage applied to the vibration member and the first electrode of the electric field generating means and the voltage applied to the vibration member and the electrode of the vibration generating means are different. Interference with the applied voltage can be prevented, and ink droplets can be properly generated.

According to the above-described embodiment, fine droplets are generated without nozzles, ink is not clogged,
It is possible to realize a recording head capable of high-quality recording.

Further, since the capillary wave is used, driving at a low frequency can be performed, and the vibration for generating the capillary wave is realized in the resonance mode of the bending vibration of the cantilever beam. The tip has a sufficiently large amplitude and can be driven with low power. Further, since a piezoelectric material having high energy efficiency can be adopted, it can be driven with low power. Accordingly, the ink has good energy efficiency, and the range of physical properties of the ink that can be used in the present invention is widened.

Further, since the flight of ink droplets is controlled by the electric field between the recording head and the recording medium, the use of vibration energy is sufficient if a stable capillary wave is formed, and it is not necessary to apply excessively. The problem of heat generation, which is a conventional problem of the vibration energy utilizing system, does not occur.

Further, since the scanning and the combination with the light beam can be performed, the light beam can be irradiated at a high speed and with high uniformity, and high-speed and high-quality printing can be performed.

The photoconductive layer 16 is made of a material exhibiting photoconductivity with respect to at least the light beam irradiated by the exposure device, and the volume resistivity of the irradiated surface is three times or more that of the non-irradiated surface due to the light irradiation. To provide conductivity,
A material that gives 20 times or more conductivity is more preferable. Specifically, crystalline silicon, other crystalline silicon, microcrystalline silicon, non-crystalline silicon, and those obtained by mixing or adding or doping other substances of these plural materials, Se, CdS, CdSe, HgCdTe, PbSnTe
Alternatively, Ge or Si doped with Au, Hg, Cu, Zn, or the like may be used.

Further, in the above-described embodiment, the electric field generating means is formed by the transparent substrate 18 and the first electrode 6 having light beam transparency.
A and the photoconductive layer 16 are arranged in order,
The present invention is not limited to this, and may be configured as follows.

An intermediate layer and a surface layer can be appropriately provided between the layers of the electric field generating means 15 in order to improve the electrical characteristics or mechanical strength, or by selectively patterning each layer, for the convenience of device fabrication. .

Here, the photoconductive layer 16 is exposed on the surface.
Then, wear due to contact / sliding with the recording medium 5 becomes a problem.
Sometimes. In addition, moisture in the air is contained in the photoconductive layer 16.
The penetrating photoconductive properties may be degraded. Therefore,
Providing a protective layer on the surface of the photoconductive layer 16 is a means of generating an electric field.
It is important to maintain the performance of step 15 stable for a long time.
You. The protective layer has excellent abrasion and water resistance,
Or high-resistance various resin materials and ceramic materials
Is available. Further, the protective layer is provided with anisotropic conductive performance.
It is also effective. Set the protective layer to the direction of the light beam
Conductivity is higher than the conductivity in the direction perpendicular to the light beam irradiation direction.
To reduce the resolution.
It is possible to thicken the protective layer thin film without
It is easy to achieve both abrasion resistance, water resistance and image quality. Anisotropic conductivity
Protective film is made of various conductive or insulating materials.
Conductive filler or conductive material is arranged to show anisotropic conductivity
It can be realized by blending. As an insulating substrate,
AlN, SiN_Four, Al_TwoO _Three, MgO, VO_Two, Si
O_Two, ZrO_Four, MO_Two, Bi_TwoO_Three, TiO_Two, Mo
O_Two, WO_Two, NbO_Two, ReO_ThreeCeramic materials such as
Material, polyimide resin, polyaramid resin, polyester
Resin, polyimide amide resin, polysulfone resin, poly
Phenylene oxide resin, poly-P-xylylene resin, etc.
Alternatively, there is a resin material containing such a dielectric. Conductive foil
C, Ni, Au, Ag, F
e, Al, Ti, Pd, Ta, Cu, Co, Cr, P
Inorganic materials such as t, Mo, Ru, W, and In can be applied.
is there.

As the transparent substrate 18, a transparent plastic film other than a glass substrate can be used. However, it is necessary to select a substrate that meets the conditions for forming the first electrode 6, the photoconductive layer 16, and the anisotropic conductive layer if necessary.

[0072] Incidentally, the vibration member 1 can be converted into bending vibration of the vibration of the vibration generating means 2, so may be a member capable of generating sufficient amplitude to the capillary waves generated near the tip, SiO _2, SiON , SiN, AlN, Al ₂
Various inorganic materials such as O _3, and various resins such as a cyanoacrylate resin, an epoxy resin, and a fluorine resin can also be used. When a material that is not a good conductor is used, it is necessary to separately provide an electrode that supports the piezoelectric member 8.

When a material of a poor conductor is used for the vibration member 1, it is necessary to provide a second electrode separately as in the case of the above-mentioned vibration generating means. In such a case, the electric field generated by the first electrode 6 </ b> A and the second electrode 7 may be arranged so as to effectively act on the capillary wave at the distal end of the vibration member 1.

The vibration generating means 2 may generate vibration in accordance with a voltage signal input from the drive circuit 13 in addition to the piezoelectric member, and may be a magnetostrictive material, a mechanical actuator, or an actuator using electrostatic force. Although piezoelectric materials are widely used as functional materials for ink jet printers and advanced manufacturing techniques have been established, piezoelectric materials are optimal. Quartz, PZ as piezoelectric material
T, barium titanate BaTiO ₃ , lead niobate PbN
b ₂ O ₆ , bismuth germanate Bi ₁₂ GeO ₂₀ , lithium niobate LiNbO ₃ , lithium tantalate LiT
polycrystalline or single crystal such as aO ₃ , or ZnO or Al
It is possible to use a piezoelectric thin film such as N, a piezoelectric polymer such as polyurea, PVDF (polyvinylidene fluoride) or a copolymer of PVDF, or a composite of an inorganic piezoelectric substance such as PZT and a piezoelectric polymer. it can.

For the purpose of protecting the vibration member 1 from alteration, corrosion, adhesion of foreign matter, etc., it is effective to coat the surface with a metal such as gold, platinum, palladium, rhodium and a thin film such as PTFE.

The vibration member 1 is not limited to a plate having a uniform thickness.
Various shapes such as a rod shape and a weight shape can be designed. However, in terms of the stability of vibration, the stability of the drop flying direction, and the stability of ink retention, it is preferable to design at least the vicinity 4 of the leading end into a thin plate shape. .

Further, the vibrating member 1 does not necessarily need to be formed of a single material and a single member.
It may be a composite structure composed of members. It is also effective to use a gradient material whose physical properties (density, Young's modulus, etc.) gradually change depending on the position of the member, as a method for achieving a plurality of different performances at the same time.

The vibrating member 1n of the vibrating member 1 has an isosceles triangular shape, but the present invention is not limited to this.
As shown in FIG. 7A, a vibrating body having the above-described width W, and as shown in FIG. As shown in (C), a vibrating body having a portion having the above-mentioned width W and having a shape gradually narrowing toward the tip end may be adopted.

As shown in FIGS. 8A to 8D, a vibrating body of a predetermined shape (circle or rectangle) having the above-mentioned width W at the tapered tip may be employed. .

Although the plurality of vibrators are integrated on the base end side, the present invention is not limited to this, and may have a separate and independent configuration. [Embodiment 1] Next, a first embodiment of the present invention will be described. The basic configuration is the same as FIG. The elastic member 1 is obtained by processing a 5 μm-thick stainless film with high precision using an excimer laser. The vibration generating means 2 includes a thin-film piezoelectric member 8 made of lead zirconate titanate (PZT) and an electrode for applying a voltage to the thin-film piezoelectric member 8, and the piezoelectric member 8 is sandwiched between the electrodes. The vibration generating means 2 is integrated with the vibration member 1 and is supported by a support member 12 of the recording head. P
The thin-film piezoelectric member 8 made of ZT has been subjected to a polarization treatment, and generates a distortion when a voltage is applied between the electrodes, and vibrates when an alternating voltage is applied. In this embodiment, the vibration member 1 is configured to serve as one of the second electrode and the electrode of the vibration generating means 2. A piezoelectric member 8 made of PZT was formed on the surface of the vibrating member 1 on the ink chamber side, and an electrode for exciting the piezoelectric member 8 was formed. The second electrode 7 is maintained at the ground potential to form a stable electric field and apply a stable excitation signal to the piezoelectric member 8.

The electric field control circuit 9 includes the first electrode 6 and the vibration member 1
The signal applied during is DC voltage = 1000 volts.

The exposure device 17 is a laser beam scanning means provided with a semiconductor laser light source having an oscillation wavelength of 780 nm and an output of 30 mW, a polygon mirror scanning system, and an optical system such as an f · θ lens. Exposure.

When the surface potential was confirmed off-line, the surface potential of the photoconductive layer 16 on the side in contact with the recording medium 5 immediately after the laser beam irradiation was 985 port. On the other hand, the surface potential at the same position without laser beam irradiation was 730 volts. A printing test was performed in this state.

As the ink 3, a commercially available water-based ink was used.
Surface tension = 35 mN / m, density = 1.10 g / cm ³ ,
The viscosity is 2.0 mPa · S.

The signal applied to the vibration generating means 2 has a frequency of 350 kHz, the number of bursts = 12, and an excitation voltage = 12 V
pp (maximum / minimum amplitude), waveform = sine wave.

Stable flying of the ink droplet 4 was realized only from the laser beam irradiation position, and a high quality print sample was obtained. The diameter of the flying ink droplet 4 was 19 μm, and the average dot diameter on the recording medium 5 was 38 μm. [Embodiment 2] FIG. 9 shows the configuration of a second embodiment of the present invention. The vibration member 1 was formed of a polyimide film having a thickness of 12 μm, and a metal thin film was formed by vapor deposition on the surface facing the recording medium 5 to form a second electrode 7. In the vibration generating means 2, an electrode 2E1 was formed on the surface of the electric charging member 1 on the ink chamber side, a piezoelectric member 8 made of PZT was formed, and further an electrode 2E2 was formed. The second electrode 7 is maintained at the ground potential to form a stable electric field and apply a stable excitation signal to the piezoelectric member 8.

The electric field control circuit 9 includes the first electrode 6 and the second electrode 7
The signal applied during is DC voltage = 500 volts.

The exposure apparatus 17 is a laser beam scanning means having an oscillation wavelength of 780 nm, an output of 30 mW, a semiconductor laser light source, a polygon mirror scanning system, and an optical system such as an f · θ lens. And a printing test was performed.

As the ink 3, a commercially available water-based ink was used.
Surface tension = 30 mN / m, density = 1.15 g / cm ³ ,
The viscosity is 2.2 mPa · S.

The signal applied to the vibration generating means 2 has a frequency of 192 kHz, a burst number of 7, an excitation voltage of 8 Vp-
p (maximum / lowest amplitude), waveform = sine wave.

As a result, stable flight of the ink droplet 4 was realized only from the laser beam irradiation position, and a high quality print sample was obtained. The diameter of the flying ink droplet 4 is 25 μm,
The average dot diameter on the recording medium 5 was 46 μm.

[0092]

As described above, according to the present invention, by irradiating a light beam corresponding to a predetermined signal, the electric field generating means can generate the first electric field having a magnitude corresponding to the applied voltage. And oscillate the vibrating member so that capillary waves are generated in the ink, and irradiate the light beam of the irradiating means so that an electric field acts in the direction in which the ink droplets formed into droplets fly in response to a predetermined signal. Since the control is performed, at least the flying of the ink droplet can be assisted, and the ink droplet can be stably fly.

According to the present invention, since a voltage is applied to the vibrating member and the working electrode, an electric field can be generated without any additional electrodes, and the structure can be simplified.

In the present invention, a voltage is applied to the vibrating member and the vibrating electrode, so that a voltage is generated between the vibrating member and the vibrating electrode and the vibrating member is expanded and contracted by the expansion and contraction of the expandable member without any additional electrodes. Vibration can be achieved, and the configuration can be simplified.

In the present invention, since the vibration member is maintained at a constant potential, it is possible to prevent interference between the voltage applied to the vibration member and the working electrode and the voltage applied to the vibration member and the vibration electrode. This has the effect that ink droplets can be generated properly.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an ink jet recording apparatus according to an embodiment.

FIG. 2 is a diagram showing a shape of a vibration member.

FIG. 3 is a timing chart of the embodiment.

4A is a diagram illustrating a position of a flying point at a tip end portion of a vibration member, and FIG. 4B is a diagram illustrating a state at a predetermined time in a cross section taken along line X1-X2 in FIG. And
FIG. 4C is a cross-sectional view taken along the line X1-X2 in FIG.
FIG. 9 is a diagram illustrating a state when a predetermined time has further elapsed from (B).

FIG. 5 is a diagram illustrating a state when an ink droplet is generated and flies.

FIG. 6 is a diagram showing the magnitude of an electric field in a region irradiated with a light beam and a region not irradiated with the light beam.

FIG. 7 is a diagram showing a modified example of the vibrating body.

FIG. 8 is a view showing still another modified example of the vibrating body.

FIG. 9 is a schematic diagram of an ink jet recording apparatus according to a second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vibration member 2 Vibration generation means (vibration means) 6A 1st electrode (working electrode) 16 Photoconductive layer 11 Piezoelectric member (expandable member) 15 Electric field generation means 17 Exposure device (irradiation means) 20 Electrode (vibration electrode) 60 Electric field control Circuit (control means) 50 Drive circuit (control means)

Claims (4)

[Claims] A vibrating member that comes into contact with ink; vibrating means for vibrating the vibrating member; and a first electric field having a magnitude corresponding to the applied voltage when a voltage is applied and a light beam is applied. A second electric field which is smaller than the first electric field when generated and not irradiated with a light beam.
An electric field generating means for generating an electric field of; an irradiating means for irradiating the electric field generating means with a light beam in response to a predetermined signal; and controlling the oscillating means so that a capillary wave is generated in the ink; Control means for controlling the irradiation of the light beam of the irradiation means so that an electric field acts in a direction in which the ink droplets formed in accordance with (1) fly. 2. The vibrating member is a conductor, and the electric field generating means is located at a position separated from the vibrating member and has a working electrode permeable to a light beam and a light beam transmitted through the working electrode. And a photoconductive layer of which resistance is reduced by the irradiation is sequentially laminated in the irradiation direction of the light beam, and the control means applies a voltage to the vibration member and the working electrode. The flying device for producing ink droplets according to claim 1, wherein: 3. The vibrating member is a conductor, the vibrating means is fixed to the vibrating member and expands and contracts in accordance with a voltage application state, and a vibrating electrode for applying a voltage to the expandable member. The ink droplet generation and flying device according to claim 1, wherein the control unit applies a voltage to the vibration member and the vibration electrode. 4. The vibrating member is a conductor, and the electric field generating means is located at a position separated from the vibrating member and has a working electrode permeable to a light beam and a light beam transmitted through the working electrode. And a photoconductive layer whose resistance is reduced by the irradiation is sequentially laminated in the irradiation direction of the light beam. The vibrating means is fixed to the vibrating member and expands and contracts according to a voltage application state. And a vibrating electrode for applying a voltage to the telescopic member. The control means applies a voltage to the vibrating member, the working electrode, and the vibrating electrode, and The ink droplet generation and flying device according to claim 1, wherein the member is maintained at a constant potential.