JPH11235822A - Recording head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a recording head capable of recording a high resolution image by ejecting small ink drops without using a nozzle. SOLUTION: When an input signal from a signal generating means 32 is inputted to a vibration generating means 24 in accordance with an image signal, a piezoelectric vibration section 34A of an elastic section 34 is vibrated, thereby causing bending vibration of an elastic section 34B. As a result, a portion in the vicinity of a tip section 34C of the elastic section 34B is subjected to the bending vibration having the large amplitude to generate a capillary wave so that small ink drops are continuously ejected one by one. As the elastic section 34 is equipped with the piezoelectric vibration section 34A as a piezoelectric vibrator element and the elastic section 34B as an elastic member and an adhesive face or another member (such as an adhesive) is not provided between the piezoelectric vibration section 34A and elastic section 34B, the vibration of the piezoelectric vibration section 34A is not attenuated so that it is directly transferred to the elastic section 34B.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording head for recording an image by flying ink droplets and landing them at a predetermined position on a recording medium.

[0002]

2. Description of the Related Art A typical example of an ink jet recording system for performing printing by ejecting droplets, particularly ink droplets, onto a surface to be printed is a system using a nozzle. A demand type and a continuous flow type are known.

[0003] The on-demand type is a system in which ink is intermittently ejected from nozzles in accordance with recording information to perform printing, and typical types include a piezo oscillator type and a thermal type. 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 nozzles to form dots on recording paper. It is to be recorded. 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.

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

In each of these methods, the diameter of the ink droplet is mainly determined by the diameter of the nozzle. When the nozzle diameter is reduced, nozzle clogging due to dust or dust,
There is a problem that the ink discharge direction changes due to the adhesion of the ink residue to the nozzle circumference.

[0006] On the other hand, there have been proposed some recording systems for performing printing by ejecting ink droplets onto a surface to be printed without using a nozzle. For example, US Pat. No. 4,308,547
As shown in the specification, there is a recording method in which a spherically curved piezoelectric body shell that is concavely curved is disposed in ink, and a voltage is applied to the piezoelectric body shell through an electrode. In this method, longitudinal waves radiated into the ink from the piezoelectric shell are collected at one point on the free ink surface, and ink droplets are ejected from the free ink surface.

Further, as disclosed 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, and a piezoelectric body and a voltage There is also a recording method in which a vibrator composed of electrodes for applying a voltage is formed and the vibrator is arranged in ink.

Further, Japanese Patent Application Laid-Open No. 3-200199 discloses a recording method in which a thin-film flat plate-shaped phase Fresnel lens is provided on a substrate instead of a concave lens as an inexpensive and sharper focusing lens. It is shown.

In the above-described system in which longitudinal waves are focused on the free ink surface and ink droplets are ejected from the free ink surface, the diameter of the ink drops is substantially equal to the focused diameter of the longitudinal waves, and the focused diameter d is If the drive frequency of f 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 diameter (converging diameter) d of about 15 μm is to be ejected, if the F value of the lens is set to 1, the conventional low-viscosity, aqueous Since the propagation velocity v of the longitudinal wave in the ink 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 value of the lens extremely small due to various problems, the diameter d of the ink droplet
If one wishes to reduce, the vibrator must generally be driven at a higher frequency.

As described above, in the method in which longitudinal waves are focused on the free ink surface and ink droplets are ejected from the free ink surface, a plurality of vibrators must be driven at a high frequency of about 100 MHz. Causes the cost problem that the ink becomes expensive, and the heat generated by the absorption changes the ink viscosity, causing the diameter of the ink droplet to fluctuate, or causing the ink itself to dry or solidify in the recording element, making it impossible to discharge the ink. Can cause serious problems.

As a prior art other than the above, Japanese Patent Application Laid-Open No.
Japanese Patent No. 40070 discloses a new on-demand type recording method. This is to resonate a beam of cantilever structure by bending vibration, generate sufficient amplitude at the tip of the beam and fly ink, and it is possible to eject ink at a relatively low excitation frequency and low voltage. This is a recording method that has characteristics. However, this recording method uses a mechanism for forming ink droplets via a nozzle provided at the tip of the beam, and the diameter of the ink droplet is determined by the nozzle diameter, as in the various nozzle-type recording methods described above. Therefore, 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 circumferential portion. Japanese Unexamined Patent Publication No. 6-3400
The technique disclosed in Japanese Patent No. 70 is one of the technical problems to be solved to reduce the possibility of nozzle clogging as compared with the conventional method, however, the diameter of the ink droplet is determined by the nozzle diameter. It cannot be a fundamental solution.

As yet another prior art, a method of forming fine liquid by applying vibration energy, which is not an ink jet recording method, is disclosed in Japanese Patent Application Laid-Open No. 3-154665.
No., published in Japanese Patent Application Publication No. This method is intended to be applied to an atomizing device, and includes a vibrator including a piezoelectric ceramic,
The vibrating part is fixed to the vibrator and bends and vibrates in the form of a cantilever. A part of the vibrating part is immersed in a liquid, and mist-like liquid droplets are generated by radiation of ultrasonic waves. However, with the technology used in this atomizing device, although it is possible to generate minute diameter ink droplets without using a nozzle,
Since a large number of ink droplets that are not temporally and spatially controlled are generated, the method cannot be applied to an ink jet recording apparatus that needs to accurately land ink droplets at a predetermined position on a recording medium.

As described above, in recent years, high-resolution image recording on a recording medium has been increasingly demanded. However, even if any conventional recording method or a technique in another field such as an atomizing apparatus is used, these demands can be met. Difficult to respond to.

[0015]

SUMMARY OF THE INVENTION In view of the above, it is an object of the present invention to provide a recording head capable of discharging fine ink droplets without using a nozzle and capable of recording a high-resolution image.

[0016]

According to the first aspect of the present invention, there is provided an ink chamber in which ink is stored, and a piezoelectric vibrating portion disposed in the ink chamber and partially vibrating when an alternating electric field is applied. Another part is an elastic part that bends and vibrates in accordance with the vibration of the piezoelectric vibrating part and that causes the ink thin film to fly from the ink thin film formed on the surface by the bending vibration and adhere the ink droplet to the recording medium. And an exciting unit that excites the piezoelectric vibrating unit according to an input signal input corresponding to an image signal.

Therefore, when the input signal corresponding to the image signal is inputted, the excitation means vibrates the piezoelectric vibrating portion of the vibrating member. The vibrating member is arranged in the ink chamber, and when the piezoelectric vibrating portion is excited by the exciting means, the elastic portion bends and vibrates, causing ink droplets to fly from the ink thin film formed on the surface and causing the ink droplets to fall on the recording medium. Attach.

As described above, since fine ink droplets can be ejected without using a nozzle, an ink ejection failure due to nozzle clogging and a change in the ink ejection direction due to adhesion of ink to the periphery of the nozzle may occur. And a high-resolution image can always be obtained accurately.

A part of the vibration member is a piezoelectric vibration part, and another part is an elastic part. When the piezoelectric vibrating portion and the elastic portion are configured by different members, an adhesive surface or another member is interposed in a vibration transmission path between the piezoelectric vibrating portion and the elastic portion. Since there is no bonding surface or another member, the vibration of the piezoelectric vibrating portion is transmitted to the elastic portion with high vibration efficiency without being attenuated. Also, there is no deterioration of the joint.

According to a second aspect of the present invention, in the first aspect, the exciting means is an electrode for applying an alternating electric field corresponding to an image signal to the piezoelectric vibrating section.

That is, the piezoelectric vibrating section can be vibrated with a simple structure using only the electrodes as the excitation means.

According to a third aspect of the present invention, in the second aspect of the present invention, a plurality of the vibrating members are arranged in the ink chamber, and a plurality of the vibrating members are integrally formed. And

That is, since the plurality of vibration members are integrally formed, the number of parts can be reduced, and the accuracy of the mounting position of the vibration members can be increased.

[0024]

1 and 2 show a first embodiment of the present invention.
1 shows a schematic configuration of a recording head 10 according to the embodiment.

The recording head 10 has a substrate 12 formed in the shape of a long flat plate, and a width direction of the substrate 12 (the horizontal direction in FIG. 1).
An ink chamber 18 surrounded by a pair of ink chamber walls 14 erected vertically from near both ends. A predetermined amount of ink 20 is stored in the ink chamber 18.

An ink supply passage 22 is formed at the lower end of one of the ink chamber walls 14 (the left side in FIGS. 1 and 2), and the ink is supplied from an ink tank (not shown) into the ink chamber 18. 20 can be supplied.

On the upper surface of the substrate 12, a plurality of vibration generating means 24 are fixed at predetermined intervals along the longitudinal direction of the substrate 12. As shown in detail in FIG. 1, the vibration generating means 24 includes a vibration member 34 formed in a substantially L-shape in a front view.
A piezoelectric vibrating portion 34A, and electrodes 28 attached to the upper and lower surfaces of the horizontal portion of the vibrating member 34 by thermocompression bonding or the like,
30. Signal generating means 32 is connected to the electrodes 28 and 30. When an alternating voltage corresponding to an image signal is input from the signal generating means 32, an alternating electric field is generated between the electrodes 28 and 30.

The horizontal portion of the vibration member 34 is
A vibrates in the thickness direction due to an alternating electric field acting between the electrodes 28 and 30.

As the vibration generating means 24, any means can be used as long as it generates vibration in response to an electric signal input from the signal generating means 32, and a piezoelectric material, a magnetostrictive material, a mechanical actuator, or an electrostatic force is applied. An actuator or the like can be applied. Among them, piezoelectric materials are widely used as functional materials for ink jet printers, and are most suitable because advanced manufacturing techniques have been established.

In particular, as described above, the electrodes 28 and 30
Piezoelectric vibrating part 34A vibrating due to the alternating electric field generated between
As quartz, lead zirconate titanate (PZT), titanium
Barium titanate BaTiO_Three, Lead niobate PbNb_TwoO
₆, Bismuth germanate Bi₁₂GeO₂₀, Lithium niobate
Lithium LiNbO_Three, Lithium tantalate LiTaO _Three
Such as polycrystal and single crystal, and piezoelectric such as ZnO and AlN
Thin film, polyurea, PVDF (polyvinylidene fluoride)
Piezoelectric polymer such as PVDF copolymer, or PZT
Uses composites of inorganic piezoelectric materials such as
Can be.

The vertical portion of the vibration member 34 is
0 has a predetermined thickness in the width direction (the left-right direction in FIG. 1),
The vicinity of the distal end portion 34C is a cantilever-like elastic portion 34B that can elastically bend and vibrate. Also, the elastic portion 34
The height of B depends on the surface tension of the ink 20 stored in the ink chamber 18 and the surface tension of the ink 20 and the ink 20 and the vibration member 3.
4 has a predetermined height so as to come into contact with the vicinity of the tip portion 34C of the elastic portion 34B due to affinity (wetting) with the surface of the ink 4 and gravity acting on the ink 20.

Accordingly, the piezoelectric vibrating portion 34A of the vibrating member 34
Is vibrated in its thickness direction, this vibration is directly transmitted to the elastic portion 34B without being attenuated, and the elastic portion 34B bends and vibrates in its thickness direction (direction of arrow A). In particular, the vicinity of the distal end portion 34C of the elastic portion 34B undergoes bending vibration with a large amplitude. As a result, ink droplets are ejected from the thin film of the ink 20 formed on both sides of the elastic portion 34B in the thickness direction, and fly toward recording paper as a recording medium.

As the elastic portion 34B, a piezoelectric vibrating portion 34A
(Vibration in the thickness direction) can be converted into bending vibration, and the material, shape, and the like are not particularly limited as long as an amplitude sufficient for drop ejection can be generated near the tip.

In particular, the recording head 10 according to the present embodiment
Then, a part of the vibration member 34 is a piezoelectric vibration part 34A,
Another part is an elastic part 34B (in other words, an elastic member that causes ink droplets to fly by bending vibration also serves as the piezoelectric vibrating part 34A of the vibration generating means 24).
The vibrating member 34 needs to be selected from a material that performs both the function as the piezoelectric vibrating part 34A and the function as the elastic part 34B. However, the above-described quartz, lead zirconate titanate (PZT), and barium titanate BaTiO ₃ , Lead niobate PbNb ₂ O ₆ , bismuth germanate Bi ₁₂ GeO
₂₀ , polycrystalline or single-crystalline materials such as lithium niobate LiNbO ₃ and lithium tantalate LiTaO ₃ , ZnO and A
A piezoelectric thin film such as 1N, a piezoelectric polymer such as polyurea, a copolymer of PVDF (polyvinylidene fluoride) or PVDF, or a composite of an inorganic piezoelectric substance such as PZT and a piezoelectric polymer can be used. .

The flying range of ink droplets is limited to a narrow range by making the vicinity of the distal end portion 34C of the elastic portion 34B gradually taper in the plate thickness direction or the width direction toward the distal end portion 34C. In addition, variation in the flying direction of the ink droplet can be reduced.

The vibrating member 34 is first bent to form a substantially L-shape having a piezoelectric vibrating portion 34A and an elastic portion 34B, and then the electrodes 28, 3
0 may be attached, but the electrodes 28 and 30 are first attached to a part of the flat plate before the bending process (the bonded portion becomes the piezoelectric vibrating portion 34A), and then the bending process is performed. About L
A portion where the electrodes 28 and 30 are not attached may be used as the elastic portion 34B.

The electrodes 28 and 30 also cut to the desired size may be adhered to the vibration member 34 cut to the desired size in advance.
And a plate material of the same material as the electrodes 28 and 30 are prepared, and the electrode material 28 and
After sticking the plate material of No. 30, it may be cut into a desired size by laser processing, etching or the like. in this way,
By performing the cutting in a later step, the vibration member 34 and the electrode 28,
30 can be formed into a desired shape at one time, and the number of manufacturing steps is reduced.

The surfaces of the vibration generating means 24 and the elastic portion 34B are covered with a thin film 36 of PTFE or the like.
It is protected from deterioration, corrosion, foreign matter adhesion, etc. due to interference with the like.

Next, the recording head 10 according to this embodiment
The operation and operation of the above will be described. First, as shown in FIG.
The case where dots are recorded by flying the ink droplets 46 will be described. That is, when an image signal is input to the signal generation unit 32 pixel by pixel based on the input image information, a drive signal of the vibration generation unit 24 is generated based on the image signal.

The vibration generating means 24 determines the rigidity of the substrate 12,
Thickness of piezoelectric vibrating portion 34A, piezoelectric characteristics, and elastic portion 34
Unique resonance frequency f ₀ determined by the size and rigidity of B
Having. Therefore, when the voltage is applied from the signal generating means 32 to the vibration generating means 24 at a frequency f equal to or an integer multiple of f ₀ , the elastic portion 34B can be vibrated efficiently. Of course, the drive frequency is not limited to this, and may be any frequency as long as the elastic portion 34B can be bent and vibrated at a desired frequency. Further, the waveform of the drive signal has the elastic portion 3 as shown in FIG.
4B, a continuous AC voltage equal to the excitation frequency of FIG.
A continuous pulse voltage as shown in (B) can be used. Further, the excitation cycle as shown in FIG.
A burst signal in which at least one or more continuous waveforms are connected for one pixel may be used as a burst wave. However, in this case, each waveform is not limited to a rectangular wave as shown, but may be a sine wave or a triangular wave. In particular, by using a burst wave, a burst wave having a resonance frequency f ₀ is applied to the vibration generating means 24 for a short time, and
4B can be vibrated. In addition, it becomes possible to eject minute ink droplets 46 by the burst wave. On the other hand, when the alternating voltage is continuously applied, relatively large continuous ink droplets are continuously ejected.

The energy for ejecting the ink droplets 46 is determined by the number of waveforms (the number of bursts) having one cycle of the excitation of the vibration generating means 24 and the applied voltage. If the number of bursts is increased, it is possible to eject the ink droplet 46 at a relatively low voltage, while if the number of bursts is reduced,
Although the voltage required for discharging the ink droplet 46 is slightly higher, the ink droplet 46 having a higher flying speed can be discharged.

When the driving signal having such a predetermined waveform is applied from the signal generating means 32 to the vibration generating means 24 and the piezoelectric vibrating part 34A vibrates, the elastic part 34B resonates and the bending vibration is caused in the direction of arrow A. Do. As shown in FIG. 3, due to the surface tension of the ink 20, the affinity (wetting) between the ink 20 and the surface of the elastic portion 34B, the gravity acting on the ink 20, and the like, the vicinity of the tip portion 34C of the elastic portion 34B A thin film having a predetermined liquid thickness (several μm to several hundred μm) in the vibration direction (the direction of arrow A) is formed. Then, due to the bending vibration of the elastic portion 34B, a capillary wave is generated in this thin film portion.

As shown in FIG. 5, at a certain time t,
On the surface of the ink 20, a capillary wave 44 such that the wavelength λ is W = 2λ with respect to the width (width in the direction of arrow B) W of the surface of the elastic portion 34B perpendicular to the bending vibration direction (direction of arrow A).
There are two peaks. Time t + Δ after elapse of minute time Δt
At t, as shown in FIG.
One mountain of ink ridges is formed from between the four regions, and these ridges are separated and one ink droplet flies.

By repeatedly applying the driving signal from the signal generating means 32 to the vibration generating means 24, the ink droplets 46 fly one by one from the elastic portion 34B corresponding to the driving signal.

As described above, in order to stably fly the ink droplets 46 one by one, the tip portion 34C of the elastic portion 34B is required.
In the vicinity, when the width of the elastic portion 34B on a plane (vibration surface 34D) perpendicular to the bending vibration direction is W and the value calculated by the following equation is λ, at least a portion near the tip portion 34C is provided. It is desirable that the width W be approximately 2λ.

[0046] lambda = [8πσ / (ρf _e ^{2)] 1/3} × 10 ^{4 (μm)} ··· Equation (1) where, sigma is the ink surface tension (mN / m) [rho is the ink density ( g / cm ³ ) f _e is the excitation frequency (Hz) The above equation (1) is described in a general reference book, for example, Chika Chika, “Ultrasonic Spraying” (Sankaido), Chapter 7, Section 2, the capillary wave It is described as an equation giving the wavelength.

The width W is preferably as close as possible to the value of 2λ, and is preferably in the range of 1.2λ to 2.4λ.
The minute ink droplet thus generated stably flies in a direction perpendicular to the vibration surface 34D of the elastic portion 34B by an input signal having an appropriate waveform input from the signal generation means 32 to the vibration generation means 24. .

If the width W is less than 1λ in the vicinity of the tip portion 34C of the elastic portion 34B, it becomes difficult to generate a capillary wave, and it is not necessary to increase the excitation voltage of the signal generating means 32 or increase the number of bursts. And ink drops do not fly. Even if the ink droplet flies, it is difficult to fly stably.

On the other hand, even when the width W is 3λ or more in the vicinity of the distal end portion 34C of the elastic portion 34B, a capillary wave is hardly generated. In this case, similarly to the above, the capillary wave can be generated by increasing the excitation voltage of the signal generating means 32 or increasing the number of bursts. In this case, three or more peaks are generated. A plurality of ink droplets fly at a time, and cannot fly one by one.

As described above, in the recording head 10 according to the present embodiment, the minute ink droplets 46 are not restricted by the nozzles.
Can be generated, and a high-quality and stable recording apparatus without nozzle clogging can be realized.

The recording head 10 according to the present embodiment
Then, the vibration generating means 24 is
(Piezoelectric vibrating part 34A) and an elastic member (elastic part 34) that causes ink droplet 46 to fly by bending vibration near the tip.
B). For this reason, the number of parts is reduced as compared with the case where the vibrator and the elastic member are formed separately. Further, since no bonding surface or another member (for example, an adhesive) is interposed between the piezoelectric vibrating portion 34A and the elastic portion 34B, the vibration of the piezoelectric vibrating portion 34A is directly transmitted to the elastic portion 34B without being attenuated. . Therefore, compared to the case where the elastic member is formed separately from the vibration generating means, the elastic portion 34B
The amplitude of the bending vibration in the vicinity of the tip of the ink droplet 46 can be further increased, and the ink droplet 46 can fly sufficiently with small energy.

In addition, since there is no need to fix the elastic member to the vibration generating means 24, the manufacturing process of the recording head 10 can be simplified. Further, the vibration generating means 24 of the elastic portion 34B
And no positional deviation (deterioration in mounting accuracy) with respect to.

FIG. 7 shows a schematic configuration of a recording head 50 according to the second embodiment of the present invention. The recording head 50 differs from the recording head 10 according to the first embodiment in the configuration of the vibration generating means and the vibration member. Hereinafter, the same elements and members as those of the recording head 10 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the recording head 50, the substrate 12
The vibrating member 52 stands upright. Vibration member 52
Is not L-shaped when viewed from the front like the vibration member 34 according to the first embodiment, but is formed in a flat plate shape as a whole.

An electrode 2 is provided at the lower part on both sides of the vibration member 52.
8, 30 are stuck. Therefore, the lower portion of the vibration member 52 (the portion where the electrodes 28 and 30 are adhered) is
2A, the piezoelectric vibrating portion 34A and the electrode 28,
The vibration generating means 54 is constituted by the combination 30 and the vibration generating means 54. The lower end of the vibration generating means 24 is fixed to the substrate 12.

The upper part of the vibration member 52 (the electrodes 28, 3
0 is affixed in the thickness direction (arrow A in FIG. 7).
The elastic portion 52B can bend and vibrate in the (direction). Therefore, the vibration generating means 54 is
(Piezoelectric vibrating part 52A) and an elastic member (elastic part 52B) that causes ink droplets 46 to fly from a thin film of ink 20 formed on the surface by bending vibration.

The height of the vibration member 52 is such that the upper end of the vibration member 52 is placed on the surface of the ink 20 in the ink chamber 18.
The height is set to a predetermined height so as to be in contact with the surface tension of the ink, the affinity (wetting) between the surface of the vibration member 52 and the ink 20, the gravity acting on the ink 20, and the like.

In the recording head 50, similarly to the recording head 10 according to the first embodiment, when the alternating voltage generated by the signal generating means 32 based on the image signal is input to the vibration generating means 54, The piezoelectric vibration part 52A vibrates,
The vicinity of the distal end portion 52C of the elastic portion 52B undergoes large bending vibration. A thin film having a predetermined liquid thickness (several μm to several hundred μm) in the vibration direction (the direction of arrow A) is formed near the distal end portion 52C of the elastic portion 52B. Then, a capillary wave 44 is generated in the thin film portion, and the ink droplet 46 flies.

Further, similar to the recording head 10 according to the first embodiment, since the piezoelectric vibration part 52A and the elastic part 52B are constituted by the integral vibration member 52, the number of parts can be reduced. it can. Further, the piezoelectric vibrating section 52
Since no bonding surface or another member (for example, an adhesive) is interposed between A and the elastic portion 52B, the vibration of the piezoelectric vibrating portion 52A is directly transmitted to the elastic portion 52B without being attenuated. Therefore, the amplitude of the bending vibration in the vicinity of the tip of the elastic portion 52B can be further increased, and the ink droplet 46 can be caused to fly sufficiently with small energy.

In addition, the elastic portion 52B is
Since there is no need to fix the recording head 50, the manufacturing process of the recording head 50 can be simplified. There is no displacement of the elastic portion 52B with respect to the vibration generating means 24 (deterioration of mounting accuracy).

Further, since the vibration member 52 does not need to be bent unlike the vibration member 34 according to the first embodiment, the manufacturing process of the vibration member 52 is simplified. In particular, even when a material (for example, PZT or the like) that is difficult to bend is used as the vibration member 52, the manufacture of the vibration member 52 becomes easy.

FIGS. 8 and 9 show a recording head vibration generating means 62 and an elastic part 6 according to a third embodiment of the present invention.
4 is shown. This recording head differs from the recording head 50 according to the second embodiment only in the configuration of the vibration generating means 62 and the vibration member 66. Hereinafter, the same elements and members as those of the recording head 10 according to the first embodiment and the recording head 50 according to the second embodiment are denoted by the same reference numerals, and description thereof is omitted (FIG. 9). In the drawing, the illustration of the thin film 36 is omitted for convenience of illustration.)

In this recording head, as shown in FIG.
The lower end portions of the plurality of vibrating members 66 are connected by a connecting plate 68 to form a single comb-shaped vibrating body 70 as a whole. And a plurality of vibrating members 66 and a connecting plate 68,
Is configured). Further, the lower end of the connecting plate 68 is fixed to the substrate 12, and the vibration member 66 has a cantilever shape standing upright from the substrate 12. Therefore, the portion of the vibration member 66 to which the electrodes 28 and 30 are adhered acts as the piezoelectric vibration portion 66A, and the piezoelectric vibration portion 66A
And the electrodes 28 and 30 constitute the vibration generating means 62. The portion of the vibrating member 66 where the electrodes 28 and 30 are not adhered is a vibrating portion 66B that is excited by the piezoelectric vibrating portion 66A and bends and vibrates to fly ink droplets.

For this reason, the plurality of vibration members 66 can be integrally formed, and the recording head 10 according to the first embodiment can be formed.
Also, the number of components is smaller than that of the recording head 50 according to the second embodiment. By fixing the vibrating body 70 in which the plurality of vibrating members 66 are integrated into the shape of the substrate 12, it is possible to reduce the variation in the mounting position of each vibrating member 66 and mechanical properties.

The vibrating member 70 is formed by forming a vibrating member 66 of a predetermined shape by subjecting a plate made of stainless steel or the like to laser processing, etching, or the like, and then attaching the electrodes 28 and 30 to the respective vibrating members 66. Can be manufactured. Also,
A plurality of vibrating bodies 70 can be stacked and fixed and processed, and the vibrating bodies 70 can be prevented from warping or returning during processing, and can be processed with high processing accuracy.

In any of the manufacturing methods, the vibrating body 70 having the plurality of vibrating members 66 can be manufactured in one process, so that the labor and cost required for manufacturing can be reduced.

FIG. 10 shows a recording head 80 according to a fourth embodiment of the present invention. This recording head 8
At 0, the configuration of the ink chamber is different from that of the recording head 10 according to the first embodiment. Hereinafter, the same components and components as those of the recording head 10 according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the recording head 80, the hollow portion 8 is provided inside.
4 has a case 82 formed therein. One of the side walls 86 (the right side in FIG. 10) constituting the hollow portion 84
Has an opening 88 formed therein.

A vibration member 94 is erected from substantially the center of the hollow portion 84 in the width direction (horizontal direction in FIG. 10), and a range surrounded by the bottom 82A of the case 82, the side wall 86 and the vibration member 94 is provided. , And an ink chamber 90. A predetermined amount of ink 20 is stored in the ink chamber 90. Therefore, the bottom portion 82A of the case 82 also functions as the substrate 12 according to the first embodiment.

An ink supply passage 92 is formed in the bottom 82A of the case 82. The ink 20 is supplied from an ink tank (not shown) through an ink supply path 92, and a predetermined amount of the ink 20 is always stored in the ink chamber 90.

The electrode 2 is provided at the lower part on both sides of the vibration member 94.
8, 30 are stuck. Therefore, the portion of the vibration member 94 to which the electrodes 28 and 30 are attached is the piezoelectric vibration portion 94.
A, the piezoelectric vibrating portion 34A and the electrode 28,
The vibration generating means 96 is constituted by 30. Electrode 2
Portions where no 8 and 30 are attached act as elastic portions 94A.

When an alternating voltage corresponding to an image signal is input from the signal generating means 32 connected to the electrodes 28 and 30, the piezoelectric vibrating portion 94A vibrates according to the input signal. Then, the vibration of the piezoelectric vibrating section 94A causes the elastic section 9 to move.
4B is excited at the resonance frequency and bends and vibrates, so that the ink droplet 46 is ejected from the thin film of the ink 20 formed on one side (the ink chamber 90 side) in the thickness direction of the elastic portion 94B, and the opening 8
8 and flies toward a recording sheet as a recording medium.

In the recording head according to each of the above embodiments, each of the vibration generating means 24, 54, 62, 9
6 and the elastic portions 34B, 52B, 66B, 94B, one ink chamber 18, 90 has been described as an example, but the ink chambers 18, 90 are divided by a plurality of partition walls. Is also good. Thereby, the adjacent vibration generating means 24, 34, 62, 96 and the elastic portions 28B, 52B,
Between 66B and 94B, the vibration of the liquid level of the ink 20 does not affect each other. For this reason, it is possible to prevent crosstalk that occurs due to interference between the vibrations of the liquid levels. In addition, the partition is provided with each vibration generating means 2.
4, 34, 62, and 96 may be formed,
It may be formed for each of the plurality of vibration generating means 24, 54, 62, 96. Further, the partition does not need to be erected from the substrate 12, for example, is formed only in the vicinity of the liquid level of the ink 20, and each ink chamber 18 communicates below the ink chamber 18. It may be.

In addition, in the recording head according to each embodiment, when the vibrating member is in the vibrating state, the electrodes 28, 3
It is also possible to detect the state of vibration of these vibration members from the waveform of the voltage at both ends of zero. Thus, by detecting the vibration state of the vibration member, the input timing of the next alternating voltage can be controlled according to the state of occurrence of the residual vibration after the input of the alternating voltage. For example, if the next alternating electric field is applied after an integral multiple of the period of the alternating electric field, it is possible to prevent the new vibration from being canceled out by the residual vibration or the amplitude from being reduced. Further, by applying an electric field having a phase opposite to that of the residual vibration, the residual vibration can be promptly reduced.

[0075]

EXAMPLES The present invention will be described in more detail with reference to Examples. However, needless to say, the present invention is not limited to the following embodiments. (Example 1) In Example 1, the recording head 10 according to the first embodiment was used to fly the ink droplets 46 to record dots on the recording material.

As the vibration member 34 of the recording head 10,
Approximately 1 formed by ion beam etching
A 0 μm thick lead zirconate titanate (PZT) was used.
The piezoelectric vibrating portion 34A is subjected to a polarization process, and the electrodes 28, 3
When a voltage was applied during the period of 0, the vibration was made in a direction perpendicular to the electrode surface.

The electrodes 28 and 30 had a two-layer structure made of chromium having a thickness of 0.05 μm and gold having a thickness of 1 μm.
The frequency for exciting the vibration generating means 24 was 190 kHz.

When the ink droplets 46 were ejected from the recording head 10 having the above configuration, the minute ink droplets 46 could be ejected stably, and a high-resolution image could be obtained. (Example 2) In Example 2, ink droplets 4 were formed using the recording head according to the third embodiment (see FIGS. 8 and 9).
6 was made to fly, and dots were recorded on the recording material.

As the vibration member 66 of the recording head 10,
In the same manner as in the first embodiment, the electrodes 28 and 30 are subjected to a polarization treatment using lead zirconate titanate (PZT) having a thickness of about 10 μm formed by the ion beam etching method.
When a voltage is applied during the period, the piezoelectric element vibrates in a direction perpendicular to the electrode surface.

The vibration member 34 and the electrodes 28 and 30 have the same configuration as in the first embodiment, and the frequency for exciting the vibration generating means 24 is also 190 kHz.

When the ink droplets 46 were ejected from the recording head having the above configuration, the minute ink droplets 46 could be ejected stably, and a high-resolution image could be obtained.

[0082]

According to the first aspect of the present invention, there is provided an ink chamber for storing ink, and a piezoelectric vibrating portion disposed in the ink chamber and partially vibrating when an alternating electric field is applied. A part of the vibrating member is a resilient part which bends and vibrates in accordance with the vibration of the piezoelectric vibrating part, which causes ink droplets to fly from an ink thin film formed on the surface by the bending vibration and adheres the ink droplet to a recording medium. And an exciting unit that excites the piezoelectric vibrating unit with an input signal input corresponding to an image signal, so that a high-resolution image can always be accurately recorded. The vibration of the vibration member is transmitted with high vibration efficiency without being attenuated.

According to the second aspect of the present invention, in the first aspect of the present invention, since the exciting means is an electrode for applying an alternating electric field corresponding to an image signal to the piezoelectric vibrating portion, the structure has a simple structure. In addition, the piezoelectric vibrating section can be vibrated.

According to a third aspect of the present invention, in the second aspect of the invention, a plurality of the vibrating members are arranged in the ink chamber and a plurality of the vibrating members are integrally formed. The number of points can be reduced, and the accuracy of the mounting position of the vibration member can be increased.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a recording head according to a first embodiment of the present invention.

FIG. 2 is a partially cutaway perspective view showing the recording head according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating flying of ink droplets from a recording head according to the present invention.

FIGS. 4A to 4C are diagrams showing voltage waveforms of a drive signal applied from a signal generation unit to a vibration generation unit of the recording head according to the present invention.

FIG. 5 is an explanatory diagram illustrating a state in which a capillary wave is generated from a recording head according to the present invention.

FIG. 6 is an explanatory diagram illustrating a state where a capillary wave is generated from the recording head according to the present invention.

FIG. 7 is a cross-sectional view illustrating a recording head according to a second embodiment of the present invention.

FIG. 8 is a sectional view showing a main part of a recording head according to a third embodiment of the present invention.

FIG. 9 is a perspective view showing a main part of a recording head according to a third embodiment of the present invention.

FIG. 10 is a sectional view showing a recording head according to a fourth embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Recording head 18 Ink chamber 20 Ink 28 Electrode (excitation means) 30 Electrode (excitation means) 34 Vibration member 34A Piezoelectric vibration part 34B Elastic part 46 Ink droplet 50 Recording head 52 Vibration member 52A Piezoelectric vibration part 52B Elastic part 66 Vibration member 66A Piezoelectric vibrating section 66B elastic section 80 recording head 90 ink chamber 94 vibrating member 94A piezoelectric vibrating section 94B elastic section

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Susumu Hirata 430 Nakai-cho, Nakai-cho, Ashigara-kami, Kanagawa Prefecture Inside Fuji Xerox Co., Ltd. Inside

Claims (3)

[Claims] An ink chamber in which ink is stored; a piezoelectric vibrating part arranged in the ink chamber, part of which vibrates when an alternating electric field is applied, and another part of which is a piezoelectric vibrating part. A vibrating member, which is a resilient portion for causing ink droplets to fly from an ink thin film formed on the surface by the bending vibration and causing the ink droplets to adhere to a recording medium due to the bending vibration, and an input corresponding to an image signal An exciting means for exciting the piezoelectric vibrating section by the input signal obtained. 2. The recording head according to claim 1, wherein said excitation means is an electrode for applying an alternating electric field corresponding to an image signal to said piezoelectric vibrating section. 3. The recording head according to claim 1, wherein a plurality of the vibration members are arranged in the ink chamber, and a plurality of the vibration members are formed integrally.