JP3438544B2 - Inkjet recording head - Google Patents

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention
Ink jet for printing by discharging droplets such as droplets
Print head. 2. Description of the Related Art Droplets, particularly ink drops, on a recording medium
Is a typical recording method for printing by discharging
There is a method that uses chirping. Here, the nozzle type recording method
Are on-demand type and continuous flow type. [0003] The on-demand type is a type that responds to recorded information.
A method for printing by intermittently ejecting ink from the nozzle
Typical examples are the piezo oscillator type and the thermal type.
There is. The piezo oscillator type uses a piezoelectric
Deformation of a piezoelectric element by applying a pulse voltage to the element
Changes the ink pressure in the ink chamber
And eject ink drops to form dots on the recording medium.
It is to be recorded. Thermal type is installed in the ink chamber
Heating the ink with a heating element
Discharge ink drop from nozzle by bubble,
This is to record dots on a recording medium. On the other hand, the continuous flow type applies pressure to ink
While continuously ejecting ink from the nozzle,
Vibration is applied to the ink column by the oscillating element, etc.
And selectively charge and deflect droplets
The recording is performed by However, recently, 600 to 720 dots / a
And high-resolution printing of about
In order to satisfy such requirements, the dot diameter on the recording medium must be adjusted.
It is necessary to reduce the size, and the conventional nozzle-type printing method
Is the diameter of the ink drop ejected by reducing the nozzle diameter
Need to be smaller. However, when the nozzle diameter is reduced,
Nozzle due to dust and dust, drying of ink surface inside nozzle
Clogging and changes in ink ejection direction due to these
And the image quality on the recording medium is defective. That
The required solution by reducing the nozzle diameter.
It is difficult to achieve a dot diameter corresponding to the image resolution. [0007] Therefore, a problem caused by such a nozzle.
As a solution to the problem, vibration or
Using acoustic waves, eject ink drops on the surface to be printed
Several recording methods for performing printing have been proposed. [0008] As a first recording method without using a nozzle,
Is disclosed in U.S. Pat. No. 4,308,547.
The vibration generated by the vibrator is
Focus on one point on the free surface and eject ink drop
There is a method. As an acoustic lens, the piezoelectric body itself is
And disclosed in JP-A-3-200199.
As shown in the figure, the phase Fresnel
The one using a lens is used. Acoustic lens has shape and wave
Convergence and divergence are opposite to those of optical lenses, and
Since the wave diverges in the lens, use a concave lens
Is desirable. [0009] The diameter of the ink drop propagates through the ink.
To the focused diameter when the vertical waves are focused on the free surface of the ink
The focusing diameter d is substantially equal to the driving frequency of the vibrator.
f, if the F value of the lens is F, d to F / f. What
The wavelength of the longitudinal wave propagating in the ink is λ, and its propagation speed
Is v, between these and the driving frequency f of the vibrator
Has a relationship of v = f · λ. Therefore, for example, the drop diameter (convergence
Diameter) d = 15μm very small ink drop
When trying to discharge, the F value of the lens is set to 1.
And the propagation velocity v of the longitudinal wave in the conventional low-viscosity aqueous ink is
It is almost 1500 m / sec. To respond to this,
When the driving frequency f of the rotor is about 100 MHz,
To a higher frequency. The F value of the lens is
It is practically difficult to make it extremely small due to various problems.
Therefore, when trying to make the drop diameter d smaller,
Generally, it is necessary to drive the vibrator at an extremely high frequency.
You. As described above, in the first recording method, 100
Must drive multiple transducers at high frequencies around MHz
That the driving means is generally expensive.
This causes a problem on the strike. In addition, the viscosity of the ink is
Changes, the drop diameter fluctuates, or ink drops
If ink cannot be ejected due to drying or solidification of itself
There is a quality problem. As a second recording method without using a nozzle,
Uses the acoustic horn to ink the vibrations generated by the vibration generation mechanism.
Focus on one point on the free surface and eject ink drop
There is a method. For example, see the above-mentioned US Pat.
In the specification of No. 7, the vibration generating mechanism is used instead of the concave lens.
The vibration is focused by the acoustic horn formed in the
Thin ink that is transported on the belt
This vibration is applied to the film to eject ink drops.
Is shown. Here, the discharge
Output will be generated. A similar technique is disclosed in Japanese Patent Laid-Open No.
No. 8050 discloses a sound collector 95 as shown in FIG.
Is provided on the piezoelectric body 91. Sound collector 9
5 is a piezoelectric body 91 and an electrode for applying a voltage thereto.
Formed on a vibration generating mechanism 94 composed of poles 92 and 93,
It is arranged in an ink reservoir 99 holding the ink 96.
You. The sound collector 95 has a tapered shape as shown in FIG.
Take. In this case, the distortion incident from the bottom of the sound collector 95
As the sound propagates through the sound collector 95, its amplitude is amplified.
The large-amplitude wave collected by the sound collector 95 is
And the generated longitudinal waves push the ink free surface 97
And the ink drop 98 is ejected
I have. However, US Pat. No. 4,308,547
And Japanese Patent Application Laid-Open No. 4-168050, the sound collector or
Uses an acoustic horn, but its size and drive
Conditions, or vibration modes, and even small diameter drops
It does not say whether this can be achieved. With respect to the acoustic horn, generally speaking,
In the field, a sound collector (or acoustic horn) due to resonance
When the tip of the nozzle is vibrated to a large amplitude to obtain the discharge force
In this case, the length (height) of the sound collector in the vertical section direction is the vibration wave
It is known that the length must be an integral multiple of 1/2
I have. Therefore, in the method shown in FIG.
In order to produce a high density recording element, the sound collector 15 was made smaller.
If you try to do so, the wavelength of the vibration wave must also be shortened,
The driving frequency of the vibration generating mechanism 2 must be increased.
No. Therefore, a recording element having a realistic density can be manufactured.
In order to manufacture, as in the first recording method, several tens of MH
Vibration generator with high frequency of about 100MHz from z
It is necessary to drive the structure. Therefore, the energy in the ink
Energy attenuation and drive circuits are expensive.
You. Also disclosed in U.S. Pat. No. 4,308,547.
With a belt in contact with the tip of the acoustic horn as
It is practically difficult to transport the ink thin film stably,
Outgoing drop diameter is also easy to vary. As a third recording method using no nozzle,
The so-called electrostatic suction method that uses electrostatic force as the ejection force
Yes, and further form the ink meniscus (ink bump)
One that uses vibration to achieve this is known. For example, Japanese Patent Application Laid-Open No. 62-222853
To make the recording needle protrude from the ink surface,
Has been shown to give ultrasonic energy that propagates in
I have. According to this, ultrasonic flow (acoustic)
(streaming) phenomena, the in contact with the recording needle
The needle moves toward the tip of the recording needle, and a convex
Is formed. In that state,
Apply an electrostatic field between the substrate and the back electrode to tear off the ink
On the recording medium placed between the recording needle and the back electrode.
Land the ink drop. According to this method, recording
To form an ink meniscus at the tip of the needle, a conventional static
Form smaller ink drops than electro-suction method
it can. Also, Japanese Patent Application Laid-Open No. 56-28867 discloses
With the electrostatic field applied between the needle electrode and the back electrode.
When the image signal is applied to the needle electrode,
An electrostatic attraction method is shown. This way,
Ink can be stably formed into particles. However, in the electrostatic suction method, humidity
Fluctuations in the dielectric thickness of the recording medium due to
Drops formed due to variations in surface roughness, etc.
This causes a problem that the diameter of the probe varies. In addition, drop
Variations in diameter also cause variations in dot position on the recording medium
Occurs. [0021] These problems are solved.
As a new recording apparatus, an ink as shown in FIG.
A jet recording device has been proposed by the applicant.
FIG. 12A shows the proposed inkjet recording apparatus.
FIG. 12B is a schematic side view, and FIG.
You. This ink jet recording apparatus has a sharp elastic member.
Is vibrated in the direction of aa ′ shown in FIG.
The vibration energy is applied to the free surface 8a in contact with the tip 7a.
The droplets 9 are discharged by transmitting the energy. This
Depends on the nozzle when using an inkjet recording head
Control the size of the ink droplets without using
It is said that it has excellent lugi efficiency and wide ink properties that can be used.
It has the following features. However, the proposed ink jet
The recording head has an elastic member as shown in FIG.
The side cross-sectional shape of No. 7 is the right and left
The vibration when the image signal is input.
The start direction is not constant, the ejection timing of ink droplets, and
There is a stability problem that the position may vary.
ing. The problem was that dots were recorded on the recording medium
Appears as dot misalignment in
May cause deterioration such as sharpness of edge and color shift.
Cause it to An object of the present invention is to prevent clogging and drying of a nozzle.
No discharge failure due to energy efficiency
And the nozzles are not affected by the ejection history or adjacent nozzles.
Excellent drop ejection stability, and
Small variation in dot diameter and good dot position accuracy
Inkjet recording head with characteristics such as
Is to provide. The object of the present invention is to provide a pixel signal.
Vibration generating means that vibrates correspondingly, and excitation of the vibration generating means
Has a cantilever structure that bends and vibrates according to the
Beam structure is defined by a plane perpendicular to the neutral axis of bending deformation
Cut cross section is asymmetric with respect to the neutral plane of bending deformation
Capillary waves are generated on the surface of the elastic member and ink.
To fly the ink and attach it to the recording medium.
Achieved by the inkjet recording head
You. Here, the neutral axis and the neutral plane are shown in FIGS.
This will be described with reference to FIG. 13 to 15 show that the cantilever is bent.
FIG. 1 is a schematic view showing a state of deformed deformation.
3 is a side view of the bending cantilever, and FIG.
15 is a cross-sectional view taken along the line NN of FIG.
FIG. 3 is a perspective view of a cantilever beam. The beam is bent as shown in Fig. 13.
When it is shaped, as shown in FIG.
Bending stress is acting in the vertical direction. N- in FIG.
In the case of N cross section, the convex surface of the bent beam (right side of the beam in the figure)
Has a tensile strain on the concave surface (left side of the beam in the figure)
Has a compressive strain, and there is no stretch
Exists. This is called the neutral plane. Then, as shown in FIG.
The axis at which the neutral plane and the cross section intersect is called the neutral axis.
U. The ink jet recording head of the present invention
Is connected to a vibration generating mechanism (hereinafter referred to as a vibrator).
The elastic member has a cantilever structure with its connection as the base end.
You are. At least near the tip of the elastic member
In contact with the surface. The vibrator bends the elastic member to a vibration mode.
Excitation is performed by the frequency that resonates at
Therefore, the vicinity of the tip of the elastic member has a large amplitude.
You. The ink thickness in the vibration direction of the bending vibration is the tip of the elastic member.
In the vicinity, wetting of ink and elastic members and the effect of gravity
Thus, the thickness is formed to several μm to several hundred μm. by this,
The ink is strongly affected by the vibration, and the tip of the elastic member is extremely small.
A capillary wave is generated on the nearby ink surface. This cap
By the action of the spiral wave, it is possible to generate fine droplets. The vibration of the ink liquid surface caused by the capillary wave is utilized.
Use a vibrator to fly a single ink drop
Needs to be set to a predetermined value. To the vibrator
For every two to dozens of continuous waves
A wave (burst wave) in a mode that terminates the excitation
It is provided as an intermittent drive signal according to the signal. single
The wave number required to achieve the flight of the ink drop
Viscosity, surface tension, amplitude of applied vibration, frequency, etc.
Can be appropriately selected. Based on the above principle,
Small droplets are generated without nozzles and ink is not clogged
High-quality inkjet recording heads can be realized.
You. In particular, in the present invention, the bending of the cantilever structure is changed.
Cross section cut by a plane perpendicular to the neutral axis of the shape
However, it is asymmetrical to the neutral plane of bending deformation
The bending stiffness of the cantilever varies depending on the bending direction.
You. Therefore, when starting the bending vibration, multiple elastic
All directions in which the member starts to bend initially are the same
Is determined. For this reason, the ejection timing of the droplet
It is the same between the elements, and the position of the dots formed on the recording medium
The stability of the installation is improved. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS According to a first embodiment of the present invention,
The ink jet recording head will be described with reference to FIGS. 1 and 2.
I will tell. As shown in FIG. 1, a machine for generating vibration
A plurality of transducers 2 are formed in a row on a substrate 1 as a structure
Then, the elastic members 7 were formed on the respective vibrators 2. What
If the configuration is such that the vibrator can be supported, the substrate 1 is not used.
You may not. The material of the elastic member 7 is cyano.
Acrylic resin, epoxy resin, or fluorine resin
Various resins such as resins can be used. In addition, Si
O _Two , SiON or SiN, AlN, Al _Two O _Three What
The elastic member 7 may be formed of various inorganic materials such as
No. Also, Al, Fe, Ti, Cr, Au, Mo, Ti
The elastic member 7 is formed of W or the like or various alloys thereof.
You may. However, unlike various resins and metals, ink 8
To prevent corrosion during contact with _Two Inorganic film such as
It is desirable to protect those surfaces. Rice cake
, Resin, inorganic material and metal
May be used. In addition, vibration energy propagates efficiently
If possible, the tip and bottom of the elastic member 7 are made of different materials.
May be implemented. FIG. 2 is a sectional view taken along the line XX ′ in FIG.
FIG. As shown in FIG.
The most important piezoelectric body 3 in the vibrator 2 to be moved is a piezoelectric substrate.
It may be composed of a piezoelectric thin film. Also, piezoelectric
May be composed of a single layer or a multilayer. Piezoelectric
As the body 3, quartz, PZT, barium titanate BaT
iO _Three , Lead niobate PbNb _Two O ₆ , Bismuth gel money
Bi ₁₂ GeO ₂₀ , Lithium niobate LiNbO _Three , Ta
Lithium tantalate LiTaO _Three , Such as polycrystalline or single bond
Crystal, piezoelectric thin film such as ZnO or AlN, or
Liurea, PVDF (polyvinylidene fluoride) and PVDF
Piezoelectric polymer such as copolymer of
Using a composite of a piezoelectric material and a piezoelectric polymer
Can be. Of course, we design inkjet recording head
The optimal piezoelectric material according to the drive frequency set when performing
You have to choose. The frequency of the applied AC is a number
If it is between 10kHz and 1MHz, like PZT
Ceramic may be used, but when driving at higher frequency
Includes piezoelectric thin films such as ZnO that can handle high frequencies
You have to choose. Anyway, stable
It has a characteristic that can generate enough vibration in the vibrator 2.
Need to be. In addition, the piezoelectric material constituting the vibrator 2
The elastic member 7 may be formed by a body. The piezoelectric ceramic thin film 3 and the electrodes 4, 5
The vibrator 2 is made of a material such as the rigidity of the substrate 1 or the piezoelectric ceramic thin film.
Thickness and piezoelectric properties of membrane 3 and connected elastic members
7, a unique resonance frequency fo determined by the size, rigidity, etc.
Having. Therefore, the external driving means 12
Voltage of frequency f which is the same as fo or an integral multiple of fo is applied to child 2
To excite the vibrator 2. Here, 190k
Excited at Hz. The drive frequency can be any value.
However, at the resonance frequency fo or a frequency f that is an integral multiple thereof,
When driven, the elastic member 7 can be vibrated efficiently.
You. In this embodiment, the AC voltage is continuously applied.
Ink droplets, a relatively large continuous ink droplet is ejected.
When a burst wave is applied, minute ink
Drops are ejected. Here, the burst wave is shown in FIG.
As shown, a voltage change consisting of multiple cycles of waves is
This is caused intermittently. burst
By using the wave, the resonance frequency fo is applied to the vibrator 2 for a short time.
Can only be applied. However, the burst wave
Not only square wave like 3 (b) but also sine wave and triangle wave
Is also good. In this embodiment, each bullet
You may arrange | position and arrange | position the sexual member with a partition. Also ammunition
May be configured to supply ink to only one side of the conductive member.
I don't know. In this embodiment, as shown in FIG.
The thickness of the conductive member 7 decreases toward the tip of the cantilever.
And the surface of one side of the plate-like elastic member 7 is
It is mounted perpendicular to the surface. Elastic part
The bottom of the material 7 is a rectangle with a side of 400 μm and a thickness of 50 μm
And the height is 400 μm. At the tip 7a,
The side is 400 μm and the thickness is 20 μm. The vibrator 2 is made of PZT on a brass substrate 1.
Piezoelectric ceramic thin film composed of (lead zirconate titanate)
3 and electrodes 4 and 5 for applying a voltage to the
From the piezoelectric ceramic thin film 3 and the electrodes 4 and 5
On the vibrator 2 _Two Through a protective film 6 made of
To form an elastic member 7 made of a cyanoacrylate resin.
Done. Further, as shown in FIG.
In the vicinity, the ink 8 is mounted so as to be in contact with the ink surface 8a.
I filled it. The protective layer 6 provides insulation between the vibrator 2 and the ink 8.
It is a thing. Ink 8 is black having a viscosity of 2 mPa · s.
It is a color water-based ink. However, the ink has this property
Not limited to this, it can be used for general printers, etc.
For example, select viscosity, density, surface tension, etc.
I can do it. Use oily, two-part inks
You may. In the present embodiment, the elastic member 7 is
Is mounted vertically so that the elastic member
The relationship between the vibrator 7 and the vibrator 2 is not limited to this mode.
Even if it is tilted with respect to the surface of the plate 1, it should be installed parallel to the surface of the substrate 1.
You may. Further, the elastic member 7 itself is constituted by a vibrator.
It does not matter. The apparatus having the above-described configuration is provided with a 190 kHz size.
Of the AC voltage as a burst wave for six periods.
The vibrator 2 is vibrated in the direction of bb ′ in FIG.
Then, the elastic member 7 was vibrated in the aa 'direction. This
Observing the state of using a high-speed camera, the elastic member
7 is a mode in which the bending vibration of the cantilever vibrates in a dominant mode.
And the ink surface 8a in contact with the vicinity of the tip of the elastic member 7
Confirms that capillary waves (surface tension waves) are generated
Was done. And an amplitude of 30 Vp-p (highest and lowest amplitude)
At the drive voltage, as shown in FIG.
From the ink surface that touches one side of the edge, the ink drop 9
Discharge was observed. Ink drop at this time
The diameter of 9 was 20 μm. Further, the ink jet recording head shown in FIG.
Use and place at a distance of 1 mm from the tip of the elastic member
When ink 8 was flying and recorded on the recording paper
Dot diameter of 50 dots continuously printed from one elastic member 7
Has an average of 40 μm and a standard deviation of 1 μm.
On the other hand, the root mean square of the dot center of gravity
And the square of the relative displacement of the dot position in the nozzle arrangement direction
The average was 3 μm. On the other hand, according to the conventional example shown in FIG.
Printed on recording paper by inkjet recording head
I examined the dots. As a result, continuous printing from the same recording element
The average dot diameter of the 50 dots is 40 μm,
The difference was 1 μm.
The mean square of the displacement of the center of gravity is 10 μm,
Mean of the relative displacement of the dot position in each direction is also 10μ
m. In this way, the actual printing
The effect of the form was confirmed. The phenomena described above are considered by the present inventors.
It was discovered for the first time by insight and experiment.
This is because the elastic member 7 is bent and deformed as shown in FIGS.
The cross-sectional shape cut by a plane perpendicular to the neutral axis,
Asymmetrical to the neutral plane of bending deformation (hereinafter referred to as “elastic
Material is asymmetric).
You. As shown in FIG. 1, a plurality of vibrators 2 and elastic portions are provided on a substrate 1.
The sets of materials 7 are arranged side by side, and the external drive connected to each
When the vibrations are simultaneously excited by the driving means 12,
The elastic member 7 starts vibrating from the same side at the same time. this is,
Since the elastic member is asymmetric, all directions that are easy to bend
Of the elastic members, and the same
This is due to the start of bending vibration in the direction. Elastic part
Since there is no shift in the vibration start of the material 7, a plurality of ink droplets
Sometimes fly in the same direction and reach the recording medium almost simultaneously
You. For this reason, the head and the recording medium also have a relative speed.
Is moving in this relative movement direction,
No misalignment occurs, resulting in higher image quality
Can be realized. That is, this effect is caused by the vibration of the elastic member 7.
Begins to bend in multiple elastic members when
Are obtained because the directions are the same. Next, according to the second embodiment of the present invention,
FIG. 4 shows a side cross section of the elastic member of the ink jet recording head.
You. In the present embodiment, the elastic part connected on the vibrator 2
The material 7 is folded in the aa 'direction from the middle of the cantilever structure.
Bent into an L-shaped cross section. In other words, elastic
The member 7 is cut by a plane perpendicular to the neutral axis of bending deformation.
The cross-sectional shape of the cut
It is called. In the case of the second embodiment, the vibrator 2
If the excitation voltage is input, does the elastic member 7 tend to fall down?
Start vibration. Vibrator 2 pushes elastic member 7 upward
In the case where the vibration starts in the shaking direction (direction B in the figure),
The bending vibration starts from the direction a. An ink jet printer according to a third embodiment of the present invention
FIG. 5 is a sectional view of the elastic member of the jet recording head. Figure
5 (a) is an inkjet recording apparatus according to the present embodiment.
FIG. 5B is a cross-sectional view of the same front side.
It is. In the present embodiment, a singular point is provided at the tip of the elastic member 7.
The feature is that an end portion is provided. Plate elasticity
One surface of the member 7 is perpendicular to the surface of the vibrator 2
So that it is attached. Other configurations are the first implementation
The description is omitted because it is the same as the embodiment. The thickness of the elastic member 7 is from the bottom to the tip 7a.
Once thin. In the present embodiment, the bottom
Is a rectangle with a side of 400 μm and a thickness of 50 μm,
The height is 400 μm. At the tip 7a, the thickness is 20μ
m, but a sharp tip at an angle of 90 degrees at the center of the side
Is formed. The material of the elastic member 7 is
A mold made of a fluorine-based resin on the surface of the vibrator 2 using a related resin.
After processing using, processing so that the width becomes 400μm
It was done. In this embodiment, the first embodiment will be described.
The tip of the elastic member is sharpened so that the elastic part
The material vibration can be locally applied to the ink liquid level.
Therefore, the ink ejection area can be limited to a narrower range.
The advantage is that Next, the fourth embodiment of the present invention will be described.
FIG. 6 is a sectional view of the elastic member of the ink jet recording head.
You. FIG. 6A shows an ink jet according to the present embodiment.
FIG. 6B is a side sectional view of the recording apparatus, and FIG.
It is sectional drawing. The ink jet recording head according to the present embodiment.
The surface of one side of the elastic member 7 is opposed to the surface of the vibrator 2.
Mounted vertically, the other side is curved
It is characterized in that it is configured as described above. Again, in this case,
The elastic member 7 is bent by a plane perpendicular to the neutral axis of the bending deformation.
The cross-sectional shape cut right and left with respect to the neutral surface of bending deformation
Become asymmetric. An ink jet printer according to a fifth embodiment of the present invention
FIG. 7 is a sectional view of the elastic member of the jet recording head. Figure
7A illustrates an inkjet recording apparatus according to the present embodiment.
FIG. 7B is a cross-sectional view of the same front side.
It is. The ink jet recording head of the present embodiment
One surface of the elastic member 7 is perpendicular to the surface of the vibrator 2.
And the other surface is attached to the surface of the vibrator 2.
The feature is that it is configured to have a slope at the contacting part
Have. Also in this case, the elastic member 7 is
The cross-sectional shape cut by a plane perpendicular to the vertical axis
It becomes left-right asymmetric with respect to the neutral surface of the vertical deformation. Next, according to the sixth embodiment of the present invention,
FIG. 8 is a sectional view of the elastic member of the ink jet recording head.
You. FIG. 8A illustrates an inkjet according to the present embodiment.
FIG. 8B is a side sectional view of the recording apparatus, and FIG.
It is sectional drawing. The ink jet recording head according to the present embodiment.
The surface of one side of the elastic member 7 is opposed to the surface of the vibrator 2.
It is mounted so as to be vertical, and the other surface is
Is curvedly thicker toward the mounting part of the vibrator 2
The feature is that it is configured to change
You. Also in this case, the elastic member 7 is bent against the neutral axis of the bending deformation.
And the cross-sectional shape cut by the vertical surface
It becomes left-right asymmetric with respect to the neutral plane. An ink jet printer according to a seventh embodiment of the present invention
FIG. 9 is a sectional view of the elastic member of the jet recording head. Figure
9A shows an ink jet recording apparatus according to the present embodiment.
FIG. 9B is a cross-sectional view of the same front side.
It is. The ink jet recording head of the present embodiment
One surface of the elastic member 7 is perpendicular to the surface of the vibrator 2.
And the other surface is the thickness of the elastic member 7.
Becomes discontinuously thicker toward the mounting part of the vibrator 2.
It is characterized in that it is configured to change as follows.
Also in this case, the elastic member 7 is bent with respect to the neutral axis of the bending deformation.
The cross-sectional shape cut by a vertical surface is neutral for bending deformation
It becomes left-right asymmetric with respect to the surface. Further, according to the eighth embodiment of the present invention,
FIG. 10 is a sectional view of the elastic member of the ink jet recording head.
Shown in FIG. 10A shows an ink jet printer according to the present embodiment.
FIG. 10B is a side cross-sectional view of the jet recording apparatus, and FIG.
It is sectional drawing of a front side. Inkjet of this embodiment
In the recording head, both surfaces of the elastic member 7 are the surfaces of the vibrator 2.
Is mounted vertically to
Is characterized in that a plurality of irregularities are formed on the surface. this
Even if the bumps are close enough to touch each other,
Grooves and peaks, whether they are located in a dam or in a row
And may balance the bending of the elastic member 7.
At the start of vibration of the elastic member 7
If the structure is such that the starting direction of
You may choose any. As in this example, bending of the elastic member 7
Cross section cut by a plane perpendicular to the neutral axis of deformation
If the shape is at least partially asymmetric,
The effect of is not changed. As described above, the basis of the present invention is the following.
The bending vibration of the elastic member of the cantilever structure causes
A capillary wave is generated on the ink surface near the edge,
In the ink jet recording head that flies, the elasticity
Cut by a plane perpendicular to the neutral axis of the bending deformation of the member.
By making the cut cross section asymmetrical,
To stabilize the flight phenomena
You. That is, an elastic member having an asymmetric cross section is used.
If the operation / effect aimed at by the present invention is obtained, the elastic member
Many cross-sectional shapes are found as in the above embodiment.
You. The present invention is not limited to the above-described embodiment, but includes various
Deformation is possible. For example, the cantilever structure of the elastic member 7
Of the bending vibration near the free end of the free end
Where the width W of the vertical plane is approximately W = 2λ
May be provided. Where λ is given by
Can be λ = ｛8πσ / (ρfe ^Two )｝ ^1/3 × 10 ^Four (Μm) where σ is the ink surface tension (mN / m) ρ is the ink density (g / cm ^Three ) Fe is the excitation frequency (Hz). By doing so, two peaks in width W
Pillar waves can be generated, and then a single peak of ink is formed
The next moment this is separated and more precisely one ink drop
You will be able to fly. As described above, according to the present invention, the nozzle is
Small droplets can be ejected without using
Small droplets that meet the demand for higher resolution
Can be ejected. In particular, elastic members with a cantilever structure
Bending vibration causes the ink surface near the tip of the elastic member to
An ink jet that generates capillary waves and causes ink to fly
In a jet recording head, the direction of bending vibration of the elastic member
At least part of the cross section perpendicular to the direction is asymmetric
By doing so, it is possible to stabilize the ink flying phenomenon.
And be able to. In addition, driving at low frequency and low power
Energy efficient and use
The range of possible liquid properties also widens.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing the appearance of an ink jet recording head according to a first embodiment of the present invention. FIG. 2 is a sectional view of the inkjet recording head according to the first embodiment of the present invention. FIG. 3 is a diagram for explaining signals applied to a vibrator of the inkjet recording head according to the first embodiment of the present invention. FIG. 4 is a sectional view near an elastic member of an ink jet recording head according to a second embodiment of the present invention. FIG. 5 is a sectional view showing the vicinity of an elastic member of an ink jet recording head according to a third embodiment of the present invention. FIG. 6 is a sectional view showing the vicinity of an elastic member of an inkjet recording head according to a fourth embodiment of the present invention. FIG. 7 is a sectional view near an elastic member of an inkjet recording head according to a fifth embodiment of the present invention. FIG. 8 is a sectional view near an elastic member of an ink jet recording head according to a sixth embodiment of the present invention. FIG. 9 is a sectional view near an elastic member of an ink jet recording head according to a seventh embodiment of the present invention. FIG. 10 is a sectional view near an elastic member of an ink jet recording head according to an eighth embodiment of the present invention. FIG. 11 is an explanatory diagram of a printing apparatus according to the related art. FIG. 12 is an explanatory diagram of a printing apparatus according to the related art. FIG. 13 is a diagram illustrating a neutral axis and a neutral surface. FIG. 14 is a diagram illustrating a neutral axis and a neutral surface. FIG. 15 is a diagram illustrating a neutral axis and a neutral surface. [Description of Signs] 1 Substrate 2 Vibrator 3 Piezoelectric 4, 5 Electrode 6 Protective layer 7 Elastic member 8 Ink 9 Ink drop 91 Piezoelectric 92, 93 Electrode 94 Vibration generating mechanism 95 Sound collector 96 Ink 97 Ink free surface 98 Ink drop 99 ink reservoir

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/01

Claims (1)

(57) Claims: 1. A vibration generating means that vibrates in response to a pixel signal, and a cantilever structure that bends and vibrates in response to excitation of the vibration generating means, the beam structure, the cross-sectional shape obtained by cutting by a plane perpendicular to the neutral axis of bending deformation, and an elastic member made asymmetrical with respect to the neutral plane of the bending deformation, the bending vibration of the elastic member, the elastic Near the tip of the member
An ink jet recording head, wherein a capillary wave is generated on the surface of ink next to the ink, and the ink is caused to fly and adhere to a recording medium.