JP3486080B2 - Ink jet recording device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
Recording an image by flying over a recording medium
Related to the ink jet recording device, especially radiated by the piezoelectric element
Ink droplets are ejected by the pressure of the ultrasonic beam
Regarding an inkjet recording device that flies over a recording medium
You. [0002] 2. Description of the Related Art Ink droplets are formed into droplets and fly onto a recording medium.
Apparatus for forming image points and recording images by moving
Has been put to practical use as an inkjet printer.
This inkjet printer is noisy compared to other recording methods.
Low noise, no need for processing such as development or fixing
It has advantages and is attracting attention as a plain paper recording technology. Present
Many inkjet printer methods have been proposed to date
In particular, Japanese Patent Publication No. 56-9429 and
Heating element disclosed in Japanese Patent Publication No. 61-59911
Ink droplets fly with the pressure of steam generated by the heat of
And disclosed in Japanese Patent Publication No. 53-12138.
Pressure drop due to the displacement of the piezoelectric body
Is a typical method. [0003] However, in these methods, evaporation or volatilization of a solvent is performed.
It is easy for ink concentration to occur locally by firing,
Because the individual nozzle corresponding to each resolution is thin,
There is a problem that the nozzle is easily clogged. Special
In the method using the pressure of steam, thermal
Or the adhesion of insolubles caused by chemical reactions, etc.
In the method using the pressure due to the displacement of the piezoelectric body,
Complex structures in the flow path, etc. may cause more clogging
I'm sick. Dozens to hundreds of nozzles are used
Low frequency of clogging with serial scanning heads
Lines that can be reduced, but require thousands of nozzles.
Probable clogging with the scanning head
Occurs, which is a major problem in terms of reliability. Further
However, these methods are not suitable for improving resolution.
There are also disadvantages. To overcome these drawbacks, the pressure of the thin film
Ink liquid using the pressure of the ultrasonic beam generated from the electric body
Those who use ultrasonic waves to fly ink droplets from the surface
Equations have been proposed (IBM TDB, vol. 16,
No. 4,1168 (1973-10), JP-A-63
JP-A-162253, JP-A-63-166548,
JP-A-63-212157, JP-A-2-1844
43, etc.). This method uses the noise for each individual dot.
So-called nozzles that do not require partitions between ink channels and ink channels
Because of the headless system, it is
Problems like clogging and recovery from
Absent. Also, this method uses very small diameter ink droplets.
Can fly stably, so that high resolution
Are suitable. However, these methods using ultrasonic waves
Low flying efficiency of ink droplets, thus improving image recording speed
There is a problem that it can not be done. Further, a conventional ultrasonic ink jet method
In a typical head structure of a recording apparatus, an ultrasonic focusing
The acoustic lens, especially the Fresnel lens, that constitutes the means
As a support member for the ink liquid holding chamber that contains and holds ink liquid.
To provide mechanical strength
Is sufficiently thicker than the piezoelectric material,
Have the same or greater thickness. like this
In a simple structure, the ultrasonic waves radiated from the piezoelectric element
The lens is so thick that it propagates
Attenuation and scattering occur, and ultrasonic waves are efficiently
Difficult to radiate inside. In particular, flying small diameter ink droplets
Smell when emitting high frequency ultrasonic waves to make it fly
The effect of ultrasonic attenuation and scattering in the Fresnel lens
Is significantly larger. Also, random repulsion generated inside the Fresnel lens
Ultrasonic waves enter from parts other than the effective lens
There is also a problem that the liquid is irradiated into the solution. Solve this
In order to decide, Fresnel lens other than the effective lens part
Do not touch the ink liquid directly with the side walls of the ink chamber, etc.
Covering is being done. However, the effective
A certain obstacle such as an ink chamber near the lens
And the ultrasonic wave radiated into the ink liquid is the ink liquid / obstacle
Is strongly reflected at the interface of the
Focusing is disturbed. As described above, in the conventional system and structure,
It is difficult to fly ink droplets efficiently.
Need to apply extra voltage to the piezoelectric element.
In addition, it is necessary to lengthen the voltage application time. As a result,
Increases power consumption and increases image recording speed
There is also a problem that it is not possible. [0008] SUMMARY OF THE INVENTION The present invention has been made in view of the above problems.
Is to solve the problem.
Power consumption to improve the efficiency of ink droplet flight,
The time from when the element is driven until the ink droplet flies
The challenge is to shorten the recording speed and increase the recording speed.
You. [0009] SUMMARY OF THE INVENTION The present invention provides,IInk solution
Holding ink liquid holding chamber, piezoelectric body and its pressure
A pair of first and second pairs disposed opposite each other on both sides of the electric body;
Including a plurality of piezoelectric elements consisting of electrodes, the ink liquid and
Ultrasonic generation means acoustically connected, and the ultrasonic generation
Driving means for driving the means, and
The ultrasonic waves generated by the ultrasonic wave generating means.
Ultrasonic focusing lens unit for focusing near the liquid surface of the ink liquid
Ink jet recording device having an ultrasonic focusing means including a material
In the recording apparatus, a first electrode of the pair of electrodes
Indicates that each end in the direction orthogonal to the
From each corresponding end of the second electrode, the thickness of the piezoelectric element is
In the piezoelectric surface area excluding the length exceeding the
And an effective lens aperture of the ultrasonic focusing lens member
Diameter W_LAnd the thickness T of the piezoelectric body_PAnd the arrangement of the piezoelectric element.
Overlap of the pair of electrodes in a direction perpendicular to the column direction
Width W_EIs the following formula W_L≧ W_E+ 2T_P                (1) Characterized by satisfying the relationship represented by:
The present invention provides a cut recording device. [0010] In the present invention, the ultrasonic focusing lens section
Preferably, the material includes a Fresnel lens. Also book
In the invention, the ultrasonic focusing lens member may be an acoustic
It is desirable to also have a function as a chining layer. The present inventors have proposed that the radiation pressure of the ultrasonic beam
Ink droplets from the ink surface and fly onto the
Ink jet recording device that records images by flying
High recording speed that could not be achieved with the conventional method
Multiple piezoelectric elements are specified for speed and higher resolution.
And a part of the piezoelectric element group (drive element group)
Is driven by giving a predetermined phase difference to the
Focus the ultrasonic beam near the surface and fly the ink droplets
Drive means for moving the drive element group in a predetermined direction.
A) An inkjet recording device equipped with an electronic scanning unit
is suggesting. Further, the above-mentioned conventional ink jet recording apparatus
In the lens that occurs due to the thick acoustic lens in
To reduce the flight efficiency due to attenuation and scattering of ultrasonic waves.
In order to separate the support function from the acoustic lens,
A structure in which a support member is provided on the back of the piezoelectric element separately from the lens
Has been proposed. In this case, acoustic lenses, especially Fresnel
The lens does not need to function as a support member.
Therefore, the thickness is the minimum necessary for ultrasonic focusing.
Thickness equivalent to the thickness of the piezoelectric material, sufficient compared to the depth of the ink liquid
A thin thickness is sufficient. This allows the acoustic lens
Ultrasonic attenuation and scattering at the site should be negligible
To improve the flight efficiency of ink droplets and record
The speed can be increased. Ultrasonic focusing means
When using a Fresnel lens for
(2n + 1) of the wavelength of the ultrasonic wave in the Fresnel lens, respectively
/ 4 times (n is an integer of 0 or more)
And acoustic impedance of piezoelectric material as Fresnel lens material
Acoustic impedance close to the square root of the product of
The use of materials with low
Make the lens also function as an acoustic matching layer
Can be This reduces the reflection of ultrasonic waves at the interface
It is possible to improve the flight efficiency. However, it faces the piezoelectric body over its entire width.
An electrode is formed, and an effective lens aperture with the same width as the piezoelectric
Conventional structure for forming an ultrasonic focusing lens member having a diameter
Then, when processing the piezoelectric body into a predetermined shape, the cutting part of the piezoelectric body
It is said that characteristic deterioration is likely to occur due to depolarization etc. in the vicinity
That was found. Also, in such a structure, the piezoelectric
It is easy to cause a short circuit between the opposite electrode positions at the end of the body
I understood that. Therefore, the present inventors have proposed the width of the piezoelectric body and
Opposing current to effective lens aperture of ultrasonic focusing lens member
After extensive research on the effects of the width of the poles, etc.,
One of the electrodes (the first electrode) is arranged with the piezoelectric element.
Each end in the direction (sub-scanning direction) perpendicular to the column direction is
From each corresponding end of the other electrode (second electrode)
Exists in the piezoelectric surface area less than the length corresponding to the thickness.
And each end of the second electrode in the sub-scanning direction.
In the area corresponding to the first and second, the first and second
By providing sound insulation members of
Characteristics such as the main beam position (focal position
Ultrasonic focusing due to strong side lobes generated in places other than
To reduce the drop efficiency of ink droplets
I found something that could be prevented. In this case, the first electrode
Can be formed shorter than the second electrode.
Or it can be formed to the same length as the second electrode
You. Further, the present inventors have made the first electrode
Are each corresponding end of the second electrode in the sub-scanning direction.
The piezoelectric body surface exceeds the length corresponding to the thickness of the piezoelectric element from
Depolarization can also occur by providing
It has been found that deterioration of characteristics caused by the above-mentioned factors can be prevented.
In this case, the effective lens of the ultrasonic focusing lens member
Caliber W_L And the thickness T of the piezoelectric body_P And the weight of the pair of opposed electrodes
Become width W_E Is the following formula (1): W_L ≧ W_E + 2T_P         (1) When the relationship indicated by
Not only can prevent the
Further finding that the occurrence of short circuits between poles can be suppressed
Was. In this case, the width of the ultrasonic focusing lens member is
Can be equal to the width of the effective lens area.
It can be equal to the width of the piezoelectric body. The ultrasonic focusing lens is a Fresnel lens.
, The position of each groove from its center is
As is known in the field, the following equation (2) or equation (3)
Position corresponding to the radius r (a) of the Fresnel zone expressed by
Formed. [0018]   r (a) = [(2a-1) λ_i / 2 × ΔF + (2a-1) λ_i / 8｝]^1/2   (2) r (a) = (aλ_i F)^1/2     (3) In equations (2) and (3), λ_i Is in the ink liquid
, F is the focal length (depth of ink liquid), a
Is an integer of 1 or more. In the present invention, the ultrasonic focusing lens is a flexible lens.
In the case of a flannel lens, its effective lens aperture is
In the above formula (2) or (3), which corresponds to the number n of grooves formed,
This corresponds to twice the defined radius r (n). [0020] BRIEF DESCRIPTION OF THE DRAWINGS FIG.
This will be described with reference to FIG. Throughout the drawings, the same parts
Number. FIG. 1 shows an embodiment of the present invention.
FIG. 2 is a perspective view of a recording head unit of the inkjet recording apparatus.
You. FIG. 2 shows a head of the ink jet recording apparatus shown in FIG.
Including the piezoelectric element and the ultrasonic focusing lens
FIG. 4 is an enlarged cross-sectional view showing a region of the occupied area. Ink jet recording shown in FIGS. 1 and 2
The head of the device is a flat plate pressure
An electric body 12 is provided on the support member 11. The piezoelectric body 12 is
Depending on the frequency of the sound wave and the size of the element, lead titanate (P
T), ceramics such as zircon and lead titanate (PZT)
Material, copolymerization of vinylidene fluoride and ethylene trifluoride
Polymer material such as body, single crystal material such as lithium niobate,
Can be formed of piezoelectric semiconductor materials such as zinc oxide
You. The support member 11 is formed of a material such as glass.
be able to. The lower surface of the piezoelectric body 12 has
A number of individual electrodes 13 are each formed. Piezoelectric
The body 12 is functionally provided with a plurality of
It is divided into piezoelectric elements. On the other hand, on the upper surface of the piezoelectric body 12,
An integral common electrode 14 is formed. These electrodes 13
And 14 are titanium, nickel, aluminum, copper,
Form a thin film of metal such as gold by evaporation or sputtering
can do. Alternatively, these electrodes 13 and 1
4 is a mixture of glass frit mixed with silver paste.
Printing by the clean printing method and printing it
Therefore, it can also be formed. Common electrode with individual electrode 13
The corresponding part of the pole 14 constitutes each counter electrode. A piezoelectric member is provided at one end of the support member 11.
At the same interval as the individual electrodes 13 formed on the lower surface of the body 12,
A plurality of array electrodes 15 are formed.
11 and each individual electrode on the lower surface of the piezoelectric body 12
The electrode 13 is aligned with the conductive adhesive and crimped.
And are electrically connected. Array on support member 11
The electrode 15 is driven by a driving circuit disposed on the end of the support member 11.
Path 16 by a bonding wire 17
The common electrode 14 formed on the upper surface of the conductor 12 is also not shown.
It is connected to the drive circuit 16 by a suitable wiring. The entire surface of the piezoelectric body 12 is covered via the common electrode 14.
The ultrasonic focusing acoustic lens member 18 is provided as shown in FIG.
You. The lens member 18 has a symmetrical position from its center.
Each pair has a predetermined pitch based on Fresnel's ring theory.
1 and 2, a plurality of grooves (four grooves 1 in FIGS. 1 and 2).
8a to 18d, 18a and 18b, 18c and 18d
Are formed symmetrically), but each individual electrode 13
In the arrangement direction of the divided piezoelectric elements (corresponding to the main scanning direction)
They are formed in parallel. The depth of each groove is the top and bottom of the groove
To shift the phase of the ultrasonic wave emitted from
The wavelength of the ultrasonic wave in the lens member 18 (2 m
+1) / 4 (m is an integer of 0 or more)
ing. The grooves are for the arrangement of piezoelectric elements separated by individual electrodes.
It is formed parallel to the column direction (corresponding to the main scanning direction). In the present invention, the Fresnel lens member
18 is for acoustic matching between the piezoelectric element and the ink liquid.
Function as an acoustic matching layer for
New To achieve this, the Fresnel lens member must be
-Dance Z_m Is the acoustic impedance Z of the piezoelectric body_p And Inn
Acoustic impedance Z_i And the square root of the product (Z_m=
(Z_p × Z_i )^1/2 Formed of a material having a value close to
It is desirable. Such materials include epoxy trees
Polymer materials such as fats and polyimides, or their polymers
Fiber or to adjust the acoustic impedance to the material
A mixture of powders such as alumina or tungsten
Can be exemplified. On the supporting member 11, the piezoelectric element 1
2. Store the Fresnel lens member 18 and the ink liquid 20
An ink liquid holding chamber 19 is provided. This ink liquid
The side wall surrounding the ink liquid 20 is made of Fresnellen.
Angled from both ends of the
The upper part is opened by forming a slit 19a.
You. Now, as best shown in FIG.
In addition, the individual electrodes 13 formed on the lower surface of the piezoelectric
It has a length W1 equivalent to the width of the electric body 12. But
The common electrode 14 formed on the upper surface of the piezoelectric body 12
In the illustrated example, the length is shorter than the piezoelectric body 12 (length W2),
It is formed only in the central region except for both ends of the body 12
I have. Therefore, the piezoelectric body 12 functioning as each piezoelectric element
The portion is only a region corresponding to the common electrode 14. this
In each case, each end of the piezoelectric body exposed by the common electrode 14
The lengths W3 and W4 of the surface area are determined by the thickness of the piezoelectric body 12.
It is set to be less than the corresponding length.That is, the common
The pole 14 is arranged in a direction orthogonal to the direction in which the piezoelectric elements are arranged.
Each end of the piezoelectric element is separated from the corresponding end of the individual electrode 13.
Piezoelectric surface area excluding the length less than the length corresponding to the thickness
Exists in the area.And corresponding to both ends of the individual electrodePressure
Electric body surfaceIn the area, the sound insulating members 21a and
And 21b are provided respectively. In the example shown in FIG.
The sound insulation members 21a and 21b
In addition to covering the above-mentioned exposed area, the end of the common electrode 14
It is provided over. Such a sound insulating member 21
a and 21b are materials different from the lens member 18;
Thus, a material capable of shielding ultrasonic waves radiated from the piezoelectric body 12
Material, for example, a silicone resin. With this configuration, the common power
Oscillation can also occur from the piezoelectric portion corresponding to the periphery of the pole 14
Can be ultrasonically shielded, thus generating side lobes
To suppress ink droplets and make ink droplets fly efficiently
it can. Moreover, the sound insulation members 21a and 21b are provided.
Whether the length of the piezoelectric body region is equal to or less than the thickness of the piezoelectric body 12
Therefore, the lens member 18 can be provided widely, and an effective super
Sound waves can be further utilized. Also common
The region of the piezoelectric body 12 beyond the electrode 14 is a sound insulating member.
21a and 21b, the common electrode
A short circuit between 14 and the individual electrode 13 is also prevented. Next, in the above ink jet recording apparatus,
Examples of a method of focusing ultrasonic waves and a method of driving a piezoelectric element
explain. In the arrangement direction (main scanning direction) of the piezoelectric elements 11
The focusing method of the ultrasonic waves in the
Part of the piezoelectric element composed of the piezoelectric body 12 operated in a
Predetermined delay time for piezoelectric element group (simultaneous driving element group)
And drive them simultaneously, then each piezoelectric element
By controlling the phase of the ultrasonic waves radiated from the
So that the intensity of the ultrasound locally increases locally,
Operate to focus. Specifically, simultaneous drive elements
The central group has the longest lag time, moving outwards
The delay time is gradually shortened. Meanwhile, the array
Direction perpendicular to the arrangement direction of the piezoelectric elements (the present invention)
In the sub-scanning direction)
The method is based on an acoustic lens, here a Fresnel lens 18.
Do it. By focusing the ultrasonic waves from two directions,
Ink drops from any position on the ink surface with ultrasonic pressure
Is ejected and flies. The flying position of the ink droplet
By scanning the moving piezoelectric elements electronically,
It is possible to In addition, pressures arranged in an array
Providing a plurality of the simultaneously driving element groups among the electric elements
Allows multiple ink droplets to fly at the same time
You. The other is based on the Fresnel zone theory,
Group the number of simultaneous driving elements into two types and drive one
The phase to be shifted by π with respect to the other
That is. This is called Fresnel driving.
You. The ultrasonic convergence degree in the sub-scanning direction is high.
In this case, the main scanning direction only drives a plurality of elements simultaneously,
Ink droplets fly without delay and focusing
Therefore, there is no need to provide a delay time. FIG. 3 shows a second embodiment of the present invention.
And the lens member 18 connects the common electrode 14
FIG. 1 and FIG.
The same as the head part of the ink jet recording apparatus shown in FIG.
FIG. 3 is a perspective view of a head unit. Also in this case the piezoelectric
12 so as to cover the exposed surface of
1b is provided. FIG. 4 shows that the common electrode 14 is the length of the individual electrode 13.
1 and 2 except that it is formed with a width equivalent to that of FIG.
A head similar to the head of the inkjet recording device
It is shown. In this case, the sound insulating members 21a, 21b
Is formed so as to cover at least the end of the common electrode 14.
Have been. Thus, the common electrode 14 is
By forming it with the same width as the length, the ultrasonic oscillation area
The area can be expanded. It should be noted that, in FIGS.
At least one of the ink liquid holding chambers 1a and 21b.
It is also possible to configure the side wall surrounding the ink liquid 20 of FIG.
You. FIG. 5 shows that the sound insulation members 21a and 21b are
The same material as above, but the thickness is
Also have a large thickness (for example, a thickness greater than 60 μm).
1 and FIG. 2 except that
Similar to the head part of the inkjet recording device shown
It shows a head section. FIG. 3 shows the configuration in FIG.
The lens members of the arrangement shown have the common electrode at both ends.
It may be formed beyond. FIG. 6 shows the sound insulating member 21.
a and 21b were formed in the form shown in FIG.
4 similar to the head of the ink jet recording apparatus shown in FIG.
FIG. FIG. 7 shows the sound insulating members 21a and 21b
The surface of the lens member is roughened (reference numerals 211a and 2a, respectively).
11b) except for the configuration shown in FIG.
Head similar to the head part of the inkjet recording apparatus shown
It shows a part. FIG. 3 shows the configuration in FIG.
The lens members of the arrangement shown have the common electrode at both ends.
It may be formed beyond. FIG. 8 shows the sound insulating member 21.
a and 21b are the surface of the lens member as in the case of FIG.
Is roughened (represented by reference numerals 211a and 211b, respectively)
The ink jet recording apparatus shown in FIG.
5 shows a head unit similar to the head unit of the device. FIGS. 9 and 10 show still another embodiment of the present invention.
An inkjet recording apparatus according to an embodiment of the present invention is shown,
FIG. 10 shows a piezoelectric element of the ink jet recording apparatus shown in FIG.
Enlarge the area including the element and the ultrasonic focusing lens member.
FIG. 1 and FIG. 2,
The same reference numerals are used, and details thereof are shown in FIGS.
This is as described above. In this recording apparatus, FIG.
As shown, the length W of the common electrode 14 is_EIs an individual
Length W of separate electrode 13₁Shorter than this common electrode
The length W3 'of the exposed end surface area of the piezoelectric body 12 and
And W4 'are longer than the length corresponding to the thickness of the piezoelectric body.
HavingThat is, the common electrode 14 is provided with a piezoelectric element arrangement.
Each end in a direction orthogonal to the column direction is a pair of individual electrodes 13.
Exceed the length corresponding to the thickness of the piezoelectric element from each corresponding end
It exists in the piezoelectric body surface area excluding the length.in this way
Then, without providing the sound insulating member, FIGS.
The same effect as the inkjet recording device described with respect to
Obtainable. Further, in the examples shown in FIGS. 9 and 10,
The lens members 18 of the individual electrodes are added to the grooves 18a to 18d.
Also, Fresnel's
Grooves 18e to 18j are formed based on the ring zone theory,
Effective lens area 18 of the closing member 18_eff Width (effective lens
Aperture) is the sub-scanning direction of the individual electrode 13 and the common electrode 14
(In this case, the sub-scanning method of the common electrode 14)
Direction width) by a predetermined degree. More specifically, as shown in FIG.
1 and FIG.
The lens member 18 is formed as described in FIG.
And formed as described in FIG.
The groove extends beyond the area of the common electrode 14 as described above.
As a result, the effective lens aperture W of the lens member 18 is obtained.
_L Is the width W of the common electrode 14 in the sub-scanning direction._E Greater than
Have been. In this case, as the effective lens aperture increases,
The degree is the thickness T of the piezoelectric body 12._P Also defined by
Turned out to be important. That is, the effective lens aperture
Diameter W_E Is the above formula (1): W_L ≧ W_E + 2T_P It is preferable to satisfy the relationship represented by This relationship is based on the pair formed on both surfaces of the piezoelectric body.
Effectiveness greater than the overlap width of the counter electrode in the sub-scanning direction
If Fresnel lens is formed with aperture
The effective lens area formed on the lens member is
Is formed larger than the overlap width of the counter electrode.
Stipulates how large it should be.
I can. The effective lens aperture has such a relationship.
And short-circuit prevention as described with reference to FIGS.
Stop and side lobe generation are more effectively achieved.
It is. FIG. 11 shows the lens member 18 as a sub-run of the common electrode 14.
The sub-scanning of the piezoelectric body 12 is larger than the width in the scanning direction.
Smaller than the width in the direction
9 and FIG. 10 except that the number of
Head similar to the head part of the inkjet recording apparatus shown
It is a schematic sectional drawing which shows a part. Also in this case, FIG.
The same effect as that shown in FIG. 4 is obtained. The embodiment of the present invention will be described with reference to the drawings.
Although described, the present invention is not limited to these.
No. For example, the length (width) of the individual electrode 13 is
The width in the sub-scanning direction is the same, and the width of the common electrode 14 is
If the width of the piezoelectric body 12 is smaller than the width in the sub-scanning direction,
In the above description, the individual electrodes 13 and the common electrodes 14
The same effect can be obtained even if the width relationship is reversed.
Needless to say. [0045] The present invention will be further described below with reference to examples. Examples 1-2 In the present embodiment, the ink jet printer having the structure shown in FIGS.
A jet recording device was prepared. The thickness of the piezoelectric body 12 is about 0.5 mm.
Using a lead titanate-based piezoelectric ceramic with a relative dielectric constant of 200
Was. Ti / A is formed on both surfaces of the piezoelectric body by sputtering.
u electrode layers each having a thickness of 0.05 μm and a thickness of 0.05 μm.
Formed to be 2 μm and apply an electric field of 3 kV / mm
Then, the polarization treatment of the piezoelectric body 12 was performed. Then, the piezoelectric body 1
Patterning the electrode layer on one side of
The width 60 of one piezoelectric element is μm, between individual electrodes.
The gap becomes 25 μm (the arrangement pitch of individual electrodes is 85 μm)
The individual electrode 13 was formed as described above. In addition, the auxiliary
The width in the scanning direction was 5 mm. On the other hand, Ti / A
The array electrode 15 of u was formed. Then, on the piezoelectric body 11
Of the individual electrodes 13 and the array electrodes 15 on the support member 11.
In a state where they are placed side by side, glue them with conductive epoxy resin.
Pressurization was performed so that the electrodes would conduct. Next, the piezoelectric body was polished to a thickness of 50 μm.
Then, the common electrode 14 made of aluminum is sputtered.
Thus, the thickness was formed to 0.3 μm. At this time,
The length of the electrode in the direction was 2.0 mm. Next, Fresnel which also serves as an acoustic matching layer
Epoxy resin and alumina are used to make the lens 18.
The speed of sound is 3 × 10 with the powder mixture.^Three It will be near m / s
2.20 × 10^Three kg / m^Three ,
Sound speed 2.95 × 10^Three An m / s mixture was obtained. This
Coated on the upper surface of the through electrode 14 and cured, the thickness is 45 μm
It was polished to become. After that, the focal length became 2.5 mm
Main scanning of a half-wavelength groove (approximately 30 μm)
The Fresnel lens 18 was formed parallel to the direction.
The width of the groove forming area (lens diameter) is the width of the common electrode (opposing
0.1mm wider than 2.0mm)
2.1mm (Example 1) and 0.2mm wider
It was 2.2 mm (Example 2). And ultrasonic emission
So that the distance between the firing surface and the ink liquid level is approximately 2.5 mm
An ink liquid holding chamber 19 is provided in the
The drive circuit 16 is installed in the ink jet printer according to the present invention.
We completed the recording system. Comparative Examples 1-2 Each lens aperture is 2.0 mm (same as the width of the piezoelectric body:
Except for Comparative Example 1) or 2.05 mm (Comparative Example 2)
Shows two types of ink jet recording in the same manner as in Example 1.
The device was made. The samples 4 prepared in Examples 1 and 2 and Comparative Examples 1 and 2
An ink droplet flight experiment was performed using two recording devices. I
In the flight experiment of ink droplets, the driving frequency (50 MHz) and
And drive voltage (20V) are set to the same
The application time of the dynamic burst signal is used as the evaluation criterion for the flight efficiency.
Was. The minimum required for obtaining a stable ink droplet flight
FIG. 12 shows the application time of the boost. In FIG. 12, point a
Represents the result of Example 1, point b represents the result of Example 2, and point c represents the result of Example 2.
Indicates the result of Comparative Example 1, and point d indicates the result of Comparative Example 2. As shown in FIG. 12, the overlapping width of the counter electrode
If the width of the effective lens area is larger than
By satisfying the relationship of (1) (Example 1 and
2) less berth than at other times (Comparative Example 2)
In this way, stable ink droplet flight is possible with the
It can be seen that constant ink droplet flight can be achieved with high efficiency.
Call The overlap width of the counter electrode and the width of the effective lens area are the same
(Comparative Example 1), it is larger than the overlapping width of the counter electrode.
When the width of the effective lens area is increased (Examples 1 and 2
The flying efficiency of ink droplets is much lower than in Comparative Example 2)
I understand that. [0053] As described above, according to the present invention, the super
Suppresses the generation of sound waves that interfere with sound wave focusing, making it more effective
Ink droplets can be ejected to the recording speed
Inkjet printing that can achieve high speed and low power consumption
A recording device is provided. Inkjet recording device of the present invention
Then, a short circuit between the opposing electrodes can be prevented.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a head section of an ink jet recording apparatus according to the present invention. FIG. 2 is an enlarged schematic cross-sectional view of a region including a piezoelectric body and an ultrasonic focusing lens member of a head unit of the ink jet recording apparatus shown in FIG. FIG. 3 is a perspective view of a head section of another inkjet recording apparatus according to the present invention. FIG. 4 is a perspective view of a head section of another inkjet recording apparatus according to the present invention. FIG. 5 is a perspective view of a head section of another inkjet recording apparatus according to the present invention. FIG. 6 is a perspective view of a head section of another inkjet recording apparatus according to the present invention. FIG. 7 is a perspective view of a head section of another inkjet recording apparatus according to the present invention. FIG. 8 is a perspective view of a head section of another ink jet recording apparatus according to the present invention. FIG. 9 is a perspective view of a head section of still another inkjet recording apparatus according to the present invention. 10 is an enlarged schematic cross-sectional view of a region including a piezoelectric body and an ultrasonic focusing lens member of a head unit of the ink jet recording apparatus shown in FIG. FIG. 11 is a schematic cross-sectional view of a head section of still another inkjet recording apparatus according to the present invention. FIG. 12 is a graph showing the results of an example according to the present invention together with the results of a comparative example. DESCRIPTION OF SYMBOLS 11 ... Support member 12 ... Piezoelectric element 13 ... Individual electrode 14 ... Common electrode 15 ... Array electrode 16 ... Drive circuit 18 ... Ultrasonic focusing lens member 19 ... Ink liquid holding chamber 19a ... Slit 20 ... Ink liquid

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kenichi Mori 1st Toshiba-cho, Komukai, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center (72) Inventor Hitoshi Yagi Toshiba-cho, Koyuki-ku, Kawasaki-shi, Kanagawa No. 1 Toshiba R & D Center Co., Ltd. (72) Inventor Noriko Yamamoto No. 1 Komukai Toshiba Town, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Toshiba R & D Center Co., Ltd. (56) References JP-A-7-137250 (JP, A) JP-A-8-238765 (JP, A) JP-A-9-94957 (JP, A) JP-A-63-166547 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) B41J 2/015 B41J 2/045 B41J 2/055

Claims (1)

(57) Claims: 1. An ink liquid holding chamber for holding an ink liquid, a piezoelectric body, and a pair of first and second electrodes disposed opposite to both surfaces of the piezoelectric body, respectively. Including a plurality of piezoelectric elements consisting of, ultrasonic generating means acoustically connected to the ink liquid, driving means for driving the ultrasonic generating means,
An ink jet recording apparatus comprising: an ultrasonic focusing unit including an ultrasonic focusing lens member formed on the ultrasonic generating unit and focusing an ultrasonic wave generated by the ultrasonic generating unit near a surface of the ink liquid. In the pair of electrodes, the first electrode has a length corresponding to a thickness of the piezoelectric element from a corresponding end of the second electrode at each end in a direction orthogonal to the arrangement direction of the piezoelectric elements. present on the piezoelectric surface area excluding the length components outside, and said an effective lens aperture W _L of the ultrasound focusing lens member, and the thickness T _P of the piezoelectric body, a direction orthogonal to the array direction of the piezoelectric element overlapping width W _E of the pair of electrodes in the ink jet recording apparatus that satisfies the relationship represented by the following formula _{W L ≧ W E + 2T P} (1).