JP2001158099A - Ink-jet recording head and ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink-jet recording head and an ink-jet recording apparatus in which of resolution recording dots can be increased, a discharge velocity and a discharge direction of ink are stable, images can be recorded at a high speed, and a drop diameter of ink drops can be changed by one discharge operation with problems because of nozzles being eliminated. SOLUTION: A laser light-generating device 24 and a condenser lens 26 are arranged below an ink-holding member 12. A bottom part of the ink-holding member 12 is constituted of a laser light guide body 230 having a thick part 230A, a middle part 230D and a thin part 230B. Bubbles 38 generated to a boundary part between the ink 18 and the laser light guide body 230 by a laser light 28 expand, thereby generating impulse waves 32 in the ink 18. Ink drops 16 are consequently discharged from a gas-liquid interface 34 to a paper P. A thickness T of an ink layer is changed by the laser light guide body 230 and also the drop diameter L of ink drops 16 can be changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for ejecting ink droplets in accordance with image information and recording an image on a recording medium surface, and an ink jet recording apparatus provided with the ink jet recording head.

[0002]

2. Description of the Related Art Various types of ink jet recording heads for ejecting ink droplets in accordance with image information and performing printing on the surface of a recording medium have been proposed. The main components are a so-called drop-on-demand (DOD) type ink jet recording head that discharges ink droplets from nozzles according to image information, and a continuous flow type ink jet recording head that continuously discharges ink from nozzles. There is.

[0003] Typical drop-on-demand type ink jet recording heads include, for example, one using a piezoelectric element, ie, a piezoelectric element (piezo-vibrator type);
There is a type that utilizes heat generated by a heating element (thermal type).

The piezo oscillator type applies a pulse voltage to a piezoelectric element provided in an ink chamber and deforms the piezoelectric element to generate a pressure wave in the ink chamber. Is formed.

On the other hand, in the thermal type, the ink is heated by a heating mechanism provided in the ink chamber, bubbles are generated by instantaneously boiling, and the ink is ejected from a nozzle by the pressure to form dots on a recording medium. Form.

In addition, the thermal type includes a so-called optical addressing type recording head. This is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 24197 and Japanese Patent Application Laid-Open No. 55-132282, light energy such as a laser beam or a light emitting element is irradiated on ink to give thermal energy to generate bubbles, which are generated at that time. Ink is ejected from the nozzle by the action of the pressure wave.

In this method, since the generated pressure does not become sufficiently high, the discharge speed of the ink droplet is 5 to 10 m at most.
/ S, there is a problem that the ejection direction becomes unstable, and the stability of the landing position on the recording medium surface becomes poor due to air resistance or the like.

On the other hand, a continuous-flow type ink jet recording head applies pressure to ink to continuously discharge ink from nozzles, and at the same time, applies vibrations by a piezo vibrator or the like to form droplets of a discharged ink column. Further, image recording is performed by selectively charging and deflecting the droplets.

In an ink jet recording head using these ink ejection principles, in order to increase the recording resolution, the arrangement of nozzles is increased, and the diameter of the nozzle is reduced in accordance with the resolution to discharge minute ink droplets. Although it is necessary, there is a problem that the nozzle cannot easily be clogged by reducing the nozzle diameter, so that the density of the head cannot be increased and the resolution cannot be increased.

Also, when the ink flow path of the nozzle becomes narrower with the increase in density, the flow path resistance received by the ink increases,
There is a problem that sufficient discharge performance cannot be obtained. Further, it is necessary to supply ink from the ink storage device to the nozzles using an ink supply unit. However, in the conventional ink jet recording head, refilling of the nozzles with ink is rate-limiting due to the large flow resistance of the nozzles. As a result, the ink supply speed is limited by the flow path resistance, and as a result, there is a problem that the image recording speed is also reduced.

In addition, by reducing the diameter of the nozzle, clogging due to entry of foreign matter into the nozzle and drying of the ink is liable to occur, and the ink ejection direction becomes unstable due to the adhesion of the residue around the nozzle. As a result, defects in the image quality on the recording medium occur, and small bubbles of about the nozzle diameter are generated due to the vaporization of oxygen dissolved in the ink or the vibration of the ink. There was a problem.

Therefore, in a conventional ink jet recording head, a vacuum operation for sucking ink from nozzles,
A maintenance operation such as a wiping operation for removing residues and foreign matters on the nozzle surface is indispensable, and the interruption of the image recording operation thereby hinders an improvement in the image recording speed.

In order to solve such problems of the ink jet recording head having a nozzle, a nozzleless ink jet recording head has been proposed. Some nozzleless inkjet recording heads use acoustic waves.

[0014] Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent Application Publication No. 200199, there is an apparatus in which radiation pressure of a sound wave is focused on an ink liquid surface, and the energy is used to eject ink droplets from the ink liquid surface. As a problem of the method using sound waves, an acoustic radiator is necessary to generate sound waves, and it is difficult to increase the density of ink ejection points due to its low degree of freedom in shape. In addition, since a device for concentrating the discharge energy at the ink discharge position is required for each ink discharge position, the device is increased in size and cost, and the number of ink droplets that can be discharged from one recording head cannot be increased. As a result, there is a problem that the address speed and the image recording speed are reduced.

In an ink jet recording apparatus constituted by an ink jet recording head capable of discharging minute ink droplets, when an area having a size larger than the drop diameter is painted with the same color, if the area is large, the ink droplets may be removed. It has been proposed that a large drop size is created by superimposing a plurality of ink droplets on a recording medium or by colliding another ink droplet while the ink droplet is flying to record an image.

However, in such a conventional apparatus, the ejection operation must be repeated many times in order to fill a wide area, so that there is a problem that the image recording speed is reduced.

[0017]

In consideration of the above facts, the present invention has no problems caused by nozzles, enables high resolution of recording dots, has a stable ink discharge speed and discharge direction, and has a high speed. It is an object of the present invention to provide an ink jet recording head and an ink jet recording apparatus which can record an image with a single ink jet and can change a drop diameter of an ink droplet by a single ejection operation.

[0018]

According to the first aspect of the present invention, there is provided an ink holding member which holds ink and has an ink discharge port formed by opening at least a part of a portion facing a recording medium. Bubble generating means for irradiating laser light to the ink held by the ink holding member and generating a shock wave propagating at a supersonic speed in this ink so that ink droplets corresponding to image information are ejected from the ink ejection ports. And a distance changing means for changing a distance between a laser beam irradiation position from the bubble generating means and a gas-liquid interface of the ink held by the ink holding member.

In this ink jet recording head, the ink held by the ink holding member is irradiated with laser light corresponding to the image information from the bubble generating means to generate bubbles. When the bubble generates a shock wave in the ink and further propagates through the ink to reach the gas-liquid interface, the difference in shock impedance between the gas phase and the liquid phase causes the ink droplet corresponding to the image information to move in the gas phase. Is discharged to

As described above, since a shock wave propagating at supersonic speed is generated in ink to eject ink droplets, a nozzle like a conventional ink jet recording head becomes unnecessary.
For this reason, even if the ink ejection positions are arranged at a high density, nozzle clogging and ejection failure caused by this clogging,
Inconveniences such as a delay in the ink supply speed and the image recording speed due to the high flow path resistance of the nozzle do not occur. In addition, since a nozzle maintenance operation (a vacuum operation, a wiping operation, and the like) is not required, image recording is not interrupted in the middle. In addition, compared to the conventional laser addressing type bubble jet recording head,
Since the ejection speed of the ink droplet is increased, the ejection direction is stabilized, and the landing position on the recording medium becomes constant even if there is air resistance or the like.

Further, in the present invention, since the ink droplets are ejected by irradiating the ink with a laser beam, the acoustic radiator required for the conventional ink jet recording head using the acoustic wave is not required. It is possible to increase the density of ink ejection positions in one inkjet recording head. As a result, high-speed and high-density image recording becomes possible.

The specific structure for generating a shock wave in the ink held by the ink holding member is not particularly limited. For example, by applying the energy of laser light to the ink, bubbles whose expansion speed exceeds the sound speed can be reduced. Raise,
There is a configuration in which a spherical shock wave is generated by the bubble.

By the way, a shock wave is generated from a laser beam irradiation position, and an ink droplet is ejected when it reaches a gas-liquid interface. The drop diameter of the ejected ink droplet depends on the volume of the ink in a region where the shock wave spreading in the ink has propagated. In the present invention, since the distance between the laser light irradiation position from the bubble generating means and the gas-liquid interface of the ink held by the ink holding member can be changed by the distance changing means, the spread of the shock wave is substantially increased. The size can be changed. Thus, the drop diameter of the ink droplet can be changed by one ejection operation.

The distance is an amount appropriately determined depending on the viscosity of the ink, the amount of energy applied to the ink, and the like. For example, the distance is set to about 0.1 to 10 times the desired drop diameter. And more preferably about 0.5 to 5 times.

According to a second aspect of the present invention, in the first aspect of the present invention, the laser light from the bubble generating means is provided on the ink holding member, and the laser light is applied to a predetermined position of the ink held by the ink holding member. A laser light derivative that sets a position where a shock wave is generated by being guided.

As the laser derivative, a member having a high transmittance with respect to the wavelength of the laser beam applied to the ink can be used.

Further, as an example of such a laser beam derivative, a transmission hole formed on the laser beam irradiation surface of the ink holding member can be mentioned. That is, the ink held by the ink holding member and the outside air on the laser light irradiation surface side are in contact with each other through the transmission holes. By doing so, the laser light can be directly applied to the ink, and there is no energy loss of the laser light.

As described above, by guiding a laser beam to a predetermined position using a laser beam derivative, ink droplets can be ejected from a desired position, and an image can be recorded with higher precision.

In the case where a laser beam derivative is used, the laser beam derivative is disposed between the ink held by the ink holding member and the bubble generating means as described in claim 3. And the distance changing means can be configured by partially changing the plate thickness of the laser light transmitting member.

This makes it possible to change the drop diameter of the ink droplet with a simple configuration that only partially changes the thickness of the laser light transmitting member.

Further, the laser light transmitting member is substantially
Since it can be provided as a part of the wall constituting the ink holding member, the laser beam derivative can be formed without increasing the number of parts.

According to a fourth aspect of the present invention, there is provided an ink jet recording head according to any one of the first to third aspects, an ink supply device for supplying ink to an ink holding member of the ink jet recording head, and the air bubble. A laser light scanning device for scanning the laser light from the generating means,
An image recording control device capable of controlling the ink jet recording head, the ink supply device, and the laser beam scanning device in accordance with image information.

That is, when an image recording signal corresponding to image information is input, the ink held by the ink holding member, which is a component of the ink jet recording head, is irradiated with laser light by the bubble generating means, The laser beam is scanned in a predetermined direction (scanning direction) by the optical scanning device.

The specific configuration of the laser beam scanning device is not particularly limited as long as the recording medium and the laser beam are relatively moved and scanned. For example, when the bubble generating means is composed of a laser light generator and a condenser lens, the laser light generator and the condenser lens are held by a holding member such as a carriage, and the holding member is moved. Thus, the laser light generator and the condenser lens may be integrally moved. Alternatively, the laser light generator and the carriage may be fixed, and only the laser light may be scanned by a polygon mirror, a rotating mirror, or the like. Further, the laser light generator and the condenser lens may be fixed and the recording medium may be moved.

Further, since the ink jet recording head constituting this ink jet recording apparatus does not have a nozzle, even if the ink discharge positions are arranged at a high density, nozzle clogging, discharge failure caused by this clogging, and nozzle clogging may occur. Inconveniences such as a delay in the ink supply speed and the image recording speed due to the high flow path resistance do not occur. Further, since the maintenance operation of the nozzle is not required, the image recording is not interrupted on the way. In addition, conventional lasers
Compared to an inkjet recording device equipped with an addressing type bubble jet recording head, the ejection speed of ink droplets is higher, so the ejection direction is stable, and the landing position on the recording medium is constant even if there is air resistance etc. Position.

Also, compared with a conventional ink jet recording apparatus having an ink jet recording head using acoustic waves, it is possible to increase the density of ink ejection positions and to record images at high speed. .

In addition, the drop diameter of the ink droplet can be changed by one ejection operation.

[0038]

FIG. 1 shows a basic configuration of an ink jet recording head 10 according to a first embodiment of the present invention.

The ink-jet recording head 10 includes an ink holding member 1 disposed below a sheet P (recording medium).
Two. The ink holding member 12 is formed in a box shape, and has an upper surface opened to form an ink discharge port 14. Therefore, the ink ejection port 14 always faces the paper P, and the ink droplet 16 ejected from the ink ejection port 14 lands on the paper P, and an image is recorded on the surface of the paper P.

Note that, as long as the ink discharge port 14 faces the paper P, the irradiation position of the laser light described later and the position of the paper P are not particularly limited.

The ink holding member 12 stores ink 18 supplied by an ink supply device (not shown). Further, an ink amount sensor 20 (for example, a photo sensor or the like) for detecting the amount of the ink 18 is attached inside the ink holding member 12. The ink supply device and the ink amount sensor 20 are connected to the control device 22, and the ink supply amount is adjusted so as to have a predetermined ink amount.

Below the ink holding member 12, a laser light generator 24 constituting the bubble generating means of the present invention and a condenser lens 26 for condensing the laser light generated from the laser light generator 24 are arranged. ing. The laser light generator 24 is connected to the controller 22 and emits a laser light 28 corresponding to the image information.

The condenser lens 26 is provided with the laser light generator 2
The laser light 28 emitted from 4 is condensed to increase the energy density, and is applied to the boundary between the bottom of the ink holding member 12 (constituting the laser light derivative of the present invention) and the ink 18.

The bottom of the ink holding member 12 is constituted by a laser beam derivative 30 formed in a substantially flat plate shape. The laser light derivative 30 is formed of a member (for example, a transparent plate) having a high transmittance with respect to the wavelength of the irradiated laser light. The laser light 28 condensed by the condensing lens 26 passes through the laser light derivative 30, and the upper surface of the laser light derivative 30, that is, the ink 18 held by the ink holding member 12 and the laser light derivative 30 The boundary is irradiated. The ink 18 is
In order to efficiently absorb the laser energy, it is preferable that the laser light is hardly transmitted. Thereby, high-density energy is applied to the interface between the ink 18 and the laser beam derivative 30 in accordance with the image information. The intensity of the energy depends on the ink 18 irradiated with the laser light 28.
Causes a phase change, and bubbles 3 whose expansion speed is faster than the speed of sound
8 is set to be strong enough to produce 8.

The laser beam derivative 30 has a thick portion 30A formed on the left side of FIG. 1 and a thin portion 30 formed on the right side.
C and an inclined portion 30B that is linearly inclined between the thick portion 30A and the thin portion 30C. This allows
The distance T from the upper surface of the laser beam derivative 30, that is, the bubble generation portion to the gas-liquid interface 34 (the interface between the ink 18 and the air) continuously changes. Then, the irradiation position of the laser light 28 is changed in the direction of the arrow Y by a deflection device (not shown), and the desired position of the laser light derivative 30 (any desired one of the thick part 30A, the inclined part 30B and the thin part 30C) Position).

A transport roller 42 controlled by a paper feed control device 40 is provided above the ink holding member 12. The rotation of the transport roller 42 transports the sheet P in a certain direction.

Further, the inkjet recording head 10 is provided with a scanning device (not shown) for scanning the paper P with the laser beam 28 in the direction of arrow X. And
Scanning (main scanning) by the scanning device and conveyance (sub-scanning) of the paper P by the conveyance roller 42 are performed alternately, and the paper P
The desired image is recorded on the.

In the ink jet recording head 10 of the first embodiment having such a basic configuration, when the laser light 28 is generated from the laser light generator 24 in accordance with the image information, the laser light 28 is collected. The laser light is condensed by the lens 26, passes through the laser light derivative 30, and is applied to the boundary between the ink 18 held by the ink holding member 12 and the laser light derivative 30.

The ink 18 irradiated with the laser light 28 undergoes a phase change, and bubbles 38 are generated in the ink 18.
When the bubble 38 expands at an expansion speed higher than the speed of sound, a spherical (more strictly, substantially hemispherical) shock wave 32 is generated in the ink 18, and the gas-liquid interface 34 (the ink 18 Interface with air). Since the impact impedance of the ink 18 is different from that of the air, the energy of the shock wave 32 acts as kinetic energy on the ink 18 without being transmitted to the air, and the ink droplet 16 is ejected from the gas-liquid interface 34 toward the paper P. Then, the ink droplet 16
Land on the sheet P, and a desired image is recorded on the surface of the sheet P. Note that the bubbles 38 generated in the ink 18 disappear in a very short time, and thus do not affect the subsequent ejection of the ink droplets 16.

Here, the size of the ejected ink droplet 16 depends on the volume of the ink 18 in the area where the shock wave 32 propagates. That is, the larger the shock wave 32 is, the larger the ink droplet 18 is. Also, as can be seen from FIG. 1, the magnitude of the spread of the shock wave 32 depends on the thickness T of the ink layer.
The larger the thickness T, the more the shock wave 32 spreads.

Here, the laser light 28 is deflected in the direction of arrow Y in FIG. 1 by a deflecting device (not shown), and is irradiated to a desired position of the laser light derivative 30 in accordance with the image information. I have. As a result, the laser beam is irradiated to the position where the thickness of the laser light derivative 30, that is, the thickness T of the ink layer is different, so that the ink droplet 16 having a predetermined drop diameter corresponding to the thickness T of the ink layer is ejected. You.

The deflecting device for deflecting the laser light to the position of the ink 18 having the thickness T corresponding to the desired drop size as described above is not particularly limited. For example, the laser light generating device 24 and the condenser lens 26 May be integrally moved in the direction of arrow Y of the ink holding member 12. However, the laser light generator 24 and the condenser lens 26 are fixed, and a mirror is provided between the condenser lens 26 and the ink holding member 12. (Polygon mirror, rotating mirror, etc.) is installed and the direction of this mirror is changed.
A configuration in which only scanning is performed may be used.

As described above, in the ink jet recording head 10 of this embodiment, the thick portion 3
The thickness T of the ink layer is changed depending on the position by forming 0A, the inclined portion 30B, and the thin portion 30C. Therefore, by changing the irradiation position of the laser beam 28 by a deflecting device (not shown), a different thickness T corresponding to the irradiation position is obtained.
Since the ink 18 is irradiated with the laser beam 28, the drop diameter L of the ink droplet 16 can be changed, and the ink droplet 16 having a desired drop diameter L can be ejected.

Further, the thickness T of the ink layer is continuously changed by the inclined portion 30B formed in the laser beam derivative 30. Therefore, the drop diameter of the ink droplet 16 can also take a continuous value.

The thickness T of the ink layer should be about the desired minimum drop diameter at the thinnest point and about the desired maximum drop diameter at the thickest point in relation to the drop diameter L of the ink droplet 16 to be ejected. It is preferable that the thickness between them can be set arbitrarily within this range.

The thickness T of the ink layer in the ink holding member 12
Since the volume of the ink 18 in the region where the shock wave generated when the bubble 38 expands propagates is substantially equal to the volume (drop volume) of the ink droplet 16 to be ejected, the ink droplet 16 is reduced to a desired drop diameter. It is preferable to set the thickness T of the ink layer to a desired drop diameter. Specifically, it is more preferably 0.1 to 10 times, and more preferably 0.5 to 5 times the desired drop diameter. The drop diameter of the ink droplet required in a general inkjet recording head is 10 to 50.
μm, the thickness T is 1 to 50
A range of 0 μm is preferable, and a range of 5 to 250 μm is particularly preferable. For example, it is possible to configure so that the drop diameter L is equal to the thickness T of the ink layer. As an example of this case, the distance T to the gas-liquid interface is set to 20 μm to 8 μm.
Laser light derivative 3 that changes continuously to 0 μm
If 0 is used, the drop diameter L of the ink droplet 16 can be continuously modulated from 20 μm to about 80 μm.

The drop diameter D of the ejected ink droplet 16 is determined by the area to which the energy of the laser light 28 is applied,
That is, it is related to the irradiation area of the laser light 28. For example, a substantially circular laser beam 28 is irradiated and the ink 1 is irradiated.
When energy is applied to 8, bubbles 38 having a diameter equal to or smaller than the irradiation diameter are generated. Then, the bubble 38 expands, and the ink droplet 16 having the same volume as the expanded bubble 38 is ejected. Therefore, the laser light derivative 30 and the ink 18
It is preferable that the irradiation diameter of the laser beam 28 at the interface with the target is not more than a desired drop diameter.

As described above, as a method of obtaining the irradiation diameter of the laser beam 28 having a diameter smaller than a desired drop diameter, the laser beam output from the laser beam generator 24 is condensed by using the condenser lens 26 as in this embodiment. However, the method is not limited to this, and a method of outputting a laser beam having a spot diameter equal to or smaller than the drop diameter from the laser beam generator 24 may be used. As in the latter case, the method of outputting a laser beam having a spot diameter equal to or smaller than the drop diameter from the laser beam generator 24 involves passing through the condenser lens because there is no separate condenser lens in addition to the laser beam generator 24. This is preferable because there is no loss of energy of the laser light 28 due to this and the size of the ink jet recording head 10 can be reduced.

On the other hand, the method using the condensing lens 26 is high even in the laser light generator 24 having a weak output by making the spot diameter of the light incident on the condensing lens 26 small by passing through the condensing lens 26. Irradiation energy density is obtained. Therefore, by appropriately selecting the characteristic value of the condenser lens 26 such as the focal length, the output range of the laser light generator 24 to be used can be widened. In addition, it is generally widely used as a method for reducing the irradiation area, and is easily incorporated into the inkjet recording head 10. From these points, the method using the condenser lens 26 is more preferable as a method for obtaining a laser irradiation diameter smaller than the drop diameter.

As a specific example, when a laser beam having an output P ₁ is passed through a condenser lens having a focal length f ₁ ,
If the energy density is assumed to be I _1, the output P ₂ = 1 /
To obtain the same energy density as I ₁ in 2P ₁ ,
This can be realized by using a condenser lens having a focal length f ₂ = (1 / √2) f ₁ .

As the condensing lens 26 of this embodiment, any lens can be used as long as the irradiation area can be reduced by passing the laser beam 28. For example, an optical lens such as a convex lens, a compound lens, or an aspherical lens can be used. Aspheric lenses are more preferred in that they have less aberration.
The material is preferably made of a borosilicate glass such as BK7 or Pyrex generally used as a laser optical device, or made of synthetic quartz.

Further, in order to suppress energy loss of the laser beam 28 caused by passing through the condenser lens 26, it is more preferable to perform a surface treatment such as applying an antireflection film for improving the transmittance to the condenser lens 26. . As the material of the antireflection film, for example, magnesium fluoride (MgF
₂ ), chromium (Cr), a combination of aluminum and magnesium fluoride (Al + MgF ₂ ), or the like can be used. The surface treatment with such a material is more preferable because the transmittance can be improved by 5% or more.

As the laser light generator 24, various types of laser light generators which are generally used can be used. However, when the laser light 28 is irradiated on the ink 18, the physical properties of the ink 18 should not be changed. Is desirable,
From such a viewpoint, a laser having a wavelength in a range from visible light to near infrared region, for example, a YAG laser, helium-neon (He
-Ne) It is preferable to use a laser, a semiconductor laser, or the like.

From the viewpoint of output, it is preferable to use a pulse laser capable of high output. AO (ultrasonic light) modulator and EO
An (electric light) modulator may be connected and used in a pulsed manner. Further, since the output of the semiconductor laser can be directly modulated at a high speed by a change in current, the above-described AO modulator and EO modulator are not required, and the device can be downsized. Direct modulation means used in AO modulators and semiconductor lasers is preferable in that the repetition frequency of pulse waves can be set to megahertz or higher in principle, so that the repetition frequency can be increased.

The output range of the laser light generator 24 may be of a size that allows the energy applied to the ink 18 by the irradiation of the laser light 28 to generate bubbles 38 in the ink 18 and generate a shock wave. In the present invention, although it depends on the configuration of the member to be used and the range of the characteristic value and the physical property value of the member, it is specifically 1 μJ or more.

The ink holding member 12 is, as described above,
A laser light derivative 30 is provided on the side irradiated with the laser light 28.
And a side wall 36 erected from the periphery of the laser beam derivative 30 so as to form a box shape having an open upper surface as a whole. With this side wall 36,
The ink 18 can be held so as to surround the laser light derivative 30. Of course, as long as the ink 18 can be held, the shape of the ink holding member 12 is not limited to the above. Further, the ink ejection port 14 does not necessarily need to be formed over the entire upper surface of the ink holding member 12. For example, the ink holding member 12 may have an upper plate, and the ink discharge ports 14 may be partially formed in the upper plate.

The laser light derivative 30 of the present invention is located between the ink 18 held by the ink holding member 12 and the bubble generating means (more precisely, the condenser lens 26), and is generated by the laser light generating device 24. Laser light 28
And means for applying the energy of the laser light 28 to the ink. At this time, since the bubbles 38 are generated on the laser light derivative 30 on the ink 18 side, the generation position of the bubbles 38 is determined by the position of the laser light derivative 30 in the ink holding member 12. For example, as shown in FIG. 1, when the laser beam 28 is irradiated from below, the laser beam derivative 30 can eventually constitute the bottom surface of the ink holding means, and the laser beam derivative 30 can be used without increasing the number of parts. 30 can be provided. As shown in FIGS. 7 and 8, the side wall 36 of the ink holding member 12 is made of a laser beam derivative processed into a plate shape, and the laser light generator 24 and the condenser lens 26 are located on the side And place
The laser beam 28 may be applied to the ink 18 through the side wall 36 which is a laser beam derivative. In this case, for example, as shown in FIG. 7, a rotating mirror 42 rotatable around the rotation axis J is provided in the optical path of the laser light 28, and the irradiation position of the laser light 28 is changed by changing the angle of the rotating mirror 42. It is possible to set the generation position of the bubble 38 to a desired position. As shown in FIG. 8, the laser light generator 24 and the condenser lens 26 are integrally held by the holding member 44, and the worm gear 46 provided on the holding member 44 is rotated by the motor 48 to thereby generate the laser light 28. May be changed so that the bubble 38 is generated at a desired position. In any case, the distance (substantially the thickness T of the ink layer) from the irradiation position of the laser beam 28 to the gas-liquid interface 34 changes, so that the drop diameter L of the ink droplet 16 is changed. It is possible to eject ink droplets 16 having a desired drop diameter L.

In the configuration shown in FIGS. 7 and 8, the laser beam 28 is formed by a side wall 36 which is a laser beam derivative.
Irradiation is performed on the boundary surface between the ink and the ink 18, so that a bubble 38 is generated on the boundary surface, a shock wave is generated, and the shock wave propagates into the ink 18. Therefore, when the ink droplets 16 are ejected,
The energy is attenuated by the meniscus formed between the ink droplet 18 and the ink droplet 16 or the ink droplet 16.
May become unstable. Considering this, the side wall 36 is opposite to the ink 18 as shown in FIG. 9B, as compared with the case where the gas-liquid interface 34 is perpendicular to the side wall 36 as shown in FIG. 9A. It is preferable to install at a predetermined inclination angle θ toward the side (outside) to reduce the influence of meniscus.

As long as such conditions are satisfied, the laser light derivative of the present invention is not limited to the laser light derivative 30 described above. However, the laser light derivative contains impurities or absorbs light of a specific wavelength. If it is, the laser light derivative 30 absorbs the energy of the laser light 28 and the ink contains bubbles 38 and shock waves 32.
May not be provided with sufficient energy to generate In addition, when the absorbed energy is large, the laser beam derivative may be damaged.
Therefore, as the laser light derivative 30, it is preferable to use a transparent member for the irradiated laser light 28, that is, a transparent member having a high transmittance with respect to the wavelength of the laser light 28. Specifically, the transmittance is preferably 90% or more.

Further, it is more preferable to perform a surface treatment such as coating an antireflection film for improving the transmittance on the transparent member. As the material of the antireflection film, for example,
Magnesium fluoride (MgF ₂ ), chromium (Cr), a combination of aluminum and magnesium fluoride (Al + MgF ₂ ), or the like can be used. A transparent member surface-treated with such a material is more preferable because transmittance can be improved by 5% or more.

The transparent member may be made of any material having a strength that is not destroyed by the energy of the irradiated laser light 28. As such an index, a laser damage threshold (also referred to as an energy safety threshold) is used. This indicates the value of the energy of the laser light 28 applied per unit area (1 cm ² ) for preventing the laser irradiation member (the laser light derivative 30 in the present invention) from being damaged.

In order to eject the ink droplet 16 within the energy range of the laser beam 28 used in the present embodiment, specifically, the energy damage threshold when the damage rate is 1% or less is 5 J /. cm ² or more. As such a material, for example, synthetic quartz or fused quartz can be used.

FIG. 2 shows the basic configuration of an ink jet recording head 210 according to a second embodiment of the present invention. Hereinafter, the same components, members, and the like as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the ink jet recording head 210, the laser light derivative 230 formed in a substantially flat plate shape
Instead of the inclined portion 30B of the first embodiment, a thick portion 230A
Part 230D having an intermediate thickness between thin part 230C and thin part 230C
Is formed, and has a substantially stepped shape in three steps, and the thickness T of the ink layer also changes in three steps.

Further, similarly to the first embodiment, the irradiation position of the laser light 28 on the laser light derivative 230 can be changed to a desired position in the arrow Y direction by a deflection device (not shown).

Further, the ink jet recording head 210
Is provided with a scanning device (not shown) for scanning the paper P with the laser beam 28 in the direction of the arrow X. The scanning by the scanning device (main scanning) and the conveyance roller 42
And the conveyance (sub-scanning) of the sheet P is performed alternately, and a desired image is recorded on the sheet P.

Therefore, the ink jet recording head 2
When the ink droplet 16 is ejected using the nozzle 10, the laser beam is deflected in the Y direction to a position corresponding to a desired drop diameter, so that the drop diameter L can be changed in three stages. .

Further, as compared with the inclined portion 30B of the first embodiment, the thickness of the intermediate portion 230D is constant, and the thickness T of the corresponding ink layer is also constant.
The drop diameter of the ink droplet 16 ejected by the bubble 38 generated in D and the shock wave 32 is stabilized.

Note that the number of steps formed on the laser beam derivative 230 is not limited to the above-described three steps, and is appropriately determined in consideration of a desired drop diameter of the ink droplet 16. Therefore, the number of stages may be two or four or more.

FIG. 3 shows an ink jet recording head 310 according to a third embodiment of the present invention. Hereinafter, the first
Constituent elements, members, and the like that are the same as in the embodiment or the second embodiment are given the same reference numerals, and descriptions thereof are omitted.

In the ink jet recording head 310, unlike the first and second embodiments, the laser beam derivative 330 is formed in a flat plate shape having a constant plate thickness.

An ink circulation hole 312 is formed in the side wall 36 of the ink holding member 12.
And the ink tank 314 are connected by a tube 316 having a valve mechanism (not shown). Further, a pump 318 is provided at an intermediate portion of the tube 316. Ink tank 314, pump 318 and tube 3
16 constitutes the ink amount adjusting device of the present invention.

Further, in addition to the ink amount sensor 20 and the laser light generator 24, a pump 318 is also connected to the controller 22.

Further, the ink jet recording head 310
Is provided with a scanning device (not shown) for scanning the paper P with the laser beam 28 in the direction of the arrow X. The scanning by the scanning device (main scanning) and the conveyance roller 42
And the conveyance (sub-scanning) of the sheet P is performed alternately, and a desired image is recorded on the sheet P.

In the ink jet recording head 310 of the third embodiment having such a configuration, the ink amount sensor 2
The control device 22 controls the pump 318 based on the information on the amount of ink detected by 0 to supply or suck the ink 18 to the ink holding member 12. Thereby, the gas-liquid interface 3
Since the height of the ink droplet 16 changes and the thickness T of the ink layer also changes, it is possible to change the drop diameter of the ejected ink droplet 16.

As described above, the height of the gas-liquid interface 34 is changed without changing the height of the bottom of the ink holding member 12, and
A desired drop diameter may be obtained by directly changing the thickness T of the ink layer in the ink holding member 12.

FIG. 4 shows an ink jet recording head 410 according to a fourth embodiment of the present invention. Hereinafter, the first
The same reference numerals are given to the same components, members, and the like as those in the embodiments to the third embodiment, and description thereof will be omitted.

The ink jet recording head 410 of the fourth embodiment does not have the ink circulation holes 312, the ink tanks 314, the tubes 316, and the pumps 318 of the third embodiment.
Inside, two partition walls 412 and 414 parallel to the side wall 36 are erected. The partitions 412 and 414 allow the ink holding member 12 to have three ink chambers 41 having substantially the same width.
6A, 416B and 416C.

Each of the ink chambers 416A, 416B,
At 416C, an ink amount sensor 20 connected to the control device 22 is provided (only the connection structure corresponding to the ink chamber 416C is shown, and the others are not shown). Each of the ink chambers 41 is formed such that the thickness T of the ink layer in the ink chamber 416A is the thinnest and the thickness T gradually increases toward the ink chambers 416B and 416C.
The ink amounts of 6A, 416B, and 416C are adjusted.

Further, similarly to the first and second embodiments, the irradiation position of the laser light 28 on the laser light derivative 330 can be changed to a desired position in the arrow Y direction by a deflection device (not shown). It has become.

Further, the ink jet recording head 410
Is provided with a scanning device (not shown) for scanning the paper P with the laser beam 28 in the direction of the arrow X. The scanning by the scanning device (main scanning) and the conveyance roller 42
And the conveyance (sub-scanning) of the sheet P is performed alternately, and a desired image is recorded on the sheet P.

In the ink jet recording head 410 of the fourth embodiment having such a structure, the ink chamber 4
Since the thickness T of the ink layer is changed in each of 16A, 416B and 416C, by deflecting the laser light in the Y direction to a position corresponding to a desired drop diameter,
The drop diameter of the ink droplet 16 discharged from each ink chamber also changes.

In the fourth embodiment, the number of ink chambers provided in the ink holding member 12 is not limited to the above-described three, and is appropriately determined in consideration of a desired drop diameter of the ink droplet 16. Therefore, the number may be two or four or more.

FIG. 5 shows an ink jet recording head 50 according to a fifth embodiment of the present invention. Hereinafter, the first to first
The same components, members, and the like as in the fourth embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the ink jet recording head 50,
The bottom plate 54 of the ink holding member 52 is made of the same plate material as the side wall 36.

Further, a plurality of optical fibers 56 as a laser beam derivative of the present invention are attached to the bottom plate 54 at predetermined intervals so as to obtain a desired resolution. The lower end of each optical fiber 56 is flush with the bottom surface of the bottom plate 54, that is, the irradiation surface of the laser beam 28, and the laser beam 28 condensed by the condenser lens 26 is irradiated. The upper end of the optical fiber 56 is located below the inside of the ink 18 held by the ink holding member 52, that is, below the gas-liquid interface 34, and its height decreases in order from the left end to the right side in FIG. The length of each optical fiber 56 is determined.

Further, similarly to the first embodiment, the irradiation position of the laser light 28 is changed by an arrow Y by a deflection device (not shown).
The direction can be changed to a desired position.

Further, the inkjet recording head 50 is provided with a scanning device (not shown) for scanning the paper P with the laser beam 28 in the direction of arrow X. And
Scanning (main scanning) by the scanning device and conveyance (sub-scanning) of the paper P by the conveyance roller 42 are performed alternately, and the paper P
The desired image is recorded on the.

In the ink jet recording head 50 according to the fifth embodiment having such a configuration, the laser light 28 applied to the lower end of the optical fiber 56 is guided by the optical fiber 56 to the upper end position, that is, the inside of the ink 18. A bubble 38 is generated at the position. And the first
As in the embodiment, the bubble 38 expands at an expansion speed faster than the speed of sound, and a spherical shock wave 32 is generated in the ink 18 to reach the gas-liquid interface 34 (the interface between ink and air). Then, due to the difference in the shock impedance between the ink 18 and the air, the energy of the shock wave acts on the ink 18 as kinetic energy, and the ink droplet 16 flies from the gas-liquid interface 34 toward the paper P, and Is recorded.

Here, as described above, the optical fiber 5
The height of the upper end of the lower portion 6 decreases in order from the left end to the right side of FIG. It is gradually getting longer. For this reason, the shock wave 32 generated from the optical fiber 56 on the right side is also larger than the shock wave 32 generated from the optical fiber 56 on the left side in FIG. For this reason, the drop diameter of the ejected ink droplet 16 changes corresponding to each optical fiber 56. Moreover, since the lengths of the plurality of optical fibers 56 are changed in multiple steps, the positions corresponding to the desired drop diameter are
By deflecting the laser light in the Y direction, the drop diameter L can be changed in multiple stages.

The distance between the upper end of the optical fiber 56 and the gas-liquid interface is determined by the desired drop diameter and laser output. Preferably, the distance between the upper end of the optical fiber 56 and the gas-liquid interface 34 is 0.1 to 1 of a desired drop diameter.
It is preferably about 0 times, and more preferably about 0.5 to 5 times.

By using the optical fiber 56 in this manner, even if the thickness of the ink layer is larger than the desired drop diameter, the optical fiber 56 (laser light derivative) can be used regardless of the thickness of the ink layer. Has the effect of being arranged at a desired distance. Further, since the thickness of the ink layer is increased, drying of the ink from the ink holding member 52 can be prevented.

The optical fiber 56 is an example of the laser light derivative of the present invention, and can be made of the same material as the laser light derivative 30 of the first embodiment from the viewpoint of transmitting the laser light.

Since the core diameter of the optical fiber 56 affects the size of the ink droplet 16 to be ejected, it is preferable that the laser beam irradiation area be smaller than a desired drop diameter.

The optical fiber 56 may be of a single mode type or a multi mode type.

FIG. 6 shows an ink jet recording head 70 according to a sixth embodiment of the present invention.

In this ink jet recording head 70,
The basic configuration is the same as that of the ink jet recording head 10 according to the first embodiment.
2. A screw feed mechanism (irradiation area changing means) constituted by the worm gear 74 and the stepping motor 76 is provided.

The lens holder 72 holds the condenser lens 26 and has a screw hole formed therein, and a worm gear 74 is inserted into and engaged with the screw hole. The worm gear 74 is driven by a stepping motor 76 connected to the control device 22 so that the ink droplet 16
Is rotated by a predetermined number of revolutions corresponding to the drop diameter L of Therefore, in conjunction with the rotation of the worm gear 74, the condenser lens 26 moves by a predetermined distance in the optical axis direction of the laser light 28 (vertical direction in FIG. 1). Then, the irradiation area of the laser beam 28 to the ink 18 held by the ink holding member 12 changes due to the movement of the condenser lens 26.

In the ink jet recording head 70 of the sixth embodiment having such a structure, the ink droplet 16 can be moved by moving the condenser lens 26 in the optical axis direction of the laser light 28 in conjunction with the rotation of the worm gear 74. It is possible to change the drop diameter. That is, the size of the ejected ink droplet 16 depends not only on the above-described thickness T of the ink layer, but also on the volume of the ink 18 spread by the shock wave 32. The volume of the ink 18 spread by the shock wave 32 is related to the size of the bubble 38 generated by the irradiation of the laser light 28. That is, the larger the bubble 32, the larger the ink droplet 18 becomes.

Therefore, by using the change in the thickness T of the ink layer and the change in the irradiation area of the laser beam 28 together, it is possible to make the drop diameter more multi-step.

Note that the irradiation area changing means is not limited to the above-described screw feed mechanism. For example, the condenser lens 26
Instead, a stop used in a general optical system or the like may be provided to change the irradiation area of the laser beam 28. Since the condenser lens 26 is not used in the configuration in which the stop is provided, there is no energy loss due to the transmission of the laser light 28 through the condenser lens 26. In addition, laser light 28
Is constant regardless of the size of the irradiation area. In addition, the size of the inkjet recording head itself can be reduced as compared with the case where the condenser lens 26 is used.

Further, such an irradiation area changing means may be provided not only in the ink jet recording head 10 of the first embodiment but also in any one of the ink jet recording heads of the second to fourth embodiments.

When the irradiation area changing means is provided in the ink jet recording head 50 of the fifth embodiment, the irradiation area of the laser light 28 can be changed by changing the thickness of the optical fiber 56. it can.

As described above, in any one of the ink jet recording heads of the present invention, an image can be recorded on the surface of a recording medium by flying ink droplets without using a conventional nozzle. Even if the 16 discharge positions are arranged at a high density, nozzle clogging does not occur, and there is no discharge failure due to nozzle clogging. In addition, in an ink jet recording head having a nozzle, the ink supply speed is reduced due to a high flow path resistance of the nozzle, and the image recording speed is sometimes reduced. No image can be recorded at high speed. No nozzle maintenance operation (vacuum operation or wiping operation) is required, so that image recording is not interrupted halfway.

Further, in the ink jet recording head of the present invention, a large energy is given to the ink by generating a shock wave in the ink, and the ink is compared with the conventional laser addressing type bubble jet recording head. The ejection speed of the droplet increases. For this reason, the ejection direction of the ink droplet 16 is stabilized, and even if there is air resistance or the like, the landing position on the recording medium is constant, and a high-quality image can be formed.

Further, in the present invention, the energy is applied by ejecting the laser beam 28 to the ink 18 to discharge the ink droplets 16, so that the energy is applied to the ink by a conventional acoustic wave. The acoustic radiator of the ink jet recording head becomes unnecessary. Therefore, 1
The density of ink ejection positions can be increased in one inkjet recording head, and high-speed and high-density image recording can be performed.

In addition, the ink jet recording head of the present invention can change the drop diameter L of the ink droplet 16 to be ejected in one ejection operation. To record images.

If the energy for discharging the ink droplet 16 can be applied to the ink 18 by the irradiation of the laser beam 28, the laser beam derivative (the laser beam derivative 30,
A configuration without the optical fiber 56 and the transmission hole 76) may be used. That is, the laser beam 28 may be irradiated from the ink ejection port 14 side, and the bubble 38 may be generated at a position from the gas-liquid interface into the ink about the drop diameter.

An ink jet recording apparatus according to the present invention is an ink jet recording apparatus provided with the ink jet recording head according to any one of the above embodiments. Therefore, even in this ink jet recording apparatus, an image can be recorded on the surface of the recording medium by flying the ink droplet 16 without using a conventional nozzle, so that even if the ejection positions of the ink droplet 16 are arranged at a high density. No nozzle clogging occurs, and there is no ejection failure due to nozzle clogging. In an ink jet recording apparatus having an ink jet recording head having nozzles, the ink supply speed and the image recording speed were sometimes reduced due to the high flow resistance of the nozzles. An ink jet recording apparatus having a head can record an image at high speed without these inconveniences. No nozzle maintenance operation (vacuum operation or wiping operation) is required, so that image recording is not interrupted halfway.

In the ink jet recording apparatus provided with the ink jet recording head of the present invention, a large energy is given by generating a shock wave in the ink.
The ejection speed of ink droplets is higher than that of an ink jet recording apparatus having a conventional laser addressing type bubble jet recording head. For this reason, the ejection direction of the ink droplet 16 is stabilized, and even if there is air resistance or the like, the landing position on the recording medium is constant, and a high-quality image can be formed.

In addition, since ink droplets 16 having a desired drop diameter L can be ejected by a single ejection operation without overlapping a plurality of ink droplets, even in a case where a wide area is painted out. It can record images at high speed.

[0122]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

In this example, as shown in FIG. 10, the ink droplet 16 was ejected toward the recording medium P using the ink jet recording head 210 of the second embodiment of the present invention.

The laser beam derivative 230 constituting the bottom of the ink holding member 12 is made of synthetic quartz having a laser damage threshold of 8 J / cm ^{2. In} this embodiment, the dimensions are 257 mm in width and 10 mm in depth. The thick part 230
A, an intermediate part 230D and a thin part 230C are formed in a substantially three-step shape. Further, the portion of the ink holding member 12 other than the laser light derivative 230 is made of polyetherimide, and the thin portion 230 of the laser light derivative 230 is formed.
The side wall 36 having a height of 200 μm from the upper surface of C was arranged so as to surround the laser light derivative 230, and the upper surface was completely opened to form the ink ejection port 14. Further, the amount of ink in the ink holding member 12 is detected by the ink amount sensor 20, and ink is supplied by ink supply means (not shown) connected to the ink holding member 12, so that the gas-liquid interface 34 is provided.
Is 10 μm at the thick portion 230A and the intermediate portion 23
It was held so as to be 20 μm at 0D and 50 μm at the thin portion 230C.

As the laser beam generator 24, the output 2
W, an InGaAsP semiconductor laser with a wavelength of 635 nm, and a modulation frequency of 60 kHz, 1 pulse per pulse.
The output of the laser was set to 600 mW, and the modulation width (pulse width) of the output was set to 8.35 μsec so as to be 0 μJ. At this time, even if the laser light is continuously irradiated, the frequency modulation automatically switches between the case where the energy sufficient for ejecting the ink droplet is obtained by the output modulation and the case where the energy is less than this energy.

The laser beam 28 condensed by the condenser lens 26 was converted into parallel light by a synthetic quartz concave lens (φ6.35 mm) 232 having a laser damage threshold of 8 J / cm ² .

Further, the laser light 28 converted into parallel light
Was deflected using a polygon mirror 234.

A reflection mirror 236 is disposed between the polygon mirror 234 and the laser light derivative 230 so as to be rotatable around the rotation axis J. By changing the angle of the reflection mirror 236, the laser light 28 is emitted. Light derivative 23
0 thick part 230A, middle part 230D and thin part 230
The bottom surface corresponding to each of C was irradiated.

Further, the sheet P is set in the sheet width direction (arrow X).
When the scanning of the laser beam 28 in the direction ()) is completed, the conveying roller 42 is rotated by a signal from the paper feed control device 40, and the paper P is sent to the next image recording position.
When image recording was performed by ejecting ink droplets 16 having different drop diameters, the paper P was transported to a position corresponding to a desired drop diameter.

Using the ink jet recording head 210 having such a configuration, the above-mentioned InGaAsP semiconductor laser is pulsed at 8.35 μsec, output is 10 μJ, and
Output modulation frequency (corresponding to printing frequency) is 60 kHz
To generate a laser beam 28, and the condensing lens 26
To irradiate the interface between the laser light derivative 230 and the ink 18. Here, first, the laser light 28
When the angle of the reflection mirror 236 was adjusted so that the light was irradiated to the position corresponding to the thick portion 230A, and the laser light 28 was scanned in the direction indicated by the arrow X in FIG.
An ink droplet 16 having a drop diameter of 10 μm is ejected from the gas-liquid interface 34 corresponding to the thick portion 230A in the gas phase direction,
The image landed on the paper P was recorded. Next, the paper P is fed, and the angle of the reflection mirror 236 is adjusted so that the laser light 28 is irradiated to the position corresponding to the intermediate portion 230D. Accordingly, the gas-liquid interface 3 corresponding to the intermediate portion 230D
An ink droplet 16 having a drop diameter of 4 to 20 μm was ejected in the gas phase direction, landed on the paper P, and an image was recorded.
Further, while feeding the paper P, the angle of the reflection mirror 236 is adjusted so that the laser beam 28 is irradiated to the position corresponding to the thin portion 230C, and the laser beam 28 is scanned in the arrow X direction. Thus, the ink droplet 16 having a drop diameter of 50 μm was ejected from the gas-liquid interface 34 corresponding to the thin portion 230C in the gas phase direction, landed on the paper P, and an image was recorded.

The ink droplets 16 having these three types of drop diameters were used.
Were discharged in the gas phase direction at a speed of 20 m / sec. Further, an image was recorded at a resolution of 1440 dpi (dot interval 17.64 μm) at the recording position of the paper P corresponding to the thick portion 230A.

In addition, the printing frequency is set to the conventional value (at most 20 kHz).
Since it can be much larger than z) and does not depend on the resolution of the nozzle, the scanning speed of the laser beam can be set high, and in addition, high resolution can be easily achieved. Also,
Since the ink droplet 16 is ejected at a speed of 20 m / sec regardless of the drop diameter, the ink droplet 16 is faster than before, and the ejection direction is stable due to the high ejection pressure. It was confirmed that it was hardly recognized.

[0133]

According to the present invention, while holding ink,
An ink holding member in which at least a part of a portion facing the recording medium is opened to form an ink ejection port, and a bubble is generated by irradiating a laser beam to the ink held by the ink holding member. Bubble generating means for discharging an ink droplet corresponding to image information from the ink discharge port with the generated shock wave, and a laser light irradiation position from the bubble generating means and a gas-liquid interface of the ink held by the ink holding member. And a distance changing unit that can change the distance, so that a nozzle like a conventional ink jet recording head is not required, and even if the ink discharge positions are arranged at a high density, nozzle clogging or discharge failure, image recording speed, etc. There is no inconvenience such as delay in image recording, and image recording is not interrupted halfway. As compared with a conventional laser addressing type bubble jet type recording head, the ejection direction is stable, and the landing position on the recording medium is constant even if there is air resistance or the like.
In addition, the need for an acoustic radiator, which is required for conventional inkjet recording heads that use acoustic waves, is eliminated, and it is possible to increase the density of ink ejection positions, enabling high-speed, high-density image recording. Becomes Furthermore, the drop diameter of the ink droplet can be changed by one ejection operation.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a basic configuration of an inkjet recording head according to a first embodiment of the present invention.

FIG. 2 is a perspective view illustrating a basic configuration of an inkjet recording head according to a second embodiment of the present invention.

FIG. 3 is a perspective view illustrating a basic configuration of an inkjet recording head according to a third embodiment of the present invention.

FIG. 4 is a perspective view illustrating a basic configuration of an inkjet recording head according to a fourth embodiment of the present invention.

FIG. 5 is a cross-sectional view illustrating a basic configuration of an inkjet recording head according to a fifth embodiment of the present invention.

FIG. 6 is a cross-sectional view illustrating a basic configuration of an inkjet recording head according to a sixth embodiment of the present invention.

FIG. 7 is a perspective view showing a configuration in which a laser beam is irradiated from the side of an ink holding member in the ink jet recording head of the present invention.

8 is a perspective view showing a configuration different from FIG. 7 in which a laser beam is irradiated from the side of the ink holding member in the ink jet recording head of the present invention.

9A and 9B show a configuration in which laser light is irradiated from the side of the ink holding member. FIG. 9A shows a case where the side wall is perpendicular to the gas-liquid interface, and FIG. 9B shows a case where the side wall is inclined with respect to the gas-liquid interface. Show the case.

FIG. 10 is a perspective view illustrating an inkjet recording head according to an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Ink jet recording head 12 Ink holding member 14 Ink ejection port 16 Ink droplet 18 Ink 24 Laser light generator (bubble generating means) 26 Condensing lens (bubble generating means) 28 Laser light 30 Laser light derivative (Distance changing means) 56 Optical fiber (Laser light derivative, distance changing means) 230 Laser light derivative (distance changing means) 314 Ink tank (distance changing means) 316 Tube (distance changing means) 318 Pump (distance changing means) 412 Partition (distance changing means) 414 Partition ( Distance changing means)

Continued on the front page (72) Inventor Yasufumi Suwabe 430 Sakai Nakaicho, Ashigarashimo-gun, Kanagawa Prefecture Green Tech Nakai Inside Fuji Xerox Co., Ltd. ) Inventor Yuji Suemitsu 430 Nakaicho, Nakai-cho, Ashigarakami-gun, Kanagawa Prefecture Inside Green X-Tech Fuji Xerox Co., Ltd. 430 Nakaicho, Ashigarakami-gun, Pref. Green Tech Nakai Fuji Xerox Co., Ltd. F-term (reference) 2C056 EA01 EA26 EA29 EB50 ED01 FA02 KC20 2C057 AF39 AF42 AF43 AF72 AG21 AG37 AG51 BA12 CA01

Claims (4)

[Claims] An ink holding member that holds ink and has an ink ejection opening formed by opening at least a part of a portion facing a recording medium; and applying a laser beam to the ink held by the ink holding member. A bubble generating means for irradiating to generate a bubble, and discharging ink droplets corresponding to image information from the ink discharge port with a shock wave generated by the bubble; a laser beam irradiation position from the bubble generating means and the ink holding member An ink jet recording head, comprising: a distance changing unit configured to change a distance between the ink held in the ink and the gas-liquid interface. 2. A laser light derivative provided on the ink holding member and guiding a laser beam from the bubble generating means to a predetermined position of the ink held on the ink holding member to set a position where a shock wave is generated. The ink jet recording head according to claim 1, further comprising: 3. The laser light derivative is a laser light transmitting member that is disposed between the ink held by the ink holding member and the bubble generating means and transmits laser light. 3. The ink jet recording head according to claim 2, wherein the thickness of the laser light transmitting member is partially changed. 4. An ink jet recording head according to claim 1, an ink supply device for supplying ink to an ink holding member of said ink jet recording head, and a laser beam from said bubble generating means. An ink jet recording apparatus comprising: a laser beam scanning device for scanning; and an image recording control device capable of controlling the ink jet recording head, the ink supply device, and the laser beam scanning device in accordance with image information. .