JPH06122201A - Inkjet printhead and inkjet printer - Google Patents

Abstract

(57) [Summary] [Structure] The ink ejection hole 13 for ejecting the ink 4 is arranged at the center of the transparent solvent ejection hole 12 for ejecting the transparent solvent 2, and both end faces are provided on the same plane to form each hole 12 , 13 and the transparent solvent 2 are mixed outside the holes. [Effect] It is possible to prevent unnecessary mixing of the ink and the transparent solvent during standby of the inkjet print head,
It is possible to realize halftone printing with uniform image quality during operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet print head and an ink jet printer for quantitatively mixing and ejecting ink in a transparent solvent.

[0002]

2. Description of the Related Art As a conventional two-liquid mixing type ink jet print head capable of halftone recording, an on-demand type thermal ink jet head which mixes two liquids on the upper surface of a heating element and two liquids which are mixed in an ejection portion. A continuous charge control inkjet head and the like are known.

[0003]

However, none of the conventional ink jet print heads described above has a complete function of preventing the two liquids from mixing when they are not necessary, and the two liquids are always in contact with each other in the mixing section. . For this reason, it is difficult to create a mixed liquid with an accurate mixing ratio at the start of the operation, and the mixed liquid that has been mixed in the mixing unit by that time has to be discharged once as a dummy. Further, since both liquids were in constant contact with each other, the respective liquids were likely to cause long-term chemical and physical reactions, and the characteristics of both liquids were likely to change. As a result, there is a problem in that density control tends to be unstable during printing, and printing quality is degraded.

The present invention has been made in view of the above circumstances, and ink jet printing capable of preventing unnecessary mixing of two liquids during standby and realizing halftone printing with uniform image quality during operation. An object is to provide a head and an inkjet printer.

[0005]

An ink jet print head according to a first aspect of the invention has an ink ejection hole 13 for ejecting an ink 4 and a transparent solvent ejection hole 1 for ejecting a transparent solvent 2.
2 are arranged in close proximity to each other, and the ink 4 and the transparent solvent 2 respectively discharged from the holes 12 and 13 are mixed outside the holes.

An ink jet print head according to a second aspect of the invention is characterized in that the ink ejection hole 13 and the transparent solvent ejection hole 12 are arranged coaxially.

An ink jet print head according to a third aspect of the present invention is characterized in that the ink discharge hole 13 is arranged at the center of the transparent solvent discharge hole 12 and both end surfaces are provided on the same plane.

In the ink jet print head according to the present invention, the ink ejection hole 13 is arranged at the center of the transparent solvent ejection hole 12, and the end face of the ink ejection hole 13 is provided inside the end face of the transparent solvent ejection hole 12. The inner periphery of the transparent solvent discharge hole 12 in the vicinity of the end face is coated with a substance 18 having low wettability with respect to the transparent solvent 2.

In the ink jet print head according to the fifth aspect, the end face of the ink ejection hole 13 is provided with the transparent solvent ejection hole 1
2 is projected from the end face.

An ink jet print head according to a sixth aspect of the present invention is characterized in that the ink ejection holes 13 and the transparent solvent ejection holes 12 are arranged adjacent to each other in parallel, and both end surfaces are provided on the same plane.

An ink jet print head according to a seventh aspect of the invention is characterized in that the ink ejection holes 13 and the transparent solvent ejection holes 12 are arranged adjacent to each other in parallel, and a step is provided on both end faces.

An ink jet print head according to an eighth aspect is characterized in that a plurality of transparent solvent ejection holes 12 are concentrically arranged on the outer periphery of the ink ejection hole 13.

An ink jet print head according to a ninth aspect of the invention is characterized in that the ink ejection holes 13 and the transparent solvent ejection holes 12 are arranged at a predetermined angle so that the respective tips of the ink ejection holes 13 and the transparent solvent ejection holes 12 abut each other.

An ink jet print head according to a tenth aspect of the invention is characterized in that the ink supply path 7 communicating with the ink ejection hole 13 is provided with an ink metering portion 5 for controlling the amount of ejected ink.

The ink jet print head according to the eleventh aspect of the present invention is characterized in that the ink metering portion 5 is provided with an electroosmotic membrane 16.

In the ink jet print head according to the twelfth aspect, the liquid chamber 3 in which the transparent solvent discharge hole 12 communicates,
An electrostrictive oscillator 11 that changes the volume of the liquid chamber is provided.

In the ink jet print head according to the thirteenth aspect, the liquid chamber 10 in which the transparent solvent discharge holes 111 communicate with each other.
9 is a side shooter type inkjet print head in which a heating element 110 for heating and vaporizing the transparent solvent 2 is provided.

In the ink jet print head according to the fourteenth aspect, the liquid chamber 10 in which the transparent solvent discharge holes 211 communicate with each other.
9 is an edge shooter type inkjet print head provided with a heating element 110 for heating and vaporizing the transparent solvent 2.

In the ink jet printer according to the fifteenth aspect, the head 51 is arranged so as to be movable in the axial direction of the drum 53 that rotates by rotating the print paper 52 as the printing object, and the head 51 rotates the drum 53. It is characterized in that a feed screw 54 is provided as a driving member that moves in conjunction with each other.

In the ink jet printer according to the sixteenth aspect, the head 51 is arranged so as to be movable in the axial direction of the drum 53 that rotates the print paper 52 and rotates, and the drum 53 rotates in conjunction with the movement of the head 51. It is characterized in that a motor 58 as a driving member is provided.

An ink jet printer according to a seventeenth aspect is characterized in that a plurality of heads 51 are arranged in a line in the axial direction of a drum 53 around which a print paper 52 is wound and rotated.

[0022]

In the ink jet print head according to any one of claims 1 to 9, the ink ejection hole 13 and the transparent solvent ejection hole 12 are independently arranged close to each other, and both liquids are mixed outside the hole during operation. , Both liquids do not mix when the head is not operating.

In the ink jet print head according to the tenth and eleventh aspects, since the ink metering portion 5 provided with the electroosmotic film 16 is provided in the ink supply path 7 communicating with the ink ejection hole 13, the electroosmotic film 16 is formed. By applying a DC voltage between the mesh electrodes inserted in the ink on both sides, the desired ink amount can be quantitatively moved from one side to the other side and supplied to the mixing nozzle section 8.

In the ink jet print head according to the twelfth aspect, since the electrostrictive vibrator 11 is provided in the liquid chamber 3 communicating with the transparent solvent discharge hole 12, a predetermined distance is provided between the electrodes 11a on both surfaces of the electrostrictive vibrator 11. By applying the voltage of 1, the electrostrictive oscillator 11 is displaced in the direction of decreasing the volume of the liquid chamber 3, and the transparent solvent 2 can be supplied to the mixing nozzle unit 8.

In the ink jet print head according to the thirteenth and fourteenth aspects, the liquid chamber 109 for the transparent solvent 2 is provided.
Since the heating element 110 is provided in the above, when a predetermined current is passed through the heating element 110, bubbles are generated in the transparent solvent 2 and the transparent solvent 2 can be supplied to the mixed ink ejection holes 116.

In the ink jet printer according to the fifteenth to seventeenth aspects, the print paper 5 as the printing object is used.
2 with respect to the drum 53 that rotates by winding the head 51
The feed and arrangement of can be changed to three types.

[0027]

Embodiments of the ink jet print head and ink jet printer of the present invention will be described below with reference to the drawings.

14 to 17 show examples of the construction of an ink jet printer equipped with the ink jet print head 51 according to this embodiment. FIG. 14 shows a configuration example of a drum rotation type. A print paper 52 as a material to be printed is wound around the outer periphery of a drum 53 and fixed at a predetermined position.
A feed screw 54 is provided on the outer periphery of the drum 53 in parallel with the drum axis direction, and the head 51 is screwed onto the feed screw 54. The head 51 is moved in the axial direction by the rotation of the feed screw 54. Also,
The drum 53 is rotationally driven by a motor 58 via a pulley 55, a belt 56, and a pulley 57. Further, the rotation of the feed screw 54 and the motor 58 and the drive of the head 51 are
The drive control unit 59 controls the drive based on the print data and the control signal 60.

In the above structure, when the drum 53 rotates, ink is ejected from the head 51 in synchronization with the rotation, and an image is formed on the print paper 52. Drum 5
When 3 has rotated once to complete printing of one row on the print paper 52 in the circumferential direction, the feed screw 54 rotates to move the head 51 by one pitch and print the next row. In this case, there is also a method of rotating the drum 53 and the feed screw 54 at the same time and gradually moving the head 51 while printing. Step feed is suitable for a multi-nozzle head or a configuration in which the same location is printed several times. However, when the number of single nozzles or multi-nozzles is small, the drum 53 and the feed screw 54 are operated at the same time. Spiral printing is performed while rotating.

FIG. 15 shows an example of a serial type configuration. In this case also, the structure is almost the same as that of the drum rotary type shown in FIG. 14, but the print paper 52 is not wound around the drum 53, and the paper pressure roller 61 provided in parallel to the axial direction causes the drum to rotate. It is pressure-bonded to 53. In this case, when the head 51 moves to print one line, the drum 53 is rotated by one line to print the next line. Head 51
The movement may be in the same direction or in the reciprocating direction.

FIG. 16 shows an example of a line type structure. In this case, instead of the serial type head 51 and the feed screw 54 shown in FIG. 15, a line head 62 having a large number of heads 51 arranged in a line is fixedly provided in the axial direction. In this configuration, the line head 62 simultaneously prints one line, and when the printing is completed, the drum 53 is rotated by one line to print the next line. In this case, print all lines at once, divide into multiple blocks, or
A method of alternately printing every other line is also conceivable.

FIG. 17 is a block diagram of the printing and control system. The signal 71 such as print data is a signal processing / control circuit 7.
2 is input to the head 74, is arranged in the printing order in the circuit 72, and is sent to the head 74 via the driver 73. The printing order differs depending on the configuration of the head and the printing unit and has a relationship with the input order of the print data. If necessary, the printing order is temporarily recorded in the memory 75 such as a line buffer memory or a one-screen memory and then taken out. A gradation signal and an ejection signal are output to the head 74.

When the number of nozzles is very large in a multi head, an IC is mounted on the head 74 to reduce the number of wirings connected to the head 74. Further, a correction circuit 76 is connected to the signal processing / control circuit 72, and performs γ correction, color correction in the case of color, variation correction of each head, and the like. It is general that the correction circuit 76 stores predetermined correction data in a ROM map type and retrieves it according to external conditions such as nozzle number, temperature, and input signal.

In the signal processing / control circuit 72, the CPU is a DSP.
Generally, software is used as a configuration, and the processed signals are sent to various control units 77. The various control units 77 perform controls such as driving of a motor that rotationally drives the drum 53 and the feed screw 54, synchronization, head cleaning, supply and discharge of the print paper 52. Further, it goes without saying that the signal 71 includes an operation unit signal other than print data and an external control signal.

1 and 2 show the construction of an embodiment of the ink jet print head of the present invention.

The present embodiment is a configuration example of a single head applied to a Kaiser type ink jet print head. In FIG. 1, the head 1 is provided with a liquid chamber 3 filled with a transparent solvent 2 and an ink quantification unit 5 for quantifying the ink 4 in parallel. A transparent solvent supply path 6 and an ink supply path 7 are provided at one ends of the liquid chamber 3 and the ink metering portion 5, respectively.
Are connected, and the other ends are connected to the mixing nozzle unit 8, respectively. A one-way valve 9 is provided in the transparent solvent supply path 6.
Is provided, and a flat plate type electrostrictive vibrator 11 is attached to the outer periphery of the liquid chamber 3 via a vibration plate 10. Further, the mixing nozzle portion 8 is concentrically provided with a cylindrical transparent solvent discharge hole 12 that communicates the liquid chamber 3 with the outside and a tubular ink discharge hole 13 that communicates the ink metering portion 5 with the outside. As shown in FIG. 2, transparent solvent nozzles 14 and ink nozzles 15 are formed at the tips of the ejection holes 12 and 13, respectively. The end faces of both nozzles 14 and 15 are arranged on the same plane.

The ink metering portion 5 is divided into two chambers by an electroosmotic membrane 16 formed of a porous diaphragm, one chamber 5a is connected to the ink supply passage 7, and the other chamber 5b is an ink ejection hole. It is connected to 13. Further, mesh electrodes (not shown) are provided on both surfaces of the electro-osmotic membrane 16, and the ink 4 permeates the electro-osmotic membrane 16 by applying a pulsed DC voltage between the mesh electrodes.
Move between b. The moving direction and the moving amount of the ink 4 can be accurately controlled by the polarity of the voltage and the amount of current applied between the electrodes.

On the other hand, the electrostrictive oscillator 11 has electrodes 11a adhered to both sides of a substance such as lead zirconate titanate which causes an electrostrictive phenomenon. By applying a predetermined voltage between the electrodes 11a, The electrostrictive oscillator 11 is polarized so that the volume of the liquid chamber 3 is displaced in the direction in which the phenomenon occurs.

Next, the operation of the above ink jet print head will be described with reference to FIGS. First, the transparent solvent 2 is supplied from the transparent solvent supply path 6, and the liquid chamber 3 and the transparent solvent discharge hole 12 are filled with the transparent solvent 2. Similarly, the ink 4 is supplied from the ink supply path 7 to fill the ink fixed amount portion 5 and the ink ejection hole 13 with the ink 4. At this time, make sure that no air remains inside. Figure 3 (a)
The state where the transparent solvent 2 and the ink 4 are filled in the mixing nozzle portion 8 is shown in FIG.

Next, at the mixing timing of the transparent solvent 2 and the ink 4, printing is started in step S101 shown in FIG. Next, in step S102, the ink metering unit 5 is controlled to supply the desired amount of the ink 4 supplied from the ink supply path 7 to the ink ejection holes 13 of the mixing nozzle unit 8. At the orifice of the ink nozzle 15, as shown in FIG. 3B, the amount of the supplied ink 4 is pushed out of the orifice. The ink 4 pushed out at this time does not jump out from the ink nozzle 15 and remains in a spherical shape 4a at the exit thereof. This spherical state is determined by the contact angle between the ink 4 and the ink nozzle 15, the viscosity of the ink 4, and the surface tension.

Next, in step S103 shown in FIG. 4, when a predetermined voltage is applied between the electrodes 11a of the electrostrictive oscillator 11, the electrostrictive oscillator 11 is displaced and the volume in the liquid chamber 3 is reduced. The transparent solvent 2 is discharged to the outside of the transparent solvent nozzle 14 as shown in FIG. At this time, the ink sphere 4a pushed out from the adjacent ink nozzle 15 and the transparent solvent 2a in the discharging process come into contact with each other, and the two liquids try to be integrated by the surface tension. As a result, as shown in FIG. 3 (d), the ink sphere 4a is drawn into the movement of the transparent solvent 2a, and the two are integrated into a mixed liquid 17, and the mixed liquid 17 is mixed as shown in FIG. 3 (e). Discharge from the nozzle portion 8. Then, the ink 4 and the transparent solvent 4 are mixed with each other, and finally fly as a mixed liquid 17 having a desired concentration and fly, and adhere to a recording paper (not shown).

When the transparent solvent 2 is discharged, the liquid chamber 3
The pressure and volume reduction applied to the transparent solvent supply passage 6 are efficiently transmitted to the mixing nozzle portion 8 without affecting the supply passage 6 by the one-way valve 9 provided in the transparent solvent supply passage 6. Electrostrictive oscillator 11
When the displacement of (1) is returned to the original position, the transparent solvent 2 is supplied from the transparent solvent supply passage 6 into the liquid chamber 3 via the one-way valve 9.

Next, in step S104 shown in FIG. 4, it is determined whether or not the next dot is printed, and if there is, the process returns to step S102 and the above operation is repeated. If there is no next dot printing, the process returns to step S101 and waits.

According to the present embodiment, when the head 1 is not performing the printing operation, the ink 4 in the ink nozzle 15 and the transparent solvent 2 in the transparent solvent nozzle 14 are stored in the respective nozzles 15, 14. The respective liquid surfaces remain inside the ends of both nozzles 15 and 14 due to surface tension. Therefore, both liquids 2 and 4 never mix. As a result, long-term contact between the two liquids 2 and 4 can be prevented, so that the chemical and physical reaction of the two liquids 2 and 4 can be completely prevented, and the concentration control during printing can be reliably performed. Thus, it is possible to realize halftone printing with uniform image quality.

FIG. 5 shows a modified example of the mixing nozzle portion 8, and FIG. 6 shows the discharge operation of the respective transparent solvent 2 and ink 4. In these figures, the portions corresponding to those of the embodiment shown in FIGS. 2 and 3 are designated by the same reference numerals, and the description thereof will be omitted as appropriate.

The mixing nozzle section 8 shown in FIG.
The tip of the ink nozzle 15 of the mixing nozzle portion 8 shown in FIG. 2 is located inside the tip of the transparent solvent nozzle 14, and the transparent solvent 2 is wetted in a range outside the ink nozzle 15 on the inner circumference of the tip of the transparent solvent nozzle 14. A substance 18 having a low contact property and a large contact angle was coated. According to this modification,
Since the transparent solvent 2 is inside the tip of the ink nozzle 15 when the head 1 is not performing a printing operation, the transparent solvent 2 and the ink 4 do not spontaneously mix.

The mixing nozzle section 8 shown in FIG.
This is an example in which the tip of the ink nozzle 15 of the mixing nozzle portion 8 shown in FIG.

In the mixing nozzle portion 8 shown in FIG. 5C, the ink ejection holes 13 and the transparent solvent ejection holes 12 are provided adjacent to each other in parallel, and the end faces of the ink nozzle 15 and the transparent solvent nozzle 14 are the same. It is an example configured to be located on a plane.

The mixing nozzle section 8 shown in FIG.
This is an example in which the tips of the ink nozzle 15 and the transparent solvent nozzle 14 shown in (c) are obliquely cut so that the tip of the ink nozzle 15 protrudes from the tip of the transparent solvent nozzle 14.

In the mixing nozzle section 8 shown in FIG. 5 (e), the ink ejection hole 13 and the transparent solvent ejection hole 12 are provided with an angle θ, and the tips of the ink nozzle 15 and the transparent solvent nozzle 14 are opposed to each other. This is an example of the above.

In the mixing nozzle portion 8 shown in FIG. 5 (f), an ink discharge hole 13 is provided at the center, a plurality of transparent solvent discharge holes 12 are arranged in parallel around the ink discharge hole 13, and the ink nozzle 15 and In this example, the end face of the transparent solvent nozzle 14 is located on the same plane.

6A, 6B, 6C, 6D,
(E) and (f) are shown in FIGS.
Mixing nozzle section 8 shown in (c), (d), (e), and (f)
FIG. 11 is an explanatory view showing the discharge operation of the modified example, but since the operation is almost the same as the operation of the embodiment shown in FIG. 3, the description thereof will be omitted.

Also according to each modification shown in FIG.
The same effect as that of the embodiment shown in can be obtained.

In the embodiment shown in FIG. 1, the Kaiser type ink jet print head 1 using the flat plate type electrostrictive vibrator 11 has been described, but as shown in FIG. Two liquid chambers 3 a and 3 b are formed by using a Gould type inkjet print head formed in a cylindrical shape surrounding the outer periphery or a flat plate type electrostrictive vibrator 11 as shown in FIG.
The same effect can be obtained by applying it to the step-type inkjet print head configured as above.

In each of the above embodiments, the case where the electrostrictive vibrator 11 is used as the means for ejecting the transparent solvent 2 has been described, but it may be applied to an ink nozzle of a thermal ink jet type ink jet print.

There are two types of thermal ink jet print heads, an edge shooter type thermal ink jet print head and a side shooter type thermal ink jet print head, depending on the direction of the nozzle frontage.

9 and 11 show examples of the construction of the edge shooter type and side shooter type thermal ink jet print heads, respectively. The basic principle of ink ejection is exactly the same in either method. In FIGS. 9 and 11, a heater 23 is provided on a substrate 21 with an insulating film 22 such as SiO ₂ interposed therebetween. A pair of A on the heater 23
1 electrodes 24 and 25 are provided so as to face each other, and the heater 2
3 and the upper surfaces of the electrodes 24 and 25 are three layers of protective films 26 and 2
It is coated with 7, 28. Further, an opening 28a is formed at a position where the electrodes 24 and 25 are opposed to each other in the protective film 28 made of polyimide, which is the uppermost layer.
An orifice plate 29 is provided on the upper part of 8. Then, the ink 31 is supplied to the liquid chamber 30 formed in the orifice plate 29 from an ink supply path (not shown).

Here, in the edge shooter type head shown in FIG. 9, the liquid chamber 30 is opened in a direction parallel to the heater 23, and in the side shooter type head shown in FIG. 11, the heater 2 is used.
A liquid chamber 30 is opened in a direction perpendicular to 3, forming nozzles 32 and 33, respectively. In the side shooter type head, the protective film has two layers 26 and 28.

In the edge shooter type thermal ink jet print head constructed as described above, the heater 23
When a predetermined voltage pulse is applied for a certain period of time to FIG.
As shown in, a nuclear bubble 41 is generated on the surface of the heater 23. The nuclear bubbles 41 are combined as shown in FIG.
2, and the film bubbles 42 grow into a bubble 43 by adiabatic expansion as shown in (c). Next, the heater 2
When the voltage is not applied to No. 3, the bubble 43 is shrunk by the heat of the surrounding ink 31 as shown in (d) and disappears as shown in (e). Then, due to the ejection force of the film boiling phenomenon that occurs in the processes of (c), (d), and (e), the ink 31 becomes the ink particles 31a and is ejected from the nozzle 32 to the outside.

Also in the side shooter type thermal ink jet print head shown in FIG. 11, the ink particles 31a are ejected by the same action as shown in FIG. In FIG. 12, a plurality of liquid chambers 30 are provided in parallel with the orifice plate 29, and a common ink supply path 44 is provided.
The ink 31 is supplied from. In addition, the ink supply path 44
A barrier 45 for partitioning each liquid chamber 30 is provided therein.

FIG. 13 shows an example in which the side shooter type thermal ink jet print head shown in FIG. 11 is used as a two-liquid mixing chamber. That is, the liquid chamber 30 shown in FIG.
The ink metering portion 5 was provided on the upper part of the nozzle 9, and the ink ejection hole 13 was opened to the outer circumference of the nozzle 33. This embodiment is shown in FIG.
The mixing nozzle section 8 shown in (4) is applied to a side shooter type inkjet print head.

In each of the above-described embodiments, the case of a single head has been described. However, a single color multi-head having a plurality of heads, a multi-color color head in which the ink supply chamber is divided into the number of colors to make multiple colors, or a single-color multi-head. The same effect can be obtained by applying it to a multicolor multihead in which a plurality of heads corresponding to the number of colors are provided.

Next, an inkjet printer in which a plurality of side shooter type thermal ink jet print heads or edge shooter type thermal ink jet print heads as described above are arranged will be described.

18 to 20 are a schematic overall view, a horizontal cross-sectional view and a vertical cross-sectional view of a side shooter type thermal ink jet print head having a multi-type structure.

The side shooter type thermal ink jet print head comprises an ink lead-out section 1, a transparent solvent ejecting section 2 and an ink quantitative pressure feeding section 3. The ink 4 is filled in the ink metering units 112 and 112 ′ which are partitioned into two by the electroosmotic membrane 113 in the ink metering pressure-feeding unit 103. Mesh electrodes 114 and 114 'capable of transmitting ink are provided on the front and back of the electro-osmotic membrane 113.
Is fixed.

On the other hand, in the transparent solvent discharge part 2, the transparent solution 2 is introduced from a transparent solution tank (not shown) and filled in the liquid chamber 109 and the common liquid chamber 109 '. Further, a heater 110 is provided below the liquid chamber 109.
The transparent solvent 2 extruded from the transparent solvent discharge hole 111,
The ink 4 pushed out from the ink ejection hole 106 is mixed in the mixed ink ejection hole 116 in the ink lead-out section 1.

Ink 4 is replaced with ink quantification units 112 and 11
The electroosmosis in which a constant pressure is fed from 2'is the same as in the embodiment of FIGS. 1 and 2, and the description thereof is omitted here.

It is the pulse width of the voltage pulse applied to the mesh electrode 114 'by electroosmosis that controls the amount of the ink 4, and the voltage pulse for pushing out the ink 4 and the voltage pulse for ejecting the transparent solvent 2 are predetermined. Given at the timing. Therefore, when the amount of the ejected ink 4 is large, it may come into contact with the transparent solvent 2 before being ejected. At this time, since the ink 4 does not diffuse and mix into the transparent solvent 2, as soon as a predetermined amount of the ink 4 is pushed out, the ink 4 is ejected together with the transparent solvent 2.

The timing at which the electroosmotic voltage pulse for ejecting the ink 4 and the ejection voltage pulse are generated by electroosmosis is as shown in FIG. The voltage pulse width t _ei of electroosmosis is t depending on the amount of the ink 4 mixed.
It changes like _e1 , t _e2 , and t _e3 . The interval T for ejecting the ink 4, the width t _p of the ejection voltage pulse, and the time t _d from the end of the electroosmotic voltage pulse to the generation of the ejection voltage pulse are constant. Therefore, the density of the print dots, that is, the amount of the ink 4 is adjusted at the timing of generating the electroosmotic voltage pulse.

The voltage pulse for electroosmosis and the actual movement of the ink 4 are not completely synchronized, and the ejection of the ink 4 is delayed. This delay, or responsiveness, changes depending on the characteristics of the head and ink. The value of the time t _d is determined by the delay time and is set to be slightly longer than the delay time.

The interval t _x from the stop of the discharge voltage pulse to the generation of the electroosmotic voltage pulse changes depending on the timing at which the electroosmotic voltage pulse is generated. The transparent solvent 2 is refilled during this time, but the time required for refilling the transparent solvent 2 depends on the viscosity and surface tension of the ink 4, the diameter of the mixed ink ejection hole, and the like, so the above interval t _x
Is set to be longer than the refilling time of the transparent solvent 2.

The discharge operation of the transparent solvent 2 and the ink 4 of the side shooter type thermal ink jet print head is shown in FIG.
Shown in. 21A shows the ejection standby state, and the ink 4 quantified by electroosmosis is the ink ejection hole 106.
It is pushed out from and is in a state of excitement. Transparent solvent 2
Since the surface tension and the external pressure are in equilibrium, the transparent solvent ejection hole 111 forms the meniscus surface 115. The transparent solvent ejection hole 111 has a smaller diameter than the mixed ink ejection hole 116, and a liquid repellent treatment with polytetrafluoroethylene or the like is performed in the vicinity thereof. Therefore, in the standby state, the transparent solvent 2 does not reach the mixed ink ejection holes 116 due to the capillary phenomenon.

In FIG. 21B, the transparent solvent 2 is heated because the heater 110 is heated and the surface temperature thereof is rapidly increased.
The boiling phenomenon starts at the interface between the heater 110 and the heater 110, and minute bubbles 117 are scattered.

When the transparent solvent 2 heated rapidly is vaporized instantly, a so-called film boiling phenomenon occurs as shown in FIG. 21 (c). Since the pressure in the liquid chamber 109 rises by the amount of growth of the bubble 117, the equilibrium state with the external force on the meniscus surface 115 is broken and the column of the transparent solvent begins to grow from the transparent solvent ejection hole 111. Therefore, the ink 4 pushed out from the ink ejection hole 106 and the transparent solvent 2 which has started to grow are brought into contact with each other to form the mixed ink column 118, and the growth is continued.

After this, as shown in FIG. 21D, the bubble 117 is in a state of maximum growth, and the volume of the transparent solvent 2 corresponding to the volume of the bubble 117 is added with the ink 4 mixed in a fixed amount. The mixed ink of is ejected from the mixed ink ejection hole 116. At this time, no current is flowing through the heater 110, and the surface temperature of the heater 110 is decreasing. The volume of the bubble 117 reaches its maximum slightly after the timing of cutting the electric pulse to the heater 110.

Next, the bubble 1 as shown in FIG.
17 is cooled by the transparent solvent 2 or the like and is in a state in which it begins to shrink. At the front end of the mixed ink column 118, it moves forward at the pushing speed, and at the rear end, the bubbles 117 contract and the liquid chamber 1
As the internal pressure of 09 decreases, the mixed ink ejection holes 1
The transparent solvent 2 flows backward from 16 to the transparent solvent ejection hole 111, and a constriction occurs in the mixed ink column 118. Since almost all of the ink 4 is present at the leading end of the mixed ink column 118, the trailing end is almost only the transparent solvent 2. Therefore, the liquid chamber 109
The ink 4 does not flow back and mixes with the transparent solvent 2. Further, since it is the transparent solvent 2 that is heated, and the transparent solvent does not contain a dye, the surface of the heater 110, such as an inkjet print head that utilizes the conventional film boiling phenomenon of ink for ejecting mixed ink droplets, can be used. There is no sticking of foreign matter due to thermal decomposition of the dye, so-called charring.

All of the ink 4 mixed in the transparent solvent 2 is contained in the flying mixed ink droplets and does not remain in the transparent solvent 2 drawn into the liquid chamber 109, but is extruded by the force of discharging the transparent solvent 2. Since it is possible to sufficiently fly to the printed material together with the generated ink 4, the amount of the transparent medium 2 to be ejected is a certain amount or more with respect to the amount of the mixed ink 4.

The mixing ratio for the ink 4 not to mix with the transparent medium 2 in the liquid chamber 109 and to fly sufficiently is 50% or less with respect to the transparent medium 2, but may be about 30%. desirable. Therefore, the ink 4 should have a sufficient density to obtain a sufficient maximum density, and the ink 4 contains a dye so that the printing density of the mixed ink is 2 or more in reflection density.

The size of the mixed ink droplets varies depending on the amount of the ink 4 mixed. Therefore, the gradation of the image to be printed is controlled by the density of the mixed ink droplets and the area of the print dots. For example, when the mixing ratio of the ink 4 at the maximum density is 30% by volume, the minimum density, that is, the volume ratio of the mixed ink droplets ejected when the ink 4 is not mixed at all and the maximum density is It is 7:10. Further, the volume of the mixed ink droplets and the print dot diameter are almost proportional to each other. Therefore, the amount of the ink 4 to be mixed is controlled in consideration of the change in the print dot diameter so as to obtain a desired print density.

Further, the bubble 117 contracts, and the liquid chamber 109
When the transparent solvent 2 comes into contact with the surface of the heater 110 on the side and the cooling progresses, the external pressure in the transparent solvent discharge hole 111 becomes higher than the internal pressure of the liquid chamber 109. Therefore, as shown in FIG. The surface 115 enters the liquid chamber 109.

After that, as shown in FIG. 21G, the transparent solvent 2 is refilled by the capillary phenomenon, and the state where the meniscus surface 115 is formed in the transparent solvent discharge hole 111 is restored. At this time, the bubble 117 has completely disappeared.

As the ink 4, a material having an electroosmotic property with respect to the electroosmotic film 113 is used. Both water-based and non-water-based ones can be used, but in the water-based ones, the driving voltage must be set below the decomposition voltage (around 1V) in order to cause electrolysis, so that the permeation speed cannot be taken,
Not preferable.

As the transparent solvent 2, a solvent having compatibility with the ink is used. For example, for the ink having the above structure, chlorooctane and a mixture thereof with a wetting agent, a vehicle agent and the like can be used. When a compatible solvent is used as the transparent solvent, the ink is well diffused in the transparent solvent, so that the concentration of the mixed ink droplets becomes uniform. Therefore, the image is represented in gradation by the density of dots, and a higher quality image can be obtained. However, since the size of the mixed ink droplets changes depending on the amount of ink mixed, it is necessary to perform gradation control in consideration of this.

Further, as the transparent solvent, water and a solvent having incompatibility obtained by adding a wetting agent, a vehicle agent and the like thereto can also be used. When a non-compatible solvent is used as the transparent solvent, the diffusion of the ink into the transparent solvent is incomplete, so the transparent solvent serves as a carrier for carrying the ink to the non-printed material. Therefore, the image becomes close to the one expressed in gradation by the change in the size of the ink dot, that is, the area. However, since the ink does not mix with the transparent solvent, it is less likely that the ink will mix into the liquid chamber when the ink is pushed out to the mixed ink ejection hole.

For the electroosmotic membrane 113, for example, a microporous membrane filter is used. As the material, celluloses such as nitrocellulose, acetylcellulose, regenerated cellulose, plastics such as polytetrafluoroethylene, polycarbonate, polyamide, polyethylene, glass, ceramics such as alumina can be used. It is necessary for the ink to be electroosmotic without swelling or attacking. For example, when nitrocellulose is used as the electroosmotic membrane, for example, chlorooctane is used as a solvent, and 1 to 5% by weight of a quaternary ammonium salt of dodecylbenzenesulfonic acid is dissolved as an electrolyte, and a dye, a wetting agent, and a vehicle are further dissolved. Inks to which agents and the like have been added can be used.

In addition, the mesh electrodes 114 and 11
4'is preferably an inert metal that does not react with a substance in the ink, for example, a thickness of 50 μm, pitch 1
After nickel plating on the iron mesh of 00μm,
Those plated with platinum or gold are suitable. Alternatively, for example, gold may be vapor-deposited directly on the front and back of the electro-osmotic membrane 113, and this may be used as an electrode.

The head body must have solvent resistance to the solvent used for the ink or the transparent solvent. For example, plastics such as polyethylene, polypropylene and polytetrafluoroethylene, glass, ceramic materials such as alumina, stainless steel, And a metal such as nickel.

23 to 25 are a schematic general view, a horizontal sectional view and a vertical sectional view of a multi-edged edge shooter type thermal ink jet print head.

The edge shooter type thermal ink jet print head, like the side shooter type thermal ink jet print head, comprises an ink lead-out section 1, a transparent solvent ejection section 2 and an ink fixed amount pressure feed section 3. The ink 4 is placed in the ink metering units 112 and 112 ′ which are partitioned into two by the electroosmotic membrane 113 in the ink metering pressure-feeding unit 103.
Is satisfied. On the front and back of the electro-osmosis membrane 113, mesh electrodes 114 and 1 capable of transmitting ink are provided.
14 'is fixed.

On the other hand, in the transparent solvent discharge part 2, the transparent solution 2 is guided from the transparent solution tank (not shown) to the transparent solvent supply passage 108 and filled in the liquid chamber 109. Further, the ink 4 is guided to the ink supply path 105 from an ink tank (not shown), and the ink quantification units 112 and 112 ′ are provided.
Sent to. A heater 110 is provided below the liquid chamber 109. The transparent solvent 2 extruded from the transparent solvent ejection hole 111 and the ink 4 extruded from the ink ejection hole 116 are mixed in the mixed ink ejection hole 116 in the ink outlet 1. The liquid chamber 109 is divided by a barrier 130. This prevents interference between the adjacent liquid chambers 109 when bubbles are generated, and the pressure of the bubbles is concentrated in the direction of the transparent solvent ejection hole 111. The barrier 130 also serves as a spacer that keeps the distance from the heater 110 to the transparent solvent ejection hole 111 constant.

Ink 4 is replaced with ink quantification units 112 and 11
The electroosmosis in which a constant pressure is fed from 2'is the same as in the embodiment of FIGS. 1 and 2, and the description thereof is omitted here.

The amount of the ink 4 by the edge shooter type thermal ink jet print head is controlled and ejected by the electroosmosis as described above. The timing at which the electroosmotic voltage pulse for pushing out the ink 4 and the ejection voltage pulse are generated by electroosmosis is the same as in the embodiment of the side shooter type thermal inkjet printhead using FIG.

The discharge operation of the transparent solvent 2 and the ink 4 of the edge shooter type thermal ink jet print head is shown in FIG.
Shown in. The discharging operation is the same as the discharging operation of the transparent medium 2 and the ink 4 of the side shooter type thermal inkjet print head of the thermal inkjet system, and FIG. 26A shows the standby state for discharging and was quantified by electroosmosis. The ink 4 is in a state of being extruded from the ink ejection hole 106 and rising.

In FIG. 21B, the transparent solvent 2 is heated because the heater 110 is heated and the surface temperature thereof is rapidly increased.
The boiling phenomenon starts at the interface between the heater 110 and the heater 110, and minute bubbles 117 are scattered.

When the rapidly heated transparent solvent 2 vaporizes instantly, a so-called film boiling phenomenon occurs as shown in FIG. 21 (c). Therefore, the ink 4 pushed out from the ink ejection hole 106 and the transparent solvent 2 which has started to grow are brought into contact with each other to form the mixed ink column 118, and the growth is continued.

After this, as shown in FIG. 21D, the bubble 117 is in the state of maximum growth, and the volume of the transparent solvent 2 corresponding to the volume of the bubble 117 plus the ink 4 quantitatively mixed therein is added. The mixed ink is pushed out from the mixed ink ejection hole 116.

Next, the bubble 1 as shown in FIG.
17 is cooled by the transparent solvent 2 or the like and is in a state in which it begins to shrink. Since the transparent solvent 2 is heated, and the transparent solvent does not contain the dye, the dye on the surface of the heater 110 can be changed like the ink jet print head that utilizes the film boiling phenomenon of the conventional ink to eject the mixed ink droplets. No foreign matter is attached due to thermal decomposition, so-called charring.

Further, the bubble 117 contracts and the liquid chamber 109
When the transparent solvent 2 comes into contact with the surface of the heater 110 on the side and the cooling progresses, the external pressure in the transparent solvent discharge hole 111 becomes higher than the internal pressure of the liquid chamber 109. Therefore, as shown in (f) of FIG. The surface 115 enters the liquid chamber 109.

After that, as shown in FIG. 21G, the transparent solvent 2 is refilled by the capillary phenomenon, and the state where the meniscus surface 115 is formed in the transparent solvent discharge hole 111 is restored. At this time, the bubble 117 has completely disappeared.

A description of the construction and the printing and control system of an ink jet printer equipped with the above-described multi-edge edge shooter type thermal ink jet print head or side shooter type thermal ink jet print head will be given.
Since the contents are the same as those described with reference to FIGS. 14 to 17, description thereof will be omitted here.

The control method of the multi-headed head is shown in the block diagram of FIG. The digital halftone data is supplied to the serial / parallel conversion circuit 121 by the signal processing control circuit 72 in FIG. 17, and is sent from there to each ink metering unit driver 123.

At the print timing, a print trigger is output from the signal processing control circuit 72, the timing control circuit 122 detects this, and the ink fixed amount enable signal is sent to the ink fixed amount driver 12 at a predetermined timing.
3, the transparent solvent ejecting unit Enable signal is output to the transparent solution ejecting unit driver 124. The respective Enable signals are output at the timings shown in FIG.

In response to the ink quantitative section Enable signal, each ink quantitative section driver 123 controls the corresponding ink quantitative section 125, whereby a predetermined amount of ink is pressure-fed from the ink ejection holes 106 of a plurality of heads. It

On the other hand, the transparent solvent ejecting unit Enable which has a delay from the ink fixed amount Enable signal by a predetermined time.
The transparent solvent ejection unit driver 124 controls each transparent solvent ejection unit 126 according to the e signal. As a result, the transparent solvent is ejected while being mixed with the ink.

[0105]

As described above, according to the ink jet print head of the first to ninth aspects, the ink ejection holes and the transparent solvent ejection holes are independently arranged close to each other, and the holes are formed during operation. Since both liquids are mixed outside, mixing of both liquids when the head is not operating can be prevented. As a result, long-term contact between both liquids can be prevented, chemical and physical reactions between both liquids can be completely prevented, density control during printing can be reliably performed, and uniform image quality can be achieved. Halftone printing can be realized.

Further, according to the ink jet print head of the tenth and eleventh aspects, since the ink supply path is provided with the ink metering portion provided with the electroosmotic film, the desired ink quantity is metered to the mixing nozzle part. Can be supplied.

Further, according to the ink jet print head of the twelfth aspect, since the electrostrictive vibrator is provided in the liquid chamber, the transparent solvent can be easily supplied to the mixing nozzle section.

Further, according to the ink jet print head of the thirteenth and fourteenth aspects, since the heating element is provided in the liquid chamber, the transparent solvent can be easily supplied to the mixed ink ejection hole.

According to the ink jet printer of the fifteenth to seventeenth aspects, it is possible to change the feed and arrangement of the head to three types with respect to the drum that winds and rotates the printing material.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the configuration of an embodiment of an inkjet printhead of the present invention.

FIG. 2 is an enlarged cross-sectional view showing a configuration of a mixing nozzle section of FIG.

FIG. 3 is an explanatory diagram showing an ejection operation of the ink and the transparent solvent of the embodiment shown in FIG.

FIG. 4 is a flowchart illustrating the operation of the inkjet print head according to the embodiment shown in FIG.

FIG. 5 is an explanatory diagram showing a configuration of a modified example of the mixing nozzle portion of the inkjet print head of the present invention.

6A and 6B are explanatory views showing the operation of ejecting the ink and the transparent solvent from the mixing nozzle section shown in FIG.

FIG. 7 is a vertical cross-sectional view showing a schematic configuration of an example of a groove type inkjet print head.

FIG. 8 is a vertical cross-sectional view showing a schematic configuration of an example of a step type inkjet print head.

FIG. 9 is a vertical cross-sectional view showing the configuration of an example of an edge shooter type thermal inkjet printhead.

FIG. 10 is an explanatory diagram showing a droplet forming process by the head shown in FIG.

FIG. 11 is a vertical cross-sectional view showing a configuration of an example of a side shooter type thermal inkjet printhead in a direction perpendicular to the multi-direction.

FIG. 12 is a vertical cross-sectional view taken along the multi-direction of FIG.

FIG. 13 is a vertical cross-sectional view showing the configuration of an example of a two-liquid mixing sideshooter type thermal inkjet printhead.

FIG. 14 is an explanatory diagram showing a configuration of an example of a drum rotation type inkjet printer.

FIG. 15 is an explanatory diagram showing a configuration of an example of a serial type inkjet printer.

FIG. 16 is an explanatory diagram showing a configuration of an example of a line type inkjet printer.

FIG. 17 is a block diagram showing a configuration of an example of a signal processing and control system of the inkjet printer.

FIG. 18 is an overall view showing a configuration of an example of a side shooter type thermal ink jet print head which is multi-typed.

19 is a vertical cross-sectional view of the inkjet print head shown in FIG. 18, taken along the multi-direction.

20 is a vertical cross-sectional view of the inkjet print head shown in FIG. 18 in a direction perpendicular to the multi-direction.

FIG. 21 is an explanatory diagram showing an ejection operation of ink and a transparent solvent of the inkjet print head shown in FIG. 18.

22 is a diagram showing the timing of drive voltage pulses of the inkjet print head shown in FIG.

FIG. 23 is an overall view showing the configuration of an example of a multi-edged edge shooter type thermal inkjet printhead.

24 is a vertical cross-sectional view of the inkjet print head shown in FIG. 23 in a direction perpendicular to the multi-direction.

FIG. 25 is a vertical cross-sectional view of the inkjet print head shown in FIG. 23, taken along the multi-direction.

FIG. 26 is an explanatory diagram showing an ejection operation of ink and a transparent solvent of the inkjet print head shown in FIG. 23.

FIG. 27 is a diagram schematically showing a driving operation of the thermal inkjet printhead.

[Explanation of symbols]

 1, 51 ・ ・ ・ ・ ・ ・ Print head 2 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Transparent solvent 3,109 ・ ・ ・ ・ ・ ・ Liquid chamber 4 ・ ・ ・・ ・ ・ Ink 5,112,112 '・ ・ ・ Ink fixed amount section 7,105 ・ ・ ・ ・ ・ ・ Ink supply path 11 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Electrostrictive vibrator 12, 111 ··· Transparent solvent discharge hole 13, 106 ··· Ink discharge hole 16, 113 ··· · Electro-osmotic membrane 18 ··· Material 52 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Printed paper (printed material) 53 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Drum 54 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Feed screw (driving member) 58: Motor (driving member) 110: Heater

Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location B41J 2/045 2/055 2/205 8306-2C B41J 3/04 102 Z 9012-2C 103 A 9012-2C 103 X (72) Inventor Masayuki Sato, 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) In-house Masao Shinya 6-7-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation

Claims (17)

[Claims] 1. An ink ejection hole for ejecting ink and a transparent solvent ejection hole for ejecting a transparent solvent are arranged in proximity to each other, and the ink and the transparent solvent ejected from the respective holes are outside the hole. An inkjet printhead characterized by mixing. 2. The ink jet print head according to claim 1, wherein the ink ejection hole and the transparent solvent ejection hole are coaxially arranged. 3. The ink jet print head according to claim 2, wherein the ink discharge hole is arranged at the center of the transparent solvent discharge hole, and both end surfaces are provided on the same plane. 4. The ink ejection hole is arranged in the center of the transparent solvent ejection hole, the end face of the ink ejection hole is provided inside the end face of the transparent solvent ejection hole, and the end face of the transparent solvent ejection hole is near the end face. The ink jet print head according to claim 2, wherein the inner circumference of the ink is coated with a substance having low wettability with respect to the transparent solvent. 5. The ink discharge hole is arranged in the center of the transparent solvent discharge hole, and the end face of the ink discharge hole is projected from the end face of the transparent solvent discharge hole. Inkjet printhead. 6. The ink jet print head according to claim 2, wherein the ink ejection hole and the transparent solvent ejection hole are arranged adjacent to each other in parallel, and both end surfaces are provided on the same plane. 7. The ink jet print head according to claim 1, wherein the ink ejection hole and the transparent solvent ejection hole are arranged adjacent to each other in parallel, and a step is provided on both end faces. 8. The ink jet print head according to claim 1, wherein a plurality of the transparent solvent ejection holes are concentrically arranged on the outer periphery of the ink ejection hole. 9. The ink jet print head according to claim 1, wherein the ink ejection holes and the transparent solvent ejection holes are arranged such that their respective tips are abutted against each other to form a predetermined angle. 10. The ink jet print head according to claim 1, further comprising an ink metering unit for controlling an amount of ejected ink, which is provided in an ink supply path communicating with the ink ejection hole. 11. The inkjet printhead of claim 10, wherein the ink metering unit includes an electroosmotic membrane. 12. The ink jet print head according to claim 1, wherein an electrostrictive vibrator for changing the volume of the liquid chamber is provided in the liquid chamber communicating with the transparent solvent discharge hole. 13. The ink jet print head according to claim 1, wherein a heating element for heating and vaporizing the transparent solvent is provided in a liquid chamber communicating with the transparent solvent discharge hole. Inkjet printhead. 14. The ink jet print head according to claim 1, wherein a heating element for heating and vaporizing the transparent solvent is provided in a liquid chamber communicating with the transparent solvent discharge hole. Inkjet printhead. 15. The printing apparatus according to claim 1, wherein the printing material is wound and movable in an axial direction of a rotating drum.
An inkjet printer, wherein the inkjet print head according to the item 1 is arranged, and a drive member for moving the head in association with rotation of the drum is provided. 16. The ink jet print head according to claim 1, wherein the inkjet print head is arranged so as to be movable in an axial direction of the drum that winds and rotates the object to be printed, and the drum is mounted on the head. An inkjet printer having a driving member that rotates in association with movement. 17. The inkjet print head according to claim 1, wherein the inkjet print heads are arranged in a line in the axial direction of the drum that winds and rotates the printing object. Inkjet printer to do.