JPH1016221A - Liquid ejection head and liquid ejection device - Google Patents

Abstract

(57) [Problem] To provide a liquid ejection head and a liquid ejection device that enable high-quality recording. SOLUTION: Two liquid ejection heaters 2a, 2b are provided corresponding to one nozzle 104. Heater 2
a and 2b are independently driven for each type, so that the liquid is Vd1
A first mode in which the liquid is discharged at a volume of
And a second mode in which the liquid is discharged with a higher definition than the first mode with a volume of Vd2 smaller than 1. In the first mode, voltage drive pulses under the same conditions are applied to both heaters 2a and 2b at the same time. In the second mode, a driving pulse is applied to one of the heaters 2a or 2b under a condition different from the driving condition in the first mode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet head as a liquid discharge head used in a copier, a facsimile, a word processor, a printer as an output terminal of a host computer, a video printer, etc., and an ink jet head including a tank. The present invention relates to a head cartridge and an ink jet apparatus as a liquid ejection apparatus, and more particularly to a liquid ejection head having a base on which an electrothermal conversion element that generates heat energy as energy for ejecting ink is formed, and a liquid ejection apparatus using the head.

The term "recording" used herein includes printing (inking) on all ink supports to which ink is applied, such as cloth, thread, paper, and sheet material, and also includes meaningful images such as characters. Not only that, but also meaningless images such as pattern images are included. Among the liquid ejection devices, the recording device includes all of various information processing devices or a printer as an output device thereof, and the present invention can be used for these devices.

[0003]

2. Description of the Related Art With respect to an ink jet recording apparatus which performs recording on a recording medium such as recording paper by discharging ink, many products have been manufactured from the viewpoint of easiness of miniaturization of the apparatus and low noise. I have.

[0004] In recent years, there has been an increasing demand for further miniaturization and high-quality color printing, especially high-quality color printing. As a configuration for satisfying such a demand, Japanese Patent Publication No. 62-48585 discloses a configuration in which a plurality of electrothermal conversion elements are provided in one nozzle, and such electrothermal conversion elements are independently provided. A gradation recording method has been proposed in which the size of ejected ink droplets is modulated by control driving to realize high-quality recording.

The present inventors have studied a gradation recording method for performing high-quality multi-gradation recording using a plurality of electrothermal transducers provided in one nozzle, and have found the following.

(1) When droplets of various volumes are ejected from within one nozzle, there is a correlation between the droplet speed and the ejection volume, and a droplet having a large ejection volume has a high speed and an ejection volume. Small droplets were found to have lower velocities. This means that the ejection speed of the droplets differs depending on the ejection volume of the droplets.When a plurality of nozzles are arranged to form a multivalued image, the landing positions on the recording medium differ. This implies that the image quality is degraded and a fine multivalued image cannot be formed.

(2) When printing is performed using a head provided with a plurality of nozzles provided with a plurality of electrothermal transducers, it is necessary to control these transducers individually in accordance with image data. , The number of the electrical contacts for applying the signal is +1. Of course, it is possible to reduce the number of contacts described above by mounting a shift register or the like, but in that case, the size of the substrate is increased, which causes an increase in cost.

(3) The biggest problem is that the speed of a droplet having a small ejection volume is extremely slow and has no momentum, and there is a problem that the ejection direction is not stable. The viscosity of the ink near the (ejection port) becomes higher due to the evaporation of water, and the orifice is clogged by the thickened substance, which causes non-ejection of the ink.

(4) In general, the ejection frequency greatly depends on the refill frequency of ink, and this refill frequency depends on the volume of the ejected droplet if the nozzle shape and the like are the same. Therefore, when dot modulation is performed, the driving frequency is determined by the ejection of the largest volume of the ejection droplet.

In summary, in a liquid ejection head having a plurality of electrothermal transducers in one nozzle, the ejection volume of liquid droplets is varied by independently driving each electrothermal transducer, thereby performing dot modulation. In this case, the ejection speed, ejection reliability, and ejection frequency of the large droplet and the small droplet are different from each other, so that there is a problem that it is difficult to improve the image quality and sufficiently increase the recording speed.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a liquid discharge head and a liquid discharge device which enable high-quality recording.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a liquid discharge head having two types of electrothermal transducers in one nozzle, and comprising two types of electrothermal transducers. Mode 1 (first
Mode) and two modes including a mode 2 (second mode) in which a bubble is generated by one of the two types of electrothermal conversion elements and the liquid is discharged. Features.

In mode 1, a relatively large droplet V
d1 is discharged, and in mode 2, a relatively small droplet Vd2 is discharged. If printing is performed in two passes in the sub-scanning direction in mode 2 and printing is performed at twice the resolution in the main scanning direction, the maximum resolution can be quadrupled.

Further, regarding the control of the electrothermal transducer,
There is no need to perform complicated control based on multi-valued image data. Mode 1 (Two types of electrothermal transducers are simultaneously turned ON / O
FF) and mode 2 (one type of electrothermal transducer is turned ON /
OFF) is only given to the head. The simplest way is to turn on the connection of one of the electrothermal conversion elements.
Switching can be performed only by turning OFF, and only one electrical contact is added. High reliability of electrical contact between the carriage and the head is achieved, and high-quality recording with very little increase in cost can be performed.

In mode 2, when the speed of the droplets is made sufficiently reliable, when the ejection volume Vd2 becomes relatively large, more ink than the ink absorbing capacity of the recording medium is used. , And the ink may bleed.

In the present invention, the above-mentioned adverse effects can be prevented by performing thinning printing with a simple mask. As described above, in the ink jet head in which a plurality of electrothermal transducers are arranged in one nozzle, the ejection volume is not modulated for each nozzle according to the density of the recorded image, and the mode is selectively used in two modes to increase the resolution. By doing so, control is easy,
An inexpensive and highly reliable liquid discharge head and liquid discharge device can be provided.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of a basic mode of an ink jet head (hereinafter, also simply referred to as a head) as a liquid discharge head according to the present invention, wherein (a) shows one of a plurality of nozzles. It is sectional drawing which shows a structure, (b)
(A) to (d) are cross-sectional views taken along the line aa in (a), and show the discharge state of the liquid according to the mode of driving two heaters as the electrothermal conversion elements.

In the head according to the present embodiment, ink is supplied from the common liquid chamber behind the nozzle 104, and rapid bubbling occurs on the discharge heaters 2a and 2b serving as heating resistors constituting a part of the electrothermal conversion element. Is ejected from the ink ejection port 40 by the pressure of.

As shown in FIG. 1C, in mode 2, bubbling occurs only on the surface of the heater 2b to discharge small droplets. As shown in FIG. 2b, foaming occurs and large droplets are ejected. The shape and area of these heaters, sheet resistance,
It is necessary to optimize the positional relationship and the like in consideration of the ejection speed and the ejection volume of the droplet.

The present inventors have made intensive studies on the above-mentioned ink jet head. As a result, even in the case of the head, the discharge speed of small droplets is often insufficient, and the discharge direction is accidentally bent or non-discharge is caused. The case is conceivable.

In order to increase the droplet speed sufficiently, there are means for reducing the area of the discharge port and increasing the electrothermal conversion element to increase the foaming pressure. If it is adopted, the magnitude of Vd1 of the relatively large liquid drop is reduced, and it becomes impossible to obtain a sufficient image density.

On the other hand, even if the latter means for enlarging the area of the electrothermal conversion element is adopted, there is a limit because it is arranged in a predetermined area. This is because when two types of electrothermal transducers are disposed in a conventional nozzle, one electrothermal transducer is disposed in one nozzle. In the case of dividing into two kinds, the efficiency is reduced and two kinds of electric heat are required compared with the case where a droplet having a large ejection volume is ejected by one kind of conversion element. It has been found that it is necessary to increase the total area of the electrothermal conversion element using the conversion element.

To solve such a problem, the inventors of the present invention have made further studies and found that the driving voltage pulse applied to the electrothermal transducer in mode 1 and the driving voltage pulse in mode 2 are different from each other. It has been found that the above problem can be solved.

That is, in mode 1, in order to drive two electrothermal transducers, it is necessary to drive in consideration of the temperature rise of the head in addition to the ejection volume and ejection speed. Since only the conversion element is driven, it is possible to drive the head almost without considering the temperature rise.

As a general method of driving an ink jet head, as shown in FIG. 2, a predetermined voltage is divided into a pre-pulse and a main pulse. In the present invention, in mode 1 and mode 2, any method such as changing the voltage, the pre-pulse, the pulse width and pulse interval of the main pulse, or using a plurality of pre-pulses may be used. By such means, the speed of the small droplets can be increased, and a highly reliable image can be obtained.

In modes 1 and 2, it is also effective to change the control temperature of the head. By increasing the control temperature of the head in mode 2 relative to mode 1, the speed of the small droplets can be increased.

It is also effective to make the foaming start energies of the electrothermal transducers different from each other.

For example, assume that the foaming start energy of the heater 2a is E1, and the foaming start energy of the heater 2b is E2 (E1
> E2), in mode 1, both heaters have E1
When the above energy is applied, bubbling occurs on the surfaces of both heaters, and Vd1 of a large droplet can be discharged. On the other hand, in mode 2, if energy of E1 or more is applied to the heater 2a and E2 or less is applied to the heater 2b, the surface temperature of the heater 2b adjacent to the heater 2a is also increased until immediately before foaming, so that ejection is performed. The discharge speed of Vd2 of small droplets can be increased.

In this embodiment, the heaters 2a, 2a
b may be simultaneously driven by the same drive pulse,
Further, a drive pulse may be individually applied.

As means for changing the foaming start energy, there is means for changing the length of the conversion element.
The most effective means is to change the thickness of the protective film. This is because foaming can be started with less energy by making the protective film thinner.

In this embodiment, as shown in FIG. 1A, a so-called edge shooter type head for discharging liquid in a direction along the upper surfaces of the heaters 2a and 2b has been described. The present invention is not limited to this, and is also applied to a so-called side shooter type head for discharging liquid in a direction facing a heater.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings, but it goes without saying that the present invention is not limited to the following embodiments. In the present embodiment, water-based ink is used as an example of the liquid used for ejection.However, the present invention is not limited to this, and any liquid ejecting recording head that can eject using the present invention can be used. It may be liquid. Before describing the embodiments of the present invention, a basic configuration and a manufacturing method of an ink jet head which the present inventors are studying will be described.

In the present invention, two types of electrothermal conversion elements are provided for one liquid flow path (hereinafter, also referred to as a nozzle).
(A), (b) are shown.

FIGS. 3A and 3B are a plan view and a sectional view taken along line AA, respectively, showing the shape of the conversion element formed on the electrothermal conversion element substrate.
It is.

The electrothermal transducer comprises a heating resistor element (hereinafter also referred to as a discharge heater) 2 for generating heat, and electrodes 3A and 3B connected to the discharge heater 2 by a thin film process used for semiconductor production. It is configured. Then, by applying a voltage between the two electrodes, a current flows through the discharge heater 2 to generate heat. The heat generated by the discharge heater 2 includes a component that radiates heat in the direction of arrow 107 shown in FIG. 3A, that is, a plane direction, and a component that radiates heat in the cross-sectional direction shown in FIG.

The discharge heater 2 has a heat storage layer 105 made of a material having low thermal conductivity and a protective film 103 formed for protecting the heater against ink, and has a resistance to a shock wave generated when the foamed ink is defoamed. It has a sandwich structure sandwiched between cavitation films 104. As the base 106, a silicon substrate is used. The thickness of each layer is determined so that the heat of the discharge heater 2 is more efficiently transmitted to the ink 108. In the case of the present invention,
The anti-cavitation film 104 is 0.1 to 1.0 μm, the protective film 103 is 0.3 to 2.0 μm, and the heat storage layer 105 is 0.1 to 1.0 μm.
A substrate having a thickness of about 5 to 5.0 μm is used, and the base 106 has a thickness of 0.5 to 1.0 mm.

Processing such as film formation, patterning, and etching of these layers can be performed by applying a general-purpose semiconductor process. Further, as an example of a means for manufacturing an ink jet recording head using a substrate, an ink supply port by injection molding, a common ink chamber, and an ink discharge port is formed by an excimer laser on a resin top plate formed with nozzles, The ink jet head can be manufactured by joining the nozzle and the discharge heater while aligning them and fixing them with a spring or the like, and then sealing the joint surface with a sealing material or the like.

Here, when the ink is water-based ink,
By setting the temperature of the surface where the anti-cavitation layer 104 and the ink 108 are in contact with each other to about 300 ° C., the ink 10 foams. The discharge heater 2 has a heat resistant temperature and a protective film 103.
Due to the difference in thermal expansion coefficient with the thermal storage layer 105 and
When the surface temperature exceeds about 700 to 800 ° C., the durability is rapidly deteriorated. Therefore, it is desirable to control the surface temperature within the above range.

FIG. 4 is a graph showing the surface temperature distribution of the heater. Aa ′ in FIG. 4 corresponds to the heater width in FIG. 3A, and the surface temperature distribution of the anti-cavitation layer 104 is indicated by TempA. ΔT1 is a foaming start temperature of about 300 ° C., and ΔT2 is a temperature at which the durability changes abruptly and varies depending on the thin film material used, but is usually about 700 to 800 ° C. ΔT1 to ΔT in TempA
The range of the two temperature regions is a region where the ink actually foams on the heater surface, and is a range indicated by bb ′.

As shown in FIG. 4, the temperature distribution at the center of the discharge heater is flat. Since the foaming / defoaming is repeated extremely stably in the flat portion, the larger this area is, the more stable printing performance can be obtained. When approaching the end of the heater, there is heat radiation in the plane direction indicated by the arrow in FIG. 3A, so that the temperature gradually decreases, and in WA, the ink cannot be foamed even though it is on the discharge heater. It becomes a foaming area. Further, the outside WB of the discharge heater is observed to have some temperature rise due to the heat radiation in the plane direction.

An embodiment of the present invention will be described based on the above basic characteristics.

FIG. 5 shows a basic mode of an element substrate in which two types of electrothermal conversion elements are formed in one nozzle. Two types of electrothermal conversion elements 2A and 2B are formed on the substrate 31, and voltage pulses are applied to the electrothermal conversion elements 2A by wirings 3A and 3B. Similarly, the electrothermal conversion element 2
A voltage pulse is applied to B by the wirings 3C and 3D.

FIG. 6 shows an arrangement of elements constituting an element substrate of an ink jet head according to an embodiment of the present invention. Nozzle walls 5 are provided on the element substrate, and two ejection heaters of a large heating resistor 2a and a small heating resistor 2b are arranged in the ejection nozzle between the nozzle walls 5. Each discharge heater is connected through a through hole 4 to a common wiring 1 below an interlayer insulating film below the discharge heater, and a voltage is applied from the common wiring. Wiring 6, 7
Connect the discharge heaters 2a and 2b to the switching transistors 11 and 10 through through holes 16, respectively.

Switching transistors 10 and 11
Is also provided below the interlayer insulating film below the heater. Further, in order to control ON / OFF of the transistors 10 and 11, signal wirings 17 and 18 are connected to the transistors 10 and 11 and the shift register latch circuits 19 and 20, respectively. Thus, the driving of the heater is controlled by turning on / off the transistor based on the data taken in by the shift register latch circuit. Ground wiring 1
2, 13, 14 and 15 are connected to the emitters of switching transistors 8, 9, 10 and 11, respectively.

FIG. 7 shows an equivalent circuit for driving the ink jet head of FIG. FIG. 7 shows the shift register latch circuits 19 and 20 in detail. The shift register 36 receives a CLK signal line 37 and a serial data line 35 and develops serial data in the shift register 36 by a clock signal. The data input to the shift register 36 is held in the latch 33 by the latch signal from the latch signal line 34. Next, the enable signal line 32 is AND
The timing signal is connected to the gate 31 and applies the data of the latch 33 to the transistor 11. Since there are two enable signal lines 32, the discharge heaters 2a and 2b can be driven simultaneously or at different timings.

Regarding the actual selection of modes 1 and 2,
By switching to this enable signal line 32, printing by only the discharge heater 2a and the discharge heater 2
It is possible to select printing in which both a and 2b are driven.

Next, the control of the ink ejection amount using the element substrate will be described with reference to FIGS. 1 (b) to 1 (d).
As shown in (b), the discharge nozzle 104 sandwiched between the nozzle walls 5 is filled with ink, and the discharge heaters 2a,
When 2b is heated, the ink is ejected from the orifice 40 by the pressure of the foam generated in the ink on each heater.
(C) shows a bubble 113 generated by heating by the discharge heater 2b.
Shows a state where the small droplet 114 (Vd2) is ejected. Next, (d) shows a state where two ejection heaters are simultaneously heated to eject a large droplet 115 (Vd1).

Conventionally, when two ejection heaters are provided in one nozzle to modulate the ejection volume, the areas of the two ejection heaters are made different, and ejection by a small ejection heater, ejection by a large ejection heater, and two ejection heaters are performed. A method of forming a quaternary multi-valued image by ejecting three types of droplets by simultaneous driving has been proposed. However, when the ejection volume is simply reduced as described above, the ejection speed of the droplets is reduced. Often slows down and lowers the reliability of the image.

Therefore, in the present invention, the small droplet Vd2
The main purpose is to make the ejection speed sufficiently high, and the ejection using only a small-area ejection heater is not used for recording, and in the mode in which the small droplet Vd2 is ejected, the large area of the two heaters is used. The discharge is performed only by the heater.

Next, FIG. 8 shows an example of a specific mode of a main part of the head having the above-described configuration. The above-described discharge heaters 2a and 2b are formed on the substrate element 1, and the element substrate 1 is adhered on a base plate 41 made of aluminum or the like in order to perform good heat radiation. A wiring board (not shown) for making contact with the printing apparatus is adhered to the rear of the base plate, and the wiring board and the element substrate are connected by wire bonding. Also, top plate 1
01 is manufactured by injection molding as described above, and the nozzle 10
4 is formed by being partitioned by a nozzle wall 5. An ink discharge port 40 is formed in front of the nozzle by excimer laser processing.

At present, a general inkjet head has a nozzle pitch of about 70.5 μm and is manufactured at a resolution of 360 dpi. Higher resolution, 720 dpi
Nozzle pitch should be about 35μ
m, but such a fine processing requires a drastic change in the manufacturing method.

However, according to the present invention, the discharge heater 2a
Only by using this method, the ejection volume can be reduced, and printing in two passes can be performed, so that printing at 720 dpi can be performed, and high resolution can be achieved while using the conventional inkjet head manufacturing technology.

FIG. 9 shows an ink jet head 5 according to the present invention.
This is an inkjet head cartridge manufactured by combining an ink tank 501 for supplying ink to the head.

FIG. 10 is a schematic perspective view showing the structure of an example of an ink jet recording apparatus as a liquid ejection apparatus of the present invention using the ink jet recording head constructed as described above. This inkjet recording apparatus IJR
A has a lead screw 2040 that rotates via driving force transmission gears 2020 and 2030 in conjunction with forward and reverse rotation of the drive motor 2010. The carriage HC on which the ink jet cartridge IJC in which the ink jet recording head and the ink tank are integrated is mounted, and the carriage shaft 2050 and the spiral groove 20 of the lead screw 2040 are provided.
41 has a pin (not shown) that engages with
As the lead screw 2040 rotates, it is reciprocated in the directions of arrows a and b.

Reference numeral 2060 denotes a paper pressing plate, which presses the paper P against the platen roller 2070 in the carriage movement direction. Reference numerals 2080 and 2090 denote photocouplers, which are levers 2 provided on the carriage HC.
It operates as a home position detecting means for confirming the existence of the motor 100 in this region and switching the rotation direction of the motor 2010 and the like. Reference numeral 2110 denotes a cap member for capping the front surface of the recording head, which is supported by a support member 2120.

Reference numeral 2130 denotes suction means for sucking the inside of the cap, and recovers the suction of the recording head through the opening in the cap. A cleaning blade 2140 for cleaning the end face of the recording head is provided on a member 2150 so as to be movable in the front-back direction.
It is supported by 60. The blade 2140 is not limited to this form, and it goes without saying that a known cleaning blade can be applied to this example. Reference numeral 2170 denotes a lever for starting suction for suction recovery, and the carriage HC
The driving force from the driving motor 2010 is controlled by a known transmission means such as clutch switching.

The capping, cleaning, and suction recovery are configured so that desired processing can be performed at the corresponding positions by the action of the lead screw 2040 when the carriage HC reaches the home position side area. If a desired operation is performed at the timing, any of the embodiments can be applied.

[Embodiment 1] In the ink jet head having the above-described structure, the number of nozzles is 128, and the dot pitch is 36.
A 0 dpi head was prototyped. The protective film and the heat storage layer of the head had a thickness of 1.0 μm, respectively, and the ejection heaters for ejecting small droplets were 20 μm in width and 115 μm in length, one of which was 26 μm in width and 112 μm in length. The distance from the end face of the substrate to the tip of the discharge heater was 60 μm. The top plate had a discharge port area of 750 μm ² , a thickness of the top of the top plate having the discharge ports of 55 μm, a nozzle shape of 43.5 μm, and a width of 60.5 μm.

Such a head was manufactured by the above-described means, and an ink-filled ink was mounted thereon to manufacture an ink jet head cartridge.

The head has a signal line which can select 360 dpi and 720 dpi, unlike the conventional ink jet head, and can switch between them by a signal from the recording apparatus. As shown in FIG. 11, ink ejection is performed in a 360 dpi print mode (first mode).
At the same time, 8 nozzles (1, 17, 33, 49, 6
5, 81, 97, and 113), and recording is performed by dividing into 16 blocks.

On the other hand, in the 720 dpi mode (second mode), 16 segments are simultaneously discharged (1, 9, 17, 25, 33, 41, 49, 57, 6).
5, 73, 81, 89, 113, 121) to prevent bending of the vertical ruled line.

That is, in the case of high resolution, if the number of simultaneous ejection segments is not increased, vertical ruled line deviation occurs or driving at a high frequency becomes impossible, and the necessary power supply capacity is extremely increased accordingly. Is 720d
Since the energy input to the ejection of one nozzle can be reduced in the Pi mode compared to the 360 dpi mode (an example in which only one ejection heater is driven), simultaneous ejection can be performed without greatly increasing the power supply of the apparatus. The number of nozzles can be increased to prevent vertical ruled line deviation. The ejection frequency was 6.0 KHz in the 360 dpi mode, and 12.0 KHz in the 720 dpi mode.

As a printing method, after printing is performed at the density of 720 dpi in the first pass in the main scanning direction, the recording medium is conveyed in the sub-scanning direction by half the pitch of the nozzles, and then moved in the main scanning direction. The high resolution of 720 dpi * 720 dpi was obtained by performing printing at a density of 720 dpi in the second pass.
A mode of dpi * 360 dpi is also used.

In the present ink jet recording apparatus, compared to a recording apparatus in which a plurality of ejection heaters are provided in one nozzle to modulate the ejection amount, the ink jet recording apparatus is limited to a low resolution mode and a high resolution mode. An increase in the power supply capacity of the device can be suppressed. Also, as for the ejection frequency, in the high resolution mode, only small droplets are ejected, and high-speed recording is possible. That is, in the ink jet head that modulates the ejection amount, large droplets that determine the ejection frequency (generally, the ejection frequency is determined by the refill speed of the ink, and the refill frequency becomes slower as the larger droplets) are ejected in accordance with the image information. And high-speed recording cannot be performed.

However, in the ink jet head according to this embodiment, a high-quality recorded image can be formed at low cost.

Example 2 A color ink jet recording head shown in FIG. 12 was prototyped. In the head according to this embodiment, 1 to 24 segments are yellow, 25 to 48 segments are magenta, 49 to 72 segments are cyan, 73
136 segments are configured to eject black ink, and each color has an interval of 8 segments.

This head uses 64 nozzles of black for printing using only black ink, and performs recording using 24 nozzles of each color for color printing. In the printing of black ink, the recording paper is conveyed at a pitch of 64 nozzles, and the color ink (Y,
In the recording of M and C), conveyance at a pitch of 24 nozzles is performed.

FIG. 13 is a schematic diagram showing a recording method according to this embodiment. As shown in FIG. 13, in the 360 dpi mode, eight segments are discharged at the same time and 720
In the dpi mode, 12 segments (1,
9, 17, 25, 33, 41, 49, 57, 65, 7
3, 81, 89).

In this embodiment, a heater for discharging small droplets having a width of 24 μm and a length of 115 μm was formed, and the other discharge heater having a width of 22 μm and a length of 116 μm was formed. Further, the top plate is similar to the previous embodiment 1, the discharge port area in the case of black 680 micrometer ^2, the color was 360 .mu.m ^2.

As the driving pulse applied to the ink jet head, a pre-pulse (t1 in FIG. 2) is set to 1.5 μsec at a driving voltage of 24 V, a pause time (t2 in FIG. 2) is set to 1.8 μsec, and a main pulse (t2 in FIG. 2) is set.
T3) was given as 3.2 μsec. Under such driving conditions, the speed of the small droplet of black ink is 6 m.
/ Sec, the discharge amount is 30 ng, and the speed of large droplets when applying voltage to both discharge heaters is 14 m / sec.
The discharge amount was 65 ng.

When an image was recorded under such driving conditions, the ejection direction was bent and printing was disturbed, although rarely. Therefore, only in the small droplet discharge mode, the pre-pulse (t1) is set to 2.0 μsec, and the pause time (t
2) was set to 3.0 μsec and the main pulse (t3) was set to 2.7 μsec, and the ejection speed was 9 m / sec.
And good printing became possible.

In the above conditions, the main pulse is set to 3.
When the time was set to 2 μsec, the speed became 12 m / sec, and it was possible to obtain a highly reliable image in which the ejection direction was not bent.

Example 3 A color ink jet head was manufactured in the same manner as in Example 2, and printing was performed with the substrate temperature controlled at 50 ° C. in the case of the small droplet discharge mode.
The temperature of the substrate was controlled by forming a temperature control heater in the substrate in the same process as the discharge heater and measuring the temperature with a diode sensor fabricated in the substrate. The substrate temperature of the inkjet head in Example 2 in which the temperature control was not performed was 30 ° C.

In this embodiment, the ejection of the small droplet is 10 m / s.
ec, and a good image could be recorded.

Example 4 A color ink jet head cartridge was produced in the same manner as in Example 2. In the present embodiment, the length of the discharge heater for small droplets is 90 μm,
The length of the other ejection heater was set to 120 μm. In this head, the pre-pulse (t1) is set to 1.5 μsec,
The pause time (t2) was 1.8 μsec, the main pulse (t3) was fixed at 3.2 μsec, and the discharge start voltage was measured while changing the drive voltage. When only the discharge heater for small droplets was driven, 17 V, and 21 V when only the other discharge heater was driven.

When a driving voltage of 23 V was applied to the two ejection heaters by the ink jet head to perform ejection, the speed of the large droplet was 15 m / sec. When the voltage was discharged at 19 V, the discharge speed of the small droplets was 12 m / sec. Under these conditions, 360 dpi mode and 72
When the image was recorded in the 0 dpi mode, good printing could be performed.

In this embodiment, a voltage pulse equal to or lower than the discharge start voltage is applied to one of the discharge heaters. As a result, even when the small droplets are ejected, the ink on the other ejection heater does not foam, but the temperature rises to near the foaming temperature, and extremely large foaming is possible by driving the small droplet ejection heater. The discharge speed of the small droplet is improved as compared with the second embodiment.

In this embodiment, two types of recording modes are set by changing the drive voltage. However, it is also possible to change the drive pulse to drive.

Example 5 A color ink jet head cartridge was produced in the same manner as in Example 2. In the present embodiment, the thickness of the protective film of the small droplet discharge heater is set to 0.
5 μm, and the thickness of the protective film of the other discharge heater is set to 1.0 μm.
μm. As for the protective film, once the film thickness is 1.0 μm
After the silicon nitride film was formed by sputtering, only the upper portion of the small droplet discharge heater was etched with hydrogen fluoride gas to reduce the thickness of the protective film.

When a drive voltage was applied only to the small droplet discharge heater in the same manner as in Example 4, the discharge start voltage was 16.
It was 5V. 20.5 V for the other discharge heater
Met. When a driving voltage of 23 V was applied to this inkjet head, the ejection speed of large droplets was 14 m / sec.
c, the discharge volume was 68 ng. On the other hand, when a driving voltage of 19 V was applied when discharging small droplets, the discharge speed was 11 m / sec and the discharge volume was 40 ng.

In the present embodiment, since the ejection amount of the small droplet is relatively large, only 12. dpi at 720 dpi in the main scanning direction.
Image formation was performed at 5 kHz. In addition, 720 dpi * 72
In the print mode of 0 dpi, when the recording was performed by thinning out the ejection at a uniform rate of 30%, good printing was possible.

[0083]

As described above, according to the present invention,
Since two discharge heaters are formed in one nozzle to have two modes of a low resolution mode and a high resolution mode,
It has the following excellent effects.

1: An inexpensive recording apparatus capable of obtaining a high-quality recorded image can be provided.

2: In the low-resolution mode, by adopting the same specifications such as the resolution as in the past, it is possible to increase the resolution while maintaining the compatibility of the head, so that high-quality heads can be marketed without increasing the types of heads. Can be provided.

3: Only the number of terminals for applying one signal for switching between the two modes is increased, so that the carriage and the like can reliably contact the head and the recording apparatus with the conventional design.

4: Since droplets of various discharge amounts are not discharged for each nozzle, high-speed recording can be performed. 5: At the time of discharging a small droplet, since it is driven by another driving voltage pulse, the discharging speed of the small droplet is increased, and highly reliable recording is possible.

6: By changing the bubbling start energy of the two discharge heaters, the temperature of the surface of the other discharge heater also rises when discharging a small droplet, and the discharge speed of the small droplet increases. High recording is possible.

7: By changing the thickness of the protective film,
The foaming start temperature of the discharge heater can be changed, and there is no need to reduce the area of the discharge heater, and a highly reliable ink jet head that does not cause discharge deterioration even when kogation or the like occurs can be provided.

[Brief description of the drawings]

FIG. 1A is a cross-sectional view illustrating a main part of an inkjet head as a liquid ejection head according to the present invention, and FIGS.
(D) is sectional drawing which follows the aa line of (a).

FIG. 2 is a graph showing the shape of a voltage pulse applied to a discharge heater.

FIGS. 3A and 3B are a plan view and a sectional view taken along line AA, respectively, showing the shape of a conversion element formed on an electrothermal conversion element substrate.

FIG. 4 is a graph for explaining a foaming region of the electrothermal conversion element.

FIG. 5 is a plan view showing a configuration in which two discharge heaters are arranged in one flow path.

FIG. 6 is a plan view showing an arrangement of elements on a substrate constituting a base of the ink jet recording head according to one embodiment of the present invention.

FIG. 7 is a diagram showing an equivalent circuit of FIG. 6;

FIG. 8 is an exploded perspective view showing a main part of an ink jet head as a liquid ejection head of the present invention.

FIG. 9 is a schematic perspective view showing a basic mode of an ink jet head cartridge including the liquid discharge head of the present invention.

FIG. 10 is a schematic perspective view showing a basic mode of a recording apparatus which carries out recording by mounting an ink jet head cartridge of the present invention.

FIG. 11 is a schematic diagram showing the ejection timing of the inkjet head of the present invention.

FIG. 12 is a diagram illustrating a nozzle configuration of an inkjet color head to which the present invention is applied.

FIG. 13 is a diagram showing ejection timings at which printing is performed using the head of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Common wiring 2A, 2B, 2a, 2b Electrothermal conversion element 3A, 3B, 6, 7 Wiring electrode 8, 9, 10, 11 Switching transistor 12, 14, 15 Ground wiring 17, 18 Signal wiring 19, 20 Shift register latch Circuit 21 Ground vertical wiring 22 Common vertical wiring 23 Substrate 24 Contact 25 Cell 31 AND gate 32 Enable signal 33 Latch 34 Latch signal line 35 Serial data line 36 Shift register 37 CLK signal line 38 Decoder circuit 39 Decoder signal line 40 Orifice 41 Substrate 42 , 43, 45, 46 Heater 44 Ink preheater 51 Interlayer insulating film 53 Silicon layer 104 Discharge nozzle 109 Nozzle wall 112 Large foam 113 Small foam 120, 121 Foam

Claims (12)

[Claims] 1. A liquid flow path having a discharge port for discharging a liquid, and two kinds of liquid flow paths provided corresponding to the one liquid flow path for generating heat energy for discharging the liquid. A first mode in which the two types of electrothermal conversion elements are independently driven by each type to discharge the liquid at a volume of Vd1, and a volume of Vd2 smaller than the Vd1. And a second mode for discharging the liquid with higher definition than the first mode. In the case where the liquid is discharged in the first mode, the two types of electricity are discharged. When simultaneously applying voltage drive pulses of the same condition to the heat conversion element and ejecting the liquid in the second mode, to one of the two types of electrothermal conversion elements, Driving condition in the first mode Furthermore the liquid discharge head characterized in that it comprises a driving pulse applying means for applying a driving pulse at the different conditions. 2. The method according to claim 2, wherein when the liquid is ejected in the second mode, the drive pulse applying unit applies a drive pulse equal to or less than an ejection drive voltage to the other electrothermal transducer. Item 2. The liquid discharge head according to Item 1. 3. A liquid flow path having a discharge port for discharging a liquid, and two kinds of liquid flow paths provided corresponding to the one liquid flow path for generating thermal energy for discharging the liquid. A first mode in which the two types of electrothermal conversion elements are independently driven by each type to discharge the liquid at a volume of Vd1, and a volume of Vd2 smaller than the Vd1. A liquid ejection head having a second mode for ejecting the liquid with higher definition than the first mode, wherein when the liquid is ejected in the second mode, the first mode is used. The liquid discharge head according to claim 1, further comprising a unit configured to control a temperature higher than a control temperature of the liquid discharge head when discharging the liquid. 4. The liquid ejection head according to claim 3, wherein said temperature control means includes a heating resistor formed in the same step as a heating resistor constituting said electrothermal transducer for discharging liquid. . 5. A liquid flow path having a discharge port for discharging a liquid, and two types of liquid flow paths provided to correspond to the one liquid flow path for generating thermal energy for discharging the liquid. A first mode in which the two types of electrothermal conversion elements are independently driven by each type to discharge the liquid at a volume of Vd1, and a volume of Vd2 smaller than the Vd1. A second mode for ejecting the liquid with higher definition than the first mode, wherein the one electric heat used for ejecting the liquid in the second mode. A liquid discharge head, wherein a liquid foaming start temperature of the conversion element is set lower than a liquid foaming start temperature of the other electrothermal conversion element. 6. The liquid discharge head according to claim 5, wherein the two types of electrothermal transducers are arranged in the liquid flow path along a direction intersecting the length direction. 7. The two types of electrothermal transducers have different dimensions along the length direction of the liquid flow path, and the two types of electrothermal transducers start foaming due to the difference in these dimensions. The voltage is different from each other.
Or the liquid discharge head according to 6. 8. On the two types of electrothermal transducers,
6. The liquid ejection head according to claim 5, wherein protective films having different thicknesses are provided, respectively, and the foaming start voltages of the two types of electrothermal transducers are different due to the difference in the film thicknesses. 9. The liquid discharge head according to claim 1, wherein the liquid is ink. 10. The discharge port according to claim 1, wherein the discharge port is arranged in a direction along an upper surface of the electrothermal transducer.
Item 10. The liquid discharge head according to any one of Items 9 to 9. 11. The discharge port according to claim 1, wherein the discharge port is arranged in a direction facing the electrothermal transducer.
10. The liquid discharge head according to any one of items 5, 8, and 9. 12. A liquid flow path having a discharge port for discharging a liquid, and two kinds of liquid flow paths provided to correspond to the one liquid flow path and for generating heat energy for discharging the liquid. A first mode in which the two types of electrothermal conversion elements are independently driven by using a liquid discharge head including an electrothermal conversion element, and the liquid is discharged in a volume of Vd1; A liquid ejection apparatus which ejects the liquid in a second mode in which the liquid is ejected with a smaller volume of Vd2 with higher definition than in the first mode, wherein the liquid is ejected in the first mode. Wherein at least one condition selected from a liquid discharge condition group consisting of a drive pulse, a temperature control, and a drive voltage is made different between the case and the case of discharging the liquid in the second mode. .