JPH1016225A - Ink jet recording head and ink jet recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the discharge of ink whose emission amount is especially variable on optimal emission conditions by configuring an ink jet recording head with two electrothermal conversion elements which are switched according to various sets of information as an ink jet recording head which emits the same amount of liquid droplet if the electrothermal conversion elements are independently driven from each other. SOLUTION: An element substrate 23 consisting of front heaters 2 and rear heaters 4 as electrothermal conversion elements is arranged on a support 41 formed of metal such as aluminum. Orifices 40 as ink emission ports and nozzle grooves, each of which is formed of a nozzle wall 5 and communicates with the orifice 40, are provided on a top plate 101. In addition, nozzles 104 and an ink chamber 105 are formed by junctioning the element substrate 23 with the top plate 101, and if ink is supplied to the nozzles 104 from the ink chamber 105, the heaters 3, 4 generate heat due to a signal current, and the ink in the nozzles 104 is heated to generate a bubble. This bubble generation results in the discharge of the ink from the nozzles 104 to a recording medium through the orifices 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording head for discharging a recording liquid toward a recording medium by inputting an electric signal, and an ink jet recording head.
The present invention relates to an ink jet recording apparatus that records characters, image images, and the like on a recording medium.

[0002]

2. Description of the Related Art Ink jet recording apparatuses are mostly known as printing apparatuses in printers, facsimile machines, word processors, copiers, and the like. In particular, thermal energy is used as energy used for ink ejection.
An ink jet recording apparatus of a type that discharges ink by bubbles generated by this has been spreading recently.

Further, as another application of the ink jet recording apparatus of this type, it has recently been used in an ink jet textile printing apparatus for printing a predetermined pattern, picture, or composite image on a cloth.

An ink-jet head used in the above-described ink-jet recording apparatus uses an electro-thermal conversion element (hereinafter, also referred to as a "heater") to generate thermal energy. , A configuration having one heater is adopted. On the other hand, an apparatus provided with a plurality of heaters corresponding to one discharge port has been conventionally known from the following viewpoints.

In other words, first, a plurality of heaters are driven alternately or one by one in order to extend the life of the ink jet head. Second, a plurality of heaters are used for the purpose of increasing the range in which the ink ejection amount is changed. In this case, the ejection amount is selected by selecting a heater to be driven (that is, a heater that generates heat) and the number thereof. Is changing.

In the latter case, a more specific configuration is as follows:
A plurality of heaters are arranged in the ink discharge direction in the liquid flow path communicating with the discharge port of the ink jet head, and the distance between the discharge port and the center of the driven heater is varied by selecting the heater to be driven or the number thereof. There is known a device that changes the discharge amount by this.

[0007] As another configuration, a plurality of heaters having different surface areas are arranged in the liquid flow path.
It is known to change the amount of ink discharged by changing the number of heaters to be driven or the number thereof.

[0008]

However, there are several problems in realizing an ink jet recording apparatus capable of changing the ejection amount.

One problem is that when a small amount of ink is ejected, the ink is foamed by a heater having a small ejection power, that is, a heater having a small heater area, so that not only the ejection amount but also the ejection speed is reduced. It is particularly important that a problem arises with so-called preliminary ejection performed as part of the ejection recovery process.

That is, the preliminary ejection generally involves ejecting ink which is not involved in recording from the ink jet head at a predetermined place in the apparatus, thereby removing the thickened ink and the like in the ink jet head and causing the ink ejection state. Can be kept good. Such preliminary discharge
Usually, this is performed at regular time intervals immediately after the power of the apparatus is turned on or during printing.

However, when printing is performed with a small ejection amount set, it is necessary to shorten the interval between preliminary ejections. That is, if the interval is too long, the power of the small ejected ink droplet is small, and depending on the degree of thickening of the ink due to the evaporation of the water at the ejection port, there is a possibility that the thickened ink may not be stably ejected. is there. In particular, it is necessary to shorten the interval between preliminary ejections performed at regular time intervals during printing, and the printing throughput also decreases.

Another problem is that when printing is performed with a small ejection amount set, the resolution increases, the image data amount increases, and the number of printing dots increases. I can't do it fast.

[0013] The above-mentioned problems are greatly affected by the type of ink.

In view of the above-mentioned problems of the prior art, an object of the present invention is to use an ink jet recording head having a plurality of electrothermal transducers in one nozzle with a relatively simple configuration, It is an object of the present invention to provide an ink jet recording head and an ink jet recording apparatus capable of performing a discharge (recording) in which a discharge amount is particularly variable under a discharge condition most suitable for a purpose or a use condition.

[0015]

In order to achieve the above object, the present invention has a plurality of electrothermal transducers arranged in an ink flow passage communicating with an ink discharge port, and two of the electrothermal transducers are provided. The heat conversion elements were arranged at different distances from the discharge ports to the electrothermal conversion elements, and the discharge amounts of droplets when the two electrothermal conversion elements were independently driven were made substantially the same. An ink jet recording head, wherein a driven electrothermal transducer is switched according to various information.

The various information is the temperature of the head body,
In particular, the present invention is characterized in that when the temperature of the head main body is low temperature or low humidity, the electrothermal conversion element on the side close to the discharge port is driven.

The various information is a print mode,
The printing mode includes a large discharge amount mode for driving both of the two electrothermal conversion elements, and a small discharge amount mode for driving any one of the electrothermal conversion elements. In the mode, when driving the electrothermal transducer on the side closer to the ejection port, the mode is the ejection reliability emphasis mode or the image quality precision emphasis mode. When driving the electrothermal transducer on the side farther from the ejection port, the high-speed print mode is used. It is characterized by being.

Further, the various types of information are the types of recording liquids. In particular, in the present invention, when the type of the recording liquids is ink that dries more easily than ordinary ink, the electric heat on the side close to the discharge port is used. The conversion element is driven.

Further, the various information is the type of the printing apparatus main body. In particular, according to the present invention, when the type of the printing apparatus has a driving unit smaller than the size of the driving unit for normal head scanning. Is characterized in that the electrothermal conversion element on the side closer to the discharge port is driven.

The ink jet recording head as described above is characterized in that the driving frequency of the electrothermal transducer, the pre-ejection conditions, the PWM table, the ejection timing, etc. are changed according to the switching of the electrothermal transducer.

Further, the present invention also provides an ink jet recording apparatus which removably mounts the ink jet recording head described above, reciprocates the ink, and discharges ink from the ink jet recording head according to a desired drive signal to perform recording on a recording medium. Belong.

The invention as described above has a plurality of electrothermal transducers disposed in an ink flow path communicating with the ink ejection port, and two of the electrothermal transducers are electrically connected to the respective ejection ports from the ejection port. An ink jet recording head in which the distances to the heat conversion elements are different from each other, and the discharge amounts of droplets when the two electro-thermal conversion elements are driven independently are substantially the same. By switching the electrothermal conversion elements to be performed, the discharge speed increases as the position of the electrothermal conversion elements approaches the discharge port, and the refill frequency is opposite to the discharge speed, and the position of the electrothermal conversion element changes to the discharge port. By making full use of the ejection characteristics that become smaller as the distance becomes closer, it becomes possible to perform ejection under ejection conditions that are optimal for various types of information.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been made from a novel viewpoint as a result of studying the practical use of a recording apparatus in the head configuration described below.

First, the structure of an ink jet recording head according to the present invention will be described with reference to FIGS.

FIG. 1 is a schematic perspective view of an ink jet recording head. This recording head is called an edge shooter type, and the arrangement density of the nozzles is 360 DPI.
It has become.

As shown in FIG. 1, an element substrate 23 provided with a plurality of heaters as electrothermal conversion elements is provided on a support 41 made of metal such as aluminum. The top plate 101 is provided with an orifice 40 serving as a discharge port for discharging ink, and a nozzle groove formed by the nozzle wall 5 and communicating with the orifice 40. FIG.
The nozzle 104 and the ink chamber 105 are formed by joining the element substrate 23 and the top plate 101 as shown in FIG.

FIG. 2 is a schematic diagram showing the arrangement of heaters on the element substrate 23 shown in FIG. In one nozzle between the nozzle walls 5, two heaters, a front heater 3 and a rear heater 4, respectively have a distance O from the orifice 40 to the heater.
H are arranged differently and are partially horizontal (in a direction perpendicular to the ejection direction on the substrate surface). Each of the heaters 3 and 4 is connected through a through hole 2 to a common wiring 1 below an interlayer insulating film below the heater, and a voltage is applied from the common wiring 1. The wires 6 and 7 are connected to the front heater 3 and the rear heater 4, respectively.

That is, from the ink chamber 105 to the nozzle 10
Ink is supplied to the nozzle 4, and a heater provided in the nozzle 104 generates heat by a signal current, heats and foams the ink in the nozzle 104, and discharges the ink in the nozzle 104 from the orifice 40 toward the recording medium by the foaming. It has a configuration.

Next, the ejection characteristics of the above-described ink jet recording head will be described.

The distance O between the heater and the orifice shown in FIG.
H is a large factor that affects the ejection characteristics. When the distance OH is set as a parameter within a range set to be somewhat short, the discharge amount Vd of the droplet (pl; picoliter) and the discharge speed v
(M / s) and the refill frequency fr (KHz) have been found to have characteristics as described below.

Here, it is assumed that two heaters 3 and 4 having substantially the same size and the same length are arranged in the nozzle. When the front heater and the rear heater are independently driven, the ejection amount V of the small droplet (small dot)
d is set to be substantially the same at about 20 pl. By driving the two heaters at the same time, it is assumed that a discharge amount of a large droplet (large dot) of about 40 pl, which is about twice as large, is discharged.

When the front and rear heater sizes are the same, it is better to drive the rear heater 4 farther from the discharge port (having a longer OH), as shown in FIG.
r is much better. In other words, the meniscus return time is shortened, so that the refill frequency fr is increased. Therefore, when the rear heater 4 is driven alone, high-speed printing is possible. However, as shown in FIG. 4, the ejection speed v becomes slow. Conversely, when the front heater 3 closer to the discharge port (shorter OH) is driven alone, the discharge speed is significantly improved as shown in FIG. 4, but on the other hand, as shown in FIG. , The refill frequency becomes lower.
As described above, it has been found that the ejection speed and the refill frequency are in an opposite relationship. At this time, as shown in FIG. 3, the discharge amount Vd is substantially constant with respect to the OH distance, so that any OH distance may be selected as long as the discharge amount Vd is within a range where the discharge amount Vd is substantially constant. I do not care.

Depending on the setting method, for example, FIG.
By setting the OH distances such as the middle points B2 and A2, the heater size of the rear heater 4 is made slightly larger than the heater size of the front heater 3 (the same length and slightly wider width). Therefore, it is possible to make the discharge amounts when the respective heaters are driven independently almost the same, and conversely, by setting the OH distance like the points B1 and A1 in FIG. Alternatively, the heater size of the front heater 3 may be larger than that of the rear heater 4. Even in such a case, it has been basically found that the above-described ejection characteristics do not change much.

By the way, at the discharge port, the ink thickens as the water evaporates. Therefore, a nozzle that does not perform discharge for a while may not be able to perform stable discharge at the next discharge, and the discharge direction may be curved or non-discharge may occur. When the ink temperature is low, the viscosity is further increased because of the temperature dependence of the viscosity of the ink itself.

Therefore, in the ink jet recording apparatus, stable ejection is maintained by performing preliminary ejection to a non-printing portion at predetermined time intervals during printing. For example, in a low-temperature / low-humidity environment, the interval between preliminary ejections is reduced. Must be shorter.
In addition, since the preliminary ejection is performed in a predetermined non-printing portion, it takes time. Therefore, even if the ejection frequency is increased, the actual printing time may be prolonged. In addition, if it is performed frequently, the ink consumption due to the preliminary ejection does not become ridiculous.

Here, along with the above-described ejection characteristics, the O 2 in the case where the head main body is in a normal temperature environment and in the case where the head body is in a low temperature / low humidity.
FIG. 6 shows the relationship between the H distance and the preliminary ejection interval and the stable ejection area immediately after the suspension of the ejection of small dots. As shown in the figure,
It can be seen that if the OH distance is short, the preliminary ejection interval t can be dramatically increased. As described above, the preliminary ejection interval and the ink refill frequency have an opposite relationship.

However, as shown in FIG. 6, it can be understood that even if the OH distance is relatively long in a normal temperature environment, the preliminary ejection interval does not become so short as to be problematic.

As described above, the head of the present invention has two heaters having different OH distances in one nozzle, and small droplets (small dots) having substantially the same discharge amount in each drive.
Can be discharged, but it has been found that the discharge characteristics are different depending on the driven heater.

Therefore, various embodiments utilizing the above-described ejection characteristics of the head to the maximum will be described below.

(First Embodiment) FIG. 7 is a block diagram for explaining a first embodiment of the ink jet recording head of the present invention.

This embodiment is an example in which the heater to be driven is switched according to the temperature environment information of the main body. This head has an ejection amount mode, a print mode,
Equipped with a detection means (temperature sensor) for the temperature inside the body, according to the selected desired mode and at the same time, according to the temperature inside the main body,
The heater to be driven is switched, and ejection is performed under conditions suitable for the switched heater.

First, the discharge amount mode will be described. The discharge amount mode basically has two modes, a small discharge amount mode and a large discharge amount mode. The main heater to be driven is switched according to these discharge amount modes. The small discharge amount mode includes a first small discharge amount mode in which only the rear heater is driven, and a second small discharge amount mode in which only the front heater is driven and discharges the same amount as in the first small discharge amount mode. Discharge mode. The large discharge amount mode is a mode in which both the front heater and the rear heater are driven.

Next, the print mode will be described. The printing modes include, for example, a basic printing mode of 360 dpi, a high-density printing mode of 720 dpi, a smoothing mode for smoothing unevenness of the outline of printing, and a multi-value recording mode.

In the basic density print mode, 360 dpi printing is performed in the large discharge rate mode using all nozzles.
In the high-density printing mode, basically, all nozzles are used in the small ejection amount mode, and interlaced printing in the sub-scanning direction, that is, printing that fills the interval between print dots in the recording medium feed direction orthogonal to the head scanning direction. As a result, 720 ×
Print at 720 dpi. In the smoothing mode, the contour of the print in the 360 dpi basic density print mode is smoothed by using a discharge amount equal to or less than the discharge amount in the basic density print mode (here, a small discharge amount mode). . In the multi-value recording mode, large dots in the large ejection amount mode and small dots in the small ejection amount mode are switched for each pixel. In this case, by using paper having a small ink bleeding rate, three-valued (no dot, large dot, small dot) gradation expression can be effectively achieved for one pixel.

Next, a case where a desired mode is selected will be specifically described.

(1). When the basic density printing mode is selected, both of the two heaters are driven in the large discharge amount mode (see FIG. 8A), and printing is performed at a driving frequency of 6 KHz. The ejection amount at this time was 70 pl for black ink and 4 for color ink.
It was set to 0 pl.

(2). When the high-density printing mode is selected, the printing is performed in one of the first small ejection amount mode and the second small ejection amount mode.

In the case of the first small discharge amount mode, high-speed printing can be performed at a driving frequency of 12 KHz which is twice the basic density printing by using the rear heater. This operation mode is called “high-speed printing mode”. The ejection amount at this time was set to 35 pl for black ink and 20 pl for color ink. The scanning speed of the head is the same as in the basic density print mode of 360 dpi.

In the case of the second small discharge amount mode, the front heater is driven and 8 KH which is slightly lower than in the high-speed printing mode is set.
While printing is performed at a drive frequency of z, printing can be performed with a higher ejection speed, that is, a higher ejection power than in the high-speed printing mode. This operation mode is referred to as “ejection reliability emphasis mode”. The ejection amount at this time is the same as the ejection amount in the first small ejection amount mode.
1, the color ink was set to 20 pl. The scanning speed of the head was set to 2/3 of the high-speed printing mode.

The switching between the "high-speed printing mode" and the "ejection reliability emphasis mode" in the above-described high-density printing mode is performed according to the temperature environment of the head monitored by the detecting means (temperature sensor) (FIG. 8B). )reference).

That is, when the head is in the normal environment, printing is performed in the "high-speed printing mode". However, in this high-speed print mode, the rear heater is driven,
When the head is in a low-temperature / low-humidity environment, the interval between preliminary ejections needs to be considerably shortened as can be seen from the graph shown in FIG. Further, the preliminary ejection is an operation that takes time to perform in a predetermined non-printing section. Therefore, even if the ejection drive frequency is increased in the high-speed printing mode, the pre-ejection interval must be set to be considerably short, so that the actual printing time becomes long. In addition, if the preliminary ejection is frequently performed, the ink consumption is large.

Therefore, in the present embodiment, when a low temperature or low humidity environment of the head is detected by a temperature sensor or the like in the head main body such as a thermistor, it becomes possible to prevent the ink from becoming difficult to be ejected due to the viscosity increase of the ink at the ejection port. Therefore, the mode is switched to the “ejection reliability emphasis mode”, and printing is performed by the front heater having high ejection power.

According to the ejection reliability emphasis mode, the ejection driving frequency of the head is set to 8K which is slightly lower than that in the high-speed printing mode.
As can be seen from the graph of FIG. 6 in terms of Hz, the interval of the preliminary ejection can be increased, so that the time required for the preliminary ejection can be shortened, and as a result, the printing speed has been substantially increased. In addition, the consumption of ink has been reduced.

(3). When the smoothing mode is selected, the nozzle that discharges small dots equal to or smaller than the discharge amount in the basic density printing mode with respect to the outline of the dot printing in the basic density printing mode, as in the high density printing mode described above, High-speed print mode in which only the rear heater is driven when the inside is in a normal temperature environment (first small discharge amount mode)
When the inside of the head body is in a low-temperature / low-humidity environment, the mode is switched to the ejection reliability emphasis mode (second small ejection amount mode) in which only the front heater is driven.

(4). Even if you select multi-value recording mode,
For nozzles that eject small dots, high-speed printing mode that drives only the rear heater when the head body is in a normal temperature environment, and discharge reliability that drives only the front heater when the head body is in a low-temperature / low-humidity environment The mode is switched to the sex-oriented mode.

When the ejection amount mode is switched by one nozzle as described above, ink droplets having different ejection amounts are ejected from the same nozzle, and the ejection speed changes between the large ejection amount mode and the small ejection amount mode. I do. Therefore, when the above-mentioned smoothing mode or multi-value recording mode is selected,
Since the large and small dots are ejected while the head is scanning in the forward scan, the landing accuracy may be inferior due to the difference in the ejection speed of the large and small dots. Therefore, in the present embodiment, the ejection timing of ink droplets is changed in accordance with the ejection amount mode, so that the center positions of landing of large and small dots are aligned.

Specifically, since the larger the ejection amount is, the higher the ejection speed is, the ejection timing of the large dot is delayed. However, when the front heater is driven even for a small dot (in the case of the second small ejection amount mode), the ejection speed of the small dot can be increased, and the ejection speed difference between the small dot and the large dot can be reduced. May be good.
As described above, even in a smoothing mode or a multi-value recording mode in which large and small dots are ejected in a mixed manner while the head is scanning in the forward direction, by changing the ejection timing according to the switching of the heater, a highly accurate image can be obtained. can get.

When the smoothing mode or the multi-value recording mode is selected, even if the head configuration is such that the large dot and the small dot cannot be switched in a short time during the forward scanning of the head, even in the forward scanning direction of printing. By ejecting large dots and small dots in the backward scanning direction, a highly accurate image can be obtained.

Further, so-called pre-heat PWM control using double pulses is usually performed for the heater to stabilize the discharge amount. However, if the position of the heater in the nozzle is different, the characteristic of the change in the discharge amount due to the pre-heat condition is also different. . Therefore, in the present embodiment, by changing the PWM table according to the position of the heater to be driven, the difference in the discharge characteristics in the double pulse depending on the position of the heater is corrected and stabilized.

According to the above-described embodiment, when ink droplets smaller than the ejection amount of the basic density printing are used, the problem caused by the viscosity increase of the ink at the time of the preliminary ejection due to the temperature environment of the head main body is solved by the temperature. Depending on the environment, small dots are ejected by the front heater with high ejection power (ejection speed),
This can be solved by selecting whether to discharge small dots by the rear heater having a high discharge drive frequency.

A recording device such as a printer to which this embodiment is applied can be adapted to the environment and season of the region where the recording device is destined, without having to determine the specifications of the head before shipping according to the environment of each country in the world. And good images can be provided.
In this case, the print mode may be switched on the panel of the apparatus main body or on the screen of a personal computer or the like according to the environment or the season.

Here, an example has been described in which the position of the driven heater is switched in accordance with the temperature environment of the head main body. When the front heater that can perform high power (ejection speed) ejection can be selected, and the landing accuracy and ejection reliability are somewhat inferior, but high printing speed is important, the rear heater with high ejection drive frequency can be selected. In order to provide a new ink jet recording head, the position of the heater to be driven may be switched according to the purpose of use of the head irrespective of the head temperature information.

(Second Embodiment) FIG. 9 is a block diagram for explaining an ink jet recording head according to a second embodiment of the present invention.

This embodiment is an example in which the heater to be driven is switched according to the type information of the ink used for the head when printing with small dots. That is, there is a case where an ink that is easier to dry than an ordinary ink is provided as an option. When such ink is used, as can be seen from the graph shown in FIG. 4, the discharge power (discharge speed) is small when the small discharge amount is set by the rear heater. It is necessary to make the interval of the preliminary ejection shorter than in the case of the above ink. Therefore, in the present embodiment, when the special ink is used, the driving is switched to the driving of the front heater having a high ejection power (ejection speed).

In this case, for example, a notch or the like is provided on the head side or the tank side using the special ink, and an ID (identifying means) for using either the front side heater or the rear side heater is provided. The detection may be switched to the heater to be driven, and the driving frequency, the preliminary ejection condition, and the PWM table may be switched according to the switched heater. Further, when ink is selected on a panel of a recording apparatus main body or a screen of a personal computer or the like, a heater to be driven and a drive frequency or the like according to the switched heater may be switched.

(Third Embodiment) FIG. 10 is a block diagram for explaining a third embodiment of the ink jet recording head of the present invention.

In this embodiment, when printing with small dots, depending on the type of recording apparatus main body in which the head is used,
This is an example of switching the heater to be driven. As a form of a product, there is a case where a small body and a low cost are required even if the printing speed is slightly slow. That is, although the head is the same, the type of the recording apparatus main body may be changed.

For example, if the moving speed of the carriage on which the head is mounted is reduced to make the carriage smaller, the torque of the motor for driving the carriage can be reduced, so that the cost of the motor is reduced and the power supply capacity is reduced. Power supply can be made cheaper. In this case, it is set so that only the front heater having a low ejection driving frequency is used.

As described above, if the printing speed is somewhat slow depending on the type of the apparatus main body, but the product cost is important, the front heater having a low ejection driving frequency is selected, and the landing accuracy and the ejection reliability are somewhat low but high. When printing speed is important, a rear heater having a high ejection driving frequency may be selected.

(Other Embodiments) In this embodiment, these electrothermal transducers are efficiently driven by a head in which a plurality of electrothermal transducers are arranged in one nozzle, and the size of the element substrate is reduced. The circuit of the element substrate for achieving the above will be described. It should be noted that the term "on the substrate" used in this embodiment is used as a word including the inside near the surface of the substrate.

FIG. 11 shows an arrangement of elements constituting an element substrate according to another embodiment of the ink jet recording head of the present invention. A nozzle wall 5 is provided on the element substrate,
In one discharge nozzle between the nozzle walls 5, two discharge heaters of an electrothermal converting element (hereinafter, referred to as a "discharge heater") 2a and a discharge heater 2b are provided under the conditions described in the first embodiment. It is arranged in. Each discharge heater is connected via 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 1. The wirings 6 and 7 connect the discharge heaters 2 a and 2 b to the switching transistors 11 and 10 through the through holes 16, respectively.

Switching transistors 10 and 11
Are also arranged 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 shift register / latch circuits 19 and 20, respectively. As a result, the driving of the heater is limited by turning on / off the transistor based on the data fetched by the shift register / latch circuit. The ground lines 12, 13, 14 and 15 are connected to the emitters of the switching transistors 8, 9, 10 and 11, respectively. FIG. 11 shows a configuration for two nozzles,
FIG. 12 shows the arrangement of the entire substrate. In FIG. 12, the element substrate 1 is configured by a continuous arrangement of cells 25 having a single configuration. The common wiring 42 is connected to the contact 24 by the common vertical wiring 22 and receives supply from an external power supply. Ground wiring 12,
13, 14, and 15 are connected to the contact 24 by the vertical ground wiring 21. FIGS. 13 and 14 show equivalent circuits of FIGS. 11 and 12, respectively. FIG. 13 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 32 is connected to the AND gate 31 and inputs a timing signal for applying the data of the latch 33 to the transistor 11. Since there are two enable signals 32, the ejection heaters 2a and 2b can be driven simultaneously or at different timings. FIG. 14 is an equivalent circuit of the entire configuration of the substrate in which the cells of FIG. 13 are arranged continuously. Here, there are a decoder circuit 38 and a decoder signal line 39, which are used for various driving timings, whereby it is possible to drive with many contacts with a small number of contacts without having a plurality of enable signals 32. it can. FIG. 15 shows these basic timing charts.

FIG. 16 shows an ink jet head cartridge IJC in which an ink jet head 500 according to the present invention and an ink container 501 holding ink to be supplied to the ink jet head 500 are detachably connected.
FIG.

The ink may be injected into the ink container constituting the ink jet head cartridge as follows.

By connecting an ink supply pipe or the like to the ink container, an ink introduction path for introducing ink may be formed, and the ink may be injected into the ink container via the ink introduction path. As the ink supply port on the ink container side, a supply port on the ink jet head side, an air communication port, a hole formed in a wall surface of the ink container, or the like may be used.

FIG. 17 is a schematic view showing an example of an ink jet recording apparatus equipped with the ink jet recording head constructed as described above. This ink jet recording apparatus IJRA has a lead screw 2040 that rotates via driving force transmission gears 2020 and 2030 in conjunction with forward and reverse rotation of a driving motor 2010. A carriage H on which an inkjet head cartridge IJC in which an inkjet recording head and an ink tank are integrated is mounted.
C is the carriage shaft 2050 and the lead screw 2
040, and has a pin (not shown) that engages with the wire groove 2041 of the lead screw 2040, and reciprocates in the directions of arrows a and b with the rotation of the lead screw 2040. Reference numeral 2060 denotes a paper pressing plate, which presses the paper P against the platen roller 2070 in the carriage movement direction. 2080 and 2090
Is a photocoupler, which operates as a home position detecting means for confirming the presence of the lever 2100 provided on the carriage HC in this area and switching the rotation direction of the motor 2010. 2110, a cap member for capping the front surface of the recording head;
Supported by Reference numeral 2130 denotes suction means for sucking the inside of the cap, and performs suction recovery 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-rear direction, and these are supported by a main body support plate 2160. The blade 2140 is not limited to this form, and it goes without saying that a well-known cleaning blade can be applied to this embodiment. Also, 217
Reference numeral 0 denotes a lever for starting suction for recovery of suction, which is adapted to move with the movement of the cam 2180 engaged with the carriage HC.
The driving force from 0 is controlled by known transmission means such as clutch switching.

The capping, cleaning, and suction recovery are configured so that desired operations 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. Each of the configurations described above is an excellent invention when viewed alone or in combination, and shows preferred configuration examples for the present invention.

The relationship between the arrangement of the front heater and the rear heater and the discharge characteristics described in the first to third embodiments will be described in more detail.

FIG. 18 is a diagram showing both the relationship between the discharge amount Vd of the droplet and the discharge speed v, the product of the discharge port area So and the distance OH from the discharge port to the tip of the heater, and the distance OH. 19 is a diagram showing the relationship between the result of dividing the ejection speed v by the ejection amount Vd and the distance OH. Figure S1 and Figure S
In No. 2, the singular points a and b are defined, and the distance OH is divided into three areas: an area A equal to or more than a, an area B equal to or less than b, and an area C between a and b.

The characteristic tendency of each region is that in region A, as the distance OH increases, the discharge speed v and the discharge amount Vd are substantially proportional, and v / Vd becomes substantially constant. In the region B, the ejection amount Vd is equal to the ejection area So.
And the distance OH, and the discharge amount Vd is substantially constant in the region C.

The above areas A to C correspond to the ejection amount Vd,
Considering each of the ejection speeds v, it can be defined as follows.

<When Viewed from Discharge Amount Vd> Area A: Section where discharge amount Vd decreases with increase in distance OH Area B: Section where discharge amount Vd increases almost in proportion to distance OH Area C: Discharge Section where the amount Vd is substantially constant with respect to the distance OH <When viewed from the discharge amount v> Distance O over all the sections
Although the ejection speed v decreases with an increase in H, particularly in the region C, the change amount becomes gentle with the change amount.

It is preferable to arrange a front heater in the above-mentioned B region and arrange a rear heater in the B region or the C region.

[0084]

As described above, according to the present invention, two electrothermal transducers are arranged in one nozzle at different distances from the discharge port to the electrothermal transducer, and
An ink jet recording head having substantially the same droplet ejection amount when each of the electrothermal transducers is driven independently, wherein the ejection speed is changed by switching the electrothermal transducers to be driven. The refill frequency increases as the position of the electro-thermal conversion element decreases as the position of the electrothermal transducer approaches the discharge port, contrary to the discharge speed. It is possible to perform ejection under ejection conditions that are optimal for information.

In particular, when the driven electrothermal transducer is switched, by selecting the front heater, it is possible to perform a high discharge power (discharge speed) that improves the landing accuracy and the discharge reliability even if the printing speed is slightly lower. By selecting the rear heater, it is possible to perform high-speed ejection at a high drive frequency, even if the landing accuracy and ejection reliability are somewhat inferior, making it ideal for the purpose or situation of use of the head. It is possible to perform ejection (recording) under appropriate ejection conditions.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a configuration of an ink jet recording head of the present invention.

FIG. 2 is a schematic diagram showing an arrangement of heaters on an element substrate shown in FIG.

FIG. 3 is a graph showing a relationship between a distance from an orifice to a heater and a discharge amount in the discharge characteristics of the ink jet recording head of the present invention.

FIG. 4 is a graph showing a relationship between a distance from an orifice to a heater and a discharge speed in the discharge characteristics of the ink jet recording head of the present invention.

FIG. 5 is a graph showing a relationship between a distance from an orifice to a heater and a driving frequency in the ejection characteristics of the ink jet recording head of the present invention.

FIG. 6 is a graph showing the relationship between the distance from the orifice to the heater and the preliminary ejection interval when the head body is in a normal temperature environment or in a low temperature / low humidity environment, among the ejection characteristics of the ink jet recording head of the present invention. .

FIG. 7 is a block diagram for explaining a first embodiment of the ink jet recording head of the present invention.

FIG. 8 is a flowchart in a case where a basic density print mode is selected as a print mode and a case where a high density print mode is selected in the first embodiment of the present invention.

FIG. 9 is a block diagram for explaining a second embodiment of the ink jet recording head of the present invention.

FIG. 10 is a block diagram for explaining a third embodiment of the ink jet recording head of the present invention.

FIG. 11 is a plan view showing an arrangement of elements constituting an element substrate according to another embodiment of the ink jet recording head of the present invention.

FIG. 12 is a schematic diagram showing an arrangement configuration of the entire element substrate according to another embodiment of the inkjet recording head of the present invention.

FIG. 13 is an equivalent circuit of the element substrate shown in FIG. 11;

FIG. 14 is an equivalent circuit of the overall configuration of the element substrate shown in FIG.

15 is a basic timing chart in an equivalent circuit of the element substrate shown in FIG.

FIG. 16 is a perspective view showing an ink jet head cartridge in which an ink jet head of the present invention and an ink container holding ink to be supplied to the ink jet head are separably connected.

FIG. 17 is a schematic view showing an example of an ink jet recording apparatus equipped with an ink jet recording head according to the present invention.

FIG. 18 is a diagram showing the relationship between the distance OH and the product of the discharge amount Vd of the droplet and the discharge speed v, the product of the discharge port area So and the distance OH from the discharge port to the tip of the heater.

FIG. 19 is a diagram illustrating a relationship between a result obtained by dividing a discharge speed v by a discharge amount Vd and a distance OH.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Common wiring 2, 16 Through hole 2a, 2b Discharge heater 3 Front heater 4 Rear heater 5 Nozzle wall 6, 7 Wiring 8, 9, 10, 11 Switching transistor 12, 13, 14, 15 Ground wiring 17, 18 Signal wiring 19, 20 shift register / latch circuit 21 ground vertical wiring 22 common vertical wiring 23 element 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 Support 42 Common wiring 101 Top plate 104 Nozzle 105 Ink chamber 500 Inkjet head 501 Ink container 2010 Driving motor 2020, 2030 Driving force transmission gear 2040 Leads Liu 2050 carriage shaft 2060 paper pressing plate 2070 platen roller 2080,2090 photocoupler 2100,2170 lever 2110 the cap member 2120 supporting member 2130 sucking means 2140 a cleaning blade 2150 member 2160 a main body support plate 2180 cam

Claims (15)

[Claims] A plurality of electrothermal transducers disposed in an ink flow passage communicating with an ink ejection port, wherein two electrothermal transducers are respectively provided from the ejection port to the electrothermal transducer. Are arranged at different distances from each other, and the discharge amounts of droplets when the two electrothermal transducers are independently driven are substantially the same, and are driven by various kinds of information. An ink jet recording head, wherein the electrothermal transducer is configured to be switched. 2. The ink jet recording head according to claim 1, wherein said various information is a temperature of a head main body. 3. The ink jet recording head according to claim 2, wherein when the temperature of the head body is low or low in humidity, the electrothermal conversion element on the side close to the discharge port is driven. 4. The ink jet recording head according to claim 1, wherein said various information is a print mode. 5. The printing mode includes a large discharge mode for driving both of the two electrothermal transducers and a small discharge mode for driving one of the electrothermal transducers. The inkjet recording head according to claim 4. 6. When the electrothermal conversion element on the side closer to the discharge port in the small discharge amount mode is driven, the mode becomes the discharge reliability emphasis mode or the image quality accuracy emphasis mode, and the electrothermal conversion on the side farther from the discharge port is performed. 6. The ink jet recording head according to claim 5, wherein a high-speed printing mode is set when the element is driven. 7. The ink jet recording head according to claim 1, wherein the various information is a type of a recording liquid. 8. The method according to claim 7, wherein when the type of the recording liquid is an ink that dries more easily than a normal ink, the electrothermal conversion element on the side closer to the discharge port is driven. The inkjet recording head according to the above. 9. The ink jet recording head according to claim 1, wherein the various information is a type of a recording apparatus main body. 10. When the type of the printing apparatus has a driving unit smaller than the size of a driving unit for normal head scanning, the electrothermal conversion element on the side closer to the discharge port is driven. The inkjet recording head according to claim 9, wherein: 11. The ink jet recording head according to claim 1, wherein a driving frequency of the electrothermal transducer is changed according to the switching of the electrothermal transducer. 12. The pre-discharge condition is changed according to the switching of the electrothermal conversion element.
3. The ink jet recording head according to item 1. 13. The PWM table is changed according to the switching of the electrothermal conversion element.
3. The ink jet recording head according to item 1. 14. The discharge timing is changed according to the switching of the electrothermal conversion element.
3. The ink jet recording head according to item 1. 15. A recording medium by removably mounting the ink jet recording head according to claim 1 and reciprocating the same, and ejecting ink from the ink jet recording head according to a desired drive signal. Ink jet recording device that performs recording on paper.