JPH1016227A - Ink emitting method, ink jet recorder and ink jet recording head mounted on the recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink emitting method capable of markedly enhancing refill frequency without lowering the emitting speed of ink droplets in an ink jet recording head, an ink jet recording apparatus and the ink jet recording head mounted on said apparatus. SOLUTION: A plurality of heaters are provided in one nozzle 104 and at least two heaters 3, 4 among them are provided so that the centers of gravity of the heaters 3, 4 are set to positions changed in the distance OH from emitting orifices and, at first, the front heater 3 is driven to emit ink droplets and, next, the rear heater 4 is driven to emit ink droplets and, next, so that the front heater 3 is driven, the front and rear heaters 3, 4 are alternately driven.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jetting method using an ink jet head for jetting ink toward a medium to be jetted (paper, cap, etc.) by inputting an electric signal, and an ink jet for performing the ink jetting method. The present invention relates to a recording apparatus and an inkjet recording head mounted on the apparatus.

[0002]

2. Description of the Related Art Most of ink jet recording apparatuses are known as printing apparatuses in printers, facsimile machines, word processors, copiers, and the like. Among them, a system using thermal energy as energy used for ink ejection, 2. Description of the Related Art An ink jet recording apparatus of a type in which bubbles are generated in ink by energy and the ink is ejected using pressure at the time of the generation of bubbles has been recently spread.

Further, as another application of the ink jet recording apparatus of this type, an ink jet textile printing apparatus which prints a fixed pattern, a picture, a composite image, or the like on cloth has recently been known.

The ink-jet recording head used in the above-described ink-jet recording apparatus uses an electro-thermal conversion element (hereinafter also referred to as a heater) for generating the above-mentioned thermal energy. In the ink flow path (hereinafter, also referred to as a nozzle). In many cases, such an ink jet recording head employs a configuration including one heater corresponding to one nozzle.

In such an ink jet recording head, the distance (hereinafter referred to as OH) from the center of gravity of the heater to the discharge port (orifice) affects the discharge characteristics such as the ink droplet discharge speed and the refill frequency in the ink jet recording head. This is a large factor. Specifically, the ejection speed increases as the OH becomes shorter with respect to the ejection speed of the ink droplet.
It has been found that the frequency tends to decrease as becomes shorter. As is apparent from this, in the structure of the conventional ink jet recording head, the ejection speed of the ink droplet and the refill frequency are in a trade-off relationship with respect to the OH.
OH within the range of usable levels for both refill frequency
Was decided.

[0006]

By the way, in the field of ink jets, further improvement in image quality has been demanded in recent years. As one means for printing a high-resolution image, for example, a configuration in which an image is formed using small ink droplets of 25 pl or less can be given. Usually, when the above-described ink jet recording head discharges small ink droplets, it is performed by reducing the heat energy generated by the heater, so that the discharge speed of the small ink droplets tends to decrease. A decrease in the ejection speed leads to a decrease in the landing accuracy of small ink droplets, and particularly in a high-resolution image, the image quality is more likely to deteriorate than before. Therefore, in such a case, it is desirable that the OH is set to be short in the ink jet recording head in order to prevent a decrease in the ejection speed. However, in the above-described method, since the area of one dot displayed by a small ink droplet is smaller than that of the conventional method, the number of print dots must be increased. Further, as described above, since the refill frequency becomes lower as OH becomes shorter, the use of the above-described method has a problem that the printing speed is lower than that of the related art.

[0007] In addition, a problem may occur with respect to the preliminary ejection performed as part of the ejection recovery process. That is, the preliminary ejection generally involves ejecting ink that is not involved in recording from the inkjet recording head at a predetermined place in the apparatus, and thereby removes the thickened ink and the like in the inkjet recording head and changes the ink ejection state. It keeps good. Such preliminary ejection is normally performed immediately after the power of the apparatus is turned on or at regular intervals during printing. As described above, when printing with small ink droplets or in a low-temperature / low-humidity environment, it is necessary to shorten the interval between preliminary ejections. That is, since the ejection power of the small ink droplet is small, there is a possibility that the thickened ink may not be able to be stably ejected depending on the degree of thickening of the ink due to evaporation of the water at the ejection port.

[0008] Preliminary ejection takes a long time because it is performed in a predetermined non-printing section. 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.

FIG. 8 shows the relationship between the distance OH and the interval between preliminary discharges, along with the above-mentioned discharge characteristics. As shown in the figure, if the OH distance is short, the interval between the preliminary ejections can be greatly increased. As described above, the interval between the preliminary ejections and the ink refill frequency fr have an opposite relationship.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to reduce the refill frequency of a conventional ink jet recording head without reducing the ejection speed of the ink droplets. To improve.

[0011]

According to the present invention, the above-mentioned problems have been solved as follows. That is, a plurality of electrothermal conversion elements for generating thermal energy in the ink flow path of the ink jet recording head are provided, and the plurality of electrothermal conversion elements have different distances between the center of gravity of the electrothermal conversion element and the discharge port. Including two electrothermal conversion elements, the two electrothermal conversion elements are alternately driven to eject ink.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a first ink discharging method according to the present invention, a discharge port which discharges ink, an ink flow path communicating with the discharge port, and a heat source disposed in the ink flow path are provided. A plurality of electrothermal conversion elements for generating energy,
A method of driving the electrothermal conversion element to apply the thermal energy to the ink in the ink flow path to discharge the ink, using an inkjet recording head, wherein the plurality of electrothermal conversion The element includes two electrothermal conversion elements having different distances between the center of gravity of the electrothermal conversion element and the discharge port, and discharges ink by driving the two electrothermal conversion elements alternately.

In a second ink discharging method according to the present invention, an ink discharge portion serving as a portion for discharging ink, an ink flow passage communicating with the discharge opening, and thermal energy used for ink discharge are transferred to the ink flow passage. A plurality of electrothermal transducers disposed in the ink flow path for applying to ink, and having a first mode for discharging large ink droplets and a second mode for discharging small ink droplets An ink discharging method using a head, wherein the plurality of electrothermal transducers include two electrothermal transducers having different distances from the center of gravity of the electrothermal transducer and the ejection port, and the two or more electrothermal transducers are in the second mode. The method is characterized in that ink is ejected by using two electrothermal conversion elements alternately.

In the second ink discharging method, the first mode is characterized in that ink is discharged simultaneously using the two electrothermal transducers. Further, immediately after shifting from the first mode to the second mode, of the two electrothermal transducers, the electrothermal transducer having the center of gravity of the electrothermal transducer farther from the discharge port is driven first. It is characterized by.

[0015] In the first and second ink discharging methods, the amount of ink discharged when the two electrothermal transducers are independently driven is substantially the same. Further, of the two electrothermal transducers, the electrothermal transducer starts driving from the electrothermal transducer closer to the discharge port. Further, the center of gravity of the two electrothermal conversion elements is disposed in the A region and the B region, respectively.

An ink jet recording apparatus according to the present invention comprises:
A discharge port that discharges ink, an ink flow path communicating with the discharge port, and a plurality of electrothermal conversion elements for generating thermal energy disposed in the ink flow path; An ink jet recording apparatus using an ink jet recording head for discharging an ink by driving the electrothermal transducer to apply the thermal energy to the ink in the ink flow path, wherein the plurality of electrothermal transducers is an electrothermal transducer. It is characterized by including two electrothermal conversion elements having different distances between the center of gravity of the conversion element and the discharge port, and having a drive control means for alternately driving the two electrothermal conversion elements.

According to another ink jet recording apparatus of the present invention, there is provided a discharge port which is a portion for discharging ink, an ink flow path communicating with the discharge port, and a heat energy used for ink discharge being supplied to the ink in the ink flow path. And a plurality of electrothermal transducers disposed in the ink flow path for applying ink to the ink jet recording head, and having a first mode for discharging large ink droplets and a second mode for discharging small ink droplets. Wherein the plurality of electrothermal transducers include two electrothermal transducers having different distances between the center of gravity of the electrothermal transducer and the ejection port, and the two electrothermal transducers are in the second mode. It has a drive control means for alternately driving the electrothermal conversion elements.

An ink jet recording head according to the present invention has a discharge port as a portion for discharging ink, an ink flow path communicating with the discharge port, and a plurality of thermal energy sources arranged in the ink flow path for generating thermal energy. And an electrothermal conversion element, wherein the electrothermal conversion element is driven to discharge the ink by applying the thermal energy to the ink in the ink flow path, thereby discharging the ink. The conversion element includes two electrothermal conversion elements having different distances between the center of gravity of the electrothermal conversion element and the discharge port, and the two electrothermal conversion elements are driven alternately.

In another ink jet recording head according to the present invention, there is provided a discharge port as a portion for discharging ink, an ink flow path communicating with the discharge port, and a heat energy used for ink discharge in the ink flow path. And a plurality of electrothermal transducers disposed in the ink flow path for applying ink to the ink jet recording head, and having a first mode for discharging large ink droplets and a second mode for discharging small ink droplets. Wherein the plurality of electrothermal transducers include two electrothermal transducers having different distances between the center of gravity of the electrothermal transducer and the discharge port, and the two electrothermal transducers alternate in the second mode. Is driven.

[0020]

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

First, the configuration of the 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 nozzle arrangement density 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 the nozzle wall 5.
By joining the element substrate 23 and the top plate 101 as shown, the nozzles 104 and the ink chambers 105 are formed.

FIG. 2 is a schematic diagram showing the arrangement of heaters on the element substrate of the ink jet recording head. Two heaters of the front heater 3 and the rear heater 4 are arranged side by side in one nozzle 104 between the nozzle walls 5, and the distance OH from the center of gravity of the heater to the discharge port (orifice) is different. I have.

Each of the heaters 3 and 4 has a through hole 2
Are connected to the common wiring 1 under the interlayer insulating films below the heaters 3 and 4, and a voltage is applied from the common wiring 1. Wirings 6 and 7 are connected to front heater 3 and
It is connected to the rear heater 4.

That is, from the ink chamber 105 to the nozzle 10
The ink is supplied to the nozzles 4, and the heaters 3 and 4 provided in the nozzle 104 generate heat by a signal current, and heat and foam the ink in the nozzle 104, and the ink in the nozzle 104 is directed from the orifice 40 to the recording medium by the foaming. Discharge.

In this case, when two heaters 3 and 4 having substantially the same size and the same length are arranged in the nozzle 104 and the two heaters are driven independently of each other, the small liquid The ejection amounts of the droplets are set to be substantially the same.

Next, the discharge characteristics of the small droplets of the above-described ink jet recording head will be described with reference to FIGS.

The distance OH between the center of gravity of the heater and the discharge port (orifice) is a large factor that affects the discharge characteristics. When the distance OH is used as a parameter, the ejection amount Vd of the droplet is
It has been found by examination that the discharge speed v and the refill frequency fr have characteristics as described below.

In other words, when the front and rear heater sizes are the same, driving the rear heater 4 farther from the discharge port (longer OH) results in a lower refill frequency fr as shown in FIG. It will be 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 becomes possible. However, as shown in FIG. 4, the ejection speed v becomes low. Conversely, when the front heater 3 closer to the discharge port (shorter OH) is driven alone, the discharge speed v is significantly improved, but on the other hand,
As shown in FIG. 5, the refill frequency fr decreases. As described above, it has been found that the discharge speed v and the refill frequency fr have an opposite relationship. At this time, if the distance OH is within the range as shown in FIG.
In contrast, any OH may be selected.

Depending on the setting method, for example, FIG.
The heater size of the rear heater 4 is slightly larger than the heater size of the front heater 3 by setting OH distances such as B2 and A2 shown in FIG. .), It is possible to make the discharge amounts when the respective heaters are driven independently almost the same, and conversely, the distance OH such as B1, A1 shown in FIG.
May be set to make the heater size of the front heater 3 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.

FIG. 6 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. FIG. 7 is a diagram showing the relationship between the result of dividing the ejection speed v by the ejection amount Vd and the distance OH. 6 and 7, the singular points a and b are defined, and the distance OH is set to the area A equal to or more than a, the area B equal to or less than b, and the area C equal to between a and b.
Are divided into three regions.

The characteristic tendency of each region is that in region A, the discharge speed v and the discharge amount Vd are substantially proportional to each other as the distance OH increases, 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 discharge amount Vd,
Considering each of the ejection speeds v, it can be defined as follows.

<When Viewed from Discharge Amount Vd> Area A: A section where the discharge amount Vd decreases as the distance OH increases. Area B: A section where the discharge amount Vd increases almost in proportion to the 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.

As shown in FIG. 6, the ejection amount Vd of the ink droplet
Is a maximum value at a certain distance OH, and decreases as the distance from the predetermined distance OH increases. Therefore, the rear heater 4 is disposed in the area A and the front heater 3 is disposed in the area B so that the distance OH of each heater is symmetric with respect to the distance OH that is a bending point. 4
And the discharge amount Vd by driving the front heater 3 can be made almost the same.

Next, a method of driving the above-described ink jet recording head will be described.

(Embodiment 1) In this embodiment, basically, first, the front heater 3 is driven to eject ink droplets.
The front heater 3 and the rear heater 4 are alternately driven such that the rear heater 4 is driven to eject ink droplets, and then the front heater 3 is driven.

By driving each heater in this manner, the refill frequency can be improved without lowering the ejection speed.

The behavior and discharge characteristics of the meniscus near the discharge port when driven in this manner will be described below.

First, the front heater 3 is driven to eject ink droplets at a pressure at which the ink foams on the heater surface.
In this case, since the distance of the front heater 3 is short from the ejection port, the flow resistance in the front part of the foamed portion (in this case, the inertance forward from the center of gravity of the heater in this case) is small, so that the ejection speed v of the ink droplet is high. After the discharge, the bubbles formed on the heater surface shrink, so that the meniscus at the discharge port is drawn. Also in this case, since the distance of the front heater 3 is short from the ejection port, the time required for the meniscus to return to before the ejection becomes longer. In other words, the refill frequency fr decreases.

Here, if the driving frequency of the nozzle is 12K
Hz, if the ink is continuously ejected from this nozzle, the above-mentioned refill frequency fr is 9 KH.
Since it is only about z, the meniscus cannot return completely. When the same front heater 3 is driven without switching the heater to be driven in this state, the amount of ink in front of the heater is reduced, and a droplet having a small discharge amount Vd is discharged. Further, since the meniscus recedes, the discharge power of the heater also increases, so that solid printing may result in faint printing, which degrades image quality.

However, in the present invention, the rear heater 4 is driven even when the meniscus cannot be completely returned, so that the discharge amount and the discharge speed are substantially the same as those of driving the front heater by the operation described below. It will be.

When the meniscus is stable, the rear heater 4
Is driven, the discharge amount Vd is not much different from the case where the front heater 3 is driven as described above, but the discharge speed v is largely reduced. But,
When the rear heater 4 is driven and ejected in a state where the meniscus is retracted, the ejection speed v is increased due to the effect that the distance between the meniscus and the heater is further reduced. It is conceivable that the flat part of the meniscus portion where the foaming force acts is narrowed, and thus the same effect is obtained as the discharge port diameter is reduced.However, this also increases the discharge speed v. It is presumed to have contributed. Further, since the distance to the discharge port in front of the heater is increased, stable discharge is achieved without a decrease in the discharge amount Vd.

After the discharge by the rear heater 4 described above, the bubbles formed on the rear heater surface are contracted, and the meniscus of the discharge port is drawn in. In this case, the distance of the center of gravity of the rear heater 4 is determined by the distance of the discharge port. , The retreat amount of the meniscus becomes small, and as a result, the refill time, that is, the time until the meniscus returns to the state before ejection becomes short. In other words, the refill frequency fr increases.

Subsequently, when the front heater 3 discharges at the next timing, the meniscus has already returned to the vicinity of the expected position, and therefore, even after the discharge is continuously repeated, stable discharge is performed. In addition, since the ejection speed v increases, the interval between the preliminary ejections can be increased.

(Embodiment 2) In Embodiment 1, the case of continuous ejection of small ink droplets has been described. However, if the ink jet recording head of Embodiment 1 can use the front and rear heaters simultaneously, large ink droplets can be ejected. This makes it possible to perform gradation expression.

This embodiment shows a case where gradation is expressed by the ink jet recording head according to the present invention.

The ink jet recording head according to this embodiment has two modes, a large ink droplet ejection mode for ejecting large ink droplets and a small ink droplet ejection mode for ejecting small ink droplets.

The following describes a driving method in the case where printing is performed by mixing large dot mode printing for discharging large ink droplets and small dot mode printing for discharging small ink droplets.

FIG. 9 is a diagram showing data processing when printing is performed by mixing large dots and small dots.
9 shows ejection data, and FIG. 9B shows a heater driven by the image data shown in FIG. 9A.

In the figure, F indicates when only the front heater is driven, B when only the rear heater is driven, and F + B when the front and rear heaters are driven. Further, small dots are indicated by small circles 51 and large dots are indicated by large circles 52. FIGS. 9A and 9B show a state where the ink is ejected from left to right in the figure.

Which heater (F, B or F + B) should be driven for each nozzle is determined by data processing. The basic matter of how to determine this will be described below.

For one line of ejection data (not necessarily image data), if it is the next small dot data of a pixel with no data at a certain nozzle, small ink droplets are ejected by the front heater as in the first embodiment. . By doing so, an excellent ejection speed can be obtained.

When printing a small dot following a small dot, B is set after F, and F is set after B. In this case, as described in the first embodiment, in the former case, both the refill frequency fr and the ejection speed v are good.

When printing a small dot immediately after a large dot, B is set (F + B → B). This way,
The refill frequency fr increases, and the ejection speed v increases.

That is, the meniscus has a long return time immediately after the ejection of the large dot (F + B) or the small dot (F). Therefore, when printing a small dot, the refill frequency can be increased by ejecting the dot B. it can.

As described above, according to the present invention, even when gradation expression is performed, excellent ejection speed and refill frequency can be secured, and gradation expression with excellent image quality can be performed.

In the present invention, each heater is driven by driving the heater to be driven by drive control means of the ink jet recording apparatus, or by providing a drive switching means in the ink jet recording head. It is also possible.

[0061]

Since the present invention is configured as described above, the following effects can be obtained. That is, even when a small ink droplet is ejected, the refill frequency can be significantly improved without lowering the ejection speed of the ink droplet, and the interval between preliminary ejections can be increased.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an ink jet recording head.

FIG. 2 is a schematic diagram illustrating an arrangement of heaters on an element substrate of the inkjet recording head.

FIG. 3 is a diagram illustrating a relationship between a discharge amount Vd of a droplet and a distance OH.

FIG. 4 is a diagram showing a relationship between a droplet discharge speed v and a distance OH.

FIG. 5 is a diagram illustrating a relationship between a refill frequency fr and a distance OH.

FIG. 6 is a diagram showing a relationship between a droplet discharge amount Vd, a discharge speed v, and a distance OH.

FIG. 7 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.

FIG. 8 is a diagram illustrating a relationship between a preliminary ejection interval and a distance OH.

FIG. 9 is a diagram showing data processing when printing is performed by mixing large dots and small dots.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Common wiring 2 Through hole 3 Front heater 4 Rear heater 5 Nozzle wall 6, 7 Wiring 23 Element substrate 40 Orifice 41 Support 101 Top plate 104 Nozzle 105 Ink chamber

Claims (11)

[Claims] A discharge port that discharges ink;
An ink flow path communicating with the discharge port; and a plurality of electrothermal conversion elements for generating thermal energy disposed in the ink flow path. An ink ejection method using an ink jet recording head that ejects ink by applying the thermal energy to ink in the ink, wherein the plurality of electrothermal transducers are a distance between the center of gravity of the electrothermal transducer and the ejection port. Includes two different electrothermal transducers, and alternately drives the two electrothermal transducers to eject ink. 2. A discharge port which discharges ink,
An ink flow path communicating with the discharge port, and a plurality of electrothermal conversion elements arranged in the ink flow path for applying thermal energy used for ink discharge to ink in the ink flow path,
And an ink ejection method using an ink jet recording head having a first mode for ejecting large ink droplets and a second mode for ejecting small ink droplets, wherein the plurality of electrothermal conversion elements are electrothermal conversion elements. An ink discharge method comprising: two electrothermal conversion elements having different distances between the center of gravity of the element and the discharge port, and in the second mode, alternately using the two electrothermal conversion elements to discharge ink. . 3. The ink discharging method according to claim 2, wherein in the first mode, ink is discharged using the two electrothermal transducers simultaneously. 4. Immediately after shifting from the first mode to the second mode, among the two electrothermal transducers, the electrothermal transducer having the center of gravity of the electrothermal transducer farther from the discharge port is first used. 4. The ink discharging method according to claim 3, wherein the ink is ejected. 5. The ink discharge method according to claim 1, wherein the ink discharge amounts when the two electrothermal transducers are independently driven are substantially the same. 6. The ink discharging method according to claim 1, wherein, of the two electrothermal converting elements, the driving is started from the electrothermal converting element whose center of gravity is closer to the ejection port. 7. The ink discharging method according to claim 5, wherein the centers of gravity of the two electrothermal transducers are arranged in an A region and a B region, respectively. 8. A discharge port for discharging ink,
An ink flow path communicating with the discharge port; and a plurality of electrothermal conversion elements for generating thermal energy disposed in the ink flow path. An ink jet recording apparatus using an ink jet recording head that ejects ink by applying the thermal energy to the ink inside, wherein the plurality of electrothermal transducers are a distance between the center of gravity of the electrothermal transducer and the ejection port. Includes two different electrothermal transducers, and a drive control unit for alternately driving the two electrothermal transducers. 9. An ejection port for ejecting ink,
An ink flow path communicating with the discharge port, and a plurality of electrothermal conversion elements arranged in the ink flow path for applying thermal energy used for ink discharge to ink in the ink flow path,
And an ink jet recording apparatus using an ink jet recording head having a first mode for discharging large ink droplets and a second mode for discharging small ink droplets, wherein the plurality of electrothermal conversion elements are electrothermal conversion devices. Ink jet recording comprising two electrothermal conversion elements having different distances between the center of gravity of the element and the discharge port, and having drive control means for alternately driving the two electrothermal conversion elements in the second mode. apparatus. 10. An ink ejection portion serving as an ink ejection portion, an ink flow passage communicating with the ejection opening, and a plurality of electrothermal conversion elements for generating thermal energy disposed in the ink flow passage. An ink jet recording head that ejects ink by driving the electrothermal conversion element to apply the thermal energy to the ink in the ink flow path, wherein the plurality of electrothermal conversion elements are electrothermal conversion elements. An ink jet recording head comprising two electrothermal conversion elements having different distances between the center of gravity of the element and the discharge port, and the two electrothermal conversion elements are driven alternately. 11. An ink discharge portion serving as an ink discharge portion, an ink flow passage communicating with the discharge opening, and an ink flow passage for applying thermal energy used for ink discharge to ink in the ink flow passage. And a plurality of electrothermal transducers disposed therein, and an ink jet recording head having a first mode for discharging large ink droplets and a second mode for discharging small ink droplets. The heat conversion element includes two electrothermal conversion elements having different distances between the center of gravity of the electrothermal conversion element and the discharge port, and the two electrothermal conversion elements are alternately driven in the second mode. Inkjet recording head.