JPH05116301A - Ink jet recording method, ink jet record head, and ink jet recording device - Google Patents

Abstract

PURPOSE:To enable high speed recording with uniform ink discharge all the time in an ink jet recording method wherein bubbles formed in ink by heat energy break into the outside air so that ink particles can be emitted. CONSTITUTION:A bubble 6 generated in the neighborhood of a heater 2a, as shown in (b), supplied with a pulse for heat generation expands as shown in (c) and bursts when exposed to the outside air as shown in (d). Thereafter, as shown in (e), a bubble 6a is generated in the neighborhood of a heater 2b to separate an ink particle 7a from the ink in an ink passage 12 so that the ink particle 7a can be emitted as shown in (f).

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 method, an ink jet recording head and an ink jet recording apparatus for ejecting ink by utilizing heat energy.

[0002]

2. Description of the Related Art An ink jet recording method in which ink droplets are ejected and deposited on a recording medium to form an image is capable of high-speed recording, relatively high recording quality, and low noise. Have advantages. Further, this method has many excellent advantages that color images can be recorded relatively easily, it can be recorded on plain paper, and that the apparatus can be easily downsized.

A recording apparatus using such an ink jet recording method is generally provided with an ejection port for ejecting ink as a flying ink drop, an ink path communicating with this ejection port, and a part of this ink path. And a recording head having an energy generating unit that gives ejection energy for ejecting the ink in the ink path. For example,
Japanese Patent Publication No. 61-59911, Japanese Patent Publication No. 61-59912
No. 61-59913 and 61-5991
Each of the gazettes of No. 4 discloses a method in which an electrothermal converter is used as the energy generating means, and the thermal energy generated by the electric pulse is applied to the ink to eject the ink.

That is, in the recording methods disclosed in the above publications, the ink subjected to the action of thermal energy causes a state change accompanied by a sharp increase in volume, and the action force based on this state change causes the recording. Ink is ejected from the ejection port at the tip of the head portion, and the ejected ink droplets adhere to the recording medium to form an image. According to this method, since the ejection openings in the recording head can be arranged at a high density, it is possible to record an image of high resolution and high quality at high speed. A recording apparatus using this method is a copying machine, It can be used as information output means in printers, facsimiles and the like.

On the other hand, as an ink jet recording method which uses heat energy but does not have any realization conditions, there is a method described in JP-A-54-161935. In this publication, as shown in FIG. 1, the cylindrical heating element 30 gasifies the ink 31 in the liquid chamber (FIG. 1, (a)).
The gas 32 is ejected together with the ink droplet 33 from the ink ejection port (FIGS. 1B and 1C). According to this method
The gas 32 is ejected in the form of fine droplets from or near the discharge port, resulting in poor image quality. It is recognized that the bubbles in this publication are bubbles formed by nucleate boiling.

The same nucleate boiling, for example, Japanese Patent Laid-Open No.
According to the publication No. 1-185455, as shown in FIG. 2, the heating element head 42 heats the liquid ink 44 filled in the minute gap 43 between the heating element head 42 and the plate-shaped member 41 having the small opening 40 ( 2A and 2B, the generated bubble 45 causes the ink droplet 46 to fly from the small opening 40, and the gas that has formed the bubble 45 whose volume is rapidly increasing due to nucleate boiling is also small opening. It is ejected from 40 (FIG. 2C) to form an image on the recording paper.

Furthermore, Japanese Patent Laid-Open No. Sho 6-1994 discloses the same nucleate boiling.
In JP-A 1-249768, as shown in FIG. 3, thermal energy is applied to the liquid ink 50 to form a considerably large bubble, and an ink droplet 58 is generated based on the expansion force of the bubble.
There is simply described an ink jet recording apparatus that forms and flies, and at the same time ejects gas that has formed bubbles also into the atmosphere from the large opening 52.

However, the above-mentioned JP-A-54-1619 is used.
No. 35, No. 61-185455, No. 61-24976.
The configuration common to No. 8 is that the gas forming bubbles is ejected as fine ink droplets into the atmosphere together with the ejection of the main ink droplets. As a result, the jetting of this gas gasifies the ink to generate splashes or mists, which may result in background stains on the recording paper or stains inside the apparatus.

Further, for example, Japanese Patent Laid-Open No. 61-197246 discloses a thermal transfer recording apparatus using a modified method of the conventional inkjet recording method using thermal energy. That is, in this apparatus, as shown in FIG. 4, the ink 62 held by the plurality of holes 61 provided in the recording medium 60 is heated by the recording head 64 having the heating element 63, and the ink droplet 65 is recorded. It is ejected onto the medium 66. This recording apparatus discharges ink only once and, in addition, it is difficult to completely bring the recording medium 60 and the heating element 63 into close contact with each other. Therefore, as compared with the inkjet recording method using the conventional recording head having a discharge port. However, there is a problem that the thermal efficiency is likely to decrease and it is not suitable for high speed recording.

[0010]

BACKGROUND OF THE INVENTION In order to solve the problems of the ink jet recording method as described above, the applicant of the present invention has taken advantage of the fact that bubbles caused by film boiling generated by heating ink for ejection are exposed to the outside air near the ejection port. An ink jet recording method (hereinafter, this method is also referred to as a continuous discharge method) in which discharge is performed by communicating with each other has been proposed (Japanese Patent Application No. 2-112832,
Japanese Patent Application No. 2-112833, Japanese Patent Application No. 2-112834
No. 2, Japanese Patent Application No. 2-114472).

According to the above continuous discharge method, the gas forming the bubbles does not jet together with the discharged ink droplets, so that the generation of splash and mist is reduced,
It is possible to prevent background stains on the recording medium and stains inside the apparatus.

Further, as a basic operation of the above-mentioned continuous discharge method, there is a principle that all the ink on the discharge port side of the portion where bubbles are generated is discharged as ink droplets. Therefore, the amount of ejected ink can be determined by the structure of the recording head, such as the distance from the ejection port to the bubble generating portion. As a result, according to the above-described continuous discharge method, it is possible to perform stable discharge of the discharge amount without being affected by the change in the ink temperature.

The above-mentioned continuous discharge method will be described below with reference to FIGS.

FIGS. 5 (a) and 5 (b) show a recording head and a discharging method suitable for applying the above-mentioned continuous discharge method. Two examples of specific ink path constitutions of this recording head are shown. .. However, it goes without saying that the present invention is not limited to this configuration.

The ink path structure shown in FIG. 5 (a) comprises a heating resistance layer (heater) 2 on a substrate (not shown), and a partition or a top plate is provided on this substrate to form a common liquid chamber C. And the ink path B is formed. At the same time, the ejection port 5 is formed at the end of the ink path B. E1 and E2 are
A selection electrode and a common electrode for applying a pulsed electric signal to the heater 2 are shown respectively. Further, D is a protective layer.

In response to the application of the electric signal based on the recording data via the electrodes E1 and E2, the heater 2 between the electrodes E1 and E2 generates a rapid temperature rise that causes a vapor film in a short time. (About 300 ° C.), whereby bubbles 6 are generated. The bubbles 6 grow and eventually communicate with the atmosphere at the end A of the ejection port 5 on the substrate side. After this communication, stable ejected ink droplets (broken line 7) are formed.

In this ejection, since the bubble 6 does not completely block the ink path B during the growth process (the ink in the ink path B is continuous with the ink protruding from the ejection port 5), the refill for the subsequent ejection is performed. Be done promptly,
Further, since the heat of the bubbles having a relatively high temperature of 300 ° C. or higher is also released to the outside air, a large problem of heat storage (ink viscosity lowering due to heat storage and destabilization of bubble formation) does not occur, and each heater is driven. The duty can be increased.

Although the common liquid chamber C is not shown in FIG. 5B, the ink passage B is formed into a bent shape, and a heating resistor portion (heater) 2 is provided on the substrate surface of the bent portion. There is. The discharge port 5 has a shape that reduces its cross-sectional area in the discharge direction, and has an opening facing the heater 2. The discharge port 5 is formed in the orifice plate OP.

Also in FIG. 5 (b), a vapor film (about 300.degree. C.) is generated to generate bubbles 6 as in the structure of FIG. 5 (a).
To generate. By generating the bubbles, the ink in the thickness portion of the orifice plate OP is pushed in the ejection direction, and the ink in the portion is diluted. After that, the bubbles 6 communicate with the atmosphere in the range from the outer peripheral edge A1 of the discharge port 5 to the discharge port vicinity region A2 on the inner side. At this time, since the growth of the bubbles 6 does not block the ink path, the ink that does not need to go in the ejection direction can remain as a continuous body with the ink in the ink path B, and the ejection amount of the ink droplet 7 can be reduced. It is possible to achieve stabilization and stabilization of the discharge speed.

According to such a continuous discharge method, bubble growth in the vicinity of the discharge port can be performed rapidly and surely, so that the refilling property of the ink path in the non-blocking state is also assisted, and high stable high speed recording is possible. Can be achieved. Further, by communicating the air bubbles with the atmosphere, the defoaming process of the air bubbles is eliminated, and it is possible to prevent the heater and the substrate from being damaged by cavitation.

The above-described communication between the bubbles and the atmosphere associated with the ink ejection can be realized basically by bringing the position of the heater 2 closer to the ejection port 5. However, the conditions that ensure the suppression of the above-described splash and the like and the stabilization of the discharge amount, which are preferable when applied to the configurations shown in FIGS. 5A and 5B, are listed below.

The first condition is that the bubbles communicate with the outside air under the condition that the internal pressure of the bubbles is lower than the outside pressure.

That is, by causing the bubbles to communicate with the outside air under the condition that the internal pressure of the bubbles is lower than the outside air pressure, the ink scattering near the discharge port, such as splash, which occurs when the bubbles are communicated under the condition that the inside pressure of the bubbles is higher than the outside pressure. In comparison with the case where the above two pressures are equal, the force of drawing unstable ink into the ink passage at the time of ejection is small, but works more stably, and more stable ink ejection and prevention of unnecessary ink scattering Can be planned.

As a condition different from the above-mentioned first condition, the second condition that the bubble and the outside air are communicated with each other under the condition that the first differential value of the moving speed of the bubble at the end portion on the discharge port side is negative, and the discharge condition Distance L _a from the discharge port side end of the energy generating means to the bubble discharge port side end and from the end of the discharge energy generating means on the side opposite to the discharge port to the end on the side opposite to the bubble discharging port. It is more preferable that the bubble and the outside air are communicated with each other by satisfying the third condition that the distance L _b of is equal to L _a / L _b ≧ 1 or both of them.

The first condition will be described in more detail with reference to FIGS.

The relationship between the elapsed time t from foaming and the bubble volume V and the bubble internal pressure P is as shown in FIG. 6, but in reality, since the bubbles communicate with each other during their growth, these relations are As shown in FIG. That is, in FIG. 7, the bubbles communicate with the outside air at time t = tb (t1 ≦ tb: t1 is the time when the bubble internal pressure p becomes equal to the pressure of the outside air). The first condition is a condition that the pressure P inside the bubble is smaller than the pressure (OATM) of the outside air at this time.

When the ink is ejected under this condition, compared with the case where the bubble is communicated with the outside air and the ink droplet is ejected under the condition that the pressure P inside the bubble is higher than the outside pressure (the gas is ejected into the atmosphere), As described above, it is possible to prevent the recording paper and the inside of the device from being contaminated by the mist and splash of ink. Further, when the bubble internal pressure P is made smaller than the atmospheric pressure to communicate with each other in this way, the bubble can be communicated with the outside air after the volume of the bubble is relatively increased. Thereby, sufficient kinetic energy can be transmitted to the ink, and the effect of increasing the ejection speed can also be obtained.

The recording head satisfying the first condition is provided, for example, at a position where the position of the heater 2 is close to the direction of the ejection port 5 in FIG. This is the simplest method for communicating air bubbles with the outside air. However, the first condition cannot be satisfied simply by bringing the heater 2 closer to the ejection port 5. That is, in order to satisfy the above conditions, the amount of heat energy generated by the heater (depending on the heater configuration, forming material, driving conditions, area, heat capacity of the substrate on which the heater is provided, etc.), ink physical properties, and various parts of the recording head By appropriately setting the size (the distance between the discharge port and the heater, the width and height of the discharge port and the liquid passage), it is possible to communicate with the outside air in a state where the first condition is satisfied.

Specifically, for example, the ink path shape contributes to the communication between the bubbles and the atmosphere as follows. In other words, although the width of the ink path shape is almost determined by the shape of the thermal energy generating element used, the specific relationship is often set by empirical rules. However, it has been clarified that the height of the ink path affects the conditions for the communication of the bubbles with the atmosphere. Therefore, in order to reduce the influence of the environment and the like on the outside and to further stabilize the communication between the air bubbles and the atmosphere, the width W of the ink path is
It is preferable to lower the height H of the ink path (H> W).

Further, for example, when the time of communication is viewed in terms of the volume of bubbles, the maximum volume of bubbles that will be reached when the bubbles do not communicate with the outside air, or 70% or more, and more preferably 80% or more of the maximum volume. It is preferable that the bubbles communicate with the outside air when the volume is reached.

Next, the above-mentioned second condition, which is a different expression of the above-mentioned first condition, that is, the condition that the bubble communicates with the outside air when the first differential of the expansion velocity of the bubble becomes negative will be described.

FIG. 8 shows changes in the bubble volume V and the bubble internal pressure P and changes in the bubble expansion velocity dV / dt from the time when the ink starts foaming until the bubble communicates with the outside air.
Shown in.

From this figure, it is possible to know the magnitude relationship between the internal pressure and the external pressure of the bubble by obtaining the first derivative of the expansion velocity, that is, the second derivative of the volume V d ² V / dt ² . That is, the expansion velocity dV / dt of the bubble increases during the period of d ² V / dyt ² > 0, and the velocity dV / dt decreases when d ² V / dt ² <0. Therefore, when d ² V / dt ² = 0, it can be said that the bubble internal pressure P becomes equal to the external atmospheric pressure.
That is, when d ² V / dt ² > 0, the bubble internal pressure P is higher than the external pressure, and when d ² V / dt ² ≦ 0, the bubble internal pressure P is equal to or lower than the external pressure.

Referring to FIG. 8, from the start of foaming t = t ₀ to t = t ₁ , the bubble internal pressure P is higher than the external pressure d.
² V / dt ² > 0, and the internal pressure of the bubble is equal to or lower than the external atmospheric pressure until t = t _b from t = t ₁ until the bubble communicates with the external air, and d ² V / dt ² ≦ 0. Normally, this general theory holds, but since the bubble volume changes due to the ink material or the resistance of the ink path, there may be a slight difference in the relationship with the external atmospheric pressure.
Therefore, as conditions other than the first condition, d ² / V / dt ² <
It is preferable to satisfy 0, and the sum of the first condition and the second condition becomes more preferable.

As described above, the second derivative of the volume V is d ² V /
When dt ² <0, that is, when the first derivative of the expansion velocity is negative,
By allowing the bubbles to communicate with the outside air, the bubbles can communicate with each other under the condition that the pressure inside the bubbles is lower than the outside pressure.

According to the above-mentioned second condition, when the air bubble and the outside air are communicated with each other, the ink in the vicinity of the communication portion is ejected from the ink and is excessively accelerated so that the ink is separated from the main ink droplet. You can also do it. When the above separation occurs, it becomes noticeable that the ink in the vicinity thereof is splashed in the form of splash, or is scattered as a mist,
Moreover, in a high-density ejection port arrangement, ejection failure may occur due to ink adhering to the ejection port surface.
Can be settled according to the conditions.

[0037]

The present invention further secures the above-mentioned advantages of the above continuous discharge system, and
An object of the present invention is to provide an inkjet recording method, an inkjet recording head, and an inkjet recording device that enable high-speed recording with a constant discharge amount.

[0038]

Therefore, according to the present invention,
In an inkjet recording method using a recording head having an ejection port for ejecting ink and an ink path communicating with the ejection port, thermal energy is applied to a predetermined portion of the ink path to cause the ink to have a first Of the bubbles, a step of ejecting ink from the ejection port based on the generation of the first bubble, a step of communicating the first bubble with outside air at the ejection port, and Generating a second bubble in the ink after the first bubble communicates with the outside air by applying thermal energy from the predetermined portion of the ink path to the ejection port side. Characterize.

Further, an ejection port for ejecting ink,
In the ink path, an ink path communicating with the ejection port, a first thermal energy generation unit provided in the ink path for applying thermal energy to the ink to generate bubbles in the ink, A second unit provided on the ejection port side by the first thermal energy generation unit for applying thermal energy to the ink to generate bubbles in the ink.
The first heat energy generating means is used for communicating the air bubbles with the outside air in the process of ejecting ink from the ejection ports by the air bubbles generated by the action of the heat energy. The second thermal energy generating means is used to generate bubbles in the ink after the communication by the action of the thermal energy.

Further, in an ink jet recording apparatus for recording on a recording medium by ejecting ink, an ejection port for ejecting ink, an ink path communicating with the ejection port, and an ink path provided in the ink path are provided. And a first thermal energy generating means for applying thermal energy to the ink to generate bubbles in the ink, and a first thermal energy generating means provided in the ink passage on the ejection port side. , A recording head having a second thermal energy generating means for applying thermal energy to the ink to generate bubbles in the ink, and the thermal energy generated by driving the first thermal energy generating means. First driving means for communicating the bubble with the outside air in the process of ejecting the ink from the ejection port by the bubble generated by the action of The second heat energy generating means is driven by the action of thermal energy to the generated, characterized in that comprises a second driving means for generating a bubble in the ink after passing through the communication.

An ink jet recording apparatus for forming a bubble by film boiling by generating thermal energy, communicating the bubble with the outside air, and ejecting an ink droplet from an ejection port,
It is characterized in that it has a separating means which acts in the vicinity of the ejection port and causes a sudden change in the physical properties of the ink ejected from the ink path and the ink in the ink path.

The separating means of the present invention includes all that cause a change in the physical properties of the ink. In addition to the vaporized bubble forming means (nucleate boiling may be used, preferably film boiling) as well as the exemplified Peltier element. It may be a rapid cooling means such as.

In any case, the present invention accelerates the separation of the ink by imparting a physical property change to the ink itself remaining in the ink path with respect to the ink ejected after communicating the bubbles outside the ink path. The droplets can be formed more quickly and stably.

[0044]

With the above arrangement, the first thermal energy generating means causes the first bubbles generated in the ink to grow,
During the process of ejecting ink by this growth, the bubbles communicate with the outside air. Then, the ink in the ejection process in which the bubbles are communicated is separated by the second bubbles generated by the second thermal energy generating means, and ejected ink droplets are formed. As a result, the speed of the ejected ink droplets is improved and stabilized, and the ink that adheres to and remains on the ink path wall can be eliminated.

[0045]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 9A is an exploded perspective view showing the structure of the recording head according to the embodiment of the present invention.

As shown in these figures, the partition wall 8 for forming the ink 12 and the common liquid substance 10 are formed on the first substrate 1 provided with the heater 2a as the first heating means. An outer wall 9 is provided. This first substrate 1
Then, the second substrate 4 provided with the heater 2b as the second heating means is bonded by pressure bonding or the like. That is, the substrate 4 is bonded to the partition wall 8 and the outer wall 9 on the substrate 1. As a result, the ink passage 12 and the common liquid chamber 10 are formed,
Each ink passage 12 has a heater 2a at its bottom,
The heater 2b is arranged on the upper part thereof. These heaters 2
Each of a and 2b generates heat by being driven by a current supplied through an electrode (not shown).

FIG. 9B is a sectional view taken along the line AA 'of the recording head shown in FIG. 9A.

As is clear from the figure, the position of the discharge port 5, that is, the end portions of the substrates 1 and 4 and the heater 2 respectively.
The distance between a and the heater 2b is set larger in the former case.

FIG. 10 is a schematic cross-sectional view showing the process from the heating of the ink in the ink passage to the ejection of the ink droplet from the ejection port in the ink jet recording method using the recording head of this embodiment.

In FIG. 10, first, when the heater 2a is energized and heated in the initial state shown in FIG. 10A, the ink on the surface of the heater 2a causes film boiling, and bubbles 6 are generated. (FIG.10 (b)). This bubble 6
Rapidly expands (Fig. 10 (c)), resulting in bubbles 6
Penetrates through a part of the discharge port 5 and communicates with the outside air (FIG. 10).
(D)).

At this time, when the heater 2b is energized and heated, the ink on the surface of the heater 2b causes film boiling to generate bubbles 6
a is generated (FIG. 10 (e)). The bubble 6a generated by the heater 2b is generated in the vicinity of the end portion of the ink soul 7 that protrudes in front of the ejection port 5 due to the expansion of the bubble 6, so that the ink soul 7 can be separated by the bubble 6a. .. This allows the ink drop 7 to be an independent drop.
It is possible to more quickly form a and fly it, and it is possible to perform stable ejection with an improved ejection speed. Further, since the bubbles 6a are generated in this portion, the ejected ink droplets and the ink in the ink path do not adhere and remain in this portion, and the volume of the ejected ink droplets 7a becomes more uniform. It is possible to prevent the bubbles 6 from being enclosed by the residual ink. As a result, it is possible to perform stable ejection in which the volume of ejected ink droplets is always constant.

The void portion (FIG. 10 (f)) generated near the ejection port 5 due to the ejection of the ink droplet 7a is filled with new ink (FIG. 10 (g)), and the state before ejection (FIG. 10 (g)) is obtained. 10
Return to (a)).

In the above discharge process, FIG. 10 (d) shows the state at the moment when the bubbles communicate with the outside air. At this time, in order to prevent the gas in the bubbles from being blown out from the discharge port 5, For example, the above conditions (1) to (3) may be satisfied. This is a condition in which the bubbles communicate with the outside air under the condition that the internal pressure of the bubbles is lower than the outside pressure. This can prevent ink mist and splash.

As described above, the heater 2b can fly as an independent droplet more quickly and efficiently when the bubble 6 generated by the heater 2a communicates with the outside air at the ejection port 5 and the ink droplet 7 is ejected. In order to prevent the ink droplets 7 and the like from adhering to the substrate 4, that is, the upper wall of the ink passage 12 and remaining at this portion, the residual ink prevents the bubbles from closing the ejection port. It is provided. For this reason, it is preferable that the heater 2b is provided in the vicinity of the discharge port 5, that is, closer to the discharge port 5 than the heater 2a. Further, the size of the heater 2b may be set smaller than that of the heater 2a.

FIG. 11 is a waveform diagram of drive pulses for the heaters 2a and 2b for explaining the drive timing of the heater 2b.

The preferable foaming timing of the bubble 6a by the heater 2b is to start the foaming 0.2 to 2 .mu.sec after the bubble 6 communicates with the outside air in the specific embodiment shown below. This time is set to a fraction of the time required to form a complete ejected ink droplet (separate into an independent droplet) when the heater 2b is not provided. This will be described with reference to the drive pulse shown in FIG. For example, it is assumed that both heaters 2a and 2b start foaming 1.5 μsec after the start of heating, and that the bubbles caused by the heater 2a communicate with each other 1 μsec after the initiation of foaming. When the bubbling is started, as apparent from the figure, the heater 2b is driven with a delay of 2 μsec from the heater 2a. Of course, these values are determined according to the size and position of each heater and the ink properties.

Specific examples of the above-described ink jet recording method of the present invention will be described below.

Example 1 A recording head as shown in FIG. 9 was manufactured.

In this recording head, the heater 2a has a width of 28 μm, an ink path direction length of 25 μm, and a heater 2b.
Has a width of 28 μm and a flow path length of 10 μm, and is arranged so that the distance from the discharge port 5 to the tip of the heater 2a is 25 μm and the distance from the discharge port 5 to the tip of the heater 2b is 5 μm. On the other hand, the size of the ink path 12 in which the heater 2a and the heater 2b are provided and the ejection port 5 is formed at one end thereof is 25 μm in height, 36 μm in width, and 300 μm in length.
m, and the ink path 12 is set to 360 per inch.
It was provided at a book density.

C. I. Food black 2 3.0% by weight, diethylene glycol 15.0
% By weight, N-methyl-2-pyrrolidone 5.0% by weight,
Each compounding component consisting of 77.0% by weight of ion-exchanged water was stirred in a container to uniformly mix and dissolve, and then the pore size was 0.4.
Ink having a viscosity of 2.0 cps (20 ° C.) obtained by filtering with a 5 μm polyfluoroethylene fiber filter was supplied to the liquid chamber 10 from an ink supply port (not shown), and ejection was attempted.

At this time, the driving conditions for the heaters 2a and 2b are that the applied voltage is 5.5 V and the pulse width is 5 μm.
In this example, the driving start timing of the heater 2b is 3 μsec from the driving start timing of the heater 2a.
Delayed

Under this condition, image signals were applied to the 16 heaters 2a and 2b so as to form a checkered pattern for each pixel, and ink was ejected and adhered to the recording paper. As a result, there was no density unevenness on the recording paper. The desired checkered pattern was drawn. When this image was magnified and observed, it was a clear image without excess ink scattering and background stains.

When the discharge speed of the ink droplet was measured using a pulse light source and a microscope, it was about 12 m / sec.

(Comparative Example) In the recording head of Example 1, when ink droplets were ejected without heating the heater 2b, the ejection speed of the ink droplets was about 9 m / s.

FIG. 12 is a schematic perspective view showing a main part of an ink jet recording apparatus capable of recording according to the first embodiment.

In FIG. 12, the recording head 101 has 48 ink ejection ports (not shown) on the surface facing the recording paper 107 in the conveying direction of the recording paper 107. Also,
The recording head 101 is provided with an ink path (not shown) communicating with each of the 48 ejection ports, and the recording head 101 is configured so as to correspond to each ink path.
Heaters that generate thermal energy for ejecting ink are formed on one substrate. As described above, these heaters generate heat by the electric pulse applied to the recording data according to the recording data, whereby a boiling film is generated in the ink, and the bubbles are generated by the boiling film. Ink is ejected. Each ink path is provided with a common liquid chamber that communicates with them in common, and the ink stored therein is supplied to the ink path according to the ejection operation in each ink path.

The carriage 102 carries the recording head 101, and slidably engages with a pair of guide rails 103 extending parallel to the recording surface of the recording paper 107. As a result, the recording head 101 can move along the guide rail 103, and along with this movement, recording is performed by ejecting ink toward the recording surface at a predetermined timing. After the above movement, the recording paper 107 is conveyed by a predetermined amount in the direction of the arrow in the drawing, and the above movement is performed again to perform recording. By repeating such an operation, the recording paper 10
In 7, we will record sequentially.

The above-mentioned conveyance of the recording paper 107 is carried out by a pair of conveying rollers 1 arranged above and below the recording surface.
This is done by rotating 04 and 105. Further, a platen 106 for maintaining the flatness of the recording surface is arranged on the back side of the recording surface of the recording paper 107.

The above-mentioned movement of the carriage 102 is made possible by driving, for example, a belt (not shown) attached to the carriage 102 by the motor, and the transport rollers 104 and 105 are also rotated by the motor. It becomes possible by being transmitted to.

FIG. 13 is a block diagram showing the control arrangement of the ink jet recording apparatus shown in FIG.

In FIG. 13, a CPU 200 executes control processing of each part operation of the apparatus and data processing. ROM
The processing procedure and the like are stored in the 200A, and the driving pulse data of each of the heaters 2a and 2b as described in FIG. 11 is stored. The RAM 200B is used as a work area for executing the above processing.

Ink ejection from the recording head 101 is
The CPU 200 supplies print data and drive control signals for driving the heater to the head driver 101A. Further, the CPU 200 has a carriage motor 220 for moving the carriage 102.
The rotation of the paper feed (PF) motor 50 for rotating the feed rollers 104 and 105 is controlled via motor drivers 220A and 50A, respectively.

In carrying out the present invention, the bubble communicating and discharging method, which is one of the features of the present invention, that is,
In the process of generating bubbles for ink ejection, a method in which the bubbles communicate with the outside air at the ejection port is used, but the conditions described in the above-mentioned “Background Art” are preferable for further carrying out the present invention. 1 to 3 and the condition that the ink path is not blocked until the bubble communicates with the outside air in the generation process (the ink lump protruding from the ejection port due to the generation of the bubble is continuous with the ink in the ink path). Is desirable.

In addition to the electrothermal converter (heater) shown in the above embodiment, for example, laser light can be used as the heat energy generating means for generating bubbles.

(Others) The present invention can be effectively applied to a full line type recording head having a length corresponding to the maximum width of a recording medium which can be recorded by the recording apparatus.
Such a recording head may have a configuration that satisfies the length by a combination of a plurality of recording heads or a configuration as one recording head integrally formed.

In addition, even in the case of the serial type shown in FIG. 12, the recording head fixed to the apparatus main body or the electrical connection with the apparatus main body or the ink from the apparatus main body by being attached to the apparatus main body. The present invention is also effective when a replaceable chip-type recording head that can be supplied or a cartridge-type recording head in which an ink tank is integrally provided in the recording head itself is used.

Further, as the constitution of the recording apparatus of the present invention, it is preferable to add ejection recovery means of the recording head, preliminary auxiliary means and the like because the effects of the present invention can be further stabilized. Specifically, heating is performed by using a capping means, a cleaning means, a pressure or suction means for the recording head, an electrothermal converter or a heating element other than this, or a combination thereof. Examples thereof include a preliminary heating unit for performing the discharge and a preliminary discharge unit for performing discharge different from the recording.

Regarding the type and number of recording heads to be mounted, for example, only one is provided corresponding to a single color ink, and a plurality of inks having different recording colors and densities are supported. A plurality of pieces may be provided. That is, for example, the recording mode of the recording apparatus is not limited to the recording mode of only the mainstream color such as black, but may be either integrally formed of the recording heads or a combination of a plurality of them. The present invention is also very effective for an apparatus provided with at least one of full-color recording modes by color mixing.

In addition, as the form of the ink jet recording apparatus of the present invention, besides the one used as an image output terminal of an information processing apparatus such as a computer, a copying apparatus combined with a reader or the like, and a facsimile apparatus having a transmission / reception function are provided. It may be in a form or the like.

[0081]

As is apparent from the above description, the first heat energy generating means generates the first heat energy in the ink.
Bubbles grow, and in the process of ejecting ink by this growth, the bubbles communicate with the outside air. Then, the ink in the ejection process in which the bubbles are communicated is separated by the second bubbles generated by the second thermal energy generating means, and ejected ink droplets are formed. As a result, the speed of the ejected ink droplets is improved and stabilized, and the ink that adheres to and remains on the ink path wall can be eliminated. Ink splash and mist can be suppressed to prevent background stains on the image and stains inside the apparatus when the apparatus is used, and recording with stable ejection amount and stable landing accuracy can be performed.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a recording head for explaining a conventional example of an ink ejection method.

FIG. 2 is a schematic cross-sectional view of a recording head for explaining another conventional example of an ink ejection method.

FIG. 3 is a schematic cross-sectional view of a recording head for explaining still another conventional example of an ink ejection method.

FIG. 4 is a schematic cross-sectional view of a recording head for explaining still another conventional example of an ink ejection method.

5A and 5B are cross-sectional views of a main part of the recording head for explaining a suitable recording head to which the present invention is applied and a discharge method thereof.

FIG. 6 is a diagram showing changes in bubble internal pressure and bubble volume according to the ejection method of the present invention.

FIG. 7 is a diagram showing changes in the bubble internal pressure, bubble volume, and bubble expansion rate according to the discharge method of the present invention.

FIG. 8 is a diagram showing changes in bubble internal pressure, bubble volume, and bubble expansion rate according to the ejection method of the present invention.

9A and 9B are an exploded perspective view and a schematic cross-sectional view, respectively, of a recording head according to an embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view of a recording head for explaining the inkjet recording method of the present invention.

FIG. 11 is a drive pulse waveform diagram for explaining heater driving according to the inkjet recording method of the present invention.

FIG. 12 is a schematic perspective view of an ink jet recording apparatus capable of implementing each of the embodiments of the present invention.

13 is a block diagram showing an example of a control configuration of the device shown in FIG.

[Explanation of symbols]

 1 Substrate 2a, 2b Heater 4 Top plate 5 Discharge port 6 Bubble 7a Ink droplet 8 Partition wall 10 Liquid chamber 12 Ink path 101 Recording head 200 CPU 200A ROM 200B RAM

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Okuma 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masanori Takenouchi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon (72) Inventor Masashi Miyagawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akira 3-30-3 Shimomaruko, Ota-ku, Tokyo Canon Inc. ( 72) Inventor Kazuhiro Nakajima 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Nao Yaegashi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (10)

[Claims] 1. An ink jet recording method using a recording head comprising an ejection port for ejecting ink, and an ink path communicating with the ejection port, wherein thermal energy is applied to a predetermined portion of the ink path. Generating a first bubble in the ink, and ejecting the ink from the ejection port based on the generation of the first bubble, and communicating the first bubble with the outside air at the ejection port. In the ink passage, thermal energy is applied from the predetermined portion of the ink passage to the ejection port side, so that the second bubble is applied to the ink after the first air bubble is communicated with the outside air.
And a step of generating bubbles. 2. The ink jet recording method according to claim 1, wherein the ink path is not blocked by the bubbles during the communication. 3. The ink jet recording method according to claim 1, wherein during the communication, the bubbles are communicated with the outside air under the condition that the internal pressure of the bubbles is equal to or lower than the outside atmospheric pressure. 4. The bubble is communicated with the outside air under the condition that the acceleration of the moving speed of the tip portion of the bubble in the discharge direction is not positive at the time of the communication. Inkjet recording method. 5. The distance La between the discharge port side end of the thermal energy action portion and the bubble discharge port side end is equal to the end of the action portion opposite to the discharge port side and the bubble discharge. 5. The bubble is communicated with the outside air at the discharge port under the condition of La / Lb ≧ 1 with respect to the distance Lb to the end portion on the side opposite to the outlet side. The ink jet recording method according to claim 2. 6. An ejection port for ejecting ink, an ink path communicating with the ejection port, and an ink path provided in the ink path for applying thermal energy to the ink to generate bubbles in the ink. A first thermal energy generating unit, and a first thermal energy generating unit provided on the ejection port side by the first thermal energy generating unit for applying thermal energy to the ink to generate bubbles in the ink. And a second thermal energy generating means, wherein the first thermal energy generating means communicates the air bubbles with the outside air in the process of ejecting ink from the ejection port by the air bubbles generated by the action of the heat energy. And the second thermal energy generating means is used to generate bubbles in the ink after the communication by the action of the thermal energy. An ink jet recording head, characterized in that it is. 7. The ink passage is formed by opposing walls, and the second thermal energy generating element is provided on a wall of the ink passage opposite to the wall on which the first thermal energy generating element is provided. The ink jet recording head according to claim 6, wherein 8. An ink jet recording apparatus for recording on a recording medium by ejecting ink, an ejection port for ejecting ink, an ink path communicating with the ejection port, and an ink path provided in the ink path. A first thermal energy generating means for applying thermal energy to the ink to generate bubbles in the ink; and a first thermal energy generating means provided in the ink passage on the ejection port side. A recording head comprising: a second thermal energy generating means for applying thermal energy to the ink to generate bubbles in the ink; and a heat generating mechanism for driving the first thermal energy generating means to generate heat. First driving means for communicating the bubble with the outside air in the process of ejecting ink from the ejection port by the bubble generated by the action of energy; An ink jet recording apparatus, comprising: a second driving unit for driving a second thermal energy generating unit and generating bubbles in the ink after the communication by the action of the generated thermal energy. .. 9. The ink path is formed by walls facing each other, and the second thermal energy generating element is provided on a wall of the ink path facing the wall on which the first thermal energy generating element is provided. The inkjet recording apparatus according to claim 8, wherein the inkjet recording apparatus is an inkjet recording apparatus. 10. An ink jet recording apparatus for forming bubbles due to film boiling by generating thermal energy, and communicating the bubbles to the outside air to eject ink droplets from an ejection port, the action being performed in the vicinity of the ejection port. An ink jet recording apparatus comprising: a separating unit that rapidly changes the physical properties of the ink ejected from the ink path and the ink in the ink path.