JP3533848B2 - Ink jet recording device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer having an ink jet recording head and ejecting ink onto a recording medium in accordance with recording data to form an image, and an ink jet recording head mounted with high density. The present invention relates to an ink jet type recording device capable of recording.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, ink is contained in an ink supply container, and the ink is ejected from an ejection port provided in a recording head to form an image.

The ink jet recording apparatus has excellent characteristics such as quietness during recording, high-speed printability, and high image quality.

However, when air bubbles enter the inside of the recording head, a recording failure occurs such that the ink cannot be ejected normally. When the recording failure occurs, high image quality, which is one of the characteristics, is impaired.

Further, the recording trouble is also caused by thickening of ink in the vicinity of the ejection port, adhesion of paper powder by the recording medium in the vicinity of the ejection port, and adhesion of other foreign matter.

When the recording failure occurs, it is necessary to stop the image formation on the way and perform a recovery operation for restoring the recording failure to the normal state. As described above, the recovery operation stops the image formation on the way, so that the high-speed printability, which is one of the characteristics, is impaired.

It is sufficient that the recovery operation is performed once to surely recover the image, but if the recovery fails, the recovery operation must be performed again. Then, it takes unnecessary time for recovery, further impairing the high-speed printability. Further, the failure of the recovery causes a problem that a wasteful recording medium is consumed. Therefore, it is necessary to surely restore the recording failure to the normal state by one recovery operation.

As a method for recovering from the recording failure in the conventional ink jet recording apparatus, Japanese Patent Laid-Open No. Sho 60-
As in Japanese Patent No. 13556, there is a method of pressurizing an air layer of an ink supply container with a pressurizing pump. This is configured such that a high pressure is generated in the ink supplied to the recording head, the thickened ink flows out from the ejection port, and the image is restored.

As another method of recovery operation, there is Japanese Patent Laid-Open No. 3-184872. This inkjet recording apparatus is provided with a circulation supply means having an ink pressurizing pump and a valve. Further, the ink jet recording apparatus is provided with means for detecting the state thereof, and the operation timings of the ink pressurizing pump and the valve are controlled according to the state. Further, during the circulation operation by the circulation supply means, the ink is discharged from the ejection port to remove the foreign matter. Further, foreign matter such as ink adhered in the vicinity of the ejection port after being left for a long period of time is dissolved by being immersed in the liquid absorbed by the liquid absorber arranged in the capping means.

By doing so, it is said that the optimum recovery operation can be performed according to the state of the ink jet recording apparatus.

[0011]

However, in the method of pressurizing the air layer of the ink supply container with the pressurizing pump as described above, it takes time to increase the pressure required to recover the recording trouble. . Further, until the required pressure is reached, the ink gradually flows out from the ejection port which performs normal recording. Therefore, a large amount of unnecessary ink is consumed by the recovery operation.

Further, in the case of the method of detecting the state of the ink jet recording apparatus and controlling the operation timings of the ink pressurizing pump and the valve, as described above, the image is recovered only by discharging the ink from the ejection port, so that it is considerably Unnecessary ink is consumed for the recovery operation, leading to a reduction in running cost.

As described above, if unnecessary ink consumption is large in the recovery operation, the ink in the ink supply container is wastefully consumed. Then, the ink that should be used for forming an image, which is the original purpose of the inkjet recording apparatus, is wasted.

When the fixed ink adhering to the vicinity of the ejection port is dissolved by dissolving it in a liquid, there is no problem if the ink has excellent re-dissolvability, but it takes a considerable time to dissolve the ink that is difficult to re-dissolve. Resulting in. Then, the time required for the recovery operation becomes redundant.

Further, when the ink supply system is configured as in the above-mentioned JP-A-60-13556 and JP-A-3-184872, the former pressurizes the air layer of the ink supply container by the pressurizing pump. The time required to increase the pressure required for the recovery operation varies. Further, in the latter case, the applied pressure changes greatly due to variations in the flow path resistance of the supply system. Therefore, it is difficult for both of them to manage the discharge amount of ink from the discharge port in a small range.

Therefore, in the above-mentioned publication, it is extremely difficult to manage the ink consumption amount to be small and to discharge the air in the flow path to the outside of the flow path of the recording head.

By the way, in recent years, in order to further improve the above-mentioned high printability, the recording head has been made higher in density and smaller in size. Therefore, the recording head must form a clearer image by ejecting a small amount of ink from the ejection port. As one means of this, there is a method of adding a solvent such as a surfactant to the ink used in the ink jet recording apparatus to enhance the permeability of the ink into the ink.

However, since the above-mentioned surface-active agent is very easy to foam, when the surface-active agent is added to the ink, the ink itself becomes very easy to foam.

Therefore, in the recovery operation, it is necessary to surely recover the image even with the ink that easily foams. The present invention has been made in view of these problems, and an object thereof is to increase the pressure up to a necessary pressure by pumping ink to a recording head in a state where the ejection port is closed by a cap that is in close contact with the ejection port. After that, by opening and closing the cap to obtain the ink discharge amount that suits the purpose and controlling the ink discharge amount from the ejection port, the ink consumption amount related to the recovery operation can be managed, and the normal image formation is always performed. An object of the present invention is to provide an ink jet recording apparatus capable of maintaining a state where

[0020]

An ink jet recording apparatus according to the present invention comprises a recording head, an ink supply container, an ink supply means, a pump means for pressure-feeding ink from the ink supply container to the recording head, and the recording. A step of sealing the ejection port of the recording head with the cap means, and a cap means for closely contacting the ejection port of the head and closing the ejection port; and a step of sealing the ejection port with ink of the ink supply container by the pump means. To the recording head, a step of opening and closing the cap means for opening and closing the cap means for a set time after the inside of the recording head is in a constant pressure state, and after closing the cap means, Returning the internal pressure to a normal state, separating the cap means from the discharge port, and stopping the pump means for a set time. Thereafter, a recovery operation consisting of a step of pressure-feeding the ink into the head by setting the pressure of the pump means to a lower pressure than the pressure-feeding by the pump means after sealing the ejection port, and the ink jet recording apparatus is set to the ambient temperature. The temperature detection means for detecting is provided, and the pressure feeding time of the low pressure varies depending on the detection result of the temperature detection means,
The low pressure pressure feeding time is longer when the environmental temperature is higher than when the environmental temperature is low, and ink is ejected from the ejection port when the ejection port of the recording head is sealed by the cap unit. In the step of sealing the ejection port, the frequency at which the ink is ejected is equal to or less than half of the maximum response frequency of the recording head, and the ink is ejected from the ejection port after the step of opening the ejection port by the cap means. After the step of ejecting and opening the ejection port, the ejection of the ink from the ejection port is performed at least twice in a divided manner, and after the ejection port is sealed, the ink of the ink supply container is closed by the pump means. In the step of pressure-feeding the recording head to the recording head, the drive signal is input to the pressure generating means, and the pressure of the pump means is set to a low pressure and In the step of pressure-feeding, the drive signal that does not cause ink to be ejected from the ejection port is input to the pressure generating means, and in the cap means opening / closing step that opens the cap means for a set time, depending on the detection result of the temperature detecting means, In the opening / closing process of the cap means for opening the cap means for the set time, the operation speed for opening the set time is different depending on the detection result of the temperature detecting means, and the pump means is used after sealing the discharge port. In the step of pressure-feeding the ink of the ink supply container to the recording head, the pressure-feeding is performed at least twice in a step of lowering the pressure of the pump means to pressure-feed the ink into the head. The pumping is performed at least twice in a divided manner, and after the discharge port is closed, the pump means is used. The ink of the ink supply container when the step of pumping to the recording head,
It is characterized in that it is judged whether the ink in the ink supply container is ink-end.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The details of the present invention will be described below based on illustrated embodiments.

FIG. 1 shows an embodiment of the present invention. Reference numeral 1 in the drawing is a recording head, which is provided with a plurality of ejection ports for ejecting ink. Further, a pressure generating means is arranged inside the recording head 1 so as to face each of the plurality of ejection ports described above. An electromechanical conversion element or the like can be used as the pressure generating means. The printhead 1 is connected to a printhead drive circuit (not shown), and the ink is ejected by inputting a drive signal to the printhead 1 from the printhead drive circuit.

The recording head 1 is mounted on the carriage 2,
An image is formed on a recording medium by selectively ejecting the ink while moving on the guide shaft 3.

The recording head 1 and the ink pack 11 installed in the ink supply container 10 are connected by an ink flow path 13. The ink pack 11 is arranged so that its height in the horizontal direction is lower than that of the recording head 1 and a sub tank 30 described later.

A sub-tank 30 is connected to the recording head 1 via the ink flow path 14. Sub tank 30
Is provided with a sensor 36, and has a structure for detecting ink-full when the sub-tank 30 is filled with the ink 40. A photo sensor, an interrupter, or the like can be used as the sensor 30.

Further, the sub tank 30 has an air vent 37.
Is provided. The bubbles existing in the ink 40 in the sub tank 30 form an air layer 38 over time.
The air in the air layer 38 is gradually discharged to the atmosphere when the above-described ink-full detection state is maintained by the high-pressure pressurization described later.

Further, the ink supply container 10 is provided with an atmosphere opening port 17 so that the atmosphere opening valve 16 can easily open and close to the atmosphere. As the atmosphere release valve 16, a solenoid valve or the like whose opening / closing control is easy can be used.

The atmosphere opening valve 16 is opened and closed according to a recovery operation described later. A pump 18 is connected to the air layer 12 in the ink supply container 10 via an air flow path 19. A diaphragm type air pump or the like can be used as the pump 18.

A thermistor 39 is mounted on the recording head 1 to detect the environmental temperature.

Here, the ink supply means will be described.

At the time of forming an image, the ink 40 in the sub tank 30 is supplied through the ink flow path 14 by the capillary force of the ejection port as the ink is consumed by the ink ejection.

The ink 40 in the sub tank 30 is reduced by the ink ejection. When the ink 40 decreases, the sensor 41 detects ink low. Then, the atmosphere release valve 16 is closed and a low pressure is applied by the pump 18 to pump the ink 15 in the ink pack 11 to the sub tank 30. The above-mentioned sensor 3 is provided by pressure feeding by the low pressure pressurization.
When 6 detects ink full, the pump 18 stops the pressurization at the low pressure and opens the atmosphere release valve 16. Then, the ink 40 in the sub tank 30 is ejected and the ink pack 1
The flow to 1 gradually decreases. Then, the sensor 41 detects the ink low again.

In this way, as long as the ink 15 is contained in the ink pack 11, the ink 15 necessary for forming an image is constantly pressure-fed from the ink pack 11 into the sub-tank 30 and is filled with the ink 40. .

Further, FIG. 1 shows a configuration in a non-image forming area. This area is a standby position of the recording head 1 and is an area where the recovery operation of the recording head 1 is performed. Cap means and waste ink recovery means are installed in this area.

Next, the structure and operation of the cap means will be described. FIG. 2 is an explanatory view showing the operation of the cap means. The cap 4 is in close contact with the ejection port of the recording head 1 and closes the ejection port. In addition, the pump 18 is the cap 4
The pump pressure is switched between high pressure and low pressure by a pressure switching mechanism (not shown) connected to the. In this embodiment, the pressure is high when the discharge port is closed by the cap 4, and low when the discharge port is open to the atmosphere.

The cap 4 has JIS hardness of 40-60.
A soft elastic body is desirable. This embodiment uses silicon rubber having a hardness of 45 degrees. Chloroprene rubber or the like can be used as the material of the cap 4.

The wiper 5 is a member for wiping off the ink adhering to the ejection port surface of the recording head 1. Cap 4
The wiper 5 is fixed to the cap fixing body 31, and is further installed on the cap opening / closing frame 32. At this time, the cap 4 and the wiper 5 may be integrated.

The cap opening / closing frame 32 is configured to be rotatable about a fulcrum 0 (arrow E in the figure) by a drive source and a transmission mechanism (not shown), and the cap 4 is opened / closed with respect to the ejection port of the recording head 1. (Fig. 2 (a),
(B)). Normally, the image shown in FIG.
In the state of (a), the cap 4 is spaced from the recording head 1.

The cap swing lever 34 is also configured to be rotatable about the fulcrum 0 (arrow F in the figure) by a drive source and a transmission mechanism (not shown), and the cap fixing body 31 is connected via the connecting lever 35. Rock. The cap fixing body 31 that fixes the cap 4 and the wiper 5 is moved by the operation of the cap swing lever 34, so that the groove 33 of the cap opening / closing frame 32.
The ejection port surface of the recording head 1 is moved up and down (see FIG. 2).
(B), (c)).

Further, the recording head 1 mounted on the carriage 2 in a state where the ejection port is closed by the cap 4 described above.
Is repeated to move the guide shaft 3 (front and back direction in FIG. 2) to perform a rubbing operation (S109 to be described later) for opening and closing the discharge port to the atmosphere.

Next, the waste ink collecting means will be described. Reference numeral 20 in the drawing denotes a waste ink container, and the recording head 1
It is installed below the recovery operation area. Scraper 2
2 is provided for wiping off the ink adhering to the cap 4 or the wiper 5. The absorbing material 21a is for absorbing and holding the ink wiped by the scraper 22, and the absorbing material 21b is used for cleaning the cap 4.

FIG. 3 is a flowchart showing a sequence relating to the recovery operation of the recording head 1. Step S10
When the recovery operation command is issued at 0, the cap opening / closing frame 32 is driven, and the ejection port of the recording head 1 is closed by the cap 4 (S101). At this time, the moving speed of the cap 4 is preferably 1.0 to 2.0 mm / sec so as not to damage the meniscus formed in the ejection port described later.

At step S102, the atmosphere release valve 16 is closed to seal the inside of the ink supply container. Next, the pump 18 is driven (high pressure) to increase the pressure inside the recording head 1 (S103).
High pressure is +0.15 x E5 to 0.3 x relative to atmospheric pressure
E5 Pa is desirable.

Within the set time T1 of the timer S104 (30 sec in this embodiment), the sub tank 30 detects the sensor 36.
When the above-mentioned ink full is detected by the timer S1
A high pressure is applied to the recording head 1 and the sub tank 30 during the set time of 06.

At this time, the above-mentioned ink is detected by the sensor 36.
When the full is not detected, the drive of the pump 18 is stopped (S201), the atmosphere opening valve 16 is opened (S202), the state in which the discharge port is blocked by the cap 4 for the set time of the timer S203 is maintained, and then the cap opening / closing frame. 32 is driven to separate the cap 4 from the discharge port. At this time, as described above, since the sensor 36 does not detect the ink full, the ink amount necessary for forming the image in the ink pack 11 is insufficient, that is, the ink end (S205). At this time, the ink-end is displayed to the user by the display panel provided in the inkjet recording apparatus of the present invention (not shown).

After the above-mentioned timer S106, the pump 18 is stopped (S107) and the atmosphere release valve 16 is opened (S10).
8), the rubbing operation for the number N1 of times S110 (S1
09) is performed. It is desirable that the operation speed when performing the rubbing operation S109 is 5 to 10 mm / sec in order to ensure the removability of the fixed ink and the foreign matter adhering to the ejection surface described later.

The state in which the discharge port is blocked by the cap 4 is maintained for the set time of the timer S111, and then the cap opening / closing frame 32 is driven to perform the wiping operation of opening the discharge port from the cap 4 (S112). The ink attached to the ejection port surface is wiped off by the wiper 5. further,
The ink attached to the cap 4 and the wiper 5 is scraped off by the scraper 22 of the waste ink container 20 and absorbed by the absorbing material 21a. The surface of the cap 4 is the absorbent material 21.
It is rubbed on b and cleaned.

Then, the cap opening / closing frame 32 is driven to retract the cap 4 to the state shown in FIG. 2A (S1).
15) The cap 4 and the discharge port are separated from each other.
At this time, the speed at which the cap opening / closing frame 32 is slid downward is preferably set to 1.0 to 2.0 mm / sec so as not to damage the meniscus of the ejection port described later.

After that, the state is held for the set time of the timer S113, and then the atmosphere release valve 16 is closed (S11
4), drive the pump 18 (low pressure) (S115),
A low pressure for the set time of the timer S116 is applied to the recording head 1 and the sub tank 30. At this time, since the ejection port is open to the atmosphere, if the pressure of the pump 18 is too high, the ink will be ejected from the ejection port and unnecessary ink will be consumed. To prevent this, the low pressure by the pump 18 is + 0.02 × E5 to 0.04 × 10E5 Pa with respect to the atmospheric pressure.
Is desirable. Then, the pump 18 is stopped (S
117), the atmosphere opening valve 16 is opened (S118), and the recovery operation is finished (S119).

FIG. 4 shows the pressure applied to the ink in the flow channel (pressure in the flow channel) and the flow velocity of the ink in the flow channel (time t) when the above-described recovery operation is performed. 6 is a graph showing an ink flow velocity V). (A) is the pump pressure,
(B) shows the ink flow velocity. In the figure, (+) of the ink flow velocity indicates the ink flow from the ink tank 11 to the sub tank 30, and (−) indicates the ink flow from the sub tank 30 to the ink tank 11.

The sequence A in the figure is S100 to S108 in the flowchart of FIG. 3, and the sequence B is S109 to S1.
13, sequence C corresponds to S114 to S119, respectively.

In sequence A in the figure, the sensor 3 of FIG.
The ink does not flow into the flow path in the area after the ink-full state is detected by 6. In this region, the inside of the flow path is kept at a high pressure. Due to this high pressure, the air in the air layer 38 in the sub tank 30 is discharged from the air vent 37.

Further, in the sequence B, since the atmosphere opening valve 16 is opened to the atmosphere as described above, the atmospheric pressure is gradually returned to the atmospheric pressure. At this time, the ink flow velocity is flowing from the sub tank 30 to the ink tank 11.

In Sequence C, low pressure is applied to the flow path. As described above, the ink pack 11 includes the sub tank 30.
In the sequence B, the ink 40 in the sub-tank 30 gradually flows into the ink pack 11 because it is arranged at a lower position. Therefore, due to the low pressure in the sequence C, the sub-tank 30 is again supplied.

Next, the recovery operation of this embodiment will be described with reference to the flowchart of FIG.

As described above, by providing the set time T1 with the timer S104, it can be easily detected that the ink pack 11 is the ink end. Also, the timer S
Since the time is set at 104, the high pressure is not applied more than necessary. As a result, unnecessary pressure is not applied to the recording head 1 due to high pressure, so that there is no fear of damaging the recording head 1 and the life of the recording head 1 can be kept long.

Further, as described above, the bubbles mixed in the flow path in the recording head 1 due to the high pressure pressurization are sub tanks 30.
It is fluidized in and forms an air layer 38. Timer S10
Since high pressure is applied for the set time of 6, the air in the air layer 38 is discharged to the atmosphere from the air vent 37.

The rubbing operation S109 is performed as described above.
The discharge port opens and shuts off against the atmosphere alternately. When the ejection port is opened to the atmosphere, the inside of the recording head 1 is at a high pressure due to the high pressure applied by the pump 18, and thus the ink is ejected from the ejection port. The amount of ink discharged at this time can be easily changed by changing the speed of the operation of moving on the guide shaft 3 described above. Further, the pressure in the recording head 1 can be reliably made high by the set time of the timer S106. Therefore, a constant ink discharge amount can be obtained.

Also, during this rubbing operation, the cap 4
Since the discharge port surface is in contact with the discharge port surface, cap 4
Are rubbed with.

In this way, during the rubbing operation, the ink is ejected from the ejection port, and at the same time, the ejection port surface is rubbed, so that the air bubbles inside the ejection port are ejected to the atmosphere together with the ink, and the ink, foreign matter, etc. fixed to the ejection port surface Promptly eliminated. Further, since the number N1 of rubbing operations can be changed by the number of times S110, it is possible to easily change the above-described ink discharge amount and easily change the removability of fixed ink and foreign matter.

Needless to say, the removal of the ink and foreign matter adhered to the ejection port surface is facilitated by the above-described ink ejection from the ejection port.

Further, by performing the wiping operation of S112, the fixed ink and foreign matters around the ejection port can be swept away, and a normal and stable image can be formed.

As described above, the sub-tank 30 is arranged so that its height with respect to the horizontal plane is higher than that of the ink pack 11. Set the time of timer S113 to 5 to 20
By setting to sec, the ink 40 in the sub tank 30 gradually flows into the ink pack 11. At this time, bubbles that could not be exhausted due to the above-described high-pressure pressurization due to the ink flow, for example, bubbles that were stagnant at the stagnation point of the flow path in the recording head 1 (a place where the ink is difficult to flow), together with the ink flow path Flowed to.

After that, the ink and the bubbles are caused to flow by the pump 18 at a slow flow rate due to the pressurization at the low pressure, so that the bubbles can be surely flowed into the sub-tank 30 without being stagnant at the stagnation point of the flow path. You can

By applying the low pressure after the high pressure, even in the case of the ink having a large amount of dissolved gas in the ink (for example, 20 ppm or more), the bubbles in the flow path can be surely generated. Can flow in.

As described above, a more reliable recovery operation can be performed by applying a lower pressure after the high pressure.

Further, even in the case of the ink that easily foams as described above, the main bubbles flow into the sub-tank 30 by pressurization by high pressure, and the fine bubbles generated by foaming generated by pressurization by high pressure are applied by low pressure. Sub tank 3 by pressure
Flowed into 0.

Therefore, a reliable recovery operation can be performed even with ink that easily foams.

The higher the ambient temperature is, the more remarkable the foaming property of the ink becomes. This is because when the environmental temperature rises, the viscosity of the ink lowers and the surface tension of the ink lowers.

Therefore, in FIG. 3, the set time of the timer S116 is preset according to the temperature detected by the thermistor 39. When the environmental temperature is high, the set time of the timer S116 is set longer than when the environmental temperature is low. That is, the low pressure pressurization time by the pump 18 is lengthened. By doing so, it is possible to reliably flow the bubbles generated by the foaming by the above-described high-pressure pressurization into the sub tank 30 even when the foaming property is high.

On the other hand, when the environmental temperature is low, the bubbling property of the ink does not matter so much, so that the time required for the recovery operation can be shortened by shortening the setting time of S116.

By changing the set time of the timer S116 according to the ambient temperature in this way, a reliable recovery operation can be performed regardless of the ambient temperature.

Further, as described above, the viscosity of the ink decreases as the ambient temperature rises. In other words, the lower the ambient temperature, the higher the ink viscosity.

Therefore, in FIG. 3, the rubbing operation S1 is performed.
The number of times N1 (S110) in which the number of times 09 is specified is
The temperature is preset according to the temperature detected by the thermistor 39.

For example, when the ambient temperature is 10 to 20 ° C., the number of times is N1.
5 times, environmental temperature 21 to 30 ° C 3 times, environmental temperature 31
It is once at 40 to 40 ° C. By doing so, even if the viscosity of the ink is different due to the change of the environmental temperature, the ink attached to the ejection port surface can be reliably removed.

Further, the operation speed in the rubbing operation S109 is set in advance depending on the difference in environmental temperature. Then, even when the number N1 is changed depending on the environmental temperature, the amount of ink discharged from the ejection port in the rubbing operation S109 can be controlled. When it is desired to increase the ink discharge amount, the operation speed is slowed, and when it is desired to decrease the ink discharge amount, the operation speed is increased. That is, the ink consumption amount in the recovery operation can be controlled according to the environmental temperature. Further, the removal of the ink adhering to the ejection port surface can be surely performed by changing the operation speed of the rubbing operation S109 and changing the number of times S110 of the rubbing operation S109.

By setting the operation speed and the number of times N1 (S110) of the rubbing operation S109 according to the viscosity of the ink used in the ink jet recording apparatus of the present invention, the optimum recovery operation can be performed regardless of the viscosity of the ink. .

A meniscus of ink is formed at the ejection port of the recording head 1. When a strong impact is applied to the meniscus, the meniscus is broken, and air enters the ejection port, which causes a recording failure in which a normal image cannot be formed.

However, in the present invention, during the operation S101 of closing the ejection port of the recording head 1 with the cap 4 as shown in the embodiment of FIG. 3, the moving speed of the cap 4 is 1.0 to 2 as described above. It is performed at 0.0 mm / sec. Therefore, the ejection port can be reliably closed by the cap 4 with almost no impact on the meniscus. That is, when the ejection port is closed by the cap 4, an unnecessary recording failure does not occur.

Further, in the operation S101 of closing the ejection port of the recording head 1 with the cap 4, ink is ejected from the ejection port of the recording head 1 (hereinafter, flushing operation), so that the following effects are exhibited.

During the flushing operation, since the ink is always ejected stably from the ejection port, the meniscus is not broken even if a slight impact is applied. Therefore, the above-mentioned cap 4
Thus, it is possible to further suppress the occurrence of an unnecessary recording failure during the operation S101 of closing the ejection port of the recording head 1.

Further, it is desirable that the frequency of ink ejection for performing this flushing operation is a frequency not more than half of the limit frequency (maximum response frequency) at which ink ejection of the recording head 1 can be performed (1 kHz in this embodiment). . By doing so, the ink ejection from the ejection port of the recording head 1 becomes more stable, and the ink consumption due to the flushing operation can be reduced.

In the ink jet recording apparatus of the present invention, the flow path of the recording head 1 is internally divided for each color, and the structure for the flow path is provided for each color, whereby colorization can be easily performed.

When colorization is performed, M (magenta),
A problem is color mixing in which C (cyan), Y (yellow), and K (black) inks are mixed. When color mixing occurs, a normal color image cannot be formed.

When colorization is performed and inks of a plurality of colors are used, the inks discharged from the ejection ports in the rubbing operation S109 are mixed to generate mixed color inks. Most of the mixed color ink is removed by the subsequent wiping operation S112, but a part of the mixed color ink may adhere to the vicinity of the ejection port. If the adhered mixed color ink enters the ejection port, the image formation after the recovery operation will not be performed in a normal color.

However, in the flowchart of FIG. 3, the wiping operation S for opening the discharge port from the cap 4 is performed.
In the state of FIG. 2A after 112, the flushing operation is immediately performed to eject ink. It is desirable that the frequency of this ink ejection be less than half the frequency of the recording head 1 described above (2 kHz in this embodiment).

As described above, in the state of FIG. 2A after the wiping operation S112, the ink 40 is flowing from the sub tank 30 to the ink pack 11. Therefore, the mixed color ink that has entered from the ejection port tends to flow into the ink pack 11.

As described above, in the state of FIG. 2 (a), the flushing operation is performed immediately at a frequency equal to or less than half of the maximum response frequency, so that ink ejection can be stably performed, and the mixed color ink is promptly printed. 1 can be discharged to the outside. That is, even when colorization is performed, it is possible to always form an image of a normal color.

Further, the ink ejection of the flushing operation is performed at least twice in a divided manner (in this embodiment, the divided time interval is about 0.2 to 0.5 sec).
By doing so, a stable meniscus in which ink is not ejected can be obtained during the division. Therefore, it is possible to form an image of a normal color even when the color is formed more stably.

Further, in FIG. 4, a drive signal is input from the recording head 1 to the recording head 1 during the pressurization by the high pressure until the ink full in the sequence A is detected. By doing so, the air existing in the flow path of the recording head 1,
Also, the bubbles are swung, and the bubbles easily flow into the sub tank 30 more quickly. Therefore, a more optimal recovery operation can be performed.

Further, the set time S10 of high pressure pressurization in FIG.
6 can be set short, and more efficient recovery operation can be performed.

Further, by inputting a drive signal to the recording head 1 which does not cause ink to be ejected from the ejection port at the time of low pressure pressurization in the sequence C of FIG. 4, the above high pressure pressurization is performed. By swinging the bubbles in the flow path of the recording head 1 generated by bubbling, the bubbles can be flowed to the sub tank 30 more quickly.

Therefore, a more optimal recovery operation can be performed. Further, the set time S116 of pressurization of low pressure in FIG. 3 can be set short, and more efficient recovery operation can be performed.

FIG. 5 is a graph similar to that of FIG. 4 when the above-mentioned high pressure pressurization and low pressure pressurization in the recovery operation are performed separately. As in FIG. 4, (a) is the pump pressure,
(B) shows the ink flow velocity. In the figure, (+) of the ink flow velocity indicates the ink flow from the ink tank 11 to the sub tank 30, and (−) indicates the ink flow from the sub tank 30 to the ink tank 11. The sequence E in the figure is the same as the sequence B in FIG.

In the sequence D in the figure, the above-mentioned high-pressure pressurization is performed twice. This can be easily performed by performing S100 to S106 in the flowchart of FIG. 3, then opening the atmosphere opening valve 16, maintaining the state for a set time, and closing the atmosphere opening valve 16 again after the set time has elapsed.

By doing so, a large amount of ink flow in the flow path can be generated by one recovery operation, so that more air and bubbles in the flow path can be quickly and efficiently produced. Can flow to. Therefore, a more efficient recovery operation can be performed.

Further, in the sequence E in the figure, the above-mentioned low pressure pressurization is divided into two times. In the flow chart of FIG. 3, after performing S116, the atmosphere release valve 16 is opened, the state is maintained for a set time, and after the set time elapses, the atmosphere release valve 16 is closed again, which can be easily performed.

By doing so, the air bubbles stagnant in the flow path can be swung by the ink flow and quickly flowed by the sub tank 30. That is, the recovery operation can be performed more reliably and efficiently with one recovery operation.

The high pressure pressurization and the low pressure pressurization are separately performed. Further, in the present embodiment, the number of divisions for each two times has been described, but it is clear that the same effect can be obtained even if the number of divisions is further increased.

In this embodiment, an ink circulation type ink supply system having a sub tank has been described as an example, but it goes without saying that an ink supply system of a type in which ink is placed on a carriage is also applicable.

[0101]

As described above, in the present invention, the recording head, the ink supply container, the ink supply means, the pump means for pressure-feeding the ink from the ink supply container to the recording head, and the recording head A step of sealing the ejection port of the recording head with the cap device, and a step of sealing the ejection port of the recording head with the cap device; A step of pressure-feeding to the recording head, a step of opening and closing the cap means for opening and closing the cap means for a set time after the inside of the recording head is in a constant pressure state, and an internal pressure of the recording head after the cap means is closed. A step of returning to a normal state, a step of separating the cap means from the discharge port, a step of stopping the pump means for a set time, and then a discharge of the discharge means. The ink is mixed in the flow path in the recording head by performing a recovery operation including a step of pressure-feeding the ink into the head with the pressure of the pump means being lower than the pressure-feeding by the pump means after closing the mouth. The bubbles are discharged to the atmosphere, and the amount of ink discharged by the recovery operation can be easily changed. Further, the pressure in the recording head can be surely made high by the pump. Therefore, a constant ink discharge amount can be obtained.

Bubbles in the discharge port are discharged to the atmosphere together with the ink, and ink, foreign matter and the like adhered to the discharge port surface are promptly removed. In addition to easily changing the amount of discharged ink, it is also possible to easily change the removability of fixed ink and foreign matter.

Further, the bubbles that have stagnated at the stagnation point of the flow path in the recording head (where ink does not easily flow) can be reliably discharged from the flow path.

Further, even if the ink contains a large amount of dissolved gas, it is possible to reliably remove the bubbles in the flow path and perform a reliable recovery operation.

Further, a reliable recovery operation can be performed even with ink that easily foams.

The ink jet recording apparatus is provided with temperature detecting means for detecting the ambient temperature, and the pumping time of the low pressure varies depending on the detection result of the temperature detecting means, so that a reliable recovery operation can be performed regardless of the ambient temperature.

By making the low pressure pumping time longer when the environmental temperature is higher than when the environmental temperature is low, the time required for the recovery operation can be shortened when the environmental temperature is low, and the foaming property becomes a problem. It is possible to perform a reliable recovery operation even when the value is high.

In the step of sealing the ejection port of the recording head by the cap means, ink is ejected from the ejection port, thereby suppressing the occurrence of unnecessary recording failure due to the destruction of the meniscus formed in the ejection port. be able to.

In the step of sealing the ejection port of the recording head, the frequency at which the ink is ejected is equal to or lower than half the maximum response frequency of the recording head, so that the ink ejection can be performed stably, so that the recovery operation is performed. It does not cause unnecessary recording failures.

By ejecting ink from the ejection port after the step of opening the ejection port by the cap means,
Since the mixed color ink can be promptly discharged to the outside of the recording head 1, it is possible to always form an image of a normal color even when colorization is performed.

After the step of opening the ejection port, the ejection of the ink from the ejection port is performed at least twice in a divided manner, whereby it is possible to further suppress the occurrence of unnecessary recording trouble.

In the step of pressure-feeding the ink in the ink supply container to the recording head by the pump means after sealing the discharge port, the drive signal is inputted to the pressure generating means so that the air, and Since bubbles can be discharged from the flow path, a more optimal recovery operation can be performed.

Further, since the pressurizing time by the pump can be set to be short, more efficient recovery operation can be performed.

In the step of pressure-feeding the ink into the head by setting the pressure of the pump means to a low pressure, by inputting a drive signal to the pressure generating means that does not cause the ink to be ejected from the ejection port, bubbles are generated. The generated air bubbles in the flow path can flow more quickly, and an optimal recovery operation can be performed.

In the cap opening / closing step for opening the cap means for the set time, the number of times the set time is opened varies depending on the detection result of the temperature detecting means. It can be surely eliminated.

In the cap means opening / closing step of opening the cap means for the set time, the operation speed for opening the set time differs depending on the detection result of the temperature detecting means, so that the ink discharge amount in the recovery operation can be controlled regardless of the environmental temperature. .

Further, since the number of times the cap means is opened for the set time and the operation speed for opening the cap means for the set time in the cap means opening / closing step are different, it is possible to more reliably remove the ink adhering to the ejection port surface. You can

Further, the optimum recovery operation can be performed regardless of the viscosity of the ink.

In the step of pressure-feeding the ink in the ink supply container to the recording head by the pump means after closing the discharge port, the pressure-feeding is performed at least twice, so that it is possible to further increase the number of times. Air in the flow path of
In addition, the bubbles can be swiftly and efficiently flowed, and a more efficient recovery operation can be performed.

In the step of pressure-feeding the ink into the head by setting the pressure of the pump means to a low pressure, the pressure-feeding is performed at least twice in a divided manner, and the pump means is used after sealing the discharge port. By performing the pressure feeding at least twice in a divided manner, the bubbles can be swiftly and efficiently flowed. Therefore, an efficient recovery operation can be performed.

When the ink in the ink supply container is pressure-fed to the recording head by the pump means after the discharge port is closed, it is judged whether the ink in the ink supply container is the ink end. Thus, it can be easily detected that the ink pack is ink-end.
Further, since the high pressure is not applied more than necessary, an inadvertent pressure is not applied to the recording head 1, so that there is no fear of damaging the recording head 1 and the life of the recording head 1 can be kept long. it can.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an inkjet recording apparatus according to the present invention.

FIG. 2 is a cap operation diagram for explaining the operation of the cap in the same apparatus.

FIG. 3 is a flowchart showing a method of a recovery operation.

FIG. 4 is a graph showing a pressure in a flow path and a flow velocity of ink when a recovery operation is performed.

FIG. 5 is a graph showing the pressure in the flow path and the flow velocity of ink when a recovery operation is performed.

[Explanation of symbols]

1 recording head 4 cap 5 wiper 10 Ink supply container 11 ink pack 12, 38 Air layer 15, 40 ink 16 Atmosphere release valve 18 pumps 20 Waste ink container 21a, 21b absorber 22 scraper 30 sub tank 32 Cap open / close frame 36, 41 sensors 37 Air vent 39 Thermistor

Claims (14)

(57) [Claims] 1. A change in pressure generated by inputting a drive signal to a pressure generating means is applied to ink filled in a pressure chamber, and ink is discharged from a discharge port communicating with the pressure chamber to form a recording dot. In an inkjet recording apparatus to be formed, a recording head that discharges ink, an ink supply container that stores ink to be supplied to the recording head, an ink supply unit that functions as a flow path that supplies ink to the recording head, and the ink Pumping means for pressure-feeding ink from the supply container to the recording head; and cap means which is in close contact with the ejection opening of the recording head and closes the ejection opening, and a step of sealing the ejection opening of the recording head by the cap means, A step of pressure-feeding the ink in the ink supply container to the recording head by the pump means after sealing the discharge port; Opening and closing the cap means for a set time after the inside of the recording head has reached a constant pressure state; closing the cap means and then returning the internal pressure of the recording head to a normal state; A step of separating the means and the discharge port, the pump means is stopped for a set time, and then the pressure of the pump means is set to a lower pressure in the head than the pressure feeding by the pump means after sealing the discharge port. An ink jet recording apparatus, which performs a recovery operation including a step of feeding ink under pressure. 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus includes temperature detecting means for detecting an environmental temperature, and the pressure feeding time of the low pressure varies depending on a detection result of the temperature detecting means. 3. The ink jet recording apparatus according to claim 2, wherein the low pressure feeding time is longer when the environmental temperature is higher than when the environmental temperature is low. 4. The ink jet recording apparatus according to claim 1, wherein ink is ejected from the ejection port when the ejection port of the recording head is sealed by the cap unit. 5. The ink jet recording apparatus according to claim 4, wherein the frequency at which ink is ejected in the step of sealing the ejection port of the recording head is not more than half the maximum response frequency of the recording head. . 6. The ink jet recording apparatus according to claim 1, wherein ink is ejected from the ejection port after the step of opening the ejection port by the cap means. 7. The ink jet recording apparatus according to claim 6, wherein the ink ejection from the ejection port after the step of opening the ejection port is performed at least twice. 8. The drive signal is input to the pressure generating means in the step of pressure-feeding the ink in the ink supply container to the recording head by the pump means after sealing the discharge port. 1. Inkjet recording device 1. 9. A drive signal that does not cause ink to be ejected from the ejection port is input to the pressure generating means in the step of pumping ink into the head by setting the pressure of the pump means to a low pressure. The inkjet recording apparatus according to claim 1. 10. The ink jet recording apparatus according to claim 2 , wherein, in the cap means opening / closing step of opening the cap means for a set time, the number of times the set time is opened varies depending on the detection result of the temperature detecting means. 11. The ink jet recording apparatus according to claim 2 , wherein in the cap means opening / closing step of opening the cap means for a set time, an operation speed for opening the set time differs depending on a detection result of the temperature detecting means. 12. The pressure feeding in the step of pressure feeding the ink in the ink supply container to the recording head by the pump means after sealing the discharge port is performed at least twice. Item 1. The inkjet recording device according to item 1. 13. The ink jet recording apparatus according to claim 1, wherein the pressure feeding in the step of pressure feeding the ink into the head is performed at least twice in a divided manner by setting the pressure of the pump unit to a low pressure. . 14. When the ink in the ink supply container is pressure-fed to the recording head by the pump means after the discharge port is closed, it is determined whether the ink in the ink supply container is the ink end. The inkjet recording apparatus according to claim 1, wherein the inkjet recording apparatus is performed.