JPH10114085A - Ink-jet recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To do a sure recovery action and to make ink discharge constant by a method in which after the discharge opening of a recording head being closed by a cap means, ink is sent by a pump means, the pressure of the inside is made constant, the cap means is opened/closed and separated from the discharge opening, and ink is sent by a low pressure. SOLUTION: A cap opening/closing frame 32 is driven by a recovery action command, the discharge opening of a recording head 1 is blocked by a cap 4, an air release valve 16 is closed, and a pump 18 is driven to make a high pressure in the recording head 1. When a subtank 30 detects ink-full by a sensor 36, during a set time, high pressure force is applied to the recording head 1 and the subtank 30. Next, the pump 18 is stopped, the valve 16 is opened, rubbing is done, and the discharge opening is kept being blocked by the cap 4 for a set time. After that, after the cap 4 being brought back by the frame 32, the valve 16 is closed, the pump 18 is driven, and a low pressure is applied to the recording head 1 and the subtank 30 for a set time.

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 which has an ink jet recording head and forms an image by ejecting ink onto a recording medium in accordance with recording data, and a high density printing apparatus equipped with the ink jet recording head. The present invention relates to an ink jet recording apparatus capable of recording an image.

[0002]

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

An ink jet recording apparatus has excellent features such as quietness during recording, high-speed printing, and high image quality.

[0004] However, when air bubbles enter the print head, a print trouble occurs such that the ink is not normally ejected. When the recording failure occurs, high image quality, which is one of the features, is impaired.

[0005] Further, the recording failure is also caused by thickening of the ink near the discharge port, adhesion of paper powder by a recording medium near the discharge port, and adhesion of other foreign matter.

When the recording failure occurs, the image formation must be stopped halfway and a recovery operation must be performed to restore the recording failure to normal. As described above, since the recovery operation stops the image formation halfway, high-speed printing, which is one of the features, is impaired.

It is sufficient that the recovery operation is performed once to reliably recover the image. However, if the recovery fails, the recovery operation must be performed again. Then, the time required for the recovery becomes unnecessary, and the high-speed printability is further impaired. In addition, there is a disadvantage that a useless recording medium is consumed due to the failure of the recovery. Therefore, it is necessary to surely restore the recording failure to normal by one recovery operation.

A method of recovering from the above-mentioned recording failure in a conventional ink jet recording apparatus is disclosed in JP-A-60-1985.
As described in JP-A-13556, there is a method of pressurizing an air layer of an ink supply container by a pressure pump. In this configuration, 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 the recovery operation, there is JP-A-3-184872. This ink jet recording apparatus includes a circulating supply unit having an ink pressurizing pump and a valve. The apparatus further comprises means for detecting a state of the ink jet recording apparatus, and controls operation timings of the ink pressurizing pump and the valve according to the state. Further, at the time of the circulation operation by the circulation supply means, the ink is discharged from the ejection port to remove foreign matter. In addition, foreign matter such as ink fixed in the vicinity of the ejection port after being left for a long period of time is dissolved by immersing the liquid in the liquid absorbed by the liquid absorber disposed in the capping means.

[0010] It is stated that by doing so, an 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 to a level necessary to recover from a recording failure. . Until the required pressure is further reached, the ink gradually flows out of the ejection port performing normal printing. Therefore, a large amount of unnecessary ink is consumed by the recovery operation.

In the method of controlling the operation timing of the ink pressurizing pump and the valve by detecting the state of the ink jet recording apparatus, since the image is recovered only by discharging the ink from the discharge port as described above, the method is considerably difficult. Unnecessary ink is consumed for the recovery operation, leading to a reduction in running cost.

As described above, if unnecessary ink is consumed in the recovery operation, the ink in the ink supply container is wasted. In this case, the ink to be used for forming an image, which is the original purpose of the ink jet recording apparatus, is wasted.

In the case of dissolving the fixed ink adhering in the vicinity of the discharge port by immersing it in a liquid, there is no problem if the ink is excellent in re-dissolvability, but it takes a considerable time to dissolve the ink which is difficult to re-dissolve. Resulting in. Then, the time required for the recovery operation becomes redundant.

If the ink supply system is configured as disclosed in JP-A-60-13556 and JP-A-3-184872, the former pressurizes the air layer of the ink supply container with a pressure pump. The time required to increase the pressure required for the recovery operation varies. In the latter case, the pressing force is greatly changed due to the variation of the flow path resistance of the supply system. Therefore, it is difficult for both of them to control the amount of ink discharged from the discharge port in a small range.

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

Incidentally, recently, in order to further enhance the above-described high printability, the density and size of the recording head have been accelerated. Therefore, the recording head must form a clearer image by discharging a small amount of ink from the discharge port. As one of the means, there is a method in which a solvent such as a surfactant is added to the ink used in the ink jet recording apparatus so as to increase the permeability to the recording medium.

However, since the surfactant is very easily foamed, if the surfactant is added to the ink, the ink itself becomes very easily foamed.

Therefore, in the above-mentioned recovery operation, it is necessary to reliably recover an image even with such an easily foamed ink. The present invention has been made in view of these problems, and it is an object of the present invention to pressurize ink to a recording head and increase the pressure to a required pressure in a state in which 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 desired amount of ink discharge, and controlling the amount of ink discharged from the discharge port, the amount of ink consumption related to the recovery operation can be managed, and the normal image formation is always performed. It is an object of the present invention to provide an ink jet recording apparatus capable of maintaining a state in which printing is possible.

[0020]

According to the present invention, there is provided an ink jet recording apparatus comprising: a recording head; an ink supply container; an ink supply means; a pump means for pumping ink from the ink supply container to the recording head; A step of closing the discharge port of the recording head by the cap means, and a step of closing the discharge port of the recording head by the pump means after closing the discharge port. Pressure-feeding to the recording head, a cap means opening and closing step of opening and closing the cap means for a set time after the inside of the recording head has a constant pressure state, and after closing the cap means, Returning the internal pressure to a normal state, separating the cap unit and the discharge port, and stopping the pump unit for a set time. Thereafter, a step of pressure-feeding the ink into the head with the pressure of the pump means lower than the pressure feed by the pump means after closing the discharge port is performed. Comprising a temperature detection means for detecting, the low-pressure pumping time varies depending on the detection result of the temperature detection means,
The low-pressure pumping time is longer when the environmental temperature is higher than when the environmental temperature is lower, and discharges ink from the discharge ports during the step of sealing the discharge ports of the print head with the cap means, During the step of closing the ejection port, the frequency at which ink is ejected is a frequency equal to or less than half of the maximum response frequency of the recording head, and after the step of opening the ejection port by the cap unit, ink is ejected from the ejection port. After the step of discharging and opening the discharge port, the discharge of the ink from the discharge port is performed at least twice or more, and after the discharge port is sealed, the ink of the ink supply container is In the step of pressure-feeding the recording medium to the recording head, the drive signal is input to the pressure generating means, and the pressure of the pumping means is reduced to a low pressure, and the pressure is reduced into the head. In the step of pressure feeding, a drive signal that does not lead to ink ejection from the ejection port is input to the pressure generation means, and in the cap means opening / closing step of opening the cap means for a set time, according to the detection result of the temperature detection means 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 according to the detection result of the temperature detecting means, and the pump means after closing the discharge port, In the step of pressure-feeding the ink in the ink supply container to the recording head, the pressure-feeding is performed at least twice or more, and the pressure of the pump means is reduced to a low pressure to pump the ink into the head. The pumping is performed at least twice or more, and the pump is closed by closing the discharge port. The ink of the ink supply container when the step of pumping to the recording head,
It is characterized in that it is determined whether or not the ink in the ink supply container is ink-end.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows an embodiment of the present invention. In the figure, reference numeral 1 denotes a recording head provided with a plurality of ejection ports for ejecting ink. Further, in the recording head 1, pressure generating means is disposed to face each of the plurality of ejection ports. An electromechanical transducer or the like can be used for the pressure generating means. The recording head 1 is connected to a recording head driving circuit (not shown), and performs the ink ejection by inputting a driving signal from the recording head driving circuit to the recording head 1.

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

The recording head 1 and the ink pack 11 installed in the ink supply container 10 are communicated by an ink flow path 13. The ink pack 11 is arranged so that the 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 an ink flow path 14. Sub tank 30
Is provided with a sensor 36, and is configured to detect ink full when the sub tank 30 is filled with ink 40. As the sensor 30, a photosensor, an interrupter, or the like can be used.

An air vent 37 is provided in the sub tank 30.
Is provided. Air 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 pressurization at a high pressure described later.

Further, the ink supply container 10 is provided with an atmosphere opening port 17 so that the air supply valve 16 can be easily opened and closed to the atmosphere. An electromagnetic valve or the like whose opening and closing control is easy can be used as the atmosphere release valve 16.

The atmosphere opening valve 16 performs an opening / closing operation in accordance with 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. As the pump 18, a diaphragm type air pump or the like can be used.

A thermistor 39 is attached to the recording head 1 and has a structure for detecting an environmental temperature.

Here, the ink supply means will be described.

In 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 discharge port with the consumption of the ink by the ink discharge.

The ink 40 in the sub tank 30 decreases due to the ink ejection. As the ink 40 decreases, the sensor 41 detects ink low. Then, the air release valve 16 is closed, and a low pressure is applied by the pump 18, and the ink 15 in the ink pack 11 is pumped to the sub tank 30. The above-mentioned sensor 3 is supplied by the pressure feeding by the low pressure pressurization.
When 6 detects that the ink is full, the pump 18 stops applying the low pressure and opens the atmosphere release valve 16. Then, the ink 40 in the sub tank 30 discharges ink and the ink pack 1
It gradually decreases with the flow to 1. Then, the sensor 41 detects ink low again.

In this manner, as long as the ink 15 is present in the ink pack 11, the ink 15 necessary for forming an image is always pumped from the ink pack 11 into the sub-tank 30, and the ink 40 is filled. .

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. In this area, a cap unit and a waste ink collecting unit are provided.

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 a cap 4
The pump pressure is switched between a high pressure and a low pressure by a pressure switching mechanism (not shown) connected to the pump. In this embodiment, the pressure is high when the discharge port is closed by the cap 4, and the pressure is low when the discharge port is open to the atmosphere.

The cap 4 has a JIS hardness of 40-60.
It is desirable to use a soft elastic body of a certain degree. In this embodiment, a silicone rubber having a hardness of 45 degrees is used. Also, chloroprene rubber or the like can be used as the material of the cap 4.

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

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 opens and closes the cap 4 with respect to the discharge port of the recording head 1. (FIG. 2A,
(B)). Normally, during image formation or standby, FIG.
In the state (a), the cap 4 is spaced from the recording head 1.

The cap swing lever 34 is also rotatable about the fulcrum 0 (arrow F in the figure) by a drive source and a transmission mechanism (not shown). Rocks. The cap fixing body 31 to which the cap 4 and the wiper 5 are fixed is moved by the operation of the cap swing lever 34 so that the groove 33
The ejection port surface of the recording head 1 is moved up and down along
(B), (c)).

The recording head 1 mounted on the carriage 2 with the ejection opening closed by the cap 4 described above.
A rubbing operation (symbol S109 to be described later) for opening and closing the discharge port to the atmosphere is performed by repeating the operation (moving on the guide shaft 3 in the front and back direction on the paper surface of FIG. 2).

Next, the waste ink collecting means will be described. In the figure, reference numeral 20 denotes a waste ink container,
Is installed below the recovery operation area. Scraper 2
Numeral 2 is provided for wiping ink adhered to the cap 4 or the wiper 5. The absorbing material 21a is for absorbing and holding the ink wiped off 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 to close the ejection port of the recording head 1 with the cap 4 (S101). At this time, the moving speed of the cap 4 is desirably set to 1.0 to 2.0 mm / sec so as not to break a meniscus formed in a discharge port described later.

In 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 × E5 to 0.3 ×
It is desirable to be E5Pa.

Within the set time T1 of the timer S104 (30 seconds in this embodiment), the sub-tank 30
When the above-described ink-full state is detected, the timer S1
High pressure is applied to the recording head 1 and the sub tank 30 during the set time of 06.

At this time, the sensor 36 detects
When the full state is not detected, the operation of the pump 18 is stopped (S201), the air release valve 16 is opened (S202), and the state in which the discharge port is closed by the cap 4 for the set time of the timer S203 is maintained. 32 is driven to separate the cap 4 from the discharge port. At this time, since the sensor 36 has not detected the ink full state as described above, the ink amount required 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 a display panel provided in the ink jet recording apparatus of the present invention (not shown).

After the above-described timer S106, the pump 18 is stopped (S107), and the air release valve 16 is opened (S10).
8) The rubbing operation (S1)
09). The operation speed at the time of performing the rubbing operation S109 is desirably 5 to 10 mm / sec in order to ensure the removability of the fixed ink and foreign matter attached to the ejection surface described later.

The discharge port is closed with the cap 4 for the set time of the timer S111, and thereafter, the cap opening / closing frame 32 is driven to perform a wiping operation of opening the discharge port from the cap 4 (S112). The ink adhering to the ejection port surface is wiped off by the wiper 5. further,
The ink adhered to the cap 4 and the wiper 5 is scraped off by the scraper 22 of the waste ink container 20, and is absorbed by the absorbent 21a. The surface of the cap 4 is an absorbent 21
b and is cleaned.

Next, the cap opening / closing frame 32 is driven to retract the cap 4 to the state shown in FIG.
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 desirably 1.0 to 2.0 mm / sec in order not to break a meniscus of a discharge port described later.

Thereafter, the state is maintained for the set time of the timer S113, and then the atmosphere release valve 16 is closed (S11).
4) The pump 18 is driven (low pressure) (S115),
A low pressure is applied to the recording head 1 and the sub tank 30 for a set time of the timer S116. At this time, since the discharge port is open to the atmosphere, if the pressure of the pump 18 is applied too high, ink will come out from the discharge port and consume unnecessary ink. In order to prevent this, the low pressure by the pump 18 is + 0.02 × E5 to 0.04 × 10E5Pa with respect to the atmospheric pressure.
It is desirable that Thereafter, the pump 18 is stopped (S
117), the atmosphere release valve 16 is opened (S118), and the recovery operation ends (S119).

FIG. 4 shows the pressure applied to the ink in the flow path (pressure P in the flow path) and the flow rate of the ink in the flow path (pressure P in the flow path) as time elapses (time t) when the above-described recovery operation is performed. It is a graph showing ink flow velocity V). (A) is the pump pressure,
(B) shows the ink flow velocity. In the drawing, (+) of the ink flow rate 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.

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

In the sequence A shown in FIG.
In the area after the ink full is detected by 6, the ink does not flow into the flow path. In this region, the inside of the flow path is maintained 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.

In sequence B, since the atmosphere release valve 16 is open to the atmosphere as described above, the pressure gradually returns to the atmospheric pressure. At this time, the ink flow rate flows from the sub tank 30 to the ink tank 11.

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

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 at the ink end. Also, 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 maintained long.

Also, as described above, bubbles mixed into the flow path in the recording head 1 due to the high pressure are applied to the sub tank 30.
To form an air layer 38. Timer S10
The air in the air layer 38 is discharged to the atmosphere from the air vent 37 in order to perform the high-pressure pressurization for 6 set times.

Further, as described above, the rubbing operation S109
As a result, the discharge port alternately opens and shuts off to the atmosphere. 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, so that the ink is ejected from the ejection port. The discharge amount of the ink 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 increased to the high pressure of the pump 18 by the set time of the timer S106. Therefore, the ink discharge amount can always be constant.

At the time of this rubbing operation, the cap 4
And the discharge port surface are in contact with each other.
And are rubbed.

As described above, during the rubbing operation, the ink is discharged from the discharge port, and at the same time, the surface of the discharge port is rubbed. Will be eliminated promptly. Further, since the number N1 of rubbing operations can be changed by the number S110, not only the above-described ink discharge amount can be easily changed, but also the removability of fixed ink and foreign matter can be easily changed.

Needless to say, the elimination of ink and foreign matter stuck to the ejection port surface is facilitated by the discharge of ink from the ejection port.

Further, by performing the wiping operation in S112, the fixed ink and foreign matter around the discharge port are wiped out, and a normal and stable image can be formed.

As described above, the sub-tank 30 is arranged to be higher than the ink pack 11 with respect to the horizontal plane. The set time of the timer S113 is 5 to 20
By setting sec, the ink 40 in the sub tank 30 gradually flows into the ink pack 11. At this time, air bubbles that could not be completely discharged by the above-described high pressure due to the ink flow, for example, air bubbles that had stagnated at the stagnation point of the flow path in the recording head 1 (a place where the ink hardly flowed) were formed together with the ink in the flow path. Is flowed.

Thereafter, the ink and the bubbles are caused to flow by the pump 18 at a low flow rate due to the above-described low pressure pressurization, so that the bubbles can flow into the sub tank 30 without stagnation at the stagnation point of the flow path. Can be.

By performing the low-pressure pressurization after the high-pressure pressurization, even if the ink has a large amount of dissolved gas in the ink (for example, 20 ppm or more), the bubbles in the flow path can be reliably removed from the sub-tank 30. Can flow into.

As described above, by performing further pressurization at a lower pressure after pressurization at a higher pressure, a more reliable recovery operation can be performed.

Also, even with the above-mentioned ink which is easily foamed, the main air bubbles flow into the sub-tank 30 by pressurization with high pressure, and the fine air bubbles generated by foaming generated by pressurization with high pressure are applied by low pressure. Sub tank 3 by pressure
Flowed into 0.

Accordingly, a reliable recovery operation can be performed even for ink that is easily foamed.

The bubbling of the ink becomes more remarkable when the ambient temperature is higher. This is because as the environmental temperature increases, the viscosity of the ink decreases and the surface tension of the ink decreases.

Therefore, in FIG. 3, the set time of the timer S116 is set in advance according to the temperature detected by the thermistor 39. The setting time of the timer S116 is set longer when the environmental temperature is high than when it is low. That is, the pressurizing time of the low pressure by the pump 18 is lengthened. By doing so, the bubbles generated by the bubbling by the high-pressure pressurization can reliably flow into the sub-tank 30 even in the case of high bubbling.

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

As described above, by changing the set time of the timer S116 depending on the environmental temperature, a reliable recovery operation can be performed regardless of the environmental temperature.

As described above, when the environmental temperature increases, the viscosity of the ink decreases. In other words, the lower the environmental temperature, the higher the viscosity of the ink.

Therefore, in FIG. 3, the rubbing operation S1 is performed.
09, the number of times N1 (S110) is designated,
It is set in advance in accordance with the temperature detected by the thermistor 39.

For example, when the environmental temperature is 10 to 20 ° C., the number N1
5 times, ambient temperature 21 to 30 ° C. 3 times, environmental temperature 31
1 to 40 ° C. is performed once. In this way, even if the viscosity of the ink changes due to a change in the environmental temperature, the ink attached to the ejection port surface can be reliably removed.

The operation speed in the above-described rubbing operation S109 is set in advance according to the difference in the environmental temperature. Then, even when the number of times N1 is changed according to the environmental temperature, the amount of ink discharged from the ejection port in the rubbing operation S109 can be controlled. The operating speed is reduced when the ink discharge amount is desired to be increased, and is increased when the ink discharge amount is desired to be reduced. That is, the amount of ink consumed in the recovery operation can be controlled according to the environmental temperature. In addition, the removal of the ink attached to the ejection port surface can be reliably performed by changing the operation speed of the rubbing operation S109 and changing the number S110 of the rubbing operations S109.

Further, by setting the operation speed of the rubbing operation S109 and the number of times N1 (S110) in accordance with the viscosity of the ink used in the ink jet recording apparatus of the present invention, an 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 inside of the ejection port to cause a recording failure in which a normal image cannot be formed.

However, in the present invention, as shown in the embodiment of FIG. 3, during the operation S101 of closing the ejection port of the recording head 1 with the cap 4, the moving speed of the cap 4 is set to 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 opening is closed by the cap 4, unnecessary recording trouble does not occur.

Further, by discharging ink from the discharge ports of the recording head 1 (hereinafter referred to as flushing operation) in the operation S101 of closing the discharge ports of the recording head 1 with the cap 4, the following effects are exhibited.

In 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 aforementioned cap 4
Thus, it is possible to further suppress the occurrence of unnecessary recording failure at the time of the operation S101 of closing the ejection port of the recording head 1.

It is desirable that the frequency of the ink ejection for performing the flushing operation be less than half the limit frequency (maximum response frequency) at which ink can be ejected from the recording head 1 (1 kHz in this embodiment). . By doing so, the ink ejection from the ejection port of the recording head 1 is more stable, and the ink consumption due to the flushing operation can be reduced.

In the ink jet recording apparatus according to the present invention, the flow path of the recording head 1 is internally divided for each color, and the color flow can be easily achieved by providing the flow path for each color.

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

When colorization is performed and a plurality of colors of ink are used, the ink discharged from the discharge port in the above-described rubbing operation S109 is mixed to generate mixed color ink. 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 attached mixed color ink enters the ejection openings, the formation of an image after the recovery operation is not 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 discharge ink. It is desirable that the frequency of this ink ejection be less than half the frequency of the above-described recording head 1 (2 kHz in this embodiment).

In the state shown in FIG. 2A after the wiping operation S112 as described above, the ink 40 flows from the sub tank 30 to the ink pack 11. Therefore, the mixed color ink that has entered through the ejection port tends to flow into the ink pack 11.

As described above, in the state shown in FIG. 2A, the flushing operation is immediately performed at a frequency equal to or less than half of the maximum response frequency, so that the ink can be stably ejected. 1 can be discharged to the outside. That is, even when colorization is performed, an image of a normal color can always be formed.

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

In FIG. 4, a drive signal is input from the recording head 1 to the recording head 1 during pressurization by high pressure until the detection of ink full in the sequence A. By doing so, air existing in the flow path of the recording head 1
In addition, 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.

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

Also, by inputting a drive signal to the recording head 1 that does not lead to ink ejection from the ejection port at the time of low-pressure pressurization in the sequence C of FIG. 4, the above-described high-pressure pressurization is performed. By oscillating bubbles in the flow path of the recording head 1 generated by the bubbling, the bubbles can flow to the sub tank 30 more quickly.

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

FIG. 5 is a graph similar to FIG. 4 when the above-described high-pressure pressurization and low-pressure pressurization are performed separately in the recovery operation. As in FIG. 4, (a) shows the pump pressure,
(B) shows the ink flow velocity. In the drawing, (+) of the ink flow rate 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. Note that the sequence E in the figure performs the same sequence as the sequence B in FIG.

In the sequence D in the figure, the above-described high-pressure pressurization is divided into two times. S100 to S106 are performed in the flowchart of FIG. 3, thereafter, 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.

In this manner, a large amount of ink flow in the flow path can be generated by one recovery operation, so that more air and air bubbles in the flow path can be quickly and efficiently removed from the sub tank 30. Can flow to Therefore, a more efficient recovery operation can be performed.

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

In this way, the air bubbles stagnating in the flow path can be swung by the ink flow and flow more quickly through the sub-tank 30. That is, an efficient recovery operation can be performed more reliably by one recovery operation.

[0099] High-pressure pressurization and low-pressure pressurization are separately performed. Further, in the present embodiment, the number of divisions has been described twice, but it is apparent 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. However, it is needless to say that the present invention can also be applied to an ink supply system in which ink is placed on a carriage.

[0101]

As described above, in the present invention, the recording head, the ink supply container, the ink supply means, the pump means for pumping the ink from the ink supply container to the recording head, A step of sealing the discharge port of the recording head with the cap means, and the step of closing the discharge port with the pump means to seal the ink in the ink supply container with the pump means. 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 reaches a constant pressure state, and a step of reducing the internal pressure of the recording head after closing the cap means. Returning to a normal state; separating the cap unit from the discharge port; stopping the pump unit for a set time; Performing a recovery operation including a step of reducing the pressure of the pump unit to a lower pressure than that of the pump unit after closing the mouth and forcing the ink into the head, thereby mixing the ink into the flow path in the recording head. 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 reliably increased to the high pressure of the pump. Therefore, the ink discharge amount can always be constant.

The bubbles in the discharge port are discharged to the atmosphere together with the ink, and the ink, foreign matter, etc. fixed on the discharge port surface are quickly eliminated. In addition to being able to easily change the amount of discharged ink, it is also possible to easily change the removability of fixed ink and foreign matter.

In addition, air bubbles that have stagnated at a stagnation point (a place where ink hardly flows) in the flow path in the recording head can be reliably discharged from the flow path.

Further, even if the amount of dissolved gas in the ink is large, it is possible to perform a reliable recovery operation in which bubbles in the flow path can be reliably removed.

Further, even if the ink is easily foamed, a reliable recovery operation can be performed.

The ink jet recording apparatus is provided with a temperature detecting means for detecting an environmental temperature, and a reliable recovery operation can be performed irrespective of the environmental temperature because the low-pressure pumping time differs depending on the detection result of the temperature detecting means.

By setting the low pressure pumping time longer when the ambient temperature is high than when it is low, the time required for the recovery operation can be shortened when the environmental temperature is low, and the environmental temperature at which foaming becomes a problem can be reduced. , The recovery operation can be reliably performed.

In the step of closing the ejection port of the recording head by the cap means, ink is ejected from the ejection port to suppress the occurrence of unnecessary recording failure due to breaking the meniscus formed in the ejection port. be able to.

In the step of closing the ejection port of the recording head, the frequency at which ink is ejected is less than half the maximum response frequency of the recording head, so that ink ejection can be performed stably. Unnecessary recording failures due to are not generated.

After the step of opening the discharge port by the cap means, ink is discharged from the discharge port,
Since the mixed-color ink can be quickly discharged to the outside of the recording head 1, a normal color image can always be formed even when colorization is performed.

By performing the discharge of the ink from the discharge port at least twice or more after the step of opening the discharge port, the occurrence of unnecessary recording trouble can be further suppressed.

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

Further, since the time for pressurization by the pump can be set short, a more efficient recovery operation can be performed.

In the step of pumping the ink into the head by setting the pressure of the pump means to a low pressure, a drive signal which does not lead to the ink being ejected from the ejection port is input to the pressure generating means, so that bubbling is caused. The generated air bubbles in the flow path can flow more quickly, and more optimal recovery operation can be performed.

In the cap opening / closing step in which the cap is opened for the set time, the number of times the set time is opened according to the detection result of the temperature detection means is different, so that even if the viscosity of the ink is different, the ink adhering to the ejection port surface can be reduced. It can be reliably 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, 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 from each other, so that the ink adhered to the ejection port surface can be more reliably eliminated. Can be.

Further, an optimum recovery operation can be performed irrespective 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 divided into at least two or more times, so that it is even more possible. Air in the flow path of
In addition, the bubbles can flow quickly and efficiently, and a more efficient recovery operation can be performed.

In the step of pumping the ink into the head by setting the pressure of the pump means to a low pressure, the pumping is performed at least twice or more, and the pump means is used after the discharge port is sealed. By performing the pressure feeding at least twice or more, the bubbles can flow quickly and efficiently. Therefore, an efficient recovery operation can be performed.

In the step of pumping the ink in the ink supply container to the recording head by the pump means after closing the discharge port, it is determined whether or not the ink in the ink supply container is ink-end. Thus, it can be easily detected that the ink pack is at the ink end.
In addition, 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 maintained long. it can.

[Brief description of the drawings]

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

FIG. 2 is a cap operation diagram for explaining the operation of the cap in the above device.

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

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

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Recording head 4 Cap 5 Wiper 10 Ink supply container 11 Ink pack 12, 38 Air layer 15, 40 Ink 16 Atmospheric release valve 18 Pump 20 Waste ink container 21a, 21b Absorbent material 22 Scraper 30 Subtank 32 Cap opening / closing frame 36, 41 Sensor 37 air vent 39 thermistor

Claims (14)

[Claims] 1. A pressure change generated by inputting a drive signal to a pressure generating means is given 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 ink jet recording apparatus to be formed, a recording head for discharging ink, an ink supply container for storing ink to be supplied to the recording head, an ink supply unit for supplying a flow path for supplying ink to the recording head, and the ink Pump means for pressure-feeding ink from a supply container to the recording head, and cap means for closely contacting the ejection port of the recording head and closing the ejection port, wherein the cap means seals the ejection port of the recording head; Pumping the ink in the ink supply container to the recording head by the pump means after closing the discharge port; A step of opening and closing the cap means for a set time after the inside of the head becomes a constant pressure state; a step of returning the internal pressure of the recording head to a normal state after closing the cap means; A step of separating the means and the discharge port, and stopping the pump means for a set time, and then lowering the pressure of the pump means to a lower pressure than the pumping by the pump means after sealing the discharge port, and into the head. An ink jet recording apparatus performing a recovery operation including a step of pumping ink. 2. The ink jet recording apparatus according to claim 1, wherein said ink jet recording apparatus includes a temperature detecting means for detecting an environmental temperature, and said low-pressure pumping time varies depending on a detection result of said temperature detecting means. 3. The ink jet recording apparatus according to claim 2, wherein the low pressure pumping time is longer when the ambient temperature is high than when it is low. 4. The ink jet recording apparatus according to claim 1, wherein the ink is ejected from the ejection port during the step of sealing the ejection port of the recording head 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 openings of the recording head is less than half the maximum response frequency of the recording head. . 6. The ink jet recording apparatus according to claim 1, wherein after the step of opening the ejection port by the cap means, ink is ejected from the ejection port. 7. The ink jet recording apparatus according to claim 6, wherein after the step of opening the ejection port, the ink ejection from the ejection port is performed at least twice. 8. The method according to claim 1, wherein the drive signal is input to the pressure generating means in the step of pumping the ink in the ink supply container to the recording head by the pump means after closing the discharge port. 1. An ink jet recording apparatus. 9. The method according to claim 9, wherein in the step of pumping the ink into the head by setting the pressure of the pump means to a low pressure, a drive signal which does not lead to the ink being ejected from the ejection port is input to the pressure generating means. The ink jet recording apparatus according to claim 1, wherein 10. The ink jet recording apparatus according to claim 1, wherein in the cap opening / closing step of opening the cap for a set time, the number of times the set time is opened differs depending on a detection result of the temperature detecting means. 11. The ink jet recording apparatus according to claim 1, wherein in the cap opening / closing step of opening the cap for a set time, an operation speed for opening the set time varies depending on a detection result of the temperature detecting means. 12. The method according to claim 12, wherein, after the discharge port is sealed, the pumping is performed at least twice in the step of pumping the ink in the ink supply container to the recording head by the pump unit. Item 7. An ink jet recording apparatus according to Item 1. 13. The ink-jet recording apparatus according to claim 1, wherein the pumping in the step of pumping the ink into the head by setting the pressure of the pump unit to a low pressure is performed at least twice or more. . 14. A method for determining whether or not the ink in the ink supply container is at an ink end in a step of pumping the ink in the ink supply container to the recording head by the pump means after closing the discharge port. The ink jet recording apparatus according to claim 1, wherein the recording is performed.