JP3424494B2 - 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.

Further, when a plurality of ink colors such as Y, M, C, and K (yellow, magenta, cyan, and black) are used for the ink, coloration is performed, the ejection ports responsible for ejecting each ink by the recovery operation. Other ink colors may be mixed in. When the mixing occurs, a color mixing phenomenon occurs, and it becomes impossible to form a normal color image.

Therefore, it is necessary to perform a recovery operation that surely restores a recording failure to normal without causing a color mixing phenomenon by one recovery operation.

As a method of recovering from the above-mentioned recording failure in a 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. A high pressure is generated in the ink supplied to the recording head, the thickened ink is caused to flow out from the ejection port, and the image is restored. Further, since the pump is constructed so as not to come into contact with ink, it is excellent in reliability of the pump.

As another recovery operation method, there is JP-A-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. This inkjet recording apparatus is excellent in that it performs an optimum recovery operation according to the state of the inkjet recording apparatus.

[0013]

As described above, in the method of pressurizing the air layer of the ink supply container with the pressurizing pump, 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 timing 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 performed. Unnecessary ink is consumed by the recovery operation.

If unnecessary ink is consumed in the recovery operation in this way, the ink in the ink supply container is wasted. Then, the ink that should be used for forming an image, which is the original purpose of the inkjet recording apparatus, is unnecessarily consumed.

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 unnecessarily long.

When a plurality of color inks are used for colorization as described above, the discharge of the inks causes the inks to be mixed with each other to generate a mixed color ink. If the mixed color ink adheres to the vicinity of the ejection port and mixes with the ink in the ejection port, the color mixing phenomenon occurs. Then, as described above, a normal color image cannot be formed.

When the consumption of the ink is reduced, not only the recovery operation does not restore a normal image, but also the mixed color ink is likely to remain in the vicinity of the ejection port, so that the occurrence of the mixed color phenomenon becomes more remarkable. turn into.

Further, when the ink supply system is constructed 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 with a 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 out of the flow path of the recording head.

Here, the foamability of the ink used in the ink jet recording apparatus will be described.

In recent years, in order to further enhance the above-mentioned high printability, the recording head is being 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. The surfactant is very foamy.

Therefore, when a surfactant 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 such ink that easily foams.

Therefore, the present invention has been made in view of these problems, and an object of the present invention is to send ink to a recording head under pressure while the ejection port is closed by a cap that is in close contact with the ejection port. After increasing the pressure to the appropriate pressure, open and close the cap to obtain the desired ink discharge amount,
By controlling the amount of ink discharged from the ejection port, the ink consumption related to the recovery operation can be managed, the color mixing phenomenon does not occur due to the recovery operation, and it is possible to always maintain a state in which a normal image can be formed. To provide a device.

[0025]

SUMMARY OF THE INVENTION An ink jet recording apparatus according to the present invention includes a recording head having an ejection port for ejecting ink, an ink supply container for storing ink to be supplied to the recording head, and an ink supply to the recording head. An ink supply unit that serves as a flow path, a pump unit that pressure-feeds the ink from the ink supply container to the recording head, and a cap unit that has a cap that is in close contact with the ejection port of the recording head and closes the ejection port. The step of sealing the ejection port of the recording head, the step of pumping the ink in the ink supply container to the recording head by the pump means after closing the ejection port, the step of returning the internal pressure of the recording head to a normal state, the cap means and the ejection means. The step of separating the outlet and the pump means rather than the pressure feeding by the pump means after stopping the pump means for a set time and then sealing the discharge port And performing the step of pumping ink to the head without discharging ink from the discharge port of the pressure as low pressure, a recovery operation consisting of. Also,
In such an inkjet recording apparatus, after the step of pressure-feeding the ink in the ink supply container to the recording head, after the inside of the recording head is in a constant pressure state, the cap means is repeatedly opened and closed for a set time to discharge the ink from the ejection port. However, it is characterized by further including a cap means opening / closing step of performing an operation of slidingly contacting the cap and the discharge port. Further, in the ink jet recording apparatus, a recess is formed at an upper end portion of the cap so as to be lower than an upper end of a surface which is in close contact with the ejection port of the recording head and closes the ejection port. Further, in the inkjet recording apparatus, the cap that is in close contact with and closes the ejection ports of a plurality of rows has a groove between portions that abut the ejection ports of each of the plurality of rows. Further, in the ink jet recording apparatus, the ink jet recording apparatus includes a temperature detecting means for detecting an environmental temperature, and a pressure feeding time of low pressure varies depending on a detection result of the temperature detecting means. Further, in the ink jet recording apparatus, the low pressure feeding time is longer when the environmental temperature is higher than when the environmental temperature is low. Further, in the ink jet recording apparatus, the ink is ejected from the ejection port during the step of sealing the ejection port of the recording head with the cap means. In addition, in such an inkjet recording device,
In the step of sealing the ejection port of the recording head, the frequency at which the ink is ejected is equal to or less than half the maximum response frequency of the recording head. Further, in the ink jet recording apparatus, the ink is ejected from the ejection port after the step of opening the ejection port by the cap means. Further, in the inkjet recording apparatus, it is characterized in that after the step of opening the ejection port, the ejection of the ink from the ejection port is performed at least twice. In addition, in such an inkjet recording device,
In the step of pumping the ink in the ink supply container to the recording head by the pump means after closing the ejection port, a driving signal is inputted to the pressure generating means. Also,
In such an ink jet recording apparatus, in the step of pumping the ink into the head by setting the pressure of the pump unit to a low pressure, a driving signal that does not cause the ink to be ejected from the ejection port is input to the pressure generating unit. Also,
In such an inkjet recording apparatus, the number of times of opening and closing the set time is different depending on the detection result of the temperature detection means in the cap opening and closing step of opening and closing the cap means and the ejection port for the set time. Further, in the inkjet recording apparatus, the operation speed of opening and closing the set time is different depending on the detection result of the temperature detection means in the cap opening and closing step of opening and closing the cap means and the ejection port for the set time. Further, in the ink jet recording apparatus according to the aspect, in the step of pressure-feeding the ink in the ink supply container to the recording head by the pump means after sealing the ejection port, the pressure-feeding is performed at least twice. Further, in the ink jet recording apparatus, the pressure feeding of the ink in the head is performed at a low pressure by pumping means, and the pressure feeding is performed at least twice or more. Further, in such an inkjet recording apparatus, the ink in the ink supply container is discharged during the process of pumping the ink in the ink supply container to the recording head by the pump means after sealing the ejection port.
The feature is that it is judged whether it is the end.

[0026]

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. In the figure, reference numeral 1 is a recording head, and a nozzle plate 400 having a later-described ejection port 401 for ejecting ink, which is described later, is attached thereto. A plurality of ejection openings 401 are arranged in the vertical direction, and a plurality of rows of the ejection openings 401 are arranged for each color of the ink used in this embodiment. In this embodiment, inks of a plurality of colors such as Y, M, C, K (yellow, magenta, cyan, black) are used for colorization.

A pressure generating means is arranged in the recording head 1 so as to face each of the plurality of ejection openings 401. 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 sensors 36 and 41. When the sub tank 30 is filled with the ink 40, the sensor 36 detects the ink full, and when the sub tank 30 decreases, the sensor 41 detects the ink low. A photo sensor, an interrupter, or the like can be used as the sensors 36 and 41.

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.
When the above-mentioned ink-full detection state is maintained by the pressurization of a high pressure which will be described later, the air layer 3 is gradually passed through the air vent 37.
The air in No. 8 is discharged to the atmosphere.

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 ambient temperature.

Here, the ink supply means will be described.

At the time of image formation, 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. Then, the sensor 41 detects ink low as described above. When the ink-low is detected, the atmosphere release valve 16 is closed and a low pressure is applied by the pump 18 to pressure-feed the ink 15 in the ink pack 11 to the sub-tank 30. When the sensor 36 detects ink-full due to pressure feeding by the low pressure, the pump 1
Reference numeral 8 stops the low pressure pressurization and opens the atmosphere release valve 16.
Then, the ink 40 in the sub-tank 30 gradually decreases due to ink ejection and flow to the ink pack 11. Then, the sensor 41 detects 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.

In the figure, reference numeral 4 is a cap, which is in close contact with the nozzle plate 400 of the recording head 1 and closes the ejection port 401.

Reference numeral 31 in FIG. 2 denotes a fixed body, which is the cap 4
Is fixed. Further, the fixed body 31 is installed on the cap opening / closing frame 32.

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 401 of the recording head 1. (Fig. 2
(A), (b)). Normally, the cap 4 is spaced from the recording head 1 in the state of FIG. 2A during image formation or standby.

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 to which the cap 4 is fixed moves up and down the ejection port surface of the recording head 1 along the groove 33 of the cap opening / closing frame 32 by the operation of the cap swing lever 34 (FIG. 2B,
(C)).

Further, the recording head 1 mounted on the carriage 2 with the ejection port 401 closed by the cap 4 described above.
Is moved on the guide shaft 3 (front and back direction in FIG. 2) to be repeated. By performing the above operation, the discharge port 401 is opened and shut off to the atmosphere, and a rubbing operation (symbol S109 described later) is performed.

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
Reference numeral 2 is provided to wipe off an ink lump 410 described later attached to the cap 4. The absorbing material 21a is for absorbing and holding the ink lump 410 wiped by the scraper 22, and the absorbing material 21b is used for cleaning the cap 4.

The pump 18 described above is constructed so that the pump pressure is switched between high pressure and low pressure by a pressure switching mechanism (not shown) connected to the cap 4. In this embodiment, the pressure is high when the discharge port 401 is closed by the cap 4, and is low when the discharge port 401 is opened to the atmosphere.

FIG. 3A is an explanatory view showing one embodiment of the cap 4.

The cap 4 is in close contact with the nozzle plate 400 of the recording head 1 and closes the ejection port 401. The cap 4 has convex portions 184 to 188 that come into contact with the ejection openings 401 of the recording head 1 arranged in a plurality of rows.

In this embodiment, the convex portions 184, 185 are K (black), and the convex portions 186, 187, 188 are C, respectively.
It is formed so as to come into contact with the ejection ports 401 that eject the respective inks of (cyan), M (magenta), and Y (yellow).

The concave portion 1 is provided between the convex portions 184 to 188.
90 to 193 are formed. Furthermore, the convex portions 184-18
As described above, the concave portions 284 to 288 are formed at the upper end of 8 so as to come into contact with the discharge port 401 and become lower than the upper end of the surface on the side that closes the discharge port 401.

The cap 4 is preferably a soft elastic body having a JIS hardness of 40 to 60 degrees. In this embodiment, a silicone rubber having a hardness of 45 degrees and excellent in chemical resistance is used. Chloroprene rubber or the like can be used as the material of the cap 4.

FIG. 4 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 cap 4 causes the ejection port 4 of the recording head 1 to operate.
01 is closed (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 401 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 state is not detected, the driving of the pump 18 is stopped (S201), the atmosphere opening valve 16 is opened (S202), the state in which the discharge port 401 is blocked by the cap 4 for the set time of the timer S203 is maintained, and then the cap is opened and closed. Frame 32
Is driven to separate the cap 4 from the discharge port 401.

At this time, the sensor 36 does not detect ink full as described above. That is, the ink pack 11 is in a state in which the amount of ink necessary for forming an image is insufficient, that is, the ink-end state (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 is performed for the number N1 of times S110 (S109). The operation speed when performing the rubbing operation (S109) is 5 to 10 mm / in order to ensure the removability of fixed ink and foreign matter adhering to the nozzle plate 400 described later.
It is desirable to be sec.

The state in which the discharge port 401 is closed by the cap 4 for the set time of the timer S111 is maintained, and then the cap opening / closing frame 32 is driven to discharge the discharge port 401 from the cap 4.
A wiping operation is performed to open (S112). As a result, the ink lump 410 attached to the surface of the nozzle plate 400, which will be described later, is wiped off.

After the wiping operation (S112) is performed, the scraper 22 of the waste ink container 20 scrapes off the ink lump 410 adhering to the cap 4 and absorbs it by the absorbing material 21a. The surface of the cap 4 is the absorbent material 21.
It is rubbed on b and cleaned.

A seal head 50 is mounted below the recording head 1, and the ink mass 410 dripping to the recording head 1 side by the wiping operation (S112) is absorbed by the absorbing material 21a via the scraper 22. . A soft elastic body having a JIS hardness of 20 to 30 degrees is desirable for the seal head 50. In this embodiment, a silicone rubber having a hardness of 25 degrees and excellent in chemical resistance is used.

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 401 are separated from each other. At this time, it is desirable that the speed at which the cap opening / closing frame 32 is slid downward is set to 1.0 to 2.0 mm / sec so as not to destroy the meniscus of the ejection port 401 described later.

After that, the state is maintained 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 401 is open to the atmosphere, if the pressure of the pump 18 is too high, the ink will flow out from the ejection port 401 and unnecessary ink will be consumed. To prevent this, the low pressure by the pump 18 is + 0.02 × 10E5 to 0.04 with respect to the atmospheric pressure.
It is desirable that the pressure is × 10E5 Pa.

Then, the pump 18 is stopped (S11
7) The atmosphere release valve 16 is opened (S118), and the recovery operation is finished (S119).

Here, the aforementioned wiping operation (S112)
Will be described in more detail. FIG. 5 is an explanatory diagram showing the aforementioned wiping operation (S112).

Reference numeral 400 in the drawing denotes a nozzle plate provided in the recording head 1, and the plurality of ejection ports 40 described above are provided.
1 is perforated. Note that FIG. 5 is a cross-sectional view showing one row of the ejection ports 401 arranged in a plurality of rows in the vertical direction.

The wiping operation (S112) is performed by the cap 4
The convex portion 187 and the nozzle plate 400 are brought into contact with each other, and the convex portion 187 moves downward at the relative speed V. The relative moving speed V between the nozzle plate 400 and the convex portion 187 is 3 mm / sec or less, preferably 1 mm.
/ Sec or less.

By the rubbing operation (S109) described above, the convex portion 187 moves to the vicinity of the discharge port 401 which abuts the adjacent convex portions 186 and 188. Then, adjacent inks of different colors are mixed to generate mixed color inks.

At this time, the pump 1 is installed in the recording head 1.
Due to No. 8, it is in a high pressure state. Therefore, the discharge port 40
When 1 is exposed to the atmosphere, ink flows out from the ejection port 401. Therefore, the mixed color ink does not enter the ejection port 401 by the rubbing operation (S109).

Wiping operation as shown (S112)
Then, the ink lump 410 having the mixed color ink forms the convex portion 18
It may be carried out in a state where it remains on the upper part of 7. However, since the present embodiment has the concave portion 287, the ink lump 410 at the time of the wiping operation (S112) has the concave portion 287.
Flow to. Therefore, the mixed color ink does not cause a mixed color phenomenon.

The above description of the wiping operation (S112) has been made on the convex portion 187, but the other convex portion 18 is performed.
It is clear that the same operation is achieved even when 4 to 186 and 188 contact the nozzle plate 400 and the wiping operation is performed.

Incidentally, FIG. 3B is an explanatory view showing another embodiment of the cap 4.

As shown in the drawing, the concave portions 284 to 288 are tapered so that the above-mentioned wiping operation (S11) is performed.
In the case of 2), the flow of the ink lump 410 to the recesses 284 to 288 is quickly performed, and the occurrence of the color mixing phenomenon can be further suppressed.

Further, in FIGS. 3A and 3B, by coating the surface of the cap 4 with fluorine, the water repellency of the surface of the cap 4 is improved, and the flow of the ink lump 410 to the concave portions 284 to 288 becomes faster. Further, the effect of suppressing the occurrence of the color mixing phenomenon is improved. Furthermore, the ink block 4 on the cap 4
Since a stable recovery operation can be performed without adhesion or sticking of 10, it is possible to more stably form an image.

Further, the projections 184 to 184 of FIGS.
The edge portion of 188 has an R shape as shown in the figure, but if this portion is made into a square shape, the rubbing operation (S
In 109), the removability of the fixed ink and the foreign matter attached to the nozzle plate 400 is improved.

FIG. 6 shows the pressure applied to the ink in the flow path (pressure P in the flow path) and the flow velocity of the ink in the flow path with the passage of time (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. 4, 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 atmosphere gradually returns to 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 setting the set time T1 in 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.

As described above, the rubbing operation (S10
By 9), the discharge port 401 performs an alternating operation of opening and shutting off from the atmosphere. When the ejection port 401 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 ink is ejected from the ejection port 401. 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.

Since the cap 4 and the nozzle plate 400 are in contact with each other during this rubbing operation (S109), the nozzle plate 400 and the cap 4 are rubbed together.

That is, as described above, since the ink is discharged from the ejection port 401 and the nozzle plate 400 is rubbed at the same time,
The bubbles in the discharge port 401 are discharged to the atmosphere together with the ink,
Further, ink, foreign matter, and the like fixed to the nozzle plate 400 are promptly removed. Further, since the number N1 of rubbing operations (S109) can be changed by the number of times S110, it is possible to easily change the above-described ink discharge amount and also easily change the removability of fixed ink and foreign matter.

Needless to say, the removal of the ink and the foreign matter adhered to the nozzle plate 400 is facilitated by the discharge of the ink from the ejection port 401.

Further, by performing the wiping operation of S112, the fixed ink and foreign matters around the ejection port 401 are 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 of 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 high pressure and then the low 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 performing the pressurization at the low pressure after the pressurization at the high pressure.

Even in the case of the ink that easily foams, the main bubbles flow into the sub-tank 30 by the pressurization by the high pressure, and the fine bubbles generated by the foaming by the pressurization by the high pressure are applied by the 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. 4, 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 bubbling by the high-pressure pressurization into the sub-tank 30 even when the environmental temperature is high and the bubbling is high.

Further, when the ambient temperature is low, the foamability of the ink is not so serious. Therefore, the time required for the recovery operation can be shortened by shortening the set time of S116.

By thus changing the set time of the timer S116 depending on the ambient temperature, a reliable recovery operation can be performed regardless of the ambient temperature.

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

Therefore, the rubbing operation (S10 in FIG.
9) The number of times N1 (S110) in which the number of times 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, the ink adhered to the nozzle plate 400 can be reliably removed even when the viscosity of the ink differs due to the change of the environmental temperature.

The operation speed in the rubbing operation (S109) described above is set in advance according to 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 401 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. In addition, the nozzle plate 400
The operation speed of the rubbing operation (S109) is also changed to remove the ink lump 410 adhering to the surface.
This can be surely performed by changing the number S110 of 109).

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

A meniscus of ink is formed at the ejection port 401 of the recording head 1. When a strong impact is applied to the meniscus, the meniscus breaks, and air enters the ejection port 401 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. 4, the cap 4 serves as the ejection port 401 of the recording head 1.
At the time of the operation S101 of closing the position, the moving speed of the cap 4 is set to 1.0 to 2.0 mm / sec as described above.
Therefore, the discharge port 401 can be reliably closed by the cap 4 with almost no impact on the meniscus. That is, when the cap 4 closes the ejection port 401, an unnecessary recording failure does not occur.

Further, in the operation S101 of closing the ejection port 401 of the recording head 1 with the cap 4, ink is ejected from the ejection port 401 of the recording head 1 (hereinafter, flushing operation).
By doing so, the following effects are exhibited.

During the flushing operation, the discharge port 401 is always
Since the ink is ejected more stably, the meniscus is not broken even if a slight impact is applied. Therefore, the operation S10 of closing the ejection port 401 of the recording head 1 with the cap 4 described above.
In case of 1, it is possible to further suppress the occurrence of unnecessary recording failure.

Further, it is desirable that the frequency of ink ejection for performing the flushing operation be half the frequency (maximum response frequency) of the limit of ink ejection of the recording head 1 (1 kHz in this embodiment). . By doing so, the ink ejection from the ejection port 401 of the recording head 1 becomes more stable, and the ink consumption due to the flushing operation can be reduced.

Here, the above-mentioned wiping operation (S112).
Will be further explained.

As described above, in the state of FIG. 2A after the wiping operation (S112), the ink 40 is stored in the sub tank 30.
From the ink to the ink pack 11. Therefore, the ink lump 410 that cannot completely flow into the recesses 284 to 288 of the cap 4
If there is, the ink tries to enter the ejection port 401. Ink lump 410 that has entered through the ejection port 401
Although it is a very small amount, it tends to gradually flow into the ink pack 11. In a normal recovery operation performed by a general inkjet recording apparatus, the extremely small amount of the ink lump 4
At about 10, the color mixing phenomenon does not occur.

However, when the ink pack 11 in the ink supply container 10 has a large capacity or the recovery operation is performed more than necessary by the user, the extremely small amount of the ink lump 41 is generated.
When 0 is accumulated, the color mixing phenomenon may occur in the ink 15 in the ink pack 11.

Therefore, in the flowchart of FIG. 4, a wiping operation S for opening the discharge port 401 from the cap 4 is performed.
In the state of FIG. 2A after 112, the flushing operation is immediately performed and ink is ejected to further exhibit the following effects. The frequency of ink ejection at this time is preferably half the frequency of the recording head 1 or less (2 kHz in this embodiment).

As described above, in the state of FIG. 2A, the flushing operation is immediately performed at a frequency of half or less of the maximum response frequency to stably perform ink ejection, and the wiping operation (S112) described above is performed. An extremely small amount of ink lump 410 that has entered through the ejection port 401 can be quickly discharged to the outside of the recording head 1.

Therefore, even if the ink pack 11 has a large capacity, or the user performs the recovery operation more than necessary, a color mixing phenomenon does not occur, and an image of a normal color can always be formed.

Further, the ink discharge of the flushing operation is divided into at least two times (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 more stably form a normal color image.

Further, in FIG. 6, a drive signal drive signal is input from the print head drive circuit to the print head 1 during the pressurization by the high pressure until the ink full in the sequence A is detected. By doing so, the air and the air bubbles existing in the flow path of the recording head 1 are swung, and the air and the air bubbles are more likely to 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.

By applying a drive signal to the recording head 1 which does not cause ink to be ejected from the ejection port 401 at the time of low pressure pressurization in sequence C of FIG. 6, the above high pressure pressurization is performed. By swirling the bubbles in the flow path of the recording head 1 generated by the bubbling of the sub-tank 30
The bubbles can flow.

Therefore, a more optimal recovery operation can be performed. Further, the set time S116 of pressurization of low pressure in FIG. 4 can be set to be short, and more efficient recovery operation can be performed.

FIG. 7 is a graph similar to FIG. 6 when the above-described high pressure pressurization and low pressure pressurization in the recovery operation are performed separately. As in FIG. 6, (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. 4, then opening the atmosphere release valve 16, maintaining the state for a set time, and closing the atmosphere release valve 16 again after the set time has elapsed.

By doing so, since a large amount of ink flow in the flow path can be generated by one recovery operation, more air and bubbles in the flow path can be swiftly 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 performed twice. In the flow chart of FIG. 4, after performing S116, the atmosphere release valve 16 is opened, the state is maintained for a set time, and after the set time has elapsed, 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 to 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.

[0129]

As described above, in the present invention,
A recording head having an ejection port for ejecting ink, an ink supply container for storing ink to be supplied to the recording head, an ink supply unit serving as a flow path for supplying ink to the recording head, and an ink supply container to the recording head. A step of sealing the ejection port of the recording head by the cap means, and a step of sealing the ejection port of the recording head by means of a pump means for pressure-feeding the ink and a cap means that is in close contact with the ejection port of the recording head and closing the ejection port. A step of pressure-feeding the ink of the ink supply container to the recording head by the pump means, a step of returning the internal pressure of the recording head to a normal state, a step of separating the cap means and the discharge port, and stopping the pump means for a set time, and then Inside the head without discharging ink from the discharge port by setting the pressure of the pump unit to a lower pressure than the pressure feeding by the pump unit after sealing the discharge port. Ink by performing the steps of pumping, the recovery operation consisting of a, bubbles mixed in the flow path in the recording head is discharged to the atmosphere, it can be changed easily discharge amount of ink due to the recovery operation. Further, a color mixture phenomenon due to the recovery operation does not occur, and a normal image can always be formed.

Further, the pressure in the recording head can be surely set to the high pressure of the pump. Therefore, a constant ink discharge amount can be obtained. Further, the air bubbles in the ejection port are discharged to the atmosphere together with the ink, and the ink, the foreign matter and the like fixed to the ejection 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.

Bubbles in the recording head that could not be completely discharged by high-pressure pumping and bubbles that stagnated at the stagnation point of the flow path in the recording head (where ink does not easily flow) are also wasted by low-pressure pumping. The ink can be discharged to the outside of the recording head without consuming the ink.

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, even with the ink that easily foams, 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 since the pressure feeding time of the low pressure varies depending on the detection result of the temperature detecting means, a reliable recovery operation can be performed regardless of the environmental temperature.

By making 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 ambient 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 less 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 quickly discharged to the outside of the recording head 1, a large capacity of the ink pack or the mixed color phenomenon does not occur even if the recovery operation is performed more than necessary by the user, and the color mixture is always normal. It is possible to form a color image.

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 time for pressurizing by the pump can be set to be short, the recovery operation can be performed more efficiently.

In the step of pumping 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 which 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 opening / closing step of the cap means 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 opening / closing step for 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 in the cap opening / closing step for the set time are different, so that the ink adhering to the ejection port surface can be more reliably removed. 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 or more, and thus more 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, 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 an explanatory view showing a cap in the same apparatus.

FIG. 4 is a flowchart showing a method of recovery operation.

FIG. 5 is an explanatory diagram showing a wiping operation.

FIG. 6 is a graph showing the pressure in the flow channel and the flow velocity of ink when a recovery operation is performed.

FIG. 7 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 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 184-188 convex 190-193 groove 284 to 288 recess 410 ink lumps

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41J 2/175 B41J 2/125 B41J 2/165 B41J 2/18 B41J 2/185

Claims (17)

(57) [Claims] 1. A recording apparatus provided with an ejection port for ejecting ink.
And head, an ink supply container for storing ink to be supplied to said recording head, an ink supply means for carrying a flow path for supplying ink to the recording head, a pump for pumping ink to the recording head from the ink supply Means and a cap means provided with a cap that 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 pumping the ink in the ink supply container to the recording head by a pump means; a step of returning the internal pressure of the recording head to a normal state; a step of separating the cap means and the ejection port; setting time was stopped, before the pressure of the pump means than pumping by the pump means after then sealing the discharge port as a low pressure Discharging the ink from the discharge port
An ink jet recording apparatus, wherein a recovery operation comprising a step of pressure-feeding ink into the head without being ejected is performed. 2. The recording of ink in the ink supply container
After the step of pressure feeding to the head, the inside of the recording head is
After the constant pressure condition, set the cap means for a set time.
Repeating opening and closing, discharging ink from the discharge port
A cap for sliding the cap and the discharge port
The method further comprising a means opening / closing step.
The inkjet recording device described. 3. The recording head is provided on an upper end portion of the cap.
Lower than the top of the surface that closes and closes the discharge port of the lid.
Contractor characterized by forming a concave portion
The inkjet recording apparatus according to claim 1. 4. The discharge ports of the plurality of rows are closely contacted and the discharge ports are closed.
The twisting cap is a portion that abuts the ejection ports of each of the plurality of rows.
A groove is provided between the two, or
3. The inkjet recording device according to item 3. 5. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus includes temperature detecting means for detecting an ambient temperature, and the pressure feeding time of the low pressure varies depending on a detection result of the temperature detecting means. . 6. The ink jet recording apparatus according to claim 5, wherein the low pressure feeding time is longer when the environmental temperature is higher than when the environmental temperature is low. 7. 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 means. 8. The ink jet recording according to claim 7, wherein the frequency at which ink is ejected in the step of sealing the ejection port of the recording head is equal to or less than half the maximum response frequency of the recording head. apparatus. 9. 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 with the cap means. 10. The ink jet recording apparatus according to claim 9, wherein after the step of opening the ejection port, the ejection of the ink from the ejection port is performed at least twice. 11. 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. The inkjet recording device according to 1. 12. 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. 13. When setting the cap means and the discharge port
3. The inkjet recording apparatus according to claim 2, wherein in the opening / closing step of opening / closing the cap means, the number of times of opening / closing the set time is different depending on the detection result of the temperature detecting means. 14. When setting the cap means and the discharge port
3. The ink jet recording apparatus according to claim 2, wherein in the step of opening and closing the cap means for opening and closing, the operation speed of opening and closing for the set time differs depending on the detection result of the temperature detecting means. 15. 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. The inkjet recording device according to claim 1. 16. The ink jet recording apparatus according to claim 1, wherein 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. Recording device. 17. A method for determining whether or not the ink in the ink supply container is ink-end during 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 inkjet recording apparatus according to claim 1, which is performed.