JP3217645B2 - Ink jet recording apparatus and ink ejection recovery method in the apparatus - 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 recording apparatus.

[0002]

2. Description of the Related Art In an ink jet recording apparatus, since recording is performed by directly discharging ink from a discharge port of a recording head, it is necessary to always keep the ink in a dischargeable state, and therefore special consideration is required. .

That is, since the ink remains in the liquid path in the recording head even during non-recording, it is necessary to take measures to prevent the ink in the liquid path from changing in quality such as an increase in viscosity due to drying or evaporation of the ink. In addition, a capping means for preventing the ink from drying or evaporating by covering the ejection port forming surface (face surface) of the recording head with a cap (lid) during non-printing is adopted.

However, it is difficult to maintain a dischargeable state only by the capping operation in a low-humidity environment or during a long period of rest.

For this reason, a pressure is applied to the liquid path in the recording head by a pump or the like together with the capping means, or a negative pressure is applied to the liquid path by sucking air in the cap. A recovery mechanism has been used in which the deteriorated ink that has accumulated in the liquid path is discharged from the discharge port.

[0006] In addition, replacement of the ink cartridge,
When the printing apparatus is stopped for a long period of time, air bubbles may stay in the print head (for example, a common liquid chamber) or other ink flow paths. Discharge failure such as complete discharge occurs.

For this reason, ink is supplied to the recording head from an ink tank through an ink supply flow path by a pump or the like, and the ink is supplied from the ejection port to the cap with the cap attached to the face surface (in a capping state). The ink with increased viscosity near the discharge port (thickened ink) is discharged by circulating and collecting the remaining ink from the recovery flow path into the ink tank while treating the remaining ink as waste ink. The air bubbles in the ink flow path are collected together with the ink in the ink tank.

At this time, the inlet of the ink supply passage and the outlet of the ink recovery passage are provided at both ends of the common liquid chamber so that the ink can be easily circulated in the common liquid chamber during ink circulation.

Further, a part of the ink discharged by the recovery operation adheres to the face surface. In order to remove the ink adhered to the face surface, a wiping member (wiping member) is pressed against the adhered ink. There is also used a removing means (a head cleaning means) for wiping off the ink or blowing air from an air nozzle to blow off the attached ink.

[0010]

However, in the case of the above-described prior art, when the ink near the ejection port with increased viscosity is ejected as ejected ink, the ink near the ejection port is ejected while circulating the ink. The flow path resistance is very large because the cross-sectional area of the outlet is very small. However, the ink discharge flow path has a smaller flow path resistance. Therefore, the amount of ink circulating in the ink recovery flow path becomes extremely large as compared with the amount of ink discharged from the discharge port.

Therefore, in order to discharge the thickened ink from the discharge port, it is necessary to circulate much more ink than the ink discharged from the discharge port, and it is necessary to operate the pump for a long time. There was a problem.

Further, although ink is supplied by the pump, pressure loss occurs in the common liquid chamber, so that a portion close to the ink supply channel and a portion far from the ink supply channel (a portion near the ink recovery channel). And the pressure applied to the ink is different. In other words, a large pressure is applied to the ink in a portion near the ink supply channel, but a small pressure is applied to a portion far from the ink supply channel (a portion near the ink recovery channel).

Accordingly, a large amount of ink is discharged at the discharge port near the ink supply flow path, and the discharge port far from the ink supply flow path, that is, at the discharge port near the ink recovery flow path. The amount of ink used is reduced.

For this reason, when the pump is operated to discharge the amount of ink necessary for completely discharging the thickened ink at the discharge port far from the ink supply flow path, the pump near the ink supply flow path is operated. Unnecessary waste ink is ejected from the ejection ports, and as a result, the amount of ink used for recording is reduced. In particular, when the number of nozzles of the recording head was increased to increase the recording width of the head, the tendency was remarkable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to reduce the amount of ink discharged from a discharge port and shorten the operation time of a pump. An object of the present invention is to provide a small, inexpensive, quiet, highly reliable ink jet recording apparatus with stable ink ejection.

Another object of the present invention is to provide a method for recovering the ejection of an ink jet recording apparatus which is highly efficient in a short time.

[0017]

According to the present invention, there is provided a recording medium comprising:
Discharge port for recording by discharging ink, and communicating with the discharge port
A recording head having an ink liquid chamber,
An ink tank for containing ink to be supplied to the i
First ink for communicating the ink liquid chamber and the ink tank
A passage provided separately from the first ink passage;
A second ink communicating between the ink liquid chamber and the ink tank.
And click passage, provided in the first ink passage, the in-
For pumping ink from the ink tank to the ink liquid chamber.
A first pump , provided in the second ink passage,
Direction from the ink tank to the ink liquid chamber,
Is the direction from the ink chamber to the ink tank.
The second that can change the ink flow direction to either
Providing an ink jet recording apparatus characterized by comprising: a pump, a. In this case, the second pump is
It may be a pump.

According to the present invention, scanning is performed on a recording material.
A recording head that discharges ink onto the recording material
An ejection port for performing recording, and an ink liquid chamber communicating with the ejection port.
A recording head comprising:
An ink tank containing ink, the ink liquid chamber,
A first ink passage communicating the ink tank, the first
The ink chamber is provided separately from the ink passage,
A second ink passage for communicating the serial ink tank, wherein
Connecting a first ink passage with the second ink passage
A third ink passage, and a third ink passage provided in the first ink passage.
And pressurizes ink from the ink tank to the ink liquid chamber.
A pump for feeding the ink , and a pump provided in the third ink passage.
A first passage opening and closing for opening and closing the third ink passage.
Means, the second ink passage and the third ink passage
The second ink between the connection portion with the ink tank and the ink tank.
And is provided in the ink passage to open and close the second ink passage.
Second passage opening / closing means, the first passage opening / closing hand
Step and at least one of said second passage opening and closing means.
Opening and closing in conjunction with the scanning of the recording head.
The present invention provides an ink jet recording apparatus characterized by the following. this
In this case, the first passage opening and closing means and the second passage opening and closing means
It may be a valve.

[0019] In the ink jet recording apparatus of the present invention described above, but it may also be provided with a discharge port sealing means for sealing the discharge opening.

Further, in the ink jet recording apparatus according to the present invention, the first ink passage and the second ink passage are provided.
Filter for each dust removal road may have been eclipsed set.

Further, in the ink jet recording apparatus of the present invention, the recording head is used for discharging ink.
Heat that causes film boiling in the ink as energy
It may have an element that generates energy .

Further, according to the present invention, there is provided an ink jet recording apparatus comprising the first pump and the second pump in the above-mentioned ink jet recording apparatus.
Ink recovery method for an ink jet recording apparatus.
Thus, the first ink passage is formed by the first pump.
Ink from the ink tank to the ink liquid chamber through
Supply and the second pump
The ink liquid from the ink tank through an ink passage;
Supplying ink to a chamber, and discharging ink from an ejection port of the recording head, an ink ejection recovery method ,
And the first ink passage by the first pump
Ink from the ink tank to the ink liquid chamber through
And the second pump
From the ink liquid chamber through the ink passage of
Ink to the first ink passage and the ink
Ink in the ink chamber and the ink in the second ink passage.
A method for recovering ink discharge, which is characterized by circulating, is provided.

The present invention further provides a first passage opening / closing means and a second passage opening / closing means in the above-mentioned ink jet recording apparatus.
Discharge in an ink jet recording apparatus having means
Exit recovery method, wherein the second passage opening and closing means is closed
Blocks the flow of ink and opens the first passage opening / closing means
Then, the pump is operated in a state where the ink flows.
Discharging ink from the discharge ports of the recording head.
A method of recovering ink discharge, and the first communication method.
Closing the path opening / closing means to cut off the flow of ink,
As a state in which the ink flows opens the passage opening and closing means, prior
The present invention provides an ink ejection recovery method characterized in that the pump is operated to circulate the ink in the first ink passage, the ink liquid chamber in the recording head, and the ink in the second ink passage.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS ( Reference Example ) Before describing an embodiment of the present invention, a reference example of the present invention will be described with reference to FIGS.

FIG. 1 is a perspective view of a main part of an example of a full-line type ink jet recording apparatus as a reference example of the present invention, and FIG. 2 shows the constitution of the ink jet head and ink passage of such an ink jet recording apparatus. FIG. FIG. 3 is a sectional perspective view of the cap in FIG. 1, and FIG. 4 is a transverse sectional view of the cap in FIG. FIG. 5 to FIG.
FIG. 4 is a schematic side view illustrating the operation of the inkjet head and the cap. FIGS. 11 and 12 are schematic views of the ink jet head, ink passages, and valves showing the flow of ink near the ink jet head.

As shown in FIG. 1, a recording material 2 loaded on a cassette 1 removably provided in an ink jet recording apparatus is fed one by one by rotating a feed roller 3, and a motor is provided. The paper feed system motor driven by the driver 34 rotates the feed roller pair 5 to convey the recording material to the recording material conveyance system 4.

The recording material transport system 4 includes an endless transport belt 7 for transporting the recording material 2 to be fed, and idle rollers 8 arranged at a plurality of predetermined positions for stretching the endless transport belt 7. Pinch rollers 13A and 13B pressed against the idle roller 8 via the endless transport belt 7, a tension roller 9 for applying a predetermined tension to the endless transport belt 7, and a belt for driving the endless transport belt 7 Drive roller 10 and its belt drive roller 10
And a motor driver 31 for driving the motor 11.

The recording material 2 transported to the recording material transport system 4
Performs a registration operation in which the tip abuts on a nip formed by the pinch roller 13A and the endless transport belt 7 and is bent and held along the transport guide 6 so as to align the tip in a direction orthogonal to the transport direction.

Thereafter, the recording material 2 is charged by the charger driver 3
3, a potential difference is generated between the transfer belt 7 and the transfer belt 7, which is charged and removed by the charger 12, and is connected to the belt transfer roller 10 by a pressing effect of the pinch rollers 13A and 13B and an electrostatic attraction effect due to the potential difference. Is conveyed in the direction of the arrow X in a state of being tightly adhered to the convey belt 7 driven by the driven motor 11.

At this time, the ink jet head 20 ejects ink by a head driver 32 for selectively supplying a recording signal to the ink jet head 20 while sequentially adjusting the timing in accordance with the position of the recording material 2. Recording is performed on the recording material 2, and the four inkjet heads 20A, 20B, 20C, and 20D
A full-color recording using four colors of black, cyan, magenta, and yellow is completed.

The ink-jet recording apparatus can record a high-definition image at a high speed, and is a non-impact type. Therefore, the noise is small, and it is easy to record a color image using multi-color ink. There are advantages such as.

A recording head in the ink jet recording system includes a liquid discharge port for discharging a recording ink liquid as a flying droplet, a liquid flow path communicating with the discharge port, and a part of the liquid flow path. A discharge energy generating means for providing discharge energy for causing the ink liquid in the flow path to fly. Then, the ejection energy generating means is driven according to the image signal to eject ink droplets to generate an image.

As the ejection energy generating means, for example, a method using a pressure energy generating means such as an electromechanical transducer such as a piezo element, or an electromagnetic energy generating a flying droplet by irradiating an ink liquid with an electromagnetic wave such as a laser and absorbing it. There is a method using a generating means, or a method using an energy generating means for discharging the liquid by heating the liquid with an electrothermal converter such as a heating element having a heating resistor.

Among them, a recording head used in an ink jet recording method in which a liquid is ejected by thermal energy has a high density of liquid ejection ports for ejecting recording droplets and forming ejection solution droplets. Therefore, high-resolution recording can be performed.

Among them, the recording head used as a means for generating thermal energy of the electrothermal converter is easy to make compact, and has recently achieved remarkable advances in technology and reliability in the semiconductor field, such as IC technology and microelectronics. This is advantageous because the advantages of processing can be fully utilized, high-density mounting is easy, and manufacturing costs are low.

Referring to FIG.
On the upper surface of the aluminum head base 41, a driver 4
4 and a silicon substrate 42 are joined, and a resin cover 43 is joined to the upper surface of the silicon substrate 42.

A heating element (not shown) for generating discharge energy is provided in each of the liquid passages 47 on the silicon substrate 42.
Are arranged.

The driver 44 is connected to the silicon substrate 4
2 and an electric circuit for driving the heating element.

A liquid passage 47 is formed in the resin cover 43 so as to communicate with the ink common liquid chamber 45 and each of the discharge ports 46. A liquid path 47 leading to the discharge port is formed.

Since the silicon substrate 42 is very expensive, it is necessary to reduce the cost by reducing the area as much as possible. For this reason, the silicon substrate 42 communicates with the common liquid chamber 45 formed in the resin cover 43 and each discharge port. It is necessary to make the liquid passage 47 as small as possible so that the area of the resin cover 43 in close contact with the silicon substrate 42 is reduced.

For this reason, the flow path resistance in the common liquid chamber 45 is higher than the other ink flow paths.

An ink supply passage (tube) 28, which is a first ink passage, is connected to one end of the common liquid chamber 45.
The other end of the common liquid chamber 45 is connected to an ink recovery passage (tube) 38 which is a second ink passage. A filter 49 made of a metal mesh is provided at this connection portion. When the ink supply head 28 and the ink discharge tube 38 are detached when the ink jet head 20 is attached to the apparatus or when the ink jet head 20 is replaced, dust or the like is shared. The liquid does not enter the liquid chamber 45 and the liquid path 47 leading to each discharge port, and does not hinder the flow of ink.

The ink supply tube 28 and the ink collection tube 38 are connected by an ink bypass tube 39 serving as a third ink passage. 5
6 is provided so that opening and closing of the passage can be controlled.

A second solenoid valve 55 as a flow path opening / closing means is provided at an ink discharge tube 38A portion closer to the ink tank than the connection portion between the ink collection tube 38 and the ink bypass tube 39, and similarly, the passage is opened and closed. Can be controlled.

As described above, in the case of a recording apparatus having a plurality of ink jet heads 20A to 20D as shown in FIG. 1, the structure of the ink jet head 20 described in FIG. It will be implemented in the same manner above.

The ink tank 21 is a single head 20
Four tanks 21A, 21B, 21C, 21 for supplying inks of colors corresponding to A, 20B, 20C, 20D
D.

The ink supply passage (tube) 28, the ink recovery passage (tube) 38, the ink bypass passage (tube) 39, and the ink pump 29 are respectively composed of four ink jet heads 20A to 20D and four ink tanks 21A to 21A. 21D, four ink supply passages (tubes) 28A, 28B, 28C, 28D;
Four ink recovery passages (Tupes) 38A, 38B, 3
8C, 38D; 4 ink bypass passages (tubes)
39A, 39B, 39C, 39D; and four ink pumps 29A, 29B, 29C, 29D.

The ink in each of the ink tanks 21A to 21D driven by the pump driver 35 is supplied to the corresponding head unit 20A to 20D through the corresponding ink supply tube 28A to 28D. The head in the tanks 21A to 21D is kept lower by a predetermined height than the ejection port forming surface (face surface) 48 of each of the heads 20A to 20D, and the ink ejected at the time of recording is a capillary phenomenon in the ink flow path. Is supplied to each head unit 20 by utilizing the above.

The ink tanks 21A, 21B, 2
1C and 21D are provided with a hole (vent) through which an air reservoir of about 20% of the initial volume and the air flow.

The four ink jet heads 20A, 20
B, 20C, and 20D are held by the holder 2 so that the intervals (pitch) of the ejection ports 46 in the recording material conveyance direction are constant.
The head unit 24 fixed at 3 is movable up and down by a head moving means 25.

The cap 2 attached to the ejection port forming surface (face surface) 48 of the ink jet head 20 during non-recording
Numeral 2 can be moved by the cap moving means 26 in the recording material transport direction (X direction) and the opposite direction.

The cap 22 is connected to the four ink jet heads (heads 20A, 20B, 20C,
0D), four caps 22A, 22B, 2
2C and 22D.

The four caps 22A, 22B, 2
As shown in FIGS. 3 and 4, a sponge-like ink absorbing member 52 for holding ink to be ejected from the ejection port 46 (empty ejection) is housed inside the 2C and 22D.

These caps are used for the head unit 20.
A, 20B, 20C, and 20D are arranged at the same interval, and are fixedly supported so that the heads 20A to 20D can be simultaneously crowned. In addition, each of the caps 22
As shown in FIGS. 3 and 4, an opening 51 for opening the ejection port 46 of the face surface 48 of each head unit (inkjet head) 20 to the inside of the cap is formed at the center of the upper surface. A sponge-like ink absorbing member 52 for holding ink to be ejected from the ejection port 46 (empty ejection) is accommodated therein.

The ink in the ink tank 21 can be supplied to the common liquid chamber 45 in the ink jet head through the ink supply tube 28 by operating the ink pump 29.

FIG. 5 shows a state in which the power is off, and the face surface 48 of the ink jet head (each head alone) 20 is
The ink is adhered to the cap 22 to prevent evaporation of the ink from each ejection port 46.

In this state, when the power is turned on, first, the head unit 24 (inkjet head 20) is lifted by about 1 mm by the head moving means 25 (FIG. 1), and the state shown in FIG. 6 is obtained.

When the ink is circulated in the common liquid chamber in the state of FIG. 6, the cap moving means 26 moves the cap 22 in the direction opposite to the X direction (recording material conveyance direction) in FIGS. 3 and 4. 7, and is joined to a position (edge in the illustrated example) of the upper surface of the cap that is outside the opening as shown in FIG. Is set in such a manner that the sealing member 53 and the discharge port 46 match.

The sealing member 53 is usually made of a rubber-like elastic material, and the face surface 48 of each ink jet head 20 is formed.
Are used as discharge port sealing means for sealing the discharge port array (all discharge ports).

Next, the ink jet head 20 is depressed and the sealing member 53 is pressed against the discharge port row, thereby
After closing all the discharge ports of the line to the state shown in FIG. 8, the first solenoid valve 5 provided in the ink bypass tube 39 is used.
6 is closed, the second solenoid valve 55 provided on the ink discharge tube 38 is opened, and the ink pump 29 is operated in this state, and the ink tank 21 → the ink pump 29 → the ink supply tube as shown by the arrow in FIG. 28 → Common liquid chamber 4
The ink is circulated in the order of 5 → ink recovery tube 38 → second solenoid valve 55 → ink recovery tube 38 → ink tank 21.

After the ink circulation is performed at a predetermined flow rate for a predetermined time, the ink jet head 29 is lifted to
Then, the cap 22 is moved by the distance L (FIG. 4) in the X direction to return to the position of the cap set in FIG.

This ink circulation operation is performed not only when bubbles in the common liquid chamber are removed but also when the ink and the ink jet head are heated by thermal energy generated at the time of recording and a discharge failure occurs. The cooling of the head can also be performed.

When removing thickened ink or bubbles in the liquid passage 47 from the common liquid chamber 45 to each discharge port, the first solenoid valve provided in the ink bypass tube 39 in the state of FIG. 56 is opened and the ink collection tube 3
8, the ink pump 21 is operated in this state, and ink is supplied from the ink tank 21 to the ink pump 29 to the ink supply tube 28 to the common liquid as shown by the arrow in FIG. The ink is supplied to the chamber 45 and the ink tank 21 → the ink pump 29 → the ink supply tube 28 → the ink bypass tube 39 → the first solenoid valve 56 → the ink recovery tube 38 → the common liquid chamber 45.

At this time, the flow path resistance from the ink bypass tube 39 through the ink recovery tube 38 to the common liquid chamber 45, and the flow path of the ink supply tube 28 on the common liquid chamber side 45 from the connection with the ink bypass tube 38. If the resistance is the same, the amount of ink entering from the ink supply tube 28 and the amount of ink entering the common liquid chamber 45 from the ink collection tube 38 through the ink bypass tube 39 will be the same. In this state, the ink is pressurized and flows in from both ends of the common liquid chamber 45 with the same pressure, so that the ink pressures in the common liquid chamber 45 and the liquid passages 47 leading to the respective discharge ports are substantially uniform, and the respective discharge The same amount of ink is discharged from the flow path to the outlet,
The thickened ink and bubbles are pushed out of the nozzle.

The pressurization and discharge of the thickened ink is usually performed when the power is turned on and every time about 100 sheets of recording are performed by continuous paper feeding.

Further, the pressurization and discharge of the thickened ink is also performed when a user inputs a signal by operating a button or the like when recording unevenness or the like occurs.

Thereafter, the cap 22 is moved in the direction opposite to the X direction by the cap moving means 26 so as to be retracted from the ink jet head 29 as shown in FIG.
In a state that can be accommodated.

Then, the ink jet head 29 is lowered by the head moving means 25 and set at a position where the distance between the face surface 48 and the surface of the conveyor belt 7 is about 1 mm, that is, at the recording position shown in FIG.

At the time of recording, first, the paper feed roller 3 is driven,
Recording material (recording sheet such as paper) in paper cassette 1
The recording material 2 is picked up one by one and guided between a pair of feeding rollers 5. The leading end of the recording material 2 is constituted by an endless transport belt 7 pressed against an idle roller 8 by the feeding roller pair 5, and a pinch roller 13A. The recording material 2 is further fed from the state, a loop is formed in the space of the mountain-shaped conveyance guide 6, and the entire tip portion follows the nip portion due to the waist of the recording material 2, The orthogonality between the leading edge of the recording material and the transport direction is ensured.

Next, the belt motor 11 and the charger 12
Is turned on, and the recording material 2 is guided between the chargers 12 while being pressed against the transport belt 7 by the pinch rollers 13A.

The charging device 12 has a +
The lower side is negative, and a potential difference is generated between the conveyance belt 7 and the recording material 2 from which electricity is removed just before the pinch roller 13A, and the recording material 2 is attracted to the conveyance belt 7 by electrostatic force.

In this case, the pressure contact of the pinch roller 13B after passing through the charger 12 further ensures that the recording material 2 is attracted to the surface of the conveyor belt 7.

As described above, the recording material 2 is conveyed,
After the leading end of the recording material 2 reaches the inkjet head 20 while counting the transport of the recording material 2 in synchronization with the activation of the belt motor 11, ink is ejected from the inkjet head 20 to perform recording. When a plurality of inkjet heads are used, recording of each color is performed sequentially after the leading end of the recording material 2 reaches each inkjet head.

The recording material 2 on which recording has been completed is separated from the rear end of the conveyor belt 7 by a curvature and is discharged to a discharge tray 15.

When the discharge (discharge) of the recording material 2 is completed,
The belt motor 11 and the charger 12 are turned off.

Subsequently, when recording is performed,
Subsequently, the paper feed roller 3 is driven to perform the above operation.

When recording is completed, the head unit 24
(Inkjet head 20) is raised by head moving means 25 to the state shown in FIG. 9, and then cap unit 22 is moved by a predetermined amount in the X direction by cap moving means 26 to return to the state shown in FIG. 24
Is depressed to bring the state of FIG. 5 in which the cap 22 is mounted on the face surface 45 of each ink jet head alone.

In this capping state, all of the discharge ports 46 arranged in a line are
, And is open to the space inside the cap 22.

In this state, the power is turned off to complete the recording operation.

The supply of the ink consumed by the ejection at the time of recording is performed from one or both of the ink supply tube 28 and the ink collection tube 38. The operation is performed by a capillary phenomenon in the inkjet head 20 with one or both of the valve 56 and the second electromagnetic valve 55 opened.

[0081] In the above example, using the belt 7 and the electrostatic attraction means 12 as a conveying means for the recording material 2, instead of this, such as a method that uses an air suction or drum by the belt, the other A scheme can also be used and a similar effect can be achieved.

Further, as the discharge port closing means for closing the discharge port 46, a rubber-like sealing member 53 provided on the cap 22 is used, but this can be constituted by an independent member different from the cap 22. Further, a sealing member made of another material such as a soft plastic can be used.

In the present embodiment , the ink supply tube 28 as the first ink passage and the ink collection tube 38 as the second ink passage are connected to the junction between the ink bypass tube 39 as the third ink passage. Also provided a filter 49 for dust removal on the common liquid chamber side, respectively.
From the time of manufacturing the ink jet head, or at the time of assembly or replacement, when each of the first ink passage and a part of the second ink passage and the third ink passage can be treated integrally with the ink jet head, It is also possible to arrange filters on the ink tank side of the joint between the first and second ink passages and the third ink passage, that is, on the opposite side of the common liquid chamber to the joint.

Hereinafter, embodiments of the present invention will be described. Example 1 (Example 1) The present invention will be described with reference to FIGS. 13 to 16.

FIG. 13 is a sectional view of a main part of a recording section of an ink jet recording apparatus embodying the present invention, and FIG.
FIG. 3 is a perspective view of a head carriage unit on which an inkjet head of the inkjet recording apparatus embodying the present invention is mounted. FIGS. 15 and 16 are cross-sectional views of a main part of the recording unit when the recording unit is viewed from the recording paper conveyance direction for explaining a state during the recovery operation.

The configuration of the entire apparatus according to the present embodiment is almost the same as that described in the reference example , and the same portions are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the ink jet head 63
Is provided on the head carriage 64 and performs image recording in a so-called serial scan system in which recording is performed by scanning the head carriage 64. The ink supply tube 28, the ink collection tube 38, and the bypass tube 39 are made of plastic. 39 parts of bypass tube and ink collection tube 3 made of material (for example, silicone )
Eight parts are provided with valves 66 and 67 for restricting the flow of ink by collapsing the tubes at the same position as in the reference example, and the carriage is moved to turn the valves on and off.

Recording medium 2 fed and conveyed from a cassette
Is transported to a recording position on a platen 62 by a pair of transport rollers 60 and 61.

In this state, the head carriage 64 on which the ink jet head 63 is mounted is moved in a direction perpendicular to the direction of transport of the recording material (a direction perpendicular to the plane of FIG. 13 and the direction of arrow Y in FIGS. 14 to 16). H, rail 65
And recording is performed by ejecting ink to the recording material 2.

Thereafter, the recording paper 2 is conveyed by the conveying roller pair 60 and 61 by the recording width of the ink jet head 63, and the recording is repeated to record on the entire surface of the recording paper 2.

The ink supplied to the ink jet head 63 is supplied from the ink tank 21 by the ink supply tube 28 by the ink pump 29 in the same manner as in the reference example, and the ink circulated through the ink collection tube 38 is supplied to the ink tank 21. It is configured to return to.

The ink supply tube 28 and the ink recovery tube 38 allow the ink to flow between the ink jet head 63 mounted on the head carriage 64 and the ink pump 29. In order to avoid this, they are arranged in a U-shape as shown in FIGS. 15 and 16 along the scanning direction (Y direction) of the head carriage.

Further, a closed sub-tank 68 for storing ink is provided in the head carriage portion in the middle of the ink supply tube 28.

To circulate the ink in the common liquid chamber 45, first, the head carriage 64 is located at a position where the discharge port 46 on the face surface of the ink jet head 63 faces the sealing member 53 provided on the cap 22 as shown in FIG. To move. At this time, the first sealing member 66a constituting the first valve 66 provided on the head carriage 64 crushes the ink bypass tube 39 by the first slope 66b provided on the apparatus main body, and stops the flow of ink. Let it. Then, in the state of FIG. 15, the cap 22 is moved in the head direction (Z direction) by cap driving means (not shown), and the sealing member 53 is pressed against the row of discharge ports to seal all the discharge ports in one line.

In this state, the first valve 66 shown in FIG.
Is a state in which the ink bypass tube 39 is crushed by the first sealing member 66a.
The second valve 67 provided in the eight section is not in a state where the second sealing member 67a crushes the ink collection tube 38 due to the second slope 67b provided in the apparatus main body.

[0096] Here, by operating the ink pump 29, participants
The ink is circulated in the order of the ink tank 21 → the ink pump 29 → the ink supply tube 28 → the common liquid chamber 45 → the ink recovery tube 38 → the ink tank 21 in the same manner as in the example.

After the ink circulation has been performed at a predetermined flow rate for a predetermined time, the cap 22 is retracted, and then the head carriage 64 is moved from the ejection port array to the cap 2 as shown in FIG.
2 to the position opposite to the opening of
Is moved in the direction (Z direction) of pressing against the ink jet head 63, and is returned to the position of the cap set in FIG. 5 in the reference example .

In the state shown in FIG. 16, the second valve 6
The sealing member 67a that constitutes 7 crushes the ink discharge tube 38 by the second slope 67b provided in the apparatus main body, and stops the flow of ink. The first valve 66 does not obstruct the flow of the ink in the ink bypass tube 39 because the first sealing member 66a has passed the slope 66b.

Liquid path 4 from common liquid chamber 45 to each discharge port
In order to remove the thickened ink and bubbles in 7, the ink pump 21 is operated in the state of FIG. 15 (FIG. 6),
As shown by the arrows in FIG. 12 in the reference example , the ink tank 21 → ink pump 29 → ink supply tube 28 → common liquid chamber 45 and ink tank 21 → ink pump 29 → ink supply tube 28 → ink bypass tube 39 → Ink recovery tube 38 → Common liquid chamber 45
Supply by the route.

At this time, the flow path resistance from the ink bypass tube 39 to the common liquid chamber 45 through the ink recovery tube 38 and the flow path of the ink supply tube 28 on the common liquid chamber 45 side from the connection portion with the ink bypass tube 38. If the resistance is the same, the amount of ink entering from the ink supply tube 28 and the amount of ink entering the common liquid chamber 45 from the ink collection tube 38 through the ink bypass tube 39 will be the same. In this state, the ink is pressurized and flows in from both ends of the common liquid chamber 45 at the same pressure, so that the ink pressure in the liquid path 47 leading to the common liquid chamber 45 and each of the discharge ports becomes substantially equal, and The same amount of ink is pushed out from the flow path to push out thickened ink and bubbles out of the nozzle.

In this embodiment, the ink jet head 63
Although only one is mounted on the head carriage 64 to perform mono-color image recording, a full-color image can be recorded by providing four inkjet heads.

[0102] Further, when circulating the ink in both of Reference Example 1 in the common liquid chamber, a discharge port array sealed by the sealing member, ink is supplied by a pump, it was drained from the ink collection tube However, a pump is provided in the middle of the ink collection tube without using a sealing member, and the pump provided upstream of the ink supply tube and the pump provided in the middle of the ink collection tube are simultaneously operated,
The ink in the common liquid chamber is circulated by making the amount of ink that is sent from the ink supply tube to the common liquid chamber and the amount of ink that is forcibly collected from the ink collection tube by the pump from the common liquid chamber substantially the same. It is also possible.

Further, by setting the flow rate of the ink flowing through the pump provided in the middle of the ink recovery tube to be smaller than the flow rate of the ink flowing through the pump provided upstream of the ink supply tube, It is possible to simultaneously perform the circulation of the ink and the pushing out of the thickened ink and air bubbles in the flow path to each discharge port to the outside of the nozzle.

Embodiment 2 A second embodiment will be described with reference to FIG.

FIG. 17 is a diagram showing the principal part of the ink circulation from the ink tank to the ink jet head in this embodiment, and other recording paper transport mechanisms and operations are the same as those described in the reference example. The components are equivalent, and the same portions are denoted by the same reference numerals and description thereof will be omitted.

In this embodiment, the first pump pressurizes the ink into the common liquid chamber between the ink supply tube and the ink tank, and pressurizes the ink into the common liquid chamber between the ink collection tube and the ink tank. A second pump is provided for applying a negative pressure to the ink in the liquid chamber.

Since the second pump needs to be a pump capable of sending ink in two directions, in this embodiment, the tube is crushed by a roller and the roller is moved on the tube. The ink is sent by changing the pressure by causing a volume change in the tube, that is, by using a so-called tube pump and changing the rotation direction of the roller to change the ink sending direction.

To circulate the ink in the common liquid chamber 45, the ink is supplied from the ink supply tube 28 to the common liquid chamber 45 (in the direction of arrow A) by the first ink pump 29, and at the same time, the ink is supplied to the second ink pump 29. The roller holder 72 holding the roller 71 constituting the ink pump 70 is rotated in the direction of arrow B in FIG. 17, and the ink collection tube 38 is rotated by the roller 71 and the tube holding portion 73 while being crushed to cause a volume change. Then, the ink is discharged from the common liquid chamber 45 to the ink tank 21. Here, by making the flow rates of the first ink pump 29 and the second ink pump 70 substantially the same, the ink in the common liquid chamber of the inkjet head 20 can be circulated.

A roller 71 is provided in the ink collection tube 38 between the second ink pump 70 and the common liquid chamber 45.
In order to reduce the pulsation of the ink due to the pressure change that occurs when the ink comes into contact with or detaches from the tube, a pulsation reduction tank 74 that holds the air in a sealed state and obtains a damping effect is provided.

Further, in order to remove thickened ink and bubbles in the liquid passage 47 (FIG. 2) from the common liquid chamber 45 to each discharge port, the ink is supplied from the ink supply tube 28 by the first ink pump 29. In liquid chamber 45 (direction of arrow A)
By supplying the ink and rotating the roller holder 72 of the second ink pump 70 in the direction of arrow D, the ink is sent in the direction of arrow E in the ink collection tube 38, and the ink is transferred from the ink tank 21 into the common liquid chamber 45. Supply to reference
The same effects as in the example and the first embodiment can be obtained.

In this embodiment, when the flow rate of the second ink pump is set to be smaller than the flow rate of the first ink pump during the circulation of the ink, the circulation of the ink and the discharge of the thickened ink in the liquid path are simultaneously performed. It is also possible to perform while controlling the discharge amount.

[0112]

As described above, according to the present invention, a small, inexpensive, quiet, and stable ink discharge can be achieved by reducing the amount of ink discharged from the discharge port and shortening the operation time of the pump. A reliable inkjet recording apparatus can be obtained, and a highly efficient ejection recovery method of the inkjet recording apparatus can be obtained in a short time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part showing a configuration example of an ink jet recording apparatus of the present invention.

FIG. 2 is a perspective view illustrating a configuration example of an ink jet head and an ink passage in the ink jet recording apparatus of the present invention.

FIG. 3 is a sectional perspective view of one example of a cap of the ink jet recording apparatus of the present invention.

FIG. 4 is a cross-sectional view of the cap of FIG.

FIG. 5 is a schematic cross-sectional view showing a power-off state of the operation of the cap of the inkjet recording apparatus of the present invention.

FIG. 6 is a schematic cross-sectional view showing a state in which power is turned on during operation of the cap of the ink jet recording apparatus of the present invention.

FIG. 7 is a schematic cross-sectional view showing a state in which the position of a discharge port and a sealing member separated by a predetermined distance coincide with each other during the operation of the cap of the ink jet recording apparatus of the present invention.

FIG. 8 is a schematic cross-sectional view showing a state in which the discharge port and the sealing member are pressed against each other during the operation of the cap of the ink jet recording apparatus of the present invention.

FIG. 9 is a schematic cross-sectional view showing a state in which the cap is retracted from the ink jet head during the operation of the cap of the ink jet recording apparatus of the present invention.

FIG. 10 is a schematic cross-sectional view showing a state during recording in the operation of the cap of the ink jet recording apparatus of the present invention.

FIG. 11 is a schematic diagram illustrating an example of the flow of ink during an ejection recovery operation in the inkjet recording apparatus of the present invention.

FIG. 12 is a schematic diagram illustrating another example of the flow of ink in the ejection recovery operation in the inkjet recording apparatus of the present invention.

FIG. 13 is a sectional view of a main part of a recording unit of the ink jet recording apparatus of the present invention.

FIG. 14 is a perspective view of a head carriage unit on which the inkjet head of the inkjet recording apparatus of the present invention is mounted.

FIG. 15 is a cross-sectional view of the recording unit viewed from a recording paper conveyance direction, for describing a state during a recovery operation in the inkjet recording apparatus of the present invention.

FIG. 16 is a sectional view of a main part of the recording unit of FIG.

FIG. 17 is a configuration diagram of a main part around the circulation of ink from an ink tank to an inkjet head in the inkjet recording apparatus of the present invention.

[Explanation of symbols]

 20, 63 Inkjet head 21 Ink tank 22 Cap 28 Ink supply tube 29, 70 Pump 38 Ink collection tube 39 Ink bypass tube 55, 56, 66, 67 Valve

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41J 2/175 B41J 2/18 B41J 2/185

Claims (11)

(57) [Claims] A recording head having an ejection port for ejecting ink onto a recording material to perform recording, an ink liquid chamber communicating with the ejection port, and an ink containing ink supplied to the ink liquid chamber. A tank, a first ink passage communicating the ink liquid chamber with the ink tank, and a second ink provided separately from the first ink passage and communicating the ink liquid chamber with the ink tank. A passage, a first pump provided in the first ink passage, for pumping ink from the ink tank to the ink liquid chamber, and a first pump provided in the second ink passage, and A second pump capable of changing the ink flow direction to either a direction toward the liquid chamber or a direction from the ink liquid chamber to the ink tank. Liquid jet recording device. 2. The ink jet recording apparatus according to claim 1, wherein said second pump is a tube pump. 3. A recording head that scans a recording material, comprising: a discharge port for discharging ink to perform recording on the recording material; and an ink liquid chamber communicating with the discharge port. An ink tank containing ink to be supplied to the ink liquid chamber; a first ink passage communicating the ink liquid chamber with the ink tank; and a first ink passage provided separately from the first ink passage, A second ink passage connecting the ink liquid chamber and the ink tank; a third ink passage connecting the first ink passage and the second ink passage; and a third ink passage provided in the first ink passage. A pump for pumping ink from the ink tank to the ink liquid chamber, a first passage opening / closing means provided in the third ink passage, for opening and closing the third ink passage, Second ink A second passage opening / closing means provided in the second ink passage between the ink tank and a connection portion between the second ink passage and the third ink passage, and opening and closing the second ink passage. An ink jet recording apparatus, wherein opening / closing by at least one of the first passage opening / closing means and the second passage opening / closing means is performed in conjunction with scanning of the recording head. 4. The ink jet recording apparatus according to claim 3, wherein said first passage opening and closing means and said second passage opening and closing means are valves. 5. The ink jet recording apparatus according to claim 1, further comprising a discharge port sealing means for sealing the discharge port. 6. The ink jet recording apparatus according to claim 1, wherein a filter for removing dust is provided in each of the first ink passage and the second ink passage. 7. The recording head according to claim 1, wherein the recording head includes an element that generates thermal energy that causes film boiling of the ink as energy used for discharging the ink.
7. The ink jet recording apparatus according to any one of items 1 to 6. 8. The ink ejection recovery method for an ink jet recording apparatus according to claim 1, wherein the ink is supplied from the ink tank to the ink liquid chamber via the first ink passage by the first pump. Supplying the ink from the ink tank to the ink liquid chamber through the second ink passage by the second pump, and discharging the ink from a discharge port of the recording head. Ink ejection recovery method. 9. The ink ejection recovery method for an ink jet recording apparatus according to claim 1, wherein the ink is supplied from the ink tank to the ink liquid chamber via the first ink passage by the first pump. And the second pump supplies ink from the ink liquid chamber to the ink tank via the second ink path, and the first ink path, the ink liquid chamber, and the second The ink in the ink passage is circulated. 10. The ink ejection recovery method for an ink jet recording apparatus according to claim 3, wherein the second passage opening / closing means is closed to shut off the flow of ink, and the first passage opening / closing means is provided. An ink ejection recovery method, wherein the ink is discharged from an ejection port of the recording head by operating the pump when the ink is opened and the ink flows. 11. The ink ejection recovery method for an ink jet recording apparatus according to claim 3, wherein the first passage opening / closing means is closed to cut off the flow of ink.
Opening the second passage opening / closing means and allowing the ink to flow, operating the pump to circulate the ink in the first ink passage, the ink liquid chamber, and the second ink passage. Characteristic ink ejection recovery method.