JPH0911496A - Ink jet recorder and ink discharge recovering method therefor - Google Patents

Abstract

PURPOSE: To enable the discharge ink amount to be reduced and to stabilize the discharge capable of shortening the operating time of a pump by providing a means for simultaneously pressurizing ink from at least two ink channels for communicating an ink tank with an ink liquid chamber for communicating the tank with the discharge port of a recording head. CONSTITUTION: If the channel resistance from an ink bypass tube 39 to a liquid chamber through an ink recovery tube 38 is the same as that of the tube 28 of a liquid chamber side 45 from the connecting part with the tube 38 when the thickened ink or bubble in a liquid passage 47 communicating from a common liquid chamber 45 to discharge ports is removed, the ink amount introduced from the tube 28 becomes the same as that introduced from the tube 38 to the chamber 45 via the tube 39. Since the ink is pressurized and introduced by the same pressure from both the ends of the chamber 45 in this state, the ink pressures in the chamber 45 and the passage 47 communicating with the discharge become equivalent, the inks of the same amounts are discharged from the channels of the discharge ports, and the thickened ink or bubble is urged out of the nozzle. This is conducted at the time of turning ON a power source.

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 ink is directly ejected from an ejection port of a recording head to perform recording, it is necessary to always maintain a state in which ink can be ejected, and therefore special consideration is required. .

That is, since the ink remains in the liquid passage in the recording head even during non-recording, it is necessary to take measures to prevent deterioration such as viscosity increase due to drying or evaporation of the ink in the liquid passage. In addition, a capping unit is used to prevent the ink from drying or evaporating by covering the ejection port forming surface (face surface) of the recording head with a cap (lid) at the time of non-recording.

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

Therefore, a pump or the like together with the capping means applies pressure to the liquid passage in the recording head, or, conversely, sucks air in the cap to give a negative pressure to the liquid passage. A recovery mechanism has been used in which ink that has stagnated and deteriorated in the liquid passage is discharged from the ejection port.

In addition, the ink cartridge can be replaced,
When the recording apparatus is stopped for a long period of time, bubbles may stay in the recording head (for example, the common liquid chamber) or other ink flow paths. Ejection failure such as complete ejection will occur.

Therefore, the ink is supplied from the ink tank to the recording head through the ink supply passage by a pump or the like, and the ink is ejected from the ejection port with the cap on the face surface (in the capping state). Ink that has increased viscosity in the vicinity of the ejection port (thickened ink) is discharged by circulating the remaining ink into the ink tank from the recovery flow path while treating it as waste ink while discharging it to the inside. Bubbles in the ink flow path are collected together with ink in an ink tank.

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

Further, although 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 to adhere the ink. There is also used a removing means (head cleaning means) for wiping off or removing the adhered ink by ejecting air from an air nozzle.

[0010]

However, in the case of the above-mentioned prior art, when ejecting the ink in the vicinity of the thickened ejection port as the ejected ink, the ink in the vicinity of the ejection port is ejected while circulating the ink. Since the cross-sectional area of the outlet is very small, the flow path resistance is very large. However, the flow path resistance of the ink discharge flow path is smaller than that. Therefore, the amount of ink that circulates in the ink recovery flow path becomes extremely larger than the amount of ink that is discharged from the ejection port.

Therefore, in order to discharge the thickened ink from the ejection port, it is necessary to circulate a much larger amount of ink than the ink ejected from the ejection 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, and therefore, in a portion near the ink supply passage and a portion far from the ink supply passage (a portion near the ink recovery passage). , The pressure applied to the ink is different. That is, a large pressure is applied to the ink in the portion near the ink supply passage, but the pressure is small in the portion far from the ink supply passage (the portion near the ink recovery passage).

Therefore, a large amount of ink is ejected at the ejection port near the ink supply channel, and is ejected at the ejection port far from the ink supply channel, that is, at the ejection port near the ink recovery channel. The amount of ink ejected is reduced.

Therefore, when the pump is operated to discharge the amount of ink necessary to completely discharge the thickened ink at the ejection port on the side far from the ink supply flow path, the ink on the side close to the ink supply flow path is discharged. There is also a problem that an excessive amount of discharged ink is discharged from the ejection port, 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 and the recording width of the head was widened, this tendency was remarkable.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and the purpose thereof is to reduce the amount of ink discharged from the discharge port and shorten the operating time of the pump. An object of the present invention is to provide a small-sized, inexpensive, quiet, highly reliable inkjet recording device with stable ink ejection.

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

[0017]

SUMMARY OF THE INVENTION The present invention is an ink jet recording apparatus for recording by ejecting ink from a discharge port of a recording head onto a recording material, and an ink liquid communicating with the ink tank and the discharge port of the recording head. An ink jet recording apparatus comprising at least two ink flow paths communicating with a chamber, and means for simultaneously pressurizing ink to the ink liquid chamber from both the ink flow paths are provided. .

The ink jet recording apparatus of the present invention is
Preferably, a pump for pumping ink from the ink tank to the ink liquid chamber is provided in one of the two ink flow paths (first ink path), and the first ink between the pump and the ink tank is provided. The passage and the other ink passage (second ink passage) are connected by the third ink passage, and the second ink between the connecting portion of the second ink passage and the third ink passage and the ink tank A flow path opening / closing means (second flow path opening / closing means) for controlling opening / closing of the flow path is provided in the flow path, and another flow path opening / closing means (first flow path opening / closing means) is provided in the third ink path.
The inkjet recording apparatus is provided with.

Further, the above-mentioned ink jet recording apparatus of the present invention may be provided with a discharge port sealing means for sealing the discharge port, and the second ink passage extending from the connecting portion with the third ink passage to the ink tank. An ink pump that applies a negative pressure to the ink liquid chamber may be provided.

Further, in the above-mentioned ink jet recording apparatus of the present invention, dust removing filters are provided in the first ink passage and the second ink passage on the ink liquid chamber side of the connection portion with the third ink passage, respectively. Is it
Alternatively, a filter for removing dust may be provided in each of the first ink passage and the second ink passage on the ink tank side of the connection portion with the third ink passage.

Further, in the ink jet recording apparatus of the present invention, at least one of the flow path opening / closing means may be opened / closed in association with the position of the recording head.

Further, according to the present invention, in the above-mentioned ink jet recording apparatus, the second flow path opening / closing means is closed to interrupt the flow of ink, and the first flow path opening / closing means is opened so that ink flows. Provided is an ink discharge recovery method of operating an ink pump to discharge ink from a discharge port of a recording head.

Further, according to the present invention, in the above-mentioned ink jet recording apparatus, the first flow path opening / closing means is closed to interrupt the flow of ink, and the second flow path opening / closing means is opened so that ink flows. Provided is an ink discharge recovery method for operating an ink pump to circulate ink in a first ink passage, an ink liquid chamber in a recording head, and a second ink passage.

[0024]

【Example】

(Example 1) An example of an ink jet recording apparatus to which the present invention is applied will be described below 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 embodying the present invention, and FIG. 2 is a perspective view showing a constitution of an ink jet head and an ink passage of such an ink jet recording apparatus. It is a figure. 3 is a sectional perspective view of the cap in FIG. 1, and FIG. 4 is FIG.
It is a cross-sectional view of the cap of. 5 to 10 are schematic side views showing the operations of the inkjet head and the cap. 11 and 12 are schematic diagrams of the ink jet head, the ink passages, and the valves showing the flow of ink in the vicinity of the ink jet head.

As shown in FIG. 1, the recording material 2 loaded in the cassette 1 detachably provided in the ink jet recording apparatus is fed one by one by the rotation of the feeding roller 3, and the recording material 2 is fed by the motor. A sheet feeding system motor driven by the driver 34 rotates the feeding roller pair 5 to convey the recording material to the recording material conveying system 4.

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

Recording material 2 conveyed to recording material conveying system 4
The leading end hits a nip portion formed by the pinch roller 13A and the endless transport belt 7 and is flexibly held in a loop shape along the transport guide 6, thereby performing a registration operation for aligning the leading end in a direction orthogonal to the transport direction.

Thereafter, the recording material 2 is charged by the charger driver 3
A potential difference is generated between the conveyor belt 7 which is charged by the charger 12 driven by 3 and is discharged, and the belt conveyor roller 10 is connected by the pressure contact effect of the pinch rollers 13A and 13B and the electrostatic adsorption effect due to the potential difference. It is conveyed in the direction of the arrow X in a state in which it is firmly attached to the conveyance belt 7 driven by the driven motor 11.

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

The ink jet recording apparatus can record a high-definition image at a high speed, and since it is a non-impact system, it produces less noise, and it is easy to record a color image using multicolor inks. There are some advantages.

The recording head in the ink jet recording system has a liquid ejection port for ejecting and ejecting a recording ink liquid as flying droplets, a liquid channel communicating with the ejection port, and a part of the liquid channel. Ejection energy generating means is provided which gives ejection energy for ejecting the ink liquid in the flow path. Then, the ejection energy generating means is driven according to the image signal to eject ink droplets to generate an image.

As the discharge energy generating means, for example, a method of using pressure energy generating means such as an electromechanical transducer such as a piezo element, or electromagnetic energy for radiating and absorbing electromagnetic waves such as laser into ink liquid to generate flying droplets is used. There is a method using a generating means, a method using an energy generating means for heating the liquid by an electrothermal converter such as a heating element having a heating resistor to eject the liquid.

Among them, the recording head used in the ink jet recording system for ejecting liquid by thermal energy has liquid ejection ports for ejecting recording liquid droplets to form ejected solution droplets arranged at high density. Therefore, it is possible to record with high resolution.

Further, among them, the recording head used as the heat energy generating means of the electrothermal converter can be easily made compact, and the IC technology and the micro-technology which have been remarkably improved in the technological progress and reliability in the recent semiconductor field. This is advantageous because the advantages of processing can be fully utilized, high-density mounting is easy, and the manufacturing cost is low.

In FIG. 2, the ink jet head 20 is shown.
On top of the aluminum head base 41 of
4 and the silicon substrate 42 are bonded to each other, and the resin cover 43 is bonded to the upper surface of the silicon substrate 42.

A heating element (not shown) for generating ejection energy is provided at the portion of each liquid passage 47 of the silicon substrate 42.
Are arranged.

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

In the resin cover 43, an ink common liquid chamber 45 and a liquid passage 47 leading to each ejection port 46 are formed, and when the resin cover 43 is brought into close contact with the silicon substrate 42, the ink common liquid chamber 45 and each A liquid path 47 leading to the discharge port is formed.

Further, since the silicon substrate 42 is very expensive, it is necessary to make the area as small as possible to reduce the cost. For this reason, it leads to 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 to reduce the contact area of the resin cover 43 with the silicon substrate 42.

Therefore, the flow path resistance in the common liquid chamber 45 is higher than that of 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.
An ink recovery passage (tube) 38, which is a second ink passage, is connected to the other end of the common liquid chamber 45. A filter 49 composed of a metal mesh is provided at this connection portion, and dust or the like is common when the ink jet head 20 is attached to the apparatus or when the ink supply tube 28 or the ink discharge tube 38 is removed. It does not interfere with the flow of ink by entering the liquid chamber 45 and the liquid path 47 leading to each ejection port.

The ink supply tube 28 and the ink recovery tube 38 are connected by an ink bypass tube 39 which is a third ink passage, and a first solenoid valve as a flow path opening / closing means is provided in the middle of the ink bypass tube 39. 5
6 is provided so that the opening and closing of the passage can be controlled.

A second electromagnetic valve 55 as a flow passage opening / closing means is provided in the ink discharge tube 38A portion closer to the ink tank than the connecting portion between the ink recovery tube 38 and the ink bypass tube 39, and the passage is opened and closed in the same manner. 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 construction of the ink jet head 20 described with reference to FIG. It will be implemented in the same manner as above.

The ink tanks 21 are each head unit 20.
Four tanks 21A, 21B, 21C and 21 for supplying ink of colors corresponding to A, 20B, 20C and 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 provided with four ink jet heads 20A to 20D and four ink tanks 21A to 21D, respectively. 21D corresponding to four ink supply passages (tubes) 28A, 28B, 28C, 28D;
Four ink recovery passages (tubes) 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 water heads in the tanks 21A to 21D are kept lower than the ejection port forming surface (face surface) 48 of each head unit 20A to 20D by a predetermined height, and the ink ejected at the time of recording is capillarity of the ink flow path. Is used to supply each head unit 20.

Further, each ink tank 21A, 21B, 2
1C and 21D are provided with about 20% of the initial volume of the air pool and holes (vent holes) for circulating the air.

Four inkjet heads 20A, 20
Holders B, 20C, and 20D are arranged so that the intervals (pitch) of the ejection ports 46 with respect to the recording material conveyance direction are constant.
The head unit 24, which is configured to be fixed by 3, can be moved up and down by the head moving means 25.

The cap 2 capped on the ejection port forming surface (face surface) 48 of the ink jet head 20 at the time of non-recording.
2 can be moved by the cap moving means 26 in the recording material conveyance direction (X direction) and in the opposite direction.

The cap 22 includes the four ink jet heads (heads 20A, 20B, 20C, 2).
0D) corresponding to the four caps 22A, 22B, 2
It is composed of 2C and 22D.

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

These caps are the head unit 20.
The heads 20A to 20D are arranged at the same intervals as A, 20B, 20C, and 20D, and are fixedly supported so that the head units 20A to 20D can be simultaneously crowned. In addition, each cap 22
As shown in FIGS. 3 and 4, it is formed of a hollow body, and an opening 51 for opening the ejection port 46 of the face surface 48 of each head unit (ink jet head) 20 into the cap is formed in the center of the upper surface. Is formed, and a sponge-like ink absorbing member 52 for holding ink to be ejected (idle ejection) from the ejection port 46 is housed inside.

The ink in the ink tank 21 can be supplied to the common liquid chamber 45 inside 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 unit) 20 is
It is closely attached to the cap 22 and prevents the ink from evaporating from each ejection port 46.

When the power is turned on from this state, first, the head unit 24 (ink jet 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 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 conveying direction) in FIGS. 3 and 4. 7 to cover the length of the ejection port array on the face surface, which is joined to a position (the edge portion in the illustrated example) off the opening on the upper surface of the cap, as shown in FIG. The sealing member 53 and the discharge port 46 are set so as to match each other.

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

Next, the ink jet head 20 is pushed down and the sealing member 53 is brought into pressure contact with the ejection port array, whereby 1
After sealing all the discharge ports of the line to the state of FIG. 8, the first solenoid valve 5 provided in the ink bypass tube 39
6 is closed, the second electromagnetic valve 55 provided in the ink discharge tube 38 is opened, and the ink pump 29 is operated in this state, and as shown by the arrow in FIG. 11, the ink tank 21 → ink pump 29 → ink supply tube. 28 → common liquid chamber 4
The ink is circulated in the order of 5 → ink recovery tube 38 → second electromagnetic valve 55 → ink recovery tube 38 → ink tank 21.

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

This ink circulation operation is performed not only for removing the bubbles in the common liquid chamber but also when the ink and the ink jet head are heated up due to the thermal energy generated at the time of recording and ejection failure occurs. It is also possible to cool the head.

When removing the thickened ink and bubbles in the liquid passage 47 leading from the common liquid chamber 45 to each ejection port, the first solenoid valve provided in the ink bypass tube 39 in the state shown in FIG. 56 is opened and the ink recovery tube 3
The second electromagnetic valve 55 provided in 8 is closed, and the ink pump 21 is operated in this state, and the 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 chamber 45 and the ink tank 21 → the ink pump 29 → the ink supply tube 28 → the ink bypass tube 39 → the first electromagnetic valve 56 → the ink recovery tube 38 → the common liquid chamber 45 are supplied in the order.

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 side 45 from the connection portion with the ink bypass tube 38. If the resistances are the same, the amount of ink entering from the ink supply tube 28 is the same as the amount of ink entering the common liquid chamber 45 from the ink recovery tube 38 through the ink bypass tube 39. In this state, the ink pressurizes and flows 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 ejection ports become substantially equal, and the ink is ejected. The same amount of ink is discharged from the flow path to the outlet,
Push the thickened ink and bubbles out of the nozzle.

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

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

Thereafter, the cap moving means 26 moves the cap 22 in the direction opposite to the X direction so that the cap 22 is retracted from the ink jet head 29 as shown in FIG.
So that it can fit in.

Then, the ink jet head 29 is lowered by the head moving means 25 and set at the position where the distance between the face surface 48 and the surface of the conveyor belt 7 is about 1 mm, that is, 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 the paper feed cassette 1
2 are picked up one by one and guided between a pair of feeding rollers 5, and the leading end of the recording material 2 is constituted by a pair of feeding rollers 5 and an endless conveyor belt 7 pressed against an idle roller 8 and a pinch roller 13A. The recording material 2 is further fed from that state, a loop is formed in the space of the chevron-shaped conveyance guide 6, and the entire tip portion of the recording material 2 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 secured.

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 conveyor belt 7 by the pinch roller 13A.

In the charger 12, the upper side of the conveyor belt 7 is +,
The lower side has a negative sign, and a potential difference is generated between the recording material 2 and the conveyor belt 7 that is neutralized immediately before the pinch roller 13A, and the recording material 2 is attracted to the conveyor belt 7 by electrostatic force.

In this case, due to the pressure contact of the pinch roller 13B after passing through the charger 12, the adsorption of the recording material 2 on the surface of the conveyor belt 7 becomes even more reliable.

In this way, the recording material 2 is conveyed,
Recording is performed by ejecting ink from the inkjet head 20 after the leading edge of the recording material 2 reaches the inkjet head 20 while counting the conveyance of the recording material 2 in synchronization with the activation of the belt motor 11. When a plurality of inkjet heads are used, recording of each color is sequentially performed after the tip of the recording material 2 reaches each inkjet head.

The recording material 2 for which recording has been completed is curvature-separated from the rear end of the conveyor belt 7 and is ejected to the paper ejection tray 15.

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

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

When recording is completed, the head unit 24
After the (ink jet head 20) is moved up by the head moving means 25 to the state of FIG. 9, the cap moving means 26 moves the cap unit 22 in the X direction by a predetermined amount to return to the state of FIG. 6, and then the head unit. 24
Is pushed down to bring the cap 22 onto the face surface 45 of each inkjet head as shown in FIG.

In this capping state, all of the discharge ports 46 arranged in a line form the openings 51 of the cap 22.
Through to the space inside the cap 22.

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

The ink consumed by the ejection at the time of recording is supplied from either the ink supply tube 28 or the ink recovery tube 38, or both of them. When the ink is recovered from the ink recovery tube 38, the first electromagnetic wave is supplied. Either the valve 56 or the second electromagnetic valve 55 or both of them are opened by a capillary phenomenon in the inkjet head 20.

In the above embodiment, the belt 7 and the electrostatic adsorption means 12 are used as the conveying means for the recording material 2. However, instead of this, other methods such as air adsorption by the belt or a system using a drum are used. Schemes can also be used and similar effects can be achieved.

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

Further, in this embodiment, in the ink supply tube 28 which is the first ink passage and the ink recovery tube 38 which is the second ink passage, the joint portion between the ink bypass tube 39 which is the third ink passage. A filter 49 for removing dust is provided on the common liquid chamber side of the first ink passage and a part of the second ink passage when the inkjet head is manufactured or assembled or replaced. When the third ink passage can be treated integrally with the ink jet head, the common liquid is applied to the ink tank side rather than the joint between the first and second ink passages and the third ink passage, that is, the joint. It is also possible to place filters on opposite sides of the chamber.

(Embodiment 2) Embodiment 2 of the present invention will be described with reference to FIGS.
This will be described with reference to FIG.

FIG. 13 is a sectional view of a main portion of a recording portion of an ink jet recording apparatus embodying the present invention, and FIG.
FIG. 3 is a perspective view of a head carriage unit equipped with an inkjet head of an inkjet recording apparatus embodying the present invention. 15 and 16 are cross-sectional views of the main part of the recording part when the recording part is viewed from the recording paper conveyance direction in order to explain the state during the recovery operation.

The configuration of the entire apparatus in this embodiment is almost the same as that described in the first embodiment, and the same parts are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the ink jet head 63 is used.
Is provided on the head carriage 64, and performs image recording by a so-called serial scan method in which recording is performed by scanning the head carriage 64. The ink supply tube 28, the ink recovery tube 38, and the bypass tube 39 are made of plastic. The bypass tube 39 and the ink recovery tube 38 are made of a material (for example, silicon).
Valves 66 and 67 for restricting the flow of ink by crushing the tube are provided at the same position as in the first embodiment, and the valves are turned on / off by moving the carriage.

Recording material 2 fed and conveyed from the cassette
Is conveyed to a recording position on the platen 62 by a pair of conveying rollers 60 and 61.

In this state, the head carriage 64 on which the ink jet head 63 is mounted is orthogonal to the direction in which the recording material is conveyed (direction orthogonal to the paper surface in FIG. 13, arrow Y direction in FIGS. 14 to 16). To rail 65
The recording material 2 is scanned along with the ink to be ejected onto the recording material 2 for recording.

After that, 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 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 as in the first embodiment, and the ink circulated through the ink recovery tube 38 is supplied to the ink tank. It is configured to return to 21.

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, so that a tube made of a flexible material prevents the head carriage 64 from scanning. In order not to exist, it is arranged in a U shape as shown in FIGS. 15 and 16 so as to be along the scanning direction (Y direction) of the head carriage.

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

When the ink is circulated in the common liquid chamber 45, first, the head carriage 64 is located at a position where the ejection port 46 on the face surface of the ink jet head 63 shown in FIG. 15 faces the sealing member 53 provided on the cap 22. 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 sloped surface 66b provided on the apparatus body, and the flow of ink is stopped. Let Then, in the state of FIG. 15, the cap 22 is moved in the head direction (Z direction) by the cap driving means (not shown), and the sealing member 53 is brought into pressure contact with the ejection port array to seal all the ejection ports of one line.

In this state, the first valve 66 shown in FIG.
Shows that the ink bypass tube 39 is crushed by the first sealing member 66a.
The second valve 67 provided in the eighth portion is not in a state in which the second sealing member 67a crushes the ink recovery tube 38 due to the second inclined surface 67b provided in the apparatus main body.

Here, the ink pump 29 is operated, and the ink tank 21 → the ink pump 29 → the same as in the first embodiment.
The ink is circulated in the order of the ink supply tube 28 → the common liquid chamber 45 → the ink recovery tube 38 → the ink tank 21.

After the above ink circulation is performed at a predetermined flow rate for a predetermined time, the cap 22 is retracted, and then the head carriage 64 is moved to the ejection port array 2 as shown in FIG.
2 to a position facing the opening of the cap 2,
Is moved in the direction (Z direction) to be pressed against the inkjet head 63, and is returned to the position of the cap set of FIG.

In the state of FIG. 16, the second valve 6
The sealing member 67a that constitutes No. 7 crushes the ink discharge tube 38 by the second slope 67b provided on the apparatus main body to stop the flow of ink. The first valve 66 does not hinder the ink flow in the ink bypass tube 39 because the first sealing member 66a passes through the slope 66b.

Liquid path 4 from the common liquid chamber 45 to each discharge port
In order to remove the thickened ink and air bubbles in 7, the ink pump 21 is operated in the state of FIG. 15 (FIG. 6),
As shown by the arrow in FIG. 12 in Example 1, the ink is
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 4
Supply in the order of 5.

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 resistances are the same, the amount of ink entering from the ink supply tube 28 is the same as the amount of ink entering the common liquid chamber 45 from the ink recovery tube 38 through the ink bypass tube 39. In this state, the ink pressurizes and flows from both ends of the common liquid chamber 45 at 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 become substantially equal, and the respective discharge ports become uniform. The same amount of ink is pushed out of the flow path to the nozzle, and the thickened ink and bubbles are pushed out of the nozzle.

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

In both the first and second embodiments, when the ink is circulated in the common liquid chamber, the ejection port array is sealed by the sealing member, the ink is supplied by the pump, and the ink is discharged from the ink recovery tube. However, a pump is also provided in the middle of the ink recovery 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 recovery tube are operated at the same time. It is also possible to circulate the ink in the common liquid chamber by making the amount of ink sent to the common liquid chamber and the amount of ink that is forcibly recovered from the ink recovery tube by the pump from the common liquid chamber almost the same. is there.

Furthermore, 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, the common liquid chamber It becomes possible to simultaneously circulate the ink and push out the thickened ink and bubbles in the flow path to each ejection port to the outside of the nozzle.

(Third Embodiment) A third embodiment will be described with reference to FIG.

FIG. 17 is a block diagram of the main part around the circulation of the ink from the ink tank to the ink jet head in this embodiment. Other recording paper transporting mechanisms and operations are those described in the first embodiment. The same parts are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the first pump for pressurizing the ink to the common liquid chamber between the ink supply tube and the ink tank, and the common pump for pressurizing the ink to the common liquid chamber between the ink recovery tube and the ink tank A second pump that can apply a negative pressure to the ink in the liquid chamber is provided.

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. A so-called tube pump is used to send ink by causing a volume change in the tube to change the pressure, and by changing the rotation direction of the roller, the ink sending direction is changed.

When the ink in the common liquid chamber 45 is circulated, 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 second ink is supplied. 17, a roller holder 72 that holds a roller 71 that constitutes the ink pump 70 is rotated in the direction of arrow C in FIG. 17, and the ink recovery tube 38 is rotated while being crushed by the roller 71 and the tube holding portion 73 to cause a volume change. , 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, it becomes possible to circulate the ink in the common liquid chamber of the inkjet head 20.

A roller 71 is provided in the ink recovery 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 leaves the tube, a pulsation reduction tank 74 that holds air in a sealed state and obtains a damping effect is provided.

Further, when removing the thickened ink and bubbles in the liquid passage 47 (FIG. 2) communicating from the common liquid chamber 45 to each ejection port, the ink is supplied from the ink supply tube 28 by the first ink pump 29 in common. In the liquid chamber 45 (direction of arrow A)
By supplying 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 recovery tube 38, and the ink is discharged from the ink tank 21 into the common liquid chamber 45. The same effect as in Examples 1 and 2 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 ink circulation, the ink circulation and the discharge of the thickened ink in the liquid passage are simultaneously performed. It is also possible to control the emission amount.

[0112]

As described above, according to the present invention, it is possible to reduce the amount of ink discharged from the discharge port and shorten the operation time of the pump, which is small, inexpensive, quiet, and has stable and stable ink discharge. A reliable inkjet recording apparatus can be obtained, and a highly efficient ejection recovery method for an 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 inkjet recording apparatus of the present invention.

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

FIG. 3 is a sectional perspective view of an example of a cap of the inkjet recording apparatus of the present invention.

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

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

FIG. 7 is a schematic cross-sectional view showing a state in which the positions of the ejection port and the sealing member separated by a predetermined distance are the same in the operation of the cap of the inkjet recording apparatus of the present invention.

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

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

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

FIG. 12 is a schematic diagram showing 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 cross-sectional view of main parts of a recording unit of the inkjet recording apparatus of the present invention.

FIG. 14 is a perspective view of a head carriage unit equipped with an inkjet head of an inkjet recording apparatus of the present invention.

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

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

FIG. 17 is a configuration diagram of main parts 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 recovery tube 39 Ink bypass tube 55, 56, 66, 67 valve

Claims (11)

[Claims] 1. In an inkjet recording apparatus for recording by ejecting ink from a discharge port of a recording head onto a recording material, at least two ink tanks are connected to an ink liquid chamber communicating with the discharge port of the recording head. 2. An ink jet recording apparatus, comprising: the ink flow path of, and a means for simultaneously pressurizing ink to the ink liquid chamber from both of the ink flow paths. 2. A pump for pumping ink from the ink tank to the ink liquid chamber is provided in one of the two ink flow paths (first ink passage), and a first pump between the pump and the ink tank is provided. Of the second ink passage and the other ink passage (the second ink passage) are connected by the third ink passage, and the second portion between the ink tank and the connecting portion of the second ink passage and the third ink passage. A channel opening / closing unit (second channel opening / closing unit) for controlling opening / closing of the ink channel is provided in the second ink channel, and another channel opening / closing unit (first channel opening / closing unit) is provided in the third ink channel. ) Is provided, the inkjet recording device according to claim 1. 3. The ink jet recording apparatus according to claim 1, wherein the flow path opening / closing means is a valve. 4. The ink jet recording apparatus according to claim 1, further comprising discharge port sealing means for sealing the discharge port. 5. The ink pump for applying a negative pressure to the ink liquid chamber is provided in the second ink passage extending from the connecting portion with the third ink passage to the ink tank. Inkjet recording device. 6. The filter for removing dust is provided in each of the first ink passage and the second ink passage on the ink liquid chamber side of the connection portion with the third ink passage. The ink jet recording apparatus according to any one of claims. 7. A dust removing filter is provided in each of the first ink passage and the second ink passage on the ink tank side of the connection portion with the third ink passage. An inkjet recording device according to claim 1. 8. The ink jet recording apparatus according to claim 1, wherein the recording head has an element that generates thermal energy that causes film boiling of the ink as energy used for ejecting ink. . 9. The opening / closing of at least one of the flow path opening / closing means is interlocked with the position of a recording head.
9. The inkjet recording device according to any one of 8 to 8. 10. The ink jet recording apparatus according to claim 1, wherein the second flow path opening / closing means is closed to interrupt the flow of ink and the first flow path opening / closing means is opened. The ink discharge recovery method in which the ink pump is activated to discharge the ink from the discharge port of the recording head. 11. The ink jet recording apparatus according to claim 1, wherein the first flow path opening / closing means is closed to interrupt the flow of ink and the second flow path opening / closing means is opened. And a state in which the ink flows, an ink discharge recovery method in which the ink pump is operated to circulate the ink in the first ink passage, the ink liquid chamber in the recording head, and the second ink passage.