JP2000141695A - Liquid ejecting recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent mixing of a liquid in a channel with an impurity as well as to realize a small size of the apparatus with a smaller number of times of replenishing a liquid into a tank. SOLUTION: In a liquid ejecting recording apparatus comprising an ejecting head part having a nozzle for ejecting a liquid for recording on a medium to be recorded, a storage tank 2 comprising an air communicating opening capable of introducing the air, for temporarily storing the liquid to be supplied to the ejecting head part, a sub tank 1 comprising a sealing means for having the inside as a sealed space, for temporarily storing the liquid to be supplied to the storage tank 2 a negative pressure generating means for reducing the pressure in the sub tank 1, a first supply path for connecting the ejecting head part and the storage tank 2, and a second supply path for connecting the bottom part of the storage tank 2 and the bottom part of the sub tank 1 are provided, with the bottom surface of the sub tank 1 disposed above the bottom surface of the storage tank 2 in the vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a liquid discharge recording apparatus for supplying a large amount of ink, and more particularly to an ink jet recording apparatus.

[0002]

2. Description of the Related Art Conventionally, as a printer, a facsimile, and a copying machine of a personal computer, an ink jet recording apparatus which discharges ink droplets from a recording head to perform recording on a recording medium such as paper has been widely used.

The ink jet recording apparatus has the advantages that high quality images can be recorded with high speed and low noise, and that color images can be easily obtained.
In recent years, it has come to be used in apparatuses having a large recording volume, such as recording on a large paper size such as a poster output, and a textile printing system for printing on cloth.

Here, since the ink jet recording apparatus performs recording by discharging ink, it is necessary to constantly supply ink consumed by discharging to the recording head.

As a method of supplying ink to the recording head, in the case of an apparatus which consumes a large amount of ink as in the above-described applications, a large-capacity tank is mounted integrally with the recording apparatus main body, and a head cartridge is inserted from the tank. There is known a configuration in which an ink flow path is formed by a tube such as a tube before the ink flow.

The flexible tube used for the ink path is made of rubber or resin, so that it has some gas permeability. For this reason, air enters the tube little by little from the atmosphere through the tube wall to generate air bubbles. When these bubbles flow into the recording head, normal ink droplets cannot be ejected, and in the worst case, printing failure may occur.

Therefore, an ink circulation path as shown in FIG. 4 has been proposed so that even if bubbles are generated, the bubbles do not enter the recording head.

In FIG. 4, reference numeral 501 denotes a recording head;
2 is an air buffer chamber, and 503 is an ink tank. The air buffer chamber 502 and the ink tank 503 are connected by two ink flow paths 504 and 505 to form a circulation path. A pump 5 is provided in the ink flow path 505.
06 is provided, and the ink and air in the air buffer chamber 502 can be transferred to the ink tank 503. The air buffer chamber 502 has a closed structure with respect to the atmosphere except for two ink flow paths, and an air communication port 507 is provided in the ink tank 503.

In the above-described ink circulation path, when the pump is driven, the ink and air in the air buffer are sent to the ink tank 503 through the ink flow path 505, and
The ink in the ink tank 503 is sent to the air buffer chamber 502 through the ink flow path 504. By circulating the ink between the air buffer chamber and the ink tank in this manner, the bubbles generated in the path can be discharged to the ink tank, and the bubbles can be prevented from being mixed into the head. it can.

[0010] The applicant of the present invention has disclosed in
In Japanese Patent Application Laid-Open Publication No. H10-209, a mechanism for sending out ink is provided independently of the ink supply path in a one-way ink supply path from a main ink tank to a head via a sub-tank, so that dust in the one-way ink supply path is reduced. A liquid supply method and a liquid supply apparatus that solve the problem of removing the liquid and that easily and reliably supply the liquid in the liquid supply path.

[0011]

However, the above-described configuration has the following technical problems from the viewpoint of achieving higher gradation and higher image quality at high speed.

That is, the pump 50 is provided in the ink circulation path.
When the ink is passed through the pump, the ink passes through the inside of the pump, so that the dust generated inside the pump (for example, in the case of a tube pump, is contained in the scraps or tube material inside the tube resulting from the same portion of the tube being wrung) It has been difficult to reliably remove oil and fat components from the ink path. When these dusts adhere to the nozzles of the recording head and solidify, there is a risk of clogging. Particularly, when the discharge aperture is reduced to achieve high image quality,
Its reliable removal is required.

The present applicant has already filed an application for a recording apparatus for solving the above-mentioned problems, and the present invention
It has been recalled by a more preferred idea of the inventor.

An object of the present invention is to prevent impurities in a liquid in a passage from being mixed with the liquid, and at the same time, to achieve both miniaturization of the apparatus and reduction of the number of times of liquid supply to a tank.

[0015]

According to another aspect of the present invention, there is provided a liquid discharge recording apparatus including a discharge head having a nozzle for discharging a liquid to perform recording on a recording medium. In the ejection recording apparatus, a holding tank that temporarily holds the liquid to be supplied to the ejection head unit and has an air communication port through which the atmosphere can be introduced, and temporarily holds the liquid to be supplied to the holding tank and has an inside. A sub-tank having a sealing means for forming a closed space,
Negative pressure generating means for reducing the pressure in the sub-tank, a first supply path connecting the discharge head section and the holding tank, and a second supply path connecting the bottom of the holding tank and the bottom of the sub-tank. And a supply path, wherein the bottom surface of the sub-tank is disposed vertically above the bottom surface of the holding tank.

According to the above construction, when the holding tank and the sub-tank are connected to each other and both are opened to the atmosphere, the space not used for balancing the height of the liquid surface can be reduced to reduce the space. It is possible to achieve both reduction in the number of times of liquid supply to the tank.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described.
This will be described in detail with reference to the drawings. In the following embodiments, ink is used as the liquid. However, it goes without saying that any liquid that can be ejected from the recording head is included in the liquid of the present invention.

(First Embodiment) FIG. 1 is a schematic sectional view of a liquid supply path of a liquid discharge recording apparatus according to the present invention. 1 is a sub-tank, 2 is a holding tank, and 40 is a tank unit in which the sub-tank 1 and the holding tank 2 are unitized. The sub tank and the holding tank are connected by a second supply path. The sub-tank 1 has on-off valves 30 to 33 as sealing means for sealing the internal space.

Reference numeral 5 denotes a recording head unit in which a recording head and an air buffer chamber are integrated. The recording head unit is mounted on a carriage (not shown) and discharges ink during scanning, thereby forming a recording medium (not shown) such as paper or cloth. Record). Ink is supplied into the recording head unit by capillary action at a nozzle unit (not shown), and the ink forms a meniscus at the tip end surface (ejection port) where the nozzle unit is opened, and keeps the state filling the nozzle unit. In this state, when electricity is supplied to the electrothermal converter, the ink on the electrothermal converter is heated to generate a bubbling phenomenon, and ink droplets are ejected from the nozzles by the energy of the bubbling.

The recording head unit 5 is connected to the sub tank unit 40 by a tube 6 forming a first supply path connecting the holding tank and the air buffer chamber and a fourth supply path connecting the air buffer chamber and the sub tank. Have been. The recording head unit prevents a drop of ink from a discharge port (not shown) by providing a head difference from the liquid level of the holding tank 2 that is open to the atmosphere through the atmosphere communication port 34. Reference numeral 3 denotes a negative pressure generating means which is connected to the sub-tank and depressurizes the inside of the sub-tank, and uses a decompression pump such as a tube pump.

Reference numeral 4 denotes a replaceable main tank which stores liquid discharged from the recording head unit. The main tank is connected to the sub tank by a third supply path.

The basic liquid supply operation and circulation operation relating to FIG. 1 will be briefly described.

First, in order to supply ink from the main tank to the sub-tank, the on-off valves 30, 32 and 33 are closed.
The on-off valve 31 is opened and the pressure reducing pump is operated to replenish the liquid to the liquid level A after replenishment. Subsequently, the valve 31 is closed, and the valve 30,
When 32 is opened, both the holding tank and the sub tank are opened to the atmosphere. Accordingly, the liquid moves through the second supply path including the on-off valve 30 until the liquid level is equilibrated. From the liquid level A to the liquid level B in the sub tank, and from the liquid level C to the liquid level in the holding tank. D.

Further, in order to perform the circulation operation, the on-off valve 3
When 0, 31, and 32 are closed and the on-off valve 33 is opened to operate the pressure reducing pump, the ink is supplied into the head unit having the air buffer chamber, and the surplus ink is collected in the sub tank. Thereafter, when the valve 33 is closed and the valves 30 and 32 are opened, both the holding tank and the sub tank are opened to the atmosphere. Therefore, the liquid moves through the second supply path including the on-off valve 30 until the liquid level is balanced.

In the supply and circulation operation described above, ink can move in the supply path without passing through the pump.

When the ink is ejected from the recording head unit 5 and consumed, the ink is supplied from the holding tank and the sub-tank. When the liquid level of the holding tank reaches C, the above-described supply operation is repeated, whereby the ink in the main tank is repeated. Printing can be continued until disappears. When the ink in the main tank runs out, it can be replaced during the printing operation by displaying the ink on a display unit (not shown).

Here, in the liquid discharge recording apparatus of the present invention, in the tank unit shown in FIG. 1, the sub-tank is arranged at a position higher than the holding tank, that is, the bottom of the sub-tank is vertically above the bottom of the holding tank. In this way, the volume not used for balancing the liquid level is reduced, and the size of the tank unit is reduced.

By arranging the air communication port 3 above the sub-tank, it is possible to effectively prevent ink from leaking from the air communication port 34 when the liquid level is abnormal.

In the above-described tank unit, the time for completely equilibrating the liquid surfaces does not change as compared with the case where the bottom surfaces of the respective tanks are the same, but the difference between the liquid surfaces A and C of the respective tanks is different. The bulk of the liquid that moves to be large and equilibrium moves earlier than if the bottom of each tank were the same. Therefore, the balance operation can be considered to be completed before the complete balance is reached, and the operation can be shifted to the next operation, so that the time can be further reduced.

(Second Embodiment) FIG. 2 is a schematic sectional view of another embodiment of the sub-tank unit of the present invention.

In the present embodiment, the tank unit is integrated, and the on-off valve 30 is provided directly at the partition between the sub-tank 1 and the holding tank 2 so that the direction of ink movement by the valve 30 moves from above to below. It is. With such a structure, the size of the tank unit can be further reduced.

As described above, the principal part of the liquid discharge recording apparatus of the present invention has been described. Hereinafter, a liquid discharge recording apparatus suitable for mounting these embodiments will be described.

FIG. 3 is a perspective view showing the appearance of a color printing system which is an example of the liquid discharge recording apparatus of the present invention.

The ink jet recording apparatus main body 199 is roughly composed of an ink supply section 100 having the above-described supply path, a printer section 200, and a cloth transport section 250.

The cloth 251 as a recording medium is set on the cloth supply roller 252 in a roll state. This cloth 25
1 is transported by rollers 252 to 257 forming a transport unit 250.

The printer frame 201 located above the cloth transport section 250 has two guide rails 20.
2, 203 are supported and fixed in parallel with each other along the direction of arrow A. The carriage 204 has two guide rails 2
02 and 203 are movably supported in the direction of arrow A. A plurality of recording head units (205a and 205b are shown as representatives) are provided on the carriage at positions facing the cloth 251.

When the carriage 204 is moved in the direction of arrow A by a drive motor (not shown), for example, an ink ejection command is issued to the recording head units 205a and 205b as necessary to perform recording. At the end of the movement of the carriage 204, one line of recording is performed at a predetermined position on the cloth 251 according to the ejected ink. After one line of recording is performed on the cloth 251, the cloth 251 is conveyed by a predetermined amount in the direction of arrow B (sub-scanning direction) in FIG. 2 by a cloth feed belt (not shown). Next, for example, the recording head unit 205
When the carriage 204 moves in the direction A while the discharges a and 205b are performed as needed, a second row of recording is performed on the cloth 301. By repeating such a series of operations, desired continuous recording is performed on the cloth 301.

The recording head units 205a, 205
An ink tube group 206 is connected to 5b and the like.
Every time the ejection is repeated, the used ink is supplied from the ink supply unit 100 to the recording head units 205a and 205b via the ink tube group 206.

In each of the embodiments described above, the ink is supplied by sucking the ink from the main tank to the pressure reducing tank. However, as a configuration for achieving the object of the present invention, a configuration for supplying the ink is provided. Is not limited to this. For example, the user may directly pour ink from a bottle or the like into the decompression tank. Even in this case, it is possible to reduce the time for liquid level equilibrium associated with the above-described circulation operation.

In a liquid ejection apparatus in which generation of air bubbles is not so problematic, an air buffer chamber is eliminated and only the first supply path from the holding tank to the head is provided instead of the ink circulation path described above. Is also good.

Although the printing system has been described as an example of the recording apparatus, it is needless to say that the liquid discharge recording apparatus of the present invention is not limited to this and can be applied to a printer or the like for performing recording on recording paper. In particular, by applying the liquid supply path of the present invention, the liquid supply path can be suitably used for a printer that performs large-format printing such as poster output.

[0042]

As described above, according to the present invention,
By arranging the bottom surface of the sub tank vertically above the bottom surface of the holding tank, the volume not used for balancing the liquid level is reduced, thereby reducing the ink supply amount during communication. And the size of the entire apparatus can be reduced. In addition, the balance operation is considered to be completed before the complete equilibrium is reached, and the operation can be shifted to the next operation, so that the time can be further reduced.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing a liquid supply path of a liquid ejection recording apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a main part of a liquid supply path of a liquid ejection recording apparatus according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of the liquid ejection recording apparatus of the present invention.

FIG. 4 is an explanatory diagram illustrating an example of a conventional liquid ejection recording apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sub tank 2 Holding tank 3 Decompression pump 4 Main tank 5 Recording head unit 30, 31, 32, 33 On-off valve 34 Atmospheric communication port 40 Tank unit

Claims (6)

[Claims] 1. A liquid discharge recording apparatus comprising a discharge head unit having a nozzle for discharging a liquid to perform recording on a recording medium, wherein the liquid to be supplied to the discharge head unit is temporarily held and the air is discharged. A holding tank having an air communication port capable of being introduced, a sub-tank having a sealing means for temporarily holding a liquid to be supplied to the holding tank and making the inside a closed space, and a negative tank for depressurizing the inside of the sub-tank. A pressure supply unit, a first supply path connecting the ejection head unit and the holding tank, and a second supply path connecting a bottom of the holding tank and a bottom of the sub tank. A bottom surface of the holding tank is disposed vertically above a bottom surface of the holding tank. 2. The liquid discharge recording apparatus according to claim 1, wherein the air communication port of the holding tank is provided vertically above a liquid surface of the liquid held in the pressure reducing tank. 3. The liquid according to claim 1, wherein the holding tank and the sub-tank are integrated by a common housing and are divided by a wall provided in the housing in a horizontal direction. Discharge recording device. 4. The apparatus according to claim 1, further comprising: a main tank having a liquid to be supplied to the sub tank, and a third supply path connecting the sub tank and the main tank. The liquid ejection recording apparatus according to any one of the preceding claims. 5. The air supply chamber is provided in the head section, and the first supply path connects the air buffer and the holding tank and connects the air buffer and the sub tank with a fourth supply path. 5. The liquid ejection recording apparatus according to claim 1, further comprising a path. 6. The discharge head section includes an electrothermal conversion element for generating thermal energy for liquid discharge, and discharges the liquid by causing film boiling by the heat energy applied by the electrothermal conversion element. The liquid ejection recording apparatus according to claim 1, wherein the recording is performed.