JP2002240315A - Ink jet printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink jet printer in which the liquid level can be adjusted upward to a constant level at all times without requiring a structure influencing ink supply, by sucking a large volume of air from the air part above the liquid level in an air buffer container lowered due to mixture of bubbles while suppressing variation of liquid level even in a color ink jet printer using multiple color inks, and to provide a mechanism for coupling a carriage with an ink storage tank can be simplified regardless of ink supply. SOLUTION: An air buffer container 1 comprises a first ink chamber 2 on the side of an opening 5 for sucking ink from an ink storage tank 13, and a second ink chamber 3 on the side of a recording head 10. The first ink chamber 2 is provided with a first interconnection opening 7 for supplying ink to the second ink chamber 3 when the first ink chamber 2 is filled with a specified quantity of ink or more, and a second interconnection opening 8 provided with an opening/closing means for interconnecting the first and second ink chambers 2 and 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet printer provided with an ink supply device for supplying ink to a recording head used in an ink jet recording device.

[0002]

2. Description of the Related Art Conventionally, in an ink jet recording apparatus for printing by reciprocating a recording head mounted on a carriage, it is necessary to increase the capacity of the ink storage tank in order to reduce the frequency of replacing the ink storage tank. If the recording head is integrated to increase the capacity, the inertia of the ink storage tank mounted on the carriage will increase, so the ink storage tank is arranged at a position where it does not move, and the recording head on the carriage has a supply tube etc. The objective has been sought to achieve this goal by connecting to various pumps.

However, in an ink jet recording apparatus, a slight negative pressure is always applied to the atmospheric pressure so as to prevent the recording ink from dripping except at the time of printing driving from a recording head, thereby achieving both ejection and prevention of unnecessary dripping. When reciprocation of printing is applied, the recording ink in the supply tube also flows and pushes out or pulls out the recording ink in the recording head, causing a change in the discharge amount to cause printing unevenness and non-discharge.

As a countermeasure, an air reservoir is provided near the recording head between the supply tube and the recording head. There is known a technique of arranging an air buffer container that stabilizes ejection by buffering pressure fluctuations caused by ink flow in a supply tube by utilizing air elasticity.

[0005] This air buffer container has an upper portion as an air reservoir and a lower portion as an ink reservoir, and also has a function of separating air from ink in a supply tube containing air and sending only ink to a recording head. It is necessary to ensure a required liquid level of the ink reservoir so that air does not enter the recording head from the air reservoir due to the fluctuation of the liquid surface of the ink reservoir due to the reciprocation of the carriage.

For the purpose of air separation, there is also a method of transporting and printing a recording medium without scanning a carriage, in which a similar container is provided for separating mixed air. Also, it is necessary to secure the required liquid level of the internal ink reservoir.

However, if the ink jet printer is in a state of printing or standing for a long period of time, air bubbles accumulate due to the permeation of air from the supply tube wall or the generation of dissolved ink, and the air bubbles reach the air buffer container by the printing and recording operation. And the liquid level in the air buffer container gradually decreases, and eventually ink runs out in the air buffer container, resulting in poor printing.

As described above, since the liquid level tends to gradually decrease due to air permeation from the supply tube wall and degassing of the dissolved gas, the required liquid level is maintained continuously. To do so, connect one end of each of the two tubes to the bottom of the ink reservoir and the desired liquid level,
A method in which the other end is connected to another tank and circulated by a pump or the like, or a single supply tube can be used to reduce the ink inflow resistance of the suction port of the air buffer container by disposing a filter member or significantly restricting the inner diameter. By restricting the inner diameter of the supply tube to be connected, the pressure can be set to be equal to or higher than the air outflow resistance of the nozzle portion of the recording head, or the ink supply path can be provided with an opening / closing means to control the reduced pressure in the air buffer container. Then, there is a method of returning to the required liquid level.

[0009]

However, this 2
In the method of maintaining the liquid level using the tubes, the number of tubes connected between the scanning carriage and the ink storage tank that does not move is doubled, and in the case of a color printer using multi-color inks, the effects of tube routing and the increase in rigidity, disadvantages in member assembly costs, etc. are disadvantageous.

[0010] In addition, the liquid level returning method by limiting the ink inflow resistance in a single supply tube is difficult to adapt to monochrome high-speed printing or the like that requires a large amount of ink supply, and a method of controlling the reduced pressure amount. In this case, the liquid level height varies due to variations in the amount of reduced pressure in the air buffer container. In particular, in a color printer using multi-color ink, a pressure difference occurs in the air buffer container of each color, and it is difficult to maintain a uniform liquid level.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described aspects, and an object thereof is to provide an air buffer container including a first ink chamber on an ink suction port side of an ink storage tank and a recording head. And a first communication port through which ink flows to the second ink chamber when the first ink chamber is filled with a predetermined amount or more of ink, and the first and the second ink chambers. By providing a second communication port provided with an opening / closing means for communicating the second ink chamber, it is possible to use a multi-color ink without taking a structure that affects the ink supply amount such as increasing the ink inflow resistance. Even in the inkjet printer, the variation in the liquid level due to the variation in decompression is suppressed, and air can be sucked in from the upper air part where the liquid level in the air buffer container has dropped due to the incorporation of bubbles, Always It is an object of the present invention to provide an ink jet printer that can raise and lower the liquid level to a certain height and can simplify the connection-related mechanism between the carriage and the ink storage tank regardless of the ink supply amount. .

[0012]

Therefore, the present invention aims at achieving the above object by providing an ink jet printer described in any of the following items (1) to (6). is there.

(1) Means for recording by scanning the recording head or transporting the recording medium and changing the relative position between the recording medium and the recording head, and not affected by scanning of the recording head or transport of the recording medium An ink storage tank disposed in a portion, an air buffer container configured in a print head, and an ink jet printing apparatus including a unit that supplies recording ink to the print head via the air buffer container from the ink storage tank, The air buffer container includes a first ink chamber on the ink suction port side from the ink storage tank and a second ink chamber on the recording head side, and the first ink chamber is filled with a predetermined amount or more of ink. In the case, a first communication port through which ink flows to the second ink chamber, and a second communication port provided with an opening / closing means for communicating the first and second ink chambers are provided. Jet printer, characterized in that.

(2) The ink jet printer according to item (1), wherein the first communication port is located at a position higher than the second communication port.

(3) The ink jet printer according to the above item (1) or (2), wherein the opening / closing means is mounted on a carriage.

(4) The ink jet printer according to any one of (1) to (3), wherein the opening / closing means uses a drive source of a head recovery device.

(5) The ink jet printer according to any one of (1) to (3), wherein the opening / closing means is a float valve having a specific gravity lower than that of ink.

(6) The recording head is provided with an electrothermal converter for generating thermal energy for discharging the recording ink, and utilizes the film boiling generated by the ink by the thermal energy applied by the electrothermal heater. The inkjet printer according to any one of the above items (1) to (5), wherein the inkjet head is a recording head having a structure for ejecting recording ink from an ejection port.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an ink jet printer according to the present invention will be specifically described below with reference to the drawings.

(First Embodiment) FIG. 1 is a schematic sectional view of an ink jet printer showing a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes an air buffer container, 2 denotes a first ink chamber, and 3 denotes a second ink chamber. 4 is an inner wall, 5 is an ink suction port, 6 is a filter, 7
Is a first communication port through which ink flows into the second ink chamber when the first ink chamber 2 is filled with a predetermined amount or more of ink;
Is a second communication port provided with an opening / closing means for communicating the first ink chamber 2 with the second ink chamber 3, 9 is a valve which is an opening / closing means for the second communication port, and 10 is an air buffer. This is a recording head attached to the lower part of the container 1. 11 is a supply tube, 12 is a push rod, 13 is an ink storage tank, 14 is a decompression pump, 15 is a nozzle, 16 is a head cap, H is the required liquid level, and h is the head difference.

The recording head 10 is configured so that ink is ejected from a nozzle 15 as droplets by applying a signal corresponding to recording data to a piezoelectric element, a heating element, or the like. Together with a carriage (not shown).

The ink storage tank 13 is provided at a position where a predetermined head difference h is generated with respect to the recording head 10, and a supply tube 11 is connected as a flow path communicating with the air buffer container 1. To supply the ink.

Further, the air buffer container 1 is partitioned into a first ink chamber 2 and a second ink chamber 3 by an inner wall 4.
An ink suction port 5 from a supply tube 11 is provided in the first ink chamber 2, and a recording head 10 is provided in the second ink chamber 3.
Is connected to the second ink chamber 3 and the recording head 10, and a filter 6 for preventing foreign matter from entering so as not to clog the head nozzle 15 is attached.

A first communication port 7 connected to the second ink chamber 3 is provided at an upper portion of the first ink chamber 2, and a second communication port 8 which can be opened and closed by a valve 9 is provided at a lower portion. The valve 9 is formed of an elastic body, and usually has a state in which the second communication port 8 is opened.

Here, the ink supply operation during print recording will be described. Normally, the inside of the air buffer container 1 is filled with ink up to a required liquid level H. When ink is ejected from the nozzles 15 of the recording head 10 mounted on a carriage (not shown), the amount of ink in the air buffer container 1 decreases. The reduced ink is replenished from the ink storage tank 13 through the co-supply tube 11 by the negative pressure in the air buffer container 1,
Maintain the required liquid level H before printing and recording.

When performing a head recovery operation, a head cap 16 provided in a head recovery device (not shown) can seal the front surface of the recording head 10. A pressure reducing pump 14 is connected to the head cap 16,
When the nozzle 15 is clogged or the like, the front surface of the recording head 10 is sealed with a head cap 16 and suction can be recovered by driving the decompression pump 14 in that state.

The head recovery device (not shown) includes:
A push rod 12 is provided, and the head recovery device (not shown) can be moved up and down by a drive source (not shown).

The head cap 16 can be pressed against the front surface of the recording head 10 and sealed by this elevating and lowering.
The push rod 12 can protrude upward.

The operation for returning the lowered liquid level due to the infiltration of air from the wall surface of the supply tube 11 and the defoaming of the ink-dissolved gas to the original required liquid level H will be described below.

When it is detected that the liquid level in the air buffer container 1 has fallen below a predetermined amount by a timer, print record, ink remaining amount sensor or the like (not shown) provided in advance, the carriage is mounted on the head recovery device. As shown in FIG. 2, the front face of the recording head 10 is sealed with the head cap 16 and the push rod 12 provided in the head recovery device is pushed upward to push up the valve 9 to open the second communication port 8 as shown in FIG. close.

When the decompression pump 14 is driven in this state, the ink in the second ink chamber 3 is sucked, the ink level in the first ink chamber 2 rises by that amount, and as shown in FIG. First, the ink in the first ink chamber 2 flows into the second ink chamber 3 from the first communication port 7 and is sucked by the recording head 10, so that the ink is stored in the first ink chamber 2 in the air buffer container 1. In this case, no more ink than the predetermined amount is accumulated.
Here, the decompression pump 14 is stopped, the push rod 12 is lowered, and the valve 9 is opened, so that the state shown in FIG.

(Second Embodiment) In the first embodiment, the opening / closing means for opening / closing the second communication port 8 is a valve 9 formed of an elastic body and driven by a head recovery device. In the example, as shown in FIG. 4, the float valve 20 has a specific gravity slightly lower than that of the ink. Incidentally, the push rod 12 has been removed from the configuration accordingly.

In this case, the amount of suction at the time of liquid level return is set to be sufficiently larger than the amount of ink consumed at the time of printing, and the float valve 20 is brought into close contact with the second communication port 8 by the ink suction force, and the second amount is set. The communication port will be closed.

The other configuration is the same as that of the first embodiment, and the description is omitted.

The recording head according to the first and second embodiments of the present invention is provided with an electrothermal converter for generating thermal energy for discharging recording ink, and the thermal energy applied by the electrothermal heater is provided. Accordingly, the recording head has a structure in which the recording ink is ejected from the ejection port by using the film boiling that generates the ink.

[0037]

As described above, according to the present invention,
The air buffer container is composed of a first ink chamber on the ink suction port side from the ink storage tank and a second ink chamber on the recording head side, and the first ink chamber is filled with a predetermined amount or more of ink. By providing a first communication port through which ink flows to the second ink chamber and a second communication port provided with an opening / closing means for communicating the first and second ink chambers, one tube In the above configuration, there is no need to take a structure that affects the ink supply amount, such as increasing the ink inflow resistance. It is possible to suck a lot of air from the upper air section where the liquid level in the air buffer container is lowered due to the suppression of air bubbles and the like, and the liquid level can be constantly adjusted to the required level. Regardless supply amount, it is possible to provide an ink jet printer and a simple configuration of connection-related mechanism of the carriage and the ink storage tank.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an ink jet printer showing a first embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a liquid level adjustment in the first embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a liquid level adjustment in the first embodiment of the present invention.

FIG. 4 is a schematic sectional view of an ink jet printer showing a second embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 air buffer container 2 first ink chamber 3 second ink chamber 4 inner wall 5 ink suction port 6 filter 7 first communication port 8 second communication port 9 valve 10 recording head 11 supply tube 12 push rod 13 ink storage Tank 14 Decompression pump 15 Nozzle 16 Head cap 20 Float valve H Required liquid level height h Head difference

Claims (6)

[Claims] 1. A means for recording by scanning a recording head or transporting a recording medium and changing a relative position between the recording medium and the recording head, and a portion which is not affected by scanning of the recording head or transportation of the recording medium. An ink jet recording apparatus comprising: an ink storage tank disposed in an air buffer container formed in a recording head; and means for supplying recording ink from the ink storage tank to the recording head via the air buffer container. The air buffer container includes a first ink chamber on the ink suction port side from the ink storage tank and a second ink chamber on the recording head side, and when the first ink chamber is filled with a predetermined amount or more of ink. A first communication port through which ink flows to the second ink chamber; and a second communication port provided with an opening / closing means for communicating the first and second ink chambers. An inkjet printer characterized by the following. 2. The ink jet printer according to claim 1, wherein the first communication port is located higher than the second communication port. 3. The ink jet printer according to claim 1, wherein said opening / closing means is mounted on a carriage. 4. The ink jet printer according to claim 1, wherein said opening / closing means uses a drive source of a head recovery device. 5. An ink jet printer according to claim 1, wherein said opening / closing means is a float valve having a specific gravity lower than that of ink. 6. The recording head includes an electrothermal transducer for generating thermal energy for ejecting recording ink, and the thermal energy applied by the electrothermal heater is used to generate thermal energy.
6. The ink jet printer according to claim 1, wherein the recording head has a structure in which a recording ink is ejected from an ejection port by utilizing film boiling generated by the ink.