KR20140075118A - Ink circulation apparatus, inkjet printer having the same - Google Patents

Abstract

The present invention relates to an ink circulation device and an inkjet printer including the same, including an ink pack which supplies ink to or recovers ink from an inkjet print head; an ink supply path which supplies ink from the ink pack to the inkjet print head; an ink recovery path which recovers the ink from the inkjet print head to the ink pack; a first pump provided in the ink recovery path; a second pump provided in the ink supply path; a first pressure sensor provided between the first pump and the inkjet print head; and a second pressure sensor provided between the second pump and the inkjet print head. The input voltage or current of the first or second pump can be changed so that the pressure which is set and the pressure which is detected in the first pressure sensor are equal according to the pressure detected in the first pressure sensor. In addition, the ink pack can be periodically replaced so as to store clean ink and remove foreign substances or air accumulated during the circulation.

Description

Ink circulation apparatus, ink jet printer including same,

The present invention relates to an ink circulating apparatus and an ink jet printer including the same.

The ink jet printer discharges ink from the ink-jet printhead by driving the ink-jet printhead, and the micro-air dissolved in the ink existing in the ink-jet printhead due to the pressure change and the temperature change occurring at the time of driving the ink- Occurs. As a result, the non-discharge of the ink and the deflection of the ink discharge occur, and there is a problem that a line or the like occurs on the substrate of the printed matter after the ink discharge.

Therefore, the ink jet printer is configured to eliminate the portion where the air gush occurs in the supply path for supplying the ink to the ink-jet print head, or to provide a degassing device in the supply path to supply the ink to the ink-jet printhead .

In an ink jet printer equipped with a degassing device, for example, the inlet and outlet of the degassing module are connected in series to the pipe serving as the supply path. Further, a vacuum pump is connected to the degassing module to keep the inside of the degassing module under vacuum. This removes the gas dissolved in the ink, that is, the deaerator ink is produced, and the deaerator ink is supplied to the ink-jet printhead through the supply path. As a result, it is possible to control the reduction of bubbles generated by the driving of the ink-jet head and the non-discharge of ink generated as the gas remaining in the pipe in the initial state dissolves in the ink.

However, when the degassing ink is produced and supplied, when the degassing ink contacts the air, air is dissolved in the ink, and the air returns to the saturated state immediately.

Therefore, it is required to supply the ink of the intestinal tract to the ink-jet printhead while maintaining the deaeration of the ink without leaving air in the supply path.

In recent years, inkjet printers have been widely used in industrial applications. For example, inkjet printers are used to directly form circuit patterns by spraying ink formed by melting metals such as gold and silver on a flexible printed circuit board (FPCB) (LCDs), organic light emitting diodes (OLEDs), and solar cells.

At this time, since the solid fine particles such as metal such as gold and silver are dispersed in the ink component, the solid component is precipitated unless the ink is circulated, resulting in discharge failure.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and it is an object of the present invention to provide an ink circulating device capable of supplying sufficiently deaerated ink to an inkjet printhead and preventing solid components from precipitating in the ink, And an ink circulation method.

It is another object of the present invention to continuously monitor the ink pumping pressure of a collection port of an ink-jet printhead so that the pressure inside the ink-jet printhead can be maintained constant.

It is another object of the present invention to provide an ink jet print head capable of precisely and error-free control by simplifying a control method of keeping the pressure inside the ink jet head constant.

An ink circulating apparatus according to an embodiment of the present invention includes an ink pack for supplying or recovering ink to an inkjet printhead; An ink supply path for supplying ink from the ink pack to the inkjet printhead; An ink recovery path for recovering ink from the ink-jet printhead to the ink pack; A first pump provided in the ink recovery passage; A second pump provided in the ink supply path; A first pressure sensor disposed between the first pump and the inkjet printhead; And a second pressure sensor provided between the second pump and the inkjet printhead.

The ink circulation apparatus according to an embodiment of the present invention may further include a controller for adjusting an input voltage or current of the first and second pumps.

In the ink circulating apparatus according to an embodiment of the present invention, the controller may control the first or second pump so that the pressure set by the first pressure sensor and the pressure sensed by the first pressure sensor become equal to each other, The input voltage or current can be changed.

In the ink circulation apparatus according to an embodiment of the present invention, when the pressure sensed by the first pressure sensor is larger than the pressure set by the first pressure sensor, a voltage or current Can be input.

In the ink circulation apparatus according to an embodiment of the present invention, when the pressure sensed by the first pressure sensor is smaller than the pressure set by the first pressure sensor, a voltage or current Can be input.

The ink circulation apparatus according to an embodiment of the present invention can maintain the state when the pressure sensed by the second pressure sensor is equal to the pressure sensed by the first pressure sensor.

In the ink circulation apparatus according to an embodiment of the present invention, a filter may be provided at the suction port of the first and second pumps.

In the ink circulating apparatus according to an embodiment of the present invention, the ink supply path may be provided with a degassing apparatus.

In the ink circulating apparatus according to an embodiment of the present invention, the ink supply path is provided with a supply valve, the ink recovery path is provided with a recovery valve, the supply valve is opened, and the recovery valve The inkjet printhead may be purged by operating the pump to adjust the input voltage or current value of the second pump so that the pressure value of the second pressure sensor is a predetermined value.

An inkjet printer according to an embodiment of the present invention includes an ink circulating device; An inkjet printhead which receives ink from the ink circulating device and discharges the ink; And an ink tank connected to the ink recovery path to supply ink through the ink replenishing passage.

In the ink-jet printer according to the embodiment of the present invention, the ink pack is provided with a weight sensor for estimating the ink amount of the ink pack. When the amount of ink in the ink pack is sensed below a predetermined value, The tank may be supplied with ink or the ink pack may be replaced.

In the ink jet printer according to an embodiment of the present invention, the ink replenishing passage is provided with a replenishing valve, and the replenishing valve can be opened when ink is supplied from the ink tank to the ink pack.

In the inkjet printer according to the embodiment of the present invention, the ink supply path is provided with a supply valve, and when the ink is supplied from the ink tank to the ink pack, the supply valve is closed .

According to the present invention, it is possible to provide an ink circulating apparatus, an ink jet printer including the ink circulating apparatus, and an ink circulating method capable of supplying ink sufficiently deaerated to the ink-jet printhead and preventing solid components in the ink from settling.

Further, by using the present invention, it is possible to continuously monitor the ink pumping pressure of the ink supply port and the recovery port of the inkjet printhead, so that the pressure inside the inkjet printhead can be kept constant.

In addition, by using the present invention, it is possible to make accurate and error-free control by simplifying the control method of keeping the pressure inside the inkjet print head constant.

In addition, the present invention can include a purging function of an ink-jet printhead and a structure and a control method for easily supplying ink to the ink pack. In addition, since the air or small foreign matter collected during the ink circulation can be collected in the ink pack and the pack can be periodically exchanged, fresh ink can be exchanged without the user touching the ink directly, Can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view showing a configuration in which ink circulates using an ink circulating apparatus according to an embodiment of the present invention. FIG.
2 is a view showing a configuration for purging an inkjet printhead using an ink circulating apparatus according to an embodiment of the present invention.
3 is a view showing a configuration for supplying ink from an ink tank to an ink pack using an ink circulating apparatus according to an embodiment of the present invention.
4 is a block diagram showing an ink circulation control apparatus according to an embodiment of the present invention.
5 is a flowchart showing an ink circulation control method according to an embodiment of the present invention.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventive concept. Other embodiments that fall within the scope of the inventive concept may be easily suggested, but are also included within the scope of the present invention.

In the drawings, the same reference numerals are used to designate the same or similar components in the same spirit of the drawings.

FIG. 1 is a view showing a configuration in which ink is circulated by using an ink circulating apparatus according to an embodiment of the present invention, and FIG. 2 is a view showing a state where the ink circulating apparatus according to an embodiment of the present invention is purged Fig. 3 is a view showing a configuration for supplying ink from the ink tank to the ink pack using the ink circulating apparatus according to the embodiment of the present invention. Fig.

First, a structure of an inkjet printer in which ink is circulated by using an ink circulation control apparatus according to an embodiment of the present invention will be described with reference to FIG.

The inkjet printer 100 shown in FIG. 1 may include an inkjet printhead 110 and an ink pack 120. Of course, an ink supply path 140 for supplying ink from the ink pack 120 to the inkjet printhead 110 and an ink recovery path 140 for recovering ink from the inkjet printhead 110 to the ink pack 120 (130).

The inkjet printhead 110 has an ink flow path formed therein and discharges ink to the nozzle 111 through pressure or volume change in the ink flow path by driving of an actuator (not shown) Jet printhead, and thus a detailed description thereof will be omitted.

The ink pack 120 can be formed in a multi-layered structure so that the sufficiently deaerated ink is filled and the air is blocked. Also, the ink pack 120 may be provided with a weight sensor 121 for measuring the amount of ink filled therein. The weight sensor 121 is not limited as long as it can measure the amount of ink filled in the ink pack 120.

The ink pack 120 is connected to the inkjet printhead 110 by an ink supply path 140 so that ink can be supplied from the ink pack 120 to the inkjet printhead 110. That is, an ink supply path 140 for supplying ink from the ink pack 120 to the inkjet printhead 110 may be provided. The ink supply path 140 is provided with a second pump 141 to supply ink to the inkjet printhead 110 by pumping ink from the ink pack 120. A second filter 144 may be provided at an ink injection port of the second pump 141.

Also, the ink supply path 140 may be provided with a supply valve 143. The supply valve 143 may maintain the open state when the ink filled in the ink pack 120 is supplied to the inkjet printhead 110. Of course, when the ink jet printer 100 performs another function, the supply valve 143 can be kept in a locked state. This will be described below with reference to FIG.

In addition, the ink supply path 140 may be provided with a degassing device 145. In more detail, the deaerator 145 may be provided between the second pump 141 and the inkjet printhead 110. This is because ink pumped through the second pump 141 may generate bubbles due to a pressure difference.

The ink supply path 140 may include a second pressure sensor 142. More specifically, the second pressure sensor 142 may be provided between the second pump 141 and the inkjet printhead 110. The ink is pumped by the second pump 141 and supplied to the supply port 112 of the inkjet printhead 110 so as to measure the pressure of the ink supplied to the inkjet printhead 110 most accurately. Accordingly, the second pressure sensor 142 may be disposed as close as possible to the ink supply port 112 of the inkjet printhead 110.

The ink pack 120 is connected to the inkjet printhead 110 by an ink recovery path 130 so that the ink of the inkjet printhead 110 can be recovered into the ink pack 120. That is, an ink recovery path 130 in which ink is recovered from the ink-jet printhead 110 to the ink pack 120 may be provided. The ink recovery path 130 may include a first pump 131 for pumping ink from the inkjet printhead 110 and recovering the ink into the ink pack 120. A first filter 134 may be provided at the ink inlet of the first pump 131.

In addition, the ink recovery passage 130 may be provided with a recovery valve 133. When the inkjet printhead 110 is collected by the ink pack 120, the recovery valve 133 may maintain the open state. Of course, when the ink jet printer 100 performs another function, the supply valve 143 can be kept in a locked state. This will be described below with reference to FIG. 2 and FIG.

In addition, the ink recovery passage 130 may be provided with a degassing device (not shown). More specifically, the deaerator (not shown) may be provided between the first pump 131 and the ink pack 120. When the ink pumped through the first pump 131 is stored in the ink pack 120, the ink must be deaerated. In addition, after the ink is pumped by the second pump 131, bubbles may be generated due to the pressure difference.

In addition, the ink recovery passage 130 may include a first pressure sensor 132. More specifically, the first pressure sensor 132 may be provided between the first pump 131 and the inkjet printhead 110. The ink is pumped by the first pump 131 and sucked in the recovery port 113 of the inkjet printhead 110 so as to measure the pressure of the ink recovered in the inkjet printhead 110 most accurately. Accordingly, the first pressure sensor 132 may be disposed as close as possible to the ink recovery port 113 of the inkjet printhead 110.

The inkjet printer 100 having the above-described structure operates both the first and second pumps 131 and 141 in a state where both the supply valve 143 and the recovery valve 133 are opened, 110 to be continuously circulated. That is, the ink of the ink pack 120 is supplied to the inkjet printhead 110 on the ink supply path 140 by the pumping of the second pump 141, and the supplied ink is pumped to the first pump 131 The ink is returned to the ink pack 110 by the ink recovery passage 130. [

In this case, the first and second pumps 131 and 141 are basically operated to generate the same pumping pressure by the same input voltage. However, when continuously operated, there is a difference in the pumping pressure between the first pump 131 and the second pump 141 according to other requirements.

Since the first pump 131 and the second pump 141 are pumps arranged in the direction of the recovery port 113 and the supply port 112 of the inkjet printhead 110 respectively, The internal pressure of the inkjet printhead 110 is changed. When the internal pressure of the inkjet printhead 110 is changed, the meniscus formed on the nozzle 111 may not be properly maintained. In addition, when the internal pressure of the inkjet printhead 110 is lowered, the micro-air dissolved in the ink may expand into bubbles, which may affect the performance of the inkjet printer 100.

 Accordingly, in the present invention, the input voltage or current of the first pump 131 and the input voltage or current of the second pump 141 are changed by a simple control method, Control device and method. This will be described later in detail with reference to FIG.

The ink jet printer 100 according to an embodiment of the present invention may include an ink tank 150 connected to the ink recovery path 130 and supplying ink through the ink replenishment path 151. The ink recovery passage 130 and the ink replenishment passage 151 may meet at an intersection 154.

In this case, the ink replenishment passage 151 may intersect the ink recovery passage 130, the recovery valve 133, and the first pump 131. This is because it is necessary to use the first pump 131 at the time of replenishing the ink in the ink tank 150, and the ink exchange with the inkjet printhead 110 must be stopped.

 The ink tank 150 can supply ink when the ink in the ink pack 120 is reduced to a predetermined amount or less. That is, ink may be supplied to the ink pack 120 based on the ink amount measurement of the weight sensor 121 provided in the ink pack 120.

The ink replenishment passage 151 may be provided with a supplemental valve 153. The supplemental valve 153 may maintain the opened state when ink is supplied to the ink pack 120 from the ink tank 150. Of course, when the ink jet printer 100 performs other functions, it can be kept closed.

Meanwhile, the recovery valve 133 and the supplementary valve 153 may be integrally provided and disposed at the intersection 154. In other words, the valve is provided in a 'T' shape instead of a straight line, so that the valve is opened so that the ink flows only in the ink recovery passage 130. In this case, the portion connected to the ink replenishing passage 151 is kept closed - opening the valve so that the ink supplied from the ink replenishing passage 151 flows to the ink recovery passage 130 or opening the valve in the ink replenishing passage 151 along the ink recovery passage 130, The valve can be opened only in the direction of the arrow.

Next, a method of purging the ink-jet printhead using the ink circulation apparatus according to one embodiment of the present invention will be described with reference to FIG. Basically, the structure of the ink jet printer 100 described with reference to FIG. 1 is used as it is, and there is a difference only in the open state of the valve and the utilization of the pump.

The inkjet printhead 110 may need to be purged from the inside of the inkjet printhead 110 because the inkjet printhead 110 may be settled or otherwise contaminated with solids by the first use or continuous use. Thus, the present invention provides such purging means.

That is, the inkjet printhead 110 can be purged by continuously discharging the ink through the nozzle 111 in the inkjet printhead 110 while continuously supplying ink.

Accordingly, in the present invention, the supply valve 143 disposed in the ink supply path 140 can be kept open and only the second pump 141 can be operated. In this case, the voltage or current can be supplied to the second pump 141 so that the value of the second pressure sensor 142 becomes a predetermined purging pressure value. The method is similar to the pressure control method of the first pressure sensor 132. The ink of the ink pack 110 can be supplied to the inkjet printhead 110 along the ink supply path 140 and discharged to the ink droplet 111a through the nozzle 111 immediately.

In this case, the recovery valve 133 provided in the ink recovery passage 130 is kept in a locked state and the first pump 131 must be stopped.

Next, referring to FIG. 3, a method of filling ink from an ink tank into an ink pack of an inkjet printhead using an ink circulating apparatus according to an embodiment of the present invention will be described. Basically, the structure of the ink jet printer 100 described with reference to FIG. 1 is used as it is, and there is a difference only in the open state of the valve and the utilization of the pump.

The ink jet printer 100 is provided with an ink pack 110 in which ink sufficiently deaerated is filled and when the ink filled in the ink pack 110 falls below a predetermined amount, .

Thus, the ink can be supplied from the ink tank 150 connected to the ink circuit number 130 by the ink replenishment passage 151. The ink can be pumped from the ink tank 150 to the ink pack 120 by operating the first pump 131 while both the recovery valve 133 and the supply valve 143 are closed. Of course, the replenishment valve 153 of the ink replenishment passage 151 can maintain the open state.

4 is a block diagram showing an ink circulation control apparatus according to an embodiment of the present invention.

4, the ink circulation control apparatus 10 according to an embodiment of the present invention includes a weight sensor 20, a pump control unit 30, a central processing unit 40, a pressure control unit 50, and a valve control unit 60 ). Of course, the central processing unit 40 may be connected to both the weight sensor 20, the pump control unit 30, the pressure control unit 50, and the valve control unit 60 to centrally control various controls. The ink circulation control apparatus 10 according to an embodiment of the present invention can be mounted and used by various devices such as terminals, computers, mobile phones, and PDAs. Of course, all of the various devices not illustrated can be utilized.

The weight sensor 20 may be provided in the ink pack 110 to measure the ink amount of the ink pack 110 and to transmit the information to the central processing unit 40. When the ink amount of the ink pack 110 falls below a predetermined reference, the central processing unit 40 can perform the processing of filling the ink pack 110 with the ink in the ink tank 150. [ In this case, the central processing unit 40 may control the pump control unit 30 and the valve control unit 60 to fill the ink pack 110 with ink.

That is, when the weight sensor 20 senses that the ink amount of the ink pack 110 is equal to or less than a predetermined amount to the central processing unit 40, the central processing unit 40 causes the valve control unit 60 to receive the supplemental valve 153 And commands the remaining supply valve 143 and the recovery valve 133 to close. Further, the first pump 131 may be operated to the pump control unit 30 and the second pump 141 may be instructed to stop the operation. In addition, the central control unit can notify the user so that regular ink pack replacement is possible.

The pump control unit 30 receives various commands from the central processing unit 40 and can control the operation of the first pump 131 and the second pump 141. For example, in the case of normal circulation of ink (see FIG. 1), it is possible to control both the first pump 131 and the second pump 141 to operate. Of course, the input voltage of the first pump 131 can be maintained and the input voltage or current of the second pump 141 can be changed so that the internal pressure of the inkjet printhead 110 can be kept constant. The details of this will be described in detail with reference to FIG.

The pressure control unit 50 may transmit the pressure information sensed by the first pressure sensor 132 and the second pressure sensor 142 to the central processing unit 40. The central processing unit 40 can adjust the pressure of the inkjet printhead 110 to be constant by the transmitted pressure information.

The valve control unit 60 can control the operation of the recovery valve 133, the supply valve 143 and the supplemental valve 153 in accordance with a command from the central processing unit 40. [

In addition, the central processing unit 40 may perform a purging function of the inkjet printhead 110. The purging of the inkjet printhead 110 may be repeatedly performed before the first use or at predetermined intervals.

There is a need to purge the interior of the inkjet printhead 110 because the inkjet printhead 110 may be settled solids or otherwise leave the interior by its first use or continued use. Accordingly, in the present invention, such purging can be performed by the central processing unit 40. That is, the central processing unit 40 continuously supplies the ink to the inkjet printhead 110 while continuously discharging the ink from the inkjet printhead 110 through the nozzle 111 for a predetermined period of time, Can be purged.

The central processing unit 40 may instruct the valve control unit 60 to close the recovery valve 133 and the replenishment valve 153 and open the supply valve 143 only. The central processing unit 40 may instruct the pump controller 30 to stop the operation of the first pump 131 and to operate the second pump 141 only. Of course, in this case, the input voltage or current of the second pump 141 may be selected in consideration of the size and other matters of the ink-jet printhead 110.

5 is a flowchart showing an ink circulation control method according to an embodiment of the present invention.

Referring to Figure 5, a method for controlling ink normal circulation according to one embodiment of the present invention is disclosed. The control algorithm shown in Fig. 5 uses the ink circulating apparatus of Fig. 1 and can be implemented using the control apparatus of Fig. That is, various devices such as various terminals, computers, mobile phones, and PDAs can be connected to the inkjet printer 100 and implemented.

A method of controlling ink normal circulation according to the present invention is a method for controlling the ink normal circulation according to the first and second aspects of the present invention for measuring the pressure of the ink recovered by the first pump and the pressure of the ink supplied by the second pump to the ink- Measuring a first pressure and a second pressure by a pressure sensor, selecting whether or not to adjust a voltage or a current input to the first or second pump according to the measured first pressure, 2 < / RTI > input voltage or current of the pump.

The ink of the inkjet printhead 110 is collected in the ink pack 120 and the ink is ejected from the inkjet printhead 110 in consideration of the size and type of the inkjet printhead 110. [ The pressure P 1 of the first pump 131 used to set the pressure P 1 is selected and the pressure voltage V 1 corresponding thereto is selected as the input voltage (S 10, S 20).

The input voltage V2 of the second pump 141, which is located on the supply port 112 side of the inkjet printhead 110 and used to supply ink from the ink pack 120 to the inkjet printhead 110, is set (S30). As a result, both the first and second pumps 131 and 141 are maintained in an operating state. The supply valve 143 and the recovery valve 133 are both opened, and the supplementary valve 153 can be maintained in a closed state because the ink is normally circulated in the inkjet printhead 110.

Theoretically, since the input voltages of the first and second pumps are the same, the same pressure should be formed on the side of the recovery tool 113 and the side of the supply tool 112 with the inkjet printhead 110 as the center. That is, since the pressure for supplying the ink around the inkjet printhead 110 is equal to the pressure for recovering the ink, the input and the output are the same.

However, the inkjet printhead 110 itself has an apparatus for ejecting ink to eject ink through the nozzles 111. In addition, due to various other factors, the inkjet printhead 110 is provided with the ink supply port 112 side The difference in pressure between the two will result.

The input pressure V1 of the first pump 131 remains the same and the pressure P2 of the ink pumped by the second pump 141 is continuously used by the first pressure sensor 132 (S40).

The pressure P2 sensed by the first pressure sensor 132 may be greater than or less than or equal to the preset pressure P1 in the first pressure sensor 132 at step S50.

The corrected input voltage or current input to the second pump 141 based on the pressure P2 sensed by the first pressure sensor 132 is greater than the input voltage V1 of the first pump 131 , Smaller or equal (S60).

When the pressure P2 sensed by the first pressure sensor 132 is greater than the pressure P1 preset by the first pressure sensor 132 in step S51, (V2 = V1-a), which is lower than the input voltage of the first pump 141 or the current -V1, and inputs the input voltage or the current -V2 of the first pump 141 (S61) - 'a' is a positive number -.

Next, when the pressure P2 sensed by the first pressure sensor 132 is smaller than the pressure P1 preset by the first pressure sensor 132 (S52), the input of the second pump 141 (V2 = V1 + a), which is higher than the input voltage of the first pump 141 or the voltage (V2 = V1 + a) larger than the current (V1) - 'a' is a positive number.

Finally, when the pressure P2 sensed by the first pressure sensor 132 is equal to the pressure P1 preset by the first pressure sensor 132 (S53), the state of the second pump 141 .

The first pressure sensor 132 is continuously monitored to continuously change the input voltage V2 of the second pump 141 so that the first pressure sensed by the first pressure sensor 132 is set in advance It can be maintained at the same pressure. Accordingly, since the pressure inside the inkjet printhead 110 is kept constant, the ink ejection performance of the inkjet printhead 110 can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the appended claims.

100: inkjet printer
110: inkjet printhead
120: Ink Pack
130: ink recovery path
140: ink supply path
150: ink tank

Claims (13)

An ink pack for supplying or recovering ink to the inkjet printhead;
An ink supply path for supplying ink from the ink pack to the inkjet printhead;
An ink recovery path for recovering ink from the ink-jet printhead to the ink pack;
A first pump provided in the ink recovery passage;
A second pump provided in the ink supply path;
A first pressure sensor disposed between the first pump and the inkjet printhead; And
And a second pressure sensor provided between the second pump and the inkjet printhead. The method according to claim 1,
Further comprising a control unit for adjusting an input voltage or current of the first and second pumps. 3. The method of claim 2,
Wherein the control unit changes the input voltage or current of the first or second pump so that the pressure set by the first pressure sensor and the sensed pressure become equal to each other according to the pressure sensed by the first pressure sensor. The method of claim 3,
Wherein a voltage or current smaller than the input voltage of the first pump is input to the second pump when the pressure detected by the first pressure sensor is larger than the pressure set by the first pressure sensor. The method of claim 3,
Wherein a voltage or a current larger than an input voltage of the first pump is input to the second pump when the pressure detected by the first pressure sensor is smaller than the pressure set by the first pressure sensor. The method of claim 3,
And maintains the state when the pressure sensed by the second pressure sensor is equal to the pressure sensed by the first pressure sensor. The method according to claim 1,
And a filter is provided in the suction port of the first and second pumps. The method according to claim 1,
Wherein the ink supply path is provided with a degassing device. The method according to claim 1,
Wherein the ink supply path is provided with a supply valve, the ink recovery path is provided with a recovery valve,
The supply valve is opened and the second pump is operated with the recovery valve closed to adjust the input voltage or current value of the second pump so that the pressure value of the second pressure sensor is a predetermined value, An ink circulating apparatus capable of purging an ink-jet printhead. An ink circulating apparatus according to any one of claims 1 to 9,
An inkjet printhead which receives ink from the ink circulating device and discharges the ink; And
And an ink tank connected to the ink recovery path to supply ink through the ink replenishing passage. 11. The method of claim 10,
The ink pack is provided with a weight sensor for estimating the ink amount of the ink pack,
Wherein when the amount of ink in the ink pack is sensed at a predetermined value or less by the weight sensor, the ink tank receives the ink from the ink tank or informs the replacement of the ink pack. 12. The method of claim 11,
Wherein the ink replenishing passage is provided with a replenishing valve and the replenishing valve is opened when ink is supplied from the ink tank to the ink pack. 13. The method of claim 12,
Wherein the ink supply path is provided with a supply valve, and when the ink is supplied from the ink tank to the ink pack, ink is filled in the ink pack while the supply valve is closed.

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