JP5413229B2 - Liquid ejector - Google Patents

Description

  The present invention relates to a technique for ejecting liquid from an ejection head.

A so-called inkjet printer can print a high-quality image by ejecting an accurate amount of ink to a precise position from a fine ejection nozzle. In addition, by utilizing this technique and ejecting various liquids instead of ink toward the substrate, it is also possible to manufacture electrodes, sensors, biochips, and the like.

In such a technique, a liquid such as ink is ejected by using an ejection head having an ejection nozzle. If the properties in the jet head have increased due to thickening, etc., the liquid with degraded properties can be obtained by operating the suction pump connected to the cap with the jet nozzle covered with the cap. Suction cleaning, which is an operation of sucking the air from the spray nozzle, is performed. Also,
When performing suction cleaning, it is necessary to form a sealed space between the cap and the ejection head by pressing the cap against the ejection head. For this purpose, the cap is brought into contact with the exact position of the ejection nozzle. This is not always easy.
Therefore, instead of suction cleaning, pressurization cleaning, which is an operation to push the liquid in the ejection head by pressing it from the upstream side and discharge it to the cap, can be omitted, and the operation to cover the ejection nozzle with the cap can be omitted Sometimes it is done.

Further, since the ejection head ejects the liquid by pressurizing the liquid, it is necessary to keep the pressure of the liquid supplied to the ejection head at an appropriate pressure in order to eject an accurate amount of liquid. However, it is difficult to keep the pressure of the liquid supplied to the ejection head constant due to the effect of pressure loss in the passage for supplying the liquid to the ejection head. Therefore, the liquid is supplied up to the ejection head by pressurization, and when the pressure in the ejection head falls below a predetermined pressure, the pressure adjustment valve is opened to supply the required amount of liquid to the ejection head. A technique for adjusting the pressure of the liquid to be supplied to an appropriate pressure has been proposed. (Patent Document 1)

JP 2004-142405 A

However, if the pressure of the liquid supplied to the ejection head is kept constant by the pressure regulating valve, there is a problem that pressure cleaning cannot be performed, and as a result, suction cleaning must be performed. That is, the pressure regulating valve has a structure in which the valve does not open even when pressurized from the upstream side of the pressure regulating valve so that liquid is not supplied to the ejection head by different pressures. Therefore, there is a problem that even if the ejection head is pressurized from the upstream side, the applied pressure is blocked by the pressure control valve, and pressure cleaning that is simpler than suction cleaning cannot be performed.

The present invention has been made to solve the above-described problems of the prior art,
An object of the present invention is to provide a technique capable of performing pressure cleaning while keeping the pressure of the liquid supplied to the ejection head constant by a pressure regulating valve.

In order to solve at least a part of the problems described above, the liquid ejecting apparatus of the present invention employs the following configuration. That is,
A liquid ejecting apparatus that ejects liquid from an ejection nozzle provided in an ejection head,
A liquid supply unit that pumps the liquid ejected from the ejection nozzle toward the ejection head via a liquid flow path ;
Pressure adjusting means provided in the liquid flow path between the liquid supply unit and the ejection head, and the pressure of the liquid between the pressure adjustment means and the ejection head is within a predetermined pressure range. Pressure regulating means having a pressure regulating valve that opens only when,
By opening a bypass passage connecting the upstream side and the downstream side of the pressure regulating valve and guiding the liquid pressure-fed from the liquid supply unit to the ejection head, the liquid in the ejection head is discharged from the ejection nozzle. And a pressure cleaning means for performing the cleaning operation.

In such a liquid ejecting apparatus of the present invention, the liquid pumped by the liquid pumping means is applied to the ejecting head only when the pressure of the liquid between the pressure adjusting means and the ejecting head falls within a predetermined pressure range. Supplied. For this reason, even when fluctuations occur in the pressure supplied due to the difference in flow path resistance when liquid is pumped, the liquid pressure in the ejection head can be maintained at a constant pressure, and the liquid is ejected appropriately. can do. However, in the configuration provided with the pressure adjusting means in this way, even when liquid is pumped toward the jet head to perform pressure cleaning in the jet head, the pressure regulating valve does not open with the pressure of the pumped liquid. Therefore, it is impossible to perform pressure cleaning in which the liquid in the ejection head is discharged from the ejection nozzle and cleaned by the pressure applied by the liquid pressure feeding means. Therefore, in the liquid ejecting apparatus of the present invention, a bypass path that connects the upstream side and the downstream side of the pressure adjusting means is provided, and when performing pressure cleaning, the bypass passage is opened and the pressure feeding means from the liquid pressure feeding means. It is possible to directly guide the liquid to the ejection head.

In this way, it is possible to perform pressure cleaning while providing the pressure adjusting means. Accordingly, it is possible to perform a maintenance operation for discharging the liquid having deteriorated properties outside the ejection head without performing the suction cleaning, and as a result, the cap, which is a necessary operation during the suction cleaning, is attached to the ejection nozzle accurately. Since it is possible to omit the operation of making contact with the correct position, the maintenance operation can be simplified. Further, in a state where pressure cleaning is not performed, if the bypass passage is closed, the pressure-fed liquid is supplied to the ejecting head via the pressure adjusting means, so that the pressure of the liquid supplied to the ejecting head is kept constant. It becomes possible to keep.

In the above-described liquid ejecting apparatus of the present invention, when pressure cleaning is performed, the liquid is pumped from the liquid supply unit toward the ejecting head with a pressure higher than that in a state where pressure cleaning is not performed. It is good.

In this way, by increasing the pressure of the liquid pumped to the ejection head at the time of pressure cleaning, the liquid in the ejection head can be pushed out by a larger pressure, so that the discharge capability of the liquid with deteriorated properties can be increased. It becomes possible. In addition, since the liquid is not pumped by a high pressure even when pressure cleaning is not performed, it is possible to avoid applying an extra pressure load to the liquid pumping means for pumping the liquid. Become.

It is explanatory drawing which showed the rough structure of the liquid ejecting apparatus of a present Example using a line printer as an example. It is explanatory drawing which shows a state when a head unit is seen from the bottom face side. It is explanatory drawing which showed the structure for the line printer of a present Example to supply ink to an ejection head. It is explanatory drawing which showed the detailed structure of the pressure regulation valve. It is explanatory drawing which showed the operation | movement which a pressure regulating valve adjusts the supply pressure of ink. It is explanatory drawing which showed the method of performing pressurization cleaning using a bypass flow path. FIG. 10 is an explanatory diagram illustrating a configuration for a line printer according to a modification to supply ink to an ejection head.

Hereinafter, in order to clarify the contents of the present invention described above, examples will be described in the following order.
A. Device configuration:
B. Ink supply method of this embodiment:
C. Variations:

A. Device configuration :
FIG. 1 is an explanatory diagram showing a rough structure of a liquid ejecting apparatus according to the present embodiment using a line printer 1 as an example. As shown in the figure, the line printer 1 of the present embodiment has a box-like outer shape, and a monitor panel 2 and an operation panel 3 for user operation are provided on the upper surface. It has been. Further, the front of the line printer 1 is provided with a cartridge replacement door 4 that is opened when the ink cartridge is replaced, and a paper feed door 5 that is opened when the printing paper is loaded. A paper discharge port 6 through which printed printing paper is discharged is provided.

Inside the line printer 1, a plurality of units or parts for executing various functions are mounted. First, a head unit 30 that ejects ink onto printing paper is provided at a substantially central position of the line printer 1. An ink supply unit 60 that supplies ink to the head unit 30 is provided below the head unit 30.
Is mounted with an ink cartridge 62 filled with ink. In the line printer 1 of this embodiment, four colors of ink, black ink (K ink), cyan ink (C ink), magenta ink (M ink), and yellow ink (Y ink) can be used for printing. Correspondingly, four ink cartridges 62 filled with ink of each color are attached to the ink supply unit 60.

On the paper surface of FIG. 1, a paper feed cassette 10 into which printing paper is loaded is provided at the lower left position of the head unit 30, and the paper feed roller 20 is located at a position in contact with the upper surface of the right end of the paper feed cassette 10. Is provided. Further, a paper feed motor 22 is connected to the back side of the paper feed roller 20, and when the paper feed motor 22 is driven to rotate the paper feed roller 20, printing sheets are fed one by one from the paper feed cassette 10. It is conveyed toward the head unit 30. In FIG. 1, the conveyance path of the printing paper is indicated by a thick broken line.

In addition, an area on the right side of the head unit 30 is an empty space on the paper surface of FIG. 1, and a cap 40, a suction pump 50, a waste liquid tank 52, and the like are provided below the empty space. Although details will be described later, in the line printer 1 of the present embodiment, when the ink properties deteriorate due to the ink being left in the head unit 30 for a long time, the head unit 30 is moved to an empty space on the right side. After the movement, the ink in the head unit 30 is pressurized to discharge the deteriorated ink to the cap 40 (pressure cleaning). Further, the ink discharged to the cap 40 by the pressure cleaning is sucked by the suction pump 50 and stored in the waste liquid tank 52.

A power supply unit 70 for supplying power to the line printer 1 and a control unit for controlling various movements of the line printer 1 are located immediately below the portion where the monitor panel 2 and the operation panel 3 are provided. 80 etc. are mounted.

Next, the printing operation of the line printer 1 will be described with reference to FIG. First, a plurality of printing sheets are loaded in the sheet feeding cassette 10. The printing paper loaded in the paper feed cassette 10 is pushed up by a spring (not shown), and the paper feed roller 2 provided above.
It is pressed to 0. The paper feed roller 20 is an elongated member having a substantially semicircular cross section formed by dividing a metal elongated cylinder in half in the length direction, and the side surface corresponding to the circumferential portion is formed of a rubber material. A paper feed motor 22 is connected to one end of the paper feed roller 20, and by rotating the paper feed roller 20 by the paper feed motor 22, print sheets are fed one by one from the paper feed cassette 10 to the head unit 30. Send it out.

A plurality of guide rollers 24 are provided between the paper feed roller 20 and the head unit 30. The guide roller 24 is driven and rotated by a motor (not shown) to convey the printing paper to the head unit 30 while guiding the printing paper.

The head unit 30 is provided so as to straddle the printing paper on the printing paper conveyance path, and a plurality of inks are ejected to the bottom side of the head unit 30 (that is, the side facing the printing paper). Is provided (see FIG. 2). Head unit 3
0, the ink cartridge 62 of the ink supply unit 60 is connected via a flow path (not shown), and the ink accommodated in the ink cartridge 62 is a plurality of ejection heads provided on the lower surface side of the head unit 30. Is injected from.

FIG. 2 is an explanatory diagram showing a state when the head unit 30 is viewed from the bottom surface side (side facing the printing paper). As shown in the figure, on the bottom surface of the head unit 30 of the present embodiment, there are provided four sets (a total of 24) of jet heads 32 each having a substantially rectangular shape. In addition, three jet heads 32 in each group are arranged in two rows by three, and the jet heads 32 in each row are arranged alternately. Further, each ejection head 32 is provided with a plurality of ejection nozzles that eject ink. The lower surface of the ejection head 32 provided with such ejection nozzles may be referred to as a “nozzle surface”.

Such jet heads 32 are arranged in a staggered manner, so that six jet heads 3 are arranged.
2 constitute a single injection unit 34. As described above, since the head unit 30 of the present embodiment is provided with 24 ejection heads 32, after all, there are four ejection units, and each ejection unit 34 ejects Y ink. Ejecting unit 34y, ejecting unit 34m ejecting M ink, ejecting unit 3 ejecting C ink
4c, an ejection unit 34k that ejects K ink.

Below the head unit 30, facing the bottom surface of the head unit 30,
A platen that supports the printing paper from the back is provided (not shown). Feed roller 2
0 and the printing paper conveyed by the guide roller 24 are conveyed on the platen,
During this time, ink is ejected from a plurality of ejecting heads 32 provided on the bottom surface of the head unit 30, and an image is printed on the printing paper. The printing paper on which the image is thus printed is bent downward in the traveling direction by the guide roller 24 provided on the downstream side of the head unit 30, and then passes through the lower side of the waste liquid tank 52 from the paper discharge port 6 to the line printer. 1 is discharged to the outside. Here, in the line printer 1 of the present embodiment, when ink is ejected from the plurality of ejection heads 32 provided in the head unit 30, the ink is supplied to the ejection head 32 using the following configuration.

B. Ink supply method of this embodiment:
FIG. 3 is an explanatory diagram showing a configuration for supplying ink to the ejection head 32. The configuration for supplying ink to the ejection head 32 according to the present embodiment is roughly configured by an ink supply unit 60 and an internal mechanism of the head unit 30. As described above, the head unit 30 of this embodiment includes a plurality of ejection heads 3 for ejecting four different colors of ink.
2 is provided (see FIG. 2), but here to avoid the complexity of the figure,
Only an ejection head 32 that ejects certain ink (for example, K ink) and a configuration for supplying ink to these ejection heads 32 are shown.

The ink supply unit 60 is provided with an ink cartridge 62 and a pressure pump 64 for supplying the ink in the ink cartridge 62 to the head unit 30. An ink cartridge 61 made of aluminum containing ink is provided in the ink cartridge 62, and the ink pack 61 is connected to the head unit 30 via an ink supply channel 65. The pressure pump 64 is provided with a compression member 63, and the compression member 63 is driven by the air pressure generated by the pressure pump 64 to compress the ink pack 61 from the side surface. Therefore, when the pressure pump 64 is operated, the ink is supplied to the head unit 30 through the ink supply flow path 65 by the pressure with which the ink pack 61 is compressed by the compression member 63.

The ink supply flow path 65 connected to the head unit 30 is branched into a plurality of flow paths in the head unit 30, and the branched ink supply flow path 65 adjusts the ink supply pressure to the ejection head 32. The pressure adjusting valve 90 is connected to the ejection head 32. In the line printer 1 of the present embodiment, a bypass channel 66 that bypasses the pressure adjustment valve 90 is provided before the ink supply channel 65 is connected to the pressure adjustment valve 90. ,
It is connected to the ejection head 32 via the on-off valve 36. The reason why the bypass channel 66 is provided will be described in detail later.

Here, in the line printer 1 of the present embodiment, the ink supply pressure to the ejection head 32 is adjusted by the pressure adjustment valve 90 for the following reason. That is, in this embodiment, the ink is supplied from each ink cartridge 62 to the ejection head 32 via the ink supply flow path 65, and one ink supply flow path 65 is branched to form a plurality of ejection heads. Therefore, in the ink supply flow path 65 at the branch destination, the pressure of the ink greatly changes due to the flow path resistance in the ink supply flow path 65 before the branch. as a result,
A pressure supply system that pressurizes the ink pack 61 of the ink cartridge 62 and supplies the ink may be lower than the lower limit value of the ink supply pressure necessary to normally eject ink from the ejection head 32. Adopted. In such an ink pressure supply system, since the pressurized liquid is supplied to the ejection head 32, it is possible to maintain the ink supply pressure, but the pressure is transmitted to the ejection head 32 as it is. As a result, the ink cannot be ejected normally, or in some cases, the ink flows out from the ejection nozzle. Therefore, a pressure regulating valve 90 is provided for the purpose of preventing such problems.

Further, since the ejection head 32 is disposed at a different position of the head unit 30 (see FIG. 2), the length of the flow path until the ink supply flow path 65 reaches the ejection head 32 is determined by the ejection head 32. Each may be different. In this case, the ink supply pressure to the ejection head 32 varies due to the difference in pressure loss when the ink flows through the ink supply flow path 65. Since the ejection head 32 ejects the liquid by pressurizing the liquid, if the ink supply pressure to the ejection head 32 cannot be kept constant, the ink ejection amount of the ejection head 32 varies. As a result, the print image quality is degraded. For this reason, in the line printer 1 of this embodiment, the pressure of the ink supply to the ejection head 32 is kept constant by using the pressure adjustment valve 90. In the following, a structure for the pressure adjusting valve 90 to keep the ink supply pressure to the ejection head 32 constant will be described.

FIG. 4 is an explanatory view showing a detailed structure of the pressure regulating valve 90. In FIG. 4, the internal structure of the pressure regulating valve 90 is shown by taking a longitudinal section passing through the center of the pressure regulating valve 90.

The pressure regulating valve 90 of this embodiment is provided with two spaces for storing ink. That is, a pressure chamber 91 connected to the ejection head 32 is provided above the pressure adjustment valve 90, and a front chamber 92 connected to the ink cartridge 62 is provided below the valve. A narrow passage penetrates the partition wall separating the pressure chamber 91 and the front chamber 92, and a passage shaft 93 having the same diameter as the passage is slidably provided in the passage. . Two passage grooves 94 are provided on the side surface of the passage shaft 93, and one end of the passage groove 94 opens to the pressure chamber 91 side, and the other end opens to the front chamber 92 side.

A base member 95 is fixed to the end of the passage shaft 93 on the pressure chamber 91 side, and the base member 95 is supported from the bottom side of the pressure chamber 91 by a support spring 96 provided so as to surround the passage shaft 93. It is lifted to a certain height. Further, the base member 95 is bonded to a substantially central position of the thin film film 97 constituting one side surface (the upper surface side in FIG. 4) of the pressure chamber 91.

A rubber sealing valve 98 is provided at the end of the passage shaft 93 on the front chamber 92 side. The sealing valve 98 is pushed upward from the bottom surface side of the front chamber 92 by a sealing spring 99, and usually a protruding portion provided above the sealing valve 98 is pressed against the upper surface of the front chamber 92. Thus, the periphery of the passage shaft 93 is sealed from the front chamber 92 side.

FIG. 5 is an explanatory diagram showing an operation in which the pressure adjustment valve 90 adjusts the pressure at which ink is supplied to the ejection head 32. As described above, the pressure adjustment valve 90 is supplied with ink from the ink cartridge 62 via the ink supply channel 65 (see FIG. 3). At this time, ink is supplied to the front chamber 92 of the pressure adjusting valve 90 at a relatively high pressure by the pressing force of the pressurizing pump 64. Here, as described above with reference to FIG.
Since the periphery of the passage shaft 93 on the front chamber 92 side is hermetically sealed by the sealing valve 98 provided in FIG. 5, the front of the passage groove 94 provided in the passage shaft 93 as shown in FIG. The opening portion on the chamber 92 side is in a state where the connection with the front chamber 92 is cut off by the sealing valve 98. Therefore, in this state, ink is not supplied from the front chamber 92 to the pressure chamber 91 via the passage groove 94.

When ink is ejected from the ejecting head 32 in the state shown in FIG. 5A, the amount of ink in the ejecting head 32 decreases by the amount ejected, but the ink corresponding to the ejected amount is immediately pressurized by a predetermined pressure. Supplied from chamber 91. In addition, when ink is supplied from the pressure chamber 91 to the ejection head 32 in this way, the amount of ink in the pressure chamber 91 gradually decreases. At this time, FIG.
), The base film 95 provided with the film film 97 is also supported by the base film 95 provided with the film film 97 by pulling down the film film 97 constituting the upper surface of the pressure chamber 91 according to the volume change of the ink in the pressure chamber 91. It moves downward against the repulsive force of 96. Then, the passage shaft 93 fixed to the base member 95 also moves downward. As a result, the sealing valve 98 is opposed to the repulsive force of the sealing spring 99 by the end of the passage shaft 93 on the front chamber 92 side. Pushed down.

When the sealing valve 98 is pushed downward, the protruding portion of the sealing valve 98 that is in close contact with the upper surface of the front chamber 92 is separated from the upper surface, so that the passage groove 94 provided in the passage shaft 93 on the front chamber 92 side. The opening portion can be connected to the front chamber 92. As a result, as shown in FIG. 5C, the pressurized ink is supplied from the front chamber 92 to the pressure chamber 91 through the passage groove 94.

When ink is supplied to the pressure chamber 91 in this way, the amount of ink in the pressure chamber 91 increases, and accordingly, the base member 95 rises to the original height together with the film film 97. Accordingly, the passage shaft 93 also rises. As a result, as shown in FIG. 5A, the periphery of the passage shaft 93 on the front chamber 92 side is sealed again by the sealing valve 98, and the pressure chamber is separated from the front chamber 92. The supply of ink to 91 ends.

As described above, in the pressure regulating valve 90, the sealing valve 98 is normally closed. However, when the ink supply pressure in the pressure chamber 91 is reduced due to the ink amount in the pressure chamber 91 being smaller than a predetermined amount. The sealing valve 98 is temporarily opened. As a result, a small amount of pressurized ink is supplied from the front chamber 92, and the ink supply pressure in the pressure chamber 91 is restored. As a result, the supply pressure of the ink in the pressure chamber 91 is maintained in a predetermined pressure range lower than the pressure upstream of the front chamber 92, so that the pressure for supplying ink to the ejection head 32 can be kept constant. It is possible. In the line printer 1 provided with such a pressure regulating valve 90, the ink supply pressure to the ejection head 32 is kept constant, so that variations in the ink ejection amount can be suppressed.

Here, as described above, in the line printer 1 of the present embodiment, as a maintenance operation when the properties of the ink deteriorate in the ejection head 32, the pressure cleaning (the ejection head 3) is performed.
The operation of discharging the deteriorated ink in the ejection head 32 by pressurizing the inside 2) is adopted. However, a pressure adjustment valve 90 is provided on the upstream side of the ejection head 32, and the pressure adjustment valve 90 reduces the pressure of the ink supplied from the upstream to a predetermined pressure range and supplies it to the ejection head 32. (Refer to FIG. 4) The pressure cleaning that discharges the ink of the ejection head 32 using the pressure of the pressurized ink cannot be performed via the pressure adjustment valve 90. Therefore, in the line printer 1 of the present embodiment, the pressure cleaning is executed by the following method.

FIG. 6 is an explanatory diagram showing a method in which the line printer 1 of this embodiment executes pressure cleaning. 6A shows the internal mechanism of the head unit 30 when ink is ejected from the ejection head 32, and FIG. 6B shows the result of pressure cleaning. The state of the internal mechanism of the head unit 30 during the operation is shown.

As described above, in the line printer 1 of the present embodiment, the bypass channel 66 that bypasses the pressure regulating valve 90 is provided from the ink supply channel 65 in the head unit 30, and the bypass channel 66 is opened and closed. It is connected to the ejection head 32 via a valve 36 (see FIG. 3).
The on-off valve 36 of the bypass channel 66 is normally in a closed state including the time when the ink is ejected from the ejection head 32, so that the head unit is pressurized with the pressurizing pump 64. Even if it is supplied to 30, the pressurized ink is not supplied to the tip of the bypass channel 66. Accordingly, as shown by a thick line in FIG. 6A, pressurized ink is supplied up to the upstream side of the pressure regulating valve 90. At this time, as described above, the ink supply pressure to the ejection head 32 is reduced to a predetermined range by the pressure adjustment valve 90.

On the other hand, when the ink properties deteriorate in the ejection head 32, first, the on-off valve 36 of the bypass flow path 66 described above is opened. This ensures a flow path that can bypass the pressure regulating valve 90 and supply ink directly to the ejection head 32. Subsequently, the pressure pump 64 is driven to supply the pressurized ink to the head unit 30. At this time, the pressure for pressurizing the ink may be the same as the pressure for ejecting ink from the ejection head 32 (about 20 kpa), or a higher pressure (30 kpa to 40 kpa) than for ejecting ink. ). Further, the on-off valve 36 of the bypass channel 66 may be opened while the pressurizing pump 64 is driven, or the start of driving of the pressurizing pump 64 and the opening of the on-off valve 36 may be performed simultaneously.

When the pressurized ink is supplied to the head unit 30 with the on-off valve 36 opened, the ink is ejected through the bypass passage 66 as shown by the thick line in FIG. 6B.
Flow into. In this way, the ejection head 3 is maintained while maintaining a high supply pressure of the pressurized ink.
2 is supplied with ink, the pressure in the ejection head 32 is increased. As a result, it is possible to perform pressure cleaning in which ink having deteriorated properties in the ejection head 32 is discharged from the ejection nozzle. When the ink having deteriorated properties is discharged, the on-off valve 36 of the bypass flow channel 66 is closed to shut off the flow path for supplying the ink to the ejection head 32 by bypassing the pressure adjustment valve 90 and the pressure pump. By stopping 64, the pressure cleaning is finished.

As described above, if the bypass flow path 66 capable of bypassing the pressure adjustment valve 90 and supplying ink directly to the ejection head 32 is provided, the pressure adjustment valve 90 is provided upstream of the ejection head 32. However, the pressure of the pressurized ink can be transmitted to the ejection head 32 as necessary. Accordingly, the pressure cleaning is executed while maintaining the original function of the pressure regulating valve 90, which maintains the ink supply pressure to the ejection head 32 by reducing the pressure of the pressurized ink. Is possible.

Here, as a method for allowing ink whose properties have deteriorated to be discharged out of the ejection head 32 while the pressure adjustment valve 90 is provided in the ejection head 32, the ink is sucked from the ejection nozzle instead of the pressure cleaning described above. It is also conceivable to employ suction cleaning, which is a maintenance operation. However, when performing suction cleaning, the cap 40 is attached to the ejection head 3.
2, a closed space must be formed between the cap 40 and the ejection head 32, and the cap 40 needs to be brought into contact with the nozzle surface of the ejection head 32. In particular, in a line printer 1 equipped with a plurality of ejection heads 32, a cap 40 may be provided for each ejection head 32 in preparation for suction cleaning, and the plurality of caps 40 are brought into contact with the exact position of the nozzle surface. That is not always easy.

On the other hand, if the pressure cleaning can be adopted by providing the bypass flow path 66 that bypasses the pressure regulating valve 90 as in the present embodiment, the ink discharged from the ejection head 32 can be removed by the cap 40. You just have to take it. Therefore, since it is not necessary to cover the nozzle surface of the ejection head 32 with the cap 40, the operation of bringing the cap 40 into contact with the nozzle surface as in the above-described suction cleaning can be omitted.

In the pressure cleaning of this embodiment, the pressure at which the pressure pump 64 supplies ink is
This is used as a pressure for pressurizing the inside of the ejection head 32. Therefore, it is not necessary to provide a dedicated pump for performing pressure cleaning. In addition, when performing pressure cleaning, it is possible to increase the ink discharge capability by pressure cleaning by supplying the ink under a higher pressure than when ejecting the ink.

C. Modified example:
In the line printer 1 of the above-described embodiment, it has been described that the pressure adjustment valve 90 that adjusts the supply pressure of the ink to the ejection head 32 is provided for each of the plurality of ejection heads 32.
However, the pressure regulating valve 90 may be provided as follows.

FIG. 7 is an explanatory diagram showing a configuration for supplying ink to the ejection head 32 by the line printer 1 according to a modified example. As shown in the drawing, in the modified line printer 1, only one pressure adjustment valve 90 is provided, and the ink supply flow path 65 that guides ink from the ink cartridge 62 has one pressure adjustment valve 90. Are connected to all the ejection heads 32. Further, from the upstream side of the pressure regulating valve 90, a bypass passage 66 that bypasses the pressure regulating valve 90.
When the on-off valve 36 of the bypass flow path 66 is closed, the pressure adjustment valve 90 keeps the ink supply pressure to the ejection head 32 constant, and when the on-off valve 36 is opened, the ejection head The pressurized ink can be guided to 32 to perform pressure cleaning. Further, at a position immediately upstream of each ejection head 32, a switching valve 38 capable of switching opening and closing of the ink supply channel 65 is provided. For this reason, it is possible to selectively perform pressure cleaning by opening the switching valve 38 corresponding to the ejection head 32 from which ink is to be discharged and performing pressure cleaning with the other switching valves 38 closed. It has become.

In the line printer 1 of such a modification, it is necessary to provide the switching valve 38 for selectively performing the pressure cleaning, while the number of the pressure regulating valves 90 can be reduced. Here, as described above, the pressure regulating valve 90 has a complicated structure in order to keep the pressure of the ink supplied to the ejection head 32 constant (see FIG. 4).
Compared with 0, the switching valve 38 has a simple structure for only opening and closing the flow path. Therefore, by reducing the number of installed pressure regulating valves 90, the configuration for the line printer 1 to supply ink to the ejection head 32 can be simplified.

As mentioned above, although the Example of this invention was described, this invention is not limited above,
The present invention can be implemented in various modes without departing from the gist thereof.

1 ... Line printer, 30 ... Head unit, 32 ... Ejecting head,
36 ... Open / close valve, 40 ... Cap, 50 ... Suction pump,
60 ... Ink supply section, 62 ... Ink cartridge, 64 ... Pressure pump,
65 ... Ink supply channel, 66 ... Bypass channel, 90 ... Pressure regulating valve,
91 ... Pressure chamber, 92 ... Front chamber, 93 ... Passage shaft,
94 ... passage groove, 97 ... film membrane, 98 ... sealing valve

Claims (2)

A liquid ejecting apparatus that ejects liquid from an ejection nozzle provided in an ejection head,
A liquid supply unit that pumps the liquid ejected from the ejection nozzle toward the ejection head via a liquid flow path ;
Pressure adjusting means provided in the liquid flow path between the liquid supply unit and the ejection head, and the pressure of the liquid between the pressure adjustment means and the ejection head is within a predetermined pressure range. Pressure regulating means having a pressure regulating valve that opens only when,
By opening a bypass passage connecting the upstream side and the downstream side of the pressure regulating valve and guiding the liquid pressure-fed from the liquid supply unit to the ejection head, the liquid in the ejection head is discharged from the ejection nozzle. And a pressure cleaning means for performing a cleaning operation. The liquid ejecting apparatus according to claim 1,
The liquid supply portion during the cleaning operation, at a pressure higher than the state not subjected to the cleaning operation, the liquid ejecting apparatus for pumping liquids.

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