JP2004188857A - Ink jet printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink jet printer which smoothly and stably transfers high-viscosity ink to a recording head. <P>SOLUTION: The ink jet printer (1) is comprised of the recording head (6), an ink storage section (13), an ink intermediate storage section (14), a transfer means (17), and a pressure maintaining mechanism (14). The recording head (6) ejects the high-viscosity ink which becomes low-viscous according to increase in temperature, by decreasing the viscosity of the ink and maintaining a low-viscosity state of the same. The ink storage section (13) stores therein the high-viscosity ink. The ink intermediate storage section (14) is arranged in a transfer passage of the high-viscosity ink, extending from the ink storage section (13) to the recording head (6), for temporarily storing therein the high-viscosity ink. The transfer means (17) forcedly transfers the high-viscosity ink in the ink storage section (13) to the ink intermediate storage section (14). The pressure maintaining mechanism (14) maintains the pressure applied to a liquid level in the ink intermediate storage section (14) in a state that is almost equal to the atmospheric pressure. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inkjet printer.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an image recording method, there is an ink jet printer that records an image by discharging ink from a recording head onto a transported recording medium.
Some ink jet printers have an intermediate tank for temporarily storing ink in the middle of an ink transfer path from an ink bag for storing ink to a recording head (for example, see Patent Document 1). By providing the intermediate tank, the intermediate tank functions as a damper for suppressing the transfer speed of the ink, so that the recording head does not discharge an excessive amount of ink.
Further, by arranging the ink bag at a position higher than the intermediate tank, when refilling the ink from the ink bag into the intermediate tank, the ink can be transferred by its own weight.
Further, by disposing the intermediate tank at a position lower than the recording head, an excessive amount of ink does not flow to the recording head.
[0003]
[Patent Document 1]
Japanese Patent No. 3219326
[0004]
[Problems to be solved by the invention]
However, when a high-viscosity ink is used, the ink does not easily flow in the self-weight drop method, the ink stagnates in the transfer path, and the ink can be smoothly transferred from the ink back to the intermediate tank and from the intermediate tank to the recording head. It was difficult.
In addition, since the viscosity of the high-viscosity ink changes depending on the ambient temperature, the transfer speed of the ink changes depending on the use environment, and it has been difficult to transfer the ink to the recording head in a stable state.
[0005]
Therefore, an object of the present invention is to provide an ink jet printer that can smoothly transfer a high-viscosity ink to a recording head in a stable state.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention according to claim 1 is a recording head that discharges a high-viscosity ink, which decreases in viscosity with a rise in temperature, in a reduced viscosity state, and an ink that stores the high-viscosity ink. An ink jet printer comprising: a storage section; and an ink intermediate storage section provided on a transfer path of high-viscosity ink from the ink storage section to the recording head, and temporarily storing high-viscosity ink. A transfer means for forcibly transferring the high-viscosity ink in the storage section to the ink intermediate storage section, and a pressure maintaining mechanism for maintaining the pressure applied to the liquid level in the ink intermediate storage section at a state substantially equal to the atmospheric pressure are provided. It is characterized by having.
[0007]
According to the first aspect of the present invention, the transfer means forcibly transfers the high-viscosity ink in the ink storage section to the ink intermediate storage section, so that the high-viscosity ink can be smoothly and stably maintained. Can be transported. Further, by providing the pressure maintaining mechanism, even if the ink having reduced viscosity is ejected from the recording head and the high-viscosity ink in the ink intermediate reservoir is reduced, the ink is applied to the liquid surface of the high-viscosity ink in the ink intermediate reservoir. The pressure is maintained at a state substantially equal to the atmospheric pressure. As a result, no negative pressure is applied to the ink intermediate storage section. Therefore, the high-viscosity ink in the ink intermediate reservoir can be smoothly and stably transferred to the recording head at a substantially constant pressure.
[0008]
According to a second aspect of the present invention, in the ink jet printer according to the first aspect, the ink reservoir and the ink intermediate reservoir are connected, and the high-viscosity ink in the ink reservoir is transferred to the ink intermediate reservoir. And an opening / closing valve for controlling the transfer of the high-viscosity ink to the ink intermediate storage section in the ink transfer path section.
[0009]
According to the invention described in claim 2, when the high-viscosity ink in the ink intermediate storage section is transferred to the recording head, the air pressure in the ink intermediate storage section decreases, so that the high-viscosity ink is not transferred to the recording head. By opening the opening / closing valve, the pressure in the ink intermediate reservoir can be returned to the atmospheric pressure, so that the high viscosity ink can be transferred to the recording head in a stable state by operating the opening / closing valve.
[0010]
A third aspect of the present invention is the ink jet printer according to the first or second aspect, further comprising a height adjusting unit that adjusts a height position of the ink intermediate storage unit with respect to the recording head.
[0011]
According to the third aspect of the present invention, the relative height of the ink intermediate storage portion with respect to the recording head is changed by the height adjusting means based on the amount of the reduced viscosity ink ejected from the recording head. This controls the ink back pressure. That is, only by changing the height of the ink intermediate storage portion with respect to the recording head by the height adjusting means, the ink back pressure is controlled by utilizing the head difference between the high-viscosity ink in the ink intermediate storage portion and the recording head. You. Specifically, the back pressure of the ink becomes zero by setting the height of the ink liquid level in the ink intermediate reservoir to the same height as that of the print head, and the height of the ink liquid is raised by making the height of the ink liquid level higher than the print head. The pressure becomes a positive pressure, and the ink back pressure becomes a negative pressure by making the height of the ink liquid level lower than that of the recording head.
Therefore, the control of the ink back pressure is simplified, and the cost is reduced. Further, since the ejection amount of the reduced viscosity ink ejected from the recording head at one time can be adjusted, an image can be printed on the recording medium with stable accuracy.
[0012]
According to a fourth aspect of the present invention, in the ink jet printer according to any one of the first to third aspects, the ink intermediate storage section is deformed when the interior thereof is going to be lower than the atmospheric pressure. The air pressure is maintained.
[0013]
According to the invention described in claim 4, when the high-viscosity ink in the ink intermediate storage section is transferred to the recording head and the interior of the ink intermediate storage section is going to be lower than the atmospheric pressure, the ink intermediate storage section becomes the recording head. With the transfer amount of the high-viscosity ink to the inside, the ink is deformed so as to maintain the internal atmospheric pressure. That is, since the ink intermediate storage unit plays the role of the pressure maintaining mechanism in the first aspect, the inside of the ink intermediate storage unit can be maintained at the atmospheric pressure without separately providing the pressure maintaining mechanism.
[0014]
The invention according to claim 5 is the inkjet printer according to any one of claims 1 to 4, wherein the high-viscosity ink has a viscosity at 30 ° C of 10 mPas to 500 mPas, and heats the high-viscosity ink. Heating means for controlling the heating means so as to heat the high-viscosity ink to 30 ° C. or more and 150 ° C. or less; and a high-viscosity ink heated based on the heating temperature control means. An ink discharge amount control unit for controlling the recording head so as to discharge the ink at 2 pL or more and 20 pL or less per dot.
[0015]
According to the invention as set forth in claim 5, by setting the viscosity of the high-viscosity ink at 30 ° C. to 10 mPas or more and 500 mPas or less, after the high-viscosity ink lands on the recording medium until it is irradiated with an active energy ray, It can be in close contact with the recording medium and can be appropriately leveled on the recording medium. This makes it possible to easily control the shape of the ink dots made of the high-viscosity ink that has landed on the recording medium to form a high-quality image, and to impart high strength to the image formed on the recording medium.
Further, the ink ejection amount control means controls the recording head so that the high viscosity ink heated to 30 ° C. or more and 150 ° C. or less by the heating means controlled by the heating temperature control means is ejected at 2 pL to 20 pL per dot. By doing so, it is possible to prevent ink clogging at the ejection port for ejecting the high-viscosity ink and to smoothly eject the high-viscosity ink. Therefore, a high-quality image can be formed with high efficiency.
[0016]
According to a sixth aspect of the present invention, in the ink jet printer according to any one of the first to fifth aspects, an ink amount detecting unit that detects an amount of the high-viscosity ink in the ink intermediate storage unit, and the ink amount detection. When the amount of the high-viscosity ink detected by the means is less than a predetermined value, the high-viscosity ink is supplied into the ink intermediate storage section, and the high-viscosity ink in the ink intermediate storage section is supplied during the supply of the high-viscosity ink. Ink supply control means for stopping supply of high-viscosity ink when the amount becomes equal to or more than a predetermined value.
[0017]
According to the invention described in claim 6, the ink amount detecting means detects the amount of the high-viscosity ink in the ink intermediate storage portion, and when the amount of the high-viscosity ink detected by the ink amount detecting means becomes less than a predetermined value. Then, the ink replenishment control means causes the high-viscosity ink to be replenished into the ink intermediate storage part. In addition, when the amount of the high-viscosity ink in the ink intermediate storage section becomes equal to or more than a predetermined value during the supply of the high-viscosity ink, the ink supply control means stops the supply of the high-viscosity ink.
Therefore, replenishment of the high-viscosity ink to the ink intermediate storage part can be automated, and the user's labor can be saved.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an inkjet printer according to an embodiment of the present invention will be described in detail with reference to the drawings.
First, an inkjet printer will be briefly described. In the inkjet printer according to the present embodiment, a high-viscosity ink having a viscosity at 30 ° C. of 10 mPas to 500 mPas is used. The high-viscosity ink is ejected from the recording head 6 (described later) to the recording medium 2 at a rate of 2 pL to 20 pL per dot in a state where the viscosity is reduced by heating at a temperature of 30 ° C. to 150 ° C.
As shown in FIG. 1, an inkjet printer 1 includes a recording unit 3 that discharges a high-viscosity ink (hereinafter, referred to as ink) to a recording medium 2 in a state where the viscosity is low, and performs image recording; And a guide section 4 for reciprocating the recording medium 2 in a main scanning direction orthogonal to a conveying direction (sub-scanning direction) in which the recording medium 2 is conveyed.
[0019]
The recording unit 3 has a carriage 5, and a plurality of recording heads 6 are mounted on the carriage 5.
[0020]
The carriage 5 is equipped with four recording heads 6 for ejecting inks of a plurality of colors, such as yellow, magenta, cyan, and black. Each recording head 6 has an ejection surface 7 facing the recording medium 2. A discharge port (not shown) for discharging the ink is formed. Ink supplied to the recording head 6 from an ink cartridge (not shown) or the like is charged into a nozzle (not shown) for discharging ink from a discharge port, and is discharged onto the recording medium 2 as necessary. ing.
[0021]
The carriage 5 is provided with an ultraviolet irradiation device 8 for irradiating the surface of the recording medium 2 on which the ink ejected from the recording head 6 has adhered with ultraviolet rays to cure and fix the surface. The ultraviolet irradiating device 8 is provided on both sides in the main scanning direction with respect to the recording head 6 provided on the carriage 5. It is provided so as to face. In addition, since the ultraviolet light emitted from the ultraviolet irradiation device 8 does not cure the ink on the ejection surface 7 and the ejection openings of the recording head 6, a light shielding plate 10 for regulating the irradiation direction of the ultraviolet light is attached to the irradiation surface 9. .
[0022]
The carriage 5 is capable of reciprocating along the guide portion 4, and is capable of moving the recording head 6 to a home position area where the moisturizing unit 11 is disposed, a recording area where ink is ejected to the recording medium 2, a nozzle missing of the recording head 6, and the like. Can be moved to the head maintenance area in which the maintenance unit 12 for eliminating the problem is disposed. When no image is recorded, the carriage 5 is located in the home position area.
[0023]
The recording head 6 is provided with a heating unit 25 (shown in FIG. 3) as heating means for heating the ink to 30 ° C. or more and 150 ° C. or less.
[0024]
Next, portions related to ink ejection in the present embodiment will be described.
As shown in FIG. 2, on the back side of the carriage 5, an ink bag 13 serving as an ink reservoir for storing ink, and ink transferred from the ink bag 13 to the recording head 6 is temporarily stored on the transfer path. An intermediate tank 14 serving as an ink intermediate storage unit, an ink tank 13 that connects the ink bag 13 and the intermediate tank 14, and a first ink transfer pipe 15 serving as an ink transfer path serving as an ink transfer path; And a recording head 6 and a second ink transfer pipe 16 serving as an ink transfer path. The ink bag 13 is arranged above the intermediate bag 14 and the recording head 6, and the intermediate tank 14 is arranged below the ink bag 13 and the recording head 6.
[0025]
A suction pump 17 for transferring the ink in the ink bag 13 to the intermediate tank 14 is provided near the outlet of the ink bag 13 in the first ink transfer pipe 15. An opening / closing valve 18 for controlling the transfer of ink to the intermediate tank 14 is provided near the inlet of the intermediate tank 14 in the first ink transfer pipe 15.
[0026]
The intermediate tank 14 is formed in a bag shape from a material that can be deformed when the internal pressure becomes lower than the atmospheric pressure, for example, polyethylene or the like, and the opening and closing valve 18 is closed to close the intermediate tank 14 and the second ink transfer space 16. The inside is sealed. As a result, even if the ink in the intermediate tank 14 is transferred to the recording head 6 and the pressure applied to the liquid surface of the ink in the intermediate tank 14 decreases, the intermediate tank 14 itself deforms and the atmospheric pressure is applied to the liquid surface. As a result, the intermediate tank 14 functions as a pressure maintaining mechanism.
[0027]
Further, the intermediate tank 14 includes an intermediate tank elevating device (not shown) as height adjusting means for adjusting the height position with respect to the recording head 6. As the intermediate tank lifting device, for example, an operation mechanism such as a device for moving the intermediate tank 14 in the vertical direction by a hydraulic cylinder or the like is preferable because it is simple. As described above, by changing the height position of the intermediate tank 14 with respect to the recording head 6, the pressure at which the ink is directed toward the recording head 6 can be adjusted. Further, the intermediate tank 14 is provided with an ink amount detection sensor 19 as an ink amount detecting means for detecting the amount of ink in the intermediate tank 14. The ink amount detection sensor 19 uses, for example, a known pressure sensor or the like, and is attached to the inner wall of the intermediate tank 14 at a height position where ink supply is required. When the liquid level of the ink falls below the position of the ink amount detection sensor 19 and the pressure from the ink is no longer detected, the opening / closing valve 18 is opened to supply the ink from the ink back 13.
[0028]
The open / close valve 18 is configured to enable the transfer of the ink to the intermediate tank 14 when the open / close valve 18 is in the open state, and to shut off the transfer of the ink to the intermediate tank 14 when the open / close valve 18 is in the closed state. It is used to prevent the ink in the tank 14 from flowing back to the first ink transfer pipe 15 and to return the inside of the intermediate tank 14 to atmospheric pressure when the pressure in the intermediate tank 14 becomes negative.
[0029]
As shown in FIG. 3, the suction pump 17, the open / close valve 18, the ink amount detection sensor 19, and the heating unit 25 are connected to a computer (not shown) via an interface 20, and are controlled by a control unit 21 of the computer. .
As shown in FIG. 3, the control unit 21 stores a CPU 22 that executes a system program and the like necessary for controlling each unit, a RAM 23 used as a work area of the CPU 22, a system program and the like executed by the CPU 22. A ROM 24 is provided.
[0030]
The CPU 22 reads out a program stored in the ROM 24, develops the program in the RAM 23, and controls an instruction to each unit based on the program.
Specifically, the CPU 22 functions as a heating temperature control unit that controls the heating unit 25 to heat the ink to 30 ° C. or more and 150 ° C. or less. Further, the CPU 22 functions as an ink discharge amount control unit that discharges the heated ink from the recording head 6 at 2 pL to 20 pL per dot. Further, when the amount of ink in the intermediate tank 14 detected by the ink amount detection sensor 19 becomes less than a predetermined value, the CPU 22 opens the open / close valve 18 to replenish the ink in the intermediate tank 14, During ink supply, when the amount of ink in the intermediate tank 14 becomes equal to or more than a predetermined value, the opening / closing valve 18 is closed to stop the ink supply.
[0031]
The RAM 23 forms a work area for the CPU 22 and has a memory area for temporarily storing image data under the control of the CPU 22.
[0032]
The ROM 24 stores programs for the CPU 22 to execute various functions.
Specifically, the ROM 24 includes a heating temperature control program for heating the ink to 30 ° C. or more and 150 ° C. or less, an ink ejection amount control program for ejecting the heated ink from the recording head 6 at 2 pL to 20 pL per dot, When the amount of ink in the intermediate tank 14 detected by the amount detection sensor 19 becomes less than a predetermined value, the open / close valve 18 is opened to supply ink into the intermediate tank 14. An ink supply control program for closing the open / close valve 18 and stopping the supply of ink when the amount of ink in the intermediate tank 14 becomes equal to or more than a predetermined value is provided.
[0033]
Next, an ink ejection operation process in the inkjet printer 10 configured as described above will be described with reference to the flowchart of FIG.
As shown in FIG. 4, the CPU 22 determines whether the amount of ink in the intermediate tank 14 is less than a predetermined value based on a detection signal from the ink amount detection sensor 19 (Step S1). Here, when a detection signal that the ink amount detection sensor 19 detects that the amount of ink in the intermediate tank 14 is less than the predetermined value is input to the CPU 22 (step S1; YES), the CPU 22 closes the open / close valve 18 It is detected whether or not there is (step S2). If the open / close valve 18 is closed (step S2; YES), the CPU 22 sends a signal to open the open / close valve 18 to the open / close valve 18, and opens the open / close valve 18 (step S3). If the open / close valve 18 is already open (step S2; NO), the process proceeds to step S4.
[0034]
Next, the CPU 22 detects whether or not the suction pump 17 is stopped (Step S4). Here, when the suction pump 17 is stopped (Step S4; YES), the CPU 22 transmits a signal for starting the suction pump 17 to the suction pump 17, and starts the suction pump 17 (Step S5). If the suction pump 17 has already been started (step S4; NO), the process proceeds to step S6.
In step S1, if the CPU 22 determines that the detection signal is not input from the ink amount detection sensor 19 and the ink in the intermediate tank 14 is equal to or more than the predetermined value (step S1; NO), the process proceeds to step S7. Move on.
[0035]
Next, in step S6, the CPU 22 determines whether or not the amount of ink in the intermediate tank 14 is equal to or greater than a predetermined value, based on whether or not a detection signal has been input from the ink amount detection sensor 19 (step S6). Here, if the CPU 22 determines that the amount of ink in the intermediate tank 14 is not equal to or more than the predetermined value based on the input of the detection signal from the ink amount detection sensor 19 (step S6; NO), the amount of ink in the intermediate tank 14 becomes equal to or more than the predetermined value. Until the determination in step S6 is repeated. When the detection signal is not input from the ink amount detection sensor 19 and the ink in the intermediate tank 14 is determined to be equal to or more than the predetermined value (step S6; YES), the CPU 22 detects whether the suction pump 17 is stopped. (Step S7). Here, when the suction pump 17 is driven (Step S7; NO), the CPU 22 transmits a signal to stop the suction pump 17 to the suction pump 17, and stops the suction pump 17 (Step S8). If the suction pump 17 has already stopped (step S7; YES), the process moves to step S9.
[0036]
Next, the CPU 22 detects whether or not the on-off valve 18 is closed (Step S9). If the open / close valve 18 is open (step S9; NO), the CPU 22 sends a signal to close the open / close valve 18 to the open / close valve 18 and closes the open / close valve 18 (step S10). If the open / close valve 18 is already closed (step S9; YES), the process proceeds to step S11.
[0037]
Next, the CPU 22 determines whether or not the image recording on the recording medium has been completed (Step S11). Here, if the image recording has been completed (step S11; YES), the ejection operation processing is terminated. If the image recording is being performed (step S11; NO), the process returns to step S1 again.
[0038]
According to the ink jet printer 1 of the present embodiment, since the suction pump 17 forcibly transfers the ink to the intermediate tank 14, the ink can be transferred smoothly and stably. Further, since the intermediate tank 14 is formed of a bag made of polyethylene or the like, even if the ink is ejected from the recording head 6 and the amount of ink in the intermediate tank 14 is reduced, the intermediate tank 14 is deformed, and thus the intermediate tank 14 is deformed. Is maintained at a state substantially equal to the atmospheric pressure. Thus, no negative pressure is applied to the intermediate tank 14. Therefore, the ink in the intermediate tank 14 can be smoothly and stably transferred to the recording head 6 at a substantially constant pressure.
[0039]
When the ink in the intermediate tank 14 is transferred to the recording head 6, the air pressure in the intermediate tank 14 decreases, so that the ink is not transferred to the recording head 6. Since the pressure in the chamber 14 can be returned to the atmospheric pressure, the ink can be transferred to the recording head 6 in a stable state by operating the opening / closing valve 18.
[0040]
Further, the ink back pressure is controlled by changing the relative height of the intermediate tank 14 with respect to the recording head 6 based on the amount of ink ejected from the recording head 6. That is, only by changing the height of the intermediate tank 14 with respect to the recording head 6, the ink back pressure is controlled using the head difference between the ink in the intermediate tank 14 and the recording head 6. Specifically, by setting the height of the ink liquid level in the intermediate tank 14 to be the same as that of the recording head 6, the ink back pressure becomes zero, and the height of the ink liquid level is set higher than that of the recording head 6. The ink back pressure becomes a positive pressure, and the ink back pressure becomes a negative pressure by making the height of the ink liquid level lower than that of the recording head 6.
Therefore, the control of the ink back pressure is simplified, and the cost is reduced. Further, since the ejection amount of ink ejected from the recording head 6 at one time can be adjusted, an image can be printed on a recording medium with stable accuracy.
[0041]
Further, when the ink in the intermediate tank 14 is transferred to the recording head 6 and the inside of the intermediate tank 14 is going to be lower than the atmospheric pressure, the intermediate tank 14 It deforms so as to maintain the atmospheric pressure inside the tank 14. That is, since the intermediate tank 14 itself serves as a pressure maintaining mechanism for eliminating a pressure difference between the inside and the outside of the intermediate tank 14, the liquid level of the ink in the intermediate tank 14 can be reduced without providing a separate pressure maintaining mechanism. Can be kept at atmospheric pressure.
[0042]
Further, by setting the viscosity of the ink at 30 ° C. to 10 mPas or more and 500 mPas or less, the ink adheres to the recording medium after it lands on the recording medium until it is irradiated with active energy rays, and the ink adheres to the recording medium. Can be moderately leveled. This makes it possible to easily control the shape of the ink dots made of the ink that has landed on the recording medium to form a high-quality image, and to impart high strength to the image formed on the recording medium.
The control unit 21 executes the heating temperature control program and the ink discharge amount control program so that the ink heated by the heating unit 25 to 30 ° C. or more and 150 ° C. or less is ejected at 2 pL or more and 20 pL or less per dot. Since the recording head 6 is controlled at the same time, it is possible to prevent high-viscosity ink from being clogged at a discharge port for discharging high-viscosity ink and smoothly discharge high-viscosity ink. Therefore, a high-quality image can be formed with high efficiency.
[0043]
Further, the ink amount detection sensor 19 detects the amount of ink in the intermediate tank 14, and when the amount of ink detected by the ink amount detection sensor 19 becomes smaller than a predetermined value, the CPU 22 executes the ink supply control program. Thus, the ink is supplied into the intermediate tank 14. In addition, when the amount of ink in the intermediate tank 14 becomes equal to or more than a predetermined value during the ink supply, the CPU 22 executes the ink supply control program to stop the ink supply.
Therefore, the replenishment of ink into the intermediate tank 14 can be automated, so that the user can save time and effort.
[0044]
Note that the present invention is not limited to the above embodiment. For example, when the intermediate tank 14 is formed of a strong material that does not deform due to a small pressure difference between the inside and the outside, a cock or the like that connects the inside of the intermediate tank 14 to the outside is provided, and the cock controls the pressure inside the intermediate tank 14. May be a mechanism that maintains the pressure at atmospheric pressure. The material of the intermediate tank 14 is not limited to polyethylene, but may be polypropylene, cellophane, or any other material that can be easily deformed when the inside of the intermediate tank 14 becomes lower than the atmospheric pressure. Further, the transfer means for transferring the ink from the ink bag 13 to the intermediate tank 14 is not limited to the suction pump 17 provided in the first ink transfer pipe 15, but may be a pressure feed pump provided at the position shown in FIG. In addition, the present invention can be freely changed and improved without departing from the gist of the invention.
[0045]
【The invention's effect】
According to the first aspect of the present invention, the transfer means forcibly transfers the high-viscosity ink in the ink storage section to the ink intermediate storage section, so that the high-viscosity ink can be smoothly and stably maintained. Can be transported. Further, by providing the pressure maintaining mechanism, even if the ink having reduced viscosity is ejected from the recording head and the high-viscosity ink in the ink intermediate reservoir is reduced, the ink is applied to the liquid surface of the high-viscosity ink in the ink intermediate reservoir. The pressure is maintained at a state substantially equal to the atmospheric pressure. As a result, no negative pressure is applied to the ink intermediate storage section. Therefore, the high-viscosity ink in the ink intermediate reservoir can be smoothly and stably transferred to the recording head at a substantially constant pressure.
[0046]
According to the invention described in claim 2, when the high-viscosity ink in the ink intermediate storage section is transferred to the recording head, the air pressure in the ink intermediate storage section decreases, so that the high-viscosity ink is not transferred to the recording head. By opening the opening / closing valve, the pressure in the ink intermediate reservoir can be returned to the atmospheric pressure, so that the high viscosity ink can be transferred to the recording head in a stable state by operating the opening / closing valve.
[0047]
According to the third aspect of the present invention, the relative height of the ink intermediate storage portion with respect to the recording head is changed by the height adjusting means based on the amount of the reduced viscosity ink ejected from the recording head. This controls the ink back pressure. That is, only by changing the height of the ink intermediate storage portion with respect to the recording head by the height adjusting means, the ink back pressure is controlled by utilizing the head difference between the high-viscosity ink in the ink intermediate storage portion and the recording head. You. Specifically, the back pressure of the ink becomes zero by setting the height of the ink liquid level in the ink intermediate reservoir to the same height as that of the print head, and the height of the ink liquid is raised by making the height of the ink liquid level higher than the print head. The pressure becomes a positive pressure, and the ink back pressure becomes a negative pressure by making the height of the ink liquid level lower than that of the recording head.
Therefore, the control of the ink back pressure is simplified, and the cost is reduced. Further, since the ejection amount of the reduced viscosity ink ejected from the recording head at one time can be adjusted, an image can be printed on the recording medium with stable accuracy.
[0048]
According to the invention described in claim 4, when the high-viscosity ink in the ink intermediate storage section is transferred to the recording head and the interior of the ink intermediate storage section is going to be lower than the atmospheric pressure, the ink intermediate storage section becomes the recording head. With the transfer amount of the high-viscosity ink to the inside, the ink is deformed so as to maintain the internal atmospheric pressure. That is, since the ink intermediate storage unit plays the role of the pressure maintaining mechanism in the first aspect, the inside of the ink intermediate storage unit can be maintained at the atmospheric pressure without separately providing the pressure maintaining mechanism.
[0049]
According to the invention as set forth in claim 5, by setting the viscosity of the high-viscosity ink at 30 ° C. to 10 mPas or more and 500 mPas or less, after the high-viscosity ink lands on the recording medium until it is irradiated with an active energy ray, It can be in close contact with the recording medium and can be appropriately leveled on the recording medium. This makes it possible to easily control the shape of the ink dots made of the high-viscosity ink that has landed on the recording medium to form a high-quality image, and to impart high strength to the image formed on the recording medium.
The ink ejection amount control means controls the recording head so that the high-viscosity ink heated to 30 ° C. or more and 150 ° C. or less by the heating means controlled by the heating temperature control means is ejected at 2 pL to 20 pL per dot. By doing so, it is possible to prevent ink clogging at the ejection port for ejecting the high-viscosity ink and to smoothly eject the high-viscosity ink. Therefore, a high-quality image can be formed with high efficiency.
[0050]
According to the invention described in claim 6, the ink amount detecting means detects the amount of the high-viscosity ink in the ink intermediate storage portion, and when the amount of the high-viscosity ink detected by the ink amount detecting means becomes less than a predetermined value. Then, the ink replenishment control means causes the high-viscosity ink to be replenished into the ink intermediate storage part. In addition, when the amount of the high-viscosity ink in the ink intermediate storage section becomes equal to or more than a predetermined value during the supply of the high-viscosity ink, the ink supply control means stops the supply of the high-viscosity ink.
Therefore, replenishment of the high-viscosity ink to the ink intermediate storage part can be automated, and the user's labor can be saved.
[Brief description of the drawings]
FIG. 1 is a schematic front view of an ink jet printer according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a part of the inkjet printer according to the embodiment of the present invention.
FIG. 3 is a block diagram of the ink jet printer according to the embodiment of the present invention.
FIG. 4 is a flowchart illustrating an operation of supplying ink to an intermediate tank of the inkjet printer according to the embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view of a part of another example of an inkjet printer according to an embodiment of the present invention.
[Explanation of symbols]
1 Inkjet printer
6 Recording head
13 Ink back (ink storage section)
14 Intermediate tank (intermediate ink reservoir, pressure maintaining mechanism)
15 First ink transfer pipe (ink transfer path)
17 Suction pump (transfer means)
18 Open / close valve
19 Ink amount detection sensor (ink amount detection means)
21 control unit (heating temperature control means, ink discharge amount control means, ink supply control means)
25 heating unit (heating means)

Claims (6)

A recording head that discharges high-viscosity ink, which decreases in viscosity with a rise in temperature, in a reduced viscosity state,
An ink storage unit for storing the high-viscosity ink,
An ink intermediate storage unit that is provided on a transfer path of the high-viscosity ink from the ink storage unit to the recording head and temporarily stores the high-viscosity ink;
An inkjet printer comprising:
Transfer means for forcibly transferring the high-viscosity ink in the ink storage section to the ink intermediate storage section,
A pressure maintaining mechanism for maintaining the pressure applied to the liquid surface in the ink intermediate storage unit at a state substantially equal to the atmospheric pressure,
An ink jet printer comprising: The inkjet printer according to claim 1,
An ink transfer path unit that connects the ink storage unit and the ink intermediate storage unit, and serves as a transfer path when transferring high-viscosity ink in the ink storage unit to the ink intermediate storage unit,
An ink jet printer, comprising: an opening / closing valve for controlling the transfer of high-viscosity ink to the ink intermediate storage section in the ink transfer path section. The inkjet printer according to claim 1 or 2,
An ink jet printer comprising a height adjusting means for adjusting a height position of the intermediate ink storage section with respect to the recording head. The inkjet printer according to any one of claims 1 to 3,
An ink jet printer, wherein the intermediate ink storage section is configured to deform and maintain the atmospheric pressure when the inside of the ink intermediate storage section is going to be lower than the atmospheric pressure. The inkjet printer according to any one of claims 1 to 4,
The high-viscosity ink has a viscosity at 30 ° C. of 10 mPas or more and 500 mPas or less,
Heating means for heating the high-viscosity ink,
Heating temperature control means for controlling the heating means so as to heat the high-viscosity ink to 30 ° C. or more and 150 ° C. or less,
An ink ejection amount control unit that controls the recording head so that the high-viscosity ink heated based on the heating temperature control unit is ejected at 2 pL or more and 20 pL or less per dot;
An ink jet printer comprising: The inkjet printer according to any one of claims 1 to 5,
An ink amount detector for detecting an amount of the high-viscosity ink in the ink intermediate reservoir; and an ink amount detector in the ink intermediate reservoir when the amount of the high-viscosity ink detected by the ink amount detector becomes less than a predetermined value. Ink replenishment control means for replenishing the high-viscosity ink, and stopping replenishment of the high-viscosity ink when the amount of the high-viscosity ink in the ink intermediate storage portion becomes equal to or more than a predetermined value during replenishment of the high-viscosity ink;
An ink jet printer comprising:

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