JP6747453B2 - Inkjet recording device - Google Patents

Description

The present invention relates to an inkjet recording device.

2. Description of the Related Art Conventionally, there is an inkjet recording apparatus that includes a recording head provided with a nozzle that ejects ink, and records an image by ejecting ink from the nozzle of the recording head onto the recording medium while relatively moving the recording head and the recording medium. ..

The viscosity of the ink used in the inkjet recording device changes according to the temperature of the ink. Further, the amount and speed of the ink ejected from the nozzle depend on the viscosity of the ink, and if the viscosity of the ink is too high or too low, proper ink ejection may not be performed. On the other hand, conventionally, an ink temperature adjusting unit that heats or cools the ink is provided in the ink flow path through which the ink supplied to the recording head passes, and the ink whose temperature and viscosity are adjusted by the ink temperature adjusting unit is used as the recording head. There is a technique in which the ink is supplied to the recording head and the recording head ejects the ink appropriately (for example, Japanese Patent Application Laid-Open No. 2004-242242).

JP, 2009-178996, A

However, it is not easy to accurately adjust the temperature of the ink flowing in the ink flow path, and even if the temperature of the ink is adjusted accurately, the temperature of the ink flow path is not uniform. The temperature of the ink fluctuates before it flows into the. Therefore, the above-mentioned conventional technique has a problem that the temperature of the ink supplied to the recording head is not stable, and the ink having an improper temperature may be supplied to the recording head.

An object of the present invention is to provide an inkjet recording device that can stabilize the temperature of ink supplied to a recording head.

In order to achieve the above object, the invention of an ink jet recording apparatus according to claim 1 is
A plurality of recording heads each having a nozzle for ejecting ink, and an ink flow path portion communicating with the nozzle,
An ink storage unit that stores ink supplied to the plurality of recording heads;
An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage unit so as to be within a predetermined temperature range;
An ink circulation path through which the ink stored in the ink storage section circulates, passing through the ink storage section and a common ink flow path section that communicates with the ink flow path sections of the plurality of recording heads,
A liquid-sending means for performing a liquid-sending operation in which the ink in the ink circulation path is caused to flow in a predetermined liquid-sending direction to circulate the ink in the ink storage section in the ink circulation path;
A liquid supply control means for causing the liquid supply means to perform the liquid supply operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the predetermined temperature range;
First ink temperature detecting means for detecting the temperature of the ink in the ink circulation path immediately before flowing into the ink storage portion;
Determination means for determining whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
Equipped with
The liquid delivery control means causes the liquid delivery means to perform the liquid delivery operation when the determination means determines that the temperature is out of the predetermined temperature range.
It is characterized a call.

According to a second aspect of the invention, in the ink jet recording apparatus according to claim 1,
A second ink temperature detecting means for detecting the temperature of the ink in the ink storage portion or the temperature of the ink immediately after flowing out from the ink storage portion in the ink circulation path,
The determining means determines whether or not the difference between the temperature detected by the first ink temperature detecting means and the temperature detected by the second ink temperature detecting means is within a predetermined reference difference,
The liquid delivery control means is characterized by causing the liquid delivery means to perform the liquid delivery operation when the determination means determines that the difference is larger than the reference difference.

The invention described in claim 3 is the ink jet recording apparatus according to claim 1 ,
When the determination unit determines that the temperature is within the predetermined temperature range, the plurality of recording heads eject ink onto a recording medium to record an image on the recording medium. It is characterized in that a recording control means for performing the operation is provided.

According to a fourth aspect of the invention, in the ink jet recording apparatus according to the third aspect ,
A second ink temperature detecting means for detecting the temperature of the ink in the ink storage portion or the temperature of the ink immediately after flowing out from the ink storage portion in the ink circulation path,
The determining means determines whether or not the difference between the temperature detected by the first ink temperature detecting means and the temperature detected by the second ink temperature detecting means is within a predetermined reference difference,
The recording control unit may include the plurality of recording heads when the determining unit determines that the temperature is within the predetermined temperature range and the difference is within the reference difference. It is characterized in that the recording operation is performed by.

The invention described in claim 5 is the ink jet recording apparatus according to claim 3 or 4 ,
A plurality of head temperature detecting means for detecting a temperature of a portion of each of the plurality of recording heads, the temperature being a temperature corresponding to the temperature of the ink in the ink flow path portion,
The recording control unit performs the recording operation by the plurality of recording heads by a drive signal in which at least one of a voltage amplitude and a voltage application time is corrected according to a temperature detected by each of the plurality of head temperature detection units. It is characterized by making it possible.

The invention described in claim 6 is the ink jet recording apparatus according to any one of claims 1 to 5 , wherein
The liquid delivery control unit is configured to gradually increase the amount of ink delivered per predetermined time as the difference between the temperature detected by the first ink temperature detection unit and the predetermined target temperature increases. It is characterized in that the liquid feeding operation is performed by means.

Invention of an ink jet recording apparatus according to claim 7,
A plurality of recording heads each having a nozzle for ejecting ink, and an ink flow path portion communicating with the nozzle,
An ink storage unit that stores ink supplied to the plurality of recording heads;
An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage unit so as to be within a predetermined temperature range;
An ink circulation path through which the ink stored in the ink storage section circulates, passing through the ink storage section and a common ink flow path section that communicates with the ink flow path sections of the plurality of recording heads,
A liquid-sending means for performing a liquid-sending operation in which the ink in the ink circulation path is caused to flow in a predetermined liquid-sending direction to circulate the ink in the ink storage section in the ink circulation path;
A liquid supply control means for causing the liquid supply means to perform the liquid supply operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the predetermined temperature range;
An inkjet recording device comprising:
The ink circulation path is provided between the common ink flow path section and the ink storage section in the liquid feeding direction, and passes through the ink flow path sections of the plurality of recording heads to the common ink flow path section and the common ink flow path section. A first branch flow passage portion communicating with the ink storage portion, and the ink flow passage portions of the plurality of recording heads provided between the common ink flow passage portion and the ink storage portion in the liquid feeding direction. A second branch flow passage portion that allows the common ink flow passage portion and the ink storage portion to communicate with each other without passing through;
The inkjet recording device is
A switching unit that is provided within the range from the common ink flow path section to the plurality of recording heads in the liquid feeding direction to open or close the first branch flow path section;
Switching control means for closing the first branch flow path portion by the switching means when the ink circulation in the ink circulation path by the liquid feeding operation is performed;
It is characterized by having.

The invention described in claim 8 is the ink jet recording apparatus according to claim 7,
First ink temperature detecting means for detecting the temperature of the ink in the ink circulation path immediately before flowing into the ink storage portion;
Determination means for determining whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
Equipped with
The liquid delivery control means causes the liquid delivery means to perform the liquid delivery operation when the determination means determines that the temperature is out of the predetermined temperature range.
It is characterized by
The invention described in claim 9 is the ink jet recording apparatus according to any one of claims 1 to 8,
A degassing unit provided in the ink circulation path for desorbing gas in the ink from the ink is characterized.

According to a tenth aspect of the invention, in the inkjet recording apparatus according to any one of the first to ninth aspects,
The member forming the ink circulation path is made of metal.

According to the present invention, there is an effect that the temperature of the ink supplied to the recording head can be more stabilized.

It is a figure which shows schematic structure of an inkjet recording device. It is a schematic diagram of a head unit when a head unit is seen from the side. FIG. 3 is a schematic view of a head unit when the head unit is viewed from the side of a conveyor belt. It is a schematic diagram showing a configuration of an ink supply mechanism. FIG. 3 is a block diagram showing a main functional configuration of the inkjet recording apparatus. 6 is a flowchart showing a control procedure of ink temperature adjustment processing. It is a flow chart which shows the control procedure of image recording processing.

Hereinafter, embodiments of an inkjet recording apparatus of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a schematic configuration of an inkjet recording apparatus 1 according to an embodiment of the present invention.
The inkjet recording device 1 includes a transport unit 10, a head unit 20, and the like.

The transport unit 10 includes a ring-shaped transport belt 103, the inner side of which is supported by two transport rollers 101 and 102 that rotate about a rotation axis extending in the X direction in FIG. 1. In the transport unit 10, the transport rollers 101 and 102 are rotated by a motor (not shown) while the recording medium P is placed on the transport surface of the transport belt 103, and the transport belt 103 circulates to move the recording medium P. The sheet is conveyed in the moving direction of the conveyor belt 103 (conveying direction; Y direction in FIG. 1).
Here, the recording medium P can be a sheet cut into a certain size. The recording medium P is supplied onto the conveyor belt 103 by a paper feeding device (not shown), and after the image is recorded, the recording medium P is ejected from the conveyor belt 103 to a predetermined paper ejection unit. Note that roll paper may be used as the recording medium P. In this case, the recording medium P is pulled out from the roll around which the recording medium P is wound and supplied onto the conveyor belt 103, and after the image is recorded, it is taken up by another roll. As the recording medium P, not only paper such as plain paper or coated paper, but also various media such as cloth or sheet-shaped resin capable of fixing the ink landed on the surface can be used.
The transport unit 10 of the present embodiment is configured to be able to transport a large recording medium P having a width in the X direction of about 2 m.

The head unit 20 discharges ink at appropriate timing on the recording medium P conveyed by the conveying unit 10 based on the image data to record an image. In the inkjet recording apparatus 1 of the present embodiment, four head units 20 respectively corresponding to four color inks of yellow (Y), magenta (M), cyan (C), and black (K) are arranged in the recording medium P conveyance direction. The colors Y, M, C, and K are arranged in order from the upstream side so as to be arranged at predetermined intervals. The number of head units 20 may be three or less or five or more.

FIG. 2A is a schematic diagram of the internal configuration when the head unit 20 is viewed from the side. FIG. 2B is a schematic diagram of the internal configuration when the head unit 20 is viewed from the side of the conveyor belt 103. The side view of the head unit 20 means a case where the head unit 20 is viewed from a direction parallel to the conveyance direction of the recording medium P at a position facing the head unit 20 on the conveyance surface of the conveyance belt 103. Say.

The head unit 20 has a plurality of recording heads 22 each provided with a plurality of recording elements 221 (FIG. 4) for ejecting ink. Each of the plurality of recording elements 221 includes a pressure chamber that stores ink, a piezoelectric element provided on the wall surface of the pressure chamber, and a nozzle 221n. Of these, the nozzle 221n ejects ink from an opening provided on the ink ejection surface of the recording head 22 that faces the conveyance surface of the conveyance belt 103. In the print head 22, a plurality of nozzles 221n are arranged in two rows in the X direction to form two nozzle rows, and these two nozzle rows are only half the arrangement interval of the nozzles 221n in the X direction. They are arranged in a mutually offset state.

In the head unit 20, as shown in FIG. 2B, a pair of recording heads 22 adjacent to each other in the Y direction are arranged in a staggered pattern at different positions in the X direction. In the head unit 20 of this embodiment, 24 pairs of recording heads are arranged in a zigzag pattern, and therefore 48 recording heads 22 are attached to the head unit 20. With such an arrangement of the recording head 22, the arrangement range of the nozzles 221n included in the head unit 20 in the X direction is the width of the area on the recording medium P conveyed by the conveyor belt 103 in which the image can be formed in the X direction. It is designed to cover. The head unit 20 is used in a fixed position when recording an image. That is, the inkjet recording apparatus 1 is an inkjet recording apparatus that performs single-pass system image recording using a line head.

As shown in FIG. 2A, the recording head 22 has a flow path portion 222 (ink flow path portion) that functions as an ink flow path in the print head 22, and an inlet 223 into which ink supplied to the flow path portion 222 flows. An outlet 224, through which the ink discharged from the flow path 222 flows, is provided. Of these, the flow path portion 222 communicates with the nozzle 221n via the pressure chamber.

The ink ejected from the nozzles 221n of the recording head 22 is liquid at room temperature. The amount and speed of the ink ejected from the nozzle 221n changes according to the viscosity of the ink. Also, the viscosity of the ink depends on the temperature. In this embodiment, an ink whose viscosity increases as the temperature lowers is used.

Each head unit 20 includes a print head drive unit 21 (FIG. 4) that drives the print head 22. The print head drive unit 21 supplies a drive circuit that supplies a voltage signal (hereinafter also referred to as a drive signal) having a drive waveform corresponding to image data to each print head 22, and an image at an appropriate timing for this drive circuit. A drive control circuit for supplying data. The drive circuit of the recording head drive unit 21 outputs a voltage signal having a drive waveform for deforming the piezoelectric element in accordance with the pixel value of the image data, and the recording element 221 applies the voltage signal to the piezoelectric element. Is configured. When a voltage signal having a drive waveform is applied to the piezoelectric element, the pressure chamber is deformed according to the voltage signal, the pressure inside the pressure chamber changes, and the ink ejection operation for ejecting ink from the nozzle 221n communicating with the pressure chamber is performed. Done. As a result, the amount of ink corresponding to the pixel value of the image data is ejected from the nozzle 221n. In the inkjet recording apparatus 1, by supplying a drive signal according to image data from the recording head drive unit 21 to each recording head 22, ink is ejected onto the recording medium P by the plurality of recording heads 22. A recording operation of recording an image on the recording medium P is performed.

As described above, since the viscosity of the ink varies depending on the temperature, even if the same drive signal is applied to the piezoelectric element, the amount and speed of the ejected ink vary depending on the temperature of the ink. In the inkjet recording apparatus 1 of the present embodiment, by correcting the magnitude of the voltage amplitude of the drive signal, fluctuations in the ejected ink amount and speed due to ink temperature fluctuations are suppressed. That is, the voltage amplitude is corrected to be larger as the ink temperature is lower and the ink viscosity is higher. The magnitude of the voltage amplitude can be corrected, for example, by changing the power supply voltage input to the drive circuit. Alternatively, the magnitude of the voltage amplitude may be corrected by inputting a plurality of different power supply voltages to the drive circuit and selecting the magnitude of the voltage signal output from the drive circuit from the different power supply voltages.
The voltage application time of the voltage signal may be changed instead of the voltage amplitude correction or in addition to the voltage amplitude correction. The voltage application time of the voltage signal can be corrected by changing the drive waveform pattern data referenced when the drive signal is output from the drive circuit. The voltage application time is corrected such that the voltage application time becomes longer as the ink temperature is lower and the ink viscosity is higher.

Further, the head unit 20 is provided so as to be movable in the X direction between a position facing the conveyor belt 103 and a position facing a cleaning unit (not shown). Under the control of the control unit 40, the head unit 20 moves to a position facing the transport belt 103 when performing an image recording operation, and moves to a position facing a cleaning unit when performing a discharge operation. Here, the discharging operation is to adjust the temperature of the recording head 22 by replacing the ink in the flow path portion 222 of the recording head 22 with the ink whose temperature is adjusted, or the ink liquid level (meniscus) of the nozzle 221n. This is an operation of ejecting ink from the recording head 22 to the ink receiving portion provided in the cleaning portion for the purpose of adjusting the above.

Next, an ink supply mechanism that supplies ink to the recording head 22 in the inkjet recording apparatus 1 will be described.

FIG. 3 is a schematic diagram showing the configuration of the ink supply mechanism 30.
In FIG. 3, the ink supply mechanism 30 related to one head unit 20 of the inkjet recording apparatus 1 is extracted and shown, but also in the other head units 20, the ink is supplied to the recording head 22 by the same ink supply mechanism 30. Is supplied. Further, in FIG. 3, the ink path is indicated by a thick solid line. Further, the ink feeding direction is indicated by an arrow.

The ink supply mechanism 30 includes a main tank 50 that stores ink, a sub tank 31 (ink storage unit) and an intermediate tank 33, an ink temperature adjusting unit 25 (ink temperature adjusting unit), and a first ink temperature detecting unit 24a (first). No. 1 ink temperature detecting means), a second ink temperature detecting section 24b (second ink temperature detecting means), a supply pump 51, a liquid feed pump 27 (liquid feed means), a deaeration device 60, The recording head 22, the ink flow paths 301, 302a, 302b, 303, 305a, 305b, 306, the common ink flow path part 304a, the common waste liquid flow path part 304b, the first valve 341 to the sixth valve 346, and the like. Prepare
The common ink flow passage portion 304a, the common waste liquid flow passage portion 304b, and the ink flow passages 301, 302a, 302b, 303, 305a, 305b, 306 are not particularly limited, but are formed by a hollow annular tube-shaped member. It is preferable to use metal so that the temperature of these members can be adjusted to a desired temperature in a shorter time.

The main tank 50 is provided outside the head unit 20 and stores ink of a color corresponding to the head unit 20. The ink stored in the main tank 50 is pumped out by the supply pump 51 that operates based on the control signal supplied from the CPU 41 (FIG. 4) and supplied to the sub tank 31 in the head unit 20.

The sub tank 31 stores the ink supplied from the main tank 50 and supplied to the recording head 22. In this embodiment, a metal container having a capacity of about 40 liters is used as the sub tank 31. The sub tank 31 communicates with the ink flow paths 301 and 306. The sub-tank 31 is a container opened to the outside, and is maintained at almost atmospheric pressure regardless of increase or decrease in the amount of ink.

In the vicinity of the sub tank 31 in the ink flow path 301, the second ink temperature detection for detecting the temperature of the ink immediately after flowing out from the sub tank 31 to the ink flow path 301 (hereinafter referred to as the second ink temperature T2). The portion 24b is provided. The vicinity of the sub tank 31 in this case refers to a range in which the temperature of the ink can be regarded as substantially the same as the temperature of the ink in the sub tank 31. Here, that the temperatures are substantially the same can mean that the temperature difference is within 1° C., for example.
The second ink temperature detection unit 24b has a temperature detection element such as a thermistor, and outputs data related to the second ink temperature T2 to the control unit 40 based on a control signal supplied from the CPU 41.

The ink temperature adjusting unit 25 includes a heating device 25a that heats the ink stored in the sub tank 31, and a cooling device 25b that cools the ink. The ink temperature adjusting unit 25 performs an ink temperature changing operation for changing the temperature of the ink in the sub tank 31 by heating by the heating device 25a or cooling by the cooling device 25b. The configurations of the heating device 25a and the cooling device 25b are not particularly limited, but for example, a system that is attached to the outside of the sub tank 31 to heat or cool the sub tank 31 to heat or cool the ink in the sub tank 31 is used. be able to. Alternatively, a system having a container communicating with the sub-tank 31 and heating or cooling the ink transferred from the sub-tank 31 to the sub-tank 31 and returning the ink to the sub-tank 31 may be used.
The ink temperature adjusting unit 25 performs an ink temperature variable movement operation based on a control signal supplied from the CPU 41 so that the temperature of the ink in the sub tank 31 approaches a target temperature within a predetermined temperature range described later. adjust. Here, the temperature of the ink in the sub tank 31 is detected as the second ink temperature T2 by the second ink temperature detection unit 24b. It should be noted that a temperature detection unit that detects the temperature of the ink in the sub tank 31 may be provided in the sub tank 31 separately from the second ink temperature detection unit 24b. In the present embodiment, the ink temperature adjusting unit 25 and the CPU 41 constitute an ink temperature adjusting unit.

The liquid feed pump 27 is provided in the ink flow path 301, and by applying pressure to the ink in the ink flow path 301, the ink is sent from the sub tank 31 to the common ink flow path portion 304 a via the ink flow path 301. The liquid is fed (liquid feeding operation). The configuration of the liquid feeding pump 27 is not particularly limited, but for example, a positive displacement pump such as a diaphragm pump or a tube pump that squeezes the tube with a roller to feed the liquid can be used. The liquid feed pump 27 operates under the control of the control unit 40.

The deaeration device 60 includes a deaeration module 32 (deaeration means) provided in the ink flow path 301, a chamber 521 connected to the deaeration module 32, a vacuum pump 52 connected to the chamber 521, and the like. The deaerator 60 deaerates the gas in the ink that has flowed into the deaerator module 32 from the sub tank 31 to desorb the gas from the ink.

The degassing module 32 and the chamber 521, and the chamber 521 and the vacuum pump 52 are connected by a vacuum tube, and a vacuum path from the degassing module 32 to the vacuum pump 52 is formed. The vacuum pump 52 performs a suction operation to set the pressure in the vacuum path to a predetermined negative pressure range lower than the atmospheric pressure, so that the gas is removed from the ink in the deaeration module 32, and the removed gas is removed. Flow through the vacuum path. The vacuum pump 52 does not necessarily need to bring the inside of the vacuum path to an ultra-high vacuum state, and decompresses to the extent necessary for deaeration. Further, the vacuum pump 52 operates based on a control signal supplied from the CPU 41.

The degassing module 32 is provided with a gas-permeable degassing film that allows gas to pass therethrough and does not allow liquid to pass therethrough. The ink flowing into the degassing module 32 is contacted with one surface of the degassing film, By sucking the gas with the vacuum pump 52, the gas in the ink is sucked into the vacuum path to be degassed. Although the structure of the degassing module 32 is not particularly limited, for example, the degassing module 32 has a large number of degassing membranes (hollow fiber membranes) having a hollow microfiber structure with one end closed, and the other end of the hollow fiber membrane The inside of the hollow fiber membrane can be decompressed by sucking gas from the side with the vacuum pump 52. In this state, when the ink contacts the membrane surface (outer surface) of the hollow fiber membrane, only the gas in the ink selectively permeates the membrane surface and is sucked into the hollow fiber membrane, and the ink is degassed. .. The degassing module 32 may have a configuration in which the outside of the hollow fiber membrane is decompressed and the gas in the ink passing through the inside of the hollow fiber membrane is desorbed to the outside of the hollow fiber membrane.

When not only gas but also liquid is sucked from the degassing module 32 and flows into the vacuum path, the chamber 521 separates the liquid from the gas, and the liquid is sucked by the vacuum pump 52, so that the vacuum pump 52 is operated. It is a trap that plays a role in preventing problems such as destruction. The chamber 521 is, for example, in the shape of a small tank, and the liquid is stored at the bottom of the chamber 521.

The ink deaerated by the deaeration module 32 is sent to the ink flow path 302a and the ink flow path 302b. Of these, the ink flow path 302a is provided with a first valve 341 that switches between opening and closing of the ink flow path 302a. Further, the ink flow path 302b is provided with a third valve 343 and a fourth valve 344 that switch between opening and closing of the ink flow path 302b. The first valve 341, the third valve 343, and the fourth valve 344 are valves that open and close to open or close the ink flow path according to the input of a predetermined valve drive signal, and for example, solenoid valves are used. The same applies to the configurations of the second valve 342, the fifth valve 345, and the sixth valve 346.

The intermediate tank 33 is arranged between the third valve 343 and the fourth valve 344 of the ink flow path 302b. The intermediate tank 33 is a small ink chamber that temporarily stores the ink to be supplied to the recording head 22, and is sealed except for the connection point with the ink flow path 302b. In this embodiment, a metal container having a capacity of about 1 liter is used as the intermediate tank 33.
The ink flow path 302a and the ink flow path 302b join the ink flow path 303.

The common ink channel portion 304a is a tubular member that communicates with the inlet 223 of each of the 48 recording heads 22 provided in the head unit 20 and the ink channels 303 and 305a. The ink just before being supplied to the recording head 22 is stored in the common ink flow path portion 304a.

In the ink flow path between the common ink flow path portion 304 a and the recording head 22, there is one fifth valve 345 (switching unit) for switching the opening and closing of the ink flow path, one for the pair of recording heads 22. , A total of 24 are provided. From the common ink flow path portion 304a, the ink flowing from the ink flow path 303 is supplied with the ink flowing from the ink flow path 303 in a state where the second valve 342 provided in the ink flow path 305a is opened and the fifth valve 345 is closed. Is sent to the ink flow path 305a in accordance with the liquid feeding operation by the. In addition, from the common ink flow path portion 304a, the ink that has flowed in from the ink flow path 303 with the second valve 342 closed and the fifth valve 345 opened is supplied by the liquid supply pump 27 or The ink is discharged to the flow path 222 through the inlet 223 of the recording head 22 according to the ink ejection operation of the recording head 22. The common ink flow passage portion 304a has a diameter larger than that of the ink flow passages 301, 302a, 302b, 303, 305a, 305b, 306 in order to suppress the pressure change in the tube due to the change of the outflow amount of ink to the recording head 22. The member having is used.

The recording head 22 is provided at a position where the position of the nozzle 221n is higher than the ink surface of the intermediate tank 33, the first valve 341 is closed, and the fourth valve 344 and the fifth valve 345 are opened. In the state, the ink in the recording head 22 is set to a negative pressure due to the head difference between the ink in the recording head 22 and the ink in the intermediate tank 33. As a result, unintended leakage of ink from the nozzle 221n that does not eject ink is suppressed.
In addition, in each recording head 22, a portion of the recording head 22 having a temperature corresponding to the temperature of the ink in the flow path portion 222 (for example, the ink of the flow path portion 222 such as a nozzle plate provided with an opening of the nozzle 221n). A head temperature detection unit 23 (head temperature detection means) for detecting a temperature of a portion (to which heat is transmitted) (hereinafter, also referred to as a head temperature Th) is attached. The head temperature detection unit 23 has a temperature detection element such as a thermistor, and outputs the detection result of the head temperature Th to the control unit 40 based on the control signal supplied from the CPU 41.

The common waste liquid flow passage portion 304b is a member having the same shape and material as the common ink flow passage portion 304a, and communicates with the outlet of each of the 48 recording heads 22 and the ink flow passage 305b. In the state where the sixth valve 346 provided in the ink flow path 305b is opened, the ink that has not been ejected by the nozzles 221n of the recording head 22 flows into the common waste liquid flow path 304b from the outlet 224 of the recording head 22. .. In addition, the ink that has flowed from the recording head 22 is sent from the common waste liquid flow path 304b to the ink flow path 305b in response to the liquid sending operation of the liquid sending pump 27.

The ink channel 305a is provided with a second valve 342 (switching unit) that switches between opening and closing of the ink channel 305a. Further, the ink flow path 305b is provided with a sixth valve 346 that switches between opening and closing of the ink flow path 305b. The ink flow passage 305a and the ink flow passage 305b join the ink flow passage 306. The ink flow path 306 communicates with the sub tank 31.

In the vicinity of the sub tank 31 in the ink flow path 306, a first ink temperature for detecting the temperature of the ink immediately before flowing into the sub tank 31 from the ink flow path 306 (hereinafter, referred to as the first ink temperature T1). A detector 24a is provided. The vicinity of the sub tank 31 in this case means a range in which the temperature of the ink is substantially the same as the temperature of the ink when flowing into the sub tank 31. Here, that the temperatures are substantially the same can mean that the temperature difference is within 1° C., for example.
The first ink temperature detection unit 24a has a temperature detection element such as a thermistor, and outputs data relating to the first ink temperature T1 to the control unit 40 based on a control signal supplied from the CPU 41.

In the ink supply mechanism 30, when the first valve 341 and the second valve 342 are opened and the third to sixth valves are closed (hereinafter, referred to as the first state), the ink stored in the sub tank 31 is stored. However, it circulates in an ink circulation path that passes through the ink flow paths 301, 302a and 303, the common ink flow path portion 304a, and the ink flow paths 305a and 306 according to the liquid supply operation by the liquid supply pump 27.

In the state where the second valve 342 is closed and the fifth valve 345 and the sixth valve 346 are opened in the first state (hereinafter referred to as the second state), the ink flow path in the ink circulation path is Instead of 305a, ink can be circulated in a path that passes through the flow path 222 of the recording head 22, the common waste liquid flow path 304b, and the ink flow path 305b. Here, the ink flow passage 305a constitutes a first branch flow passage portion, and the flow passage portion 222 of the recording head 22, the common waste liquid flow passage portion 304b and the ink flow passage 305b constitute a second branch flow passage portion. It
In this way, in the ink supply mechanism 30, the state in which the ink circulation path passes through the first branch flow channel portion and the state in which the ink circulation path passes through the second branch flow channel portion can be switched.

Further, in the state where the first valve 341 is closed and the third valve 343 and the fourth valve 344 are opened in the first state (hereinafter, referred to as a third state), the ink flow path 302a in the ink circulation path is described. Instead of this, it is possible to circulate the ink through a path that passes through the ink flow path 302b.

Further, in the state where the first valve 341, the second valve 342, and the sixth valve 346 are closed and the third to fifth valves are opened (hereinafter, referred to as the fourth state), they are stored in the sub tank 31. It is possible to supply the ink to the recording head 22 via the intermediate tank 33 and the common ink flow path portion 304a, and to generate the negative pressure of the ink in the recording head 22 due to the above-described head difference. In this embodiment, the discharging operation and the recording operation are performed in the fourth state.

FIG. 4 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1.
The inkjet recording apparatus 1 includes the above-described head unit 20, recording head driving unit 21, recording head 22, head temperature detecting unit 23, first ink temperature detecting unit 24a, second ink temperature detecting unit 24b, and ink temperature adjusting unit. 25, the liquid feed pump 27, the supply pump 51, the vacuum pump 52, the control unit 40, the electromagnetic valve drive unit 26, the transfer drive unit 53, the head unit movement drive unit 54, the operation display unit 55, and An output interface 56 and a bus 57 are provided. Of these, the control unit 40 includes a CPU 41 (Central Processing Unit) (ink temperature adjusting unit, liquid feeding control unit, determination unit, recording control unit, switching control unit), RAM 42 (Random unit).
An access memory), a ROM 43 (Read Only Memory), and a storage unit 44.

The CPU 41 reads out various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs to perform various arithmetic processes. The CPU 41 also controls the overall operation of the inkjet recording apparatus 1. For example, the CPU 41 operates the transport unit 10 and the head unit 20 based on the image data stored in the storage unit 44 to record an image on the recording medium P. Further, the CPU 41 operates each part of the ink supply mechanism 30 to circulate the ink in the ink circulation path, and also supplies the ink to the recording head 22.

The RAM 42 provides the CPU 41 with a working memory space and stores temporary data. The RAM 42 stores data indicating the setting of the pressure of the liquid feed pump. The RAM 42 may include a non-volatile memory.

The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like. The setting data includes table data in which the head temperature Th and the correction value of the voltage amplitude of the drive signal are stored in association with each other. Instead of the ROM 43, a rewritable non-volatile memory such as an EEPROM (Electrically Erasable Programmable Read Only Memory) or a flash memory may be used.

The storage unit 44 stores a print job (image recording command) input from the external device 2 via the input/output interface 56 and image data related to the print job. As the storage unit 44, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may be used together.

The solenoid valve drive unit 26 outputs a drive signal to each of the first valve 341 to the sixth valve 346 based on a control signal supplied from the CPU 41, so that each of the first valve 341 to the sixth valve 346 is independent. To open and close.

The transport drive unit 53 supplies a drive signal to a motor that drives the transport rollers 101 and 102 of the transport unit 10 based on a control signal supplied from the CPU 41 to rotate the transport belt 103 at a predetermined speed and timing.

The head unit movement drive unit 54 outputs a drive signal to a motor (not shown) based on a control signal supplied from the CPU 41, to move the head unit 20 to a position facing the transport belt 103 and a position facing the cleaning unit. Move in the X direction between.

The operation display unit 55 includes a display device such as a liquid crystal display or an organic EL display, and an input device such as a touch panel or an operation key arranged so as to be superimposed on the screen of the display device. The operation display unit 55 displays various kinds of information on the display device, converts the user's input operation on the input device into an operation signal, and outputs the operation signal to the control unit 40.

The input/output interface 56 mediates transmission/reception of data between the external device 2 and the control unit 40. The input/output interface 56 is composed of, for example, any of various serial interfaces, various parallel interfaces, or a combination thereof.

The bus 57 is a path for transmitting and receiving signals between the control unit 40 and other components.

The external device 2 is, for example, a personal computer, and supplies a print job, image data, and the like to the control unit 40 via the input/output interface 56.

Next, the ink temperature adjusting operation performed in the inkjet recording apparatus 1 will be described.

In the inkjet recording apparatus 1, since the ink is ejected from the nozzle 221n of the recording head 22 at an appropriate amount and speed, the temperature of the ink supplied to the recording head 22 is appropriately ejected before the image recording operation. Ink temperature adjustment operation is performed to adjust the temperature within a predetermined temperature range that can be achieved. In the present embodiment, the predetermined temperature range is set to a range of 5° C. (that is, 20° C. or more and 30° C. or less) on the plus side and the minus side of the target temperature Tc, with 25° C. as the target temperature Tc. Below, the lower limit of the temperature range will be referred to as lower limit temperature Tmin, and the upper limit will be referred to as upper limit temperature Tmax.

The inkjet recording apparatus 1 of the present embodiment is a large-sized apparatus that records an image on the recording medium P having a width of about 2 m, and each head unit 20 has an ink circulation path of 40 liters or more in the ink circulation path of the ink supply mechanism 30. Ink is stored and circulates. Most (90% or more) of the ink is stored in the sub tank 31. Therefore, when the temperature of the ink in the ink circulation path is out of the temperature range, for example, the ink is heated in the common ink flow path portion 304a in which the ink immediately before being supplied to the recording head 22 is stored. Alternatively, even if cooled, the ratio of the amount of heated or cooled ink to the amount of ink in the entire ink circulation path is small, so it takes time to adjust the temperature of ink in the entire ink circulation path. Further, in this case, until the temperature of the ink in the entire ink circulation path is adjusted, the ink having a temperature outside the appropriate temperature range sequentially flows into the common ink flow path portion 304a, so that the ink is heated or cooled each time. It is necessary to adjust the temperature. However, even if the ink flowing in the common ink flow path portion 304a is heated or cooled, high heating efficiency and cooling efficiency cannot be obtained, and it is not easy to adjust the flowing ink to a desired temperature.

Therefore, in the ink temperature adjusting operation of the present embodiment, the ink stored in the sub tank 31 is heated or cooled by the ink temperature adjusting unit 25, and the heated or cooled ink is circulated in the ink circulation path. As a result, the circulating ink serves as a heat medium, and the temperature of the constituent members of the ink circulation path and the temperature of the entire ink in the ink circulation path is adjusted to approach the target temperature Tc. Then, when the temperature of the ink that circulates in the ink circulation path and flows into the sub-tank 31 is within a predetermined temperature range including the target temperature Tc, the ink temperature adjustment operation is ended and the image is recorded on the recording medium P. The operation is started.

When the ink temperature adjustment operation is started, the first ink temperature detection unit 24a detects the first ink temperature T1. When the first ink temperature T1 is lower than the lower limit temperature Tmin, heating of the ink in the sub tank 31 by the heating device 25a of the ink temperature adjusting unit 25 is started. Further, the first valve 341 and the second valve 342 are opened, the third valve to the sixth valve are closed, the ink supply mechanism 30 is brought into the first state, and the liquid feeding operation by the liquid feeding pump 27 is started. This liquid feeding operation may be started after the temperature of the ink in the sub tank 31 is within the predetermined temperature range, or may be started before the temperature of the ink in the sub tank 31 is within the predetermined temperature range. May be done. As a result, the ink stored in the sub tank 31 and heated by the ink temperature adjusting unit 25 circulates in the ink circulation path that passes through the ink flow paths 301, 302a and 303, the common ink flow path section 304a, and the ink flow paths 305a and 306. ..

At a stage where the temperature of the entire ink circulation path is not sufficiently adjusted, the heat of the ink sent from the sub tank 31 is transmitted to the constituent members of the ink circulation path, and the temperature of the ink is kept flowing until it flows into the sub tank 31 again. Fall to. The ink that has flowed into the sub tank 31 is heated again by the ink temperature adjusting unit 25 and is sent out from the sub tank 31. By continuing the heating of the ink in the sub-tank 31 and the feeding of the ink in the ink circulation path in this way, heat is transferred from the circulating ink to the constituent members of the ink circulation path, and the temperature of the entire ink circulation path is increased. Will rise.

Therefore, immediately after the start of liquid supply of ink in the ink circulation path, the first ink temperature T1 detected by the first ink temperature detection unit 24a provided in the ink flow path 306 and the ink flow path 301 are provided. A difference ΔT is generated between the detected second ink temperature detection unit 24b and the second ink temperature T2, and the difference ΔT decreases as the ink feeding continues. Here, when the first ink temperature T1 is equal to or higher than the lower limit temperature Tmin and equal to or lower than the upper limit temperature Tmax, the temperature of the ink sent from the sub-tank 31 and traveling around the ink circulation path is within the predetermined temperature range. Therefore, it is determined that the temperature of the entire ink in the ink circulation path is adjusted within the predetermined temperature range. When the difference ΔT is within the predetermined reference difference ΔTa, it is determined that the temperature of the entire ink circulation path is in a substantially equilibrium state. Here, the reference difference ΔTa can be set to, for example, 2° C., but by setting it to a large value within a range in which the ink can be properly ejected by the recording head 22, the time for the ink temperature adjustment operation can be further shortened. ..
In the present embodiment, the liquid supply in the ink circulation path is continued until the first ink temperature T1 becomes equal to or higher than the lower limit temperature Tmin and equal to or lower than the upper limit temperature Tmax, and the difference ΔT becomes equal to or less than the reference difference ΔTa.

When the first ink temperature T1 is equal to or higher than the lower limit temperature Tmin and equal to or lower than the upper limit temperature Tmax, and the difference ΔT is within the reference difference ΔTa, the heating by the heating device 25a is ended. Further, the first valve 341 is closed, the third valve 343 and the fourth valve 344 are opened to bring the ink supply mechanism 30 into the third state, and the temperature-adjusted ink in the sub tank 31 flows through the ink flow path 302b. It passes through and is stored in the intermediate tank 33. As a result, the temperatures of the intermediate tank 33 and the ink flow path 302b are adjusted to be within the predetermined temperature range.
Here, the amount of ink stored in the intermediate tank 33 and the ink flow path 302b is sufficiently smaller than the amount of ink in the entire ink circulation path, and the heat capacity of the intermediate tank 33 and the ink flow path 302b is the same as that of the entire ink circulation path. Small enough for the heat capacity of. Therefore, the temperature drop in the entire ink circulation path due to the inflow of the ink into the intermediate tank 33 and the ink flow path 302b is very small, and can be ignored in the present embodiment.
When a predetermined amount of ink is stored in the intermediate tank 33, the liquid feeding operation by the liquid feeding pump 27 is stopped.

When the ink is stored in the intermediate tank 33, the second valve 342 is closed and the fifth valve is opened to put the ink supply mechanism 30 in the fourth state. Then, the head unit 20 is moved to a position facing the cleaning unit, and the above-mentioned discharging operation is performed. In this discharging operation, the ink in the flow path part 222 of the recording head 22 is ejected from the nozzle 221n to the ink receiving part, and the ink in the common ink flow path part 304a adjusted within the predetermined temperature range is discharged. It flows into the flow path 222. As a result, the temperature of the ink in the flow path portion 222 and the temperature of the portion of the recording head 22 to which the heat of the ink is transmitted are adjusted to be within the predetermined temperature range.
Here, the amount of ink stored in the recording head 22 is sufficiently smaller than the amount of ink in the entire ink circulation path, and the heat capacity of the recording head 22 is sufficiently smaller than the heat capacity of the entire ink circulation path. .. For this reason, the temperature drop in the entire ink circulation path due to the inflow of ink into the flow path portion 222 of the recording head 22 during the discharge operation is very small and can be ignored in the present embodiment.

When the nozzles 221n of the recording head 22 have ejected the ink a predetermined number of times, the ejection operation is ended. Then, the head unit 20 is moved to a position facing the transport belt 103, and the ink temperature adjusting operation ends. The discharge operation may be terminated when a predetermined time has elapsed in the case of discharging ink from the nozzles 221n at a predetermined frequency and performing the discharge operation. In addition, when the head temperature Th detected by the head temperature detection unit 23 becomes a temperature range that is equal to or higher than the lower limit temperature Tmin and equal to or lower than the upper limit temperature Tmax, or within a predetermined temperature range that is separately determined within the temperature range. Alternatively, the discharge operation may be ended.

In the above description, the case where the first ink temperature T1 detected by the first ink temperature detection unit 24a is lower than the lower limit temperature Tmin immediately after the start of the ink temperature adjustment operation has been described, but the first ink temperature T1 is the upper limit. When the temperature is higher than the temperature Tmax, the cooling device 25b cools the ink in the sub-tank 31, and the temperature is adjusted so that the temperature of the entire ink circulation path decreases.

Next, the ink temperature adjustment process performed by the CPU 41 in the ink temperature adjustment operation will be described with reference to a flowchart.

FIG. 5 is a flowchart showing the control procedure of the ink temperature adjustment processing.
In the ink temperature adjustment processing, image data of an image recorded on the recording medium P and an image recording command for instructing recording of the image are supplied from the external device 2 via the input/output interface 56 and stored in the storage unit 44. In this case, or when an input operation is performed on the operation display unit 55 by the user who gives an instruction to execute the ink temperature adjustment operation.

When the ink temperature adjustment process is started, the CPU 41 supplies a control signal to the first ink temperature detection unit 24a to detect the first ink temperature T1 and outputs the detection result to the control unit 40. Let Then, it is determined whether the first ink temperature T1 is lower than the lower limit temperature Tmin (step S101).

When it is determined that the first ink temperature T1 is lower than the lower limit temperature Tmin (“Yes” in step S101), the CPU 41 supplies a control signal to the solenoid valve drive unit 26 to cause the first valve 341 and the first valve 341 to operate. By opening the second valve 342 and closing the third valve 343 to the sixth valve 346, the ink supply mechanism 30 is brought into the first state (step S102).

The CPU 41 supplies a control signal to the ink temperature adjusting unit 25 to start heating the ink in the sub tank 31 by the heating device 25a (step S103).

The CPU 41 supplies a control signal to the liquid feed pump 27 to start liquid feed by the liquid feed pump 27 (step S104). As a result, the ink in the sub-tank 31 circulates in the ink circulation path that passes through the ink flow paths 301, 302a, 303, the common ink flow path portion 304a, and the ink flow paths 305a, 306. The process of step S104 may be executed before the process of step S103.

The CPU 41 supplies a control signal to the first ink temperature detection unit 24a and the second ink temperature detection unit 24b to detect the first ink temperature T1 and the second ink temperature T2, and controls the detection result. Output to the unit 40. The temperature condition is that the first ink temperature T1 is equal to or higher than the lower limit temperature Tmin and equal to or lower than the upper limit temperature Tmax, and the difference ΔT between the first ink temperature T1 and the second ink temperature T2 is equal to or lower than the reference difference ΔTa. It is determined whether or not it is satisfied (step S105). When it is determined that the temperature condition is not satisfied (“No” in step S105), the CPU 41 repeatedly executes the process of step S105 at predetermined time intervals.

When it is determined that the above temperature condition is satisfied (“Yes” in step S105), the CPU 41 supplies a control signal to the ink temperature adjusting unit 25 to cause the heating device 25a to control the ink in the sub tank 31. The heating is terminated (step S106).

The CPU 41 supplies a control signal to the solenoid valve drive unit 26 to close the first valve 341 and open the third valve 343 and the fourth valve 344 to put the ink supply mechanism 30 in the third state. As a result, the storage of ink in the intermediate tank 33 is started (step S107).

When a predetermined amount of ink is stored in the intermediate tank 33, the CPU 41 supplies a control signal to the liquid feed pump 27 to end the liquid feed by the liquid feed pump 27 (step S108).

The CPU 41 supplies a control signal to the solenoid valve drive unit 26 to close the second valve 342 and open all the fifth valves 345 to put the ink supply mechanism 30 in the fourth state (step S109).

The CPU 41 supplies a control signal to the head unit movement drive unit 54 to move the head unit 20 to a position facing the cleaning unit. Then, a control signal is supplied to the print head drive unit 21 to cause each print head 22 to perform the discharge operation (step S110). When ink is ejected from each nozzle 221n of the recording head 22 a predetermined number of times, the CPU 41 ends the ejection operation and moves the head unit 20 to a position facing the transport belt 103.

When it is determined in the process of step S101 that the first ink temperature T1 is equal to or higher than the lower limit temperature Tmin (“No” in step S101), the CPU 41 causes the first ink temperature T1 to be higher than the upper limit temperature Tmax. It is determined whether or not (step S111).

When it is determined that the first ink temperature T1 is higher than the upper limit temperature Tmax (“Yes” in step S111), the CPU 41 sequentially executes the processes from step S112 to step S116. Here, the processing of step S112, step S114, and step S115 is the same as the processing of step S102, step S104, and step S105, respectively. Further, in the process of step S113, the CPU 41 supplies a control signal to the ink temperature adjustment unit 25 to start cooling the ink in the sub tank 31 by the cooling device 25b. Further, in the processing of step S116, the CPU 41 supplies a control signal to the ink temperature adjusting unit 25, and ends the cooling of the ink in the sub tank 31 by the cooling device 25b. When the process of step S116 ends, the CPU 41 shifts the process to step S107.

When it is determined in step S111 that the first ink temperature T1 is lower than or equal to the upper limit temperature Tmax (“No” in step S111) or when the process of step S110 ends, the CPU 41 ends the ink temperature adjustment process.

FIG. 6 is a flowchart showing the control procedure of the image recording process.
The image recording process is started after the ink temperature adjustment process is completed when the image recording command is stored in the storage unit 44.

When the image recording process is started, the CPU 41 supplies a control signal to each head temperature detection unit 23 to detect the head temperature Th and outputs the detection result to the control unit 40 (step S201). ..

The CPU 41 sets the voltage correction value for each recording head 22 according to the head temperature Th corresponding to each recording head 22 (step S202). That is, the CPU 41 refers to the table data stored in the ROM 43, and acquires the voltage amplitude correction value corresponding to each head temperature Th acquired in step S201. Then, the correction value is set as a voltage correction value for each recording head 22 and stored in the storage unit 44.

The CPU 41 causes the recording heads 22 to record an image in accordance with the image data based on the voltage correction value set in step S202 (step S203). That is, the CPU 41 supplies a control signal to the transport driving unit 53 to rotate the transport rollers 101 and 102 of the transport unit 10 and move the transport belt 103 to transport the recording medium P. Then, the CPU 41 supplies the image data and the control signal to the print head drive unit 21, and causes the print head drive unit 21 to output the drive signal of the voltage correction value set in step S202 to the print head 22. An image is recorded on the recording medium P by ejecting ink from the nozzles 221n onto the recording medium P conveyed by the conveying section 10.

The CPU 41 determines whether or not an unexecuted image recording command is stored in the storage unit 44 (step S204). When it is determined that the unexecuted image recording command is recorded (“Yes” in step S204), the CPU 41 shifts the processing to step S201.
When it is determined that the unexecuted image recording command is not recorded (“No” in step S204), the CPU 41 ends the image recording process.

As described above, the inkjet recording apparatus 1 according to the present embodiment includes a plurality of recording heads 22 each having a nozzle 221n for ejecting ink and a flow path portion 222 communicating with the nozzle 221n, and a plurality of recording heads 22. A sub-tank 31 for storing the ink to be supplied, an ink temperature adjusting unit 25 and a CPU 41 for adjusting the temperature of the ink stored in the sub-tank 31 to fall within a predetermined temperature range, a sub-tank 31, and a plurality of recordings. An ink circulation path through which the ink stored in the sub tank 31 circulates through the common ink flow path portion 304a that communicates with the flow path portion 222 of the head 22, and the ink in the ink circulation path is caused to flow in a predetermined liquid feeding direction. And a liquid feed pump 27 that performs a liquid feed operation of circulating the ink in the sub tank 31 in the ink circulation path, and the CPU 41 sets the temperature of the ink in the ink circulation path to a target temperature Tc within a predetermined temperature range. The liquid-sending pump 27 causes the liquid-sending operation to be performed (liquid-sending control means). According to such a configuration, the ink heated or cooled in the sub-tank 31 serves as a heat medium to circulate in the ink circulation path, and heat is transferred between the ink and the constituent members of the ink circulation path. The temperature of the entire ink circulation path is adjusted. Therefore, the temperature of the ink supplied to the plurality of recording heads 22 can be made more stable as compared with the configuration in which the ink flowing in the ink flow path is heated or cooled. Further, since the ink stored and retained in the sub tank 31 is heated or cooled, the temperature of the ink can be adjusted more efficiently.

Further, the inkjet recording apparatus 1 includes a first ink temperature detection unit 24a that detects the temperature of the ink in the ink circulation path immediately before it flows into the sub tank 31, and the CPU 41 includes the first ink temperature detection unit 24a. It is determined whether or not the first ink temperature T1 detected by is within a predetermined temperature range (determination means), and it is determined that the first ink temperature T1 is outside the predetermined temperature range. In this case, the liquid feeding pump 27 performs the liquid feeding operation (liquid feeding control means). The ink immediately before flowing into the sub-tank 31 is the ink after heat is exchanged with the constituent members of the ink circulation path, and therefore the first ink temperature T1 of the ink is equal to the ink circulation path. The overall temperature is reflected. Therefore, according to the above configuration, it is determined that the temperature of the ink in the ink circulation path is out of the predetermined temperature range, and if the determination is made, the temperature of the ink in the ink circulation path is It can be adjusted so as to approach the target temperature Tc.

The ink jet recording apparatus 1 also includes a second ink temperature detection unit 24b that detects the temperature of the ink immediately after it has flowed out of the sub tank 31 in the ink circulation path, and the CPU 41 is detected by the first ink temperature detection unit 24a. It is determined whether the difference ΔT between the first ink temperature T1 and the second ink temperature T2 detected by the second ink temperature detection unit 24b is within a predetermined reference difference ΔTa (determination means), When it is determined that the difference ΔT is larger than the reference difference ΔTa, the liquid feed pump 27 causes the liquid feed operation (liquid feed control means). In the inkjet recording apparatus 1, the closer the temperature distribution of the ink circulation path is to uniform, the smaller the temperature fluctuation of the ink circulating in the ink circulation path, and the first ink temperature T1 becomes a value closer to the second ink temperature T2. As a result, the difference ΔT becomes smaller. Therefore, according to the above configuration, the ink temperature can be adjusted until the temperature distribution in the ink circulation path becomes substantially uniform. As a result, the temperature of the ink supplied to the recording head 22 can be further stabilized.

In addition, when it is determined that the first ink temperature T1 is within the predetermined temperature range, the CPU 41 ejects ink onto the recording medium P by the plurality of recording heads 22 and prints on the recording medium P. A recording operation for recording an image is performed (recording control means). As a result, the ink whose temperature and viscosity have been adjusted can be supplied to the recording head 22 to cause the recording head 22 to perform proper ink ejection. As a result, an image can be recorded with an appropriate image quality.

In addition, when it is determined that the first ink temperature T1 is within the predetermined temperature range and the difference ΔT is within the reference difference ΔTa, the CPU 41 causes the plurality of recording heads 22 to perform the recording operation. (Recording control means). With such a configuration, the recording operation by the recording head 22 can be started while the difference ΔT is within the reference difference ΔTa and the ink temperature is stable. As a result, the recording head 22 can stably and properly eject ink.

In addition, the inkjet recording apparatus 1 includes a plurality of head temperature detection units 23 that detect the temperatures of portions of each of the plurality of recording heads 22 that correspond to the temperature of the ink in the flow path 222, and the CPU 41 , The recording operation is performed by the plurality of recording heads 22 by the drive signal in which at least one of the voltage amplitude and the voltage application time is corrected according to the temperature detected by each of the plurality of head temperature detection units 23 (recording control unit). .. With such a configuration, proper ink ejection can be performed even when the ink temperature changes according to the operation of the recording element 221 in the recording head 22. As a result, it is possible to suppress deterioration in the image quality of the recorded image. Moreover, since the temperature of the ink supplied to the recording head 22 is adjusted within a predetermined temperature range in advance, the correction range of the voltage amplitude of the drive signal and the voltage application time can be reduced.

Further, the ink circulation path is provided between the common ink flow path portion 304a and the sub tank 31 in the liquid feeding direction and passes through the flow path portions 222 of the plurality of recording heads 22 to connect the common ink flow path portion 304a and the sub tank 31. The first branch flow passage portion that communicates with each other, and the common ink flow passage portion 304a provided between the common ink flow passage portion 304a and the sub tank 31 in the liquid feeding direction without passing through the flow passage portions 222 of the plurality of recording heads 22. The inkjet recording apparatus 1 is provided within the range from the common ink flow passage 304a to the plurality of recording heads 22 in the liquid feeding direction. The CPU 41 is provided with a fifth valve 345 that opens or closes the branch flow path part of the CPU 41. The CPU 41 uses the fifth valve 345 to make the first valve when the ink circulation in the ink circulation path is performed by the liquid feeding operation. The branch flow path part of is closed (switch control means). With such a configuration, it is possible to suppress the occurrence of the problem that the ink leaks from the nozzle 221n while the ink is circulating in the ink circulation path.

Further, the inkjet recording device 1 includes a degassing module 32 that is provided in the ink circulation path and that desorbs gas in the ink from the ink. As a result, the ink circulating in the ink circulation path can be degassed in parallel with the adjustment of the ink temperature.

The member forming the ink circulation path is metal. With such a configuration, the temperature of the member forming the ink circulation path can be efficiently adjusted by the heat of the circulating ink. As a result, the temperature of the ink circulation path can be adjusted in a shorter time.

(Modification)
Next, a modified example of the above embodiment will be described. The present modified example is different from the above-described embodiment in that the liquid feed amount of the liquid feed pump 27 per predetermined time is changed during the execution of the ink temperature adjustment operation. The differences from the above embodiment will be described below.

In the present modification, after the heating by the heating device 25a or the cooling by the cooling device 25b is started in the ink temperature adjusting operation, the first ink temperature detection unit 24a detects the first ink temperature T1 every predetermined time. .. Then, according to the difference between the detected first ink temperature T1 and the target temperature Tc, the liquid feed amount of the liquid feed pump 27 per predetermined time is changed. That is, the amount of liquid sent by the liquid sending pump 27 per predetermined time is changed so as to increase gradually as the difference between the first ink temperature T1 and the target temperature Tc increases. When the difference between the first ink temperature T1 and the predetermined target temperature Tc is less than or equal to a predetermined value, the liquid feeding pressure of the liquid feeding pump 27 is constant regardless of the magnitude of the difference. You may make it.

As described above, in the inkjet recording apparatus 1 according to the present modification, the CPU 41 determines that the difference between the first ink temperature T1 detected by the first ink temperature detection unit 24a and the target temperature Tc increases as the predetermined time elapses. The liquid-feeding pump 27 causes the liquid-feeding operation to be performed so as to gradually increase the liquid-feeding amount (ink-feeding control means). With such a configuration, as the difference between the first ink temperature T1 and the predetermined target temperature Tc is larger, the amount of ink passing through each part of the ink circulation path per unit time is increased, and the ink circulation path The amount of heat exchanged per unit time between each unit and the ink as the heat medium can be increased. As a result, the temperature of the ink circulation path can be adjusted within a predetermined temperature range in a shorter time.

The present invention is not limited to the above-mentioned embodiment and each modification, and various changes can be made.
For example, in the above-described embodiment and modification, the ink temperature adjusting unit 25 is described as an example including the heating device 25a and the cooling device 25b. However, for example, when the lower limit temperature Tmin is higher than the environmental temperature of the inkjet recording device 1. The ink temperature adjusting unit 25 may include only the heating device 25a. In addition, for example, when the upper limit temperature Tmax is lower than the environmental temperature of the inkjet recording apparatus 1, the ink temperature adjusting unit 25 may include only the cooling device 25b.

Further, in the above-described embodiment and modified example, both the determination as to whether or not the first ink temperature T1 is within a predetermined temperature range and the determination as to whether or not the difference ΔT is equal to or less than the reference difference ΔTa are performed. However, the present invention is not limited to this.
For example, when the temperature distribution in the ink circulation path does not greatly vary in the ink temperature adjusting operation, the determination as to whether the difference ΔT is the reference difference ΔTa or less may be omitted. In this case, the second ink temperature detection unit 24b may not be provided.
Furthermore, the ink temperature may be adjusted without determining whether or not the first ink temperature T1 is within a predetermined temperature range. In this case, for example, based on the operation temperature of the ink jet recording apparatus 1 and the preset operation settings of the ink temperature adjusting unit 25 and the liquid feed pump 27 in association with the elapsed time since the last ink temperature adjusting operation was performed. Ink temperature adjustment operation can be performed. In this case, the first ink temperature detector 24a may be omitted.

Further, in the above-described embodiment and modification, the ink flow paths 301, 302a, 302b, 303, 305a, 305b, 306, the common ink flow path portion 304a, the common waste liquid flow path portion 304b, the sub tank 31, and the intermediate tank 33 are made of metal. Although description has been made using the example of configuring, some or all of these may be configured by a material other than metal, for example, a resin such as a fluororesin or an epoxy resin. In this case, it is preferable to use a material having a lower specific heat and a higher thermal conductivity so that the temperature of the ink circulation path can be adjusted in a shorter time.

Further, in the above-described embodiments and modified examples, the example in which the ink in the sub-tank 31 is heated or cooled by the ink temperature adjusting unit 25 has been described, but in addition to the ink temperature adjusting unit 25, the ink flow paths 301, 302a, 302b, 303, 305a, 305b, 306, the common ink flow passage portion 304a, the common waste liquid flow passage portion 304b, and a part or all of the intermediate tank 33 are provided with a heating device and/or a cooling device for heating the ink passing therethrough. It may be provided.

Further, in the above-described embodiment and modification, the configuration in which the temperature of the ink immediately after flowing out from the sub tank 31 (second ink temperature T2) is detected by the second ink temperature detection unit 24b has been described as an example. Alternatively, the second ink temperature detection unit 24b may be provided inside the sub tank 31, and the temperature of the ink in the sub tank 31 may be detected as the second ink temperature T2.
Further, in the above-described embodiments and modified examples, the configuration in which the temperature of the ink immediately before flowing into the sub tank 31 (first ink temperature T1) is detected by the first ink temperature detection unit 24a has been described as an example. Instead, the first ink temperature detection unit 24a is provided in the sub-tank 31 in the vicinity of the portion where the ink flows from the ink flow passage 306, and the first ink temperature T1 is supplied from the ink flow passage 306 as the first ink temperature T1. The temperature of the ink before being mixed with the ink in the sub tank 31 may be detected.

Further, in the above-described embodiments and modified examples, an example in which the ink whose temperature has been adjusted is caused to flow into the flow path portion 222 of the recording head 22 by the discharging operation has been described, but the present invention is not limited to this. For example, instead of the discharge operation or before the discharge operation, the ink supply mechanism 30 is set to the second state, and the ink is circulated in the ink circulation path passing through the flow path 222 of the recording head 22. The temperature of 222 may be adjusted.

Further, in the above-described embodiments and modifications, the ink circulation path having the first and second branch flow paths has been described as an example, but the ink circulation path does not have the branch flow path and the ink circulation path is the recording head. It may be configured so as to pass through the flow path part.

Further, in the above-described embodiment and modification, an example is used in which the temperature of the ink is adjusted so that each of the plus side and the minus side of the target temperature Tc (25° C.) is within a range of 5° C. (20° C. to 30° C.). However, the temperature range on the plus side with respect to the target temperature Tc may be smaller than the temperature range on the minus side. For example, the temperature of the ink may be adjusted to be within the range of 20° C. to 26° C. by setting the temperature range on the minus side to 5° C. and the temperature range on the plus side to 1° C. with respect to the target temperature Tc. By doing so, it is possible to prevent the temperature of the ink from largely deviating from the target temperature Tc even if the temperature of the ink in the recording head 22 rises according to the operation frequency of the recording element 221.

Further, in the above-described embodiments and modified examples, an example in which ink that is liquid at room temperature is used has been described, but the present invention is not limited to this. For example, the present invention may be applied to an ink jet recording apparatus that heats and ejects a sol-like ink that is in the form of a gel when heated at room temperature into a sol.

Further, in the above-described embodiments and modifications, the single-pass type inkjet recording apparatus 1 has been described as an example, but the present invention may be applied to an inkjet recording apparatus that records an image while scanning the head unit. ..

Further, in the above-described embodiments and modified examples, the example in which the recording medium P is conveyed by the conveying unit 10 including the conveying belt 103 has been described, but the present invention is not limited to this, and the conveying unit 10 may rotate, for example, The recording medium P may be held and conveyed on the outer peripheral surface of the drum.

Although some embodiments of the present invention have been described, the scope of the present invention is not limited to the above-described embodiments, and includes the scope of the invention described in the claims and the equivalent scope thereof. ..

The present invention can be used for an inkjet recording device.

DESCRIPTION OF SYMBOLS 1 Inkjet recording device 2 External device 10 Conveying part 101,102 Conveying roller 103 Conveying belt 20 Head unit 21 Recording head drive part 22 Recording head 221 Recording element 221n Nozzle 222 Flow path part 223 Inlet 224 Outlet 23 Head temperature detecting part 24a 1st Ink temperature detection unit 24b Second ink temperature detection unit 25 Ink temperature adjustment unit 25a Heating device 25b Cooling device 26 Electromagnetic valve drive unit 27 Liquid feed pump 30 Ink supply mechanism 301, 302a, 302b, 303, 305a, 305b, 306 Ink flow passage 304a Common ink flow passage portion 304b Common waste liquid flow passage portion 31 Sub tank 32 Deaeration module 33 Intermediate tank 341 First valve 342 Second valve 343 Third valve 344 Fourth valve 345 Fifth valve 346 Sixth valve 40 Control Part 41 CPU
42 RAM
43 ROM
44 storage unit 50 main tank 51 supply pump 52 vacuum pump 521 chamber 53 transport drive unit 54 head unit movement drive unit 55 operation display unit 56 input/output interface 57 bus 60 deaerator P recording medium

Claims (10)

A plurality of recording heads each having a nozzle for ejecting ink, and an ink flow path portion communicating with the nozzle,
An ink storage unit that stores ink supplied to the plurality of recording heads;
An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage unit so as to be within a predetermined temperature range;
An ink circulation path through which the ink stored in the ink storage section circulates, passing through the ink storage section and a common ink flow path section that communicates with the ink flow path sections of the plurality of recording heads,
A liquid-sending means for performing a liquid-sending operation in which the ink in the ink circulation path is caused to flow in a predetermined liquid-sending direction to circulate the ink in the ink storage section in the ink circulation path;
A liquid supply control means for causing the liquid supply means to perform the liquid supply operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the predetermined temperature range;
First ink temperature detecting means for detecting the temperature of the ink in the ink circulation path immediately before flowing into the ink storage portion;
Determination means for determining whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
Equipped with
An ink jet recording apparatus , wherein the liquid feeding control unit causes the liquid feeding unit to perform the liquid feeding operation when the determination unit determines that the temperature is out of the predetermined temperature range. .. A second ink temperature detecting means for detecting the temperature of the ink in the ink storage portion or the temperature of the ink immediately after flowing out from the ink storage portion in the ink circulation path,
The determining means determines whether or not the difference between the temperature detected by the first ink temperature detecting means and the temperature detected by the second ink temperature detecting means is within a predetermined reference difference,
The liquid feed control means, the ink-jet recording according to claim 1, characterized in that to perform said liquid transfer operation by said feeding means when the difference is determined to be larger than the reference difference by said discrimination means apparatus. When the determination unit determines that the temperature is within the predetermined temperature range, the plurality of recording heads eject ink onto a recording medium to record an image on the recording medium. The inkjet recording apparatus according to claim 1 , further comprising recording control means for performing an operation. A second ink temperature detecting means for detecting the temperature of the ink in the ink storage portion or the temperature of the ink immediately after flowing out from the ink storage portion in the ink circulation path,
The determining means determines whether or not the difference between the temperature detected by the first ink temperature detecting means and the temperature detected by the second ink temperature detecting means is within a predetermined reference difference,
The recording control unit may include the plurality of recording heads when the determining unit determines that the temperature is within the predetermined temperature range and the difference is within the reference difference. The inkjet recording apparatus according to claim 3 , wherein the recording operation is performed by the following. A plurality of head temperature detecting means for detecting a temperature of a portion of each of the plurality of recording heads, the temperature being a temperature corresponding to the temperature of the ink in the ink flow path portion,
The recording control unit performs the recording operation by the plurality of recording heads by a drive signal in which at least one of a voltage amplitude and a voltage application time is corrected according to a temperature detected by each of the plurality of head temperature detection units. The inkjet recording apparatus according to claim 3 or 4 , wherein The liquid delivery control unit is configured to gradually increase the amount of ink delivered per predetermined time as the difference between the temperature detected by the first ink temperature detection unit and the predetermined target temperature increases. an ink jet recording apparatus according to any one of claims 1 to 5, characterized in that to perform said liquid transfer operation by means. A plurality of recording heads each having a nozzle for ejecting ink, and an ink flow path portion communicating with the nozzle,
An ink storage unit that stores ink supplied to the plurality of recording heads;
An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage unit so as to be within a predetermined temperature range;
An ink circulation path through which the ink stored in the ink storage section circulates, passing through the ink storage section and a common ink flow path section that communicates with the ink flow path sections of the plurality of recording heads,
A liquid-sending means for performing a liquid-sending operation in which the ink in the ink circulation path is caused to flow in a predetermined liquid-sending direction to circulate the ink in the ink storage section in the ink circulation path;
A liquid supply control means for causing the liquid supply means to perform the liquid supply operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the predetermined temperature range;
An inkjet recording device comprising:
The ink circulation path is provided between the common ink flow path section and the ink storage section in the liquid feeding direction, and passes through the ink flow path sections of the plurality of recording heads to the common ink flow path section and the common ink flow path section. A first branch flow passage portion communicating with the ink storage portion, and the ink flow passage portions of the plurality of recording heads provided between the common ink flow passage portion and the ink storage portion in the liquid feeding direction. A second branch flow passage portion that allows the common ink flow passage portion and the ink storage portion to communicate with each other without passing through;
The inkjet recording device is
A switching unit that is provided within the range from the common ink flow path section to the plurality of recording heads in the liquid feeding direction to open or close the first branch flow path section;
Switching control means for closing the first branch flow path portion by the switching means when the ink circulation in the ink circulation path by the liquid feeding operation is performed;
Features and to Louis inkjet recording apparatus that comprises a. First ink temperature detecting means for detecting the temperature of the ink in the ink circulation path immediately before flowing into the ink storage portion;
Determination means for determining whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
Equipped with
The liquid delivery control means causes the liquid delivery means to perform the liquid delivery operation when the determination means determines that the temperature is out of the predetermined temperature range.
The inkjet recording apparatus according to claim 7, wherein the inkjet recording apparatus is an inkjet recording apparatus. The ink jet recording apparatus according to claim 1, further comprising a degassing unit that is provided in the ink circulation path and that desorbs gas in the ink from the ink. The ink jet recording apparatus according to claim 1, wherein a member forming the ink circulation path is made of metal.

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