WO2017094518A1 - Inkjet recording device - Google Patents

Abstract

Provided is an inkjet recording device that can better stabilize the temperature of ink that is supplied to recording heads (22). The inkjet recording device comprises: a plurality of recording heads (22) that each have a nozzle that discharges ink and an ink flow path part that communicates with the nozzle; an ink storage part (31) that stores ink that is supplied to the plurality of recording heads (22); an ink-temperature adjustment means that adjusts the temperature of the ink stored in the ink storage part (31) to within a prescribed temperature range; an ink circulation path that passes through the ink storage part (31) and through a common ink flow path part (304a), which communicates with the ink flow path parts of the plurality of recording heads (22), and that circulates the ink stored in the ink storage part (31); a liquid delivery means (27) that performs a liquid delivery operation that makes the ink inside the ink circulation path flow in a prescribed liquid delivery direction and thereby makes the ink in the ink storage part (31) circulate through the ink circulation path; and a liquid delivery control means that makes the liquid delivery means perform the liquid delivery operation such that the temperature of the ink inside the ink circulation path approaches a prescribed target temperature that is within the prescribed temperature range.

Description

Inkjet recording device

The present invention relates to an ink jet recording apparatus.

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

The viscosity of the ink used in the ink jet recording apparatus changes according to the temperature of the ink. In addition, the amount and speed of the ink ejected from the nozzles depend on the viscosity of the ink. If the viscosity of the ink is too large or too small, proper ink ejection may not be performed. In contrast, conventionally, an ink temperature adjusting unit that heats or cools ink is provided in an ink flow path through which 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 printer and the ink is ejected appropriately by the recording head (for example, Patent Document 1).

JP 2009-178996 A

However, it is not easy to accurately adjust the temperature of the ink flowing through the ink flow path, and even if the temperature of the ink is accurately adjusted, if the temperature of the ink flow path is uneven, the recording head The ink temperature fluctuates before it flows into the ink. For this reason, the above-described conventional technique has a problem that the temperature of the ink supplied to the recording head is not stable, and ink at an inappropriate temperature may be supplied to the recording head.

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

In order to achieve the above object, the invention of the ink jet recording apparatus according to claim 1 comprises:
A plurality of recording heads each having a nozzle for ejecting ink and an ink flow path portion communicating with the nozzle;
An ink reservoir for storing ink to be supplied to the plurality of recording heads;
An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage section to be within a predetermined temperature range;
An ink circulation path through which the ink stored in the ink storage section circulates through the ink storage section and a common ink flow path section communicating with the ink flow path sections of the plurality of recording heads;
Liquid feeding means for performing a liquid feeding operation for causing the ink in the ink circulation path to flow in a predetermined liquid feeding direction and circulating the ink in the ink reservoir in the ink circulation path;
Liquid feeding control means for causing the liquid feeding means to perform the liquid feeding operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the range of the predetermined temperature range;
It is characterized by having.

According to a second aspect of the present invention, in the ink jet recording apparatus according to the first aspect,
First ink temperature detection means for detecting the temperature of ink immediately before flowing into the ink storage portion of the ink in the ink circulation path;
Discrimination means for discriminating whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
With
The liquid feeding control means is characterized in that the liquid feeding means performs the liquid feeding operation when the judging means judges that the temperature is out of the predetermined temperature range.

The invention according to claim 3 is the ink jet recording apparatus according to claim 2,
A second ink temperature detecting means for detecting the temperature of the ink in the ink reservoir or the temperature of the ink immediately after flowing out of the ink reservoir in the ink circulation path;
The determining means determines whether or not a 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 feeding control unit is configured to cause the liquid feeding unit to perform the liquid feeding operation when the discrimination unit determines that the difference is larger than the reference difference.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the second aspect,
Recording in which an image is recorded on the recording medium by ejecting ink to the recording medium by the plurality of recording heads when the temperature is determined to be within the predetermined temperature range by the determining means. It is characterized by comprising a recording control means for performing the operation.

The invention according to claim 5 is the ink jet recording apparatus according to claim 4,
A second ink temperature detecting means for detecting the temperature of the ink in the ink reservoir or the temperature of the ink immediately after flowing out of the ink reservoir in the ink circulation path;
The determining means determines whether or not a 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 plurality of recording heads when the recording control unit determines that the temperature is within the predetermined temperature range and the difference is within the reference difference by the determination unit. The recording operation is performed by the following.

The invention according to claim 6 is the inkjet recording apparatus according to claim 4 or 5,
A plurality of head temperature detection means for detecting the temperature of each of the plurality of recording heads, each of which is a temperature corresponding to the temperature of the ink in the ink flow path section;
The recording control means 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 the temperature detected by each of the plurality of head temperature detecting means. It is characterized by

The invention described in claim 7 is the ink jet recording apparatus according to any one of claims 2 to 6,
The liquid feeding control means is configured to cause the liquid feeding amount to gradually increase as the difference between the temperature detected by the first ink temperature detecting means and the predetermined target temperature increases. The liquid feeding operation is performed by means.

The invention according to claim 8 is the inkjet recording apparatus according to any one of claims 1 to 7,
The ink circulation path is provided between the common ink flow path section and the ink storage section in the liquid feeding direction, passes through the ink flow path sections of the plurality of recording heads, and the common ink flow path section. A first branch channel that communicates with the ink reservoir, and the ink channels of the plurality of recording heads provided between the common ink channel and the ink reservoir in the liquid feeding direction. A second branch flow path portion that allows the common ink flow path portion and the ink storage portion to communicate with each other without passing through;
The ink jet recording apparatus
Switching means provided in a range from the common ink flow path portion to the plurality of recording heads in the liquid feeding direction to open or close the first branch flow path portion;
Switching control means for closing the first branch flow path portion by the switching means when ink circulation is performed in the ink circulation path by the liquid feeding operation;
It is characterized by having.

The invention according to claim 9 is the inkjet recording apparatus according to any one of claims 1 to 8,
It is provided with a deaeration means provided in the ink circulation path and desorbing a gas in the ink from the ink.

The invention according to claim 10 is the ink jet recording apparatus according to any one of claims 1 to 9,
The member constituting 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 further stabilized.

It is a figure which shows schematic structure of an inkjet recording device. It is the schematic of a head unit at the time of seeing a head unit from the side. It is the schematic of a head unit at the time of seeing a head unit from the conveyance belt side. It is a schematic diagram which shows the structure of an ink supply mechanism. It is a block diagram which shows the main function structures of an inkjet recording device. It is a flowchart which shows the control procedure of an ink temperature adjustment process. It is a flowchart which shows the control procedure of an image recording process.

Hereinafter, embodiments of the ink jet 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 ink jet recording apparatus 1 according to an embodiment of the present invention.
The ink jet recording apparatus 1 includes a transport unit 10 and a head unit 20.

The transport unit 10 includes a ring-shaped transport belt 103 that is supported on the inner side by two transport rollers 101 and 102 that rotate about a rotation shaft extending in the X direction in FIG. In the state where the recording medium P is placed on the conveyance surface of the conveyance belt 103, the conveyance unit 10 rotates the conveyance rollers 101 and 102 by a motor (not shown) so that the conveyance belt 103 rotates and moves the recording medium P. The conveying belt 103 is conveyed in the moving direction (conveying direction; Y direction in FIG. 1).
Here, the recording medium P can be a sheet cut to a certain size. The recording medium P is supplied onto the conveyance belt 103 by a paper feeding device (not shown), and after an image is recorded, the recording medium P is discharged from the conveyance belt 103 to a predetermined paper discharge unit. As the recording medium P, roll paper may be used. 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 conveying belt 103, and after the image is recorded, the recording medium P is wound up by another roll. As the recording medium P, in addition to paper such as plain paper and coated paper, various media capable of fixing ink landed on the surface, such as cloth or sheet-like resin, 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 records an image by ejecting ink at an appropriate timing on the recording medium P transported by the transport unit 10 based on the image data. In the inkjet recording apparatus 1 of the present embodiment, four head units 20 corresponding to four colors of ink of yellow (Y), magenta (M), cyan (C), and black (K) are transported in the recording medium P, respectively. They are arranged so as to be arranged at predetermined intervals in the order of Y, M, C, and K colors from the upstream side. 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 an internal configuration when the head unit 20 is viewed from the conveyance belt 103 side. Note that the case where the head unit 20 is viewed from the side refers to a case where the head unit 20 is viewed from a direction parallel to the transport direction of the recording medium P at a position facing the head unit 20 on the transport surface of the transport 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 for storing ink, a piezoelectric element provided on a wall surface of the pressure chamber, and a nozzle 221n. Among these, the nozzle 221n discharges ink from an opening provided on the ink discharge surface of the recording head 22 facing the conveyance surface of the conveyance belt 103. In the recording 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 one-half of the arrangement interval of the nozzles 221n in the X direction. They are arranged in a state shifted from each other.

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 manner at different positions in the X direction. In the head unit 20 of the present embodiment, 24 pairs of recording heads are arranged in a staggered manner, and therefore, 48 recording heads 22 are attached to the head unit 20. With such an arrangement of the recording heads 22, the arrangement range in the X direction of the nozzles 221n included in the head unit 20 is such that the width in the X direction of an area where an image can be formed in the recording medium P conveyed by the conveying belt 103. It comes to cover. The head unit 20 is used with its position fixed when recording an image. That is, the inkjet recording apparatus 1 is an inkjet recording apparatus that performs single-pass image recording using a line head.

As shown in FIG. 2A, the recording head 22 includes a flow path portion 222 (ink flow path portion) that functions as an ink flow path in the recording head 22, and an inlet 223 into which ink supplied to the flow path portion 222 flows. And an outlet 224 through which ink discharged from the flow path portion 222 flows out. Among these, the flow path part 222 is connected to 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 change according to the viscosity of the ink. Also, the viscosity of the ink depends on the temperature. In the present embodiment, ink whose viscosity increases with decreasing temperature is used.

Each head unit 20 includes a recording head drive unit 21 (FIG. 4) that drives the recording head 22. The recording head drive unit 21 supplies a drive waveform voltage signal (hereinafter also referred to as a drive signal) corresponding to the image data to each recording 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 according to the pixel value of the image data. The recording element 221 applies the voltage signal to the piezoelectric element. It is configured as follows. When a voltage signal having a driving waveform is applied to the piezoelectric element, the pressure chamber is deformed in accordance with the voltage signal, the pressure in the pressure chamber changes, and an ink discharge operation for discharging ink from the nozzle 221n communicating with the pressure chamber is performed. Done. As a result, an amount of ink corresponding to the pixel value of the image data is ejected from the nozzle 221n. In the ink jet recording apparatus 1, by supplying a drive signal corresponding to image data from the recording head driving 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 for 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 driving 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 ink jet 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 so as to increase as the ink temperature decreases and the ink viscosity increases. 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.
Instead of correcting the voltage amplitude or in addition to correcting the voltage amplitude, the voltage application time of the voltage signal may be changed. The voltage application time of the voltage signal can be corrected by changing drive waveform pattern data referred to when the drive signal is output from the drive circuit. The voltage application time is corrected so that the voltage application time becomes longer as the ink temperature is lower and the ink viscosity is higher.

The head unit 20 is provided so as to be movable in the X direction between a position facing the transport 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 conveyance belt 103 when performing an image recording operation, and moves to a position facing the cleaning unit when performing a discharge operation. Here, the discharging operation refers to adjusting 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 has been adjusted, or the ink 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 ink.

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 ink jet recording apparatus 1 is extracted and shown. However, in the other head units 20, ink is applied to the recording head 22 by the similar ink supply mechanism 30. Is supplied. In FIG. 3, the ink path is indicated by a thick solid line. In addition, the direction of ink feeding 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 adjustment unit 25 (ink temperature adjustment unit), and a first ink temperature detection unit 24a (first output). 1 ink temperature detection means), a second ink temperature detection unit 24b (second ink temperature detection 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 section 304a, the common waste liquid flow path section 304b, the first valve 341 to the sixth valve 346, and the like. Prepare.
The common ink flow path part 304a, the common waste liquid flow path part 304b, the ink flow paths 301, 302a, 302b, 303, 305a, 305b, and 306 are not particularly limited, but are formed by a member having a hollow annular tube shape. It is desirable that the metal member is made of 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 ink supplied from the main tank 50 and supplied to the recording head 22. In the present 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 substantially atmospheric pressure regardless of increase or decrease in the amount of ink.

A second ink temperature detection for detecting the temperature of ink immediately after flowing out of the sub tank 31 to the ink flow path 301 (hereinafter referred to as a second ink temperature T2) in the vicinity of the sub tank 31 in the ink flow path 301. A portion 24b is provided. The vicinity of the sub tank 31 in this case refers to a range in which the ink temperature can be regarded as substantially the same as the ink temperature in the sub tank 31. Here, it can be assumed that the temperature is substantially the same, for example, that the temperature difference is within 1 ° C.
The second ink temperature detection unit 24 b includes a temperature detection element such as a thermistor, for example, and outputs data related to the second ink temperature T <b> 2 to the control unit 40 based on a control signal supplied from the CPU 41.

The ink temperature adjustment 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 that changes 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. For example, the heating device 25a and the cooling device 25b that are attached to the outside of the sub tank 31 and heat or cool the sub tank 31 to heat or cool the ink in the sub tank 31 are used. be able to. Further, 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 container and returning it to the sub tank 31 may be used.
The ink temperature adjusting unit 25 performs the ink temperature changing operation based on the 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. Note 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 means.

The liquid feed pump 27 is provided in the ink flow path 301, and applies a pressure to the ink in the ink flow path 301, thereby feeding the ink from the sub tank 31 to the common ink flow path portion 304 a via the ink flow path 301. Liquid feeding (liquid feeding operation) is performed. The configuration of the liquid feed pump 27 is not particularly limited. For example, a volume transfer type pump such as a diaphragm pump or a tube pump that feeds liquid by squeezing a tube with a roller 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 (a deaeration unit) 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 deaeration device 60 performs deaeration to desorb the gas in the ink that has flowed from the sub tank 31 into the deaeration module 32 from the ink.

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

The deaeration module 32 is provided with a gas-permeable deaeration film that allows gas to pass but does not allow liquid to pass through. The ink that has flowed into the deaeration module 32 is brought into contact with one surface of the deaeration film, and the other side By sucking the gas with the vacuum pump 52, the gas in the ink is sucked into the vacuum path and degassed. The configuration of the deaeration module 32 is not particularly limited. For example, the deaeration module 32 has a large number of deaeration membranes (hollow fiber membranes) having a hollow fine fiber structure with one end blocked, and the other end of the hollow fiber membrane. The inside of the hollow fiber membrane can be depressurized by sucking gas from the side by 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 to degas the ink. . The deaeration 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.

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

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

An intermediate tank 33 is disposed 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 supplied to the recording head 22, and is sealed except for a connection portion with the ink flow path 302b. In the present embodiment, a metal container having a capacity of about 1 liter is used as the intermediate tank 33.
The ink flow path 302 a and the ink flow path 302 b merge with the ink flow path 303.

The common ink flow path portion 304a is a tube-shaped member that communicates with the inlets 223 of the 48 recording heads 22 provided in the head unit 20 and the ink flow paths 303 and 305a. The common ink channel 304 a stores ink immediately before being supplied to the recording head 22.

In the ink flow path between the common ink flow path portion 304 a and the recording head 22, a fifth valve 345 (switching means) that switches between opening and closing the ink flow path is provided for one pair of recording heads 22. A total of 24 are provided. In the state where the second valve 342 provided in the ink flow path 305a is opened and the fifth valve 345 is closed, the ink flowing from the ink flow path 303 is supplied from the common ink flow path portion 304a to the liquid feed pump 27. Is sent to the ink flow path 305a according to the liquid feeding operation. In addition, from the common ink channel portion 304a, the ink that has flowed from the ink channel 303 in a state where the second valve 342 is closed and the fifth valve 345 is opened, In response to the ink ejection operation by the recording head 22, the recording head 22 sends the ink to the flow path portion 222 via the inlet 223. The common ink channel 304 a has a diameter larger than that of the ink channels 301, 302 a, 302 b, 303, 305 a, 305 b, and 306 in order to suppress a pressure change in the tube due to fluctuations in the amount of ink flowing out to the recording head 22. The member which has is used.

The recording head 22 is provided at a position where the position of the nozzle 221n is higher than the ink level of the intermediate tank 33, the first valve 341 is closed, and the fourth valve 344 and the fifth valve 345 are opened. In this state, the ink in the recording head 22 is set to a negative pressure due to the water 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 discharge ink is suppressed.
Further, each recording head 22 has a portion of the recording head 22 that has a temperature corresponding to the temperature of the ink in the flow path portion 222 (for example, the ink in the flow path portion 222 such as a nozzle plate provided with an opening of the nozzle 221n. The head temperature detecting unit 23 (head temperature detecting means) for detecting the temperature of the portion (hereinafter also referred to as the head temperature Th) is attached. The head temperature detection unit 23 includes a temperature detection element such as a thermistor, for example, and outputs a detection result of the head temperature Th to the control unit 40 based on a control signal supplied from the CPU 41.

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

The ink flow path 305a is provided with a second valve 342 (switching means) that switches between opening and closing the ink flow path 305a. The ink flow path 305b is provided with a sixth valve 346 for switching between opening and closing of the ink flow path 305b. The ink flow path 305 a and the ink flow path 305 b merge with the ink flow path 306. Further, 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 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 detection unit 24a is provided. The vicinity of the sub tank 31 in this case refers to a range in which the ink temperature is substantially the same as the ink temperature when flowing into the sub tank 31. Here, it can be assumed that the temperature is substantially the same, for example, that the temperature difference is within 1 ° C.
The first ink temperature detection unit 24 a includes a temperature detection element such as a thermistor, for example, and outputs data related to the first ink temperature T <b> 1 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 the ink circulation path passing through the ink flow paths 301, 302 a, 303, the common ink flow path portion 304 a, and the ink flow paths 305 a, 306 according to the liquid feeding operation by the liquid feeding pump 27.

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

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 the third state), the ink flow path 302a in the ink circulation path. Instead, the ink can be circulated through a path passing through the ink flow path 302b.

Further, when the first valve 341, the second valve 342, and the sixth valve 346 are closed and the third valve to the fifth valve are opened (hereinafter referred to as a fourth state), they are stored in the sub tank 31. Ink can be supplied to the recording head 22 via the intermediate tank 33 and the common ink flow path portion 304a, and the negative pressure of the ink in the recording head 22 due to the above-described water head difference can be generated. In the present embodiment, the discharge 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 ink jet recording apparatus 1 includes the head unit 20, the recording head driving unit 21, the recording head 22, the head temperature detecting unit 23, the first ink temperature detecting unit 24a, the second ink temperature detecting unit 24b, and the ink temperature adjusting unit. 25, liquid feed pump 27, supply pump 51, vacuum pump 52, control unit 40, solenoid valve drive unit 26, transport drive unit 53, head unit movement drive unit 54, operation display unit 55, input An output interface 56 and a bus 57 are provided. Among these, the control unit 40 includes a CPU 41 (Central Processing Unit) (ink temperature adjusting means, liquid feeding control means, determination means, recording control means, switching control means), RAM 42 (Random Access Memory), ROM 43 (Read Only Memory), and A storage unit 44 is included.

The CPU 41 reads 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 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 ink in the ink circulation path and supplies ink to the recording head 22.

The RAM 42 provides a working memory space to the CPU 41 and stores temporary data. The RAM 42 stores data indicating the setting of the liquid pump pressure. The RAM 42 may include a nonvolatile 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 nonvolatile 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 apparatus 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 in combination.

The electromagnetic valve drive unit 26 outputs the drive signals to the first valve 341 to the sixth valve 346 based on the control signal supplied from the CPU 41, so that the first valve 341 to the sixth valve 346 are independent of each other. 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, so that the head unit 20 is positioned at a position facing the transport belt 103 and a position facing the cleaning unit. Move in the X direction.

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

The input / output interface 56 mediates data transmission / reception between the external device 2 and the control unit 40. The input / output interface 56 is configured by, for example, one 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 adjustment operation performed in the inkjet recording apparatus 1 will be described.

In the ink jet recording apparatus 1, in order to eject ink of an appropriate amount and speed from the nozzle 221 n of the recording head 22, the ink supplied to the recording head 22 is appropriately ejected before the image recording operation. An ink temperature adjustment operation is performed to adjust the temperature within a predetermined temperature range. In the present embodiment, the predetermined temperature range is 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. Hereinafter, the lower limit value of the temperature range is referred to as a lower limit temperature Tmin, and the upper limit value is referred to as an upper limit temperature Tmax.

The ink jet recording apparatus 1 of the present embodiment is a large apparatus that records an image on a recording medium P having a width of about 2 m. Each head unit 20 has a capacity of 40 liters or more in the ink circulation path of the ink supply mechanism 30. Ink is stored and circulated. Most of the ink (90% or more) is stored in the sub tank 31. For this reason, when the temperature of the ink in the ink circulation path is out of the above 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 when cooled, it takes time to adjust the temperature of the ink in the entire ink circulation path because the ratio of the amount of heated or cooled ink to the amount of ink in the entire ink circulation path is small. 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 304a. Therefore, the ink is heated or cooled each time. It is necessary to adjust the temperature. However, even if the ink flowing through the common ink flow path 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 through the ink circulation path. Thus, the temperature of the circulating ink becomes a heat medium and the temperature of the constituent members of the ink circulation path and 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 through the ink circulation path and flows into the sub tank 31 falls within a predetermined temperature range including the target temperature Tc, the ink temperature adjustment operation is terminated, and the image is recorded on the recording medium P. Operation starts.

When the ink temperature adjustment operation is started, the first ink temperature T1 is detected by the first ink temperature detector 24a. 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. Also, the first valve 341 and the second valve 342 are opened, the third to sixth valves are closed, the ink supply mechanism 30 is set to 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 falls within the predetermined temperature range, or before the temperature of the ink in the sub tank 31 falls within the predetermined temperature range. May be. 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 passing through the ink flow paths 301, 302 a, 303, the common ink flow path part 304 a, and the ink flow paths 305 a, 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 remains until it flows into the sub tank 31 again. To drop. 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. Thus, by continuing the heating of the ink in the sub tank 31 and the liquid feeding of the ink in the ink circulation path, 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. Will rise.

Therefore, immediately after the start of ink feeding 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 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 not less than the lower limit temperature Tmin and not more than the upper limit temperature Tmax, the temperature of the ink sent from the sub tank 31 and making a round of 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. Further, 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 2 ° C., for example. However, by setting the reference difference ΔTa to a large value within a range where the ink can be properly discharged by the recording head 22, the ink temperature adjustment operation time can be shortened. .
In the present embodiment, liquid feeding in the ink circulation path is continued until the first ink temperature T1 is not less than the lower limit temperature Tmin and not more than the upper limit temperature Tmax and the difference ΔT is not more than the reference difference ΔTa.

When the first ink temperature T1 is not less than the lower limit temperature Tmin and not more than the upper limit temperature Tmax, and the difference ΔT is within the reference difference ΔTa, heating by the heating device 25a is ended. In addition, the first valve 341 is closed, the third valve 343 and the fourth valve 344 are opened, the ink supply mechanism 30 is in the third state, and the temperature-adjusted ink in the sub tank 31 passes through the ink flow path 302b. It passes through and is stored in the intermediate tank 33. Thereby, the temperature of the intermediate tank 33 and the ink flow path 302b is adjusted to a temperature 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 entire amount of the ink circulation path. It is small enough for the heat capacity. For this reason, the temperature drop of the entire ink circulation path due to the inflow of ink into the intermediate tank 33 and the ink flow path 302b is negligible 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 ink is stored in the intermediate tank 33, the second valve 342 is closed, the fifth valve is opened, and the ink supply mechanism 30 is set to the fourth state. Then, the head unit 20 is moved to a position facing the cleaning unit, and the above-described discharge operation is performed. In this discharge operation, the ink in the flow path portion 222 of the recording head 22 is ejected from the nozzle 221n to the ink receiving portion, and the ink in the common ink flow path portion 304a adjusted within the predetermined temperature range is discharged. It flows into the flow path part 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 where the heat of the ink is transmitted are adjusted to a temperature 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 of the entire ink circulation path due to the inflow of ink into the flow path portion 222 of the recording head 22 in the discharge operation is negligible, and can be ignored in this embodiment.

When the ink is discharged a predetermined number of times from each nozzle 221n of the recording head 22, the discharge operation is terminated. Then, the head unit 20 is moved to a position facing the conveyance belt 103, and the ink temperature adjustment operation is completed. The discharge operation may be terminated when a predetermined time has elapsed in the case where the discharge operation is performed by discharging ink from the nozzles 221n at a predetermined frequency. Further, when the head temperature Th detected by the head temperature detection unit 23 is a temperature range not lower than the lower limit temperature Tmin and not higher than the upper limit temperature Tmax, or a temperature within a predetermined temperature range separately defined within the temperature range. Alternatively, the discharge operation may be terminated.

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

Next, an 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 process.
In the ink temperature adjustment process, 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. Or when an input operation from a user instructing execution of the ink temperature adjustment operation is performed on the operation display unit 55.

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 or not 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 electromagnetic valve driving unit 26, and performs the first valve 341 and the first valve 341. The ink supply mechanism 30 is set to the first state by opening the second valve 342 and closing the third valve 343 to the sixth valve 346 (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).

CPU41 supplies a control signal to the liquid feeding pump 27, and starts the liquid feeding by the liquid feeding pump 27 (step S104). Thereby, the ink in the sub tank 31 circulates in the ink circulation path passing through the ink flow paths 301, 302 a, 303, the common ink flow path portion 304 a, and the ink flow paths 305 a, 306. Note that the process of step S104 may be executed before the process of step S103.

The CPU 41 supplies control signals 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 not less than the lower limit temperature Tmin and not more than the upper limit temperature Tmax, and the difference ΔT between the first ink temperature T1 and the second ink temperature T2 is not more than the reference difference ΔTa. It is determined whether or not it is satisfied (step S105). If 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 temperature condition is satisfied (“Yes” in step S105), the CPU 41 supplies a control signal to the ink temperature adjustment unit 25, and the ink in the sub tank 31 is heated by the heating device 25a. Heating is terminated (step S106).

The CPU 41 supplies a control signal to the electromagnetic valve driving unit 26, closes the first valve 341, opens the third valve 343 and the fourth valve 344, and sets the ink supply mechanism 30 to the third state. As a result, ink storage 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 and terminates the liquid feed by the liquid feed pump 27 (step S108).

The CPU 41 supplies a control signal to the electromagnetic valve driving unit 26, closes the second valves 342, opens all the fifth valves 345, and sets the ink supply mechanism 30 to the fourth state (step S109).

CPU41 supplies a control signal to the head unit movement drive part 54, and moves the head unit 20 to the position facing a cleaning part. Then, a control signal is supplied to the recording head drive unit 21 to cause each recording head 22 to perform a discharge operation (step S110). When the ink is ejected a predetermined number of times from each nozzle 221 n of the recording head 22, the CPU 41 ends the discharging operation and moves the head unit 20 to a position facing the conveyance belt 103.

When it is determined in 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 determines that the first ink temperature T1 is higher than the upper limit temperature Tmax. It is discriminate | determined (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 processing from step S112 to step S116. Here, the process of step S112, step S114, and step S115 is the same as the process of step S102, step S104, and step S105, respectively. In the process of step S113, the CPU 41 supplies a control signal to the ink temperature adjustment unit 25, and starts cooling the ink in the sub tank 31 by the cooling device 25b. Further, in the process of step S116, the CPU 41 supplies a control signal to the ink temperature adjustment 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 equal to or lower than the upper limit temperature Tmax (“No” in step S111), or when the process of step S110 is completed, 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 detector 23 to detect the head temperature Th, and outputs the detection result to the controller 40 (step S201). .

CPU41 sets the voltage correction value which concerns on each recording head 22 according to 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 correction value of the voltage amplitude 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 according to 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 recording head driving unit 21, and causes the recording head driving unit 21 to output the driving signal of the voltage correction value set in step S202 to the recording head 22. Ink is ejected from the nozzles 221n onto the recording medium P conveyed by the conveying unit 10 to record an image on the recording medium P.

The CPU 41 determines whether or not an unexecuted image recording command is stored in the storage unit 44 (step S204). If it is determined that an unexecuted image recording command is recorded (“Yes” in step S204), the CPU 41 shifts the processing to step S201.
If it is determined that an unexecuted image recording command has not been 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 including the nozzle 221n that discharges ink and the flow path portion 222 that communicates with the nozzle 221n, and the plurality of recording heads 22. A sub tank 31 that stores the supplied ink, an ink temperature adjusting unit 25 and a CPU 41 that adjust the temperature of the ink stored in the sub tank 31 to be within a predetermined temperature range, the 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 section 304a communicating with the flow path section 222 of the head 22, and the ink in the ink circulation path flow in a predetermined liquid feeding direction. And a liquid feed pump 27 for performing a liquid feed operation for circulating the ink in the sub tank 31 in the ink circulation path. It is to perform the feeding operation to the feeding pump 27 so that the temperature of the ink in the ink circulation path approaches the target temperature Tc in the range of the predetermined temperature range (feed control unit). According to such a configuration, the ink heated or cooled in the sub tank 31 circulates in the ink circulation path as a heat medium, and heat moves between the ink and the constituent members of the ink circulation path. The temperature of the entire ink circulation path is adjusted. For this reason, the temperature of the ink supplied to the plurality of recording heads 22 can be further stabilized as compared with the configuration in which the ink flowing through 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.

The ink jet recording apparatus 1 further includes a first ink temperature detection unit 24a that detects the temperature of the ink in the ink circulation path immediately before flowing 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 the above is within a predetermined temperature range (determining means), and it is determined that the first ink temperature T1 is outside the predetermined temperature range. In this case, a liquid feeding operation is performed by the liquid feeding pump 27 (liquid feeding control means). Since the ink immediately before flowing into the sub tank 31 is the ink after heat has been exchanged with the constituent members of the ink circulation path, the ink circulation path has the first ink temperature T1 related to the ink. 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 the temperature of the ink in the ink circulation path is determined when the determination is made. It can adjust so that it may approach target temperature Tc.

The ink jet recording apparatus 1 further includes a second ink temperature detection unit 24b that detects the temperature of ink immediately after flowing 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 or not the difference ΔT between the first ink temperature T1 and the second ink temperature T2 detected by the second ink temperature detector 24b is within a predetermined reference difference ΔTa (discriminating means). When it is determined that the difference ΔT is larger than the reference difference ΔTa, the liquid feeding operation is performed by the liquid feeding pump 27 (liquid feeding control means). In the ink jet recording apparatus 1, the temperature distribution of the ink circulating in the ink circulation path becomes smaller as the temperature distribution in the ink circulation path becomes more uniform, and the first ink temperature T1 becomes a value closer to the second ink temperature T2. Thus, 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 then on the recording medium P. To perform a recording operation for recording an image (recording control means). Thereby, the ink whose temperature and viscosity are adjusted can be supplied to the recording head 22 so that the recording head 22 can appropriately discharge the ink. As a result, an image can be recorded with an appropriate image quality.

Further, the CPU 41 determines that the first ink temperature T1 is within the predetermined temperature range, and determines that the difference ΔT is within the reference difference ΔTa, the recording operation is performed by the plurality of recording heads 22. (Recording control means). According to such a configuration, the recording operation by the recording head 22 can be started in a state where the difference ΔT is within the reference difference ΔTa and the ink temperature is stable. Thereby, it is possible to cause the recording head 22 to stably and appropriately discharge ink.

Further, the inkjet recording apparatus 1 includes a plurality of head temperature detection units 23 that respectively detect the temperatures of portions of the plurality of recording heads 22 that correspond to the temperature of the ink in the flow path unit 222, and the CPU 41 includes 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 means). . According to such a configuration, even when the ink temperature fluctuates in accordance with the operation of the recording element 221 in the recording head 22, it is possible to perform proper ink ejection. As a result, it is possible to suppress deterioration in the image quality of the recorded image. Further, since the temperature of the ink supplied to the recording head 22 is adjusted in advance within a predetermined temperature range, the correction range of the voltage amplitude of the drive signal and the voltage application time can be reduced.

In addition, 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 path portion to be communicated and the common ink flow path portion 304a provided between the common ink flow path portion 304a and the sub tank 31 in the liquid feeding direction without passing through the flow path portions 222 of the plurality of recording heads 22. The inkjet recording apparatus 1 is provided in the range from the common ink channel 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 portion of the ink. The fifth valve 345 is closed the first branch passage portion when the circulation of the click is performed (switching control means). According to such a configuration, it is possible to suppress the occurrence of a problem that ink leaks from the nozzle 221n when ink is circulating in the ink circulation path.

The ink jet recording apparatus 1 includes a deaeration module 32 that is provided in the ink circulation path and desorbs the gas in the ink from the ink. Thereby, deaeration of the ink circulating in the ink circulation path can be performed in parallel with the temperature adjustment of the ink.

Further, the member constituting the ink circulation path is metal. According to such a configuration, the temperature of the members constituting 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 modification of the above embodiment will be described. The present modification is different from the above embodiment in that the liquid feeding amount per predetermined time by the liquid feeding pump 27 is changed during the execution of the ink temperature adjusting operation. Hereinafter, differences from the above embodiment will be described.

In this 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 T1 is detected by the first ink temperature detection unit 24a every predetermined time. . Then, the liquid feeding amount per predetermined time by the liquid feeding pump 27 is changed according to the difference between the detected first ink temperature T1 and the target temperature Tc. That is, the amount of liquid fed by the liquid feed pump 27 per predetermined time is changed so as to gradually increase 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 equal to or less than a predetermined value, the liquid supply pressure by the liquid supply pump 27 is constant regardless of the magnitude of the difference. You may make it become.

As described above, in the inkjet recording apparatus 1 according to the present modification, the CPU 41 increases the difference between the first ink temperature T1 detected by the first ink temperature detection unit 24a and the target temperature Tc per predetermined time. The liquid feeding operation is performed by the liquid feeding pump 27 so that the amount of ink fed gradually increases (liquid feeding control means). According to such a configuration, as the difference between the first ink temperature T1 and the predetermined target temperature Tc increases, the amount of ink that passes through each part of the ink circulation path per unit time increases, and the ink circulation path The amount of heat transferred 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.

Note that the present invention is not limited to the above-described embodiments and modifications, and various modifications can be made.
For example, in the above-described embodiment and modification, the ink temperature adjustment unit 25 has been described using an example including the heating device 25a and the cooling device 25b. The ink temperature adjustment unit 25 may include only the heating device 25a. For example, when the upper limit temperature Tmax is lower than the environmental temperature of the inkjet recording apparatus 1, the ink temperature adjustment unit 25 may include only the cooling device 25b.

In the embodiment and the modification, both the determination as to whether or not the first ink temperature T1 is within the 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 vary greatly in the ink temperature adjustment operation, the determination of whether or not the difference ΔT is equal to or less than the reference difference ΔTa 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 environmental temperature of the inkjet recording apparatus 1 and the operation settings of the ink temperature adjustment unit 25 and the liquid feed pump 27 that are set in advance in association with the elapsed time since the ink temperature adjustment operation was performed last. Thus, the ink temperature adjustment operation can be performed. In this case, the first ink temperature detection unit 24a may not be provided.

In the embodiment and the modification, the ink flow paths 301, 302a, 302b, 303, 305a, 305b, 306, the common ink flow path section 304a, the common waste liquid flow path section 304b, the sub tank 31 and the intermediate tank 33 are made of metal. Although described using an example of configuration, some or all of these may be configured of a material other than a 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 smaller specific heat and a higher thermal conductivity so that the temperature of the ink circulation path can be adjusted in a shorter time.

In the above-described embodiment and modification, the ink in the sub tank 31 has been described using an example of heating or cooling by the ink temperature adjusting unit 25. However, in addition to the ink temperature adjusting unit 25, 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, and a part of or all of the intermediate tank 33 are provided with a heating device for heating the ink passing therethrough and / or a cooling device for cooling it. It may be provided.

In the above-described embodiment and the modification, the configuration in which the temperature of the ink immediately after flowing out of the sub tank 31 (second ink temperature T2) is detected by the second ink temperature detection unit 24b is described as an example. Instead, 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.
In the above-described embodiment and the modification, the first ink temperature detection unit 24a has described the configuration of detecting the temperature of the ink immediately before flowing into the sub tank 31 (first ink temperature T1) as an example. Instead, the first ink temperature detection unit 24a is provided in the vicinity of the portion where the ink flows from the ink flow path 306 in the sub tank 31, and flows from the ink flow path 306 as the first ink temperature T1. The temperature of the ink before mixing with the ink in the sub tank 31 may be detected.

In the above-described embodiment and the modification, the description has been made using the example in which the ink whose temperature is adjusted is caused to flow into the flow path portion 222 of the recording head 22 by the discharge operation, 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 in the second state to circulate ink in the ink circulation path passing through the flow path portion 222 of the recording head 22, thereby causing the flow path portion. The temperature of 222 may be adjusted.

In the above-described embodiment and modification, the ink circulation path having the first and second branch flow paths has been described as an example. However, the ink circulation path has no branch flow path, for example, and the ink circulation path is the recording head. It may be configured to pass through the flow path portion.

In the above embodiment and the modification, an example is used in which the temperature of the ink is adjusted so that the plus side and the minus side of the target temperature Tc (25 ° C.) are within the range of 5 ° C. (20 ° C. to 30 ° C.). However, the plus temperature range with respect to the target temperature Tc may be smaller than the minus temperature range. For example, the temperature range on the minus side with respect to the target temperature Tc may be 5 ° C., the temperature range on the plus side may be 1 ° C., and the ink temperature may be adjusted to be within the range of 20 ° C. to 26 ° C. In this way, even if the temperature of the ink in the recording head 22 rises according to the operation frequency of the recording element 221, the temperature of the ink can be prevented from greatly deviating from the target temperature Tc.

In the above embodiment and the modification, the example using ink that is liquid at room temperature 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 discharges ink that is gel-like at room temperature and becomes sol when heated.

In the above embodiment and the modification, the single-pass inkjet recording apparatus 1 has been described as an example. However, the present invention may be applied to an inkjet recording apparatus that records an image while scanning a head unit. .

In the above-described embodiment and the modification, the example in which the recording medium P is transported by the transport unit 10 including the transport belt 103 has been described. However, the present invention is not limited to this example. The recording medium P may be held and conveyed on the outer peripheral surface of the drum.

Although several 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 equivalents thereof. .

The present invention can be used for an ink jet recording apparatus.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 External apparatus 10 Conveyance part 101,102 Conveyance roller 103 Conveyor belt 20 Head unit 21 Recording head drive part 22 Recording head 221 Recording element 221n Nozzle 222 Channel part 223 Inlet 224 Outlet 23 Head temperature detection 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 Solenoid valve drive unit 27 Liquid feed pump 30 Ink supply mechanisms 301, 302a, 302b, 303, 305a, 305b, 306 Ink flow path 304a Common ink flow path section 304b Common waste liquid flow path section 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 unit 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)

1. A plurality of recording heads each having a nozzle for ejecting ink and an ink flow path portion communicating with the nozzle;
   An ink reservoir for storing ink to be supplied to the plurality of recording heads;
   An ink temperature adjusting means for adjusting the temperature of the ink stored in the ink storage section to be within a predetermined temperature range;
   An ink circulation path through which the ink stored in the ink storage section circulates through the ink storage section and a common ink flow path section communicating with the ink flow path sections of the plurality of recording heads;
   Liquid feeding means for performing a liquid feeding operation for causing the ink in the ink circulation path to flow in a predetermined liquid feeding direction and circulating the ink in the ink reservoir in the ink circulation path;
   Liquid feeding control means for causing the liquid feeding means to perform the liquid feeding operation so that the temperature of the ink in the ink circulation path approaches a predetermined target temperature within the range of the predetermined temperature range;
   An ink jet recording apparatus comprising:
2. First ink temperature detection means for detecting the temperature of ink immediately before flowing into the ink storage portion of the ink in the ink circulation path;
   Discrimination means for discriminating whether or not the temperature detected by the first ink temperature detection means is within the predetermined temperature range;
   With
   The liquid feeding control unit causes the liquid feeding unit to perform the liquid feeding operation when the discrimination unit determines that the temperature is out of the predetermined temperature range. 2. An ink jet recording apparatus according to 1.
3. A second ink temperature detecting means for detecting the temperature of the ink in the ink reservoir or the temperature of the ink immediately after flowing out of the ink reservoir in the ink circulation path;
   The determining means determines whether or not a 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 inkjet recording according to claim 2, wherein the liquid feeding control unit causes the liquid feeding unit to perform the liquid feeding operation when the discrimination unit determines that the difference is larger than the reference difference. apparatus.
4. Recording in which an image is recorded on the recording medium by ejecting ink to the recording medium by the plurality of recording heads when the temperature is determined to be within the predetermined temperature range by the determining means. The inkjet recording apparatus according to claim 2, further comprising a recording control unit that performs an operation.
5. A second ink temperature detecting means for detecting the temperature of the ink in the ink reservoir or the temperature of the ink immediately after flowing out of the ink reservoir in the ink circulation path;
   The determining means determines whether or not a 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 plurality of recording heads when the recording control unit determines that the temperature is within the predetermined temperature range and the difference is within the reference difference by the determination unit. The inkjet recording apparatus according to claim 4, wherein the recording operation is performed.
6. A plurality of head temperature detection means for detecting the temperature of each of the plurality of recording heads, each of which is a temperature corresponding to the temperature of the ink in the ink flow path section;
   The recording control means 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 the temperature detected by each of the plurality of head temperature detecting means. An ink jet recording apparatus according to claim 4 or 5, wherein
7. The liquid feeding control means is configured to cause the liquid feeding amount to gradually increase as the difference between the temperature detected by the first ink temperature detecting means and the predetermined target temperature increases. 7. The ink jet recording apparatus according to claim 2, wherein the liquid feeding operation is performed by means.
8. The ink circulation path is provided between the common ink flow path section and the ink storage section in the liquid feeding direction, passes through the ink flow path sections of the plurality of recording heads, and the common ink flow path section. A first branch channel that communicates with the ink reservoir, and the ink channels of the plurality of recording heads provided between the common ink channel and the ink reservoir in the liquid feeding direction. A second branch flow path portion that allows the common ink flow path portion and the ink storage portion to communicate with each other without passing through;
   The ink jet recording apparatus
   Switching means provided in a range from the common ink flow path portion to the plurality of recording heads in the liquid feeding direction to open or close the first branch flow path portion;
   Switching control means for closing the first branch flow path portion by the switching means when ink circulation is performed in the ink circulation path by the liquid feeding operation;
   The inkjet recording apparatus according to any one of claims 1 to 7, further comprising:
9. The ink jet recording apparatus according to any one of claims 1 to 8, further comprising a deaeration unit that is provided in the ink circulation path and desorbs a gas in the ink from the ink.
10. 10. The ink jet recording apparatus according to claim 1, wherein the member constituting the ink circulation path is a metal.

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