JP2011016273A - Image recording apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image recording apparatus which shortens time from starting up to printing.SOLUTION: The image recording apparatus 1 includes four ink circulating mechanisms 2-5 each with a pump 13 for circulating an ink, a temperature detecting part for detecting a temperature T of the ink I and outputting as information, and an inkjet head 17 for forming an image by ejecting the circulated ink I onto a recording medium; a heat exchanger 6 which is arranged to be astride the midway of the ink circulating mechanisms 2-5 of four colors to exchange heat among the inks I; and a control part 7 to which the information of the temperature T of the ink I is input from the temperature detecting part 26 and which controls a circulation velocity of the ink by the pump 13. The control part 7 controls the circulation velocity of each unused ink I by the pump 13 on the basis of the comparison result between an average temperature TA of the use ink I of N colors with the temperature T of the unused ink when N is an integer satisfying 1≤N≤3, and N colors are printed as the use ink I.

Description

  The present invention relates to an image recording apparatus including a plurality of ink circulation mechanisms that circulate ink.

  There is known an image recording apparatus that includes a plurality of ink circulation mechanisms that circulate ink and records an image on printing paper or the like with ink in a predetermined printing temperature region.

  Patent Document 1 discloses an image recording apparatus including four ink circulation mechanisms for circulating four color inks and a heat exchanger for exchanging heat between the inks. Each ink circulation mechanism includes an ink tank, an upper tank, a lower tank, and an inkjet head. The heat exchanger is provided in the middle of each circulation system. The heat exchanger is provided with temperature adjusting means.

  In the image recording apparatus of Patent Document 1, when ink is circulated by each ink circulation mechanism, the inks exchange heat with each other via the heat exchanger. Thereby, the temperature of each ink is averaged. In this state, when the temperature of the ink is in a printing temperature region where printing can be performed by a heater or the like, the ink is ejected from the inkjet head. As a result, an image is recorded on the printing paper.

JP 2008-224176 A

  However, in the image recording apparatus of Patent Document 1, even when there is unused ink in single color printing or the like, heat exchange is performed through the heat exchanger in the same manner as in full color printing. For this reason, the ink used is unnecessarily deprived of heat by the unused ink, or conversely, unnecessary heat is transmitted from the unused ink. As a result, there is a problem that it takes a long time for the ink temperature to reach the printing temperature region, and the startup time until printing becomes long.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide an image recording apparatus that can shorten the startup time until printing.

In order to achieve the above object, the invention described in claim 1 is a circulation means for circulating ink, a temperature detection unit for detecting the temperature of the ink and outputting it as information, and the circulating ink on a recording medium. An ink jet head that forms an image by ejecting the ink to each of the Q ink circulation mechanisms, and the heat exchange for exchanging heat between the inks provided across the middle part of the Q ink circulation mechanisms And a controller for controlling the circulation speed of the ink by the circulation means, as well as information on the temperature of the ink from the temperature detector.
The controller is
N is 1 ≦ N ≦ Q−1 and an integer,
When printing N pieces as used ink, if at least one of the temperatures of the N used inks is not in the printing temperature range, the average temperature TA of the N used inks is compared with the temperature of the unused ink. Based on the result, the circulation speed of each unused ink is controlled by the circulation means.

  Further, in the invention according to claim 2, when the average temperature TA of the N used inks is lower than the printing temperature range, the control unit has a temperature higher than the average temperature TA of the N used inks. It is characterized in that high unused ink is circulated at a speed higher than the circulation speed of the used ink.

  According to a third aspect of the present invention, when the average temperature TA of the N used inks is lower than the printing temperature range, the control unit has a temperature higher than the average temperature TA of the N used inks. The low unused ink is circulated at a speed lower than the circulation speed of the used ink.

  According to a fourth aspect of the present invention, when the average temperature TA of the N used inks is higher than the printing temperature range, the control unit has a temperature higher than the average temperature TA of the N used inks. High unused ink is circulated below the circulation speed of the used ink.

  Further, in the invention according to claim 5, when the average temperature TA of the N used inks is higher than the printing temperature range, the control unit has a temperature higher than the average temperature TA of the N used inks. The low unused ink is circulated at a speed higher than the circulation speed of the used ink.

  According to a sixth aspect of the present invention, each of the ink circulation mechanisms includes a heating unit or a cooling unit, and the control unit controls the heating unit or the cooling unit for each of the ink circulation mechanisms. To do.

  According to the first aspect of the present invention, the control unit controls the circulation speed of the unused ink based on the comparison result between the average temperature of the used ink and the temperature of the unused ink. As a result, the present invention can suppress the unnecessary conduction of heat from the used ink to the unused ink and the unnecessary conduction of heat from the unused ink to the used ink. As a result, according to the present invention, the time required for the used ink to reach the printing temperature region can be shortened, and the startup time until printing can be shortened.

  According to the invention of claim 2, when the average temperature TA of the used ink is lower than the printing temperature range, the control unit circulates unused ink having a temperature higher than the average temperature TA at a speed equal to or higher than the circulation speed of the used ink. Let Thereby, more heat is transferred from the unused ink through the heat exchanger to the used ink that needs to be heated below the printing temperature range. For this reason, the used ink can be efficiently heated. As a result, according to the second aspect of the invention, the time until the used ink reaches the printing temperature region can be shortened, so that the startup time until printing can be shortened.

  According to the invention of claim 3, when the average temperature TA of the used ink is lower than the printing temperature range, the control unit circulates unused ink having a temperature lower than the average temperature TA at a speed lower than the circulation speed of the used ink. Let Thereby, it can suppress that heat transfers to the unused ink from the used ink which needs to be heated lower than a printing temperature range via a heat exchanger. For this reason, the used ink can be efficiently heated. As a result, the invention according to claim 3 can reduce the time until the used ink reaches the printing temperature region, so that the start-up time until printing can be shortened.

  According to the invention of claim 4, when the average temperature TA of the used ink is higher than the printing temperature region, the control unit circulates the unused ink having a temperature higher than the average temperature TA at a speed lower than the circulation speed of the used ink. Let Thereby, it can suppress that a heat | fever transfers to the use ink which needs to cool higher than a printing temperature range from an unused ink via a heat exchanger. For this reason, the used ink can be efficiently cooled. As a result, the invention according to claim 4 can reduce the time until the used ink reaches the printing temperature region, so that the start-up time until printing can be shortened.

  According to the invention of claim 5, when the average temperature TA of the used ink is higher than the printing temperature region, the control unit circulates unused ink having a temperature lower than the average temperature TA at a speed equal to or higher than the circulation speed of the used ink. Let As a result, more heat is transferred from the used ink that needs to be cooled above the printing temperature range to the unused ink through the heat exchanger. For this reason, the used ink can be efficiently cooled. As a result, the invention according to claim 5 can shorten the time until the used ink reaches the printing temperature region, and therefore the start-up time until printing can be shortened.

  According to the invention of claim 6, the heating means and the cooling means of each ink circulation mechanism are individually controlled. Accordingly, the invention of claim 6 can efficiently maintain the used ink in the printing temperature region.

1 is a schematic configuration diagram of an image recording apparatus according to a first embodiment. It is a block diagram explaining the control system of an image recording device. It is a flowchart explaining the image recording process by the image recording device of 1st Embodiment. It is a flowchart explaining a monochrome printing pre-process. It is a flowchart explaining a 1st temperature process. It is a flowchart explaining a 1st circulation process. It is a flowchart explaining a 2nd temperature process. It is a flowchart explaining a 2nd circulation process. It is a flowchart explaining a 3rd temperature process. It is a flowchart explaining a 3rd circulation process. It is a flowchart explaining a special color printing pre-process. It is a block diagram explaining the control system of the image recording apparatus of 2nd Embodiment.

(First embodiment)
Hereinafter, a first embodiment in which the present invention is applied to an image recording apparatus using an ink jet method capable of four-color printing will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image recording apparatus according to the first embodiment. FIG. 2 is a block diagram illustrating a control system of the image recording apparatus.

  As shown in FIGS. 1 and 2, the image recording apparatus 1 according to the first embodiment includes single color printing (printing with one color ink), special color printing (printing with two or three color inks), and full color printing (printing with one color ink). The image is recorded on a printing paper or the like by any one of four color ink printing.

  The image recording apparatus 1 includes an ink circulation mechanism 2 through which black ink IK is circulated, an ink circulation mechanism 3 through which cyan ink IC is circulated, an ink circulation mechanism 4 through which magenta ink IM is circulated, An ink circulation mechanism 5 through which the ink IY is circulated, a heat exchanger 6, and a control unit 7 are provided. In the following description, black is “K”, cyan is “C”, magenta is “M”, and yellow is “Y”. Then, any of “K”, “C”, “M”, and “Y” is added to the configuration regarding each color at the end of the code. In the case where it is not particularly necessary to limit the description to colors, “K to Y” will be omitted.

  As shown in FIG. 1, the black ink circulation mechanism 2 includes an ink bottle 11K, a lower tank 12K, a pump (corresponding to the circulation means in claims) 13K, a heater 14K, a cooler 15K, and an upper tank. 16K, the inkjet head 17K, and the piping 18K which connects between each structure are provided.

  The ink bottle 11K stores the supply ink IK. The ink bottle 11K is connected to the lower tank 12K via a pipe 18K. The ink IK that circulates through the ink circulation mechanism 2 is supplied from the ink bottle 11K to the lower tank 12K so as to have a constant circulation amount.

  The lower tank 12K temporarily stores the ink IK supplied from the ink bottle 11K. The lower tank 12K is connected to the upper tank 16K via a pipe 18K.

  The pump 13K circulates the ink IK. The pump 13K is provided in the middle of a pipe 18K that connects the lower tank 12K and the upper tank 16K. The pump 13K pumps the ink IK stored in the lower tank 12K installed below to the upper tank 16K installed above.

  The heater 14K heats the circulating ink IK. The heater 14K is provided in the middle of a pipe 18K that connects the lower tank 12K and the upper tank 16K.

  The cooler 15K cools the circulating ink IK. The cooler 15K is provided in the middle of a pipe 18K that connects the lower tank 12K and the upper tank 16K. The cooler 15K includes a fan 21K and a heat sink 22K provided at a position facing the fan 21K.

  The upper tank 16K temporarily stores the ink IK supplied from the lower tank 12K. The upper tank 16K is connected to the inkjet head 17K via a pipe 18K. The upper tank 16K appropriately supplies ink IK to the inkjet head 17K.

  The ink-jet head 17K forms an image by ejecting the circulating ink IK as droplets on a recording medium such as paper. The ink jet head 17K includes a main body portion 25K, a temperature detection portion 26K, and a driver 27K.

  The main body 25K includes a piezoelectric member for applying pressure to the ink IK and an electrode for applying a voltage to the piezoelectric member.

  The temperature detector 26K detects the temperature TK of the ink IK supplied into the main body 25K. The temperature detection unit 26K outputs the detected temperature TK of the ink IK to the control unit 7 as information.

  The driver 27K is for applying a voltage to the electrode of the main body 25K.

  The other ink circulation mechanisms 3 to 5 have substantially the same configuration except that the ink circulation mechanism 2 and the flowing ink are different. Therefore, description of the other ink circulation mechanisms 3 to 5 is omitted.

  The heat exchanger 6 exchanges heat by conducting heat between the ink I and the ink I circulating through the ink circulation mechanisms 2 to 5. Thereby, the temperatures TK, TC, TM, and TY of the inks IK, IC, IM, and IY are averaged. The heat exchanger 6 is disposed between the heater 14 and the cooler 15 and the lower tank 12. The heat exchanger 6 is provided so as to straddle the pipes 18K, 18C, 18M, and 18Y of the ink circulation mechanisms 2 to 5. The heat exchanger 6 is made of a material having high thermal conductivity such as aluminum or copper. The heat exchanger 6 is formed with through holes (not shown) through which the four pipes 18K, 18C, 18M, and 18Y pass.

  The control unit 7 is responsible for overall control of the image recording apparatus 1. As shown in FIG. 2, the control unit 7 includes a CPU 31 that executes each process, a RAM 32 that temporarily stores information such as temperature, a ROM 33 that stores programs and the like, and each of the components 31 to 33. And an I / O port 34 to be connected.

  The pump 13, the heater 14, the fan 21, the temperature detector 26, and the driver 27 of each ink circulation mechanism 2 to 5 are connected to the I / O port 34 of the controller 7. An input unit 90 such as a personal computer or a storage medium for inputting image data to the control unit 7 is connected to the I / O port 34 of the control unit 7.

  The control unit 7 individually controls the heater 14 and the fan 21 for each of the ink circulation mechanisms 2 to 5 based on the information on the temperature T of the used ink I input from the temperature detection unit 26 of the inkjet head 17. .

  Specifically, the case where the temperature T of the used ink I is lower than the printing temperature region TP (that is, T <TP) or the temperature region TPL is lower than the printing temperature region TP is applicable. The heater 14 for the ink I used is turned on and the fan 21 is turned off.

  Further, when the temperature T of the used ink I is higher than the printing temperature region TP (that is, T> TP) or when the temperature TTP is higher than the printing temperature region TP, the corresponding used ink I is used. The fan 21 is turned on and the heater 14 is turned off.

  The control unit 7 sets the heater 14 and the fan 21 for the unused ink I to OFF.

Here, the printing temperature region TP is a temperature at which the ink I ejected as droplets can have an appropriate viscosity. The upper limit temperature TH of the printing temperature region TP is 45 ° C., and the lower limit temperature TL of the printing temperature region TP is 25 ° C. The temperature constant α is set to 0.3. And, the lower temperature region TPL of the printing temperature region TP is
TL ≦ TPL <TL + α (TH−TL)
２５ 25 ℃ ≦ TPL <31 ℃
And In addition, a higher temperature region TPH of the printing temperature region TP,
TH-α (TH-TL) <TPH ≦ TH
３９ 39 ℃ <TPH ≦ 45 ℃
And Furthermore, the optimum temperature region TPM of the printing temperature region TP that is neither the lower temperature region TPL nor the higher temperature region TPH,
TL + α (TH−TL) ≦ TPM ≦ TH−α (TH−TL)
⇔ 31 ℃ ≦ TPM ≦ 39 ℃
And In other words, “TPL <TPM <TPH”.

The controller 7 controls the circulation speed of the ink I by the pump 13. Specifically, the control unit 7 controls the circulation speed of the used ink I to be “V0” via the pump 13. Further, the control unit 7 compares the average temperature TA of the used ink I with the temperature T of each unused ink I. Then, the control unit 7 controls the circulation speed of the corresponding unused ink I to V _HIGH or V _LOW via the pump 13 of the unused ink I based on the comparison result. here,
0 ≦ V _LOW <V0 ≦ V _HIGH
It is. As described above, V _LOW includes “0”. That is, the circulation at the circulation speed V _LOW is a concept including circulation stop.

Furthermore,
N: Number of inks used (1 ≦ N ≦ 3 and integer)
Temperature of each ink used: Ta1, Ta2, ... TaN
Then, the average temperature TA of the ink I used is
TA = (Ta1 + .. + TaN) / N
It becomes. In addition, when the used ink I is one color, that is, in the case of monochrome printing, the temperature T of the used ink I becomes the average temperature TA of the used ink I.

  Hereinafter, the circulation speed of the unused ink I controlled by the control unit 7 will be described more specifically based on the comparison result between the average temperature TA of the used ink I and the temperature T of the unused ink I.

When the average temperature TA of the N used inks I is lower than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is higher than the average temperature TA of the N used inks I. Circulation is performed at a circulation speed V0 or higher, that is, at a circulation speed V _HIGH .

When the average temperature TA of the N used inks I is lower than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA of the N used inks I. Circulation is performed at a circulation speed less than V0, that is, at a circulation speed _VLOW .

When the average temperature TA of the N used inks is higher than the printing temperature region TP, the control unit 7 circulates the unused ink I whose temperature is higher than the average temperature TA of the N used inks I. Circulation is performed at a speed less than V0, that is, at a circulation speed _VLOW .

When the average temperature TA of the N used inks is higher than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA of the N used inks I as the circulation speed of the used ink. Circulation is performed at V0 or higher, that is, at a circulation speed V _HIGH .

When the average temperature TA of the N used inks I is a lower temperature region TPL of the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is higher than the average temperature TA of the N used inks I. The ink I is circulated at a circulation speed V0 or higher, that is, at a circulation speed V _HIGH .

When the average temperature TA of the N used inks I is a lower temperature region TPL of the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA of the N used inks I. The ink I is circulated at a circulation speed less than V0, that is, at a circulation speed _VLOW .

When the average temperature TA of the N used inks is the higher temperature range TPH of the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is higher than the average temperature TA of the N used inks I. The ink I is circulated at a circulation speed less than V0, that is, at a circulation speed _VLOW .

When the average temperature TA of the N used inks is the higher temperature range TPH of the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA of the N used inks I. The ink is circulated at a circulation speed V0 or higher, that is, at a circulation speed V _HIGH .

When the temperature of the N use inks I is the printing temperature region TP and the average temperature TA of the N use inks I is the appropriate temperature region TPM of the printing temperature region TP, the control unit 7 The unused ink I that is the appropriate temperature region TPM in the printing temperature region TP is circulated at a circulation speed V0 or higher of the used ink I, that is, at a circulation speed V _HIGH .

When the temperature of the N use inks I is the printing temperature region TP and the average temperature TA of the N use inks I is the appropriate temperature region TPM of the printing temperature region TP, the control unit 7 The unused ink I that is not in the proper temperature region TPM in the printing temperature region TP is circulated at a speed lower than the circulation speed V0 of the used ink I, that is, at the circulation speed V _LOW .

In summary, when increasing the heat conduction between the used ink I and the unused ink I, the control unit 7 sets the circulation speed of the unused ink I to “V _HIGH ”. On the other hand, when reducing the conduction of heat between the used ink I and the unused ink I, the control unit 7 sets the circulation speed of the unused ink I to “V _LOW ”.

  Further, the control unit 7 controls the voltage applied to the electrodes via the driver 27 of the inkjet head 17 based on the image data. As a result, the ink I is ejected as droplets from the main body portion 25 of the inkjet head 17, and an image is recorded on a printing paper or the like.

  Next, an image recording process performed by the image recording apparatus 1 according to the first embodiment will be described with reference to the drawings.

FIG. 3 is a flowchart for explaining image recording processing by the image recording apparatus of the first embodiment. FIG. 4 is a flowchart for explaining the monochromatic pre-printing process. FIG. 5 is a flowchart illustrating the first temperature process. FIG. 6 is a flowchart illustrating the first circulation process. FIG. 7 is a flowchart illustrating the second temperature process. FIG. 8 is a flowchart illustrating the second circulation process. FIG. 9 is a flowchart for explaining the third temperature process.
FIG. 10 is a flowchart illustrating the third circulation process. FIG. 11 is a flowchart for explaining the special color printing pre-process. In each flowchart, the number after “S” indicates a step number.

  In the following description, for the sake of convenience, in the monochrome printing, the black ink IK is used as the used ink (or the first used ink). The cyan ink IC is the first unused ink, the magenta ink IM is the second unused ink, and the yellow ink IY is the third unused ink. Further, the average temperature TA of the ink used in monochromatic printing is the temperature TK of the black ink IK because the ink used is only the black ink IK.

In the special color printing, two inks IK and IC will be described as inks used (that is, N = 2). The black ink IK is the first used ink, and the cyan ink IC is the second used ink. The magenta ink IM is the first unused ink, and the yellow ink IY is the second unused ink. The average temperature TA of the ink used in the special color printing is an average of the temperatures TK and TC of the inks IK and IC used. That is,
TA = (TK + TC) / 2
It becomes.

<All color printing>
First, as shown in FIG. 3, the control unit 7 determines whether or not all color printing is performed based on the image data input from the input unit 90 (S1). When the control unit 7 determines that all color printing is performed (S1: Yes), the control unit 7 executes the all color printing pre-processing (S2).

(All-color printing pre-processing)
All inks I are used inks in all color printing. Therefore, in the pre-printing process for all colors, the control unit 7 compares the temperature T of all the inks I input from the temperature detection unit 26 with the printing temperature region TP, and turns on / off the heater 14 and the fan 21. Control off. Thereby, the temperature T of the ink I is set to the printing temperature region TP. Further, the ink I and the other ink I exchange heat with each other by the heat exchanger 6 provided so as to straddle the four pipes 18K, 18C, 18M, and 18Y. As a result, the temperatures TK, TC, TM, and TY of the four color inks IK, IC, IM, and IY are averaged.

  Further, the control unit 7 turns on the pumps 13 of all the ink circulation mechanisms 2 to 5. As a result, all the ink I circulates through the lower tank 12, the upper tank 16 and the inkjet head 17 connected by the pipe 18. Here, in all color printing, since all the inks I are used, the control unit 7 controls the pump 13 so that the circulation speed of all the inks I becomes “V0”.

(All color printing process)
Next, the control unit 7 executes the all color printing process (S3). Specifically, the control unit 7 conveys the printing paper. Thereafter, the control unit 7 applies a voltage to the electrodes of the inkjet head 17 via the driver 27 based on the image data input from the input unit 90. As a result, the ink I receives pressure from the piezoelectric member of the inkjet head 17 and is ejected as droplets. As a result, four color images are printed on the printing paper.

  Next, the control unit 7 determines whether or not the printing is finished based on the image data and the number of printed sheets (S4). If the control unit 7 determines that the printing is not finished (S4: No), it repeats Steps S2 and S3. On the other hand, when the control unit 7 determines that the printing is finished (S4: Yes), the image recording process by the all color printing is finished.

<Single color printing>
On the other hand, when the control unit 7 determines in step S1 shown in FIG. 3 that the printing is not all-color printing based on the image data (S1: No), it determines whether or not the printing is monochrome printing (S5). Next, if the control part 7 determines with monochrome printing (S5: Yes), it will perform the monochrome printing pre-process shown in FIG. 4 (S6).

(Single color pre-processing)
In the monochromatic printing pre-process shown in FIG. 4, the control unit 7 first determines whether or not the temperature TK of the used ink IK is in the printing temperature region TP (S21).

  When the control unit 7 determines that the temperature TK of the used ink IK is in the printing temperature region TP (S21: Yes), the control unit 7 determines whether the temperature TK of the used ink IK is in the appropriate temperature region TPM of the printing temperature region TP (S22). ).

  Next, when the control unit 7 determines that the temperature TK of the used ink IK is the appropriate temperature region TPM of the printing temperature region TP (S22: Yes), the control unit 7 executes the first temperature process shown in FIG. 5 (S23).

(First temperature treatment)
In the first temperature process shown in FIG. 5, first, the control unit 7 sets “n = 0” (S101).

  Next, the control unit 7 increments n by “1” to “n = 1” (S102).

  Next, the control unit 7 turns off the heater 14K of the first used ink (= black ink) IK (S103).

  Next, the control unit 7 turns off the fan 21K of the first used ink IK (S104).

  Next, the control unit 7 determines whether or not “n = N” (S105). Here, in the case of monochrome printing, since “N = 1”, the control unit 7 ends the first temperature process.

  As shown in FIG. 4, when the first temperature process is completed, the controller 7 executes the first circulation process shown in FIG. 6 (S24).

(First circulation process)
In the first circulation process shown in FIG. 6, the control unit 7 first controls the pump 13K of the used ink IK to circulate the used ink IK at the circulation speed V0 (S110).

  Next, the control unit 7 sets “m = 0” (S111).

  Next, the control unit 7 increments m by “1” to “m = 1” (S112).

  Next, the control unit 7 determines whether or not the temperature TC of the first unused ink (= cyan ink) IC is the appropriate temperature region TPM of the printing temperature region TP (S113).

Next, in step S113, when the control unit 7 determines that the temperature TC of the first unused ink IC is the appropriate temperature region TPM of the printing temperature region TP (S113: Yes), the control unit 7 controls the pump 13C to perform the first operation. 1 The unused ink IC is circulated at the circulation speed V _HIGH (S114).

On the other hand, when the control unit 7 determines in step S113 that the temperature TC of the first unused ink IC is not the appropriate temperature region TPM of the printing temperature region TP (S113: No), the control unit 7 controls the pump 13C to control the first unused ink IC. The used ink IC is circulated at the circulation speed V _LOW (S115).

  Next, the control unit 7 determines whether m is “4-N” (S116). Here, in the case of monochrome printing, since “N = 1”, “4-N = 3”.

Next, since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to Step S112 (S116: No). Thereafter, the control unit 7 also executes the processes of steps S112 to S116 for the second unused ink (= magenta ink) IM and the third unused ink (= yellow ink) IY. Accordingly, the second unused ink IM and the third unused ink IY are also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, when the control unit 7 determines in step S116 that “m = 3” (S116: Yes), the first circulation process is terminated.

  On the other hand, in step S22 shown in FIG. 4, when the control unit 7 determines that the temperature TK of the used ink IK is not in the proper temperature region TPM (S22: No), the temperature TK of the used ink IK is higher than the printing temperature region TP. It is determined whether it is TPH (S26).

  Next, when the temperature TK of the used ink IK is determined to be high in the temperature region TPH in step S26 (S26: Yes), the control unit 7 executes the second temperature process shown in FIG. 7 (S27).

(Second temperature treatment)
In the second temperature process shown in FIG. 7, the controller 7 first sets “n = 0” (S121).

  Next, the control unit 7 increments n by “1” to “n = 1” (S122).

  Next, the control unit 7 turns off the heater 14K of the first used ink (= black ink) IK (S123).

  Next, the control unit 7 turns on the fan 21K of the first used ink IK (S124).

  Next, the control unit 7 determines whether or not “n = N” (S125). Here, in the case of monochrome printing, since “N = 1”, the control unit 7 ends the second temperature process.

  As shown in FIG. 4, when the second temperature process is completed, the control unit 7 executes a second circulation process shown in FIG. 8 (S28).

(Second circulation process)
In the second circulation process shown in FIG. 8, the controller 7 first controls the pump 13K for the used ink IK to circulate the used ink IK at the circulation speed V0 (S130).

  Next, the control unit 7 sets “m = 0” (S131).

  Next, the control unit 7 increments m by “1” to “m = 1” (S132).

  Next, the control unit 7 determines whether or not the temperature TC of the first unused ink (= cyan ink) IC is higher than the average temperature TA (= TK) of the used ink IK (S133).

Next, when the control unit 7 determines in step S133 that the temperature TC of the first unused ink IC is higher than the average temperature TA of the used ink IK (S133: Yes), the pump of the first unused ink IC. The first unused ink IC is circulated at the circulation speed V _LOW by controlling 13C (S134). As a result, the heat transmitted from the first unused ink IC having a high temperature to the used ink IK requiring cooling through the heat exchanger 6 is reduced.

On the other hand, if the control unit 7 determines in step S133 that the temperature TC of the first unused ink IC is not higher than the average temperature TA of the used ink IK (S133: No), the pump of the first unused ink IC is pumped. 13C is controlled to circulate the first unused ink IC at the circulation speed V _HIGH (S135). As a result, the heat transferred from the used ink IK requiring cooling to the first unused ink IC having a low temperature through the heat exchanger 6 increases.

Next, the control unit 7 determines whether m is “4-N” (S136). Here, in the case of monochrome printing, since “N = 1”, “4-N = 3”. Since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to step S132 (S136: No). Thereafter, the control unit 7 also executes the processes of steps S132 to S136 for the second unused ink (= magenta ink) IM and the third unused ink (= yellow ink) IY. Accordingly, the second unused ink IM and the third unused ink IY are also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, if the control part 7 determines with "m = 3" in step S136 (S136: Yes), it will complete | finish a 2nd circulation process.

  On the other hand, in step S26 shown in FIG. 4, the control unit 7 determines that the temperature TK of the used ink IK is not the elevated temperature region TPH of the printing temperature region TP (S26: No), that is, the temperature TK of the used ink IK is the printing temperature region. If it is determined that the temperature range TPL is lower than TP, the third temperature process shown in FIG. 9 is executed (S30).

(Third temperature treatment)
In the third temperature process shown in FIG. 9, the controller 7 first sets “n = 0” (S141).

  Next, the control unit 7 increments n by “1” to “n = 1” (S142).

  Next, the control unit 7 turns on the heater 14K of the first used ink (= black ink) IK (S143).

  Next, the control unit 7 turns off the fan 21K of the first used ink IK (S144).

  Next, the control unit 7 determines whether or not “n = N” (S145). Here, in the case of monochrome printing, since “N = 1”, the control unit 7 ends the third temperature process.

  As shown in FIG. 4, when the third temperature process is completed, the control unit 7 executes the third circulation process shown in FIG. 10 (S31).

(Third circulation processing)
In the third circulation process shown in FIG. 10, the controller 7 first controls the pump 13K of the used ink IK to circulate the used ink IK at the circulation speed V0 (S150).

  Next, the control unit 7 sets “m = 0” (S151).

  Next, the control unit 7 increments m by “1” to “m = 1” (S152).

  Next, the control unit 7 determines whether or not the temperature TC of the first unused ink (= cyan ink) IC is lower than the average temperature TA (= TK) of the used ink IK (S153).

Next, when the control unit 7 determines in step S153 that the temperature TC of the first unused ink IC is lower than the average temperature TA of the used ink IK (S153: Yes), the pump of the first unused ink IC. By controlling 13C, the first unused ink IC is circulated at the circulation speed V _LOW (S154). Thereby, the heat transmitted from the used ink IK requiring heating to the first unused ink IC having a low temperature through the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S153 that the temperature TC of the first unused ink IC is not lower than the average temperature TA of the used ink IK (S153: No), the pump of the first unused ink IC is pumped. By controlling 13C, the first unused ink IC is circulated at the circulation speed V _HIGH (S155). As a result, the heat transmitted from the first unused ink IC having a high temperature to the used ink IK requiring heating through the heat exchanger 6 increases.

Next, the control unit 7 determines whether m is “4-N” (S156). Here, in the case of monochrome printing, since “N = 1”, “4-N = 3”. Since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to Step S152 (S156: No). Thereafter, the control unit 7 also executes the processes of steps S152 to S156 for the second unused ink (= magenta ink) IM and the third unused ink (= yellow ink) IY. Accordingly, the second unused ink IM and the third unused ink IY are also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, when determining that “m = 3” (S156: Yes), the control unit 7 ends the third circulation process.

  On the other hand, when the control unit 7 determines in step S21 shown in FIG. 4 that the temperature TK of the used ink IK is not in the printing temperature region TP (S21: No), it determines whether printing is in progress (S41).

  Next, when the control unit 7 determines that printing is being performed (S41: Yes), printing is stopped (S42). Stopping printing includes stopping the conveyance of printing paper and stopping the application of voltage to the inkjet head 17K to which the used ink IK is supplied.

  Next, the control unit 7 determines whether or not the temperature TK of the used ink IK is higher than the printing temperature region TP (S43).

  Next, when the control unit 7 determines that the temperature TK of the used ink IK is higher than the printing temperature region TP (S43: Yes), the second temperature process (S44) is performed. The second temperature process in step S44 is the same as the second temperature process shown in step S27 and FIG.

  Next, the control part 7 performs a 2nd circulation process (S45). The second circulation process in step S45 is the same as the second circulation process shown in step S28 and FIG.

(Second circulation process)
In the second circulation process illustrated in FIG. 8, first, the control unit 7 executes the processes of steps S <b> 130 to S <b> 132.

  Next, the control unit 7 determines whether or not the temperature TC of the first unused ink (= cyan ink) IC is higher than the average temperature TA (= TK) of the used ink IK (S133).

Next, when the control unit 7 determines in step S133 that the temperature TC of the first unused ink IC is higher than the average temperature TA of the used ink IK (S133: Yes), the pump of the first unused ink IC. The first unused ink IC is circulated at the circulation speed V _LOW by controlling 13C (S134). As a result, the heat transmitted from the first unused ink IC having a high temperature to the used ink IK requiring cooling through the heat exchanger 6 is reduced.

On the other hand, if the control unit 7 determines in step S133 that the temperature TC of the first unused ink IC is not higher than the average temperature TA of the used ink IK (S133: No), the pump of the first unused ink IC is pumped. 13C is controlled to circulate the first unused ink IC at the circulation speed V _HIGH (S135). As a result, the heat transferred from the used ink IK requiring cooling to the first unused ink IC having a low temperature through the heat exchanger 6 increases.

Thereafter, the control unit 7 also executes the processes of steps S132 to S136 for the second unused ink (= magenta ink) IM and the third unused ink (= yellow ink) IY. Accordingly, the second unused ink IM and the third unused ink IY are also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, if the control part 7 determines with "m = 3" (S136: Yes), it will complete | finish a 2nd circulation process and will return to step S21.

  On the other hand, when the control unit 7 determines that the temperature TK of the used ink IK is not higher than the printing temperature region TP, that is, determines that the temperature TK is lower than the printing temperature region TP (S43: No), the third temperature process is performed. (S46) is executed. The third temperature process in step S46 is the same as the third temperature process shown in step S30 and FIG.

  Next, the control part 7 performs a 3rd circulation process (S47). The third circulation process in step S47 is the same as the third circulation process shown in step S31 and FIG.

(Third circulation processing)
In the third circulation process shown in FIG. 10, first, the control unit 7 executes the processes of steps S150 to S152.

  Next, the control unit 7 determines whether or not the temperature TC of the first unused ink (= cyan ink) IC is lower than the average temperature TA (= TK) of the used ink IK (S153).

Next, when the control unit 7 determines in step S153 that the temperature TC of the first unused ink IC is lower than the average temperature TA of the used ink IK (S153: Yes), the pump of the first unused ink IC. By controlling 13C, the first unused ink IC is circulated at the circulation speed V _LOW (S154). Thereby, the heat transmitted from the used ink IK requiring heating to the first unused ink IC having a low temperature through the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S153 that the temperature TC of the first unused ink IC is not lower than the average temperature TA of the used ink IK (S153: No), the pump of the first unused ink IC is pumped. By controlling 13C, the first unused ink IC is circulated at the circulation speed V _HIGH (S155). As a result, the heat transmitted from the first unused ink IC having a high temperature to the used ink IK requiring heating through the heat exchanger 6 increases.

Thereafter, the control unit 7 also executes the processes of steps S152 to S156 for the second unused ink (= magenta ink) IM and the third unused ink (= yellow ink) IY. Accordingly, the second unused ink IM and the third unused ink IY are also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, in step S156, when the control unit 7 determines that “m = 3” (S156: Yes), the third circulation process is terminated, and the process returns to step S21.

  Thereafter, in the single color pre-printing process shown in FIG. 4, the temperature TK of the ink IK used becomes the printing temperature region TP, and the first circulation process (S24), the second circulation process (S28), and the third circulation process (S31). When any of the above is completed, the control unit 7 ends the monochrome printing pre-processing and executes the monochrome printing process as shown in FIG. 1 (S7).

(Single color printing process)
In the monochromatic printing process, the control unit 7 conveys the printing paper while controlling a conveyance motor (not shown). In this state, the control unit 7 applies a voltage to the electrode of the main body 25K of the inkjet head 17K of the black ink IK based on the image data. Thus, the ink IK is ejected as droplets, and a single color image is printed on the printing paper.

  Next, the control unit 7 determines whether or not the printing is finished based on the image data and the number of printed sheets (S8). If the control unit 7 determines that the printing is not finished (S8: No), it repeats Steps S6 and S7. On the other hand, when the control unit 7 determines that the printing is finished (S8: Yes), the image recording process by the monochromatic printing is finished.

<Special color printing>
In step S5 shown in FIG. 3, when the control unit 7 determines that the printing is not monochrome printing based on the image data (S5: No), the control unit 7 executes the special color printing pre-processing shown in FIG. 11 (S9).

(Spot color pre-processing)
In the special color pre-printing process shown in FIG. 11, the controller 7 first determines whether or not the temperatures TK and TC of all used inks IK and IC are in the printing temperature region TP (S51).

  When the control unit 7 determines that all the inks IK and IC temperatures TK and TC are in the printing temperature region TP (S51: Yes), the ink ink IK and IC average temperature TA is the appropriate temperature region in the printing temperature region TP. It is determined whether or not it is a TPM (S52).

  Next, when the control unit 7 determines that the average temperature TA of the inks IK and IC used is the appropriate temperature region TPM of the printing temperature region TP (S52: Yes), the first temperature process shown in FIG. 5 is executed (S53). ).

(First temperature treatment)
In the first temperature process shown in FIG. 5, the control unit 7 first sets “n = 0” (S101).

  Next, the control unit 7 increments n by “1” to “n = 1” (S102).

  Next, the control unit 7 turns off the heater 14K of the first used ink (= black ink) IK (S103).

  Next, the control unit 7 turns off the fan 21K of the first used ink IK (S104).

  Next, the control unit 7 determines whether or not “n = N” (S105). Here, in the case of spot color printing, since “N = 2”, the control unit 7 determines that “n ≠ N” (S105: No), and returns to Step S102.

  Thereafter, the control unit 7 also executes the processes of steps S102 to S105 for the second used ink (= cyan ink) IC. Thereby, the heater 14 </ b> C and the fan 21 </ b> C of the second used ink IC are also turned off by the control unit 7.

  In step S105, if the control part 7 determines with "n = 2" (S105: Yes), it will complete | finish a 1st temperature process.

  As shown in FIG. 11, when the first temperature process ends, the control unit 7 executes the first circulation process shown in FIG. 6 (S54).

(First circulation process)
In the first circulation process shown in FIG. 6, the controller 7 first controls all the used inks IK and IC pumps 13K and 13C to circulate all the used inks IK and IC at the circulation speed V0 (S110). ).

  Next, the control unit 7 sets “m = 0” (S111).

  Next, the control unit 7 increments m by “1” to “m = 1” (S112).

  Next, the control unit 7 determines whether or not the temperature TM of the first unused ink (= magenta ink) IM is the appropriate temperature region TPM of the printing temperature region TP (S113).

Next, when the control unit 7 determines in step S113 that the temperature TM of the first unused ink IM is the appropriate temperature region TPM of the printing temperature region TP (S113: Yes), the pump of the first unused ink IM is pumped. 13M is controlled to circulate the first unused ink IM at the circulation speed V _HIGH (S114).

On the other hand, when the control unit 7 determines in step S113 that the temperature TM of the first unused ink IM is not the appropriate temperature region TPM of the printing temperature region TP (S113: No), the control unit 7 turns on the pump 13M of the first unused ink IM. By controlling, the first unused ink IM is circulated at the circulation speed V _LOW (S115).

  Next, the control unit 7 determines whether m is “4-N” (S116). Here, in the case of spot color printing, since “N = 2”, “4-N = 2”.

Next, since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to Step S112 (S116: No). Thereafter, the control unit 7 executes the processes of steps S112 to S116 for the second unused ink (= yellow ink) IY. Thereby, the second unused ink IY is also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, in step S116, when the control unit 7 determines that “m = 2” (S116: Yes), the first circulation process ends.

  On the other hand, when the control unit 7 determines in step S52 shown in FIG. 11 that the average temperature TA of the used ink IK and IC is not the appropriate temperature region TPM (S52: No), the average temperature TA of the used ink IK and IC is the printing temperature. It is determined whether or not the region TP is a high temperature region TPH (S56).

  Next, in step S56, when the control unit 7 determines that the average temperature TA of the used inks IK and IC is the higher temperature region TPH of the printing temperature region TP (S56: Yes), the second temperature processing shown in FIG. 7 is executed. (S57).

(Second temperature treatment)
In the second temperature process shown in FIG. 7, the controller 7 first sets “n = 0” (S121).

  Next, the control unit 7 increments n by “1” to “n = 1” (S122).

  Next, the control unit 7 turns off the heater 14K of the first used ink (= black ink) IK (S123).

  Next, the control unit 7 turns on the fan 21K of the first used ink IK (S124).

  Next, the control unit 7 determines whether or not “n = N” (S125). Here, in the case of spot color printing, since “N = 2”, the control unit 7 determines “n ≠ N” (S125: No), and returns to step S122.

  Thereafter, the control unit 7 also performs the processes of steps S122 to S125 for the second used ink (= cyan ink) IC. Thereby, the controller 14 sets the heater 14C of the second used ink IC to off and the fan 21C to on.

  In step S125, when the control unit 7 determines that “n = 2” (S125: Yes), the second temperature process ends.

  As shown in FIG. 11, when the second temperature process is completed, the control unit 7 executes the second circulation process shown in FIG. 8 (S58).

(Second circulation process)
In the second circulation process shown in FIG. 8, the control unit 7 first controls the pumps 13K and 13C of the used inks IK and IC to circulate all the used inks IK and IC at the circulation speed V0 (S130).

  Next, the control unit 7 sets “m = 0” (S131).

  Next, the control unit 7 increments m by “1” to “m = 1” (S132).

  Next, the control unit 7 determines whether or not the temperature TM of the first unused ink (= magenta ink) IM is higher than the average temperature TA of the used ink IK and IC (S133).

Next, when the control unit 7 determines in step S133 that the temperature TM of the first unused ink IM is higher than the average temperature TA of the used ink IK and IC (S133: Yes), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _LOW by controlling the pump 13M (S134). Thereby, the heat transmitted to the used inks IK and IC that require cooling from the first unused ink IM having a high temperature via the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S133 that the temperature TM of the first unused ink IM is not higher than the average temperature TA of the used ink IK and IC (S133: No), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _HIGH by controlling the pump 13M (S135). As a result, the heat transferred from the used inks IK and IC requiring cooling to the first unused ink IM having a low temperature through the heat exchanger 6 increases.

Next, the control unit 7 determines whether m is “4-N” (S136). Here, in the case of spot color printing, since “N = 2”, “4-N = 2”. Since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to step S132 (S136: No). Thereafter, the control unit 7 performs the processes of steps S132 to S136 for the second unused ink (= yellow ink) IY. Thereby, the second unused ink IY is also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, if the control part 7 determines with "m = 2" in step S136 (S136: Yes), it will complete | finish a 2nd circulation process.

  On the other hand, in step S56 shown in FIG. 11, the control unit 7 determines that the average temperature TA of the used inks IK and IC is not the high temperature region TPH of the printing temperature region TP (S56: No), that is, the average of the used inks IK and IC. If it is determined that the temperature TA is the lower temperature region TPL of the printing temperature region TP, the third temperature process shown in FIG. 9 is executed (S60).

(Third temperature treatment)
In the third temperature process shown in FIG. 9, the controller 7 first sets “n = 0” (S141).

  Next, the control unit 7 increments n by “1” to “n = 1” (S142).

  Next, the control unit 7 turns on the heater 14K of the first used ink (= black ink) IK (S143).

  Next, the control unit 7 turns off the fan 21K of the first used ink IK (S144).

  Next, the control unit 7 determines whether or not “n = N” (S145). Here, in the case of spot color printing, since “N = 2”, the control unit 7 determines that “n ≠ N” (S145: No), and returns to step S142.

  Thereafter, the control unit 7 also executes the processes of steps S142 to S145 for the second used ink (= cyan ink). Thereby, the controller 14 sets the heater 14C of the second used ink IC to on and sets the fan 21C to off.

  In step S145, when the control unit 7 determines that “n = 2” (S145: Yes), the third temperature process is ended.

  As shown in FIG. 11, when the third temperature process ends, the control unit 7 executes the third circulation process shown in FIG. 10 (S61).

(Third circulation processing)
In the third circulation process shown in FIG. 10, the control unit 7 first controls the pumps 13K and 13C of the used ink IK and IC to circulate the used ink IK and IC at the circulation speed V0 (S150).

  Next, the control unit 7 sets “m = 0” (S151).

  Next, the control unit 7 increments m by “1” to “m = 1” (S152).

  Next, the control unit 7 determines whether or not the temperature TM of the first unused ink (= magenta ink) IM is lower than the average temperature TA of the used ink IK and IC (S153).

Next, when the control unit 7 determines in step S153 that the temperature TM of the first unused ink IM is lower than the average temperature TA of the used ink IK and IC (S153: Yes), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _LOW by controlling the pump 13M (S154). Thereby, the heat transmitted from the used inks IK and IC that require heating to the first unused ink IM having a low temperature through the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S153 that the temperature TM of the first unused ink IM is not lower than the average temperature TA of the used ink IK and IC (S153: No), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _HIGH by controlling the pump 13M (S155). As a result, the heat transmitted from the first unused ink IM having a high temperature to the used inks IK and IC that require heating increases through the heat exchanger 6.

Next, the control unit 7 determines whether m is “4-N” (S156). Here, in the case of monochrome printing, since “N = 2”, “4-N = 2”. Since “m = 1”, that is, “m ≠ 4-N”, the control unit 7 returns to Step S152 (S156: No). Thereafter, the control unit 7 also performs the processes of steps S152 to S156 for the second unused ink (= yellow ink) IY. Thereby, the second unused ink IY is also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, in step S156, when the control unit 7 determines that “m = 2” (S156: Yes), the third circulation process ends.

  On the other hand, in step S51 shown in FIG. 11, when the control unit 7 determines that any of the used inks IK and IC temperatures TK and TC is not in the printing temperature region TP (S51: No), it determines whether or not printing is in progress. (S71).

  Next, when the control unit 7 determines that printing is in progress (S71: Yes), printing is stopped (S72). Stopping printing includes stopping the conveyance of the printing paper and stopping the application of voltage to the ink jet heads 17K and 17C of the inks IK and IC used.

  Next, the control unit 7 determines whether or not the average temperature TA of the used inks IK and IC is higher than the printing temperature region TP (S73).

  Next, when the control unit 7 determines that the average temperature TA of the used inks IK and IC is higher than the printing temperature region TP (S73: Yes), the control unit 7 executes a second temperature process (S74). The second temperature process in step S74 is the same as the second temperature process shown in step S57 and FIG.

  Next, the control part 7 performs a 2nd circulation process (S75). The second circulation process in step S75 is the same as the second circulation process shown in step S58 and FIG.

(Second circulation process)
In the second circulation process illustrated in FIG. 8, the control unit 7 executes the processes of steps S <b> 130 to S <b> 132.

  Next, the control unit 7 determines whether or not the temperature TM of the first unused ink (= magenta ink) IM is higher than the average temperature TA of the used ink IK and IC (S133).

Next, when the control unit 7 determines in step S133 that the temperature TM of the first unused ink IM is higher than the average temperature TA of the used ink IK and IC (S133: Yes), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _LOW by controlling the pump 13M (S134). Thereby, the heat transmitted to the used inks IK and IC that require cooling from the first unused ink IM having a high temperature via the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S133 that the temperature TM of the first unused ink IM is not higher than the average temperature TA of the used ink IK and IC (S133: No), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _HIGH by controlling the pump 13M (S135). As a result, the heat transferred from the used inks IK and IC requiring cooling to the first unused ink IM having a low temperature through the heat exchanger 6 increases.

Thereafter, the control unit 7 performs the processes of steps S132 to S136 for the second unused ink (= yellow ink) IY. Thereby, the second unused ink IY is also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, if the control part 7 determines with "m = 2" (S136: Yes), it will complete | finish a 2nd circulation process and will return to step S51.

  On the other hand, when the control unit 7 determines that the average temperature TA of the used inks IK and IC is not higher than the printing temperature region TP, that is, the average temperature TA of the used inks IK and IC is lower than the printing temperature region TP (S73). : No), the third temperature process (S76) is executed. The third temperature process in step S76 is the same as the third temperature process shown in step S60 and FIG.

  Next, the control part 7 performs a 3rd circulation process (S77). The third circulation process in step S77 is the same as the third circulation process shown in step S61 and FIG.

(Third circulation processing)
In the third circulation process illustrated in FIG. 10, the control unit 7 performs the processes of steps S150 to S152.

  Next, the control unit 7 determines whether or not the temperature TM of the first unused ink (= magenta ink) IM is lower than the average temperature TA of the used ink IK and IC (S153).

Next, when the control unit 7 determines in step S153 that the temperature TM of the first unused ink IM is lower than the average temperature TA of the used ink IK and IC (S153: Yes), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _LOW by controlling the pump 13M (S154). Thereby, the heat transmitted from the used inks IK and IC that require heating to the first unused ink IM having a low temperature through the heat exchanger 6 is reduced.

On the other hand, when the control unit 7 determines in step S153 that the temperature TM of the first unused ink IM is not lower than the average temperature TA of the used ink IK and IC (S153: No), the first unused ink IM. The first unused ink IM is circulated at the circulation speed V _HIGH by controlling the pump 13M (S155). As a result, the heat transmitted from the first unused ink IM having a high temperature to the used inks IK and IC that require heating increases through the heat exchanger 6.

Thereafter, the control unit 7 also performs the processes of steps S152 to S156 for the second unused ink (= yellow ink) IY. Thereby, the second unused ink IY is also circulated at a predetermined circulation speed (V _HIGH or V _LOW ).

  Next, if the control part 7 determines with "m = 2" (S156: Yes), it will complete | finish a 3rd circulation process and will return to step S51.

  Thereafter, in the special color pre-printing process shown in FIG. 11, the temperatures TK and TC of all the inks IK and IC become the printing temperature region TP, and the first circulation process (S54), the second circulation process (S58), and the first When one of the three circulation processes (S61) ends, the control unit 7 ends the special color pre-printing process, and the special color printing process is executed as shown in FIG. 3 (S10).

(Special color printing process)
In the special color printing process, the control unit 7 conveys the printing paper while controlling the conveyance motor. In this state, the control unit 7 applies a voltage to the electrodes of the main body portions 25K and 25C of the black and cyan inks IK and IC inkjet heads 17K and 17C based on the image data. Accordingly, the inks IK and IC are ejected as droplets, and a two-color image is printed on the printing paper.

  Next, the control unit 7 determines whether or not the printing is finished based on the image data and the number of printed sheets (S11). If the control unit 7 determines that the printing is not finished (S11: No), the control unit 7 repeats Step S9 and Step S10. On the other hand, when the control unit 7 determines that the printing is finished (S11: Yes), the image recording process by the spot color printing is finished.

  Next, effects of the image recording apparatus 1 according to the first embodiment described above will be described.

  As described above, in the image recording apparatus 1, the control unit 7 controls the circulation speed of the unused ink I based on the comparison result between the average temperature TA of the used ink I and the temperature T of the unused ink I. As a result, the image recording apparatus 1 can suppress the unnecessary conduction of heat from the used ink I to the unused ink I and the unnecessary conduction of heat from the unused ink I to the used ink I. As a result, the image recording apparatus 1 can shorten the time required for the used ink I to reach the printing temperature region TP, thereby shortening the startup time until printing.

Specifically, when the average temperature TA of the used ink I is lower than the printing temperature region TP, the control unit 7 replaces the unused ink I having a temperature higher than the average temperature TA with the circulation speed V0 or more of the used ink I. It circulates with the circulation speed _VHIGH . Accordingly, more heat is transferred from the unused ink I to the used ink I that needs to be heated lower than the printing temperature region TP via the heat exchanger 6. For this reason, the used ink I can be heated efficiently. As a result, the image recording apparatus 1 can shorten the time until the used ink I reaches the printing temperature region TP, and therefore the activation time until printing can be shortened.

When the average temperature TA of the used ink I is lower than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA as a circulation speed lower than the circulation speed V0 of the used ink I. Circulate with V _LOW . Thereby, it can suppress that heat transfers to the unused ink I from the used ink I which needs to be heated lower than the printing temperature range TP via the heat exchanger 6. For this reason, the used ink I can be heated efficiently. As a result, the image recording apparatus 1 can shorten the time until the used ink I reaches the printing temperature region TP, and therefore the activation time until printing can be shortened.

Further, when the average temperature TA of the used ink I is higher than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is higher than the average temperature TA as a circulation speed lower than the circulation speed V0 of the used ink I. Circulate with V _LOW . Thereby, it is possible to suppress the transfer of heat from the unused ink I to the used ink I that needs to be cooled higher than the printing temperature region TP via the heat exchanger 6. For this reason, the used ink I can be cooled efficiently. As a result, the image recording apparatus 1 can shorten the time until the used ink I reaches the printing temperature region TP, and therefore the activation time until printing can be shortened.

When the average temperature TA of the used ink I is higher than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA as a circulation speed equal to or higher than the circulation speed V0 of the used ink I. Circulate with V _HIGH . As a result, more heat is transferred from the used ink I that needs to be cooled to a temperature higher than the printing temperature region TP to the unused ink I through the heat exchanger 6. For this reason, the used ink I can be cooled efficiently. As a result, the image recording apparatus 1 can shorten the time until the used ink I reaches the printing temperature region TP, and therefore the activation time until printing can be shortened.

  Furthermore, in the image recording apparatus 1, even when all the used inks I are in the printing temperature region TP, the control unit 7 is based on the comparison result between the average temperature TA of the used ink I and the temperature T of the unused ink I. The circulation speed of the unused ink I is controlled. As a result, the image recording apparatus 1 can efficiently maintain the used ink I in the printing temperature region TP.

Specifically, when the average temperature TA of the used ink I is the lower temperature region TPL of the printing temperature region TP, the control unit 7 circulates the unused ink I whose temperature is higher than the average temperature TA, by circulating the used ink I. Circulation is performed at a circulation speed V _HIGH higher than the speed V0. As a result, more heat is transferred from the unused ink I to the used ink I, which is the lower temperature region TPL of the printing temperature region TP, via the heat exchanger 6. As a result, since the image recording apparatus 1 can heat the used ink I with the unused ink I, the used ink I can be efficiently maintained in the printing temperature region TP.

When the average temperature TA of the used ink I is the lower temperature region TPL of the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA as less than the circulation speed V0 of the used ink I. Circulation is performed at a circulation speed V _LOW of. Thereby, it is possible to suppress the transfer of heat from the used ink I which is the lower temperature region TPL of the printing temperature region TP to the unused ink I via the heat exchanger 6. As a result, the image recording apparatus 1 can suppress the used ink I from being cooled by the unused ink I, so that the used ink I can be efficiently maintained in the printing temperature region TP.

Further, when the average temperature TA of the used ink I is a temperature range TPH that is higher than the printing temperature region TP, the control unit 7 replaces the unused ink I having a temperature higher than the average temperature TA with less than the circulation speed V0 of the used ink I. Circulation is performed at a circulation speed V _LOW of. Thereby, it is possible to suppress the transfer of heat from the unused ink I to the used ink I which is the higher temperature region TPH of the printing temperature region TP via the heat exchanger 6. As a result, since the image recording apparatus 1 can suppress the used ink I from being heated by the unused ink I, the used ink I can be efficiently maintained in the printing temperature region TP.

Further, when the average temperature TA of the used ink I is a temperature range TPH that is higher than the printing temperature region TP, the control unit 7 uses the unused ink I whose temperature is lower than the average temperature TA as the circulation speed V0 or more of the used ink I. It circulates with the circulation speed _VHIGH . As a result, more heat is transferred from the used ink I, which is the higher temperature region TPH of the printing temperature region TP, to the unused ink I via the heat exchanger 6. As a result, since the image recording apparatus 1 can cool the used ink I with the unused ink I, the used ink I can be efficiently maintained in the printing temperature region TP.

When the average temperature TA of the used ink I is the appropriate temperature region TPM in the printing temperature region TP, the control unit 7 circulates the unused ink I whose temperature is in the appropriate temperature region TPM at the circulation speed V0 or more of the used ink I. Circulate at speed V _HIGH . Thereby, the temperature of the used ink I and the unused ink I is averaged. As a result, since the image recording apparatus 1 can suppress the temperature change of the used ink I that is the appropriate temperature region TPM, the used ink I can be efficiently maintained in the printing temperature region TP.

When the average temperature TA of the used ink I is the appropriate temperature region TPM in the printing temperature region TP, the control unit 7 converts the unused ink I whose temperature is not the appropriate temperature region TPM to a circulation speed lower than the circulation speed V0 of the used ink I. Circulate with V _LOW . Thereby, it can suppress that heat transfers between the used ink I and the unused ink I via the heat exchanger 6. FIG. As a result, since the image recording apparatus 1 can suppress the temperature change of the used ink I that is the appropriate temperature region TPM, the used ink I can be efficiently maintained in the printing temperature region TP.

  Moreover, the control part 2 controls the heater 14 and the fan 21 of each ink circulation mechanism 2-5 separately. Thereby, the image recording apparatus 1 can efficiently maintain the used ink I in the printing temperature region TP.

(Second Embodiment)
Next, a second embodiment in which the black ink ink circulation mechanism of the above-described embodiment is changed will be described. FIG. 12 is a block diagram illustrating a control system of the image recording apparatus according to the second embodiment. In addition, the same code | symbol is attached | subjected to the structure similar to embodiment mentioned above, and description is abbreviate | omitted.

  As shown in FIG. 12, the ink circulation mechanism 2A of the image recording apparatus 1A includes four heaters 14K1 to 14K4.

  The controller 7A of the image recording apparatus 1A sets the temperature TK of the black ink IK in the printing temperature region TP by switching on and off the four heaters 14K1 to 14K4 in the monochrome printing with the black ink IK.

  In the all color printing, the controller 7A switches on / off only the heater 14K1 and sets the temperature TK of the black ink IK in the printing temperature region TP. The controller 7A sets the heaters 14K2 to 14K4 to off in all color printing.

  The controller 7A controls the remaining three color inks IC, IM, and IY heaters 14C, 14M, and 14Y in the same manner as in the first embodiment.

  In the image recording apparatus 1A according to the second embodiment, by providing the four heaters 14K1 to 14K4 in the black ink circulation mechanism 2A that is frequently used, it is possible to reduce the startup time in monochromatic printing.

  Further, in the image recording apparatus 1A, the three heaters 14K2 to 14K4 of the black ink circulation mechanism 2A are set to OFF during the printing of all colors, so that the remaining three colors of ink IC, IM, and IY can be obtained. An increase in the time required to reach the printing temperature region TP can be suppressed.

  As mentioned above, although this invention was demonstrated in detail using embodiment, this invention is not limited to embodiment described in this specification. The scope of the present invention is determined by the description of the scope of claims and the scope equivalent to the description of the scope of claims. Hereinafter, modified embodiments in which the above-described embodiment is partially modified will be described.

  The numerical values, materials, colors, shapes, and the like shown in the above-described embodiments can be changed as appropriate.

  In the above-described embodiment, the present invention is applied to a four-color image recording apparatus. However, the present invention may be applied to an image recording apparatus having two colors, three colors, and five or more colors. Further, the present invention may be applied to an image recording apparatus that circulates the same color ink through a plurality of ink circulation mechanisms.

  In the above-described embodiment, the present invention is applied to an image recording apparatus including an inkjet head having a piezoelectric element. However, the present invention may be applied to other image recording apparatuses including an ink circulation mechanism.

  In the above-described embodiment, black monochromatic printing has been described as an example, but monochromatic printing may be performed using a color other than black. Further, although the special color printing with two colors of black and cyan is shown as an example, the special color printing may be performed with other two colors or three colors.

In the above-described embodiment, the circulation speed V _LOW is lower than the circulation speed V 0, but “V _LOW = 0”, that is, the circulation at the circulation speed V _LOW is configured so that the circulation stops. Also good.

In the embodiment described above, the circulation speed of the unused ink is set to V _HIGH or V _LOW regardless of the temperature difference between the average temperature of the used ink and the temperature of the unused ink. _HIGH and a plurality of V _LOW may be set. For example, the circulation speed when the temperature difference is large may be V _HIGH1, and the circulation speed when the temperature difference is small may be V _HIGH2 (<V _HIGH1 ). Further, the circulation speed when the temperature difference is large may be V _LOW1, and the circulation speed when the temperature difference is small may be V _LOW2 (> V _LOW1 ).

  The printing temperature region, the upper limit temperature and the lower limit temperature of the printing temperature region, the temperature constant, and the like given in the above-described embodiment are examples, and can be appropriately changed depending on the ink material and the like. For example, the printing temperature region can be appropriately changed depending on the ink material. Further, the temperature constant α can be appropriately changed between 0 <α <0.5.

  In the above-described embodiment, the on / off control of the fan of the heater and the cooler is an example, and can be changed as appropriate. For example, when the temperature of the ink used can be maintained in the printing temperature range only by heat exchange by the heat exchanger, the heater and the fan may be turned off.

In the embodiment described above, the circulation speed of the unused ink is controlled to V _HIGH or V _{LOW even} when the temperature of the used ink is in the printing temperature range. However, when the temperature of the used ink is in the printing temperature range, the unused ink is not used. The ink circulation speed may be uniformly controlled to the same V0 as the ink used.

1, 1A Image recording devices 2 to 5, 2A Ink circulation mechanism 6 Heat exchanger 7, 7A Control units 11K, 11C, 11M, 11Y Ink bottles 12K, 12C, 12M, 12Y Lower tanks 13K, 13C, 13M, 13Y Pump 14K , 14C, 14M, 14Y Heater 14K1-14K4 Heater 15K, 15C, 15M, 15Y Cooler 16K, 16C, 16M, 16Y Upper tank 17K, 17C, 17M, 17Y Inkjet head 18K, 18C, 18M, 18Y Piping 21K, 21C, 21M, 21Y Fans 22K, 22C, 22M, 22Y Heat sinks 25K, 25C, 25M, 25Y Body portions 26K, 26C, 26M, 26Y Temperature detectors 27K, 27C, 27M, 27Y Driver 31 CPU
32 RAM
33 ROM
34 I / O port 90 Input section I, IK, IC, IM, IY Ink TA Average ink temperature T, TK, TC, TM, TY Ink temperature TP Printing temperature range TPH Higher printing temperature range TPL printing Lower temperature range Temperature range TPM Suitable temperature range for printing temperature range V0 Circulation speed V _HIGH Circulation speed V _LOW Circulation speed

Claims (6)

Q units each having a circulation means for circulating ink, a temperature detection unit for detecting the temperature of the ink and outputting it as information, and an inkjet head for discharging the circulating ink onto a recording medium to form an image The ink circulation mechanism,
A heat exchanger provided so as to straddle the middle part of the Q ink circulation mechanisms, and for exchanging heat between the inks;
A temperature control unit that receives the ink temperature information from the temperature detection unit and controls the circulation speed of the ink by the circulation unit;
The controller is
N is 1 ≦ N ≦ Q−1 and an integer,
When printing N inks as used,
If any of the temperatures of at least the N used inks is not in the printing temperature range,
An image recording apparatus, wherein the circulation speed of each unused ink is controlled by the circulation means based on a comparison result between the average temperature TA of the N used inks and the temperature of the unused ink. The controller is
When the average temperature TA of the N inks used is lower than the printing temperature range,
The image recording apparatus according to claim 1, wherein unused ink having a temperature higher than an average temperature TA of the N used inks is circulated at a speed higher than a circulation speed of the used ink. The controller is
When the average temperature TA of the N inks used is lower than the printing temperature range,
3. The image recording apparatus according to claim 1, wherein unused ink having a temperature lower than an average temperature TA of the N used inks is circulated at a speed lower than a circulation speed of the used ink. The controller is
When the average temperature TA of the N inks used is higher than the printing temperature range,
The image according to any one of claims 1 to 3, wherein unused ink having a temperature higher than an average temperature TA of the N used inks is circulated at a speed lower than a circulation speed of the used ink. Recording device. The controller is
When the average temperature TA of the N inks used is higher than the printing temperature range,
The image according to any one of claims 1 to 4, wherein unused ink having a temperature lower than an average temperature TA of the N used inks is circulated at a circulation speed of the used ink or more. Recording device. Each ink circulation mechanism includes a heating means or a cooling means,
The image recording apparatus according to claim 1, wherein the control unit controls the heating unit or the cooling unit for each ink circulation mechanism.