Printer

Abstract

To provide a printer capable of suppressing discharge failure of ink.SOLUTION: A controller executes: a pass operation in which ink is ejected from the nozzles onto a partial area of the printing medium while moving the head based on image data; a printing process of performing a recording step including a transport operation of transporting a print medium; a gap acquisition process of acquiring the size of the gap between the print medium and the ejection surface; a temperature acquisition process of acquiring temperature information of the head based on the temperature detected by the temperature sensor; a method determining process of determining, for each recording process, whether the recording process is a single-pass method or a multi-pass method based on the reference value, the gap size, and the temperature information; and a calculation process of calculating a reference value of a partial region based on image data.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a printing apparatus using a serial head system.

Background Art

[0002] As a conventional printing apparatus, for example, a recording apparatus disclosed in Patent Document 1 is known. This recording apparatus includes a recording head having nozzles for discharging liquid, and a moving device for reciprocating the recording head.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described recording apparatus, while the recording head reciprocates on the recording medium, liquid is discharged from the nozzles to print an image on the storage medium. In this printing process, airflow is generated by the movement of the recording head and the discharge of the liquid, and the mist of the liquid diffuses due to the airflow and may adhere to the recording head. In this case, there is a risk of causing poor discharge of the liquid from the nozzles due to the adhered liquid.

[0005] In view of such a situation, an object of the present disclosure is to provide a printing apparatus capable of suppressing poor discharge of ink caused by adhered ink on the discharge surface.

Means for Solving the Problems

[0006] A printing apparatus according to an aspect of the present disclosure includes a plurality of nozzles that eject ink onto a printing medium, a head having a discharge surface through which the plurality of nozzles open, a moving device that moves the head, a conveying device that conveys the printing medium in a direction intersecting the moving direction of the head, a temperature sensor that detects temperature, and a control device. The control device performs a printing process including a recording process that includes a pass operation of ejecting ink from the nozzles to a partial area of the printing medium while moving the head based on image data and a conveying operation of conveying the printing medium, a gap acquisition process of acquiring a dimension of a gap between the printing medium and the discharge surface, a temperature acquisition process of acquiring temperature information of the head based on a detected temperature by the temperature sensor, and for each recording process, based on a reference value, the dimension of the gap, and the temperature information, determining a method of the recording process as either a single-pass method of performing the pass operation on one partial area of the printing medium or a multi-pass method of complementarily performing the pass operation a plurality of times on one partial area of the printing medium and having a smaller number of ink ejection times per unit time than the single-pass method, and a calculation process of calculating the reference value of the partial area based on the image data.

[0007] A printing apparatus according to another aspect of the present disclosure includes a plurality of nozzles that eject ink onto a printing medium, a head having a discharge surface through which the plurality of nozzles open, a moving device that moves the head, a conveyance device that conveys the printing medium in a direction intersecting the moving direction of the head, a temperature sensor that detects temperature, a maintenance unit that maintains the nozzles, and a control device. The control device performs a printing process including a pass operation of ejecting ink from the nozzles to a partial area of the printing medium while moving the head based on image data, and a conveyance operation of conveying the printing medium, a gap acquisition process of acquiring a dimension of a gap between the printing medium and the discharge surface, a temperature acquisition process of acquiring temperature information of the head based on the detected temperature by the temperature sensor, a maintenance process of maintaining the nozzles by the maintenance unit after the execution of the pass operation based on a reference value, the dimension of the gap, and the temperature information, and a calculation process of calculating the reference value of the partial area based on the image data.

[0008] A printing apparatus according to still another aspect of the present disclosure includes a plurality of nozzles that eject ink onto a printing medium, a head having a discharge surface through which the plurality of nozzles open, a moving device that moves the head, a conveying device that conveys the printing medium in a direction intersecting the moving direction of the head, a temperature sensor that detects temperature, a wiper that wipes the discharge surface, a cap that covers the discharge surface, a suction pump that sucks the space surrounded by the discharge surface and the cap, and a control device. The control device performs a maintenance process including a purge process of ejecting ink from the nozzles by the suction pump and a wiping process of wiping the discharge surface by the wiper, a pass operation of ejecting ink from the nozzles to a partial area of the printing medium while moving the head based on image data, a conveyance operation of conveying the printing medium, a gap acquisition process of acquiring the dimension of the gap between the printing medium and the discharge surface, a temperature acquisition process of acquiring temperature information of the head based on the detected temperature by the temperature sensor, a purge process or the wiping process as the maintenance process to be executed after the execution of the pass operation based on a reference value, the dimension of the gap, and the temperature information, and a calculation process of calculating the reference value of the partial area based on the image data.

Advantages of the Invention

[0009] The larger the dimension of the gap between the discharge surface of the head and the printing medium, the larger the amount of ink mist that floats without reaching the printing medium. Also, the lower the temperature of the head, the easier it is for an air flow to be generated by the ejection of ink from the head. Under conditions where the amount of ink adhering to the discharge surface tends to increase due to such an air flow, by executing a recording process in a multi-pass method with a small number of ink ejection times per unit time, the amount of mist and the amount of air flow can be reduced, and ink ejection failure caused by the adhering ink on the discharge surface can be suppressed. Also, under conditions where the amount of ink adhering to the discharge surface tends to increase due to an air flow, by executing a maintenance process for the nozzles that open on the discharge surface, ink ejection failure caused by the adhering ink on the discharge surface can be suppressed.

[0010] Hereinafter, embodiments according to the present disclosure will be specifically described with reference to the drawings. In the following, the same or corresponding elements throughout all the drawings will be given the same reference numerals, and redundant descriptions will be omitted.

Brief Explanation of the Drawings

[0011]

Figure 1

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Figure 10

Figure 11

Modes for Carrying Out the Invention

[0012] (Embodiment 1) <Printing Apparatus> As shown in FIG. 1, the printing apparatus 10 according to Embodiment 1 of the present disclosure is an apparatus that discharges ink from the head 20 onto the print medium A while moving the head 20 in the moving direction, and prints an image on the print medium A. For example, it is an inkjet printer using the serial head method. The print medium A is, for example, a sheet such as paper and fabric.

[0013] Hereinafter, the moving direction in which the head 20 moves is referred to as the left - right direction. The direction that intersects (for example, is orthogonal to) this moving direction and in which the print medium A is conveyed is referred to as the front - rear direction. Also, the direction that intersects (for example, is orthogonal to) the moving direction of the head 20 and the conveying direction of the print medium A is referred to as the up - down direction. However, the directions related to the printing apparatus 10 are not limited to this.

[0014] The printing apparatus 10 includes a head 20. The head 20 has a plurality of nozzles 21 and a plurality of drive elements 22 (FIG. 2). The plurality of nozzles 21 are arranged in the front - rear direction to form a nozzle row. The nozzles 21 open to the ejection surface 23 which is the lower surface of the head 20. The drive elements 22 are piezoelectric elements, heating elements, electrostatic actuators, etc., and are provided for each nozzle 21, and apply ejection energy such as pressure for ejecting ink from the nozzles 21 to the ink in the head 20.

[0015] Furthermore, the printing apparatus 10 includes a platen 11. The platen 11 is positioned at a predetermined distance below the head 20. The flat upper surface of the platen 11 is arranged to face the ejection surface 23 of the head 20 and supports the print medium A from below.

[0016] Furthermore, the printing apparatus 10 includes a moving device 30 that moves the head 20. The moving device 30 includes a carriage 31, two guide rails 32, an endless belt 33, and a moving motor 34. The carriage 31 has a box shape and mounts the head 20. The two guide rails 32 extend horizontally to cross over the platen 11 disposed directly below, and are arranged apart from each other in the front-rear direction so as to sandwich all the nozzles 21 therebetween, and support the carriage 31 movably. The endless belt 33 is connected to the carriage 31 and is connected to the moving motor 34 via a pulley 35 provided on the guide rail 32. Therefore, when the moving motor 34 is rotationally driven, the endless belt 33 runs, and the carriage 31 and the head 20 supported by the carriage 31 are moved in the left-right direction along the guide rail 32.

[0017] Furthermore, the printing apparatus 10 includes a conveying device 40 that conveys the printing medium A. The conveying device 40 includes, for example, a conveying roller 41 and a conveying motor 42 (FIG. 2). The conveying roller 41 has a shaft extending in the left-right direction, and the conveying motor 42 is connected to the shaft of the conveying roller 41. When the conveying motor 42 is rotationally driven, the conveying device 40 rotates the conveying roller 41 about its shaft and conveys the printing medium A in the front-rear direction on the platen 11.

[0018] Furthermore, as shown in FIG. 2, the printing apparatus 10 includes a control device 50, and a communication interface 53, an input device 12, a temperature sensor 13, a distance measuring sensor 14, a head drive circuit 54, a moving drive circuit 55, and a conveying drive circuit 56 that are electrically connected to the control device 50. The communication interface 53 is a connecting device that connects to an external device existing independently from outside the printing apparatus 10, and may be connected to the external device by wired communication such as a USB cable or wireless communication such as a LAN. Examples of the external device include a computer, a mobile terminal, a server, a storage medium, and a communication network. Thereby, the control device 50 acquires data such as image data from the external device via the communication interface 53. The image data is data representing an image to be printed, and is, for example, raster data.

[0019] The input device 12 is a device that inputs data to the control device 50, and a push button, a pointing device, etc. are used. Note that a communication interface 53 may be used as the input device 12.

[0020] The temperature sensor 13 detects the temperature of the head 20 and outputs the detected temperature to the control device 50. Note that when there is a difference between the detected temperature by the temperature sensor 13 and the temperature of the head 20, the control device 50 may correct the detected temperature and acquire it as the temperature of the head 20.

[0021] Further, the distance measuring sensor 14 detects the dimension G of the gap between the ejection surface 23 of the head 20 and the printed medium A facing the ejection surface 23, and outputs the dimension G to the control device 50. Note that when the dimension of the printed medium A is input by the communication interface 53 or the input device 12, the control device 50 may acquire the dimension G of the gap between the ejection surface 23 and the printed medium A based on the dimension, and the predetermined positions of the ejection surface 23 and the upper surface of the platen 11.

[0022] The control device 50 is constituted by, for example, a computer and has an arithmetic processing unit 51 and a storage unit 52. The storage unit 52 is a memory accessible from the arithmetic processing unit 51 and has at least one of, for example, RAM, ROM, E2PROM, and NVRAM. The storage unit 52 stores the data input from the communication interface 53 and the input device 12, and the computer program and various data used for data processing by the arithmetic processing unit 51.

[0023] The arithmetic processing unit 51 includes, for example, a processor such as a CPU, an integrated circuit such as an ASIC, or both circuits. The control device 50 controls the operations of each part of the printing device 10 by executing a computer program while referring to the detection signals from the temperature sensor 13 and the distance measurement sensor 14 and the stored data in the storage unit 52. Note that the control device 50 may be constituted by a single device, or a plurality of devices may be distributed and configured to cooperate to perform the operations of the control device 50.

[0024] The head drive circuit 54 is electrically connected to the drive element 22 of the head 20. The control device 50 generates a control signal for driving the drive element 22 based on image data or the like, and the head drive circuit 54 generates a drive signal based on this control signal. Then, the drive element 22 is driven based on the drive signal so as to apply ejection energy to the ink in the head 20 at the ejection timing based on the image data. As a result, ink droplets are ejected from the nozzles 21 of the head 20.

[0025] The movement drive circuit 55 is electrically connected to the movement motor 34 of the movement device 30. The control device 50 generates a control signal for driving the movement motor 34 based on image data or the like, and the movement drive circuit 55 generates a drive signal based on this control signal. Then, the movement motor 34 drives the carriage 31 that supports the head 20 to move in the left - right direction at a variable speed and stops the carriage 31 at an arbitrary position within its movable range based on the drive signal.

[0026] The conveyance drive circuit 56 is electrically connected to the conveyance motor 42 of the conveyance device 40. The control device 50 generates a control signal for driving the conveyance motor 42 based on image data or the like, and the conveyance drive circuit 56 generates a drive signal based on this control signal. Then, the conveyance motor 42 drives the printed medium A on the platen 11 to be conveyed intermittently or continuously in the front - rear direction and stops the printed medium A at a predetermined position on the platen 11 based on the drive signal.

[0027] <Printing Process> The control device 50 executes a printing process based on the image data of the printing image which is the image to be printed. The printing process includes one or more recording steps, and the recording step includes a pass operation and a conveyance operation. As shown in FIG. 5, in the pass operation, the control device 50 discharges ink from the nozzles 21 to the partial area P of the medium A to be printed while moving the head 20 in the left-right direction based on the image data. Thereby, dots are formed in the partial area P, and a partial image composed of the dots is formed. In the conveyance operation, the control device 50 conveys the medium A to be printed by a predetermined conveyance amount in the front-rear direction. By alternately repeating this pass operation and conveyance operation, a plurality of partial images are arranged in the front-rear direction on the medium A to be printed, and a printing image composed of the plurality of partial images is printed on the medium A to be printed.

[0028] The partial area P is a part of the medium A to be printed and is the area of the medium A to be printed targeted by one recording step. The partial image data is the data used in one recording step among the image data of the printing image and represents the partial image which is the image formed in the partial area P by one recording step.

[0029] The recording step methods include a single-pass method and a multi-pass method. The recording step of the single-pass method performs one pass operation on one partial area P of the medium A to be printed, and forms one partial image in the partial area P based on the partial image data by one pass operation.

[0030] Also, the recording step of the multi-pass method complementarily performs a plurality of (M (an integer of 2 or more) times) pass operations on one partial area P of the medium A to be printed. Note that a conveyance operation may be executed between the pass operations in one recording step. In this case, the conveyance amount of the medium A to be printed by the conveyance operation is smaller than the conveyance amount of the medium A to be printed by the conveyance operation in a single pass.

[0031] By attaching a mask to the partial image data for the recording process, it is divided into a plurality of first to Mth pass partial image data, and the first to Mth pass partial image data are respectively assigned to the first to Mth pass operations. Each of the first to Mth pass operations is executed based on the assigned first to Mth pass partial image data, and first to Mth pass partial images are formed. Since a mask with a predetermined application rate is overall attached to each of the first to Mth pass partial image data, a plurality of pass partial images overlap to form the partial image targeted for the recording process.

[0032] For example, when M = 2, a mask is attached to the partial image data of the recording process shown in FIG. 11, and the partial image data is divided into first pass partial image data representing the first pass partial image and second pass partial image data representing the second pass partial image. At this time, data with a mask attached to pixel "2" of the partial image data is generated as the first pass partial image data, and data with a mask attached to pixel "1" of the partial image data is generated as the second pass partial image data.

[0033] According to the pass operation based on this first pass partial image data, dots of the first pass partial image are formed at the dot formation pixel "1", and dots of the first pass partial image are not formed at the mask pixel "2". On the other hand, according to the pass operation based on the second pass partial image data, dots of the second pass partial image are formed at the dot formation pixel "2", and dots of the second pass partial image are not formed at the mask pixel "1". By overlapping this first pass partial image and the second pass partial image, dots of the second pass partial image are formed at the mask positions where dots of the first pass partial image are not formed, and dots of the first pass partial image are formed at the mask positions where dots of the second pass partial image are not formed. Therefore, the first pass partial image and the second pass partial image complement each other to form the partial image targeted for the recording process.

[0034] In the path partial image data, the application rate of the mask may be changed in the front-back direction. This application rate is the ratio of the number of pixels with a mask to the number of a plurality of pixels arranged in the left-right direction in the partial image data. For example, 210 pixels are arranged in the front-back direction in the partial image data. In this case, for the 70 pixels in the front part of the partial image data, a mask with an application rate of less than 50% and decreasing towards the front is applied, for the 70 pixels in the rear part, a mask with an application rate of less than 50% and increasing towards the rear is applied, and for the 70 pixels in the central part between the front part and the rear part, a mask with an application rate of 50% is applied, whereby the first partial image data is formed. On the other hand, in the partial image data, in order to complement the first path partial image data, a mask is applied to the pixels not masked by the first path partial image data, whereby the second partial image data is formed. Therefore, the first path partial image based on the first partial image data and the second path partial image based on the second partial image data are overlapped to form the partial image to be the target of the recording process.

[0035] As described above, according to the multi-pass recording process, a plurality of path partial images are overlapped in the partial region P to form a partial image. As a result, the number of dots constituting each path partial image is less than the number of dots constituting the partial image. These dots are formed by the ink ejected from the nozzle 21 by the path operation. Therefore, the number of ink ejection times per unit time by each path operation of the multi-pass method is less than the number of ink ejection times per unit time by one path operation of the single-pass method.

[0036] In the recording process of the single-pass method, a part of the partial image formed by the pass operation may overlap with a part of another partial image. Even in such a case, a mask with a predetermined application rate is attached to a part of the partial image data of the single-pass method, while a mask with a predetermined application rate (for example, greater than 0% and less than 100%) is attached to all of the pass partial image data of the multi-pass method. For this reason, at least a part of the partial image of the single-pass method does not overlap with other partial images. On the other hand, all of the pass partial images of the multi-pass method overlap with other pass partial images. For this reason, the number of ink discharges per unit time by each pass operation of the multi-pass method is less than the number of ink discharges per unit time by one pass operation of the single-pass method.

[0037] <Method determination process> As described above, the recording process is executed by the single-pass method or the multi-pass method, and this method is determined as follows. As shown in FIG. 3, in the pass operation of the recording process, an air flow (moving air flow) is generated by the movement of the head 20, and an air flow (discharge air flow) is generated by the discharge of ink from the nozzles 21 of the head 20. As a result, in the gap between the discharge surface 23 of the head 20 and the printing medium A, an air flow combining the moving air flow and the discharge air flow is generated. If the mist of the ink discharged from the nozzle 21 diffuses and adheres to the discharge surface 23 due to this air flow, there is a risk of causing poor ink discharge from the nozzle 21 due to the adhered ink.

[0038] Therefore, in order to reduce poor ink discharge, the control device 50 executes a method determination process for determining whether the recording process is the single-pass method or the multi-pass method based on a reference value, the dimension G of the gap, and temperature information for each recording process. The reference value is, for example, the printing duty of the scan area S (FIG. 5) which is a part of the partial area P. The calculation process for calculating this reference value will be described later.

[0039] The larger the printing duty of the scan area S is, the greater the number of dots formed in the scan area S becomes, and the greater the number of ink ejection times per unit time in the pass operation becomes. As a result, the amount of ink mist and the air flow rate that float increase, the ink mist diffuses due to the air flow, and the ink mist easily adheres to the ejection surface 23. Under the condition that the amount of ink adhesion on the ejection surface 23 tends to increase due to such an air flow, a multi-pass method with a small number of ink ejection times per unit time in the pass operation is used as the method of the recording process. Thereby, in order to reduce the amount of ink mist and the air flow rate and reduce the amount of ink adhesion on the ejection surface 23, it is possible to suppress ink ejection failure caused by the adhered ink on the ejection surface 23.

[0040] Also, the larger the dimension G of the gap is, the greater the amount of ink mist that floats without reaching the printing medium A becomes. When the temperature of the head 20 is used as temperature information, the lower the temperature of this head 20 is, the higher the viscosity of the ink in the head 20 becomes. For this reason, the ejection energy applied to the ink in the head 20 increases, the ink ejection speed increases, and an ejection air flow is likely to occur.

[0041] Thus, when the amount of ink mist is large and an air flow is likely to occur, the ink mist diffuses due to the air flow and easily adheres to the ejection surface 23. Under the condition that the amount of ink adhesion on the ejection surface 23 tends to increase due to such an air flow, a multi-pass method with a small number of ink ejection times per unit time in the pass operation is used as the method of the recording process. Thereby, in order to reduce the amount of ink mist and the air flow rate and reduce the amount of ink adhesion on the ejection surface 23, it is possible to suppress ink ejection failure caused by the adhered ink on the ejection surface 23.

[0042] On the other hand, under the condition that the amount of ink adhesion on the ejection surface 23 is less likely to increase due to the air flow, a single-pass method is used as the method of the recording process. Thereby, the number of pass operations in the recording process can be reduced, and the prolongation of the printing time can be reduced.

[0043] <Duty determination process> In the method determination process for determining such a recording process method, for example, the determination result of the duty determination process is used. The duty determination process is a process for determining whether the printing duty of the scan area S is equal to or greater than the threshold value h, and the threshold value h is determined based on the dimension G of the gap and the temperature of the head 20. Note that the threshold value acquisition process for this threshold value h will be described later.

[0044] If the printing duty of the scan area S is equal to or greater than the threshold value in the duty determination process, it is a condition where the amount of ink adhesion on the ejection surface 23 tends to increase due to the airflow. Therefore, in the method determination process, the recording process method is determined to be the multi-pass method. Also, if the printing duty of the scan area S is less than the threshold value in the duty determination process, it is a condition where the amount of ink adhesion on the ejection surface 23 tends not to increase due to the airflow. Therefore, in the method determination process, the recording process method is determined to be the single-pass method.

[0045] <Threshold value acquisition process> Regarding the threshold value h of this duty determination process, the control device 50 executes a threshold value acquisition process for acquiring the threshold value based on the dimension G of the gap and the temperature of the head 20. For example, the threshold value h is represented by (h0 × k), where h0 is a predetermined value and k (%) is a coefficient.

[0046] As shown in FIG. 4, this coefficient k is determined in advance based on the temperature T of the head 20 and the dimension G of the gap. The temperature T of the head 20 is divided into a low temperature (T < T1) less than the first predetermined temperature T1, a medium temperature (T1 ≤ T < T2) equal to or greater than the first predetermined temperature T1 and less than the second predetermined temperature T2, and a high temperature (T2 ≤ T) equal to or greater than the second predetermined temperature T2. The lower the temperature T of the head 20, the easier it is for airflow to occur. In a condition where the amount of ink adhesion on the ejection surface 23 tends to increase due to such airflow, the coefficient k is determined to be small. As a result, the threshold value h (= h0 × k) becomes small.

[0047] The dimension G of the gap is divided into a small gap (G < G1) less than the first predetermined dimension G1, a medium gap (G1 ≤ G < G2) equal to or greater than the first predetermined dimension G1 and less than the second predetermined dimension G2, and a large gap (G2 ≤ G) equal to or greater than the second predetermined dimension G2. The larger the dimension G of the gap, the larger the amount of ink mist floating. Under the condition that the amount of ink adhering to the ejection surface 23 tends to increase due to such an air flow, the coefficient k is set small. As a result, the threshold value h (= h0 × k) becomes small.

[0048] <Calculation process> The control device 50 executes a calculation process for calculating a reference value of the partial region P based on the partial image data. As shown in FIG. 5, this partial region P has a plurality of scan regions S, and the scan region S is smaller than the partial region P. The partial region P is a rectangular region having a dimension P1 in the front-rear direction and a dimension P2 in the left-right direction. The scan region S is a region within the partial region P and is a rectangular region having a dimension S1 in the front-rear direction and a dimension S2 in the left-right direction. The dimension S1 is smaller than the dimension P1, and the dimension S2 is smaller than the dimension P2. The dimension P1 is equal to the dimension E (FIG. 1) of the nozzle row in the front-rear direction.

[0049] The control device 50 acquires partial image data, which is image data corresponding to the partial region P of the printing medium A, from the image data, and acquires scan image data corresponding to the scan region S from the partial image data. This image data has the positions and sizes of the dots forming the image to be printed. The control device 50 calculates the printing duty in the scan region S from the number and size of the dots formed in the scan region S based on the scan image data.

[0050] The printing duty is the ratio (c / b) of the area c of the image formed in the scan area S to the area b of the scan area S. The area b of this scan area S is predetermined, and the area c of the image of the scan area S is obtained based on the number and size of the dots constituting the image of the scan area S. For example, the size of the dot corresponds to the amount of ink droplets forming the dot, and there are no dots with an ink droplet amount of 0, small dots with an ink droplet amount less than a predetermined range, medium dots with an ink droplet amount within a predetermined range, and large dots with an ink droplet amount larger than the predetermined range.

[0051] The larger the number of dots constituting the image of the scan area S and the larger the size of the dots, the larger the area c of the image of the scan area S and the larger the printing duty (c / b). For example, when all the dots constituting the image of the scan area S are large dots, the area c of the image of the scan area S is equal to the area b of the scan area S, and the printing duty is 100%. On the other hand, when all the dots constituting the image of the scan area S are dots with no ink droplets, the area c of the image of the scan area S is 0, and the printing duty is 0%.

[0052] In the calculation process, the control device 50 alternately repeats the arithmetic operation of calculating the printing duty of the scan area S and the displacement operation of displacing the scan area S by predetermined dimensions D1 and D2 in the partial area P. In the example of FIG. 5, the control device 50 performs an arithmetic operation on the scan area S arranged at the left rear corner of the partial area P, and then performs a displacement operation of displacing the scan area S forward by a predetermined dimension D1. Then, the control device 50 alternately executes the arithmetic operation on the scan area S at the displacement position and the displacement operation of displacing the scan area S forward by a predetermined dimension D1.

[0053] When the scan area S reaches the left front corner in the partial area P, the control device 50 displaces the scan area S to the right by a predetermined dimension D2 and performs an arithmetic operation on the scan area S at this displaced position. Then, the control device 50 alternately executes a displacement operation of the scan area S by a predetermined dimension D1 to the rear and an arithmetic operation on the scan area S at the displaced position.

[0054] This predetermined dimension D1 is greater than 0 and not more than the dimension S1 of the scan area S, and the predetermined dimension D2 is greater than 0 and not more than the dimension S2 of the scan area S. In this way, the control device 50 calculates the printing duty of the scan area S at the displaced position while displacing the scan area S by the predetermined dimensions D1 and D2 in the partial area P. Thereby, in the partial area P, the printing duty of one or a plurality of scan areas S in the partial area P is obtained.

[0055] <Control Method of Printing Device> The printing device 10 is controlled by the control device 50, for example, in accordance with the flowchart of an example of the control method shown in FIG. 6. First, the control device 50 acquires the image data to be printed from the storage unit 52 or the communication interface 53 (step S10).

[0056] Also, the control device 50 executes a gap acquisition process regarding the path operation of the current recording process in the printing process (step S11). In this gap acquisition process, the control device 50 acquires the dimension G of the gap between the partial area P targeted for the path operation of the current recording process of the print medium A and the ejection surface 23 based on the detection signal of the distance measurement sensor 14.

[0057] Also, the control device 50 executes a temperature acquisition process for acquiring temperature information of the head 20 based on the detected temperature by the temperature sensor 13 (step S12). Here, for example, the control device 50 acquires the temperature of the head 20 detected by the temperature sensor 13 as the temperature information.

[0058] Then, the control device 50 executes a threshold value acquisition process for acquiring a threshold value based on the dimension G of the gap and the temperature of the head 20 (step S13). For example, the control device 50 refers to the list in the example of FIG. 4, acquires a coefficient k corresponding to the dimension G of the gap and the temperature of the head 20, and acquires the product of this coefficient k and a predetermined value h0 as the threshold value h. Here, the larger the dimension G of the gap, the larger the amount of ink mist that floats without reaching the printing medium A. Also, the lower the temperature of the head 20, the faster the ink ejection speed, and the easier it is for an air flow to be generated by the ink ejection. Under the condition that the amount of ink adhesion on the ejection surface 23 is likely to increase due to such an air flow, the coefficient k is small, and the threshold value h based on the coefficient k becomes low.

[0059] Also, the control device 50 acquires partial image data that is the target of the path operation in the current recording process from the image data of the printing process, and executes a calculation process for calculating a reference value of the partial region P based on the partial image data (step S14). Here, the control device 50 acquires the scan image data that is the target of the calculation process from the partial image data, and calculates the printing duty of the scan region S as the reference value based on the scan image data.

[0060] Then, the control device 50 executes a duty determination process to determine whether the printing duty of the scan region S is equal to or greater than the threshold value h (step S15). Here, if the printing duty of the scan region S is less than the threshold value h (step S15: NO), the control device 50 determines whether the duty determination process of S15 has been executed for all the scan regions S in the partial region P (step S16). If there remains a scan region S for which the duty determination process has not been executed (step S16: NO), the control device 50 returns to the process of step S14 and executes the subsequent processes. Thereby, the control device 50 calculates the printing duty of the next scan region S in the partial region P and determines whether the printing duty is equal to or greater than the threshold value h.

[0061] In step S16, when the control device 50 has executed the duty determination process for all the scan areas S in the partial area P (step S16: YES), the print duty of all the scan areas S in the partial area P is less than the threshold value h (step S15: NO). Therefore, the control device 50 determines that the method of the current recording process is the single-pass method (step S17). Thereby, the control device 50, for example, turns on the single-pass method flag in the storage unit 52 or reads out the program of the single-pass method recording process from the storage unit 52.

[0062] As described above, when the print duty is small over the entire area of the partial area P, the number of ink ejection times per unit time in the current recording process is small, and it is a condition where it is difficult for the amount of ink adhering to the ejection surface 23 to increase due to the air flow. Therefore, the number of pass operations can be reduced by the single-pass method recording process, and the lengthening of the printing time can be reduced.

[0063] In step S15, when the print duty of the scan area S is equal to or greater than the threshold value h (step S15: YES), the control device 50 determines that the method of the current recording process is the multi-pass method (step S18). Thereby, the control device 50, for example, turns on the multi-pass method flag in the storage unit 52 or reads out the program of the multi-pass method recording process from the storage unit 52.

[0064] As described above, when the print duty of at least one scan area S in the partial area P is equal to or greater than the threshold value h, there is a part where the number of ink ejection times per unit time is large in the current recording process. In such a condition where the amount of ink adhering to the ejection surface 23 is likely to increase due to the air flow, the number of ink ejection times per unit time is reduced by the multi-pass method recording process. Thereby, the floating amount of mist and the air flow rate can be reduced, the amount of ink mist adhering to the head 20 due to the air flow can be decreased, and the ink ejection failure caused by the adhering ink on the ejection surface 23 can be suppressed.

[0065] Then, the control device 50 executes the recording process in the method determined in step S17 or S18 (step S19). Here, in the recording process of the single-pass method, the control device 50 executes a conveyance operation after executing one pass operation based on the partial image data. By this pass operation, a partial image based on the partial image data is formed in the partial region P facing the ejection surface 23.

[0066] Also, in the recording process of the multi-pass method, the control device 50 divides the partial image data into the same number of pass partial image data as the number of pass operations. Then, the control device 50 executes a plurality of pass operations based on the pass partial image data and then executes a conveyance operation. By these plurality of pass operations, pass partial images based on the pass partial image data are laminated in the partial region P, and a partial image based on the partial image data is formed by the laminated plurality of pass partial images.

[0067] Then, the control device 50 determines whether or not all the recording processes in the printing process have been executed (step S20). If there are remaining recording processes that have not been executed (step S20: NO), the control device 50 returns to the process of step S11 and executes the subsequent processes. On the other hand, if all the recording processes have been executed (step S20: YES), the control device 50 ends the process.

[0068] <Modification Example 1> In the printing apparatus 10 according to the above-described Embodiment 1, the control device 50 determines the method of the recording process based on the determination result of the duty determination process. In contrast, in the printing apparatus 10 according to Modification Example 1, the control device 50 determines the method of the recording process based on the determination result of the region determination process.

[0069] The printing apparatus 10 according to Modification Example 1 is controlled by the control device 50, for example, in accordance with a flowchart of an example of the control method shown in FIG. 7. In the flowchart of FIG. 7, the processes of S30 and S31 are executed between S15, S16, and S18 of FIG. 6, and the process of S32 is executed between S19 and S20 of FIG. 6.

[0070] Specifically, the control device 50 acquires the image data to be printed (step S10), and acquires the dimension G of the gap between the partial region P, which is the target of the path operation in the current recording process, and the ejection surface 23 (step S11). Further, the control device 50 acquires the temperature of the head 20 as temperature information (step S12), and acquires a threshold value h based on the dimension G of the gap and the temperature of the head 20 (step S13). Further, the control device 50 calculates the print duty of the scan region S as a reference value for the partial region P based on the data that is the target of the path operation in the current recording process (step S14).

[0071] Then, the control device 50 executes a duty determination process to determine whether or not the print duty of the scan region S is equal to or greater than the threshold value h (step S15). Here, when the print duty of the scan region S is equal to or greater than the threshold value h (step S15: YES), the control device 50 performs an increment of adding 1 to the number (number of regions N) of scan regions S in which the print duty is equal to or greater than the threshold value h in the partial region P (step S30), and proceeds to the process of step S31. On the other hand, if the print duty of the scan region S is less than the threshold value h (step S15: NO), the control device 50 skips the process of step S30 and proceeds to the process of step S31.

[0072] In step S31, the control device 50 executes a region determination process to determine whether or not the number of regions N is equal to or greater than a predetermined number. Here, when the number of regions N is less than the predetermined number (step S31: NO), the control device 50 determines whether or not the duty determination process of S15 has been executed for all the scan regions S in the partial region P (step S16). When there remains a scan region S for which the duty determination process has not been executed (step S16: NO), the control device 50 returns to the process of step S14 and executes the subsequent processes. As a result, the print duty of the next scan region S in the partial region P is calculated, and the duty determination process is executed for that print duty.

[0073] Then, when the control device 50 executes the duty determination process for all the scan areas S in the partial area P (step S16: YES), it determines that the method of the current recording process is the single-pass method (step S17). When the number of scan areas S (number of areas N) with a print duty equal to or higher than the threshold among all the scan areas S in the partial area P is less than a predetermined number (step S31: NO), it is a condition where it is difficult for the amount of ink adhering to the ejection surface 23 to increase due to the airflow. Therefore, it is possible to reduce the number of pass operations in the recording process of the single-pass method and reduce the lengthening of the printing time.

[0074] In step S31, when the number of areas N is equal to or greater than the predetermined number (step S31: YES), the control device 50 determines that the method of the current recording process is the multi-pass method (step S18). Thus, when the print duty of at least N scan areas S in the partial area P is equal to or higher than the threshold, it is a condition where it is easy for the amount of ink adhering to the ejection surface 23 to increase due to the airflow. Therefore, by reducing the number of ink ejection times per unit time by the recording process of the multi-pass method, it is possible to suppress ink ejection failures caused by the adhering ink on the ejection surface 23.

[0075] Then, the control device 50 executes the recording process in the method determined in step S17 or S18 (step S19) and also resets the number of areas N to 0 (step S32). Then, the control device 50 determines whether or not it has executed all the recording processes in the printing process (step S20). If there is an unexecuted recording process (step S20: NO), the control device 50 returns to the process of step S11 and executes the subsequent processes. On the other hand, if all the recording processes have been executed (step S20: YES), the control device 50 ends the process.

[0076] (Embodiment 2) As shown in FIG. 1, the printing apparatus 10 according to Embodiment 2 of the present disclosure further includes a maintenance unit 60 that maintains the nozzles 21. The maintenance unit 60 is disposed, for example, in a maintenance area to the right of the printing area where the platen 11 is disposed. The moving device 30 is capable of moving the head 20 by the carriage 31 across the printing area and the maintenance area.

[0077] The maintenance unit 60 includes a wiper 61 that wipes the ejection surface 23 and a first displacement device 62 that displaces the wiper 61. The wiper 61 is, for example, flat and has a dimension longer than the dimension E of the nozzle row of the head 20 along the front-rear direction, and is disposed at a position overlapping the nozzle row when viewed from the right. Further, the wiper 61 is disposed below the ejection surface 23 of the head 20 in the vertical direction.

[0078] The first displacement device 62 has a first displacement motor 63 (FIG. 2), and displaces the wiper 61 between a contact position where the wiper 61 contacts the ejection surface 23 and a separation position where the wiper 61 is separated from the ejection surface 23 by driving the first displacement motor 63. For example, in the maintenance process, the first displacement device 62 raises the wiper 61 from the separation position to the contact position, and in the printing process, the first displacement device 62 lowers the wiper 61 from the contact position to the separation position.

[0079] As shown in FIG. 2, the first displacement motor 63 of the first displacement device 62 is electrically connected to the first displacement drive circuit 57, and the first displacement drive circuit 57 is electrically connected to the control device 50. The control device 50 generates a control signal for driving the first displacement motor 63, and the first displacement drive circuit 57 generates a drive signal based on this control signal. Then, the first displacement motor 63 drives based on the drive signal so as to displace the wiper 61 between the contact position and the separation position by the first displacement device 62 and stop the wiper 61 at these positions.

[0080] <Maintenance Process> When a wiping process is used as a maintenance process, the control device 50 moves the head 20 on the wiper 61 by the carriage 31 with the wiper 61 disposed at the contact position by the first displacement device 62. As a result, the ejection surface 23 of the head 20 moves left or right with respect to the wiper 61 while being in contact with the wiper 61. For this reason, the ink on the ejection surface 23 is removed by the wiper 61, and it is possible to suppress the contamination of the printed medium A caused by the ink on the ejection surface 23 and the poor ejection of ink from the nozzles 21 of the ejection surface 23.

[0081] <Control Method of Printing Device> The printing device 10 according to the second embodiment is controlled by the control device 50, for example, in accordance with a flowchart of an example of the control method shown in FIG. 8. In the flowchart of FIG. 8, S17 in FIG. 6 is not executed, the process of S42 is executed instead of S18 in FIG. 6, the processes of S40 and S41 are executed between S15 and S16 and between S42, and the processes of S43 to S45 are executed between S19 and S20.

[0082] Specifically, the control device 50 acquires the image data of the object of the printing process (step S10), and acquires the dimension G of the gap between the partial region P that is the object of the path operation in the current recording process and the ejection surface 23 (step S11). Further, the control device 50 acquires the temperature of the head 20 as temperature information (step S12), and acquires a threshold value h based on the dimension G of the gap and the temperature of the head 20 (step S13). Further, the control device 50 calculates the print duty of the scan region S as a reference value of the partial region P based on the partial image data that is the object of the path operation in the current recording process (step S14).

[0083] Then, the control device 50 executes duty determination processing to determine whether the print duty of the scan area S is equal to or greater than the threshold value h (step S15). Here, when the print duty of the scan area S is equal to or greater than the threshold value h (step S15: YES), the control device 50 increments the number (area number N) of scan areas S in the partial area P where the print duty is equal to or greater than the threshold value by 1 (step S40), and proceeds to the processing of step S41. On the other hand, if the print duty of the scan area S is less than the threshold value h (step S15: NO), the control device 50 skips the processing of step S40 and proceeds to the processing of step S41.

[0084] In step S41, the control device 50 executes area determination processing to determine whether the area number N is equal to or greater than a predetermined number. Here, when the area number N is less than the predetermined number (step S41: NO), the control device 50 determines whether the duty determination processing of S15 has been executed for all the scan areas S in the partial area P (step S16). If there remains a scan area S for which the duty determination processing has not been executed (step S16: NO), the control device 50 returns to the processing of step S14 and executes the subsequent processing. Thereby, the print duty of the next scan area S in the partial area P is calculated, and the duty determination processing is executed for that print duty.

[0085] Then, when the control device 50 has executed the duty determination processing for all the scan areas S in the partial area P (step S16: YES), the control device 50 skips the processing of step S42 and proceeds to the processing of step S19.

[0086] In step S41, when the area number N is equal to or greater than the predetermined number (step S41: YES), the control device 50, for example, turns on the reservation flag for the maintenance processing in the storage unit 52 and reserves the maintenance processing (step S42). Then, the control device 50 executes the recording process (step S19). The method of this recording process is predetermined as a single-pass method or a multi-pass method, and the recording process is executed in this predetermined method.

[0087] Subsequently, the control device 50 determines whether maintenance processing is reserved (step S43). Here, when the reservation flag in the storage unit 52 is on, since maintenance processing is reserved in the processing of step S42 (step S43: YES), the control device 50 executes the maintenance processing (step S44). Then, the control device 50 resets the reservation flag to off and also resets the number of areas N to 0 (step S45). In this way, for each recording process, based on the reference value, the dimension G of the gap, and the temperature information, maintenance processing for maintaining the nozzle 21 by the maintenance unit 60 after the execution of the path operation of the recording process is executed.

[0088] When this maintenance processing is reserved, that is, when the number of areas N is equal to or more than a predetermined number, it is a condition in which the amount of ink adhering to the ejection surface 23 tends to increase due to the air flow. Therefore, as the maintenance processing, for example, wiping of the ejection surface 23 by the wiper 61 is executed, so that the ink on the ejection surface 23 is removed by the wiper 61, and thus it is possible to suppress ink ejection failure caused by the adhering ink on the ejection surface 23.

[0089] On the other hand, when the reservation process of the maintenance process in step S42 is skipped, since the maintenance process is not reserved (step S43: NO), the process of step S44 is skipped and the number of areas N is reset to 0 (step S45). In this way, when the number of areas N is less than a predetermined number, it is a condition in which the amount of ink adhering to the ejection surface 23 hardly increases due to the air flow. Therefore, by not executing the maintenance process, it is possible to reduce the extension of the printing time.

[0090] Then, the control device 50 determines whether all the recording steps in the printing process have been executed (step S20). If there is an unexecuted recording step (step S20: NO), the control device 50 returns to the process of step S11 and executes the subsequent processes. On the other hand, if all the recording steps have been executed (step S20: YES), the control device 50 ends the process.

[0091] (Embodiment 3) As shown in FIGS. 1 and 2, the printing apparatus 10 according to Embodiment 3 of the present disclosure further includes a maintenance unit 60 that maintains the nozzles 21. The maintenance unit 60 has, for example, a wiper 61 that wipes the ejection surface 23, a first displacement device 62 that displaces the wiper 61, a cap 64, a suction pump 65, and a second displacement device 66. The cap 64, the suction pump 65, and the second displacement device 66 are arranged in a maintenance area to the left of the printing area. The wiper 61 and the first displacement device 62 are arranged in a maintenance area to the right of the printing area. In this case, the moving device 30 can move the head 20 by the carriage 31 across the left maintenance area, the printing area, and the right maintenance area.

[0092] The cap 64 has, for example, a box shape with an open upper surface and covers the ejection surface 23 of the head 20. The second displacement device 66 has a second displacement motor 67, and drives the second displacement motor 67 to displace the cap 64 between a contact position where the cap 64 contacts the ejection surface 23 and a separation position where the cap 64 is separated from the ejection surface 23. For example, in the maintenance process, the second displacement device 66 raises the cap 64 from the separation position to the contact position, and in the printing process, the second displacement device 66 lowers the cap 64 from the contact position to the separation position.

[0093] The second displacement motor 67 of the second displacement device 66 is electrically connected to the second displacement drive circuit 58, and the second displacement drive circuit 58 is electrically connected to the control device 50. The control device 50 generates a control signal for driving the second displacement motor 67, and the second displacement drive circuit 58 generates a drive signal based on this control signal. Then, the second displacement motor 67 drives based on the drive signal so as to displace the cap 64 between the contact position and the separated position by the second displacement device 66 and stop the cap 64 at these positions.

[0094] <Maintenance process> When a wiping process is executed as a maintenance process, the control device 50 moves the head 20 on the wiper 61 by the carriage 31 with the wiper 61 arranged at the contact position by the first displacement device 62. As a result, the ejection surface 23 of the head 20 moves left or right with respect to the wiper 61 while being in contact with the wiper 61. For this reason, the ink on the ejection surface 23 is removed by the wiper 61.

[0095] Also, when a purge process is executed as a maintenance process, the control device 50 arranges the cap 64 at the contact position by the second displacement device 66. As a result, the cap 64 comes into contact with the ejection surface 23 of the head 20, and the space surrounded by this cap 64 and the ejection surface 23 is sucked by the suction pump 65. Thereby, ink is sucked from the nozzle 21 that opens to the ejection surface 23, the ink is ejected from the nozzle 21, and is discharged to the cap 64. By this purge process, foreign matters such as bubbles and thickened ink in the head 20 are discharged, and it is possible to suppress poor ejection of ink from the nozzle 21 due to the foreign matters.

[0096] <Control method of printing device> The printing apparatus 10 according to Embodiment 3 is controlled by the control device 50, for example, in accordance with a flowchart of an example of the control method shown in FIGS. 9 and 10. In the flowcharts of FIGS. 9 and 10, S17 in FIG. 6 is not executed, the process of S50 is executed instead of S13 in FIG. 6, the processes of S51 to S56 are executed instead of S15 in FIG. 6, the processes of S57 to S58 are executed instead of S18 in FIG. 6, and the processes of S59 to S61 are executed between S19 and S20.

[0097] Specifically, the control device 50 acquires the image data of the object of the printing process (step S10). Further, the control device 50 acquires the dimension G of the gap between the partial region P that is the object of the path operation in the current recording process and the ejection surface 23 (step S11), and also acquires the temperature of the head 20 as temperature information (step S12).

[0098] Then, the control device 50 executes a threshold value acquisition process, and acquires a first threshold value and a second threshold value larger than the first threshold value based on the dimension G of the gap and the temperature of the head 20 (step S50). For example, when the first threshold value is represented by the product of a first predetermined value and a coefficient k, and the second threshold value is represented by the product of a second predetermined value and the coefficient k, the second predetermined value is larger than the first predetermined value. Further, the coefficient k is acquired based on the list shown in the example of FIG. 4. According to this list, the lower the temperature T of the head 20 and the larger the dimension G of the gap, the more likely the amount of ink adhesion on the ejection surface 23 due to the air flow is, and the smaller the coefficient k is. Therefore, the first threshold value and the second threshold value based on the coefficient k become smaller.

[0099] Also, the control device 50 calculates the printing duty of the scan region S as a reference value of the partial region P based on the partial image data that is the object of the path operation in the current recording process (step S14). Then, the control device 50 executes a duty determination process and determines whether the printing duty of the scan region S is equal to or greater than the first threshold value (step S51). Here, if the printing duty of the scan region S is less than the first threshold value (step S51: NO), the control device 50 proceeds to the process of step S16.

[0100] On the other hand, when the printing duty of the scan area S is equal to or greater than the first threshold value (step S51: YES), the control device 50 performs an increment operation of adding 1 to the number (first area number Na) of scan areas S in the partial area P where the printing duty is equal to or greater than the first threshold value (step S52). Then, the control device 50 executes an area determination process for determining whether the first area number Na is equal to or greater than a first predetermined number (step S53). Here, when the first area number Na is less than the first predetermined number (step S53: NO), the control device 50 proceeds to the process of step S16.

[0101] On the other hand, when the first area number Na is equal to or greater than the first predetermined number (step S53: NO), the control device 50 executes a duty determination process and determines whether the printing duty of the scan area S is equal to or greater than a second threshold value (step S54). Here, if the printing duty of the scan area S is less than the second threshold value (step S54: NO), the control device 50 proceeds to the process of step S16.

[0102] In step S16, the control device 50 determines whether the duty determination process of S51 has been executed for all scan areas S in the partial area P (step S16). If there remains a scan area S for which the duty determination process has not been executed (step S16: NO), the control device 50 returns to the process of step S14 and executes the subsequent processes. Then, when the duty determination process of S51 has been executed for all scan areas S in the partial area P (step S16: YES), the control device 50 proceeds to the process of step S19.

[0103] Also, in the process of step S54, when the printing duty of the scan area S is equal to or greater than the second threshold value (step S54: YES), the control device 50 performs an increment operation of adding 1 to the number (second area number Nb) of scan areas S in the partial area P where the printing duty is equal to or greater than the second threshold value (step S55). Then, the control device 50 executes an area determination process for determining whether the second area number Nb is equal to or greater than a second predetermined number (step S56).

[0104] Here, when the number Nb of second regions is less than a second predetermined number (step S56: NO), the control device 50, for example, turns on a reservation flag for a wiping process of a maintenance process in the storage unit 52, reserves the wiping process as a maintenance process (step S57), and proceeds to the process of step S19. On the other hand, when the number Nb of second regions is greater than or equal to the second predetermined number (step S56: YES), the control device 50, for example, turns on a reservation flag for a purge process of a maintenance process in the storage unit 52, reserves the purge process as a maintenance process (step S58), and proceeds to the process of step S19.

[0105] In the process of step S19, the control device 50 executes a recording process in a predetermined method. Subsequently, the control device 50 determines whether a maintenance process is reserved (step S59). Here, when the reservation flag for the wiping process is on, since the wiping process is reserved as a maintenance process in the process of step S57 (step S59: YES), the control device 50 executes the wiping process (step S60).

[0106] Also, when the reservation flag for the purge process is on, since the purge process is reserved as a maintenance process in the process of step S58 (step S59: YES), the control device 50 executes the purge process (step S60). Then, the control device 50 resets the reservation flag to off and also resets the number Na of first regions and the number Nb of second regions to 0 (step S61). In this way, for each recording process, based on the reference value, the dimension G of the gap, and the temperature information, the purge process or the wiping process is executed as a maintenance process to be executed after the execution of the pass operation.

[0107] When this maintenance process is reserved, that is, when the number Na of first regions is greater than or equal to a first predetermined number, it is a condition in which the amount of ink adhesion on the ejection surface 23 tends to increase due to the airflow. Therefore, by executing the maintenance process of the nozzle 21, it is possible to suppress ink ejection failure caused by the adhered ink on the ejection surface 23.

[0108] Here, when the number Nb of the second regions is equal to or greater than a second predetermined number, ink is more likely to adhere to the ejection surface 23 by the airflow than when the number Nb of the second regions is less than the second predetermined number. In such a case, in order to eject ink from the nozzles 21 that open to the ejection surface 23 by purge processing, it is possible to more reliably suppress ejection failure of the ink.

[0109] Furthermore, when the number Na of the first regions is equal to or greater than a first predetermined number and the number Nb of the second regions is less than the second predetermined number, ejection failure of the ink is less likely to occur than when the number Nb of the second regions is equal to or greater than the second predetermined number. In such a case, by wiping processing for removing the ink on the ejection surface 23 by the wiper 61, it is possible to suppress ejection failure of the ink caused by the adhered ink on the ejection surface 23 while suppressing ink consumption more than purge processing.

[0110] Also, in the process of step S59, when the reservation flag for maintenance processing is off, since maintenance processing is not reserved in step S57 or S58 (step S59: NO), the control device 50 skips the process of step S60. Then, the control device 50 resets the number Na of the first regions and the number Nb of the second regions to 0 (step S61).

[0111] In this way, when maintenance processing is not reserved, that is, when the number Na of the first regions is less than the first predetermined number, it is a condition in which the amount of ink adhering to the ejection surface 23 due to the airflow is less likely to increase. Therefore, by not executing the maintenance processing, it is possible to reduce the extension of the printing time.

[0112] Then, the control device 50 determines whether or not all the recording steps in the printing process have been executed (step S20). If there is an unexecuted recording step (step S20: NO), the control device 50 returns to the process of step S11 and executes the subsequent processes. On the other hand, if all the recording steps have been executed (step S20: YES), the control device 50 ends the process.

[0113] <Modification Example 2>

[0114]

[0115]

[0116] Further, for example, a method of discharging ink from the nozzles 21 according to the temperature of the head 20 may be used for the temperature information of the head 20. In this case, the lower the detected temperature of the temperature sensor 13, the lower the temperature of the head 20, and since the temperature of the ink in the head 20 is also low, the viscosity of the ink in the head 20 increases. Further, since the viscosity of the ink is high, it is predetermined that the voltage of the drive signal of the drive element 22 increases. When the voltage of the drive signal of the drive element 22 increases, the discharge speed of the ink increases, so that an air flow is likely to be generated between the discharge surface 23 and the printing medium A. Mist is generated with the discharge of the ink between the discharge surface 23 and the printing medium A, and the mist is floating. For this reason, the mist is diffused by the air flow and causes contamination inside the printing apparatus 10. Therefore, in order to suppress the diffusion of the mist by the air flow, when the detected temperature of the temperature sensor 13 is less than a predetermined temperature, the waveform of the drive signal of the drive element 22 is predetermined so that a plurality of ink droplets coalesce during flight from the nozzles 21 until they land on the printing medium A. On the other hand, when the detected temperature of the temperature sensor 13 is equal to or higher than a predetermined temperature, the waveform of the drive signal of the drive element 22 is predetermined so that a single ink droplet is discharged from the nozzles 21.

[0117] In this way, the detected temperature of the temperature sensor 13 and the waveform of the drive signal of the drive element 22 are pre-associated. The temperature of the head 20 correlates with the detected temperature of the temperature sensor 13, and the ink discharge method (for example, the discharge method of flying and coalescing droplets, the discharge method of single droplets) correlates with the waveform of the drive signal. Therefore, the control device 50 can acquire the ink discharge method, for example, the waveform of the drive signal of the drive element 22, as the temperature information of the head 20.

[0118] <Other Modification Examples> In the flowcharts of FIGS. 6 to 10, when there are remaining recording steps that the control device 50 has not executed in all the recording steps in the printing process (step S20: NO), the process returns to the process of step S11, and the subsequent processes are executed. For this reason, the control device 50 executes the gap acquisition process of step S11 for each recording step. However, for example, the unevenness of the printing medium A is absent or small, and there may be a case where the difference in the dimension G of the gap in all the recording steps is smaller than a predetermined dimension. In such a case, in all the above embodiments and modifications, the control device 50 may skip the gap acquisition process of step S11 for the second and subsequent recording steps, and use the dimension G of the gap acquired in the first gap acquisition process as the dimension G of the gap for the second and subsequent recording steps.

[0119] Also, in the flowcharts of FIGS. 6 to 10, the control device 50 executes the temperature acquisition process of step S12 for each recording step in the same manner as the gap acquisition process of step S11. However, for example, there may be a case where the difference in the detected temperature of the temperature sensor 13 in all the recording steps is smaller than a predetermined dimension. In such a case, in all the above embodiments and modifications, the control device 50 may skip the temperature acquisition process of step S12 for the second and subsequent recording steps, and use the temperature information acquired in the first temperature acquisition process as the temperature information for the second and subsequent recording steps.

[0120] In this way, the gap acquisition process of step S11 and the temperature acquisition process of step S12 for the second and subsequent recording steps may be skipped. In this case, the threshold acquisition processes of steps S13 and S50 for acquiring the thresholds based on the dimension G of these gaps and the temperature information may be skipped in the second and subsequent recording steps. Then, the control device 50 may use the threshold acquired in the first recording step in the threshold acquisition process in the second and subsequent recording steps.

[0121] In Embodiments 1 to 3, the printing apparatus 10 uses the distance measuring sensor 14 to acquire the dimension G of the gap between the ejection surface 23 and the printing medium A. However, the acquisition of the dimension G of the gap is not limited to this. The printing apparatus 10 may have a platen 11 that can move up and down, and acquire the dimension G of the gap based on the position of this platen 11. In this case, the printing apparatus 10 indicates a numerical value corresponding to the vertical position of the platen 11. For example, the printing apparatus 10 may display the numerical value on a display, or there may be several numbers written on a part of the platen that can move up and down, but the user may be made to recognize the numerical value by physically hiding other numerical values so that only the numerical value corresponding to the vertical position can be seen. Then, when the user inputs the numerical value via the input device 12, the control device 50 may acquire the dimension G of the gap between the ejection surface 23 and the printing medium A based on the distance between the ejection surface 23 and the platen that can move up and down.

[0122] In Embodiments 1 to 3, the temperature sensor 13 detects the temperature of the head 20 and outputs the detected temperature to the control device 50. However, this is not limited to this. The temperature sensor 13 may detect the current of the temperature sensor 13 and output the detected current value to the control device 50. The control device 50 may acquire the temperature of the head 20 based on this current value. Further, the temperature sensor 13 may detect the resistance value of the temperature sensor 13 and output the detected resistance value to the control device 50. The control device 50 may acquire the temperature of the head 20 based on the resistance value of the temperature sensor 13.

[0123] In Embodiment 2, for each recording process, a maintenance process for maintaining the nozzle 21 by the maintenance unit 60 after the execution of the pass operation of the recording process is executed based on the reference value, the dimension G of the gap, and the temperature information. However, this is not limited to this. A maintenance process for maintaining the nozzle 21 by the maintenance unit 60 after the execution of the pass operation of the recording process may be executed based on the reference value, the dimension G of the gap, and the temperature information for every plurality of (for example, two) recording processes.

[0124] In Embodiment 3, for each recording process, a purge process or a wiping process was executed as maintenance processing to be executed after the execution of the pass operation based on the reference value, the dimension G of the gap, and the temperature information, but the present invention is not limited thereto. For each of a plurality of times (for example, two times) of recording processes, a purge process or a wiping process may be executed as maintenance processing to be executed after the execution of the pass operation based on the reference value, the dimension G of the gap, and the temperature information.

[0125] In Embodiment 1, in step S17, the control device 50 turned on the flag of the single-pass method in the storage unit 52 or read out the program of the recording process of the single-pass method from the storage unit 52. For example, when the control device 50 turns on the flag of the single-pass method in the storage unit 52 and the image data acquired in step S10 has been subjected to halftone processing, the image data can be used for printing as it is. Further, when the control device 50 turns on the flag of the single-pass method in the storage unit 52 and the image data acquired in step S10 has not been subjected to halftone processing, after performing halftone processing on the print image, a range equivalent to the image data acquired in step S10 may be reacquired. When reacquiring, the control device 50 may perform halftone processing on the image data, or may cause an external device to perform halftone processing on the image data. Note that the program of the recording process of the single-pass method may be a program that divides the print image into a range equivalent to the image data acquired in step S10 after performing halftone processing on the print image.

[0126] In Embodiment 1, the control device 50 turns on the multi-pass method flag in the storage unit 52 or reads out the program of the multi-pass method recording process from the storage unit 52 in step S18. When the control device 50 turns on the multi-pass method flag in the storage unit 52 and the image data acquired in step S10 has been halftone processed, the control device 50 masks the partial image data of the recording process shown in FIG. 11 and divides the partial image data into, for example, first-pass partial image data representing a first-pass partial image and second-pass partial image data representing a second-pass partial image. Further, when the control device 50 turns on the multi-pass method flag in the storage unit 52 and the image data acquired in step S10 has not been halftone processed, the control device 50 may halftone process the image data or may re-acquire from an external device the image data that has been halftone processed by the external device. Further, the process of dividing the partial image data into a plurality of pass partial image data may be performed by the control device 50 or may be performed by an external device.

[0127] For example, when the multi-pass method flag is turned on for all partial images constituting a print image, the control device 50 causes the external device to halftone process the image data. After halftone processing, the external device attaches a mask with an application rate of less than 50% and decreasing toward the front to the first 70 pixels in the front part of the plurality of pass partial image data, attaches a mask with an application rate of less than 50% and increasing toward the rear to the last 70 pixels in the rear part, and attaches a mask with an application rate of 50% to the 70 pixels in the central part between the front part and the rear part, and divides the partial image data into a plurality of pass partial image data. The control device 50 re-acquires the plurality of such pass partial image data from the external device and executes print processing based on the pass partial image data.

[0128] In this printing process, the control device 50 prints the path partial image on the printing medium A by a path operation based on the path partial image data, and conveys the printing medium A by 70 pixels. Then, the control device 50 prints the next path partial image on the printing medium A and conveys the printing medium A by 70 pixels. These operations are repeated. That is, a block of 70 pixels in the partial image is printed in three path operations. For example, 17 pixels out of a block of 70 pixels are printed in the first path operation, 35 pixels out of a block of 70 pixels are printed in the second path operation, and 18 pixels out of a block of 70 pixels are printed in the third path operation, completing the printing of a block of 70 pixels in the partial image. Note that the program for the multi-pass recording process may be a program that masks the partial image data of the recording process shown in FIG. 11 and divides the partial image data into first path partial image data representing the first path partial image and second path partial image data representing the second path partial image.

[0129] In addition, unless the above-described all embodiments exclude each other, they may be combined with each other. Also, from the above description, many improvements and other embodiments of the present disclosure will be apparent to those skilled in the art. Therefore, the above description should be construed as illustrative only and provided for the purpose of teaching those skilled in the art the best mode of carrying out the present disclosure. Without departing from the spirit of the present disclosure, the details of its structure and / or function can be substantially changed.

Explanation of Reference Numerals

[0130] 10: Printing device 13: Temperature sensor 20: Head 21: Nozzle 23: Ejection surface 30: Moving device 40: Conveying device 50: Control device 60: Maintenance unit 61: Wiper

Claims

1. A plurality of nozzles for discharging ink onto a printing medium, a head having a discharge surface through which the plurality of nozzles open, a moving device for moving the head, a conveying device for conveying the printing medium in a direction intersecting the moving direction of the head, a temperature sensor for detecting temperature, and a control device, wherein the control device performs a printing process including a recording process that includes a pass operation of discharging ink from the nozzles to a partial area of the printing medium while moving the head based on image data, and a conveying operation of conveying the printing medium, a gap acquisition process of acquiring a dimension of a gap between the printing medium and the discharge surface, a temperature acquisition process of acquiring temperature information of the head based on a detected temperature by the temperature sensor, for each of the recording processes, a method determination process of determining, based on a reference value, the dimension of the gap, and the temperature information, whether the method of the recording process is a single-pass method of performing the pass operation on one partial area of the printing medium or a multi-pass method of complementarily performing a plurality of pass operations on one partial area of the printing medium and having a smaller number of ink discharges per unit time than the single-pass method, a calculation process of calculating the reference value of the partial area based on the image data, and executes, a printing apparatus.

2. The partial area includes a scan area that is an area smaller than the partial area, the reference value is a printing duty of the scan area, wherein the control device executes a duty determination process of determining whether the printing duty is equal to or greater than a threshold value, and in the method determination process, when the printing duty is equal to or greater than the threshold value, determines that the method of the recording process is the multi-pass method, and when the printing duty is less than the threshold value, determines that the method of the recording process is the single-pass method. The printing apparatus according to Claim 1.

3. The partial area includes a plurality of scan areas that are areas smaller than the partial area, the reference value is a printing duty of the scan area, wherein the control device executes an area determination process of determining whether the number of scan areas in which the printing duty is equal to or greater than a threshold value in the partial area is equal to or greater than a predetermined number. and executes, In the mode determination process, if the number of regions is less than the predetermined number, the printing process is determined to be the single-pass mode, and if the number of regions is greater than or equal to the predetermined number, the printing process is determined to be the multi-pass mode. The printing apparatus according to claim 1.

4. The control device executes a threshold value acquisition process for acquiring the threshold value based on the dimension of the gap and the temperature information. The printing apparatus according to claim 2 or 3.

5. A plurality of nozzles for discharging ink onto a printing medium, and a head having a discharge surface through which the plurality of nozzles open; A moving device for moving the head; A conveying device for conveying the printing medium in a direction intersecting the moving direction of the head; A temperature sensor for detecting temperature; A maintenance unit for maintaining the nozzles; A control device, and includes: The control device: Based on image data, a printing process including a pass operation of discharging ink from the nozzles to a partial area of the printing medium while moving the head, and a conveying operation of conveying the printing medium; A gap acquisition process for acquiring the dimension of a gap between the printing medium and the discharge surface; A temperature acquisition process for acquiring temperature information of the head based on the detected temperature by the temperature sensor; A maintenance process for maintaining the nozzles by the maintenance unit after execution of the pass operation based on a reference value, the dimension of the gap, and the temperature information; A calculation process for calculating the reference value of the partial area based on the image data; executes. Printing apparatus.

6. The partial area includes a plurality of scan areas that are areas smaller than the partial area; The reference value is the printing duty of the scan area; The control device: A threshold value acquisition process for acquiring a threshold value based on the dimension of the gap and the temperature information; An area determination process for determining whether or not the number of scan areas in which the printing duty in the partial area is greater than or equal to the threshold value is greater than or equal to a predetermined number; executes, When the number of areas is greater than or equal to the predetermined number, the maintenance process is executed, and when the number of areas is less than the predetermined number, the maintenance process is not executed. The printing apparatus according to claim 5.

7. A plurality of nozzles for discharging ink onto a printing medium, and a head having a discharge surface through which the plurality of nozzles open; A moving device for moving the head; A conveying device that conveys the printing medium in a direction intersecting the moving direction of the head, A temperature sensor that detects temperature, A wiper that wipes the ejection surface, A cap that covers the ejection surface, A suction pump that sucks the space surrounded by the ejection surface and the cap, A control device, and includes: The control device, A maintenance process including a purge process of discharging ink from the nozzle by the suction pump and a wiping process of wiping the ejection surface by the wiper, A printing process including a pass operation of discharging ink from the nozzle to a partial area of the printing medium while moving the head based on image data and a conveying operation of conveying the printing medium, A gap acquisition process of acquiring the dimension of the gap between the printing medium and the ejection surface, A temperature acquisition process of acquiring temperature information of the head based on the detected temperature by the temperature sensor, Based on a reference value, the dimension of the gap, and the temperature information, the purge process or the wiping process as the maintenance process to be executed after the execution of the pass operation, A calculation process of calculating the reference value of the partial area based on the image data, Execute, Printing device.

8. The partial area includes a plurality of scan areas that are areas smaller than the partial area, The reference value is the printing duty of the scan area, The control device, A threshold acquisition process of acquiring a first threshold based on the dimension of the gap and the temperature information, An area determination process of determining whether or not a first area number, which is the number of scan areas in which the printing duty is equal to or greater than the first threshold in the partial area, is equal to or greater than a first predetermined number, Execute, When the first area number is equal to or greater than the first predetermined number, the maintenance process is executed, and when the first area number is less than the first predetermined number, the maintenance process is not executed, The printing device according to claim 7.

9. The control device, In the threshold acquisition process, a second threshold greater than the first threshold is acquired, In the area determination process, it is determined whether or not a second area number, which is the number of scan areas in which the printing duty is equal to or greater than the second threshold in the partial area, is equal to or greater than a second predetermined number, When the number of the second areas is equal to or greater than the second predetermined number, the purge process is executed as the maintenance process, and when the number of the second areas is less than the second predetermined number, the wiping process is executed as the maintenance process. The printing apparatus according to claim 8.

10. The temperature information is the temperature of the head detected by the temperature sensor, the ink ejection speed from the nozzle according to the temperature of the head, or the ink ejection method from the nozzle according to the temperature of the head, and includes. The printing apparatus according to claim 1, 5 or 7.

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