JP2007083450A - Print system and print method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a print system in which timing for performing flushing operation can be determined. <P>SOLUTION: The print system comprises a section for storing print data, a section for controlling a head to perform liquid drop ejecting operation from a nozzle based on the print data in order to print an image on a medium and to perform flushing operation for ejecting a liquid drop forcibly not to land in the medium wherein the control section determines the timing for performing the flushing operation after the starting printing of an image on the medium before ending the printing of the image based on the print data. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printing system and a printing method.

  2. Related Art Inkjet printers that print on a medium by ejecting a liquid (such as ink) from a nozzle to form dots on the medium (such as paper, cloth, or OHP sheet) are known. Such an ink jet printer is provided with a carriage that reciprocates during printing. Then, the ink jet printer ejects ink from the nozzles of the head that moves with the carriage, and causes the ejected ink droplets to land on the medium to perform a printing process.

In such an ink jet printer, a flushing operation is performed in order to suppress thickening of ink. The flushing operation is an operation for forcibly ejecting ink so as not to land on the medium and ejecting the ink to the ink receiving portion. By this flushing operation, the ink in the nozzles can be discharged, so that thickening of the ink can be suppressed.
JP 2000-127433 A

Conventionally, a time interval for performing the flushing operation is set, and the flushing operation is performed based on the time interval. In the flushing operation, the carriage is moved to the ink receiving portion to forcibly eject ink. Then, the carriage is moved again to the printing area at the time of printing and printing is resumed, which is one of the factors that increase the printing time.
Therefore, it is required to perform control so that the flushing operation is performed at a time when the printing time is not lengthened.
The present invention has been made in view of such circumstances, and an object of the present invention is to provide a printing system that can determine when to perform a flushing operation.

The main invention for solving the above problems is:
A storage unit for storing print data;
Flushing that forcibly ejects the liquid droplets so as not to land on the medium, the control unit for causing the head to perform an ejection operation of ejecting liquid droplets from the nozzles based on the print data and printing an image on the medium A control unit for causing the head to perform an operation,
The control unit is a printing system that determines, based on the print data, a timing for performing the flushing operation from the start of printing the image on the medium to the end of printing.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

=== Summary of disclosure ===
At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A storage unit for storing print data;
Flushing that forcibly ejects the liquid droplets so as not to land on the medium, the control unit for causing the head to perform an ejection operation of ejecting liquid droplets from the nozzles based on the print data and printing an image on the medium A control unit for causing the head to perform an operation,
The control unit, based on the print data, determines a timing for performing the flushing operation between the start of printing the image on the medium and the end of printing.
According to this printing system, it is possible to determine when to perform the flushing operation based on the print data.

  In this printing system, the control unit alternately repeats a discharge operation of discharging the liquid droplets from the nozzle and a transport operation of transporting the medium, and based on the print data, In a case where a transport operation for a predetermined transport time and a transport operation for a transport time longer than the predetermined transport time are performed, it is preferable that the flushing operation is performed during the transport operation for the long transport time. Further, it is desirable that the transport operation for the long transport time has a larger transport amount than the transport operation for the predetermined transport time. Further, the control unit obtains a non-ejection time, which is a time during which the nozzles do not eject the liquid droplets, based on the print data, and before the non-ejection time exceeds a predetermined time, It is desirable to determine to perform the flushing operation during the time transport operation. Further, when the control unit determines that the liquid droplet is not ejected from any nozzle in a certain ejection operation based on the print data, the conveyance amount of the next transportation operation in the transportation operation before the certain ejection operation The transport operation including the transport amount including the transport amount of the next transport operation is performed before the discharge operation is omitted by performing the transport operation for the long transport time with the transport amount including It is desirable to determine to perform the flushing operation when performing the transport operation for the long transport time by the amount. Further, it is desirable that the control unit determines to perform the flushing operation in a transport operation that is closest to the discharge operation up to the predetermined time. Further, it is preferable that the control unit determines to perform the flushing operation in a transport operation having the largest transport amount. In addition, it is desirable that the transport speed of the medium is slower in the transport operation of the long transport time than the transport operation of the predetermined transport time. In addition, the control unit obtains information related to slowing down the conveyance speed of the medium in the conveyance operation, and based on the information, before the non-ejection time exceeds the predetermined time, It is desirable to determine to perform the flushing operation when the speed is decreased. Further, the printing system includes a transport roller for transporting the medium in the transport operation, and the control unit, when an end on the upstream side of the transport direction of the medium passes through the transport roller, It is desirable to change the conveyance speed of the medium in the conveyance operation. In addition, when the control unit determines that the liquid droplet is not discharged from any nozzle in a certain discharge operation based on the print data, the next transport operation is transported in the transport operation before the certain discharge operation. When carrying out the carrying operation with a carrying amount including the amount and omitting the discharging operation, information on the carrying amount including the carrying amount of the next carrying operation is obtained, and the non-ejection time is determined based on the obtained information. Desirable. In addition, the control unit prints an end portion in the transport direction of the medium between the time when the liquid droplet is discharged and the time when the next liquid droplet is discharged. When performing the transport operation with a transport amount different from the transport amount of the transport operation, it is desirable to obtain information on the different transport amount and obtain the non-ejection time based on the information. In addition, the control unit acquires information related to the transport speed of the medium in the transport operation, and based on the information, the transport operation is performed after a liquid droplet is ejected until the next liquid droplet is ejected. It is desirable to obtain the non-ejection time when it is performed. The storage unit may store print data for one page of the medium. Accordingly, the printing system can determine when to perform the flushing operation based on the print data.

Storing print data;
Determining when to perform a flushing operation between the start of printing an image on a medium and the end of printing based on the print data;
Performing the flushing operation based on the determining step;
Including printing method.
According to this printing method, it is possible to determine when to perform flushing.

=== Configuration of Printing System 100 ===
<About the overall configuration>
First, the printing apparatus will be described together with the printing system 100. Here, FIG. 1 is a diagram illustrating the configuration of the printing system 100. The illustrated printing system 100 includes a printer 1 as a printing apparatus and a computer 110 as a printing control apparatus. Specifically, the printing system 100 includes a printer 1, a computer 110, a display device 120, an input device 130, and a recording / reproducing device 140. The printer 1 prints an image on a medium such as paper, cloth, or film. In the following description, a sheet S (see FIG. 3A), which is a typical medium, will be described as an example. The computer 110 is communicably connected to the printer 1. In order to cause the printer 1 to print an image, the computer 110 outputs print data corresponding to the image to the printer 1. Computer programs such as application programs and printer drivers are installed in the computer 110. The display device 120 has a display. The display device 120 is for displaying a user interface of a computer program, for example. The input device 130 is a keyboard 131 or a mouse 132, for example. The recording / reproducing device 140 is, for example, a flexible disk drive device 141 or a CD-ROM drive device 142.

=== Computer 110 ===
<Configuration of Computer 110>
FIG. 2 is a block diagram illustrating the configuration of the printing system 100 including the computer 110 and the printer 1. First, the configuration of the computer 110 will be briefly described. The computer 110 includes the recording / reproducing device 140 and the host-side controller 111 described above. The recording / reproducing apparatus 140 is communicably connected to the host-side controller 111, and is attached to the housing of the computer 110, for example. The host-side controller 111 performs various controls in the computer 110, and the display device 120 and the input device 130 described above are also connected to be communicable. The host-side controller 111 includes an interface unit 112, a CPU 113, and a memory 114. The host-side controller 111 corresponds to a control unit that determines when to perform the flushing operation. The interface unit 112 is interposed between the printer 1 and exchanges data. The CPU 113 is an arithmetic processing unit for performing overall control of the computer 110. The memory 114 is used to secure an area for storing a computer program used by the CPU 113, a work area, and the like, and includes a RAM, an EEPROM, a ROM, a magnetic disk device, and the like. As described above, computer programs stored in the memory 114 include application programs and printer drivers. The CPU 113 performs various controls according to the computer program stored in the memory 114.

=== Printer 1 ===
<About the configuration of the printer 1>
Next, the configuration of the printer 1 will be described. Here, FIG. 3A is a diagram illustrating a configuration of the printer 1 of the present embodiment. FIG. 3B is a cross-sectional view illustrating the configuration of the printer 1 of the present embodiment. In the following description, FIG. 2 is also referred to. As shown in FIG. 2, the printer 1 includes a paper transport mechanism 20, a carriage moving mechanism 30, a head unit 40, a detector group 60, and a printer-side controller 70. The printer-side controller 70 corresponds to a control unit that forms an image on a medium by causing the head to perform an ejection operation of ejecting liquid droplets from the nozzles. That is, in this embodiment, the host of the printing system 100 has a function of determining when to perform flushing, which is a function as a control unit, and a function of causing the head to perform a liquid droplet ejection operation to form an image on a medium. The side controller 111 and the printer side controller 70 are shared. In the printer 1, the control target unit, that is, the paper transport mechanism 20, the carriage moving mechanism 30, and the head unit 40 are controlled by the printer-side controller 70. That is, the printer-side controller 70 controls the control target unit based on the print data received from the computer 110 and prints an image on the paper S. At this time, each detector of the detector group 60 detects the state of each part in the printer 1 and outputs the detection result to the printer-side controller 70. Upon receiving the detection results from each detector, the printer-side controller 70 controls the control target unit based on the detection results.

<Regarding the paper transport mechanism 20>
The paper transport mechanism 20 corresponds to a medium transport unit that transports a medium. The paper transport mechanism 20 feeds the paper S as a medium to a printable position, or transports the paper S by a predetermined transport amount in the transport direction. This transport direction is a direction that intersects the carriage movement direction described below. 3A and 3B, the paper transport mechanism 20 includes a paper feed roller 21, a transport motor 22, a transport roller 23, a platen 24, a paper discharge roller 25, and a driven roller 26. The paper feed roller 21 is a roller for automatically feeding the paper S inserted into the paper insertion opening into the printer 1 and has a D-shaped cross section in this example. The carry motor 22 is a motor for carrying the paper S in the carrying direction, and its operation is controlled by the printer-side controller 70. The transport roller 23 is a roller for sandwiching the paper S sent by the paper feed roller 21 between the driven roller 26 and transporting it to a printable area. The platen 24 is a member for supporting the paper S from the back side. The paper discharge roller 25 is a roller for carrying the paper S that has been printed.

<About the carriage moving mechanism 30>
The carriage moving mechanism 30 is for moving the carriage CR to which the head unit 40 is attached in the carriage moving direction. The carriage movement direction includes a movement direction from one end side to the other end side and a movement direction from the other end side to the one end side. The head unit 40 has a head 41. The carriage moving mechanism 30 includes a carriage motor 31, a guide shaft 32, a timing belt 33, a drive pulley 34, and an idler pulley 35. The carriage motor 31 corresponds to a drive source for moving the carriage CR. The operation of the carriage motor 31 is controlled by the printer-side controller 70. A drive pulley 34 is attached to the rotation shaft of the carriage motor 31. The drive pulley 34 is disposed on one end side in the carriage movement direction. An idler pulley 35 is disposed on the other end side in the carriage movement direction on the opposite side to the drive pulley 34. The timing belt 33 is an annular member whose end is fixed to the carriage CR, and is spanned between a drive pulley 34 and an idler pulley 35. The guide shaft 32 supports the carriage CR in a movable state. The guide shaft 32 is attached along the carriage movement direction. Accordingly, when the carriage motor 31 operates, the carriage CR moves along the guide shaft 32 in the carriage movement direction. Along with this, the head 41 also moves in the head moving direction.

  An ink cartridge IC for storing ink is mounted on the carriage CR. The ink cartridge IC of the present embodiment includes a black ink cartridge ICk that stores black ink, and a color ink cartridge ICc that stores color ink. The color ink cartridge ICc stores three types of ink. Specifically, cyan ink, magenta ink, and yellow ink are stored.

<About the head unit 40>
The head unit 40 is for ejecting ink onto paper. The head unit 40 has a head 41. The head 41 has a plurality of nozzles, and ejects ink intermittently from each nozzle. The head 41 is provided on the carriage CR. Therefore, when the carriage CR moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot rows (raster lines) along the moving direction are formed on the paper.

<About the head 41>
FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of the head 41. On the lower surface of the head 41, a black ink nozzle group K, a cyan ink nozzle group C, a magenta ink nozzle group M, and a yellow ink nozzle group Y are formed. Each nozzle group includes a plurality of nozzles that are ejection openings for ejecting ink of each color. The plurality of nozzles of each nozzle group are aligned at a constant interval (nozzle pitch: k · D) along the transport direction. Here, D is the minimum dot pitch in the carrying direction (that is, the interval at the highest resolution of dots formed on the paper S). K is an integer of 1 or more. For example, when the nozzle pitch is 180 dpi (1/180 inch) and the dot pitch in the transport direction is 720 dpi (1/720 inch), k = 4. The nozzles of each nozzle group are assigned a smaller number as the nozzles on the downstream side (# 1 to # 180). Each nozzle is provided with an ink chamber (not shown) and a piezo element (not shown). The ink chamber is expanded and contracted by driving the piezo element, and ink droplets are ejected from the nozzle.

<Regarding the detector group 60>
The detector group 60 is for monitoring the status of the printer 1. As shown in FIGS. 3A and 3B, the detector group 60 includes a linear encoder 61, a rotary encoder 62, a paper detector 63, and a paper width detector 64. The linear encoder 61 is for detecting the position of the carriage CR in the carriage movement direction. The rotary encoder 62 is for detecting the rotation amount of the transport roller 23. The paper detector 63 is for detecting the paper S to be printed. The paper detector 63 plays a role of detecting the presence or absence of paper in BS control described later. The paper width detector 64 is for detecting the width of the paper S to be printed.

<About the printer-side controller 70>
The printer-side controller 70 controls each unit included in the printer 1. For example, the printer-side controller 70 alternately performs an operation of transporting the paper S by a predetermined transport amount and an operation of intermittently ejecting ink while moving the carriage CR (head 41). Is printing an image. Therefore, the printer-side controller 70 controls the conveyance of the paper S by controlling the rotation amount of the conveyance motor 22. The printer-side controller 70 controls the movement of the carriage CR by controlling the rotation of the carriage motor 31. Further, the printer-side controller 70 performs control for causing the head to eject ink using the dot formation data.

  As shown in FIG. 2, the printer-side controller 70 includes an interface unit 71, a CPU 72, a memory 73, and a control unit 74. The interface unit 71 exchanges data with the computer 110 which is an external device. The CPU 72 is an arithmetic processing unit for performing overall control of the printer 1. The memory 73 is for securing an area for storing a program of the CPU 72, a work area, and the like, and is configured by a storage element such as a RAM, an EEPROM, or a ROM. Then, the CPU 72 controls each control target unit in accordance with the computer program stored in the memory 73. For example, the CPU 72 controls the paper transport mechanism 20 and the carriage movement mechanism 30 via the control unit 74. For example, control signals for the transport motor 22 and the carriage motor 31 are output.

=== Basic printing operation ===
The printing system 100 according to the present embodiment is used in, for example, the following printing operation.

<About printing operation>
FIG. 5 is a flowchart of processing during printing. Each process described below is executed by the printer-side controller 70 controlling each unit in accordance with a program stored in the memory 73. This program has a code for executing each process.

  Print Command Reception (S501): First, the printer-side controller 70 receives a print command from the computer 110 via the interface unit 71. This print command is included in the header of print data transmitted from the computer 110. Then, the printer-side controller 70 analyzes the contents of various commands included in the received print data, and performs the following paper feed processing / conveyance processing / dot formation processing using each unit.

  Paper Feed Process (S502): The paper feed process is a process for supplying paper to be printed into the printer and positioning the paper at a print start position (also referred to as a cue position). The printer-side controller 70 rotates the paper feed roller 21 and the transport roller 23 to position the paper at the print start position. In addition, while the paper is positioned at the print start position, the head 41 performs a flushing operation to eliminate the thickening of the ink droplets.

  Dot Forming Process (S503): The dot forming process is a process for forming dots on the paper by intermittently ejecting ink from the head 41 moving along the moving direction. The printer-side controller 70 drives the carriage motor 31 to move the carriage CR in the movement direction, and ejects ink from the head 41 based on the pixel data included in the print data while the carriage CR is moving. When ink droplets ejected from the head 41 land on the paper, dots are formed on the paper. Since ink is intermittently ejected from the moving head 41, a dot row (raster line) composed of a plurality of dots along the moving direction is formed on the paper.

  Transport Process (S504): The transport process is a process of moving the paper relative to the head along the transport direction. The printer-side controller 70 rotates the transport roller 23 to transport the paper in the transport direction. By this carrying process, the head 41 can form dots in the next dot forming process at a position different from the position of the dots formed by the previous dot forming process.

  Paper discharge determination (S505): The printer-side controller 70 determines whether or not to discharge the paper being printed. If data to be printed remains on the paper being printed, no paper is discharged. Then, the printer-side controller 70 alternately repeats the dot formation process and the conveyance process until there is no more data to be printed, and gradually prints an image composed of dots on paper.

  Paper Discharge Process (S506): When there is no more data to be printed on the paper being printed, the printer-side controller 70 discharges the paper by rotating the paper discharge roller. The determination of whether or not to discharge the paper may be based on a paper discharge command included in the print data.

  Print end determination (S507): Next, the printer-side controller 70 determines whether or not to continue printing. If printing is to be performed on the next paper, printing is continued and the paper feeding process for the next paper is started. If printing is not performed on the next paper, the printing operation is terminated.

<Interlaced printing>
9A and 9B are explanatory diagrams of interlaced printing. FIG. 9A shows the position of the head (or nozzle group) in pass 1 to pass 4 and how dots are formed, and FIG. 9B shows the position of the head in pass 1 to pass 6 and how dots are formed. .

  For convenience of explanation, only one nozzle group of a plurality of nozzle groups is shown, and the number of nozzles in the nozzle group is also reduced (eight here). The nozzles indicated by black circles in the figure are nozzles that can eject ink. On the other hand, nozzles indicated by white circles are nozzles that cannot eject ink. For convenience of explanation, the head (or nozzle group) is depicted as moving with respect to the paper, but this figure shows the relative position of the head and the paper. The paper is moved in the transport direction. Also, for convenience of explanation, each nozzle is shown as having only a few dots (circles in the figure), but in reality, ink droplets are ejected intermittently from nozzles that move in the direction of movement. Therefore, a large number of dots are arranged in the moving direction. This row of dots is also called a raster line. A dot indicated by a black circle is a dot formed in the last pass, and a dot indicated by a white circle is a dot formed in a previous pass. Note that “pass” refers to an operation (dot formation operation) in which ink is ejected from a moving nozzle to form dots. Each pass is alternately performed with an operation (conveying operation) for conveying the paper in the conveying direction.

  “Interlaced printing” means a printing method in which k is 2 or more and a raster line that is not recorded is sandwiched between raster lines that are recorded in one pass. For example, in the printing method in FIGS. 9A and 9B, three raster lines are sandwiched between raster lines formed in one pass.

  In interlace printing, each time the paper is transported in the transport direction by a constant transport amount F, each nozzle records a raster line immediately above the raster line recorded in the immediately preceding pass. In order to perform recording with a constant carry amount in this way, (1) the number N (integer) of nozzles that can eject ink is relatively prime to k, and (2) the carry amount F is N · The condition is that it is set to D.

  In the figure, the nozzle group has eight nozzles arranged along the transport direction. Since the nozzle pitch k of the nozzle group is 4, in order to satisfy the condition for performing interlaced printing, “N and k are prime to each other”, all nozzles are not used and seven nozzles (nozzles # 1 to # 1) are used. Nozzle # 7) is used. Further, since seven nozzles are used, the paper is transported with a transport amount of 7 · D. As a result, using a nozzle group having a nozzle pitch of 180 dpi (4 · D), dots are formed on the paper at a dot interval of 720 dpi (= D). Since the actual number of nozzles (180) is greater than 7, the actual transport amount (179 · D) is greater than 7 · D.

  In the case of interlace printing, k passes are required to complete a raster line having a continuous nozzle pitch width. For example, in order to complete four raster lines that are continuous at a dot interval of 720 dpi using a nozzle group having a nozzle pitch of 180 dpi, four passes are required. According to the figure, continuous raster lines are formed at dot intervals D upstream of the raster line (raster line indicated by the arrow in the figure) formed by nozzle # 2 in pass 3 in the transport direction. It has been shown.

<Print data generation processing>
In the present embodiment, the printing system 100 converts image data into print data, and performs dot formation processing based on the print data. That is, in the present embodiment, the print data includes data that has been finally rasterized. The print data generation process will be described below.
FIG. 6 is a flowchart of the print data generation process. These processes are performed by the printer driver.

  First, the printer driver performs resolution conversion processing (S601). The resolution conversion process is a process for converting image data (text data, image data, etc.) output from an application program into a resolution for printing on paper. For example, when the resolution when printing an image on paper is specified as 720 × 720 dpi, the image data received from the application program is converted into image data having a resolution of 720 × 720 dpi. Note that the image data after the resolution conversion process is 256-gradation data (RGB data) represented by an RGB color space.

  Next, the printer driver performs color conversion processing (S602). The color conversion process is a process for converting RGB data into CMYK data represented by a CMYK color space. This color conversion process is performed by the printer driver referring to a table (color conversion lookup table LUT) in which the gradation values of RGB data and the gradation values of CMYK data are associated with each other. Through this color conversion process, RGB data for each pixel is converted into CMYK data corresponding to the ink color. The data after the color conversion processing is CMYK data with 256 gradations represented by the CMYK color space.

  Next, the printer driver performs halftone processing (S603). The halftone process is a process for converting high gradation number data into gradation number data that can be formed by a printer. For example, data indicating 256 gradations is converted into 1-bit data indicating 2 gradations by halftone processing. In the halftone process, pixel data is created by using a dither method, γ correction, error diffusion method, or the like so that the printer can form dots dispersedly. When performing halftone processing, the printer driver refers to the dither table when performing dithering, refers to the gamma table when performing γ correction, and stores diffused errors when performing error diffusion. Refer to the error memory. The data subjected to the halftone process has a resolution (for example, 720 × 720 dpi) equivalent to the RGB data described above.

  Next, the printer driver performs rasterization processing (S604). The rasterization process is a process of changing matrix image data in the order of data to be transferred to the printer. FIG. 13 is a diagram showing raster data of nozzles # 1 to # 180 in pass 1 to pass n. Here, raster data from nozzle # 1 to nozzle # 180 is shown for each pass. Raster data is data corresponding to pixels arranged in the moving direction of the head. The pixel includes a pixel in which a dot is formed (dot formed pixel) and a pixel in which no dot is formed (dot non-formed pixel). In FIG. 13, black circles indicate pixel data of dot formation pixels, and white circles indicate pixel data of non-dot formation pixels. These data are created for each pass based on interlace map data in which the positions in charge of pixel formation for each nozzle are recorded.

In FIG. 13, the number of pixels in the X direction is reduced for ease of explanation. The actual number of pixels in the actual X direction is much larger than this.
FIG. 14 is a diagram illustrating print data according to the present embodiment. The print data is composed of print data for each pass, and each print data includes raster data and command data for nozzles # 1 to # 180. In the raster data, 1 corresponds to the pixel data of the dot formation pixel, and 0 corresponds to the pixel data of the dot non-formation pixel. In the present embodiment, transport amount information, BS control information, and skip information are recorded as command data. The print data is created by adding these command data after the raster data is generated.

In this embodiment, since the carriage CR holds a head having nozzles for four colors of black K, cyan C, magenta M, and yellow Y, the command data for each pass is common to the colors. . Therefore, it is also possible to add command data only to the black K print data, and to control medium conveyance or the like according to the command data.
The print data generated by the print data generation process is stored on the memory 114 of the computer 110.

<Skip control>
In some passes, ink is not ejected from nozzles of all colors. In such a case, it is possible to shorten the printing time by performing only the transport operation of the paper S without performing a pass. Since control for skipping the path is performed, such control is called skip control in the present embodiment. Further, a path from which a path is omitted is called a skip path for convenience of explanation.

  FIG. 11 is a diagram for explaining the carry amount during normal printing and the carry amount when skip control is performed. For example, when the transport amount is 7 · D, skip control is not normally performed, and the transport is performed with a transport amount of 7 · D as shown on the left side of FIG. On the other hand, when skip control is performed, the path (k + 1) 'is omitted as shown on the right side of FIG. That is, 14 · D conveyance is performed at a time from the pass k ′ to the pass (k + 2) ′.

  Whether to perform the skip control is determined based on the skip information of the print data. In the present embodiment, skip control is performed on the assumption that the print data pass with skip information 1 is not performed. Here, the skip information is set to 1 when all raster data is 0 for all colors. In other words, 1 is set for a pass in which ink is not ejected from any nozzle for all colors.

<Flushing operation>
The “flushing” operation is an operation for forcibly ejecting ink so as not to land on a medium (paper, cloth, OHP sheet, etc.) and ejecting the ink to an ink receiving portion. By performing the flushing operation, it is possible to discharge the ink in the nozzles that are not in use, and thus it is possible to suppress an increase in the viscosity of the ink.

  7A to 7D are explanatory diagrams of the flushing operation. 7A to 7D are views seen from the paper feeding side of the paper S of the printer 1 of the present embodiment. FIG. 7A is an explanatory diagram showing a stop position of the carriage CR before the dot formation process. FIG. 7B is an explanatory diagram of ink landing during printing. FIG. 7C is an explanatory diagram showing the stop position of the carriage CR after the dot formation processing. FIG. 7D is an explanatory diagram of the flushing operation of the carriage CR. Since the components already described are given the same reference numerals, the description thereof is omitted.

  During the dot formation process (FIG. 5, S503), the carriage CR operates as follows. First, before performing the dot formation process, the carriage CR stops at a position outside the right end of the paper (a position where the lower surface of the head 41 does not face the paper S) as shown in FIG. 7A. Then, the carriage CR accelerates toward the left in the drawing and moves at a constant speed at a predetermined speed. Then, when the carriage CR is moving at a constant speed, ink ejection is started from the nozzles of the head 41 so as to land on the paper S as shown in FIG. 7B. When the ink ejection is finished and the dot formation process is finished, the carriage CR decelerates. Then, as shown in FIG. 7C, the carriage CR stops at a position outside the left end of the paper (a position where the lower surface of the head 41 does not face the paper S).

  When the dot formation process is repeatedly performed, the carriage CR returns from the stop position in FIG. 7C and moves toward the right in the drawing to perform the dot formation process. When the dot formation process is completed, the ink ejection is completed, the carriage CR is decelerated, and stops at the stop position in FIG. 7A. Thus, when the dot forming process is repeatedly performed, the carriage CR reciprocates between the stop position in FIG. 7A and the stop position in FIG. 7C.

  In the present embodiment, an ink receiving portion 701 is provided outside the range of carriage reciprocation during dot formation processing (see FIGS. 7A to 7D). The ink receiving portion 701 is provided with an absorbing member 702 for absorbing ink ejected by the flushing operation.

  In a conventional printing apparatus, this flushing operation is performed at a predetermined time such as once every several tens of seconds. The time from the completion of a certain flushing operation to the next flushing operation varies depending on the characteristics of the head, such as the shape of the nozzle and the size of the nozzle, in addition to the properties of the ink. The predetermined time is set so that the image formation is not affected by the thickening of the ink without discharging the ink droplets. In the present embodiment, the predetermined time defined for performing the flushing operation in this way is defined as a “flushing limit time”. The flushing limit time is set to a value obtained through experiments or the like. In this embodiment, the flushing limit time is set to 9 (s).

  Conventionally, when the flushing limit time has elapsed, the flushing operation is performed even during printing. When performing the flushing operation, the carriage CR must be moved to the ink receiving portion 701 provided outside the range of reciprocal movement of the carriage during the dot formation process. For this reason, if the flushing operation is performed during printing, the printing operation is interrupted in the middle, and the printing time becomes longer due to the reciprocation time from the interruption position to the ink receiving portion.

However, even when the flushing operation must be performed, if the flushing operation is performed when the paper is transported for a longer time than usual, a part of the time of the flushing operation can be incorporated during the transport time. And the overall printing time can be shortened.
Therefore, in this embodiment, the printing time is shortened by performing the flushing operation when the transport time of the paper S is longer than usual during printing. A method for determining when to perform the flushing operation according to the present embodiment will be described below.

=== Judgment Method of Time of Flushing Operation ===
=== First Embodiment ===
First, an outline of a method for determining the timing of the flushing operation in the present embodiment will be described. In the present embodiment, a non-ejection period that causes a non-ejection time is obtained using a certain pass (reference pass) as a reference for starting printing. Next, a non-ejection section that first exceeds the flushing limit time is identified from the determined non-ejection sections. Then, the flushing information is set so that the flushing operation is started from the transport operation immediately before the skip path (pass where the path is omitted) that exists in the non-ejection interval and does not exceed the flushing limit time.

The flushing information is information indicating whether or not the flushing operation is performed during the transport operation subsequent to the pass. At the time when the print data is generated, 0 is recorded in the flushing information. Then, as a result of determining the timing of performing the flushing operation by a method described later, 1 is set in the flushing information of the pass immediately before the transport operation for performing the flushing operation. During the printing operation, the flushing operation is performed in the transport operation immediately after the pass in which the flushing information is 1.
When 1 is set in the flushing information, the position of the reference path is moved in order to specify the next time to perform the flushing operation. Then, by repeating the above-described processing, the timing of the transport operation for performing the next flushing operation is specified. Note that the first reference path starts as path 1.

  Next, a method for determining the timing of the flushing operation in the present embodiment will be described. FIG. 15 is a flowchart of the determination program for the timing of the flushing operation of the present embodiment. This flow is realized by executing a program stored in the memory 114 by the CPU 113 of the host-side controller 111 after the above-described print data generation processing is completed. The print data used here is print data for one page of paper, and is stored in the memory 114. Here, description will be given by taking nozzle # 1 and nozzle # 2 as an example.

  When the program for determining the timing of the flushing operation is executed, the CPU 113 calculates the non-ejection time of each nozzle (S1502). There are two cases of the non-ejection time: the time from the completion of the flushing operation to the pass having the first dot formation pixel and the time from the pass having the dot formation pixel to the pass having the next dot formation pixel. .

  FIG. 16 is a diagram for explaining the calculation of the non-ejection time. FIG. 16 shows the position of the head during the flushing operation and in pass 1 to pass 4. For convenience of explanation, the head is depicted as moving, but the figure shows the relative position between the head and the paper, and the paper S that is the medium is actually moving. In the same figure, the head is drawn with the nozzles omitted. Further, the position at the time of the flushing operation is also drawn above the position of the pass 1, but actually the flushing operation is performed at the ink receiving portion as described above.

Referring to FIG. 16, the time from the completion of the flushing operation to the first pass is represented by T _fl , and the time from one pass to the next pass is represented by t _pa . Further, the time from the skip path to the next path when the path is omitted is represented by _tpb . Therefore, the time from the completion of the flushing operation to the pass in which the first dot formation pixel exists and the time from the pass in which the dot formation pixel exists to the next pass in which the dot formation pixel exists are expressed as T _fl , t It can be obtained by taking the sum of _pa and t _pb as appropriate.

  In S1502, a non-ejection time calculation routine is called to obtain the non-ejection time. FIG. 17 is a flowchart of the non-ejection time calculation routine of this embodiment. When the non-ejection time calculation routine is called, the CPU 113 searches for and specifies the first pass in which dot formation pixels exist (S1702). The search method is performed by examining whether or not dot formation pixel data exists in order from the left in the raster data from the reference pass (pass 1) to the final pass for each nozzle. FIG. 18 is a diagram illustrating an example of print data. For example, referring to the figure, for nozzle # 1, there is dot formation pixel data fourth in the raster data for pass 1. Therefore, the first pass where the dot formation pixel exists is specified as pass 1. On the other hand, for nozzle # 2, there is no dot formation pixel in any pass. Therefore, in this case, the first pass where the dot formation pixel exists cannot be specified.

  Next, the CPU 113 determines whether or not there is a first pass in which dot formation pixels exist (S1704). For nozzle # 1 described above, since pass 1 is specified as the first pass in which dot formation pixels exist, the flow proceeds to S1706. On the other hand, in the case of nozzle # 2, since the dot formation pixel does not exist, the flow proceeds to S1720.

When the first pass where the dot formation pixel exists can be found, the CPU 113 obtains the time from the completion of the first flushing operation to the first pass where the dot formation pixel exists (S1706). The time from the completion of the flushing operation to the first pass where the dot formation pixel exists is the time from the completion of the flushing operation to the pass 1 and the time from the pass 1 to the first pass where the dot formation pixel exists. It can be calculated as the sum of Here, it is assumed that pass 1 is the first pass, and the first pass where the dot formation pixels exist is the second pass. Then, the time T _total from the completion of the first flushing operation to the second pass is _equal to the time T _fl from the completion of the first flushing operation to the pass 1 and from the first pass to the second pass. Since it can be expressed as the sum of the time T _1to2 ,

_{T total = T fl + T 1to2} (1)

It becomes. The time from the completion of the flushing operation to pass 1 is determined by factors such as the performance of the carriage motor 31 and the movable width of the carriage CR, and is a unique time of the printer 1. In the printer 1 according to the present embodiment, the time T _fl from the completion of the flushing operation to the pass 1 is set to 0.2 (s).

The time T _1to2 from the first path to the second path is _{expressed as} follows: the first path number is P ₁ and the second path number is P ₂ , and the time from one path to the next path is t _pa . To do. Also, if the number of skip paths from the first path to the second path is N _skp and the time from the skip path to the next path is t _pb ,

T _1to2 = (P ₂ −P ₁ −N _skp ) · t _pa + N _skp · t _pb (2)

It becomes. In this embodiment, the time t _pa from one path to the next path is 1.0 (s), and the time t _pb from the skip path to the next path is 0.8 (s).

Here, since the path 1 is the first path, the first path number is 1. In step S <b> 1702, the CPU 113 finds the dot formation pixel data in the fourth pass 1. Therefore, the pass number 1 is set as the second pass number. Then, since P ₂ and P ₁ are 1, the time from the first pass to the second pass is 0 (s). Further, the time T _fl from the completion of the first flushing operation to the pass 1 is 0.2 (s). Therefore, by substituting these into equation (1), the time from the completion of the first flushing operation to the second pass is 0.2 (s).

In this way, when the time from the completion of the first flushing operation to the second pass is obtained, the CPU 113 records the obtained value together with the non-ejection period in the non-ejection time table (S1708). FIG. 20 is an example of a non-ejection time table. This non-ejection time table is a table for recording the non-ejection time of ink for each nozzle, and is stored in the memory 114. FIG. 20 shows only the non-ejection time table for the black K nozzle 1, but it is prepared and recorded for all the color nozzles # 1 to # 180.
For example, in this case, for nozzle # 1, the time required from the completion of the first flushing operation to the second pass was 0.2 (s), so 0 is set to nozzle # 1 in the non-ejection time table. .2 (s) is recorded. In the non-ejection section, “(first pass) to (second pass)” is recorded. However, here, since it is the first process, the number of the first pass is set to 0.

  Next, the CPU 113 searches for and specifies the next pass in which the dot formation pixel exists (S1710). Referring to FIG. 21, for nozzle 1, dot formation pixel data exists in the sixth of the raster data for pass 2. Therefore, pass 2 is specified as the next pass in which dot formation pixels exist.

  Next, the CPU 113 determines whether or not there is a next pass in which dot formation pixels exist (S1712). For the nozzle # 1 described above, since the pass 2 is specified as the next pass in which the dot formation pixels exist, the flow proceeds to S1714. On the other hand, when the next pass where the dot formation pixel exists is not found, this flow is finished.

When the CPU 113 finds the next pass in which the dot formation pixel exists, the CPU 113 sets the previous second pass number P ₂ to the first pass number P _1, and sets the pass in which the dot formation pixel found this time exists. setting the number as the number _{P 2} of the second pass (S1714). For example, the next pass where the dot formation pixel found this time exists is pass 2. Therefore, the CPU 113 sets 1 which was the number of the second pass as the number P1 of the _first pass, and the pass number 2 of the next pass where the dot formation pixel exists is the number P2 of the _second pass. Set to.

The CPU 113 substitutes these values into the equation (2) to obtain a time T _1to2 from the first pass to the second pass (S1716). Since the flushing operation is performed immediately before the printing operation, the time from the first pass to the second pass is not necessary in the calculation after S1710 without considering the time _Tfl from the completion of the flushing operation to the pass 1. You can ask for. Here, since the number P ₁ of the first path is 1 and the number P ₂ of the second path is 2, the time T _1to2 from the first path to the second path is 1.0. (S).

Next, the CPU 113 _records the obtained T _1to2 value together with the non-ejection interval in the non-ejection time table (S1718). The value of T _1to2 obtained this time was 1.0 (s). Therefore, 1.0 (s) is recorded as the non-ejection time from pass 1 to pass 2.

  Next, the flow returns to S1710. And the non-ejection time table for every position of Drawing 20 is created by repeating the above-mentioned procedure. Finally, in S1712, a path in which dot formation pixels exist cannot be found. At that point, this routine ends.

  By the way, when the first pass where the dot formation pixel exists is not found in any search in S1704, the CPU 113 records 0 (s) in the non-ejection time table (S1720). When there is no first pass in which dot formation pixels exist, this nozzle will not eject ink droplets even while printing one page of paper S. Then, since this nozzle does not perform image formation, it is not necessary to perform a flushing operation for this nozzle. Therefore, since it is not necessary to refer to the non-ejection time of the nozzle in order to determine the timing for performing the flushing operation, 0 (s) that does not affect the determination described later is recorded.

  In this way, when the non-ejection time is obtained for all the nozzles, the CPU 113 determines whether or not there is a non-ejection time exceeding the flushing limit time in the obtained non-ejection time (S1504). If none of the determined non-ejection times exceed the flushing limit time, it is not necessary to perform the flushing operation while printing one page of the paper S, and thus this program is terminated. On the other hand, when the calculated non-ejection time exceeds the flushing limit time, the CPU 113 advances the flow to step S1506.

  In step S1506, the CPU 113 first identifies a non-ejection section corresponding to the non-ejection time exceeding the flushing limit time that exceeds the flushing limit time (S1506). Specifically, the non-ejection section that causes the non-ejection time exceeding the flushing limit time is identified as the one with the smallest first pass number (the one at the uppermost end). The reason for this is that the non-ejection time of the first pass having the smallest pass number in the non-ejection period corresponding to the non-ejection time exceeding the flushing limit time exceeds the flushing limit time earliest during printing. Become. Therefore, in order to set to perform the flushing operation before this, in S1506, the non-ejection section having the smallest first pass is specified.

  FIG. 21 is a diagram for explaining the processing in step S1506. FIG. 21 shows a non-ejection time table for nozzle # 1 and nozzle # 2. Here, for the sake of simplicity of explanation, only two nozzles, nozzle # 1 and nozzle # 2, are described. Referring to the figure, it is pass 2 to pass 15 and pass 70 to pass 93 that exceed the flushing limit time for nozzle # 1. For nozzle # 2, pass 19 to pass 35, and pass 72 to pass 92. Among these, the non-ejection section having the smallest first pass number is when nozzle # 1 passes 2 to 15. Therefore, in the non-ejection period that causes the non-ejection time exceeding the flushing limit time, the passes 2 to 15 are first identified as exceeding the flushing limit time.

Next, in the non-ejection period (pass 2 to pass 15) specified in S1506, the CPU 113 sets the flushing information so that the flushing operation is performed in the transport operation immediately before the skip pass existing in the range not exceeding the flushing limit time. The setting is made (S1508). Specifically, a path that exceeds the flushing limit time is identified with reference to the first path of the non-ejection section identified in S1506 (the identified path is referred to as a specific path for convenience). Next, the skip path closest to the specific path is searched for among the skip paths existing from the first path to the specific path. Then, 1 is set in the flushing information of the path immediately before the skip path so that the flushing operation is performed in the transport operation immediately before the searched skip path.
The method for obtaining a specific path that exceeds the flushing limit time is as follows. As described above, the time t _pa from one path to the next path and the time t _pb from the skip path to the next path are known. Therefore, the CPU 113 accumulates the time from the first pass to the next pass sequentially while referring to the skip information. Then, a path whose accumulated time exceeds the flushing limit time is specified.

  FIG. 19 shows skip information extracted in the non-ejection section path. For example, when integration from the first pass is performed with reference to FIG. 19, the time from pass 2 to pass 3 is 1.0 (s) because the skip information of pass 2 is 1. Next, the time from pass 2 to pass 4 is 1.8 (s) because the skip information of pass 3 is 1. In this way, when the integration of time is repeated from the first pass, it is understood that 9.8 (s) is required in pass 2 to pass 13 and the flushing limit time is exceeded. Therefore, the path 13 is a specific path, and the flushing path from the first path to the specific path is selected closest to the specific path. In the figure, the skip paths between the first path and the specific path are paths 3, 4, 7, 8, 9, and 11. At this time, since the skip path closest to the specific path (path 13) is path 11, a value 1 is set in the flushing information of path 10 so that the flushing operation is performed in the immediately preceding transport operation.

  Incidentally, there may be a case where no skip path exists between the first path and the specific path. In this case, on the basis of the first pass, the flushing information is set so that the flushing operation is performed in the transport operation immediately before the pass in which the flushing limit time elapses. However, in this case, since a part of the flushing operation cannot be incorporated into the skip path, it does not contribute to shortening the printing time.

Next, the current reference path is changed to determine when to perform the next flushing operation. Specifically, the number of a path (excluding the skip path) that is first encountered after the transport operation in which the flushing operation is performed is set as a new reference path number (S1510).
This time, the flushing operation was started in the transport operation immediately after the pass 10. Referring to FIG. 19, the first path encountered after the path 10 (excluding the skip path) is the path 12. Therefore, the path 12 is set as a new reference path.

  When the process of S1510 is completed, the CPU 113 returns the flow to S1502. By repeating the flow in this way, the timing for performing the flushing operation is set.

  In this way, the flushing operation can be started from the transport operation immediately before the skip path. As a result, a part of the time for the flushing operation can be incorporated into the transport time of the skip pass, and the entire printing time can be shortened.

=== Second Embodiment ===
In the first embodiment, when selecting a path that can be skip-controlled in S1508, the skip path closest to the specific path is selected from among the skip paths existing between the first path and the specific path. In the second embodiment, when selecting a path that can be skip-controlled in step S1508, the skip path group in which the skip path is the most continuous from the first path to the specific path is specified, and the flushing of the path immediately before the skip path group is specified. A value of 1 is set in the information.

Referring to FIG. 19, between the first path (path 2) and the specific path (path 13), there are two consecutive skip path groups: path 3 to path 4 and path 7 to path 9. Existing. Comparing the two, it is the paths 7 to 9 that have the most skip paths. Therefore, here, the value 1 is set to the flushing information of the pass 6 so that the flushing operation is performed in the transport operation immediately before the skip pass 7.
In this way, a part of the flushing operation can be incorporated during a long carrying operation, so the printing time per page of paper S can be shortened.

=== Third Embodiment ===
In the first embodiment described above, the non-ejection time is the time from the ink ejection pass to the next pass of ink ejection. In the third embodiment, in order to obtain a more accurate non-ejection time, (1) the time from the completion of the flushing operation until the head reaches the position of the first dot formation pixel, or (2) a certain dot formation The moving time of the head from the position of the pixel to the position of the next dot formation pixel is defined as a non-ejection time. The third embodiment is different from the first embodiment in the non-ejection time calculation (S1502) routine in FIG. Since other parts are the same as those in the above-described embodiment, the description of these parts is omitted.

  FIG. 23 is a diagram illustrating the positions of the dot formation pixels of the nozzle # 1 for explaining the third embodiment. In FIG. 23, a pixel with a hatched circle indicates a dot formation pixel. In the present embodiment, the position of the pixel is represented as (X, P). Here, P represents a pass number for forming the dot formation pixel or the dot non-formation pixel. X represents the coordinate in the X direction of the pixel.

T _fl in the figure is the time from when the flushing operation is completed until the head reaches the position on the left outer side of the paper in pass 1 (pass start position). Further, T _init is the time until the head moves from the position on the left outer side of the paper to the position of X coordinate 1. t _p is the time required from the start of the path to the start of the next pass. t _p ′ is the time required from the start of the skip path to the start of the next path. Incidentally, t _p is the same as the time required from a certain position to the position of the same X-coordinate of the next pass. T ₁ is the moving time of the head from the position (1, P ₁ ) where the X coordinate is 1 to the first position (X ₁ , P ₁ ). T ₂ is the moving time of the head from X ₁ to X ₂ in the X coordinate. D _px indicates the distance between pixels.

  FIG. 22 is a flowchart of a non-ejection time calculation routine in the third embodiment. When the non-ejection time calculation routine is called, the CPU 113 searches for the position of the first dot formation pixel that appears (S2202). The search method is performed by examining whether or not dot formation pixel data exists in order from the left in raster data from pass 1 to pass n for each nozzle. Referring to FIG. 23, there is a dot formation pixel in the fifth pass 2. Therefore, (5, 2) is specified as the position of the first dot formation pixel.

  Next, the CPU 113 determines whether or not the first dot formation pixel exists (S2204). In (S2202) described above, (5, 2) is specified as the position of the first dot formation pixel, so the flow proceeds to S2206. When the first dot formation pixel does not exist, the flow proceeds to S2220.

  When the first dot formation pixel can be found, the CPU 113 calculates the non-ejection time from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel (S2206).

When the position of the first dot formation pixel and _{(X 1, P} 1), the position of the first dot formation pixels _{(X 1, P} 1) the head moving time until the _{T 1} from the start position of the path _{P 1,} The non-ejection time T _total 'from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel is:

_{T total '= T fl + T} init + (P 1 -1-N skp) t p + N skp · t p' + T 1 (3)

It becomes. Here, N _skp is the number of skip information set to 1 from the completion of the first flushing operation to the start of the path P ₁ .

The head moving time T ₁ from the start position of the pass P ₁ to (X ₁ , P ₁ ) is the moving speed V _c (m / s) in the X direction of the head, and the distance between pixels is D _px (M)

T ₁ = (X ₁ −1) · D _px / V _c (4)

It becomes. Here, the moving velocity V _c of the head is assumed to have a constant speed.

  When the non-ejection time from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel is obtained, the CPU 113 displays the non-ejection time table as shown in FIG. 20 as in the first embodiment. The obtained value is recorded (S2208).

  Next, the CPU 113 searches for and specifies the position of the next dot formation pixel (S2210). Referring to FIG. 23, for nozzle 1, there is a sixth dot formation pixel in pass 3. Therefore, (6, 3) is specified as the position of the next dot formation pixel.

  Next, the CPU 113 determines whether or not there is a next dot formation pixel (S2212). For the above-mentioned nozzle # 1, since (6, 3) is specified as the next dot formation pixel, the flow proceeds to S2214. On the other hand, when the next dot formation pixel is not found, this flow is finished.

  When the position of the next dot formation pixel is specified, the CPU 113 sets the previous second position as the first position, and sets the position of the dot formation pixel specified this time as the second position (S2214). However, this time is the execution of the first flow, and the second position is not set. Therefore, the position of the first dot formation pixel is set to the first position. For example, the position of the next dot formation pixel specified this time is (6, 3). Therefore, the CPU 113 sets the position (5, 2) of the first dot formation pixel as the first position, and sets the position (6, 3) of the next dot formation pixel as the second position.

Next, the CPU 113 calculates a non-ejection time from the first position to the second position (S2216). When the non-ejection time from the _first position (X ₁ , P ₁ ) to the second position (X ₂ , P ₂ ) is T _1to2 ′,

_{T 1to2 '= (P 2 -P} 1 -N skp) t p + N skp · t p' + T 2 (5)

It becomes.
Moreover, the movement time _{T 2} of the head from _{X 1} to _{X 2} is

T ₂ = (X ₂ −X ₁ ) · D _px / V _c (6)

It becomes.
The CPU 113 substitutes each value into the equations (5) and (6) to obtain the non-ejection time T _1to2 ′ from the first position to the second position (S2216).

Next, the CPU 113 _{records the calculated} T _1to2 ′ in the non-ejection time table together with the non-ejection period (S2218).

  Next, the flow returns to S2210. And the non-ejection time table of FIG. 20 is created by repeating the above-mentioned procedure. Finally, in S2212, no dot formation pixel can be found. At this point, this routine ends.

  By the way, when the first dot formation pixel is not found in the search in S2204, the CPU 113 records 0 (s) in the non-ejection time table (S2220). When the first dot formation pixel does not exist, this nozzle does not eject ink droplets even while one page of the paper S is printed. Then, since this nozzle does not perform image formation, it is not necessary to perform a flushing operation for this nozzle. Therefore, since it is not necessary to refer to the non-ejection time of this nozzle in order to determine when to perform the flushing operation, 0 (s) that does not affect the subsequent determination is recorded.

  In the third embodiment, the non-ejection time is the time from the completion of the flushing operation until the head reaches the position of the first dot formation pixel, or from the position of one dot formation pixel to the position of the next dot formation pixel. The head travel time is as follows. Therefore, the non-ejection time can be obtained more accurately, and the timing for performing the flushing operation can be determined more accurately.

=== Fourth Embodiment ===
FIG. 8 is a diagram for explaining each region when an image is printed on the paper S. FIG. A printable area 801 is provided within the range of the paper S, and an image is formed within this range. The medium S includes an upper end printing area where upper end printing is performed, a normal printing area where normal printing is performed, and a lower end printing area where lower end printing is performed. When an image is formed in these areas, the conveyance amount up to the next pass is different. Next, upper end printing and lower end printing will be described.

  FIG. 10 is an explanatory diagram of upper end printing and lower end printing. Although the number of nozzles arranged in the transport direction is originally 180, the number of nozzles is assumed to be 8 here for the sake of simplicity.

In top-end printing, when printing near the top end of a print image, the paper is transported with a transport amount that is smaller than the transport amount during normal printing. For example, in the transport operation performed between pass 1 and pass 2, between pass 2 and pass 3, and between pass 3 and pass 4, the paper is transported by the transport amount D. In the transport operation performed between pass 4 and pass 5, the paper is transported by a transport amount 2 · D. In the upper end printing, the nozzles that eject ink are not constant. For example, nozzle # 2 to # 4 in pass 1, nozzle # 2 in pass 2, nozzles # 2 to # 7 in pass 3, nozzles # 2 to # 5 in pass 4, ink from nozzles # 2 to # 8 in pass 5 Is discharged. Since normal printing is performed from pass 5 onward, the paper is transported by a transport amount of 7 · D, and ink is ejected from seven nozzles (nozzles # 2 to # 8). Thereby, a continuous raster line can be formed at the upper end portion of the printed image.
In the lower end printing, as in the upper end printing, when the vicinity of the lower end of the print image is printed, the paper is transported with a transport amount smaller than the transport amount during normal printing. Further, in the lower end printing, the nozzles for ejecting ink are not constant as in the upper end printing. Thereby, a continuous raster line can be formed at the lower end portion of the printed image.
An area where a raster line is formed only by normal printing is called a normal printing area. An area located on the upper end side (downstream in the transport direction) of the paper from the normal print area is referred to as an upper end print area, and an area located on the lower end side (upstream in the transport direction) of the normal print area is referred to as a lower end print area. Call.

By the way, in the third embodiment, it is assumed that the transport amount is constant, and the time t _p from a certain path to the next path and the time t _p ′ from a certain skip path to the next path are constant. I explained. However, the transport amount is small during upper end printing and lower end printing. Therefore, at the time of the upper end during printing and lower-end printing, itself _{'t p} and t _p from the transport time is shorter contained in _the' time t _p and t _p is shortened.
In the fourth embodiment, in consideration of the thus when the conveyance amount is different, the variable t _p and t _{p '.} Here, how to obtain the non-ejection time when t _p and t _p ′, which are different from the third embodiment, are made variable will be described.

In the fourth embodiment, the time from the completion of the flushing operation until the head reaches the position of the first dot formation pixel, or the movement time of the head from the position of one dot formation pixel to the position of the next dot formation pixel At the time of calculation, the carry amount information of the print data is referred to. The configured time t _p and t _{p 'is} variable for each path. Further, in the present embodiment, the time t _p from one path to the next _path, and the time t _{p 'from} the skip path corresponding to each conveyance amount information to the next path is predetermined corresponding to each conveyance amount information Stored in the memory 114.

The fourth embodiment differs in the non-ejection time calculation method in S2206 and S2216 of the third embodiment (FIG. 22). Here, S2206 and S2216 different from the third embodiment will be described.
In step S <b> 2206, the CPU 113 obtains a non-ejection time from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel. In the third embodiment, the non-ejection time T _total 'from when the first flushing operation is completed to when the head reaches the position of the first dot formation pixel is obtained using Expression (3). In the embodiment, the non-ejection time T _total 'is obtained using the following equation (3').

_{T total '= T fl + T} init + t p (p1-1) + ··· + t p (1) + T 1 (3')

(However, when the path corresponds to the skip path, tp _{(i) is set} to tp _(i) ')

Here, tp _(i) is the time required from the start of the path i to the start of the next path (i + 1). For example, tp _(p1-1) is the time required from the start of the path (P ₁ -1) to the start of the next path (P ₁ -2). Further, tp _(i) ′ is a transport time required from the start of the skip pass (i) to the start of the next pass (i + 1). tp _(i) and tp _(i) ′ are obtained by referring to the memory 114 from the carry amount information as described above. The carry amount information at the pass number i can be obtained by referring to the print data at the pass number i.

In step S2216, the CPU 113 calculates a non-ejection time from the _first position (X ₁ , P ₁ ) to the second position (X ₂ , P ₂ ). In the third embodiment, the non-ejection time T _1to2 ′ from the first position to the second position is obtained using the equation (5), but in the fourth embodiment, the following equation (5 ′) is obtained. To determine the non-ejection time T _1to2 ′.

T _1to2 ′ = tp _(p2-1) +... + _{Tp (p1)} + T ₂ (5 ′)

(However, when the path corresponds to the skip path, tp _{(i) is set} to tp _(i) ')

  In this way, even when the transport amount varies from pass to pass, the non-ejection time can be obtained accurately, so the timing for performing the flushing operation more accurately can be determined based on the non-ejection time. Can do.

=== Fifth Embodiment ===
FIG. 8 shows the BS control area so as to overlap the lower end printing area. The BS control is called brake control, and is a control for making the transport speed of the transport roller 23 slower than the normal transport speed. As described above, the BS control is performed in the printer 1 of the present embodiment for the following reason.

  FIG. 12 is a diagram for explaining the reason why the BS control is performed. The paper S is transported by the transport roller 23 and the driven roller 26. As shown in FIG. 12, the driven roller 26 is configured to press the paper S against the transport roller 23 by a spring 27 during the transport. Recently, it has been required to print up to the end of the paper S. For this purpose, it is necessary to press the end of the paper S with the transport roller 23 and the driven roller 26. However, since the driven roller 26 is configured to be pressed against the transport roller 23 by the spring 27, when the transport is performed so that the end of the paper S is located in the predetermined range, it is shown in FIG. Thus, a force F that causes the paper S to be sent out by the spring 27 acts on the paper S. For this reason, the paper S is sent out between the transport roller 23 and the driven roller 26, and the transport accuracy cannot be secured near the end of the paper S. Therefore, in the printer 1 according to the present embodiment, in order to ensure the conveyance accuracy even near the end of the paper S that is a medium, control is performed to reduce the conveyance speed near the end.

When performing such slowed the transport time becomes longer like controls the transport speed, because the transport time becomes longer contained from one path to the time t _p up to the next pass, also t _p itself become longer. In the fifth embodiment, the non-ejection time is obtained in consideration of the case where the conveyance time becomes long as described above. Here, a description will be given of determining the non-ejection time when t _p is different from the third embodiment becomes longer.

  FIG. 24 is a diagram illustrating an example of print data for explaining the fifth embodiment. In FIG. 24, 1 is recorded in the BS control information for the pass immediately before the transport operation for performing BS control. That is, BS control is performed to reduce the transport speed in the subsequent transport operation of the path whose BS control information is set to 1. For example, in FIG. 24, the BS control information for the path 98 is set to 1. Therefore, in the transport operation subsequent to the pass 98, BS control for decreasing the transport speed is performed. Here, for the sake of simplicity of explanation, the path 100 is the last path in the present embodiment. Although the BS control information also exists in the path 100 which is the final path, the BS control information for the path 100 is not actually used because the BS control is not necessary in the transport operation following the final path.

  As a BS control information setting method, in the fifth embodiment, the pass number immediately before the transport operation for performing the BS control is obtained based on the size of the paper S in the transport direction, and the BS control of the print data of this pass number is performed. 1 is written in the information. Then, for the transport operation that follows the pass of the print data in which 1 is written in the BS control information, the transport speed is controlled to be slower than the normal transport speed. The size of the paper S to be printed is stored in the memory 114 in advance.

In the fifth embodiment, when determining the non-ejection time, the BS control information of the print data is referred to. Moreover, definitive when BS control information is 0, the start of the path and time t _p up to the beginning of the next pass, the time t _{p 'and} the memory 114 is determined in advance from the skip path to the next path It is remembered. Moreover, definitive when BS control information is 1, the time from the start of the path up to the beginning of the next pass' and the time t _p from the skip path to the next path _{'t p'} '' and is determined in advance Stored in the memory 114.

  The fifth embodiment differs in the non-ejection time calculation method in S2206 and S2216 of the second embodiment. Here, S2206 and S2216 different from the second embodiment will be described.

In step S <b> 2206, the CPU 113 obtains a non-ejection time from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel. In the second embodiment, the non-ejection time T _total 'from the completion of the first flushing operation until the head reaches the position of the first dot formation pixel is obtained using the expression (3). In the embodiment, T _total ′ is obtained using the following equation (3 ″).

_{T total '= T fl + T} init + (P 1 -1-N skp' -N BS '-N skp &BS') · t p + N skp '· t p' + N BS · t p '' + N skp & BS '· t p '''+ T ₁ (3'')

Here, N _{skp & BS} is a number in which 1 is set for both the skip control information and the BS control information from the completion of the first flushing operation to the start of the path P ₁ . N _skp is the number of paths for which only skip information is set to 1 from the completion of the first flushing operation to the start of the path P ₁ . N _BS is the number of paths for which only BS control information is set to 1 from the completion of the first flushing operation to the start of path P ₁ .

In step S2216, the CPU 113 calculates a non-ejection time from the _first position (X ₁ , P ₁ ) to the second position (X ₂ , P ₂ ). In the third embodiment, the non-ejection time T _1to2 ′ from the first position to the second position is obtained using the equation (5). In the fifth embodiment, the following equation (5 ″) To determine the non-ejection time.

_{T 1to2 '= (P 1 -1} -N skp' -N BS '-N skp &BS') · t p + N skp '· t p' + N BS · t p '' + N skp & BS '· t p''' + T 2 (5 '')

  In this way, even when the transport speed is controlled to be slow, the non-ejection time can be obtained accurately, so it is possible to determine the timing for performing the flushing operation more accurately based on the non-ejection time. it can.

=== Sixth Embodiment ===
As described in the fifth embodiment, in order to ensure the conveyance accuracy even near the end of the paper S, the printer 1 performs control to reduce the conveyance speed near the end. As described above, if the flushing operation can be performed when the control is performed such that the transport time is delayed and the transport time is increased, a part of the flushing operation time can be incorporated into the long transport time. Printing time can be shortened. In the sixth embodiment, the flushing operation performed immediately before skip control in the first embodiment is performed during BS control.

  An embodiment in which a flushing operation is performed during BS control will be described. In the first embodiment, in S1508, the flushing operation is performed in the transport operation immediately before the pass whose skip information is 1. In the fifth embodiment, BS control information is referred instead of referring to the skip information of FIG. Then, a path closest to the specific path is searched for among the paths whose BS control information is 1 from the first path to the specific path.

  FIG. 25 shows the BS control information extracted in the non-ejection interval path. In FIG. 25, the path 87 is the first path, and the path 100 is the second path. That is, the non-ejection section is a pass 87 to a pass 100. Further, the specific path is a path 94. At this time, in the first embodiment, the flushing operation is performed in the transport operation immediately before the pass whose skip information is 1. Therefore, referring to FIG. 25, since the skip information of the path 91 is 1, 1 is set to the flushing information of the path 90. However, in the sixth embodiment, the flushing operation is performed during the transport operation subsequent to the path closest to the specific path among the paths whose BS control information existing from the first path to the specific path is 1. To do. That is, in the sixth embodiment, 1 is set in the flushing information of the path of the BS control closest to the specific path among the paths having the BS control information of 1 from the first path to the specific path. In FIG. 25, the path 93 whose BS control information is closest to the specific path among the paths 87 (first path) to 94 (specific path) is the path 93. Therefore, 1 is set in the flushing information of the path 93.

  By doing so, a part of the time of the flushing operation can be incorporated during the BS control with a long conveying time, so that the entire printing time can be shortened.

=== Other Embodiments ===
Although the printing system 100 as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

(1) In the above-described embodiment, the memory 114 of the host-side controller 111 stores print data. This print data includes raster data and command data for each pass. The printer-side controller 70 as a part of the control unit causes the head to perform an ejection operation for ejecting ink droplets from the nozzles based on the print data, prints an image on the paper S, and does not land on the paper S. In this way, the head is caused to perform a flushing operation for forcibly ejecting ink droplets. The host-side controller 111 as a part of the control unit determines the timing of performing the flushing operation from the start of printing an image on the paper S to the end of printing based on the print data stored in the memory 114. to decide.
With such a configuration, it is possible to determine the timing for performing the flushing operation and perform scheduling to shorten the printing time.
In the present embodiment, the timing for performing the flushing operation is determined to be performed when the conveyance time is long, but is not limited thereto. For example, the flushing operation may be performed when the time from the end of one pass to the start of the next pass becomes longer due to other reasons not shown in the present embodiment.

(2) For example, the printer-side controller 70 alternately repeats a path (ejection operation) for ejecting ink droplets from the nozzles and a conveyance operation for conveying the paper S. When the transport operation for a predetermined transport time and the transport operation for a transport time longer than the predetermined transport time are performed based on the print data, the host-side controller 111 determines that the transport time is long. A flushing operation is performed during the transport operation.
In this way, since the flushing operation can be performed during the conveyance operation for a long conveyance time, a part of the flushing operation time can be incorporated into the long conveyance operation time, and the printing time can be shortened. Can do.
However, the print data referred to when determining the location of the transport operation with a long transport time is not limited to the print data described in the present embodiment. For example, when print data is created, it is possible to comprehensively obtain data indicating the timing of the transport operation in which the transport time is increased by an algorithm prepared separately and add it to the print data. It is also possible to determine when to perform the flushing operation based on the print data.

(3) Further, in the printing system 100, the conveyance operation in the conveyance time longer than the conveyance operation in the predetermined conveyance time has a larger conveyance amount.
In this way, it is possible to determine that a transport operation with a large transport amount is a transport operation with a long transport time.

(4) Further, the host-side controller 111 as a part of the control unit obtains a non-ejection time that is a time during which the nozzles do not eject ink droplets based on the print data, and this non-ejection time exceeds the flushing limit time. It is determined that the flushing operation is to be performed before the transport operation for a long transport time.
In this way, since the flushing operation can be started before the flushing limit time is exceeded, it is possible to shorten the printing time while performing the flushing operation before thickening affects image formation.
However, the criterion for determining when to perform the flushing operation is not limited to the flushing limit time, and when a more appropriate predetermined time is obtained experimentally and empirically, the timing for performing the flushing operation based on this is used. Judgment can be made.

(5) Further, the host-side controller 111 as a part of the control unit may determine that ink droplets are not ejected from any nozzle in a certain pass based on the print data. At this time, the printer-side controller 70 as a part of the control unit omits the pass by performing a transport operation for a long transport time with the transport amount including the transport amount of the next transport operation in the transport operation before a certain pass. . Then, before the non-ejection time exceeds the flushing limit time, it is determined to perform the flushing operation when performing the transport operation for a long transport time with the transport amount including the transport amount of the next transport operation.
In this way, a flushing operation can be performed during a transport operation in which a pass is omitted and the transport time is long, so a part of the time of the flushing operation is incorporated into a part of the time of the long transport operation. Printing time can be shortened.

(6) Further, the host-side controller 111 as a part of the control unit determines to perform the flushing operation in the transport operation closest to the path reaching the flushing limit time.
By doing in this way, it is possible to perform the flushing operation in the transport operation in which the transport operation is performed with the transport amount including the transport amount of the next transport operation and the transport time becomes long, and as much as possible. A flushing operation can be performed at the rear end. If it does so, possibility that the frequency | count of flushing operation can be reduced becomes high, and printing time can be shortened as a result.

(7) Further, the host-side controller 111 determines to perform the flushing operation in the transport operation with the largest transport amount.
In this way, since the flushing operation can be performed in the conveyance operation with the largest conveyance amount, a part of the flushing operation time can be incorporated during the long conveyance time, and the printing time can be shortened. .

(8) In addition, the conveyance speed of the paper S is slower in the conveyance operation of the conveyance time longer than the conveyance operation of the predetermined conveyance time.
By doing in this way, it can be judged that it is a long conveyance time when the conveyance speed of the paper S is slow.

(9) In addition, the host-side controller 111 acquires BS control information related to slowing the transport speed in the transport operation of the paper S, and based on this BS control information, before the non-ejection time exceeds the flushing limit time Therefore, it is determined to perform the flushing operation when the transport speed is decreased.
In this way, the flushing operation can be performed when the conveyance speed is slow and the conveyance time is longer than that during normal printing. Therefore, a part of the flushing operation is incorporated into a part of the long conveyance time. Printing time can be shortened.
However, the information related to slowing the transport speed is not limited to the BS control information, and when there is other information for controlling the transport speed, it is possible to determine the timing for performing the flushing operation based on this information.

(10) The printing system 100 also includes a transport roller for transporting the paper S in the transport operation. Further, the printer-side controller 70 changes the transport speed of the paper S in the transport operation when the end on the upstream side in the transport direction of the paper S passes the transport roller.
In this way, when it is necessary to ensure the conveyance accuracy, it is possible to perform BS control that secures the conveyance speed by reducing the conveyance speed at the end of the paper S.
However, in this embodiment, the speed change is a two-step process for determining whether or not BS control is performed. However, continuous speed control can be performed such as transporting slower as the end is approached.

(11) When the host-side controller 111 determines that ink droplets are not ejected from any nozzle in a certain ejection operation based on the print data, the transport amount of the next transport operation in the transport operation before a certain pass The carry operation is performed with the carry amount including “Skip”, and skip control for omitting the pass is performed. In such a case, the host-side controller 111 acquires transport amount information related to the transport amount including the transport amount of the next transport operation, and obtains the non-ejection time based on the acquired transport amount information.
In this way, even when skip control for omitting a pass is performed, the non-ejection time can be obtained accurately, so that the timing for performing the flushing operation can be determined more accurately.

(12) The printer-side controller 70 prints the upper end or lower end in the transport direction of the paper S between the time when the ink droplet is ejected and the time when the next ink droplet is ejected. The transport operation is performed with a transport amount different from the transport amount of the transport operation performed during normal printing. In such a case, the host-side controller 111 acquires transport amount information regarding different transport amounts, and obtains a non-ejection time based on the transport amount information.
In this way, since the non-ejection time is obtained based on the carry amount information, the non-ejection time can be obtained accurately and the flushing operation is performed even when the carry amount varies depending on the printing region. It becomes possible to judge the time more accurately.
However, the information regarding the transport amount is not limited to the transport amount information, and when there is other information for controlling the transport amount, the non-ejection time can be obtained based on the information.

(13) Further, the host-side controller 111 acquires BS control information related to the conveyance speed in the conveyance operation of the paper S, and from ejecting an ink droplet to ejecting the next ink droplet based on this BS control information The non-ejection time when the transfer operation is performed during this period is obtained.
In this way, the non-ejection time can be obtained in consideration of the transport speed at the time of BS control for controlling the transport speed to be low in order to ensure the transport accuracy, and the timing for performing the flushing operation can be determined more accurately. be able to.
However, the information regarding the conveyance speed is not limited to the BS control information, and when there is other information for controlling the conveyance speed, the non-ejection time can be obtained based on the information.

(14) Further, the memory 114 of the host-side controller 111 as a storage unit of the printing system 100 in the present embodiment stores print data for one page of paper S1.
As described above, since the memory 114 stores the print data for one page, it is possible to determine when to perform the flushing operation in printing for one page.

(15) Further, according to the printing system including all the above-described components, the effects of the present invention can be achieved most effectively because almost all the effects described above can be obtained.

(16) Further, in the above-described embodiment, the printing for performing the flushing operation by determining the timing of the flushing operation from the start of printing the image on the paper S to the end of the printing based on the print data. It goes without saying that there is a method disclosure. According to such a printing method, it is possible to perform the flushing operation by determining when to perform the flushing operation based on the print data.

1 is a diagram for explaining a configuration of a printing system 100. FIG. 1 is a block diagram for explaining a configuration of a printing system 100. FIG. FIG. 3A is a schematic diagram of the overall configuration of the printer 1. FIG. 3B is a cross-sectional view illustrating the configuration of the printer 1. FIG. 4 is an explanatory diagram showing the arrangement of nozzles on the lower surface of a head 41. It is a flowchart of the process at the time of printing. It is a flowchart of a print data generation process. 7A, 7B, 7C, and 7D are explanatory diagrams of the flushing operation. FIG. 4 is a diagram for explaining each region when an image is printed on paper S. 9A and 9B are explanatory diagrams of interlaced printing. It is explanatory drawing of upper end printing and lower end printing. It is a figure for demonstrating the conveyance amount when skip control is performed. It is a figure for demonstrating the reason which is supposed to perform BS control. It is a figure showing the raster data in this embodiment. It is an example of print data in each pass. It is a flowchart of the judgment program of the time of flushing operation | movement. It is a figure for demonstrating calculation of non-ejection time. It is a flowchart of the non-ejection time calculation routine. It is a figure which shows an example of print data. The skip information in the non-ejection section path is extracted. It is a figure which shows an example of a non-ejection time table. It is a figure for demonstrating the process in S1506. It is a flowchart of the non-ejection time calculation routine in the third embodiment. It is a figure which shows the position of the dot formation pixel for demonstrating 3rd Embodiment. It is a figure which shows the example of the print data for demonstrating 5th Embodiment. The BS control information in the non-ejection section path is extracted.

Explanation of symbols

1 printer,
20 paper transport mechanism, 21 paper feed roller, 22 transport motor,
23 transport roller, 24 platen, 25 paper discharge roller, 26 driven roller,
30 Carriage moving mechanism, 31 Carriage motor, CR carriage,
40 head units, 41 heads,
60 detector groups, 61 linear encoder, 62 rotary encoder,
63 paper detector, 64 paper width detector,
70 printer side controller, 71 interface unit,
72 CPU, 73 memory, 74 control unit,
100 printing system, 110 computer, 111 host side controller,
120 display device, 130 input device, 140 recording / reproducing device

Claims (16)

A storage unit for storing print data;
Flushing that forcibly ejects the liquid droplets so as not to land on the medium, the control unit for causing the head to perform an ejection operation of ejecting liquid droplets from the nozzles based on the print data and printing an image on the medium A control unit for causing the head to perform an operation,
The control unit, based on the print data, determines a timing for performing the flushing operation between the start of printing the image on the medium and the end of printing. The printing system according to claim 1,
The control unit alternately repeats a discharge operation of discharging the liquid droplets from the nozzle and a transport operation of transporting the medium,
When a transport operation for a predetermined transport time and a transport operation for a transport time longer than the predetermined transport time are performed based on the print data, the flushing operation is performed during the transport operation for the long transport time. Printing system. The printing system according to claim 2,
A printing system in which the transport operation for the long transport time has a larger transport amount than the transport operation for the predetermined transport time. The printing system according to claim 3,
The control unit obtains a non-ejection time that is a time during which the nozzle does not eject the liquid droplets based on the print data, and before the non-ejection time exceeds a predetermined time, A printing system that determines to perform the flushing operation during a transport operation. The printing system according to claim 4,
When the controller determines that the liquid droplets are not ejected from any nozzle in a certain ejection operation based on the print data, the conveyance amount of the next transportation operation is included in the transportation operation before the certain ejection operation. Perform the transport operation for the long transport time with the transport amount to omit the discharge operation,
It is determined that the flushing operation is performed when the transport operation for the long transport time is performed with the transport amount including the transport amount of the next transport operation before the non-ejection time exceeds the predetermined time. A printing system. The printing system according to claim 5, wherein
The printing system, wherein the control unit determines to perform the flushing operation in a transport operation closest to the discharge operation up to the predetermined time. The printing system according to claim 5, wherein
The printing system, wherein the control unit determines to perform the flushing operation in a transport operation having the largest transport amount. The printing system according to claim 2,
The printing system in which the transport speed of the medium is slower in the transport operation of the longer transport time than the transport operation of the predetermined transport time. The printing system according to claim 8, comprising:
The control unit obtains information related to reducing the conveyance speed of the medium in the conveyance operation, and based on the information, before the non-ejection time exceeds the predetermined time, A printing system that determines to perform the flushing operation when it is delayed. The printing system according to claim 9,
The printing system includes a transport roller for transporting the medium in the transport operation,
The said control part is a printing system which changes the conveyance speed of the said medium in the said conveyance operation, when the edge part of the conveyance direction upstream of the said medium passes the said conveyance roller. The printing system according to claim 4,
When the controller determines that the liquid droplets are not ejected from any nozzle in a certain ejection operation based on the print data, the transport amount of the next transportation operation is determined in the transportation operation before the certain ejection operation. When performing the transport operation with a transport amount including and omitting the discharge operation,
The printing system which acquires the information regarding the conveyance amount containing the conveyance amount of the said next conveyance operation, and calculates | requires the said non-ejection time based on the acquired information. The printing system according to claim 4,
The transport is performed when the central portion of the medium is printed in order to print an end portion in the transport direction of the medium between the ejection of a liquid droplet and the ejection of the next liquid droplet. When performing the transport operation with a transport amount different from the transport amount of the operation,
The printing system which acquires the information regarding the said different conveyance amount, and calculates | requires the said non-ejection time based on the said information. The printing system according to claim 4,
The control unit acquires information related to the transport speed of the medium in the transport operation, and based on the information, the transport operation is performed after a liquid droplet is ejected until the next liquid droplet is ejected. A printing system for obtaining the non-ejection time in the case. A printing system according to claim 1,
The storage unit stores a print data for one page of the medium. A storage unit for storing print data for one page of the medium;
Flushing that forcibly ejects the liquid droplets so as not to land on the medium, the control unit for causing the head to perform an ejection operation of ejecting liquid droplets from the nozzles based on the print data and printing an image on the medium A control unit for causing the head to perform an operation,
In the printing system, the control unit determines when to perform the flushing operation from the start of printing the image on the medium to the end of printing based on the print data.
The control unit alternately repeats a discharge operation for discharging the liquid droplets from the nozzle and a transport operation for transporting the medium, and based on the print data, a transport operation for a predetermined transport time; When the transport operation with a transport time longer than the predetermined transport time is performed, the flushing operation is performed during the transport operation with the long transport time,
The conveyance operation of the long conveyance time is larger than the conveyance operation of the predetermined conveyance time,
The control unit obtains a non-ejection time that is a time during which the nozzle does not eject the liquid droplets based on the print data, and before the non-ejection time exceeds a predetermined time, Judging to perform the flushing operation during the transport operation,
When the controller determines that the liquid droplets are not ejected from any nozzle in a certain ejection operation based on the print data, the conveyance amount of the next transportation operation is included in the transportation operation before the certain ejection operation. The transport operation is performed with the transport amount for the long transport time, the discharge operation is omitted, and the transport amount including the transport amount of the next transport operation is before the non-discharge time exceeds the predetermined time. When performing the transport operation for the long transport time, it is determined to perform the flushing operation,
The control unit determines to perform the flushing operation in a transport operation closest to the discharge operation up to the predetermined time;
The control unit determines to perform the flushing operation in the transport operation with the largest transport amount,
The transport operation of the longer transport time is slower than the transport operation of the predetermined transport time, the transport speed of the medium is slower,
The control unit obtains information related to reducing the conveyance speed of the medium in the conveyance operation, and based on the information, before the non-ejection time exceeds the predetermined time, Judging to perform the flushing operation when slowing down,
The printing system includes a transport roller for transporting the medium in the transport operation, and the control unit performs the transport operation when an end on the upstream side of the transport direction of the medium passes through the transport roller. Changing the conveyance speed of the medium in
When the controller determines that the liquid droplets are not ejected from any nozzle in a certain ejection operation based on the print data, the transport amount of the next transportation operation is determined in the transportation operation before the certain ejection operation. When performing the transport operation with the transport amount including and omitting the discharge operation, obtain information on the transport amount including the transport amount of the next transport operation, obtain the non-ejection time based on the acquired information,
The transport is performed when the central portion of the medium is printed in order to print an end portion in the transport direction of the medium between the ejection of a liquid droplet and the ejection of the next liquid droplet. When performing the transport operation with a transport amount different from the transport amount of the operation, obtain information on the different transport amount, obtain the non-ejection time based on the information,
The control unit acquires information related to the transport speed of the medium in the transport operation, and based on the information, the transport operation is performed after a liquid droplet is ejected until the next liquid droplet is ejected. A printing system for obtaining the non-ejection time in the case. Storing print data;
Determining when to perform a flushing operation between the start of printing an image on a medium and the end of printing based on the print data;
Performing the flushing operation based on the determining step;
Including printing method.

Images