JP7680712B2 - Printing device and computer program - Google Patents

Description

This specification relates to a control device for a print execution unit that includes a print head having multiple nozzles and a transport unit that transports a print medium in a transport direction relative to the print head.

The printer disclosed in Patent Document 1, when printing using multiple pass processes, prints a portion of the area near the boundary of the band area printed in each pass process in two pass processes. This prevents banding from becoming noticeable near the boundary of the band area. This printer is equipped with a pressing member that presses the paper from the printing surface side, upstream of the multiple nozzles of the print head in the transport direction.

JP 2016-153182 A

This specification discloses a technology that suppresses defects caused by deformation of the print medium when printing with a print execution unit that has an opposing member (e.g., the pressing member described above) that can face the printing surface of the print medium.

The technology disclosed in this specification can be realized as the following application examples:

[Application Example 1] A printing device comprising a print execution unit and a control device, the print execution unit comprising a transport unit that transports a print medium in a transport direction, a print head having a plurality of nozzles that eject ink of a specific color, the plurality of nozzles being positioned at different positions in the transport direction, and ejecting ink onto the print medium to form dots on the print medium, and an opposing member that can face the printing surface of the print medium upstream of the plurality of nozzles of the print head in the transport direction, and the control device causes the print execution unit to execute partial printing that forms the dots by the print head and transporting the print medium by the transport unit multiple times, thereby generating a print image. a printing device in which the control device, when causing the print execution unit to print the print image, executes final opposing partial printing, which is the last partial printing executed in a state in which the print medium faces the opposing member, and before executing the final opposing partial printing, the control device transports the print medium a final opposing transport amount, and the control device controls the specific transport amount so that the opposing length of the print medium changes depending on the position of the end of the print medium in an orthogonal direction perpendicular to the transport direction and the position of the opposing member in the orthogonal direction, the opposing length being the length in the transport direction of the portion of the print medium that faces the opposing member when the final opposing partial printing is executed.

When the upstream end of the print medium in the transport direction is deformed along the orthogonal direction, a defect may occur in which the corners located at both ends of the upstream end in the orthogonal direction come into contact with the print head. The likelihood of the above defect occurring varies depending on the position of the orthogonal end of the print medium and the orthogonal position of the opposing member. Also, the longer the opposing length of the print medium, the farther the upstream end of the print medium is from the print head, making the above defect less likely to occur. According to the above configuration, the opposing length of the print medium is changed depending on the position of the orthogonal end of the print medium and the orthogonal position of the opposing member. As a result, for example, if the position of the orthogonal end of the print medium and the orthogonal position of the opposing member are in a positional relationship that makes the above defect more likely to occur, the opposing length of the print medium can be increased to suppress the above defect. Therefore, defects due to deformation of the print medium can be suppressed.

The technology disclosed in this specification can be realized in various forms, such as a printing device, a control method for a print execution unit, a printing method, a computer program for realizing the functions of these devices and methods, a recording medium on which the computer program is recorded, etc.

FIG. 2 is a block diagram showing the configuration of a printer 200 according to the embodiment. FIG. 2 is a diagram showing a schematic configuration of a printing mechanism 100. FIG. 1 is a perspective view of a paper tray 145 and a plurality of pressing members 146. FIG. 4 is a diagram showing an example of printing on a sheet M1. FIG. 4 is a diagram showing an example of printing on paper M2. 4 is a flowchart of a printing process. 13 is a flowchart of a print data output process. FIG. 4 is a diagram showing an example of a method for setting a reference position RP. FIG. 11 is a diagram showing another example of printing on paper M1. FIG. 11 is a diagram showing another example of printing on paper M2. 13A and 13B are diagrams showing another example of a method for setting the reference position RP.

A. First embodiment:
A-1: Configuration of Printer 200 Next, the embodiment will be described based on an example embodiment. Fig. 1 is a block diagram showing the configuration of a printer 200 according to the example embodiment.

The printer 200 includes, for example, a print mechanism 100 as a print execution unit, a CPU 210 as a control device, a non-volatile storage device 220 such as a hard disk drive, a volatile storage device 230 such as a RAM, an operation unit 260 such as a button or touch panel for acquiring operations by a user, a display unit 270 such as a liquid crystal display, and a communication unit 280. The communication unit 280 includes a wired or wireless interface for connecting to the network NW. The printer 200 is connected to an external device, for example, a user's terminal device 300, via the communication unit 280 so as to be able to communicate with the external device.

The volatile storage device 230 provides a buffer area 231 for temporarily storing various intermediate data generated when the CPU 210 performs processing. The non-volatile storage device 220 stores a computer program PG. In this embodiment, the computer program PG is a control program for controlling the printer 200. The computer program PG may be provided by being stored in the non-volatile storage device 220 when the printer 200 is shipped. Alternatively, the computer program PG may be provided in a form in which it is downloaded from a server, or in a form in which it is stored on a DVD-ROM or the like. The CPU 210 executes the computer program PG to perform, for example, a printing process described below. As a result, the CPU 210 controls the printing mechanism 100 to print an image on a printing medium (e.g., paper).

The printing mechanism 100 can form dots on the paper M using ink (droplets) of each of the colors cyan (C), magenta (M), yellow (Y), and black (K), thereby performing color printing. The printing mechanism 100 includes a print head 110, a head drive unit 120, a main scanning unit 130, and a transport unit 140.

Figure 2 is a diagram showing a schematic configuration of the printing mechanism 100. As shown in Figure 2, the main scanning unit 130 includes a carriage 133 and a sliding shaft 134. The carriage 133 carries the print head 110. The sliding shaft 134 holds the carriage 133 so that it can move back and forth along the main scanning direction (the X-axis direction in Figure 2). The main scanning unit 130 uses the power of a main scanning motor (not shown) to move the carriage 133 back and forth (also called scanning) along the sliding shaft 134. This achieves main scanning, which moves the print head 110 back and forth along the main scanning direction relative to the paper M.

The transport section 140 holds the paper M and transports the paper M in a transport direction AR (+Y direction in FIG. 2) that intersects with the main scanning direction. As shown in FIG. 2A, the transport section 140 includes an upstream roller pair 142, a downstream roller pair 141, a paper tray 145, and a plurality of pressing members 146. Hereinafter, the upstream side (-Y side) of the transport direction AR will also be referred to simply as the upstream side, and the downstream side (+Y side) of the transport direction AR will also be referred to simply as the downstream side.

The upstream roller pair 142 holds the paper M upstream (-Y side) of the print head 110, and the downstream roller pair 141 holds the paper M downstream (+Y side) of the print head 110. The paper platform 145 is located between the upstream roller pair 142 and the downstream roller pair 141, and is positioned opposite the nozzle forming surface 111 of the print head 110. The downstream roller pair 141 and the upstream roller pair 142 are driven by a transport motor (not shown), whereby the paper M is transported in the transport direction AR.

The head drive unit 120 (Figure 1) supplies a drive signal to the print head 110 to drive the print head 110 while the main scanning unit 130 is performing a main scan of the print head 110. In accordance with the drive signal, the print head 110 ejects ink onto the paper being transported by the transport unit 140 to form dots.

Figure 2 (B) shows the configuration of the print head 110 as viewed from the -Z side (the lower side in Figure 2). As shown in Figure 2 (B), the nozzle forming surface 111 of the print head 110 has a plurality of nozzle rows consisting of a plurality of nozzles, that is, the nozzle rows NC, NM, NY, and NK that eject the above-mentioned C, M, Y, and K inks. Each nozzle row includes a plurality of nozzles NZ aligned along the transport direction AR. The positions of the plurality of nozzles NZ in the transport direction AR (+Y direction) are different from each other, and aligned along the transport direction AR at a predetermined nozzle interval NT. The nozzle interval NT is the length in the transport direction AR between two nozzles NZ adjacent to each other in the transport direction AR among the plurality of nozzles NZ. Of the nozzles that constitute these nozzle rows, the nozzle NZ located on the most upstream side (-Y side) is also called the most upstream nozzle NZu. In addition, of these nozzles NZ, the nozzle NZ located on the most downstream side (+Y side) is called the most downstream nozzle NZd. The length in the transport direction AR from the most upstream nozzle NZu to the most downstream nozzle NZd, plus the nozzle spacing NT, is also called the nozzle length D. The nozzle length D is expressed in units of the number of nozzles included in each nozzle row. Note that in an actual product, of the multiple nozzles NZ, the nozzles NZ near both ends in the transport direction AR may not be used for printing, but in this embodiment, an example will be described in which printing is performed using all the nozzles NZ that make up the nozzle length D. The nozzles NZ used for printing in this embodiment are called usable nozzles.

The positions of the nozzle rows NC, NM, NY, and NK in the main scanning direction (X direction in FIG. 2B) are different from each other, and their positions in the transport direction AR (Y direction in FIG. 2B) overlap with each other. For example, in the example of FIG. 2B, the nozzle row NK is arranged in the +X direction of the nozzle row NY that ejects Y ink.

The transport section 140 will be further described with reference to FIG. 3. FIG. 3 is a perspective view of the paper tray 145 and multiple pressing members 146. FIG. 3(A) shows a state in which paper M is not being held, and FIG. 3(B) shows a state in which paper M is being held. The paper tray 145 includes multiple high support members HP, multiple low support members LP, and a flat plate BB.

The flat plate BB is a plate member that is approximately parallel to the main scanning direction (X direction) and the transport direction (+Y direction). The upstream end (-Y side) of the flat plate BB is located near the upstream roller pair 142. The downstream end (+Y side) of the flat plate BB is located near the downstream roller pair 141.

As shown in FIG. 3(A), multiple high support members HP and multiple low support members LP are arranged alternately along the X direction on flat plate BB. That is, each low support member LP is disposed between two high support members HP adjacent to that low support member. Each high support member HP and low support member LP is a rib extending along the Y direction. As shown in FIG. 2(A), the upstream end (-Y side) of each high support member HP is located at the upstream end of flat plate BB. The downstream end (+Y side) of each high support member HP is located at the center of flat plate BB in the Y direction. The positions of both ends of each low support member LP in the Y direction are the same as the positions of both ends of the high support member HP in the Y direction.

The multiple pressing members 146 are positioned on the +Z side of the multiple low support members LP. The X-direction positions of the multiple pressing members 146 are the same as the X-direction positions of the multiple low support members LP. In other words, the X-direction position of each pressing member 146 is located between the two high support members HP adjacent to that pressing member 146. The multiple pressing members 146 are plate members that are inclined so that they approach the low support members LP as they move in the +Y direction. The Y-direction positions of the multiple pressing members 146 are upstream (-Y side) of the print head 110 and downstream (+Y side) of the upstream roller pair 142.

As shown in FIG. 3B, when the paper M is transported, the multiple high support members HP and the multiple low support members LP face the surface Mb side opposite the printing surface and support the paper M from the surface Mb side. The multiple pressing members 146 face the printing surface Ma and press the paper M from the printing surface Ma side. In this way, the multiple high support members HP, the multiple low support members LP, and the multiple pressing members 146 hold the paper M in a state in which it is deformed into a wavy shape along the X direction (FIG. 3B). Then, the paper M is transported in the transport direction (+Y direction) in a wavy shape at a position facing the nozzle forming surface 111 of the print head 110. By deforming the paper M into a wavy shape, the rigidity of the paper M against deformation along the Y direction can be increased. As a result, the paper M is deformed so as to be warped along the Y direction (transport direction), and it is possible to prevent the paper M from floating up from the paper base 145 toward the print head 110 side or the paper M from sagging toward the paper base 145 side. Such deformation of the paper M is also called deformation in the transport direction.

When deformation of the paper M occurs in the transport direction, the position at which dots are formed may shift, causing a deterioration in the quality of the printed image, for example, deterioration in image quality due to banding. Furthermore, when the upstream end Ed (FIG. 2A) of the paper M is lifted due to deformation in the transport direction, the upstream end Ed of the paper M may come into contact with the print head 110, causing the paper M to become soiled. As shown in FIG. 2A, in a state in which the upstream side (-Y side) of the paper M is not held by the pressing member 146 and only the downstream side (+Y side) of the paper M is held by the downstream roller pair 141 (also called a one-sided holding state), paper soiling due to deformation in the transport direction is likely to occur.

Here, in the one-sided holding state, the length from the position Yd in the Y direction where the paper M is held by the downstream roller pair 141 to the upstream end Ed of the paper M is also referred to as the one-sided paper length Ly. In the one-sided holding state, the longer the one-sided paper length Ly, the more likely it is that the upstream end of the paper M will approach the print head 110, and therefore the longer the one-sided paper length Ly, the more likely it is that paper stains will occur due to deformation in the transport direction.

Here, the manner in which the paper M is held by the multiple pressing members 146 and the support members HP, LP varies depending on the length of the paper M in the main scanning direction. FIG. 4 is an explanatory diagram of printing on paper M1 in the first embodiment. FIG. 4 shows the positions SP (hereinafter also referred to as specific positions SP) of the multiple pressing members 146 during partial printing at head position P3, which will be described later. The length Lx of the paper M1 in the main scanning direction (X direction) is approximately equal to the distance between the pressing member 146l (FIG. 3) located at the end in the -X direction and the pressing member 146r (FIG. 3) located at the end in the +X direction. For this reason, when paper M1 is used, all of the multiple pressing members 146 (six in the example of FIG. 3) face the paper M1 during printing, that is, they function as opposing members. Therefore, as shown at specific positions SPl and SPr in FIG. 4, during printing, the -X direction end Exl of the paper M1 is pressed by the pressing member 146l, and the +X direction end Exr of the paper M1 is pressed by the pressing member 146r.

Figure 5 is an explanatory diagram of printing on paper M2 in the first embodiment. In FIG. 5, as in FIG. 4, specific positions SP of the multiple pressing members 146 during partial printing at head position P3, which will be described later, are shown. The length L2 of paper M2 in the main scanning direction (X direction) is slightly shorter than the length Lx of paper M1 in the main scanning direction (X direction). The pressing member 146l located at the end in the -X direction and the pressing member 146r located at the end in the +X direction do not face paper M2 during printing. In other words, when paper M2 is used, of the multiple pressing members 146 (six in the example of FIG. 3), only four pressing members 146, excluding the two pressing members 146l and 146 at both ends, function as opposing members during printing. Therefore, as shown in the specific positions SPl and SPr in FIG. 5, the end Exl in the -X direction and the end Exr in the +X direction of paper M2 are not pressed by the pressing members 146l and 146r during printing.

For this reason, when paper M1 is used, the distance ΔLx (also called the non-pressing length ΔLx) between both ends Exl, Exr of paper M1 in the X direction and the opposing member (the member of the pressing member 146 that faces the paper) is 0 (Figure 4). On the other hand, when paper M2 is used, the non-pressing length ΔLx is a value greater than 0 (Figure 5). For this reason, when paper M2 is used, compared to when paper M1 is used, when the paper is held by the pressing member 146 and the support members HP, LP, the paper is more likely to deform along the X direction (main scanning direction) so that both ends Exl, Exr in the X direction face upward (+Z direction). This type of deformation is also called the main scanning direction deformation of paper M.

When deformation in the main scanning direction occurs in the paper M, the corners Cl and Cr (FIGS. 4 and 5) of the upstream end Ed of the paper M are likely to lift up. When the upstream corners Cl and Cr of the paper M lift up due to deformation in the main scanning direction, the upstream corners Cl and Cr of the paper M may come into contact with the print head 110, causing the paper M to become dirty. In addition, in a one-sided holding state in which the upstream side (-Y side) of the paper M is not held by the pressing member 146, the paper M does not deform in a wavy shape along the main scanning direction, so paper stains due to deformation in the main scanning direction of the paper M are less likely to occur. In this embodiment, paper stains due to deformation in the main scanning direction become a problem when the upstream side (-Y side) of the paper M is held by the pressing member 146 and the downstream side (+Y side) of the paper M is also held by the downstream roller pair 141 (also called a two-sided holding state).

Here, in the double-sided holding state, the distance ΔLy in the Y direction from the print head 110 to the upstream end Ed of the paper M is called the head separation length ΔLy. Figures 4 and 5 show the head separation length ΔLy at head position P3, which will be described later. The shorter the head separation length ΔLy, the closer the upstream angles Cl and Cr of the paper M are to the print head 110, making it more likely that paper stains will occur due to deformation in the main scanning direction.

The likelihood of paper stains occurring due to deformation in the main scanning direction and deformation in the transport direction differs depending on the deformation characteristics of paper M (e.g., ease of deformation of paper M). The deformation characteristics of paper M vary depending on the material and thickness of paper M, so the likelihood of paper stains occurring due to deformation in the main scanning direction and deformation in the transport direction differs depending on the material and thickness of paper M. As can be seen from the above explanation, the likelihood of paper stains occurring due to deformation in the main scanning direction and deformation in the Y direction differs between a first type of paper (e.g., paper M1) and a second type of paper (e.g., paper M2) that differs from the first type of paper in at least one characteristic (e.g., material, thickness, size in the main scanning direction, etc.).

In this embodiment, as described below, measures have been taken to appropriately suppress paper stains caused by deformation in the transport direction and paper stains caused by deformation in the main scanning direction.

A-2. Printing Process The CPU 210 (FIG. 1) of the printer 200 executes printing process based on a printing instruction input by a user via the operation unit 260. The printing instruction includes a specification of image data showing an image to be printed. The printing instruction also includes a specification of the type of paper M to be used for printing.

6 is a flowchart of the printing process. In S100, the CPU 210 identifies the type of paper M to be used for printing. The paper M assumed in this embodiment is paper (so-called cut paper) that has been cut to a predetermined size (length in the main scanning direction and the transport direction) defined by standards, etc. For example, the CPU 210 identifies the type of paper M to be used for printing by acquiring information indicating the type of paper M included in the print instruction. The information indicating the type of paper M includes, for example, information indicating the size of the paper M (A4, B4, legal, letter, etc.) and information indicating the paper type related to the material and thickness of the paper M (plain paper, fine paper, coated paper, etc.). The type of paper M may be identified, for example, by providing a sensor in the print mechanism 100 that detects the size and type of paper, based on the detection results of the sensor.

In S105, the CPU 210 determines a pressing reference position RP according to the type of paper M to be used for printing. The pressing reference position RP is used in the print data output process in S140. The pressing reference position RP is a position in the transport direction AR determined on the paper M. The pressing reference position RP is determined in advance for each type of paper M, and information indicating the pressing reference position RP is associated with the type of paper M and pre-integrated into the computer program PG. FIG. 4 illustrates the pressing reference position RP1 for paper M1. FIG. 5 illustrates the pressing reference position RP2 for paper M2. FIG. 5 also illustrates the pressing reference position RP1 for paper M1. As shown in FIG. 5, it can be seen that the pressing reference position RP1 and the pressing reference position RP2 differ by ΔS.

In S110, the CPU 210 acquires the image data specified by the print instruction from the non-volatile storage device 220. Alternatively, the print instruction and image data may be acquired from the terminal device 300. The acquired image data may be image data having various formats, such as JPEG compressed image data or image data described in a page description language.

In S120, the CPU 210 performs a rasterization process on the acquired image data to generate RGB image data. This results in the acquisition of RGB image data as the target image data in this embodiment. The RGB image data is bitmap data that contains RGB values for each pixel. The RGB values are color values in the RGB color system that contain, for example, the three component values of red (R), green (G), and blue (B).

In S130, the CPU 210 converts the RGB image data into print data. Specifically, the CPU 210 performs color conversion processing and halftone processing on the RGB image data. The color conversion processing is a process of converting the RGB values of multiple pixels contained in the RGB image data into CMYK values. The CMYK values are color values of the CMYK color system including component values (in this embodiment, the component values of C, M, Y, and K) corresponding to the inks used in printing. The color conversion processing is performed, for example, by referring to a known lookup table that specifies the correspondence between the RGB values and the CMYK values. The halftone processing is a process of converting the color-converted image data into print data (also called dot data). The print data is data that represents the dot formation state for each pixel for each color component of CMYK. The value of each pixel of the dot data indicates, for example, two gradations of "no dot" and "dot", or four gradations of "no dot", "small", "medium", and "large". Halftoning is performed using well-known techniques such as dithering and error diffusion.

In S140, the CPU 210 executes the print data output process. The print data output process is a process in which partial print data is generated for each partial print, which will be described later, and various control data is added to the partial print data and output to the printing mechanism 100. The control data includes data that specifies the transport amount TL of the sheet transport to be performed before partial printing. In the print data output process, the partial print data is output the same number of times as the number of partial prints to be performed. The print data output process will be described in detail later.

This allows the CPU 210 to cause the printing mechanism 100 to print the print image PI. Specifically, the CPU 210 controls the head drive unit 120, the main scanning unit 130, and the transport unit 140 to perform partial printing and sheet transport multiple times in an alternating manner, thereby performing printing. In one partial printing, with the paper M stopped on the paper tray 145, one main scan is performed while ejecting ink from the nozzles NZ of the print head 110 onto the paper M, thereby printing a portion of the print image on the paper M. In one sheet transport, the paper M is transported in the transport direction AR by a transport amount TL determined in the print data output process.

The print images PI in Figures 4 and 5 each include multiple raster lines RL that extend in the X direction (the main scanning direction during printing) in Figure 5 and have different positions in the Y direction (the transport direction AR during printing). Each raster line RL is a line on which multiple dots can be formed.

Figure 4 also shows head positions P0 to P3, i.e., the relative position of the print head 110 in the transport direction with respect to the paper M. Head positions P0 to P3 are the head positions for the last four partial prints out of the multiple partial prints. Figure 4 shows three sheet transports T0 to T2 with arrows. For example, sheet transport T0 is a sheet transport that is performed after partial printing performed at head position P0. Sheet transports T1 and T2 are sheet transports that are performed after partial printing performed at head positions P1 and P2, respectively.

Figure 5 shows head positions P0 to P4. Head positions P0 to P4 are the head positions for the last five partial prints out of multiple partial prints. In this way, when paper M2 is used ( Figure 5 ), there is one more partial print compared to when paper M1 is used ( Figure 4 ). In Figure 5 , the four sheet transports T0 to T3 are shown with arrows.

The hatched range of the head positions in Figures 4 and 5 is the range in which the nozzles NZ (also called used nozzles) used for printing in partial printing performed at that head position are located. The used nozzles are all or some of the available nozzles (all nozzles for the nozzle length D in this embodiment). In the example of Figures 4 and 5, all available nozzles are used in partial printing performed at head positions P0 to P2. In partial printing performed at head position P3, only some of the nozzles NZ on the upstream side (-Y side) are used, and some of the nozzles NZ on the downstream side (+Y side) are not used. In the example of Figure 5, in partial printing performed at head position P4, only some of the nozzles NZ on the downstream side (+Y side) are used, and some of the nozzles NZ on the upstream side (-Y side) are not used.

The print image PI formed on the paper M includes multiple partial areas. For example, the print image PI1 in FIG. 4 includes partial areas NA0 to N3. The print image PI2 in FIG. 5 includes partial areas NA0 to NA4. In each partial area, each raster line RL within the area is printed by only one partial printing. For example, in each raster line RL of partial area NA1 in FIGS. 4 and 5, dots are formed by partial printing performed at head position P1.

In this embodiment, in order to print while the paper M is held down by the pressing member 146 as much as possible, the last partial printing or the penultimate partial printing is performed while the specific position SP near the upstream end of the paper M is held down by the pressing member 146. In the example of FIG. 4, the last partial printing (partial printing performed at head position P3) is performed while the specific position SP is held down by the pressing member 146. In the example of FIG. 5, the penultimate partial printing (partial printing performed at head position P3) is performed while the specific position SP is held down by the pressing member 146, and the last partial printing (partial printing performed at head position P4) is performed in a one-sided holding state. Hereinafter, the head position P3 where the pressing member 146 holds down the specific position SP of the paper M is also referred to as the end pressing head position.

A-3. Print Data Output Processing Next, the print data output processing of S140 in Fig. 6 will be described. As described above, the print data output processing is a process in which partial print data is generated for each partial print using the print data generated in S130, various control data is added to the partial print data, and the partial print data is output to the printing mechanism 100. Fig. 7 is a flowchart of the print data output processing.

The print data generated in S130 in FIG. 6 represents the print image PI (FIGS. 4 and 5) to be printed. Therefore, the print data includes multiple raster data corresponding to the multiple raster lines RL included in the print image PI.

In S200, the CPU 210 acquires raster data corresponding to one raster line of interest (hereinafter also referred to as the "target raster data") from among the multiple raster data. The target raster lines are selected one by one from the multiple raster lines RL that are included in the print image PI and aligned in the transport direction AR, in sequence from the downstream side of the transport direction AR during printing (for example, the +Y side in Figures 4 and 5).

Here, partial printing of the raster line of interest is also called partial printing of interest. For example, if raster line RL1 in Figures 4 and 5 is the raster line of interest, partial printing of interest is partial printing performed at head position P0. If raster line RL2 is the raster line of interest, partial printing of interest is partial printing performed at head position P1. The nozzle NZ used to form dots on the raster line of interest in partial printing of interest is also called the nozzle of interest. For example, if the raster line RL processed first, that is, the raster line RL located at the most downstream of the print image PI, is the raster line of interest, the nozzle of interest is the nozzle NZ located at the most downstream of the usable nozzles.

In S210, the CPU 210 assigns the target raster data to the target nozzle.

In S220, the CPU 210 updates the number indicating the nozzle of interest. That is, the CPU 210 changes the number indicating the nozzle of interest to the number of the nozzle NZ that is one nozzle upstream from the current nozzle of interest.

In S230, the CPU 210 determines whether raster data has been assigned to all of the active nozzles in printing the target portion. Specifically, if the updated number indicating the target nozzle exceeds the number of the most upstream nozzle among the active nozzles, it is determined that raster data has been assigned to all of the active nozzles. If there is an active nozzle to which raster data has not been assigned (S230: NO), the process returns to S200.

If raster data has been assigned to all the nozzles in use (S230: YES), in S235, the CPU 210 outputs the partial print data for printing the target portion and the transport amount data to the printing mechanism 100. The partial print data is a group of raster data assigned to the nozzles in use. The transport amount data is control data indicating the transport amount TL. If the target portion printing is the first partial printing, the transport amount TL is determined so that the position on the paper M where the downstream end of the print image PI should be printed coincides with the position of the downstream end nozzle NZ among the nozzles in use. If the target portion printing is the second partial printing, the transport amount TL is the length of the number of nozzles in the usable nozzles, that is, the nozzle length D. This transport amount is determined in advance on the premise that the head position of the second partial printing will not be the end pressing head position. If the target portion printing is the third or subsequent partial printing, the transport amount TL is determined in S280, which will be described later. When the printing mechanism 100 receives the partial print data and the transport amount data, it transports the sheet by the transport amount TL indicated by the transport amount data, and then performs partial printing using the partial print data.

In S240, the CPU 210 determines whether all partial print data has been output. If all partial print data has been output (S240: YES), the CPU 210 ends the print data output process. If not all partial print data has been output (S240: NO), the CPU 210 updates the target portion printing in S245. That is, the target portion printing is set to the target portion printing next to the current target portion printing. Specifically, the initial value of the target nozzle for the next target portion printing is set to the new target nozzle number. The initial value of the corresponding nozzle for the next target portion printing has already been determined in S285 described below.

In S250, the CPU 210 determines whether the target portion printing is the final opposing portion printing. Final opposing portion printing is the last portion printing performed while the paper M is facing the pressing member 146, and specifically, is partial printing performed at the end pressing head position (head position P3 in Figures 4 and 5). If the target portion printing is not the final opposing portion printing (S250: NO), the process proceeds to S260.

In S260, the CPU 210 calculates the excess amount VO of the pressing reference position RP in printing the target portion. The excess amount VO indicates the length from the pressing reference position RP to the most upstream nozzle NZ among the usable nozzles in the head position in printing the target portion when the most upstream nozzle NZ is located upstream of the pressing reference position RP. The pressing reference position RP (FIGS. 4 and 5) is a position in the transport direction AR defined on the paper M as described above, and has been determined in S105 of FIG. 6. When the most upstream nozzle NZ in printing the target portion is located upstream of the pressing reference position RP, the next partial printing after printing the target portion is the final opposing partial printing, which is performed at the end pressing head position (head position P3 in FIG. 4 and FIG. 5).

In the examples of Figures 4 and 5, when the partial printing performed at head position P2 is the target portion printing, the upstream-most nozzle NZ at head position P2 is located upstream of the holding reference position RP, so an excess amount VO greater than 0 is calculated, as shown in Figures 4 and 5. In other words, when the partial printing following the target portion printing is the final opposing partial printing, an excess amount VO greater than 0 is calculated. The unit of the excess amount VO is, for example, indicated by the number of nozzles (number of raster lines).

When the most upstream nozzle is located at the same position as the holding reference position RP or downstream of the holding reference position RP, the excess amount VO is 0. In the example of Figures 4 and 5, when the partial printing performed at head positions P0 and P1 is the target partial printing, the most upstream nozzle at head positions P0 and P1 is located downstream of the holding reference position RP, so the excess amount VO is 0.

In S265, the CPU 210 sets the nozzle shift amount NS to the excess amount VO. The nozzle shift amount NS indicates the number of nozzles NZ (also called downstream unused nozzles) that are not used downstream among the available nozzles in the partial printing following the printing of the target portion. When the nozzle shift amount NS is 0, no downstream unused nozzles are provided. When the nozzle shift amount NS is 1 or more, the nozzles NZ of the available nozzles on the downstream side (the +Y side in Figures 4 and 5) that correspond to the nozzle shift amount NS are downstream unused nozzles. Therefore, in this case, the available nozzles excluding the downstream unused nozzles are the nozzles to be used in the partial printing following the printing of the target portion.

If the target portion printing is the final opposing portion printing (S250: YES), in S270, the CPU 210 sets the nozzle shift amount NS to 0. If the target portion printing is the final opposing portion printing and the next portion printing is performed, the next portion printing will be the last portion printing (Figure 5). In the last portion printing, the nozzle shift amount NS is set to 0 so that no unused nozzles are set downstream of the usable nozzles.

In S280, the CPU 210 determines the transport amount TL of the sheet transport performed after printing the target portion based on the nozzle shift amount NS. The transport amount TL is calculated in units of the number of nozzles. The transport amount is a value obtained by subtracting the nozzle shift amount NS from the number of usable nozzles. In this embodiment, the number of usable nozzles is the nozzle length D, so the transport amount TL is (D-NS). As a result, as shown in Figures 4 and 5, the transport amount TL of the sheet transport immediately before the final opposing portion printing (sheet transport T2 in Figures 4 and 5) is adjusted to an amount smaller than the nozzle length D, so that when the final opposing portion printing is performed, the paper M is transported so that the print head 110 is located at the end holding head position. Then, the transport amount TL of the sheet transport (sheet transports T0, T1, and T3 in Figures 4 and 5) excluding the sheet transport immediately before the final opposing portion printing is determined to be the nozzle length D. Here, the transport amount TL of the sheet transport T2 immediately before printing the final opposing portion is also called the specific transport amount.

In S285, the CPU 210 sets the number of the nozzle of interest for the partial printing next to the partial printing of the target portion to an initial value. The initial value is the number of the nozzle located upstream from the downstream end of the available nozzles by the nozzle shift amount NS. If the partial printing next to the partial printing of the target portion is the final opposing partial printing (for example, partial printing at head position P3 in Figures 4 and 5), the nozzle shift amount NS is greater than 0. Therefore, in this case, the initial value is the number of the nozzle NZ that is upstream of the downstream end nozzle NZ of the available nozzles. If the partial printing next to the partial printing of the target portion is a partial printing different from the final opposing partial printing, the nozzle shift amount NS is 0. Therefore, in this case, the initial value is the downstream end nozzle NZ of the available nozzles.

After S285, the CPU 210 returns the process to S200.

By carrying out the above print data output process, the edge pressing head position (head position P3 in Figs. 4 and 5) is determined so that the downstream end nozzle NZ of the available nozzles is located one raster line RL upstream (-Y side) from the pressing reference position RP (Figs. 4 and 5). For example, the pressing reference position RP2 (Fig. 5) when paper M2 is used is set ΔS downstream from the pressing reference position RP1 (Fig. 4) when paper M1 is used. For this reason, the edge pressing head position (head position P3 in Fig. 5) when paper M2 is used is located ΔS downstream from the edge pressing head position (head position P3 in Fig. 4) when paper M1 is used.

When paper M1 is used, the upstream edge of print image PI1 can be printed in the final opposing partial printing (Figure 4). When paper M2 is used, a portion including the upstream edge of print image PI2 cannot be printed in the final opposing partial printing. For this reason, when paper M2 is used, after the final opposing partial printing, the final partial printing is performed at head position P4, which is in a one-sided holding state (Figure 5).

The positional relationship in the transport direction between the print head 110 and the pressing member 146 is physically fixed. For this reason, when the end pressing head position is different, the opposing length of the paper M is also different. Here, the opposing length of the paper M is the length in the transport direction of the portion of the paper M that faces the pressing member 146 at the end pressing head position. Specifically, in this embodiment, the opposing length d2 when paper M2 is used is longer by ΔS than the opposing length d1 when paper M1 is used.

In this embodiment, in order to appropriately suppress the above-mentioned paper stains caused by the deformation in the transport direction and the deformation in the main scanning direction, an appropriate pressing reference position RP is set for each type of paper M, thereby setting an appropriate opposing length for each type of paper M. The method for setting the pressing reference position RP is described below.

Figure 8 is an explanatory diagram of a method for setting the pressing reference position RP in the first embodiment. Figure 8 (A) is a graph showing the relationship between the pressing reference position RP and the probability of a malfunction when paper M1 is used. Figure 8 (B) is a graph showing the relationship between the pressing reference position RP and the probability of a malfunction when paper M2 is used.

The vertical axis of the graph is the probability of a defect. The probability of a defect considered is the probability R1 that paper stains will occur due to deformation in the transport direction in the last partial print, the probability R2 that paper stains will occur due to deformation in the main scanning direction in the last partial print, and the probability R3 that paper stains will occur due to deformation in the main scanning direction in the penultimate partial print. Because the penultimate partial print is always performed in a double-sided holding state, the probability of transport direction deformation occurring in the penultimate partial print is considered to always be 0, and therefore this probability is not considered.

The horizontal axis of the graph is the distance H from the bottom edge of the paper to the pressing reference position RP. When a pressing reference position RP with distance H of A (left end of the graph) is adopted, the end pressing head position is set so that the opposing length is at the lower limit d1 (Figure 4). The lower limit d1 of the opposing length is at least the length necessary to reliably press the upstream edge of the paper M with the pressing member 146, and is determined taking into account the transport error of the paper M. The pressing reference position RP is not set so that the distance H is greater than (A + D) (D is the nozzle length D).

When the distance H is A (H=A), the upstream end of the print image PI can be printed at the end pressing head position (e.g., head position P3 in Figure 4) (Figure 4). For this reason, in this case, the final opposing partial printing at the end pressing head position becomes the last partial printing, and partial printing in a one-sided holding state is not performed. For this reason, when the pressing reference position RP is set to a position where the distance H is A, the probability R1 that paper stains will occur due to deformation in the transport direction during the last partial printing is 0.

When the distance H is greater than A (H>A), the upstream end of the print image PI cannot be printed in the final opposing partial printing at the end pressing head position (head position P3 in FIG. 5) (FIG. 5). For this reason, in this case, partial printing in the one-sided holding state is performed as the final partial printing, so the probability R1 of paper staining due to conveying direction deformation occurring in the final partial printing is greater than 0. In the one-sided holding state, as described above, the longer the one-sided holding paper length Ly, the higher the probability R1 of paper staining due to conveying direction deformation occurring. And, the farther the pressing reference position RP is from the upstream end of the paper M, the more the end pressing head position shifts downstream, so the head separation length ΔLy in the final partial printing becomes longer. Therefore, the probability R1 of paper staining occurring due to conveying direction deformation increases as the distance H increases (A<H<B range in the graph). However, when the distance H becomes greater than B, the upstream edge of the paper M begins to be pressed by the pressing member 146 during the final partial printing, and the probability R1 of paper staining due to the deformation of the transport direction gradually decreases to 0 (the range B<H<(A+D) on the graph). Note that the probability R1 of paper staining due to the deformation of the transport direction is the same for both paper M1 and paper M2.

When paper M1 is used, as shown in FIG. 4, in the double-sided holding state, the X-direction ends Exl and Exr of paper M1 are pressed by the pressing member 146. Also, in the single-sided holding state, as described above, paper staining caused by deformation in the main scanning direction is not an issue. For this reason, when paper M1 is used, deformation in the main scanning direction is unlikely to occur in either the double-sided holding state or the single-sided holding state. For this reason, when paper M1 is used, the probabilities R2 and R3 of paper staining caused by deformation in the main scanning direction are 0 (FIG. 8 (A)).

For this reason, when paper M1 is used, the distance H is determined to be A so that the probability R1 of paper staining due to deformation in the transport direction is minimized, as shown in FIG. 8(A). In other words, when paper M1 is used, the pressing reference position RP1 is set to a position that is the distance A away from the upstream edge of paper M1 (FIG. 4).

When paper M2 is used, as shown in FIG. 5, in the double-sided holding state, the X-direction ends Exl and Exr of paper M2 are not pressed by the pressing member 146. For this reason, when paper M2 is used, in the double-sided holding state, paper stains due to deformation in the main scanning direction may occur. Even when paper M2 is used, in the single-sided holding state, as described above, paper stains due to deformation in the main scanning direction are not a problem.

When deformation in the main scanning direction occurs in the both-end holding state, the upstream angles Cl and Cr of the paper M2 come into contact with the print head 110, causing paper staining. For this reason, in the both-end holding state, the probability of paper staining occurring due to deformation in the main scanning direction increases as the upstream angles Cl and Cr of the paper M2 are closer to the print head 110. When the distance H is A, as described above, partial printing at the end holding head position is the last partial printing. In this case, the upstream angles Cl and Cr of the paper M2 are closest to the print head 110 in the both-end holding state. For this reason, when the distance H is A, the probability R2 of paper staining occurring due to deformation in the main scanning direction in the last partial printing is maximum (Figure 8 (B)). When the distance H is greater than A, it is necessary to perform the last partial printing in the one-side holding state after partial printing at the end holding head position. In the one-sided holding state, paper stains caused by deformation in the main scanning direction are not a problem, so when distance H becomes greater than A, the probability R2 of paper stains occurring due to deformation in the main scanning direction in the final partial print becomes 0 (range A<H<B on the graph). Then, when distance H becomes greater than B, the upstream edge of paper M2 begins to be pressed by pressing member 146 in the final partial print, and deformation in the main scanning direction begins to occur, so the probability R2 of paper stains occurring due to deformation in the main scanning direction in the final partial print gradually increases (range B<H<(A+D) on the graph).

When the distance H is A, the last partial print is the final opposing partial print at the edge holding head position, so the penultimate partial print is performed with the upstream corners Cl and Clr of the paper M2 sufficiently far away from the print head 110. For this reason, when the distance H is A, the probability R3 that paper stains will occur due to deformation in the main scanning direction in the penultimate partial print is 0.

When the distance H is greater than A (H>A), the last partial printing is performed in a one-sided holding state, so the penultimate partial printing is the final opposing partial printing at the end holding head position (for example, FIG. 5). For this reason, when the distance H is greater than A, the penultimate partial printing may cause deformation in the main scanning direction. And, in the range where the distance H is greater than A, the smaller the distance H, the closer the upstream end of the paper M is to the print head 110, and as the distance H increases, the farther the upstream end of the paper M is from the print head 110. For this reason, in the range where the distance H is greater than A, the smaller the distance H, the higher the probability R3 of paper staining due to deformation in the main scanning direction, and as the distance H increases, the probability R3 decreases, becoming 0 (FIG. 8B).

For this reason, when paper M2 is used, the distance H is determined so that both the probability R1 of paper stains occurring due to deformation in the transport direction and the probabilities R2 and R3 of paper stains occurring due to deformation in the main scanning direction are small. In this embodiment, the distance H is determined to be (A + ΔS), as shown in FIG. 8(B). That is, when paper M2 is used, the pressing reference position RP2 is set to a position that is the distance (A + ΔS) away from the upstream edge of paper M2 (FIG. 5).

As can be seen from the above description, according to this embodiment, when the CPU 210 causes the printing mechanism 100 to print the print image PI, it causes the CPU 210 to perform the final opposing partial printing, which is the last partial printing performed in a state where the paper M faces the pressing member 146, and before performing the final opposing partial printing, it causes the paper M to be transported a specific transport amount (D-NS). The CPU 210 controls the specific transport amount so that the opposing length of the paper M changes depending on the positions of the ends Exr and Exl of the paper M in the main scanning direction and the position of the pressing member 146 in the main scanning direction (FIGS. 4 and 5). Specifically, the positional relationship between the positions of the ends Exr and Exl of the paper M in the main scanning direction and the position of the pressing member 146 in the main scanning direction differs depending on the length Lx of the paper M in the main scanning direction (FIGS. 4 and 5), so that a different pressing reference position RP is set depending on the length Lx of the paper M in the main scanning direction of the paper M (S105 in FIG. 6, FIGS. 4 and 5). As a result, the opposing length of the paper M changes depending on the positions of the ends Exr and Exl of the paper M in the main scanning direction and the position of the pressing member 146 in the main scanning direction (Figures 4 and 5).

As described above, the likelihood of paper stains due to deformation in the main scanning direction varies depending on the position of the end of the paper M in the main scanning direction and the position of the pressing member 146 in the main scanning direction. In addition, the longer the facing length of the paper M, the further the upstream corners Cl and Cr of the paper are from the print head 110, making it less likely that paper stains due to deformation in the main scanning direction will occur. According to this embodiment, the facing length of the print medium is changed depending on the positions of the ends Exr and Exl in the main scanning direction of the paper M and the position of the pressing member 146 in the main scanning direction. As a result, for example, if the positions of the ends Exr and Exl in the main scanning direction of the paper M and the position of the pressing member 146 in the main scanning direction are in a positional relationship that makes problems such as paper stains likely to occur, the facing length of the paper M can be increased to suppress the problems. Therefore, problems due to deformation of the paper M can be suppressed.

Furthermore, as shown in FIG. 4, the number of partial printing operations can be reduced by shortening the facing length of the paper M. For this reason, for example, if the positions of the ends Exr, Exl of the paper M in the main scanning direction and the position of the pressing member 146 in the main scanning direction are in a positional relationship that makes it difficult for problems such as paper stains to occur, a decrease in printing speed can be suppressed by shortening the facing length of the paper M.

Furthermore, according to the above embodiment, the CPU 210 further transports the paper M (sheet transport T3 in FIG. 5) after the final opposed partial printing (partial printing at head position P3 in FIG. 5), and then performs non-opposed partial printing (partial printing at head position P4 in FIG. 5) in a state where the paper M is not opposed to the pressing member 146 (one-sided holding state). The non-opposed partial printing is performed using the nozzle NZ at the downstream end in the transport direction, out of the multiple nozzles NZ that can be used, without using the nozzle NZ at the upstream end in the transport direction (FIG. 5). Specifically, by setting the sheet transport T3 in FIG. 5 to the nozzle length D, partial printing at head position P4 in FIG. 5 can be performed using only some of the nozzles NZ on the downstream side in the transport direction.

With the above configuration, the head separation length ΔLy (Figure 2 (A)) can be shortened when printing the non-opposing portion, which makes it possible to suppress paper stains caused by deformation in the transport direction when printing the non-opposing portion.

Furthermore, according to this embodiment, the specific transport amount (transport amount TL of sheet transport T3) differs depending on the distance in the main scanning direction (non-pressing length ΔLx in FIG. 4 and FIG. 5) between the ends Exr and Exl in the main scanning direction of the paper M and the opposing member (the member of the pressing member 146 that faces the paper M). That is, the specific transport amount is controlled so that the opposing length is d1 (FIG. 4) when the non-pressing length ΔLx is a first distance (for example, non-pressing length ΔLx=0 in FIG. 4). And, the specific transport amount is controlled so that the opposing length is d2 (FIG. 5) longer than d1 when the non-pressing length ΔLx is a second distance longer than the first distance (for example, non-pressing length ΔLx>0 in FIG. 5).

As described above, the longer the non-pressing length ΔLx, the more likely paper stains due to deformation in the main scanning direction are to occur. According to this embodiment, when the non-pressing length ΔLx is long and paper stains due to deformation in the main scanning direction are likely to occur, the facing length is increased so that the upstream angles Cl and Cr of the paper M are moved away from the print head 110, thereby suppressing paper stains due to deformation in the main scanning direction.

Furthermore, according to this embodiment, the specific transport amount (transport amount TL of sheet transport T3) is controlled so that the opposing length of paper M is d1 when the ends Exr, Exl of paper M in the main scanning direction face the pressing member 146 (Figure 4), and is controlled so that the opposing length of paper M is d2, which is longer than d1, when the ends Exr, Exl of paper M in the main scanning direction do not face the pressing member 146 (Figure 5).

As described above, when the ends Exr, Exl of the paper M in the main scanning direction do not face the pressing member 146, paper stains due to deformation in the main scanning direction are more likely to occur than when the ends Exr, Exl of the paper M in the main scanning direction face the pressing member 146. According to this embodiment, when the ends Exr, Exl do not face the pressing member 146 and paper stains due to deformation in the main scanning direction are more likely to occur, the facing length is increased so that the upstream corners Cl, Cr of the paper M are away from the print head 110, thereby suppressing paper stains due to deformation in the main scanning direction.

Furthermore, in the above embodiment, the opposing length is changed by changing the pressing reference position RP depending on the type of paper M (S106 in FIG. 6, FIGS. 4 and 5). That is, the specific transport amount (transport amount TL of sheet transport T3) is controlled so that the opposing length of paper M is d1 when paper M is a first type of paper (e.g., paper M1), and is controlled so that the opposing length of paper M is d2, which is different from d1, when paper M is a second type of printing medium (e.g., paper M2) different from the first type of printing medium, in this printing device.

The ease with which the paper M bends and its positional relationship with the pressing member 146 differs depending on the type of paper M (e.g., material, thickness, size), and therefore the ease with which paper stains due to deformation in the main scanning direction and deformation in the transport direction occur also differ. According to this embodiment, by changing the pressing reference position RP depending on the type of paper M, for example, when paper M that is more likely to cause paper stains due to deformation in the main scanning direction is used, the upstream corners Cl and Cr of the paper M can be made to be farther away from the print head 110, so that, for example, paper stains due to deformation in the main scanning direction can be suppressed.

In this embodiment, the first type of print medium (e.g., paper M1) and the second type of print medium (e.g., paper M2) differ in at least the length Lx in the main scanning direction (FIGS. 4 and 5). As described above, when the length Lx in the main scanning direction of paper M differs, the positional relationship between the positions of the ends Exr and Exl in the main scanning direction of paper M and the position of the pressing member 146 in the main scanning direction differs. According to the above configuration, by changing the opposing length of paper M according to the length Lx in the main scanning direction of paper M, the opposing length of paper M can be changed according to the positional relationship between the positions of the ends Exr and Exl in the main scanning direction of paper M and the position of the pressing member 146 in the main scanning direction. Therefore, paper stains caused by deformation in the main scanning direction can be appropriately suppressed according to the length Lx in the main scanning direction of paper M.

In this embodiment, the pressing member 146 is a member for holding the paper M in a wavy deformed state along the main scanning direction (Figure 3). In this configuration, the paper M can be deformed so that the ends Exr and Exl of the paper M in the main scanning direction face the print head 110, making it easy for paper stains to occur due to deformation in the main scanning direction. According to this embodiment, in cases where paper stains are likely to occur due to deformation in the main scanning direction, paper stains due to deformation in the main scanning direction can be appropriately suppressed.

Furthermore, in this embodiment, as described with reference to FIG. 8, the facing length of the paper M is determined based on a first probability (e.g., probability R1) of paper stains occurring due to deformation in the transport direction and a second probability (e.g., R2, R3) of paper stains occurring due to deformation in the main scanning direction, so as to suppress both the first probability and the second probability. As a result, paper stains can be appropriately suppressed. Note that since paper stains occur when the paper comes into contact with the print head 110, the probability of paper stains occurring can also be said to be the probability of the paper coming into contact with the print head 110.

B. Second embodiment FIG. 9 is an explanatory diagram of printing on paper M1 in the second embodiment. In the first embodiment, when the facing length is set to the lower limit d1, the upstream end of the print image PI can be printed in the final facing partial printing, so the final facing partial printing is the last partial printing (FIG. 4). In the second embodiment, the configuration of the printing mechanism is different, and the distance hsb (FIG. 9) in the transport direction between the print head 110 and the pressing member 146b is longer than the distance hs (FIG. 4) in the transport direction between the print head 110 and the pressing member 146 in the first embodiment. For this reason, in the second embodiment, even if the facing length is set to the lower limit db1, the upstream end of the print image PI cannot be printed in the final facing partial printing. For this reason, in the second embodiment, even if the facing length is set to the lower limit db1, partial printing in a one-side holding state (partial printing at head position P4 in FIG. 9) is executed as the last partial printing after the final facing partial printing.

Figure 10 is an explanatory diagram of printing on paper M2 in the second embodiment. In the second embodiment, the facing length db2 when paper M2 is used is longer than the facing length db1 when paper M1 is used, as in the first embodiment.

Figure 11 is an explanatory diagram of a method for setting the pressing reference position RP in the second embodiment. Figure 10 (A) is a graph showing the relationship between the pressing reference position RP and the probability of a malfunction when paper M1 is used. Figure 10 (B) is a graph showing the relationship between the pressing reference position RP and the probability of a malfunction when paper M2 is used.

In the second embodiment, as in the first embodiment, the pressing reference position RP is set taking into consideration the probability R1 that paper stains will occur due to deformation in the transport direction in the last partial print, the probability R2 that paper stains will occur due to deformation in the main scanning direction in the last partial print, and the probability R3 that paper stains will occur due to deformation in the main scanning direction in the penultimate partial print.

When a pressing reference position RP where the distance H is Ab (left end of the graph) is adopted, the end pressing head position is set so that the opposing length is at the lower limit db1. The lower limit db1 of the opposing length is, for example, the same as the lower limit d1 in the first embodiment. The number of partial printings performed after partial printing performed at a head position where at least some of the nozzles NZ are located upstream (-Y side) of the pressing reference position RP is two or less. For this reason, the pressing reference position RP is not set so that the distance H from the bottom edge of the paper to the pressing reference position RP is greater than 2D (D is the nozzle length D).

When the distance H is Ab (H=Ab), paper stains due to deformation in the transport direction may occur when the final partial printing is performed in the one-sided holding state, so the probability R1 of the paper stains is greater than 0. The farther the pressing reference position RP is from the bottom edge of the paper M, the more the end pressing head position shifts downstream, and the longer the head separation length ΔLy is during the final partial printing. Therefore, the greater the distance H, the higher the probability R1 of paper stains due to deformation in the transport direction (the range Ab<H<2D on the graph). The probability R1 of paper stains due to deformation in the transport direction is the same for paper M1 and paper M2 (Figures 11(A) and 11(B)).

When paper M1 is used, as shown in FIG. 9, in the double-sided holding state, the X-direction ends Exl and Exr of paper M1 are pressed by the pressing member 146. Also, in the single-sided holding state, as described above, paper staining caused by deformation in the main scanning direction is not an issue. For this reason, when paper M1 is used, deformation in the main scanning direction is unlikely to occur in either the double-sided holding state or the single-sided holding state. For this reason, when paper M1 is used, the probabilities R2 and R3 of paper staining caused by deformation in the main scanning direction occurring are 0 (FIG. 11 (A)).

For this reason, when paper M1 is used, the distance H is determined to be Ab so that the probability R1 of paper staining due to deformation in the transport direction is minimized, as shown in FIG. 11(A). In other words, when paper M1 is used, the pressing reference position RP1 is set to a position that is a distance Ab away from the upstream edge of paper M1 (FIG. 9).

When paper M2 is used, as shown in FIG. 10, in the both-side holding state, the X-direction ends Exl and Exr of paper M2 are not pressed by the pressing member 146. For this reason, when paper M2 is used, in the both-side holding state, paper stains due to deformation in the main scanning direction may occur. The closer the upstream corners Cl and Cr of paper M2 are to the print head 110, the higher the probability R3 that paper stains due to deformation in the main scanning direction will occur in the last but one partial printing performed in the both-side holding state. The shorter the distance H, the closer the upstream corners Cl and Cr of paper M2 are to the print head 110 in the last but one partial printing. For this reason, in the example of FIG. 11(B), when the distance H is Ab, the probability R3 is the highest, and as the distance H increases, the probability R3 decreases to 0.

Even when paper M2 is used, in the one-sided holding state, as described above, paper staining due to deformation in the main scanning direction is not a problem. For this reason, the probability R2 of paper staining due to deformation in the main scanning direction occurring in the final partial printing performed in the one-sided holding state is 0.

For this reason, when paper M2 is used, the distance H is determined so as to reduce both the probability R1 that paper stains due to conveyance direction deformation will occur in the final partial print, and the probability R3 that paper stains due to main scanning direction deformation will occur in the penultimate partial print. In this embodiment, the distance H is determined to be (Ab + ΔSb), as shown in FIG. 11(B). That is, when paper M2 is used, the pressing reference position RP2 is set to a position a distance (Ab + ΔSb) away from the upstream end of paper M2 (FIG. 10). As a result, the facing length of paper M2 in the final facing partial print is set to db2, which is larger than the lower limit db1.

As can be seen from the above explanation, in the second embodiment as well, the appropriate opposing length (db1 or db2) is set when paper M1 is used and when paper M2 is used. As a result, it is possible to appropriately suppress both paper stains caused by deformation in the main scanning direction and paper stains caused by deformation in the transport direction.

C. Modification (1) In each of the above embodiments, the length Lx of the paper M1 and the paper M2 in the main scanning direction is different, and the facing length of the paper M in the final facing portion printing is different depending on the length Lx in the main scanning direction. Instead of this, for example, even if the size of the paper M1 and the paper M2 is the same, if at least one of the material and the thickness is different, the facing length of the paper M in the final facing portion printing may be changed. For example, even if the size of the paper M1 and the paper M2 is the same, if at least one of the material and the thickness is different, the deformation characteristics of the paper (ease of bending, rigidity, etc.) are different, so that the above-mentioned probabilities R1, R2, R3 (FIGS. 8 and 11) are different between the paper M1 and the paper M2. This makes it possible to appropriately suppress paper staining by changing the facing length depending on at least one of the material and the thickness.

(2) In each of the above embodiments, the pressing member 146 is a member for holding the paper M in a wavy deformed state along the main scanning direction. Without being limited to this, the pressing member 146 may be a member that faces the paper M without deforming the paper M along the main scanning direction. Even in this case, for example, the paper M may be deformed along the main scanning direction due to deformation caused by ink seeping into the paper. In such a case, for example, by changing the facing length of the paper M depending on the type of paper M, paper stains can be appropriately suppressed as in the embodiments.

(3) In each of the above embodiments, cut paper is used as the paper M. Alternatively, for example, roll paper may be used, which is formed by rolling up a long piece of paper that is longer in the transport direction than the cut paper into a cylindrical shape. When such roll paper is used, there is a type of printer that completes printing after cutting the roll paper using a cutter provided upstream of the upstream roller pair 142 in the transport direction AR in the printing mechanism. In such printers, even when roll paper is used, paper stains due to deformation in the main scanning direction or transport direction at the upstream end of the paper after cutting can be a problem. In such cases, by changing the facing length of the paper M depending on the type of paper M, as in each of the above embodiments, paper stains can be appropriately suppressed as in the embodiments.

(4) The printing process in FIG. 6 and the print data output process in FIG. 7 are examples and are not limited to these. For example, in the processes in FIG. 6 and FIG. 7, the entire image data is converted into print data (S130 in FIG. 6), and then the print data output process in FIG. 7 is executed. Alternatively, for example, the print data conversion may be executed for each raster data acquired in S200 in FIG. 7. Also, in the print data output process, the raster data is sequentially assigned to the nozzles to be used, and each time the assignment for one partial print is completed, the assigned raster data group is output as partial print data for one partial print. Alternatively, the print data may be divided to generate all partial print data, and the transport amount for all sheet transports may be determined, and then the partial print data and the transport amount data may be output.

(5) As the print medium, other media such as OHP film, CD-ROM, and DVD-ROM may be used instead of paper M.

(6) In each of the above embodiments, the control device that executes the printing process in FIG. 6 is the CPU 210. Alternatively, the control device may be another type of device, for example, the user's terminal device 300. In this case, for example, the terminal device 300 operates as a printer driver by executing a driver program, and executes the printing process in FIG. 6 as part of its function as the printer driver. In this case, the terminal device causes the printer 200 to execute printing by supplying partial print data and carry amount data to the printer 200 as a print execution unit.

(7) The control device that executes the printing process in FIG. 6 may be, for example, a server that acquires image data from the printer 200 or the terminal device 300, generates the partial print data and transport amount data described above using the image data, and transmits these data to the printer 200. Such a server may be multiple computers that can communicate with each other via a network.

(8) In each of the above embodiments, a part of the configuration realized by hardware may be replaced by software, and conversely, a part or all of the configuration realized by software may be replaced by hardware. For example, a part of the printing process in FIG. 6 may be realized by a dedicated hardware circuit (e.g., an ASIC) that operates according to instructions from the CPU 210.

The present invention has been described above based on examples and modifications, but the above-mentioned embodiments of the invention are intended to facilitate understanding of the present invention and do not limit the present invention. The present invention may be modified or improved without departing from the spirit and scope of the claims, and the present invention includes equivalents thereof.

100...printing mechanism, 110...printing head, 111...nozzle formation surface, 120...head drive unit, 130...main scanning unit, 133...carriage, 134...sliding shaft, 140...conveying unit, 141...downstream roller pair, 142...upstream roller pair, 145...paper stand, 146, 146b...pressing member, 200...printer, 210...CPU, 220...non-volatile storage device, 230...volatile storage device, 231...buffer area, 26 0...operation unit, 270...display unit, 280...communication unit, 300...terminal device, HP...high support member, HP...each support member, LP...low support member M, M1, M2...paper, NC, NM, NK, NY...nozzle row, NZ...nozzle, P0-P4...head position, PG...computer program, PI, PI1, PI2...printed image, RL...raster line, RP, RP1, RP2...pressing reference position, T0-T3...sheet transport

Claims (12)

A printing device including a print execution unit and a control device,
The print execution unit is
a transport unit that transports the print medium in a transport direction;
a print head having a plurality of nozzles that eject ink of a specific color, the plurality of nozzles being positioned at different positions in the transport direction, and ejecting ink onto the printing medium to form dots on the printing medium;
an opposing member that is capable of opposing a printing surface of the printing medium on an upstream side of the plurality of nozzles of the print head in the transport direction;
Equipped with
the control device causes the print execution unit to print a print image by executing partial printing to form the dots by the print head and conveying the print medium by the conveying unit a plurality of times;
When causing the print execution unit to print the print image, the control device
performing a final opposed partial printing, which is the last partial printing performed in a state in which the printing medium is opposed to the opposed member;
before executing the final opposing portion printing, the print medium is conveyed by a specific conveyance amount;
the control device controls the specific transport amount so that an opposing length of the printing medium changes in accordance with a position of an end of the printing medium in a direction perpendicular to the transport direction and a position of the opposing member in the direction perpendicular to the transport direction;
A printing device, wherein the facing length is a length in the transport direction of a portion of the print medium that faces the facing member when printing the final facing portion. 2. The printing device according to claim 1,
The control device further comprises:
After the final opposing portion is printed, the print medium is transported.
After the print medium is conveyed, non-opposing portion printing is performed in a state where the print medium is not opposed to the opposing member;
The non-opposing partial printing is performed using, of a plurality of usable nozzles, a nozzle at a downstream end in the transport direction, without using a nozzle at an upstream end in the transport direction. 3. The printing device according to claim 1,
The specific conveyance amount is
When a distance in the perpendicular direction between the edge of the printing medium in the perpendicular direction and the opposing member is a first distance, the opposing length of the printing medium is controlled to be a first length;
When the distance is a second distance greater than the first distance, the facing length of the print medium is controlled to be a second length greater than the first length. 3. The printing device according to claim 1,
The specific conveyance amount is
When the edge of the printing medium in the orthogonal direction faces the facing member, the facing length of the printing medium is controlled to be a third length,
A printing device in which, when the orthogonal end of the printing medium does not face the opposing member, the opposing length of the printing medium is controlled to be a fourth length that is longer than the third length. The printing device according to any one of claims 1 to 4,
The specific conveyance amount is
When the print medium is a first type of print medium, the facing length of the print medium is controlled to be a fifth length;
A printing device, wherein when the print medium is a second type of print medium, the facing length of the print medium is controlled to be a sixth length different from the fifth length. 6. The printing device according to claim 5,
A printing device, wherein the first type of print medium and the second type of print medium differ in length at least in the orthogonal direction. 6. The printing device according to claim 5,
A printing device, wherein the first type of print medium and the second type of print medium are different in at least one of material and thickness. The printing device according to any one of claims 1 to 7,
A printing device, wherein the print medium is a cut sheet of paper that has been cut to have a specified length in the transport direction. A printing device according to any one of claims 1 to 8,
The printing device, wherein the opposing member is a member for holding the print medium in a state in which the print medium is deformed into a wave shape along the perpendicular direction. A printing device according to any one of claims 1 to 9,
A printing device in which the opposing length of the printing medium is determined based on a first probability that the printing medium will come into contact with the print head due to deformation in the perpendicular direction and a second probability that the printing medium will come into contact with the print head due to deformation in the transport direction, so as to suppress both the first probability and the second probability. A printing device according to any one of claims 1 to 10,
the print execution unit further includes a carriage that carries the print head and scans the print medium in the perpendicular direction;
The control device executes the partial printing by causing the print head to eject ink onto the print medium while scanning the carriage in the perpendicular direction. A computer program for a control device that controls a print execution unit,
The print execution unit is
a transport unit that transports the print medium in a transport direction;
a print head having a plurality of nozzles that eject ink of a specific color, the plurality of nozzles being positioned at different positions in the transport direction, and ejecting ink onto the printing medium to form dots on the printing medium;
an opposing member that is capable of opposing a printing surface of the printing medium on an upstream side of the plurality of nozzles of the print head in the transport direction;
Equipped with
the computer program causes a computer of the control device to execute partial printing to form the dots by the print head and conveying the print medium by the conveying unit a plurality of times, thereby causing the print execution unit to print a print image;
The computer program, when causing the print execution unit to print the print image,
performing a final opposed partial printing, which is the last partial printing performed in a state in which the printing medium is opposed to the opposed member;
before executing the final opposing portion printing, the print medium is conveyed by a specific conveyance amount;
the specific transport amount is controlled such that a facing length of the print medium changes in accordance with a position of an end of the print medium in a direction perpendicular to the transport direction and a position of the facing member in the direction perpendicular to the transport direction;
The opposing length is a length in the transport direction of a portion of the print medium that faces the opposing member when printing the final opposing portion.

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