JP7492195B2 - Control device, computer program - Google Patents

Description

This specification relates to technology for controlling a print execution unit.

In inkjet serial printers that print by performing multiple main scans of the print head, there is a known technique for printing using paper (also called long paper) that is longer in the transport direction during printing than standard paper sizes such as A4, B5, and L size. For example, Patent Document 1 discloses an inkjet printer that prints on roll paper without leaving any margins (so-called long borderless printing).

JP 2005-115528 A

Here, due to manufacturing errors, etc., the print head may be positioned at an angle to the paper transport direction during printing. This tilt of the print head may cause a problem in which the lines extending in the transport direction in the printed image are misaligned (hereinafter, also referred to as line misalignment).

This specification discloses a technology that can prevent noticeable line misalignment caused by print head tilt when a relatively long print medium is used.

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

[Application Example 1] A control device for a print execution unit including a print head having multiple nozzles whose positions in the sub-scanning direction are different from each other, a main scanning unit that performs a main scan to move the print head along a main scanning direction that intersects with the sub-scanning direction relative to a print medium, and a sub-scanning unit that performs a sub-scan to move the print medium along the sub-scanning direction relative to the print head, the control device including an information acquisition unit that acquires medium information regarding a medium length, which is the length of the print medium in the sub-scanning direction, and a print control unit that causes the print execution unit to print a print image by causing the print execution unit to perform partial printing to form dots by the print head while performing the main scan and the sub-scanning multiple times, and the print control unit determines whether or not the print image is printed based on the medium information before the print image is printed. A control device that executes a first printing control when the medium length is a first length, and executes a second printing control when the medium length determined based on the medium information is a second length longer than the first length, the first printing control being a control that executes N times (N is an integer equal to or greater than 1) of front partial printing when printing an image for a unit length in the sub-scanning direction, the second printing control being a control that executes M times (M is an integer satisfying N<M) of partial printing when printing an image for the unit length, and the maximum length of the sub-scan executed between the first partial printing and the Mth partial printing in the second printing control is shorter than the maximum length of the sub-scan executed between the first partial printing and the Nth partial printing in the first printing control.

The more the number of partial printings is increased and the shorter the maximum length of the sub-scanning is, the more the line misalignment described above can be suppressed. According to the above configuration, when a print medium with a relatively long second length is used, line misalignment can be suppressed by increasing the number of partial printings and shortening the maximum length of the sub-scanning. As a result, when a print medium with a relatively long second length is used, it is possible to suppress noticeable line misalignment caused by the tilt of the print head.

The technology disclosed in this specification can be realized in various forms, such as a control device for a print execution unit, a printing method, a printing device, a computer program for realizing the functions of the method or device, a recording medium on which the computer program is recorded (e.g., a non-transitory recording medium), 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. FIG. 4 is a diagram showing an example of a UI screen for inputting a print instruction. 4 is a flowchart of a printing process. FIG. FIG. FIG. FIG.

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 for the print mechanism 100, a non-volatile storage device 220 such as a hard disk drive, a volatile storage device 230 such as a hard disk or flash memory, 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 printer 200 is connected to an external device, for example, a user's terminal device (not shown) 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 CP. In this embodiment, the computer program CP is a control program for controlling the printer 200. The computer program CP may be provided by being stored in the non-volatile storage device 220 when the printer 200 is shipped. Alternatively, the computer program CP 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. By executing the computer program CP, the CPU 210 controls, for example, the print mechanism 100 to perform the printing process described below.

The printing mechanism 100 prints by ejecting ink (droplets) of each of the following colors: cyan (C), magenta (M), yellow (Y), and black (K). 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 (A), the main scanning unit 130 includes a carriage 133 that carries the print head 110, and a sliding shaft 134 that 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 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 unit 140 holds the paper M and transports the paper M in a transport direction AR (the +Y direction in FIG. 2) that intersects with the main scanning direction. As shown in FIG. 2A, the transport unit 140 includes a paper tray 145, an upstream roller pair 142, and a downstream roller pair 141. 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 formation surface 111 of the print head 110. The paper M is transported by driving the downstream roller pair 141 and the upstream roller pair 142 by a transport motor (not shown).

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 the nozzles NZ are 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. In this embodiment, the nozzle interval NT of each nozzle row is an interval equivalent to 300 dpi, that is, (1/300) inch.

Of the nozzles that make up these nozzle rows, the nozzle NZ located most upstream (-Y side) is also called the most upstream nozzle NZu. Furthermore, of these nozzles, the nozzle NZ located most downstream (+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 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.

A-2. Printing Overview The CPU 210 prints an image on the paper M by alternately executing partial printing, in which the print head 110 ejects ink to form dots on the paper M, and sub-scanning (transporting the paper M) by the transport unit 140 multiple times while causing the main scanning unit 130 to perform main scanning.

Figure 3 is an explanatory diagram of the printing overview. Figure 3 (B) shows a print image OIa to be printed on paper M. The print image OIa includes multiple partial images PI1 to PI5. Each partial image is printed by one partial printing. The printing direction of partial printing is either the forward pass direction or the return pass direction. In other words, partial printing is either forward pass printing, in which dots are formed while performing a main scan in the forward pass direction (+X direction in Figure 3), or return pass printing, in which dots are formed while performing a main scan in the return pass direction (-X direction in Figure 3). In Figure 3, solid arrows in the +X direction or -X direction are attached within the partial images. Partial images PI1, PI3, and PI5 with solid arrows in the +X direction are printed by forward pass printing. Partial images PI2 and PI4 with solid arrows in the -X direction are printed by return pass printing.

As shown in FIG. 3B, the printing in this embodiment is bidirectional printing in which forward and return printing are performed alternately. In FIG. 3B, the arrow in the -Y direction from one partial image (e.g., partial image PI1) to another partial image (e.g., partial image PI2) adjacent in the -Y direction corresponds to the transport (sub-scan) of the paper M. That is, the arrow in the -Y direction in FIG. 3B indicates that the print head 110 moves in the -Y direction relative to the paper M shown in FIG. 3B as the paper M is transported. The printing shown in FIG. 3B is so-called one-pass printing, and the length of each partial image in the transport direction and the transport amount of the paper M in one pass are the nozzle length D.

3A is a diagram explaining the misalignment of the nozzle NZ in the main scanning direction. In order to avoid cluttering the figure, FIG. 3A illustrates a simplified print head 110 having only one nozzle row for ink of one color. The misalignment of the nozzle NZ in the main scanning direction is when the position of the most upstream nozzle NZu is shifted in the main scanning direction from the designed position relative to the position of the most downstream nozzle NZd. Such misalignment occurs, for example, when the print head 110 is tilted relative to the designed position, as shown in FIG. 3A. In the example of FIG. 3A, due to the tilt of the print head 110, the direction in which the nozzle row extends is tilted by an angle θ with respect to the transport direction AR (Y direction). As a result, the position of the most upstream nozzle NZu is shifted in the main scanning direction by Δx relative to the position of the most downstream nozzle NZd from the designed position.

Due to this positional misalignment, an image misalignment in the main scanning direction occurs where a specific partial image meets the downstream end (end in the +Y direction) of the partial image printed next to the specific partial image. In the example shown in FIG. 3B, there is a misalignment of Δx between the upstream end (end in the -Y direction) of partial image PI1 and the downstream end (end in the +Y direction) of partial image PI2 to be printed next. Because of this, a misalignment occurs in the straight line LN extending in the Y direction on the print image OIa, for example, in the portion indicated by the dashed circle Ca. A similar phenomenon occurs with other partial images, for example, between partial image PI2 and partial image PI3. This phenomenon is also referred to below as "line misalignment."

In order to prevent line misalignment, it is known to control the print position of a partial image (e.g., PI2) to be printed next to a specific partial image (e.g., PI1) without misalignment in the main scanning direction (called position correction control). The print mechanism 100 of this embodiment is capable of executing position correction control. FIG. 3B illustrates a print image OIa when position correction control is not performed, and FIG. 3C illustrates a print image OIb when line misalignment correction control is performed. In the example of FIG. 3C, the print position of a partial image (e.g., PI2) to be printed next to a specific partial image (e.g., PI1) is shifted by Δx in the -X direction by position correction control. By position correction control, no line misalignment occurs on the straight line LN extending in the Y direction on the print image OIb, for example, in the part indicated by the dashed circle Cb.

When position correction control is performed, the positions of the partial images PI1 to PI5 in the main scanning direction shift little by little, causing the width of the margin along the edge of the print paper in the main scanning direction on the paper M to vary. For example, in the example of FIG. 3C, the margin width Wub on the upstream side in the transport direction is narrower than the margin width Wdb on the downstream side in the transport direction. The difference between the upstream margin width Wub and the downstream margin width Wdb becomes larger as the length of the paper M in the transport direction AR becomes longer, which becomes a problem.

This phenomenon does not occur if position correction control is not performed. For example, in the example of FIG. 3B, the margin width Wua on the upstream side in the conveying direction and the margin width Wda on the downstream side in the conveying direction are approximately the same.

In this embodiment, taking into consideration the line misalignment and margin width fluctuations described above, print control is changed between the case where short paper, which is relatively short in the transport direction, is used and the case where long paper, which is relatively long in the transport direction, is used. Short paper is, for example, standard paper such as A4, A3, B5, and postcards. Long paper is, for example, roll paper or paper that is longer in the transport direction than the standard paper prepared by the user.

A-3. Printing Process The printing process is executed, for example, when a print instruction is input from the user to the printer 200. The print instruction is input via a user interface screen (UI screen) displayed on the display unit 270. The print instruction includes printing condition information (described later) indicating various printing-related conditions, and information specifying target image data indicating the target image to be printed.

Figure 4 shows an example of a UI screen for inputting print instructions. The UI screen WI1 in Figure 4 (A) includes input elements for specifying one valid option from among a number of options corresponding to each of a number of setting items related to printing. Specifically, the UI screen WI1 includes a pull-down menu PM1 for inputting setting information from a number of options, a number of radio buttons RB1 to RB6, and a number of buttons BT1 to BT3.

The pull-down menu PM1 is an input element for inputting the size of the paper M as the printing medium. In this embodiment, the options available are standard short paper such as A4 or A3, long paper (e.g., 297 mm x 1200 mm paper), and user-defined size paper. User-defined size paper is a size that has been registered by the user in advance. The user can register any size of paper via another UI screen WI2 (described later in FIG. 4B) that is displayed when button BT1 is pressed.

Radio buttons RB1 and RB2 are input elements for inputting an instruction to print on the paper in portrait or landscape orientation. Radio buttons RB3 and RB4 are input elements for inputting a designation of the color mode of printing. In this embodiment, there are two color mode options: monochrome mode and color mode.

Radio buttons RB5 and RB6 are input elements for inputting the print mode designation. In this embodiment, there are two image quality mode options: high quality mode and normal mode. Images printed in high quality mode have higher image quality than images printed in normal mode. However, the time required for printing in high quality mode is longer than the time required for printing in normal mode. The difference in print control between high quality mode and normal mode will be described later.

When the print button BT2 is pressed on the UI screen WI1, the setting information indicating the option currently specified on the UI screen WI1 is stored as the valid setting information for the corresponding setting item. The valid setting information can be said to be a type of condition information included in the print instruction.

The UI screen WI2 in FIG. 4(B) is a screen for the user to register the size of the paper M. The UI screen WI2 includes two radio buttons RB7 and RB8, two input fields IS1 and IS2, and two buttons BT4 and BT5.

Radio buttons RB7 and RB8 are input elements for inputting the units used when inputting the size of paper M. In this embodiment, there are two unit options: millimeters and inches. Input field IS1 is an input element for inputting the paper width as a numerical value. Input field IS2 is an input element for inputting the paper height as a numerical value.

When the OK button BT4 is pressed on the UI screen WI2, the size indicated by the units currently selected via the radio buttons RB7 and RB8 and the numerical values entered in the two input fields IS1 and IS2 is registered.

Figure 5 is a flowchart of the printing process. In S10, the CPU 210 acquires target image data specified by information included in the print command. The target image data in this embodiment is acquired, for example, from the non-volatile storage device 220. Alternatively, the target image data may be acquired from an external device (not shown) connected to the printer 200 (for example, a terminal device such as a smartphone, or a storage device such as a USB memory). The target image data is RGB image data that includes RGB values for each pixel. The RGB values are, for example, color values in the RGB color system that include three component values of red (R), green (G), and blue (B).

In S15, the CPU 210 acquires printing condition information. The acquired printing condition information is information input by the user via the UI screens WI1 and WI2 described above. As described above, the printing condition information includes information indicating the size of the paper M, information indicating the paper orientation, and information indicating the printing mode.

In S20, the CPU 210 determines whether the paper M is long or short based on information indicating the size of the paper M to be used for printing and information indicating the paper orientation (vertical or horizontal). Specifically, when A3 or A4 paper M is specified, the paper M is determined to be short. When long paper is specified, the paper M is determined to be long. When a user-defined size is specified and the length of the transport direction AR of the paper M registered by the user is less than a predetermined threshold (e.g., 1000 mm), the paper M is determined to be short. When a user-defined size is specified and the length of the transport direction AR of the paper M registered by the user is equal to or greater than a predetermined threshold, the paper M is determined to be long. When the vertical direction is specified as the paper orientation, the height of the paper is the length of the paper transport direction AR, and when the horizontal direction is specified as the paper orientation, the width of the paper is the length of the paper transport direction AR. As can be seen from the above explanation, the information indicating the size of the paper M and the information indicating the paper orientation can be said to be paper information regarding the length of the paper M in the transport direction AR.

If the paper M is a short sheet of paper (S20: NO), in S25 the CPU 210 determines whether the print mode is high quality mode or normal mode based on the information indicating the print mode. If the print mode is normal mode (S25: NO), in S30 the CPU 210 determines the print control to be executed as short-length normal control. If the print mode is high quality mode (S25: YES), in S35 the CPU 210 determines the print control to be executed as short-length high quality control.

If the paper M is long paper (S20: YES), in S40, the CPU 210 determines whether the print mode is high-quality mode or normal mode based on the information indicating the print mode. If the print mode is normal mode (S40: NO), in S45, the CPU 210 determines the print control to be executed as long-size normal control. If the print mode is high-quality mode (S40: YES), in S50, the CPU 210 determines the print control to be executed as long-size high-quality control.

In S55, the CPU 210 generates print data showing a print image using the target image data (RGB image data). Specifically, the CPU 210 performs a resolution conversion process on the RGB image data. The resolution conversion process is a process of adjusting the number of pixels in the vertical and horizontal directions of the image shown by the RGB image data according to the print resolution in the conveying direction AR and the main scanning direction of the print to be performed. The resolution conversion process is an enlargement process when the number of pixels is increased, and a reduction process when the number of pixels is decreased. The CPU 210 performs a color conversion process on the RGB image data that has been subjected to the resolution conversion process. The color conversion process is a process of converting the RGB values of a plurality of pixels contained in the RGB image data into CMYK values. The CMYK values are color values of the CMYK color system that include component values (in this embodiment, the component values of C, M, Y, and K) corresponding to the ink used for printing. The color conversion process is performed, for example, by referring to a known lookup table that specifies the correspondence between RGB values and CMYK values. The CPU 210 performs halftone processing on the target image data that has already been color converted to generate print data (also called dot data). The print data is data that represents the dot formation state for each pixel for each of the CMYK color components. The value of each pixel in the print data indicates the dot formation state in two gradations, for example "no dot" and "dot", or in four gradations, "no dot", "small", "medium", and "large". The halftone processing is performed using known techniques such as dithering and error diffusion.

In S60, the CPU 210 causes the printing mechanism 100 to execute printing using the print data. At that time, the CPU 210 causes the printing mechanism 100 to execute printing according to the determined print control. For example, the CPU 210 divides the print data to generate partial print data for the printing mechanism 100 to execute multiple partial prints. The CPU 210 adds control data indicating the transport amount of the paper M, etc. to the partial print data, and outputs the data to the printing mechanism 100, thereby causing the printing mechanism 100 to execute printing. As a result, the print image is printed on the paper M.

A-4. Description of Print Control Next, the four types of print control mentioned above, that is, short size normal control, long size normal control, short size high quality control, and long size high quality control, will be described.

A-4-1. Short-length normal control Fig. 6 is an explanatory diagram of short-length normal control. The print image OI printed on the paper M includes multiple raster lines RL that extend in the X direction (the main scanning direction during printing) in Fig. 6 and differ from one another in positions in the Y direction. Only two of the multiple raster lines RL are shown hatched in Fig. 6. Each raster line RL is a line on which multiple dots aligned along the main scanning direction can be formed.

In FIG. 6, the head position, i.e., the relative position of the print head 110 in the transport direction with respect to the paper M, is illustrated for each partial print (i.e., for each main scan). The head position when performing the kth partial print is called head position Pk. The transport of the paper M performed between the kth partial print and the (k+1)th partial print is also called the kth paper transport Tk. In FIG. 6, head positions P1 to P3 corresponding to the 1st to 3rd partial prints and the 1st to 3rd paper transports T1 to T3 are illustrated. Note that in FIG. 6 to FIG. 9, the hatched rectangular area indicating the head position indicates the area where the nozzle NZ to be used is located. In FIG. 6, the entire head positions P1 to P3 are hatched, which means that all the nozzles NZ can be used for printing at each head position.

In short normal control, the print resolution in the main scanning direction is 600 dpi, and the print resolution in the transport direction AR is 300 dpi. In short normal control, the transport amount of each paper transport Tk is the nozzle length D. In short normal control, each raster line RL is printed by only one partial printing. That is, all dots formed on each raster line are formed by one partial printing. Therefore, dots of a specific color on each raster line RL, for example, C dots, are formed using one nozzle NZ of the nozzle row NC that corresponds to that raster line RL. In short normal control, the position correction control described above is executed.

As can be seen from the above explanation, short-length normal control is what is known as one-pass printing, and the number of partial prints required to print an image of the nozzle length D is one.

A-4-2. Long normal control Fig. 7 is an explanatory diagram of long normal control. Fig. 7 shows a print image OI printed on paper M, similar to Fig. 6. Fig. 7 shows head positions P1 to P9 corresponding to the first to ninth partial printings, and first to eighth paper transports T1 to T8.

In long normal control, as in short normal control, the print resolution in the main scanning direction is 600 dpi, and the print resolution in the transport direction AR is 300 dpi. In long normal control, the transport amount of each paper transport Tk is (1/3) of the nozzle length D {(1/3) x D}.

In the long normal control, each raster line RL is printed by three partial printings. That is, the dots formed on each raster line are formed by one of the three partial printings. For example, the multiple dots to be formed on the raster line RL1 in FIG. 7 include dots formed by partial printing performed at head position P1, dots formed by partial printing performed at head position P2, and dots formed by partial printing performed at head position P3. The multiple dots to be formed on the raster line RL2 in FIG. 7 include dots formed by partial printing performed at head position P4, dots formed by partial printing performed at head position P5, and dots formed by partial printing performed at head position P6. Therefore, dots of a specific color on each raster line RL, for example, dots of C, are formed using the three nozzles NZ of the nozzle row NC that correspond to the raster line RL. In the short normal control, the position correction control described above is executed.

As can be seen from the above explanation, short-length normal control is what is known as three-pass printing, and the number of partial prints required to print an image of the nozzle length D is three.

A-4-3. Short length high image quality control Fig. 8 is an explanatory diagram of short length high image quality control. Fig. 8 shows a print image OI printed on a sheet of paper M, similar to Fig. 6. Fig. 8 shows head positions P1 to P6 corresponding to the first to sixth partial printings, and the first to fifth sheet transports T1 to T5.

In the short-length high-image-quality control, the print resolution in the main scanning direction is 600 dpi, and the print resolution in the transport direction AR is 600 dpi. As described above, the nozzle spacing NT of the print head 110 in this embodiment is equivalent to 300 dpi. Therefore, the print mechanism 100 cannot print an image with a print resolution of 600 dpi in the transport direction AR in one partial print. For this reason, in the short-length high-image-quality control in this embodiment, the print mechanism 100 prints odd-numbered raster lines RL counting from the downstream side of the transport direction AR in odd-numbered partial prints (for example, partial prints at head positions P1, P3, and P5 in FIG. 8). Then, the print mechanism 100 prints even-numbered raster lines RL counting from the downstream side of the transport direction AR in even-numbered partial prints (for example, partial prints at head positions P2, P4, and P6 in FIG. 8). This allows the printing mechanism 100 to print images with a print resolution of 600 dpi in the transport direction AR.

In short-length high-image-quality control, the transport amount for odd-numbered paper transports Tk (e.g., T1, T3, and T5 in FIG. 8) is half the nozzle spacing NT {(1/2) x NT}. The transport amount for even-numbered paper transports Tk (e.g., T2 and T4 in FIG. 8) is the nozzle length D minus half the nozzle spacing NT {D-(1/2) x NT}.

In short length high image quality control, each raster line RL is printed by only one partial printing. That is, all dots formed on each raster line are formed by one partial printing. Therefore, dots of a specific color on each raster line RL, for example, C dots, are formed using one nozzle NZ of the nozzle row NC that corresponds to that raster line RL. In short length normal control, the position correction control described above is executed.

As can be seen from the above explanation, short-length normal control is what is known as two-pass printing, and the number of partial prints required to print an image of the nozzle length D is two.

A-4-4. Long length high image quality control Fig. 9 is an explanatory diagram of long length high image quality control. Fig. 9 shows a print image OI printed on paper M, similar to Fig. 6. Fig. 9 shows head positions P1 to P11 corresponding to the 1st to 11th partial printings, and the 1st to 10th paper transports T1 to T10.

In long length high image quality control, the print resolution in the main scanning direction is 600 dpi, and the print resolution in the transport direction AR is 600 dpi. Therefore, similar to short length high image quality control, in long length high image quality control of this embodiment, the printing mechanism 100 prints odd-numbered raster lines RL in odd-numbered partial printing (e.g., partial printing at head positions P1, P3, P5 in FIG. 9). Then, the printing mechanism 100 prints even-numbered raster lines RL in even-numbered partial printing (e.g., partial printing at head positions P2, P4, P6 in FIG. 9). This allows the printing mechanism 100 to print an image with a print resolution of 600 dpi in the transport direction AR.

In long-length high-image-quality control, the transport amount of the paper transport Tk (for example, T1 to T10 in FIG. 8) is 1/4 of the nozzle length D {(1/4) x D}.

In long-length high-quality printing, each raster line RL is printed by two partial printings. That is, the dots formed on each raster line are formed by one of the two partial printings. For example, the dots to be formed on the odd-numbered raster line RL3 in FIG. 9 include dots formed by partial printing performed at head position P1 and dots formed by partial printing performed at head position P3. The dots to be formed on the even-numbered raster line RL4 in FIG. 9 include dots formed by partial printing performed at head position P7 and dots formed by partial printing performed at head position P9. Therefore, dots of a specific color on each raster line RL, for example, dots of C, are formed using two nozzles NZ of the nozzle row NC that correspond to the raster line RL. In long-length high-quality control, the position correction control described above is not performed.

As can be seen from the above explanation, long-length high-quality control is what is known as four-pass printing, and the number of partial prints required to print an image of the nozzle length D is four.

According to the embodiment described above, the CPU 210 acquires paper information (specifically, information indicating the size and direction of the paper M) regarding the length of the paper M in the transport direction AR (S15 in FIG. 5). When the length of the paper M determined based on the paper information is a first length (a length determined to be a short paper in this embodiment) (NO in S20 in FIG. 5), the CPU 210 executes a first print control (short normal control or short high-quality control in this embodiment) (S30 or S35 in FIG. 5). When the length of the paper M determined based on the paper information is a second length (a length determined to be a long paper in this embodiment) that is longer than the first length (YES in S20 in FIG. 5), the CPU 210 executes a second print control (long normal control or long high-quality control in this embodiment) (S45 or S50 in FIG. 5).

In this embodiment, the first printing control is a control that executes partial printing N times (N is an integer equal to or greater than 1) when printing an image of a unit length in the transport direction AR (for example, an image of the nozzle length D), and the second printing control is a control that executes partial printing M times (M is an integer that satisfies N<M) when printing an image of the unit length. For example, in the short-length normal control, which is the first printing control in the normal mode, one partial printing is executed when printing an image of the nozzle length D, as shown in FIG. 6 (N=1). In contrast, in the long-length normal control, which is the second printing control in the normal mode, three partial printings are executed when printing an image of the nozzle length D, as shown in FIG. 7 (M=3). For example, in the short-length high-quality control, which is the first printing control in the high-quality mode, two partial printings are executed when printing an image of the nozzle length D, as shown in FIG. 8 (N=2). In contrast, in the long-length high-quality control, which is the second printing control in the high-quality mode, four partial printings are executed when printing an image of the nozzle length D, as shown in FIG. 9 (M=4). Thus, in both normal and high-quality modes, when long paper is used, the number of partial prints performed when printing an image the length of the nozzle D is greater than when short paper is used (N<M).

Furthermore, in this embodiment, the maximum length of the paper transport (sub-scan) performed between the first partial print and the Mth partial print in the second print control is shorter than the maximum length of the paper transport performed between the first partial print and the Nth partial print in the first print control. For example, in the short normal control (FIG. 6), which is the first print control in the normal mode, the maximum length of the paper transport is the nozzle length D, as described above. In the long normal control (FIG. 7), which is the second print control in the normal mode, the maximum length of the paper transport is the nozzle length D (1/3) value {(1/3) x D}, as described above. For example, in the short high-quality control (FIG. 8), which is the first print control in the high-quality mode, the maximum length of the paper transport is the nozzle length D minus half the nozzle spacing NT {D-(1/2) x NT}. In the long high-quality control (FIG. 9), which is the second print control in the high-quality mode, the maximum length of the paper transport is the nozzle length D (1/4) value {(1/4) x D}. Thus, in both normal and high-quality modes, when long paper is used, the maximum length of paper transport is shorter than when short paper is used.

As a result, when long paper is used, the number of partial prints is increased and the maximum length of the sub-scan is shortened, thereby suppressing line misalignment when long paper is used. Therefore, when long paper is used, it is possible to suppress noticeable line misalignment caused by the tilt of the print head 110.

A more detailed explanation will be given. The line misalignment described in FIG. 3 occurs at the portion where the specific partial image and the downstream end (end in the +Y direction) of the partial image printed next to the specific partial image contact each other. The amount of line misalignment increases as the length of the paper transport executed between the specific partial image and the partial image printed next to the specific partial image becomes longer. For example, in the short normal control of FIG. 6, the length of the paper transports T1 to T3 is the nozzle length D, so the amount of line misalignment is Δx (FIG. 3(A)). In contrast, in the long normal control of FIG. 7, the length of the paper transports T1 to T8 is {(1/3)×D}, so the amount of line misalignment is {(1/3)×Δx}. If the length of the paper transports T1 to T3 is shortened, the number of partial prints required to print an image of the nozzle length D will inevitably increase. As can be seen from the above explanation, in this embodiment, when long paper is used, the number of partial prints is increased and the maximum length of the sub-scan is shortened, thereby suppressing line misalignment when long paper is used.

Furthermore, in this embodiment, when short paper is used, the number of partial prints is less than when long paper is used, so the decrease in printing speed when short paper is used can be suppressed. Long paper is expected to be used for printing large posters and the like. For this reason, when long paper is used, users expect a certain amount of printing time to be required, so they are unlikely to be dissatisfied even if the printing time is long. Short paper is expected to be used for printing everyday documents. For this reason, short paper is expected to be used more frequently than long paper, and a larger number of sheets are expected to be printed. For this reason, users have higher printing speed requirements for short paper than for long paper. In this embodiment, the decrease in printing speed when short paper is used can be suppressed, so user satisfaction can be increased.

Furthermore, according to this embodiment, as described above, in the first print control (FIGS. 6 and 8) executed when short paper is used, the CPU 210 executes position correction control to suppress line misalignment. As a result, it is possible to suppress noticeable line misalignment even when short paper is used. When position correction control is executed, as described with reference to FIG. 3(C), a difference occurs between the upstream margin width Wub and the downstream margin width Wdb, but with short paper in which the length of the paper M in the transport direction AR is relatively short, the difference in margin width is relatively small, so this is unlikely to be a problem.

Furthermore, according to this embodiment, as described above, in the second print control (FIGS. 7 and 9) in which long paper is used, the CPU 210 does not execute position correction control to suppress line misalignment. As a result, it is possible to suppress the occurrence of a difference between the upstream margin width Wub and the downstream margin width Wdb. With long paper in which the length of the paper M in the transport direction AR is relatively long, the difference in margin width caused by position correction control tends to be large, which can be problematic. According to this embodiment, such a problem does not occur.

As can be seen from the above explanation, according to this embodiment, by using different print controls depending on the length of the paper M in the transport direction AR, whether long or short paper is used, it is possible to prevent noticeable line misalignment caused by the tilt of the print head 110 and to prevent the difference between the upstream margin width Wub and the downstream margin width Wdb from becoming noticeable.

Furthermore, according to this embodiment, the print resolution in the transport direction AR (sub-scanning direction) of the print image OI printed by the second print control when long paper is used is equal to the print resolution in the transport direction AR of the print image OI printed by the first print control when short paper is used. For example, in normal mode, the print resolution in the transport direction AR is 300 dpi whether long paper or short paper is used (Figures 6 and 7). In high-quality mode, the print resolution in the transport direction AR is 600 dpi whether long paper or short paper is used (Figures 8 and 9). As a result, regardless of the length of the transport direction AR of the paper M, printing can be achieved at the same print resolution to provide the same appearance, while preventing line misalignment and differences in margin width from becoming noticeable as described above.

Furthermore, according to this embodiment, the first printing control is a control in which a plurality of dots constituting each of a plurality of raster lines are formed by partial printing P times (P is an integer equal to or greater than 1), and the second printing control is a control in which a plurality of dots constituting each of a plurality of raster lines are formed by partial printing Q times (Q is an integer satisfying P<Q). For example, in the short-length normal control, which is the first printing control, as shown in FIG. 6, a plurality of dots of each raster line are formed by one partial printing (P=1). In contrast, in the long-length normal control, which is the second printing control in normal mode, as shown in FIG. 7, a plurality of dots of each raster line are formed by three partial printings (Q=3). For example, in the short-length high-quality control, which is the first printing control in high-quality mode, as shown in FIG. 8, a plurality of dots of each raster line are formed by one partial printing (P=1). In contrast, in the long high quality control, which is the second print control in high quality mode, the multiple dots of each raster line are formed by two partial printings (Q=2), as shown in Figure 9. In this way, in both normal mode and high quality mode, when long paper is used, the number of partial printings required to form the multiple dots of each raster line is large (P<Q).

By forming the multiple dots of each raster line by multiple partial printings, it is possible to prevent all dots on one raster line RL from being misaligned in the same way relative to all dots on other raster lines. This makes it possible to prevent streaks known as banding from appearing in the printed image OI. When long paper is used, it is expected that a printed image OI such as a poster with many solid areas will be printed. Banding is likely to be noticeable in such printed images OI. In this embodiment, when long paper is used, banding can be suppressed by increasing the number of partial printings to form the multiple dots of each raster line.

Furthermore, by forming multiple dots for each raster line through multiple partial printings, it is possible to suppress line misalignment (Figure 3) that occurs between images printed through different partial printings. As a result, when long paper is used, it is possible to suppress noticeable line misalignment even without performing position correction control.

Furthermore, according to the above embodiment, the CPU 210 acquires paper information based on input from the user (S15 in Figs. 4 and 5). As a result, it is possible to appropriately switch between the first print control and the second print control based on the input from the user.

More specifically, the input from the user includes an input via the pull-down menu PM1 on the UI screen WI1 in FIG. 4(A). That is, the input from the user is an input to select an option corresponding to the size of the paper M to be used for printing from multiple options corresponding to multiple sizes of paper M. Then, based on the option selected by the user, the CPU 210 determines whether the length of the paper M is a first length (e.g., a length determined to be a short paper) or a second length (e.g., a length determined to be a long paper) (S20 in FIG. 5). As a result, it is possible to appropriately switch between the first print control and the second print control based on the option selected by the user.

Furthermore, the input from the user includes numerical values input into input fields IS1 and IS2 of UI screen WI2 in FIG. 4(B), i.e., input of a numerical value indicating the length of paper M. If the numerical value input by the user is less than a threshold value, CPU 210 determines that the length of paper M is a first length (e.g., a length determined to be a short sheet of paper), and if the numerical value is equal to or greater than the threshold value, CPU 210 determines that the length of paper M is a second length (e.g., a length determined to be a long sheet of paper). As a result, it is possible to appropriately switch between the first print control and the second print control based on the numerical value input by the user.

B. Modification (1) The print control of the above embodiment is an example, and is not limited to this. For example, the long normal control may be a control in which the length of paper transport is half the nozzle length D, and a partial image half the length of the nozzle length D is printed in one partial print. Even in this case, the maximum length of paper transport in the long normal control is shorter than the maximum length of paper transport in the short normal control, so that when long paper is used, it is possible to suppress noticeable line misalignment caused by the inclination of the print head 110.

For example, in the long length high image quality control, the length of paper transport may be half the nozzle length D. Then, odd-numbered raster lines RL may be printed in odd-numbered partial printing, and even-numbered raster lines RL may be printed in even-numbered partial printing. Then, each raster line RL may be printed in one partial printing, as in the short length high image quality control. Even in this case, printing with a print resolution of 600 dpi in the main scanning direction can be achieved. Even in this case, the maximum length of paper transport in the long length high image quality control is shorter than the maximum length of paper transport in the short length high image quality control, so that when long paper is used, noticeable line misalignment caused by the tilt of the print head 110 can be suppressed.

(2) In the above embodiment, if the print mode is the same, the print resolution in the transport direction AR is the same whether short paper or long paper is used. Alternatively, for example, if the print mode is the same, the print resolution in the transport direction AR may be 600 dpi when long paper is used, and the print resolution in the transport direction AR may be 300 dpi when short paper is used.

(3) In the above embodiment, the CPU 210 determines whether the paper M is short or long paper based on input from the user. Alternatively, for example, the CPU 210 may detect the length of the paper M in the transport direction AR using a sensor provided in the printer 200, and determine whether the paper M is short or long paper based on the detection result.

(4) In the above embodiment, the CPU 210 executes position correction control when short paper is used, and does not execute position correction control when long paper is used. Alternatively, for example, the CPU 210 may execute position correction control with a first correction amount (e.g., Δx) when short paper is used, and execute position correction control with a second correction amount smaller than the first correction amount when long paper is used so that the difference in margin width is not noticeable.

(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 the printing mechanism 100 of the above embodiment, the transport unit 140 transports the paper M, thereby moving the paper M relative to the print head 110 in the transport direction. Alternatively, the paper M may be moved relative to the print head 110 in the transport direction AR by moving the print head 110 in the opposite direction to the transport direction AR relative to the fixed paper M.

(7) In each of the above embodiments, the device that executes the printing process in FIG. 5 is the CPU 210 of the printer 200. Alternatively, a terminal device, such as a personal computer, connected to the printer 200 may execute the printing process in FIG. 5. In this case, the CPU of the terminal device executes the printing process in FIG. 5, for example, by executing a printer driver program. In this case, in S60 of FIG. 6, the CPU of the terminal device causes the printer 200, as a print execution unit, to execute printing by sending partial print data and control data to the printer 200.

Furthermore, the device that executes the printing process in FIG. 5 may be, for example, a server that acquires image data from a printer or a terminal device and generates a print job using the image data. Such a server may be multiple computers that can communicate with each other via a network.

(8) In each of the above embodiments, some of the configurations realized by hardware may be replaced by software, and conversely, some or all of the configurations realized by software may be replaced by hardware. For example, when the printing process of FIG. 5 is executed in printer 200, halftone processing and color conversion processing may be realized by a dedicated hardware circuit (e.g., ASIC) that operates according to instructions from CPU 210 of printer 200.

The present invention has been described above based on examples and modified examples, 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...print head, 111...nozzle formation surface, 120...head drive unit, 130...main scanning unit, 133...carriage, 134...sliding shaft, 140...transport unit, 141...downstream roller pair, 142...upstream roller pair, 145...paper tray, 200...printer, 210...CPU, 220...non-volatile storage device, 230...volatile storage device, 231...buffer area, 260...operation unit, 270...display unit, 280...communication unit, AR...transport direction, BT1 to BT4...buttons, CP...computer program, M...paper, NC, NK, NY, NM...nozzle row, NZ...nozzle, OI, OIa, OIb...printed image, WI1, WI2...UI screen

Claims (8)

A control device for a print execution unit, comprising: a print head having a plurality of nozzles at different positions in a sub-scanning direction; a main scanning unit that executes a main scan to move the print head along a main scanning direction that intersects with the sub-scanning direction relative to a print medium; and a sub-scanning unit that executes a sub-scan to move the print medium along the sub-scanning direction relative to the print head,
an information acquisition unit that acquires medium information related to a medium length, which is a length of the print medium in the sub-scanning direction;
a print control unit that causes the print execution unit to print a print image by causing the print execution unit to execute partial printing, which forms dots by the print head while performing the main scan, and the sub-scanning, multiple times;
Equipped with
the print control unit executes a first print control when the medium length determined based on the medium information is a first length, and executes a second print control when the medium length determined based on the medium information is a second length longer than the first length;
the first print control is a control for executing the partial printing N times (N is an integer equal to or greater than 1) when printing an image for a unit length in the sub-scanning direction,
the second print control is a control for executing the partial printing M times (M is an integer satisfying N<M) when printing the image of the unit length,
A control device, wherein the maximum length of the sub-scan executed between the first partial printing and the Mth partial printing in the second printing control is shorter than the maximum length of the sub-scan executed between the first partial printing and the Nth partial printing in the first printing control. The control device according to claim 1 ,
A control device, wherein a print resolution in the sub-scanning direction of a print image printed by the second print control is equal to a print resolution in the sub-scanning direction of a print image printed by the first print control. The control device according to claim 2,
the print image includes a plurality of raster lines, each of which includes a plurality of the dots aligned along the main scanning direction,
the first printing control is control for forming the plurality of dots constituting each of the plurality of raster lines by the partial printing P times (P is an integer equal to or greater than 1),
The control device, wherein the second printing control is control for forming the plurality of dots constituting each of the plurality of raster lines by the partial printing Q times (Q is an integer satisfying P<Q). The control device according to any one of claims 1 to 3,
The information acquisition unit acquires the medium information based on an input from a user. The control device according to claim 4,
the input from the user is an input for selecting an option corresponding to a size of the printing medium to be used for printing from a plurality of options corresponding to a plurality of sizes of the printing medium;
The print control unit determines whether the medium length is the first length or the second length based on an option selected by a user. The control device according to claim 4,
the input from the user is an input of a numerical value indicating the length of the medium;
The printing control unit determines that the medium length is the first length when the numerical value input by the user is less than a threshold value, and determines that the medium length is the second length when the numerical value input by the user is greater than or equal to the threshold value. The control device according to any one of claims 1 to 6,
the print control unit is capable of causing the print control unit to execute position correction control so as not to shift the printing position of the second partial image relative to the first partial image in the main scanning direction in order to suppress image misalignment in the main scanning direction at a portion where a first partial image printed in a first partial printing and a downstream end in the sub-scanning direction of a second partial image printed in a second partial printing performed following the first partial printing meet,
the first print control is a control for executing the position correction control,
The second print control is a control that does not execute the position correction control. A computer program for controlling a print execution unit including a print head having a plurality of nozzles at different positions in a sub-scanning direction, a main scanning unit that executes a main scan to move the print head along a main scanning direction that intersects with the sub-scanning direction relative to a print medium, and a sub-scanning unit that executes a sub-scan to move the print medium along the sub-scanning direction relative to the print head,
an information acquisition function for acquiring medium information relating to a medium length, which is the length of the printing medium in the sub-scanning direction;
a print control function that causes the print execution unit to print a print image by causing the print execution unit to execute partial printing, which forms dots by the print head while performing the main scan, and the sub-scanning, multiple times;
This is realized on a computer.
The print control function executes a first print control when the medium length determined based on the medium information is a first length, and executes a second print control when the medium length determined based on the medium information is a second length longer than the first length;
the first print control is a control for executing the partial printing N times (N is an integer equal to or greater than 1) when printing an image for a unit length in the sub-scanning direction,
the second print control is a control for executing the partial printing M times (M is an integer satisfying N<M) when printing the image of the unit length,
A computer program, wherein the maximum length of the sub-scan executed between the first partial printing and the Mth partial printing in the second printing control is shorter than the maximum length of the sub-scan executed between the first partial printing and the Nth partial printing in the first printing control.

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