JP2013212659A - Printing device and printing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printing device and a printing method for keeping image quality of printed matter at a high level.SOLUTION: A printing device includes color ink nozzle rows of a plurality of colors and black ink nozzle rows. The color ink nozzle rows and the black ink nozzle row are disposed side by side in a direction orthogonal to a conveyance direction of a medium. The color ink nozzle rows have printing heads arranged in the conveyance direction of the medium and assigned per color, and a head driving unit for scanning the printing head in a direction orthogonal to the conveyance direction of the medium. The printing head records dots discretely by the respective nozzles disposed parallel to respective color ink nozzles of each color in the black ink nozzle rows so that black dots are recorded to overlap.

Description

  The present invention relates to a printing apparatus that performs printing using color ink and black ink, and a printing method.

  Conventionally, in a printing apparatus, dots in a printed image are formed by ejecting ink from nozzles in accordance with the movement of the print head. There is also known a printing apparatus including a print head in which a color ink nozzle row for discharging color ink and a black ink nozzle row for discharging black ink are arranged in parallel in the paper transport direction. In such a printing apparatus, the number of color ink nozzles and the black ink nozzle row corresponding to the amount of medium fed can form a dot row of a predetermined width at one time (for example, Patent Document 1, 2).

JP 2004-322638 A JP 2001-146032 A

  Dot recording is performed by ink that has landed on the medium penetrating into the medium and fixing. Further, the time required for fixing the ink depends on the ink characteristics, the type of paper, and the amount of ink applied per unit. For this reason, in a printing apparatus in which the dot rows are arranged vertically, the amount of ink discharged per scan increases, so the dots are not formed correctly due to mixing with other ink before the ink is fixed. was there. In particular, when fixing high-density ink, if the dots are not fixed correctly, dot defects tend to be noticeable, and there has been a concern about the deterioration in the image quality of the printed image.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a printing apparatus and a printing method for maintaining the image quality of printed matter at a high level.

  In order to solve the above-described problem, the present invention includes a nozzle row of a plurality of color inks and a nozzle row of black ink, and the nozzle row of color ink and the nozzle row of black ink are provided on a medium. The color ink nozzle rows are arranged side by side in the direction orthogonal to the transport direction, the print heads are arranged in the medium transport direction for each color, and the head scans the print head in the direction orthogonal to the medium transport direction. A printing unit, and the print head records the dots by dividing the nozzles adjacent to the color ink nozzles of the color ink in the black ink nozzle row so that the black dots are overlaid. .

In the invention configured as described above, in the print head in which the nozzle rows are arranged vertically, the nozzles provided alongside the color ink nozzles of the respective colors in the black ink nozzle row are recorded so that the black dots are overlaid. Divide and record dots.
As a result, it is possible to hold the fixing time of each dot by dividing and recording the dots as compared to the case where all the dots are recorded at once. In addition, since the amount of ink landing at one time can be reduced, the fixing time can be shortened.

1 is a block diagram illustrating a printing apparatus according to the present invention. 1 is a block diagram illustrating a printing apparatus according to the present invention. FIG. 4 is an image diagram illustrating the arrangement of each nozzle row of the print head 8. FIG. 3 is a diagram illustrating a print image printed by the printer. It is a figure explaining the relationship between the scanning of the printing head 8, and the area | region where a dot is recorded. It is a figure explaining recording of Bk dot. It is a figure explaining the recording method of Bk dot of the present invention. 6 is a flowchart illustrating an example of a printing apparatus. It is a figure explaining the production | generation of the raster data of Bk.

1. First embodiment:
The printing apparatus according to the present invention will be described below.

FIG. 1 is a block diagram illustrating a printing apparatus according to the present invention. FIG. 2 is a block diagram illustrating a printing apparatus according to the present invention.
In FIG. 1, a printer 1 and a personal computer 10 are connected via a network or a cable, and function as a printing device in a broad sense as a whole.

  A personal computer (hereinafter also referred to as a PC) 10 includes a CPU (Central Processing Unit) 11, a HDD (Hard Disk Drive) 12, a RAM (Random Access Memory) 13, and an output I / F 14. . Each unit is connected via the bus 15 and is driven under the integrated control of the CPU 11. Further, the PC 10 is connected to the printer 1 via the output I / F 14, and can output various data to the printer 1 through the output I / F 14.

  The CPU 11 executes an application program 12a and a driver program 12b recorded in the HDD 12 under the operation of the operating system. The application program 12a causes the CPU 11 to realize various application functions. As an example, the application program 12a causes the CPU 11 to generate image data in response to a user operation input.

The driver program 12b causes the CPU 11 to generate printing data for controlling printing. The print data includes raster data (described later) created based on the image data and control commands for causing the printer 1 to execute print processing. Therefore, the CPU 11 functions as a color conversion module M1, a halftoning module M2, and an interlace module M3 for generating print data by the function of the driver program 12b.
Here, the color conversion module M1 converts the image data generated using the application into ink amount data indicating the amount of ink used.
The halftoning module M2 binarizes the ink amount data and converts it into dot data.
The interlace module M3 converts the array data constituting the dot data into raster data corresponding to the amount of ink output in one main scan of the printer 1. Raster data is data recorded by a single paper feed.

  As shown in FIG. 2, the printer 1 is connected to the PC 10 via an input interface (I / F) 2. The input I / F 2 is connected to a bus 3, and a main controller 4, a head controller 5, a carriage 6, a paper feed mechanism 7, and a print head 8 are further connected to the bus 3.

  The main controller 4 is composed of, for example, an ASIC (Application Specific Integrated Circuit), and includes a CPU as a calculation unit and a RAM as an internal memory. When the main controller 4 receives printing data from the PC 10 through the input I / F 2, the main controller 4 drives each unit based on the printing data to control the printing process.

  The head controller 5 includes a CMY controller unit 5a that is color ink and a Bk controller unit 5b that is black ink. A print head 8 having a color ink nozzle row and a black ink nozzle row is connected to the head controller 5, the color ink nozzle row is controlled by the CMY controller unit 5 a, and the black ink nozzle row is It is controlled by the controller unit 5b for Bk.

  FIG. 3 is an image diagram for explaining the arrangement of the nozzle rows of the print head 8. In FIG. 3, the left side is the color ink nozzle row, and the right side is the black ink nozzle row. Also, the arrangement direction of the numbered nozzles is the direction in which the paper is conveyed (hereinafter also referred to as the sub-scanning direction). The direction in which the color ink nozzle row and the black ink nozzle row are arranged side by side is a direction orthogonal to the sub-scanning direction (hereinafter also referred to as a main scanning direction).

  The color ink nozzle row is composed of a C row for discharging C (cyan) ink, an M row for discharging M (magenta) ink, and a Y row for discharging Y (yellow). Specifically, from the upper side in the figure, they are assigned in the order of YMC to the three regions of the tip, center, and tail. Each color nozzle row is composed of M nozzles, and each of the C row, M row, and Y row is constituted.

  The Bk ink nozzle row is arranged in parallel with the color ink nozzle row in the main scanning direction. In the present embodiment, the Bk ink nozzle row is configured by the same number of nozzles as the total number of color ink nozzles (ie, N × M = 3M). In the drawing, the Bk ink nozzle and the color ink nozzle are provided at the same position in the main scanning direction, but the present invention is not limited to this. For example, the Bk ink nozzle and the color ink nozzle may be arranged so as to be shifted by a predetermined distance in the sub-scanning direction (so-called staggered pattern).

Further, the Bk ink nozzles form a group according to the arrangement position. Originally, color inks of different colors are assigned to the color ink nozzle rows, so that they become Y rows, M rows, and C rows, and one row to which black ink is assigned becomes a simple Bk row. However, in order to facilitate printing control, the Bk columns are also grouped into Bk1, Bk2, and Bk3 columns corresponding to the respective color inks.
In this way, when the color ink has three colors, the nozzle row of the Bk ink is divided into three areas adjacent to the nozzle rows of the respective colors (C, M, Y) and grouped, which will be described later. In this way, printing is performed in each area.

  The carriage (head drive unit) 6 is a mechanism that reciprocates the print head 8 in the main scanning direction. The carriage 6 is fixed to the print head 8 and moves the print head 8 in the forward direction or the backward direction in accordance with driving of a carriage motor (not shown). Here, the printer 1 performs reciprocal path printing that ejects ink on the movement path (outward path and return path) of the print head 8. In the forward path and the return path, ink rows belonging to the above-described groups are used, and ink is recorded.

  The paper feeding mechanism 7 conveys the paper every predetermined distance. The paper feed mechanism 7 is a mechanism including a transport roller and a paper feed motor that drives the transport roller, and is installed in a transport path inside the printer 1. In this embodiment, the paper feed mechanism 7 transports the paper by the same distance as the color ink nozzle row in one paper feed. That is, when each of the C, M, and Y nozzle rows is configured with M nozzles, the paper feed mechanism 7 transports the paper every M dots.

  FIG. 4 is a diagram for explaining a print image printed by the printer 1. FIG. 5 is a diagram for explaining the relationship between the scanning of the print head 8 and the area where dots are recorded. FIG. 6 is a diagram illustrating a Bk dot recording method. FIG. 7 is a diagram for explaining the Bk dot recording method of the present invention. In FIG. 5, in order to simplify the description, the recording area on the sheet is divided into four for each color, and the data for each color recorded in each area is represented by DCi, DMi, DYi, DBki (i: 1 to 4). And

  In FIG. 4, since the paper is conveyed upward by the paper feeding mechanism 7 in the drawing, an image is shown in which the print head 8 is gradually lowered. The print head 8 is reciprocated along the main scanning direction by the carriage 6, and each one scan becomes the forward path or the backward path. Further, as shown in the figure, the sheet is conveyed by an amount corresponding to the length of the nozzle row of each color. That is, paper feeding corresponding to the length of the nozzle row for each color in the color ink nozzle row is performed for one forward or backward scan. On the drawing, from left to right, forward path, return path, forward path, return path, forward path, and return path are for convenience, such as 1 pass, 2 pass, 3 pass, 4 pass, 5 pass, 6 pass, and K pass. Call.

  As described above, when ink is recorded by reciprocating the print head 8, the printing order of the color dots (C, M, Y) and Bk dots formed in the forward path and the backward path is different. It becomes. That is, since the color nozzle row and the Bk nozzle row are provided side by side in the main scanning direction, the recording order of Bk dots and color dots is in the forward path, and the recording order of color dots and Bk dots is in the backward path.

  Further, in FIG. 6, when Bk dots are recorded only in the Bk3 column, dots having an M dot width are fixed to the medium by one scan. In such a case, the Bk ink may not be correctly fixed on the paper, and the dot shape may be deteriorated. Here, since the density of ink is proportional to the number of dots that are shot per unit area, when the density of Bk ink is increased, the number of dots recorded on the paper also increases. As a result, the fixing time of each dot cannot be secured, and the dot shape may be significantly degraded.

  Therefore, in the present invention, as shown in FIG. 7, when Bk dots are recorded on a sheet, the dots are divided and recorded in the Bk3, Bk2, and Bk1 columns that constitute the Bk ink nozzle array. In addition, by recording each dot in an overlapping manner, the amount of ink landing per scan is reduced, and the dot fixing time is secured.

  Specifically, referring to FIG. 4, in the first pass, only the C column and the Bk3 column are included in the print area. FIG. 5 shows that dots are recorded based on DC1 and DBk1. Although it is natural that the C column prints DC1 for recording color dots, it indicates which one of the Bk1, Bk2, and Bk3 columns is used for the DBk1 recording. Here, the Bk3 row is used for the first pass Bk1, but not all the dots are recorded in the Bk3 row, but only predetermined dots are recorded in the Bk3 row.

The second pass is a return pass, but in this second pass, the C, M, Bk2, and Bk3 columns are in the print area. Since DC1 has already been printed for the color ink, DC2 is printed in the C column and DM1 is printed in the M column.
For one black ink, the Bk3 column records DBk2. Also at this time, not all dots are recorded by the Bk3 row. On the other hand, in the Bk2 row, a predetermined nozzle is used, and dots are recorded so as to overlap with the dot recording positions recorded in the Bk3 row in DBk1.

The third pass is the forward path, but in this third pass, the C, M, Y, Bk2, Bk3, and Bk1 columns are in the print area. For color ink, DC3 is recorded in the C column, DM2 is recorded in the M column, and DY1 is recorded in the Y column.
For one black ink, DBk3 is recorded in the Bk3 column. In the Bk2 column, DBk2 is recorded. Then, in the Bk1 row, a predetermined nozzle is used to record dots by superimposing at positions where dots are recorded in either the Bk3 row or the Bk2 row in DBk1.

  That is, in DBk1, the target dots are recorded by being overlapped by the scanning of the print head 8 three times (outward, backward, and forward). With such a configuration, when a dot having a certain density is recorded, the dot shape can be maintained by overlapping the dots with the nozzles of the Bk3 row, the Bk2 row, and the BK1 row. That is, as compared with the case where a large number of dots are recorded at a time, the time required for fixing each dot can be ensured by dividing and recording the dots.

  Further, since the dot density per unit area can be changed by changing the number of times of overlapping dots, the density of the printed image can be controlled as a result. For example, the dot density changes when the dot is shot at the same position in any of the three scans and when the dot is shot at the same position in any two of the three scans. Will be controlled.

Next, an embodiment in such a printing apparatus will be described.
FIG. 8 is a flowchart for explaining an embodiment of the printing apparatus. FIG. 9 is a diagram for explaining generation of Bk raster data.

  In this embodiment, a case where a Bk solid image is recorded as print data in addition to a color image will be described as an example. Also, the printing process shown in FIG. 8 is started by issuing a print command on an application executed on the PC 10.

  In step S1, the color conversion module M1 of the PC 10 converts the R, G, B color component values of the image data included in the print data into ink amount data composed of C, M, Y, K color component values. . The color conversion module M1 performs color conversion processing using a color conversion LUT that records the correspondence between R, G, and B color component values and C, M, Y, and K color component values.

  In step S2, the halftoning module M2 of the PC 10 binarizes the ink amount data and converts the ink amount data into dot data corresponding to ON / OFF of the droplet discharge at each nozzle. The dot data is data configured by vertically and horizontally arranging data indicating dot on / off according to the resolution of the image data (for example, “1”, “0”). After the halftoning process, dot data of four planes of CMYK matching the nozzle density is generated.

  In step S3, the interlace module M3 generates raster data necessary for driving the color ink nozzles of the print head 8. In this embodiment, for ease of explanation, it is assumed that the print head 8 records ink using eight nozzles constituting each color nozzle row. Therefore, the interlace module M3 acquires raster data for eight arrays from the dot data. Color dot raster data is generated for each of C, M, and Y colors.

  In step S4, the interlace module M3 detects the density of the Bk ink. If the ink density is equal to or higher than the threshold value, the process proceeds to step S5. Here, the ink density means the amount of ink used for reproducing the gradation value designated by the image data. On the other hand, if the ink density is equal to or lower than the threshold value, the interlace module M3 proceeds to step S6. As an example of the method by which the interlace module M3 determines the ink density, it may be determined from the K (black) color component value (tone value) of the ink amount data acquired in step S1, or after the halftoning process. You may judge from the dispersion | distribution degree of a dot.

  When the ink density is equal to or lower than the threshold value (step S4: NO), the interlace module M3 records a predetermined number of dots in one scan using any of the Bk3 column, the Bk2 column, and the BK1 column. That is, when the ink density is low, the dot density is low and there is no need to record the dots in a dispersed manner. Therefore, in step S6, raster data necessary for driving the nozzles of the predetermined Bk row of the print head 8 is generated. In this step, since Bk ink is not overprinted, for example, Bk dots are recorded only in the Bk3 row. Therefore, the interlace module M3 generates raster data for the Bk3 column. The number of dots defined by the raster data is specified by the dot data.

  On the other hand, when the ink density is equal to or higher than the threshold value (step S4: YES), the interlace module M3 records the dots by dividing them into the Bk3 column, the Bk2 column, and the BK1 column. Therefore, in step S5, the interlace module M3 generates raster data according to the arrangement of dots recorded by the Bk3 column, the Bk2 column, and the Bk1 column.

  In FIG. 9, a case where dots are overlapped and recorded by raster data divided into three will be described as an example. For example, in FIG. 9A, description will be given by taking, as an example, data in which j is arranged in the main scanning direction and k is arranged in the sub scanning direction (k = 8 in the figure). The Bk ink nozzle row, Bk3 row, Bk2 row, and Bk1 row that record dots using each data are shown as “3”, “2”, and “1”, respectively. The case where dots are recorded at the same position in the Bk3 column, Bk2 column, and Bk1 column is also referred to as “3.2”, “3.1”, and “2.1”.

  When the dots are overlapped and recorded twice while being divided into three in each column, it is necessary to perform recording twice with at least the nozzles in the Bk3 column, Bk2, and Bk1 column that have the same arrangement order within the group. Further, since the number of dots corresponding to a certain ink density is divided and recorded, the raster data for each column has a designated dot number of ½. In FIG. 9A, among the data, 8 columns, 5 columns, and 2 columns are data recorded by being overlapped by the Bk3 column and the BK2 column. In addition, the 5th and 3rd columns are data recorded by overlapping the Bk3 column and the BK1 column. Further, the 7th, 4th, and 1st columns are data recorded by being overlapped with the Bk2 and Bk1 columns.

  As an example in which the interlace module M3 generates raster data, raster data for the Bk3 column, Bk2 column, and Bk1 column is generated by mask processing. That is, as shown in FIG. 8B, the interlace module M3 extracts raster data recorded in the Bk3 column from the j × k data cut out from the dot data using the mask for the Bk3 column. . Similarly, as shown in FIGS. 8C and 8D, the interlace module M3 extracts raster data recorded by the respective nozzles in the Bk2 row and Bk1 using the corresponding mask. The extracted raster data for the Bk3 column, the B2 column, and the Bk1 column are rearranged according to the timing of the used nozzles of the print head 8.

  In step S <b> 7, the CPU 11 compresses the raster data and supplies it to the printer 1 as print data through the output I / F 14 of the PC 10.

  In step S8, the main controller 4 of the printer 1 receives the compressed printing data from the PC 10, and releases the compression of the printing data.

In step S9, the main controller 4 outputs the C, M, and Y raster data to the CMY controller unit 5a, and outputs the Bk raster data to the Bk controller unit 5b.
Therefore, the CMY controller unit 5a generates a CMY drive signal for driving the nozzles based on the raster data of each color, and drives the nozzle row of each color. Since the raster data for color nozzles is supplied for eight arrays of the same color at a time, the CMY controller unit 5a once drives the color nozzle corresponding to the corresponding color specified by the raster data. In this scan, an 8-dot row is recorded.

  On the other hand, when the ink density is equal to or higher than the threshold, the Bk controller unit 5b generates a Bk drive signal for driving the nozzle row based on the raster data for each row shown in FIG. Drive.

Hereinafter, how dots are formed in each scan will be described with reference to FIG.
First, in the first pass, in accordance with the movement of the print head 8 in the forward direction, recording of the 8-1 dot row of C ink and Bk 8 rows, 6 rows, 5 rows, using Bk 3 rows, Three rows and two rows of dots are recorded. Next, in the second pass, in accordance with the movement of the print head 8 in the backward direction, recording of the 8-1 dot row of M ink and data 8 rows, 7 rows, 5 rows, using Bk2 rows, Each row of 4 rows, 2 rows and 1 row is recorded. Then, in the third pass, in accordance with the movement of the print head 8 in the forward direction, recording of the 8-1 dot row of Y ink and data 2 rows, 3 rows, 5 rows, 6 using the Bk1 row Rows and 8 rows of dots are recorded.

  Therefore, the color ink is recorded with a width of 8 dots by one scanning. On the other hand, the Bk ink has an 8-dot width recorded by three scans. At this time, an area in which dots are overlapped in a certain area is generated. Therefore, even when the density of Bk dots is increased, the dots can be dispersed and recorded, and the time for fixing each dot on the medium can be secured. As a result, the image quality can be maintained at a high level.

  Furthermore, if the Bk dots are overlapped by reciprocating scanning, the recording order of the color dots and Bk dots changes for each predetermined dot, so that it is possible to make the dot printing unevenness difficult to see. That is, since recording with a predetermined dot width is performed in the forward path and the backward path of the print head 8, the recording order of color dots and Bk dots changes for each predetermined dot. As a result, it is possible to make the printing unevenness difficult to see.

2. Other Embodiments The timing for generating the raster data of the Bk3 column, the Bk2 column, and the Bk1 column may be performed by the printer 1. In this case, first, the PC 10 transmits data of a predetermined number of dots from the dot data to the printer 1. Then, the main controller 4 of the printer 1 generates raster data by the same method as the interlace module M3. With the above configuration, the printer 1 can apply the present invention to any print data supplied from the PC 10.

  Further, the configuration of the printing apparatus by the printer 1 and the PC 10 is an example, and the printing apparatus may be realized by the printer 1 alone.

  The use of the Bk ink nozzle row divided into N according to the number N of color inks is an example, and the used nozzles can be appropriately changed within a range in which print unevenness in the printed image is not noticeable.

  Needless to say, the present invention is not limited to the above embodiments. That is, the mutually replaceable members and configurations disclosed in the above embodiments are applied by appropriately changing the combination thereof, and the known technologies and the members and configurations disclosed in the above embodiments are mutually compatible. It is assumed that the members and configurations that can be replaced with the above are appropriately replaced, and that combinations thereof are changed and applied, and that those skilled in the art will substitute for the members and configurations disclosed in the above-described embodiments based on known techniques. It is disclosed as an embodiment of the present invention to appropriately replace the obtained member, configuration, and the like, and to change and apply the combination.

  DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Input I / F, 3 ... Bus, 4 ... Main controller, 5 ... Head controller, 5a ... CMY controller part, 5b ... Bk controller part, 6 ... Carriage, 7 ... Paper feed mechanism, 8 ... print head, 10 ... personal computer, 11 ... CPU, 12 ... HDD, 12a ... application program, 12b ... driver program, 13 ... RAM, 14 ... output I / F, M1 ... color conversion module, M2 ... halftoning module, M3 ... Interlace module

Claims (6)

A plurality of color ink nozzle rows and a black ink nozzle row, wherein the color ink nozzle row and the black ink nozzle row are juxtaposed in a direction perpendicular to a medium transport direction; The ink nozzle rows are arranged in the medium transport direction for each color and assigned to the print head,
A head drive unit that scans the print head in a direction orthogonal to the conveyance direction of the medium,
The printing apparatus, wherein the print head divides and records dots at each nozzle provided adjacent to the color ink nozzles of each color in the black ink nozzle row so that black dots are recorded in an overlapping manner.   The printing apparatus according to claim 1, wherein the print head changes the number of times the dots are overlapped according to the density of the black ink. The head drive unit reciprocates the print head,
The printing apparatus according to claim 1, wherein the print head records dots on an outward path and a return path. When the number of colors of the color ink is N,
The nozzle row of each color ink is composed of M nozzles,
4. The printing apparatus according to claim 1, wherein the black ink nozzle row is configured by N × M nozzles. 5.   The printing apparatus according to claim 1, wherein the transport distance of the medium is every number of nozzles in the nozzle row of each color ink. A plurality of color ink nozzle rows and a black ink nozzle row, wherein the color ink nozzle row and the black ink nozzle row are arranged side by side in a direction perpendicular to a medium transport direction; The nozzle row is a printing method using a printing apparatus provided with a print head allocated in line in the medium conveyance direction for each color,
Scanning the print head in a direction orthogonal to the transport direction of the medium, and
A printing method in which dots are recorded by being divided by each nozzle provided adjacent to the color ink nozzle of each color in the black ink nozzle row so that black dots are recorded in an overlapping manner.

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