Patent Grant
9022506
1. Technical Field
The present invention relates to a print control device, a print control method, and a print control program.
2. Related Art
A printer which discharges an ink from a nozzle for discharging an ink and performs a printing has been known. Such a printer discharges each ink such as black, cyan, magenta, yellow, and the like from each nozzle corresponding to respective inks. However, not every ink is always used in a printing, and monochrome printing is also performed where black ink only is used. In such a case, nozzles corresponding to inks other than a black ink are plugged by ink around the nozzles, which is dried and has increased viscosity since the frequency of use of the nozzle is low.
As a solution to the plugged nozzles, an image processing method that forms the image using a black ink and forms dots of the black ink and each color ink at the same position when an input image is in black has been known (refer to JP-A-2009-269321 and JP-A-2008-162258). In addition, an image forming apparatus has been known which has an ink usage adjustment unit adjusting the amount of use of the black ink and color inks and an image drawing unit drawing a monochrome image on a recording medium using the adjusted ink, and in which the ink usage adjustment unit adjusts the amount of use of each ink based on property of each ink to be used (drying characteristic of an ink) and a use environment (temperature, humidity, area, type of recording medium) so as not to get the nozzles plugged by drying of each ink (refer to JP-A-2010-184415).
As in each document described above, when a black ink and a color ink are used in printing a monochrome image, the influence of the color ink may cause an adverse effect that a density of black color of a printed result (referred to as an optical density (OD) value) is lower than a value originally expected and the printed result is in a gray color. In addition, as in JP-A-2009-269321 and JP-A-2008-162258 described above, a method of forming dots of color inks of different colors at the same position, when a positional deviation occurs between the dots to be formed at the same position due to transport accuracy of a print medium, positional accuracy of a print head and a nozzle, and the like, has blurring of an outline of the image and a hue deviation, thereby causing an image quality to be decreased.
An advantage of some aspects of the invention is to provide a technology which can reduce plugging of a nozzle and prevent a decrease in an image quality.
According to an aspect of the invention, there is provided a print control device which causes a monochrome image to be printed by discharge of a black ink from a nozzle for discharging an ink, and which discharges a chromatic color ink in addition to the black ink in a region where the amount of use of the black ink is indicated by the monochrome image data representing the monochrome image is equal to or higher than a threshold value.
In this configuration, the print control device can discharge the chromatic color ink in addition to the black ink only in a region where the amount of use of the black ink indicated by the monochrome image data is equal to or higher than the threshold value. Therefore, it is possible to substantially eliminate the effect of the chromatic color ink on the image quality of a print result of the monochrome image, and to reduce the plugging of a nozzle corresponding to the chromatic color ink.
In the print control device according to the aspect, the print control device may discharge chromatic color inks of different colors to positions which are not overlapped each other.
In this configuration, with respect to the above-describe region, dots of black ink do not overlap with a plurality of dots of the chromatic color inks of different colors in the print result. Therefore, the decrease in OD value, blurring of outlines, and a deviation of the hue in the print result are suppressed, so that the image quality may be prevented from being lowered.
In the print control device according to the aspect, the print control device may have the threshold value varying with respect to at least some colors among the chromatic color inks of different colors.
In this configuration, when using a plurality of types of chromatic color inks, the amount of use of the black ink which may allow discharge of the black ink and the chromatic color ink varies according to a color of the chromatic color ink. Therefore, it is possible to set the threshold value according to the intensity of an effect of each chromatic color ink on an appearance of the print result, and to accurately suppress a decrease in the image quality.
The intensity of the effect of each chromatic color ink on the appearance of the print result correlates with level of brightness of each chromatic color ink. In the print control device according to the aspect, the higher a brightness value of the chromatic color ink is, the lower the threshold value is.
In this configuration, the chromatic color ink where brightness is relatively high is discharged with the black ink in a region where the amount of use of the black ink is relatively low, and on the other hand, a chromatic color ink where brightness is low is discharged with the black ink in a region where the amount of use of the black ink is relatively high. Therefore, it is possible to ensure the image quality and to suppress the plugging of a nozzle in a good balance.
In the print control device according to the aspect, the chromatic color ink may be discharged prior to the black ink in the region.
In this configuration, when the chromatic color ink and the black ink are discharged to a certain region, the chromatic color ink is discharged first, and the black ink is discharged thereon. Therefore, it is possible to reduce more the effect of the chromatic color ink on the image quality of the print result of the monochrome image.
In the print control device according to the aspect, after discharging the black ink in a region where the amount of use of the black ink indicated by the monochrome image data does not reach the threshold value, cleaning processing may be performed which discharges a chromatic color ink to a position deviated from the print medium.
In this configuration, with respect to a region where the amount of use of the black ink is lower than the threshold value, the chromatic color ink is not discharged, but the cleaning processing is performed outside the print medium. Therefore, it is possible to avoid both a decrease in the image quality of the printed monochrome image and the plugging of a nozzle.
The technical concepts of the invention may be not only realized in a form of a print control device, but also embodied in other objects (devices). In addition, it is possible to understand the invention of a method (print control method) which includes a processing step corresponding to the features of the print control device according to any of the aspects described above, the invention of a print control program which causes a predetermined hardware (computer) to perform the method, and an invention of a computer-readable recording medium which records the program. In addition, the print control device may be realized by a single device, and may be realized by a combination of a plurality of devices. Additionally, a print control device may be realized by a single printing apparatus (printer) having a nozzle and a print head.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
The following describes an embodiment of the invention with reference to drawings.
A display 30 as a display unit is connected to the computer 10, and a user interface (UI) screen which is necessary for each processing is displayed on the display 30. In addition, the computer 10 appropriately includes an operation unit 40 which is realized by, for example, a keyboard, a mouse, a touch pad, a touch panel, or the like, and an instruction necessary for each processing is input through the operation unit 40 by a user. In addition, the printer 50 is connected to the computer 10. As described below, in the computer 10, a print command is generated by a function of the printer driver 13 based on image data where an image to be printed is represented, and a print command is sent to the printer 50.
In the printer 50, a CPU 51 expands program data 54 stored in a memory such as a ROM 53 and the like to a RAM 52 and performs a calculation according to the program data 54 under the OS, and thereby performs firmware FW for controlling the device itself. The firmware FW interprets the print command sent from the computer 10 to extract print data and send the print data to ASIC56, and thereby it is possible to perform printing based on the print data. In addition, the firmware FW can acquire image data where an image to be printed is represented from a memory card mounted on the connector for external connection which is not shown and an external device (for example, the computer 10), and the like, and generate print data based on the acquired image data. Even when the print data are generated by the function of the firmware FW, the print data are sent to the ASIC56.
The ASIC56 acquires the print data and generates a driving signal for driving a transport mechanism 57, a carriage motor 58, and a print head 62 based on the print data. The printer 50 includes a carriage 60, and the carriage 60 is equipped with an ink cartridge 61 for each of a plurality of ink types. In an example of
A specific type and a number of inks which are used by the printer 50 are not limited to those described above, and various inks may be used such as, for example, light cyan, light magenta, orange, green, gray, light gray, white, metallic ink, and the like. In addition, the ink cartridge 61 may be installed at a predetermined position in the printer 50 not equipped in the carriage 60. The carriage 60 includes the print head 62 ejecting (discharging) an ink supplied from each ink cartridge 61 from a plurality of nozzles for discharging an ink.
A density (the number of nozzles/inch) of nozzles Nz in each of the K nozzle row 62a and the chromatic nozzle row 62b, for example, is equal to print resolution (dpi) in the sub-scanning direction by the printer 50. The K nozzle row 62a and the chromatic nozzle row 62b may be not only configured to only have one row of nozzles aligned along the sub-scanning direction, but also configured to have a plurality of rows of nozzles which are parallel to each other and deviated at a predetermined pitch in the sub-scanning direction. Furthermore, the chromatic nozzle row 62b includes a nozzle row (C nozzle row) formed of a plurality of nozzles Nz (C nozzles) for discharging the C ink, a nozzle row (M nozzle row) formed of a plurality of nozzles Nz (M nozzles) for discharging the M ink, and a nozzle row (Y nozzle row) formed of a plurality of nozzles Nz (Y nozzles) for discharging the Y ink. In other words, the C nozzle row, the M nozzle row, and the Y nozzle row are formed to be deviated from each other in a tangential direction thereof, and thereby configure the chromatic nozzle row 62b as a whole. The C nozzle row, the M nozzle row, and the Y nozzle row have the same number of nozzles Nz, respectively.
Furthermore, each of the C nozzle row, the M nozzle row, and the Y nozzle row is a part of the K nozzle row 62a and configures a nozzle group G1, G2, and G3 with a portion forming a pair. Here, the term “forming a pair” means that these are in the same range in the sub-scanning direction. Specifically, the C nozzle row and a portion forming a pair with the C nozzle row which is a part of the K nozzle row 62a configure a nozzle group G1. Similarly, the M nozzle row and a portion forming a pair with the M nozzle row which is a part of the K nozzle row 62a configure a nozzle group G2, and the Y nozzle row and a portion forming a pair with the Y nozzle row which is a part of the K nozzle row 62a configure a nozzle group G3.
In the print head 62, a region (band) having a constant width on the print medium in the sub-scanning direction can be printed by each of the nozzle groups G1, G2, and G3. That is, printing using each of the nozzle groups G1, G2, and G3 is performed on one band, and thereby a color image using CMYK is completed in the one band. The width of the one band is equivalent to the length of one of the nozzle groups (the length in the sub-scanning direction).
In the print head 62, for each nozzle, a piezoelectric element for ejecting an ink droplet (dot) from the nozzle is provided. The piezoelectric element is deformed when the driving signal is applied, and ejects a dot from a corresponding nozzle. The transport mechanism 57 (
Driving of a carriage motor 58 is controlled to ASIC56, and thereby a carriage 60 (and the print head 62) moves along the main scanning direction, and the ASIC56 causes an ink to be discharged from each nozzle to the print head 62 at a predetermined timing along the movement. Accordingly, a dot adheres to the print medium and an image to be printed is reproduced on the print medium. The printer 50 further includes an operation panel 59. The operation panel 59 includes a display unit (for example, a liquid crystal panel), a touch panel formed in the display unit, and various buttons and keys, and receives an input from an user or displays a required UI screen on the display unit.
An array of nozzles of the print head 62 is not limited to the array illustrated in
Here, it is described that the CPU 11 performs the flowchart using the printer driver 13 (print control program). Based on the flowchart, it is assumed that a user operates the operation unit 40, and thereby any application software is activated and any image to be printed is selected.
Then, the user operates the operation unit 40 and displays a UI screen for setting a print condition on the display 30. In this state, the printer driver 13 receives the print condition. That is, the printer driver 13 receives a selection of the print conditions when causing the printer 50 to print an image to be printed according to a user input through the UI screen. Specifically, the printer driver 13 receives various print conditions such as, besides a selection of whether it is a color printing or a monochrome printing, a print mode (print speed), a type of print media, orientation of printing, assignment for a paper, necessity of two-sided printing, and the like according to a user input.
In step S100, an image data acquisition unit 13a receives any print executing instruction by a user, and acquires image data (hereinafter, referred to as input image data), where the image to be printed is represented, according to the print executing instruction. The input image data acquires a HDD 20, a memory card mounted on a connector for external connection which is not shown, and the like from a predetermined storage region. Here, as input image data, image data having color information for every pixel are acquired. The color information is data representing each gradation value (for example, 0 to 255 gradations) of red (R), green (G), and blue (B), for example.
In step S110, the image data processing unit 13c selects one of a color printing and a monochrome printing. The selection is performed along the print condition received according to a user's input through the UI screen. Here, it is assumed that the monochrome printing is selected by the user, and accordingly, in the step S110, the image data processing unit 13c selects the monochrome printing. Since processing where the color printing is selected and which causes an image to be printed to be color-printed by the printer 50 has been known, description thereof will be omitted in the embodiment.
In step S120, the image data processing unit 13c performs an image processing on input image data. The image processing performed in the step S120 means processing which includes steps until at least region determination to be described below (step S130) is executable among steps of generating print data from the input image data. For example, the image data processing unit 13c performs resolution conversion processing, which matches the number of pixels of the input image data to the print resolution of the printer 50, and a color conversion processing which converts the gradation (RGB value) of each pixel of the input image data to the gradation of an ink color system used by the printer 50. Here, since the monochrome printing is selected, the color conversion processing converts the gradation of each pixel of the input image data to the gradation of a K ink only, for example, a gradation which is equivalent to brightness obtained from RGB values of each pixel using a known conversion formula into the gradation of the K ink (for example, 0 to 255 gradations). Accordingly, the input image data are converted into image data having the gradation of the K ink (the amount of K ink) in each pixel.
Next, the image data processing unit 13c performs halftone (HT) processing on image data after the color conversion processing. The HT processing is processing which converts to image data deciding formation or non-formation of dot (dot on or dot off) in each pixel, and is performed using a dither method or an error diffusion method. Image data after the color conversion processing and image data after the HT processing are an example of the monochrome image data representing a monochrome image. Alternatively, input image data acquired by the image data acquisition unit 13a may be referred to as the monochrome image data representing the monochrome image.
In step S130, the region determination unit 13b determines the presence or absence of a region where the amount of use of the K ink indicated by the monochrome image data is equal to or higher than a predetermined threshold value (hereinafter, referred to as a K high-density region). Specifically, the region determination unit 13b divides monochrome image data into a plurality of regions, and directly or indirectly derives the amount of use of the K ink in each region. For example, when image data after the HI processing are set to an object of region determination, a rate of dot-on pixels in each region is calculated, and whether or not the region is the K high-density region is determined according to whether or not the rate is equal to or higher than a predetermined threshold value TH. The time when the image data after the HT processing are set to the object of region determination, at least until HT processing is included in the image processing by the step S120.
The region determination unit 13b branches processing by whether or not the region is a K high-density region for each region obtained by dividing the monochrome image data (step S140). In this case, when an object region is a K high-density region (“Yes” in step S140), the procedure proceeds to step S150, and on the other hand the procedure proceeds to step S160 when the object region is not the K high-density region (“No” in step S140). Region determination in step S130 may be performed on image data after the above-described color conversion processing. In this case, the region determination unit 13b compares a total value of K ink amounts of all pixels in each region with a certain threshold value to determine presence or absence of K high-density region, or compares an average value of the K ink amounts of all pixels in each region with a certain threshold value to determine presence or absence of the K high-density region. The time when the image data after the above-described color conversion processing is regarded as an object of region determination, at least until color conversion processing is included in image processing by the step S120.
In step S150, with regard to a region which is an object at that time, the image data processing unit 13c generates print data and the color dot control unit 13d performs color dot disposition processing. For example, when the color conversion processing in the step S120 is completed, the image data processing unit 13c performs the HT processing on the image data after the color conversion processing, and generates print data by performing rasterization processing which generates print data sorted in an order to transfer image data after HT processing to the printer 50. According to the rasterization processing, it is determined according to the pixel position at which number of times of the main scanning (path) and by which nozzle each dot defined as the image data after HT processing are formed. Alternatively, when performing until HT processing in the step S120, the image data processing unit 13c generates print data by performing the rasterization processing on the image data after the HT processing. The print data generated in this way are data (K ink print data) for printing an image to be printed by discharge of the K ink only.
Besides, in the color dot disposition processing in the step S150, the color dot control unit 13d generates chromatic color ink print data for discharging the chromatic color ink. The chromatic color ink print data are image data of the same size as a region which is an object in the step S150, and image data where dots of a plurality of chromatic color inks (C, M, Y ink) which may be discharged by the printer 50 are disposed not to overlap with each other. The chromatic color ink print data may be what dots of each chromatic color ink are regularly or irregularly disposed so as not to overlap with each other, and the number of dots in each chromatic color ink may be the same as the others or different from the others. A method of generating the chromatic color ink print data is not particularly limited. As an example, the color dot control unit 13d may generate the print data by applying a mask M1, M2, and M3 for disposing a color dot (hereinafter, marked as a mask M1, M2, and M3) which is stored in the HDD 20 in advance.
In step S160, with regard to a region which is an object at that time, the image data processing unit 13c generates print data in the same manner as in step S150, but the color dot disposition processing by the color dot control unit 13d is not performed. That is, with regard to a region not corresponding to a K high-density region in the monochrome image data, only the K ink print data are generated as the print data, and the chromatic color ink print data are not generated. Steps S140 to S160 are repeatedly performed on every region which is an object of region determination (step S130). Processing until generation of the print data (K ink print data) is performed in step S120, and in step S150, the color dot disposition processing only may be performed. In this case, since a step S160 is unnecessary, the step S160 is simply skipped after branching of “No” at step S140.
In step S170, the image data processing unit 13c generates a print command including the print data (K ink print data, chromatic color ink print data) to send to the print command to the printer 50. The print command includes information specifying the print condition received when there is a print start instruction. As a result, the printer 50 performs printing (printing of an image to be printed under the specified print condition) based on the print command which is sent.
In addition, in
In the example of
According to the embodiment, when monochrome printing is selected by a user, the print control device performs an image formation and performs a discharge of the chromatic color ink by discharge of the K ink in a region (K high-density region) where the amount of use of the K ink is equal to or higher than a predetermined threshold value among the monochrome images indicated by the monochrome image data. Therefore, the discharged chromatic color ink is hardly noticeable on the print medium (it is hard for a user to recognize the discharged chromatic color ink). That is, it is possible to substantially eliminate the effect (a decrease in OD value) of the chromatic color ink on an image quality of a print result of the monochrome image, and to reduce a plugging of the nozzle of the chromatic color ink.
In particular, in the K high-density region reproduced to the print medium, the chromatic color inks of different colors are discharged to positions which do not overlap each other, and thereby it is possible to suppress the decrease in the OD value which is caused by an overlap between dots of the chromatic color ink, the blurring of an outline, and a deviation of hue to prevent a decrease in the image quality.
In addition, since more chromatic color ink is discharged in a region where the amount of use of the K ink is large, in a region where a so-called monochrome solid image is printed, a covering rate of the surface of the print medium by an ink is improved and the image quality is improved.
The invention is not limited to the embodiments described above, and can be embodied in various aspects without departing from the scope and spirit thereof, and, for example, the following modification example is also possible. The content with a combination of the embodiments described above and some or all of each modification example is a disclosed scope of the invention.
A threshold value used when performing region determination (step S130 of
In this case, the region determination unit 13b, with regard to one region in the monochrome image data, determines that the region is the K high-density region for all of the C, M, and Y inks (hereinafter, referred to as a third K high-density region) when a dot-on rate of the K ink (a type of the amount of use of the K ink) is equal to or higher than a threshold value TH3. On the other hand, when the dot-on rate of the K ink is equal to or higher than a threshold value TH2 and less than the threshold value TH3, the region is determined to be the K high-density region for the Y and C inks (hereinafter, referred to as a second K high-density region). Similarly, when the dot-on rate of the K ink is equal to or higher than a threshold value TH1 and less than the threshold value TH2, the region is determined to be the K high-density region for the Y ink (hereinafter, referred to as a first K high-density region), and when the dot-on rate of the K ink is less than the threshold value TH1, the region is determined not to be the K high-density region for any of the chromatic color inks.
Under such a determination, in step S150, the color dot control unit 13d generates chromatic color ink print data where dots of the C, M, and Y inks are disposed when a region which is regarded as an object at that time is the third K high-density region. On the other hand, when the region which is regarded as an object at that time is the second K high-density region, the color dot control unit 13d generates chromatic color ink print data where dots of the Y and C inks are disposed, and generates chromatic color ink print data where dots of the Y ink are disposed when the region is the first K high-density region.
In the modification example 1, determination criteria to determine whether to form dots of the chromatic color ink and dots of the K ink (a density of a black ink (the amount of use of the K ink) in each region of the monochrome image data) is different according to a type of an ink. That is, the threshold value is set according to intensity of the effect of each chromatic color ink on an appearance of the print result (the level of brightness). A chromatic color ink which has a relatively high brightness (a chromatic color ink whose dot is unlikely to be noticed) is discharged with the black ink even in a region where the amount of use of the K ink is relatively low, and a chromatic color ink which has a low brightness (a chromatic color ink whose dot is likely to be noticed) is discharged with the black ink in a region where the amount of use of the K ink is relatively high. Therefore, it is possible to realize a good balance between the ensuring of a quality of the print result of the monochrome image and the suppressing of the plugging of a nozzle of the chromatic color ink. Considering that the C and the M ink have the same brightness, relations of the threshold values TH1, TH2, and TH3 may be set to TH1<TH2=TH3.
For example, when performing description referring to
That is, the printer 50, at a timing after the nozzle rows of the chromatic color ink pass through a band corresponding to a region which is not the K high-density region (a region where a discharge of the chromatic color ink is not performed based on the chromatic color ink print data), performs the cleaning processing on the nozzle rows of the chromatic color ink which have passed through the band. As a result, when performing a monochrome printing, by combining with a discharge of the chromatic color ink based on the chromatic color ink print data, it is possible to suppress the plugging of the nozzle of the chromatic color ink the most. Each nozzle row of the chromatic color ink may not be an object of the cleaning processing whenever passing through a band corresponding to a region which is not the K high-density region, but be an object of the cleaning processing at a rate of once in a plurality of times of passing through a band corresponding to a region which is not the K high-density region. By reducing the number of times of the cleaning processing as much as possible, it is possible to improve the throughput of printing, to suppress ink consumption, and to reduce the number of times of maintenance for the waste cap.
As one of the methods that make dots of the chromatic color ink which are discharged to the print medium for the purpose of preventing the plugging of the nozzle unnoticeable, the printer driver 13 may discharge the chromatic color ink prior to the K ink when discharging the chromatic color ink to the K high-density region. That is, in a band corresponding to the K high-density region, the chromatic color ink first lands on the print medium so as to cause the K ink to land thereon.
As in an example of
As described above, the array of the nozzles of the print head 62 may be an array in which each nozzle row of C, M, Y, and K having the same number of nozzles facing the sub-scanning direction is aligned in the main scanning direction. When adopting the array, the width of the band is equivalent to the length of the nozzle row, for example, and one region of monochrome image data is equivalent to an image printed on one band. In addition, the number of paths needed to complete one band may not be particularly limited in a case of adopting the array illustrated in
As described above, the print head 62 may have a configuration (print head of a so-called line printer) where each nozzle row of the C, M, Y, and K facing the main scanning direction is aligned and fixed in the sub-scanning direction. When adopting the array, the monochrome image data may be divided into a plurality of monochrome image data in the sub-scanning direction, and thereby each of the regions may be obtained, or an entire image may be one region. In addition, when there is a region which does not correspond to the K high-density region in the monochrome image data, the printer driver 13 performs the cleaning processing on the chromatic nozzle row (each nozzle row of C, M, and Y) after a printing of one page.
A case where the computer 10 performs print control processing is described as an example above. However, the print control processing may be performed in the printer 50. That is, the CPU 51 of the printer 50 performs the firmware FW (print control program), and thereby each above-described function of the image data acquisition unit 13a, the region determination unit 13b, the image data processing unit 13c, and the color dot control unit 13d may be performed in the printer 50 and the flowcharts of
The entire disclosure of Japanese Patent Application No. 2012-252968, filed Nov. 19, 2012 is expressly incorporated by reference herein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-252968 | Nov 2012 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20080137147 | Nakano et al. | Jun 2008 | A1 |
| 20100309243 | Nakano et al. | Dec 2010 | A1 |
| 20120139980 | Ishihara | Jun 2012 | A1 |
| Number | Date | Country |
|---|---|---|
| 2008-162258 | Jul 2008 | JP |
| 2009-269321 | Nov 2009 | JP |
| 2010-184415 | Aug 2010 | JP |
| 2012-101516 | May 2012 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20140139574 A1 | May 2014 | US |
