Printing apparatus and printing method

Abstract

A printing device and a printing method capable of checking a test pattern with high precision. The printing device includes a print head having a nozzle row on which a plurality of nozzles capable of ejecting ink with respect to a print medium are arranged, and a control section that controls ejection of ink from the nozzles. The print head is capable of ejecting ink while making a relative movement with respect to the print medium in a predetermined direction, i.e., scanning. The control section controls in test printing of a TP on the print medium in such a manner that, in a case where a color difference between the color of the TP and the color of the print medium is greater than a predetermined threshold value, a first ejection amount of ink is caused to be ejected from the nozzles, and in a case where the color difference between the color of the TP and the color of the print medium is equal to or less than the threshold value, a second ejection amount of ink greater than the first ejection amount is caused to be ejected from the nozzles.

Description

TECHNICAL FIELD

[0001] The present application relates to a printing apparatus and a printing method. BACKGROUND

[0002] A technique has been disclosed in which, in an inkjet printing apparatus, a test pattern is printed on a print sheet by a print head, the test pattern is read by a scanner, and based on the read data, an abnormality of a nozzle is determined (see Patent Document 1).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-54970

[0004] However, the technique described in Patent Document 1 can result in a decrease in detection accuracy of the test pattern, and thus can result in an improper inspection, in a case where a color difference between a color of the print sheet and a color of the ink is small. Accordingly, in order to properly perform the inspection after the reading, a proper test pattern is required. SUMMARY

[0005] A printing apparatus includes a print head having a nozzle row on which a plurality of nozzles capable of ejecting a liquid with respect to a medium are arranged, and a control section for controlling ejection of the liquid from the nozzles, the print head being capable of ejecting the liquid while making a relative movement with respect to the medium in a predetermined direction, i.e., scanning, the control section, in test printing in which a test pattern is printed on the medium, performing control to cause the liquid to be ejected from the nozzles in a first ejection amount in a case where a difference between a color of the test pattern and a color of the medium is greater than a predetermined threshold value, and to cause the liquid to be ejected from the nozzles in a second ejection amount that is greater than the first ejection amount in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value.

[0006] A printing method is a printing method of a printing apparatus including a print head having a nozzle row on which a plurality of nozzles capable of ejecting a liquid with respect to a medium are arranged, the print head ejecting the liquid while making a relative movement with respect to the medium in a predetermined direction, i.e., scanning, the printing method including a test printing process of printing a test pattern on the medium, the test printing process including a first decision process of deciding an ejection amount of the liquid from the nozzles to be a first ejection amount in a case where a difference between a color of the test pattern and a color of the medium is greater than a predetermined threshold value, and a second decision process of deciding the ejection amount of the liquid from the nozzles to be a second ejection amount that is greater than the first ejection amount in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a block diagram schematically showing a configuration of an apparatus.

[0008] Figure 2 Fig. 1 is a diagram showing a specific example of a configuration including a conveyance section and a print head, etc.

[0009] Figure 3 Fig. 2 is a diagram showing the relevance of a print medium and a print head from a plan view perspective.

[0010] Figure 4 Fig. 3 is a flowchart showing the flow from printing to inspection of a TP.

[0011] Figure 5 Fig. 4 is a diagram showing an example of TP image data.

[0012] Figure 6 Fig. 5 is a diagram showing a portion of a TP enlarged.

[0013] Figure 7 Fig. 6 is a diagram showing an example of a color-by-color ejection amount table.

[0014] Figure 8 Fig. 7 is a diagram showing an example of a color-by-color pass table.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] 10... printing device; 11... control section; 11a... CPU; 11b... ROM; 11c... RAM; 12... program; 12a... print control section; 12b... reading control section; 12c... inspection section; 13... display section; 14... operation reception section; 15... communication IF; 16... conveyance section; 17... carriage; 18... print head; 19... reading section; 20... nozzle face; 21... nozzle; 22... feed shaft; 23... front drive roller; 23n... pinch roller; 24... rear drive roller; 24n... pinch roller; 25... winding shaft; 26, 26C, 26M, 26Y, 26K, 26LC, 26LM... nozzle row; 30... print medium; 40... TP image data; 41, 41C, 41M, 41Y, 41K, 41LC, 41LM... TP; 42C; 42Y... pattern; 50... color-by-color ejection amount table; 51... color-by-color pass table; D1... main scanning direction; D2... conveyance direction; D3... nozzle row direction. DETAILED DESCRIPTION

[0017] 1. Embodiment 1

[0018] Hereinafter, Embodiment 1 will be described with reference to the respective drawings. Figure 1 The respective drawings are merely examples for explaining Embodiment 1. The respective drawings are examples, and there are cases where the proportions or shapes, etc. are incorrect, do not match each other, or parts are omitted.

[0019] 1-1. Device Configuration

[0020] Figure 1 The structure of a printing device 10 according to the present embodiment will be briefly described.

[0021] The printing device 10 is a device that performs printing by ejecting ink, which is a liquid, onto a printing medium 30 (see FIG. 1) as a medium, and includes a control section 11, a display section 13, an operation receiving section 14, a communication IF 15, a conveyance section 16, a carriage 17, a print head 18, a reading section 19, and the like. IF is an abbreviation of Interface. The control section 11 includes one or more ICs, a CPU 11a, a ROM 11b, a RAM 11c, and the like as a processor, and other nonvolatile memories and the like. Figure 2 In the control section 11, the processor, that is, the CPU 11a uses the RAM 11c and the like as a work area, and performs arithmetic processing according to one or more programs 12 stored in the ROM 11b, other memories, and the like to realize various functions of a printing control section 12a, a reading control section 12b, a checking section 12c, and the like. Furthermore, the processor is not limited to one CPU, and can be a structure in which processing is performed by a plurality of CPUs, ASICs, and the like, or a structure in which processing is performed by a CPU and hardware circuits in cooperation.

[0022] The display section 13 is a unit for displaying visual information, and is constituted by, for example, a liquid crystal display, an organic EL display, and the like. The structure of the display section 13 can also include a display and a drive circuit for driving the display. The operation receiving section 14 is a unit for receiving user operations, and is realized by, for example, a physical button, a touch panel, a mouse, a keyboard, and the like. Of course, the touch panel can also be realized as a function of the display section 13.

[0023] The display section 13 and the operation receiving section 14 can be a part of the structure of the printing device 10, but can also be peripheral machines installed outside with respect to the printing device 10. The communication IF 15 is a general term for one or more IFs, and is used to connect the printing device 10 to the outside in a wired or wireless form on the basis of a predetermined network transmission protocol including a well-known communication standard.

[0024] The conveyance section 16 is a unit for conveying the printing medium 30, and includes a roller and a motor that rotates the roller and the like. The print head 18 performs printing by ejecting ink from a nozzle toward the printing medium 30 by an inkjet method. The reading section 19 is a unit for acquiring color information of the printing medium 30 and reading a printing result on the printing medium 30. The reading section 19 is also called a scanner. However, the structure of the printing device 10 can also not include the reading section 19.

[0025]

[0026] ​The carriage 17 is a mechanism that is able to move reciprocally in a predetermined direction by the power of a carriage motor that is not shown. The predetermined direction in which the carriage 17 moves corresponds to the first direction, also referred to as the main scanning direction. As shown in FIG. 1, the carriage 17 is mounted with a print head 18. Figure 2 , Figure 3 The print head 18 is a mechanism that is able to eject ink droplets onto the print medium 30. The print head 18 is mounted on the carriage 17. The print head 18 is able to move in the first direction by the power of a print head motor that is not shown.

[0027] Figure 1 The structure of the printing device 10 shown in FIG. 1 can be realized by one printer, or can be realized by a plurality of devices that are connected in a communicable manner.

[0028] That is, the actual form of the printing device 10 can be a printing system. For example, the printing system includes an information processing device that functions as the control section 11, and a printer that includes the conveyance section 16, the carriage 17, the print head 18, and the reading section 19. According to such a printing device 10 or printing system, the printing method of the present embodiment is realized.

[0029] In addition, the portion of the control section 11 that functions as the print control section 12a and the portions that function as the reading control section 12b and the inspection section 12c can be independent information processing devices.

[0030] Figure 2 A specific example of the structure of the printing device 10, mainly including the conveyance section 16 and the print head 18, is shown. In Figure 2 , the above-described configuration is shown from a perspective that is orthogonal to the conveyance direction D2 of the print medium 30.

[0031] The conveyance section 16 is provided with a feed shaft 22 at the upstream of conveyance, and is provided with a winding shaft 25 at the downstream of conveyance. The upstream and downstream of conveyance are simply referred to as the upstream and downstream. The feed shaft 22 and the long print medium 30 that is wound in a roll shape on the winding shaft 25 are tensioned in the conveyance direction D2. The print medium 30 is conveyed toward the conveyance direction D2. The print medium 30 can be paper, or can be a medium based on a material other than paper.

[0032] In the example shown in Figure 2 , the feed shaft 22 is rotated clockwise, thereby feeding the print medium 30 wound on the feed shaft 22 toward the downstream. A front drive roller 23 is provided at a position downstream of the feed shaft 22, and a rear drive roller 24 is provided at a position upstream of the winding shaft 25. The front drive roller 23 is rotated clockwise, thereby conveying the print medium 30 fed from the feed shaft 22 toward the downstream. A pinch roller 23n is provided with respect to the front drive roller 23. The pinch roller 23n pinches the print medium 30 between the pinch roller 23n and the front drive roller 23 by abutting against the print medium 30.

[0033] The rear drive roller 24 rotates clockwise, thereby conveying the print medium 30 conveyed by the front drive roller 23 toward the downstream. A nip roller 24n is provided with respect to the rear drive roller 24. The nip roller 24n nips the print medium 30 between the nip roller 24n and the rear drive roller 24 by abutting against the print medium 30.

[0034] Between the front drive roller 23 and the rear drive roller 24, a print head 18 that ejects ink from above with respect to the print medium 30 is provided. From Figure 2 As can be seen, the print head 18 is mounted on the carriage 17. The print head 18 can eject ink of a plurality of colors such as cyan (C), magenta (M), yellow (Y), black (K), light cyan (LC), light magenta (LM), and the like, for example.

[0035] Each nozzle of the print head 18 opens at a nozzle face 20 of the print head 18 opposite the print medium 30, and the print head 18 ejects or does not eject ink from the nozzle based on print data described later. The ink ejected from the nozzle is referred to as an ink droplet or a dot. The print head 18 can also be referred to as a character printing head, an inkjet head, a liquid ejection head, a print head, or the like. A print control section 12a of the control section 11 controls the ejection of ink from the nozzle.

[0036] The winding shaft 25 rotates clockwise, thereby winding the printed print medium 30 conveyed by the rear drive roller 24 on the winding shaft 25.

[0037] The feed-out shaft 22, the winding shaft 25, the rollers, and a motor or the like not shown that rotates these parts appropriately are specific examples of a conveyance section 16 that conveys the print medium 30. The number and arrangement of the rollers provided at the middle of the conveyance path for conveying the print medium 30 are not limited to Figure 2 the illustrated manner. In addition, the color of the ink ejected by the print head 18 is not limited to the above-described colors. Needless to say, a flat table or the like that supports the print medium 30 from below that receives the ink ejected from the print head 18 can also be provided between the front drive roller 23 and the rear drive roller 24. In addition, the portion of the printed print medium 30 to which printing is applied by the print head 18 can not be wound in a roll shape by the winding shaft 25, but can be cut and separated from the print medium 30 more upstream than the portion by a cutting knife not shown, and can be recycled.

[0038] In Figure 2In the example of FIG. 1, the reading section 19 is provided at a position more downstream than the carriage 17 and the print head 18 and more upstream than the rear drive roller 24. The reading section 19 optically reads the printed medium 30 after printing by the print head 18 with an image sensor and outputs image data as a result of the reading. The reading section 19 can be structured to read the printed medium 30 while moving by the carriage 17 as with the print head 18 or can be structured to read in a stationary state. Further, the reading of the reading section 19 is controlled by the reading control section 12b of the control section 11 and the result of the reading is checked by the checking section 12c of the control section 11.

[0039] Figure 3 The relevance of the printed medium 30 to the print head 18 is briefly shown from a plan view. The print head 18 mounted on the carriage 17 moves together with the carriage 17 from one end to the other end of the main scanning direction Dl (outgoing movement) and from the other end to the one end (return movement). The main scanning direction Dl intersects the conveyance direction D2. This intersection can be understood as orthogonal. Thus, Figure 2 is a view showing the print head 18 and the like from a perspective facing the main scanning direction Dl. However, for example, due to various errors in the printer as a product, the main scanning direction Dl and the conveyance direction D2 can not be strictly orthogonal.

[0040] In Figure 3 , an example of the arrangement of the nozzles 21 on the nozzle face 20 is shown. The individual small circles within the nozzle face 20 are the nozzles 21. The print head 18 receives the supply of ink of each color from an unillustrated liquid holding unit, which is called an ink cartridge or an ink tank or the like, and ejects the ink of each color from the nozzles 21, and in such a structure, the print head 18 is provided with a plurality of nozzle rows 26. The nozzle row 26 composed of the nozzles 21 ejecting C ink can be denoted as nozzle row 26C. Similarly, the nozzle row 26 composed of the nozzles 21 ejecting M ink can be denoted as nozzle row 26M, the nozzle row 26 composed of the nozzles 21 ejecting Y ink can be denoted as nozzle row 26Y, the nozzle row 26 composed of the nozzles 21 ejecting K ink can be denoted as nozzle row 26K, and the nozzle row 26 composed of the nozzles 21 ejecting LC ink can be denoted as nozzle row 26LC, and the nozzle row 26 composed of the nozzles 21 ejecting LM ink can be denoted as nozzle row 26LM. The nozzle rows 26C, 26M, 26Y, 26K, 26LC, 26LM are arranged in the main scanning direction Dl.

[0041] Each nozzle row 26 is composed of a plurality of nozzles 21, and the interval between the plurality of nozzles 21 in the conveyance direction D2, that is, the nozzle pitch, is fixed or substantially fixed. The direction in which the plurality of nozzles 21 constituting the nozzle row 26 extends is called the nozzle row direction D3. In Figure 3In the example of FIG. 1, the nozzle row direction D3 is parallel to the conveyance direction D2. In the structure in which the nozzle row direction D3 is parallel to the conveyance direction D2, the nozzle row direction D3 is orthogonal to the main scanning direction Dl. However, the structure of the nozzle row direction D3 can not be parallel to the conveyance direction D2, but can be obliquely crossed with respect to the main scanning direction Dl.

[0042] The positions of the nozzle rows 26C, 26M, 26Y, 26K, 26LC, 26LM in the conveyance direction D2 are identical to each other. The printing device 10 prints an image on the print medium 30 by combining the conveyance of the print medium 30 toward the conveyance direction D2 and the ejection of ink from the print head 18 in association with the movement of the carriage 17 in the main scanning direction Dl. The forward movement, the return movement, and the like of the carriage 17 are referred to as "scanning" or "pass" or the like. That is, the print head 18 ejects ink in association with the scanning of the carriage 17, that is, the pass. The print head 18 moves toward the main scanning direction Dl in association with the scanning of the carriage 17, which corresponds to the relative movement of the print head 18 with respect to the print medium 30.

[0043] 1-2. Test pattern printing

[0044] Figure 4 The flow from the printing of the TP to the inspection based on the TP of the nozzle 21, which is performed by the control section 11 according to the program 12, is shown by a flowchart. TP is an abbreviation of Test Pattern. The flowchart is briefly composed of the following steps: the printing process TP (step S100), the acquisition of the reading result of the printed TP (step S200), and the inspection based on the reading result of the TP (step S300). The printing of the TP corresponds to test printing, and step S100 corresponds to a test printing process. In the flowchart, the printing of the TP is performed in the test printing process, and the inspection based on the reading result of the TP is performed in the inspection process. Figure 4 In the flowchart of FIG. 2, step S100 is divided into steps S110 to S190 for detailed illustration.

[0045] In step S110, the print control section 12a acquires image data representing the TP, that is, TP image data, from a storage of a predetermined memory or storage device or the like that is capable of communicating with the control section 11. For example, the TP image data is image data in a bitmap form in which the color of each pixel is specified by a predetermined color specification system. For example, the color specification system referred to here is various color specification systems such as an RGB (red, green, blue) color specification system, a CMYK color specification system, and the like.

[0046] In step S120, the reading control section 12b acquires color information of the print medium 30. The reading control section 12b acquires the color information by the reading section 19 detecting the RGB value of the leading end portion of the print medium 30 on the downstream side in the conveyance direction D2. The color information here is, for example, information expressed by the RGB (red, green, blue) color system, the CMYK color system, or the like. The reading control section 12b outputs the acquired color information to the print control section 12a.

[0047] In step S130, the print control section 12a sets the print condition of the TP. The print control section 12a directly sets the print condition at the time of the usual printing desired by the user as the print condition of the TP. The usual printing desired by the user refers to a process of printing a photo, a text, a CG, or the like arbitrarily selected by the user, rather than a process of printing the TP. The user visually confirms a user interface (UI) screen displayed by the display section 13 and operates the operation accepting section 14, so that the print condition for the usual printing can be set. The print condition includes, for example, print quality.

[0048] The print quality, for example, prompts the user with options of high definition, ordinary, fast, and the like in terms of senses, and the print control section 12a sets, in accordance with the selection of the print quality, each item necessary in the print execution, such as the moving speed of the carriage 17, the conveyance speed of the conveyance section 16, the waveform of the drive signal for driving the nozzle 21, and the driving period of the nozzle 21 in a pass. In addition, an initial setting is prepared in the print condition, and in the case where the user does not particularly change the initial setting, the print control section 12a applies such an initial setting to the print of the TP or the usual printing, or the like.

[0049] The execution order of step S110, step S120, and step S130 can be different from the order described in the flowchart, and each step can be performed substantially at the same time. Figure 4

[0050] In step S140, the print control section 12a generates print data for printing the TP from the TP image data. The print control section 12a performs a predetermined image processing, such as a color conversion process and a halftone process, as necessary, on the TP image data, thereby generating print data that specifies the ink ejection (dot opening) or non-ejection (dot closing) of each pixel and each ink color. As exemplified in FIG. 2, if the print head 18 uses a plurality of colors of ink as a premise, the print control section 12a generates, in step S140, print data that specifies the dot opening / closing of each pixel and each ink color, based on the TP image data. Figure 3

[0051] Figure 5 ​​An example of the TP image data 40 acquired in step S110 is shown. The TP image data 40 is image data that represents the TPs 41. In Figure 5 , the correspondence relationship between the TPs 41 and the main scanning direction Dl and the conveyance direction D2 is also shown in the following Figure 6 . The TPs 41 include a TP of each ink color. According to Figure 5 , the TP 41C is a TP in which the color is represented as C. Likewise, the TP 41LC is a TP in the color LC, the TP 41M is a TP in the color M, the TP 41LM is a TP in the color LM, the TP 41Y is a TP in the color Y, and the TP 41K is a TP in the color K.

[0052] In the TP image data 40, the TPs 41C, 41LC, 41M, 41LM, 41Y, 41K of each ink color are arranged in correspondence with the main scanning direction Dl, and the positions in the conveyance direction D2 are identical to each other. The TPs 41C, 41LC, 41M, 41LM, 41Y, 41K of each ink color are each a collection of a plurality of linear "patterns". In Figure 5 , one pattern is a grid line having a length direction in the main scanning direction Dl, i.e., a grid line parallel to the main scanning direction Dl. One pattern is an image printed by one of the nozzles 21 in the corresponding ink color.

[0053] Figure 6 A portion of the TPs 41 represented by the TP image data 40 is shown enlarged. Specifically, Figure 6 , a portion of the TPs 41C, 41Y is shown. The TP 41C is composed of a plurality of patterns 42C arranged at equal intervals in the conveyance direction D2, and the TP 41Y is composed of a plurality of patterns 42Y arranged at equal intervals in the conveyance direction D2. Figure 6 , for ease of understanding, a portion of each of the nozzle rows 26C, 26Y used to print the TPs 41C, 41Y is also shown. That is, each pattern 42C is arranged at an interval identical to the nozzle pitch in the conveyance direction D2 in a manner that one pattern 42C of the TP 41C is printed by one nozzle 21 constituting the nozzle row 26C. Likewise, each pattern 42Y is arranged at an interval identical to the nozzle pitch in the conveyance direction D2 in a manner that one pattern 42Y of the TP 41Y is printed by one nozzle 21 constituting the nozzle row 26Y.

[0054] In addition, in Figure 6In the example of FIG. 4, in order to easily detect each pattern 42C when checking each pattern 42C one by one, the positions of each pattern 42C in the main scanning direction Dl are kept consistent in a cycle of three, and the positions are arranged in the main scanning direction Dl with a shift. Similarly, the positions of each pattern 42Y in the main scanning direction Dl are kept consistent in a cycle of three, and the positions are arranged in the main scanning direction Dl with a shift. In this way, the linear patterns constituting the TP 41 are arranged in a step shape in a unit of three in the main scanning direction Dl for each ink color. Note that the number of steps is not limited to three if the number of steps is plural. In addition, the positions of the patterns constituting the TP corresponding to one ink color in the main scanning direction Dl can be all the same.

[0055] The print data generated in step S140 is image data in which the TP 41 represented by the TP image data 40 is expressed by the opening / closing of dots. Each pattern of each of the TPs 41C, 41LC, 41M, 41LM, 41Y, and 41K constituting each ink color is formed only by dots of the ink color corresponding thereto.

[0056] In step S150, the print control section 12a calculates the color difference between each ink color of the TP 41 in the TP image data acquired in step S110 and the color of the print medium 30 acquired in step S120, and determines whether the result is less than a predetermined threshold value. As an example of the color difference, the distance in the color space is used. The distance in the color space can convert the values in the RGB color system acquired into the values in the L*a*b* color system, and is obtained by the following formula (1).

[0057] In addition, the conversion from the values in the RGB color system into the values in the L*a*b* color system can be performed by a conversion method prescribed for a standard color space such as sRGB, AdobeRGB, or the like. Alternatively, a known interpolation operation can be used, which refers to a table in which the correspondence between the values in the RGB color system and the values in the L*a*b* color system is described, and the table is stored in advance in a predetermined memory or storage device or the like capable of communicating with the control section 11.

[0058] [Mathematical Formula 1]

[0059]

[0060] In step S150, the print control section 12a first selects one ink to be used in the printing of the TP 41, and compares the color difference between the ink color and the print medium 30 with a predetermined threshold value. Then, in the case where the color difference is greater than the predetermined threshold value, the selected ink is classified as "first ink", and in the case where the color difference is less than the predetermined threshold value, the selected ink is classified as "second ink". For example, in the case where the color of the print medium 30 is yellowish, i.e., in the case where the color difference from the C ink is greater than the threshold value and the color difference from the Y ink is below the threshold value, the C ink corresponds to the first ink and the Y ink corresponds to the second ink.

[0061] In the case where the color difference between the ink color and the print medium 30 is less than the predetermined threshold value, the print control section 12a proceeds to step S160, and in the case where it is greater than the predetermined threshold value, it proceeds to step S170.

[0062] In steps S160 and S170, the ejection amount of each ink ejected from the nozzle 21 at the time of printing the TP 41 is determined by the print control section 12a. Figure 7 An example of the respective color ejection amount table 50 for determining the ejection amount is shown. The respective color ejection amount table 50 is stored in advance in a memory or storage device or the like within or outside the printing apparatus 10 accessible by the control section 11. The respective color ejection amount table 50 is a table defining parameters that directly or indirectly determine the ejection amount of the TP of each ink color onto the print medium 30. According to the respective color ejection amount table 50, the ejection amount of each ink color is determined by the print control section 12a. Figure 7 The respective color ejection amount table 50 defines two ejection amounts for each of the ink colors, i.e., CMYKLCLM. One of the ejection amounts is the ejection amount in the case of the first ink where the color difference from the print medium 30 is greater than the threshold value, and corresponds to the first ejection amount. The other ejection amount is the ejection amount in the case of the second ink where the color difference from the print medium 30 is below the threshold value, and corresponds to the second ejection amount. As shown in Figure 7 The ejection amount of the second ink, i.e., the second ejection amount, is set to a value greater than the ejection amount of the first ink, i.e., the first ejection amount. These ejection amounts are the ejection amounts for one scan of the print head 18. However, the number of passes for printing the TP 41 is not limited to one, and can be multiple. In addition, in the Figure 7 The first ejection amount and the second ejection amount of all ink colors are common values, but can also be different depending on the ink color.

[0063] In step S150, in the case where it is determined that the color difference between the ink color and the print medium 30 is below the threshold value, the print control section 12a proceeds to step S160, and in the case where it is greater than the predetermined threshold value, it proceeds to step S170.

[0064] For example, the color of the print medium 30 is set to (R, G, B) = (245, 245, 0), and the threshold is set to 10, and a case where the ink color is (R, G, B) = (240, 240, 0) for Y ink is described in detail.

[0065] (R, G, B) = (245, 245, 0) is (L*, a*, b*) = (94, -15, 91) in the L*a*b* color system, and (R, G, B) = (240, 240, 0) is (L*, a*, b*) = (93, -15, 89) in the L*a*b* color system. Therefore, according to formula (1), the color difference is ΔE* = 2.2, which is below the threshold. Thus, in step S160, the ejection amount of the Y ink is determined to be the second ejection amount.

[0066] On the other hand, in step S150, in a case where it is determined that the color difference between the ink color and the print medium 30 is greater than the threshold, the process proceeds to step S170. In step S170, the print control section 12a determines the ejection amount of the selected ink to be the ejection amount of the first ink, i.e., the first ejection amount. Step S170 corresponds to the first determination process.

[0067] For example, the color of the print medium 30 is set to (R, G, B) = (245, 245, 0), and the threshold is set to 10, and a case where the ink color is (R, G, B) = (0, 175, 240) for C ink is described in detail.

[0068] (R, G, B) = (245, 245, 0) is (L*, a*, b*) = (94, -15, 91) in the L*a*b* color system, and (R, G, B) = (0, 175, 240) is (L*, a*, b*) = (67, -21, 44) in the L*a*b* color system. Therefore, according to formula (1), the color difference is ΔE* = 137.8, which is greater than the threshold. Thus, in step S170, the ejection amount of the C ink is determined to be the first ejection amount.

[0069] In step S180, the print control section 12a determines whether the ejection amount has been determined for all the inks to be used in printing of the TP 41. Then, in a case where the ejection amount has been determined for all the inks, the process proceeds to step S190. On the other hand, in a case where the ejection amount is not determined for some of the inks, one of the inks is newly selected, and the process returns to step S150, and the above-described operation is repeated.

[0070] In the case of proceeding to step S190, the print control section 12a controls the movement of the carriage 17, the ejection of ink from the print head 18, and the like in accordance with the print data generated in step S140 and the ejection amounts decided in steps S160 and S170, in accordance with the print conditions set in step S130, thereby printing the TP41 onto the print medium 30. Specifically, the print control section 12a controls the ejection amounts of the second ink, which has a small color difference from the print medium 30, to be larger than the ejection amounts of the first ink, which has a large color difference from the print medium 30, when printing the TP41 onto the print medium 30. Thus, the TP41 printed with the second ink can be printed darker. In the above example, the nozzle row 26C ejecting the C ink as the first ink corresponds to the first nozzle row, and the nozzle row 26Y ejecting the Y ink as the second ink corresponds to the second nozzle row. In addition, the TP41C printed with the first ink corresponds to the first test pattern, and the TP41Y printed with the second ink corresponds to the second test pattern.

[0071] Next, steps S200 and S300 will be briefly described.

[0072] In step S200, the reading control section 12b causes the reading section 19 to perform reading on the print medium 30 after the TP41 is printed in step S100 by controlling the reading section 19, and acquires image data as a reading result from the reading section 19. Of course, the conveyance section 16 performs necessary conveyance in order for the reading section 19 to read the printed print medium 30.

[0073] However, in step S200, it is sufficient if the reading result of the printed print medium 30 can be acquired. Thus, the user can also be allowed to read the print medium 30 printed with the TP41 by an external scanner, and the printing device 10 can acquire the reading result thereof via the communication IF 15.

[0074] In step S300, the inspection section 12c inspects the state of ejection of ink from the nozzles 21 of the print head 18 based on the image data acquired as a reading result in step S200. The state of ejection of ink is classified into normal and abnormal. The abnormality refers to ejection failure in which a dot cannot be ejected, and a dot position deviation in which the dot landing position deviates from the ideal position. The inspection section 12c analyzes the image data, and detects each pattern for each ink color and each nozzle 21. Then, by determining the density, position, and the like of each pattern, the inspection section 12c inspects whether each nozzle 21 is normal or abnormal, and saves the inspection result as data.

[0075] The above, Figure 4 the flowchart ends.

[0076] According to the present embodiment, the print control section 12a, in the test printing of the TP 41, ejects the first ejection amount of ink in a case where the color difference between the TP 41 and the print medium 30 is greater than a threshold value, and ejects the second ejection amount of ink, which is greater than the first ejection amount, in a case where it is below the threshold value. As a result, in a case where the colors of the TP 41 and the print medium 30 are close to each other, the ejection amount of ink increases, the area of the dot of the pattern formed becomes large, and thus the pattern is formed to be darker, and therefore, it is possible to improve the detection accuracy at the time of inspection. Specifically, when inspecting the TP printed with the second ink, which has a small color difference from the print medium 30, based on the reading result, it is difficult to accurately determine the position of the pattern and the like, and thus it is not possible to accurately determine whether the nozzle 21 is normal or abnormal, but if the TP 41 printed in step S100 of the present embodiment is used, it is possible to accurately inspect each of the nozzles 21.

[0077] In addition, according to the present embodiment, in the TP 41, the plurality of linear patterns are arranged in a stepped manner in a plurality of segments, and thus even if the printed pattern bleeds, it is possible to suppress the mutual interference between the adjacent patterns.

[0078] Further, in the present embodiment, in the TP 41 in which the plurality of linear patterns are arranged in a stepped manner, the number of segments of the TP printed with the first ink and the number of segments of the TP printed with the second ink are equal, but the number of segments of the TP printed with the second ink can be made greater than the number of segments of the TP printed with the first ink. According to this configuration, by making the number of segments of the TP formed with the second ejection amount, in which bleeding is likely to occur, greater, it is possible to make the interval between the adjacent patterns long, and it is possible to suppress the influence of bleeding.

[0079] 2. Embodiment 2

[0080] Hereinafter, the embodiment 2 will be described. Further, for the same configuration as that of the embodiment 1, the same reference numerals are used, and the repeated description will be omitted.

[0081] In the embodiment 2, instead of the each-color ejection amount table 50 of Figure 7 , an each-color pass table 51 shown in Figure 8 is referred to.

[0082] In Embodiment 2, in step S160 or step S170, the print control section 12a refers to the pass number table 51 for each color to determine the number of scans of the carriage 17, that is, the number of passes. Specifically, the print control section 12a sets the number of passes when printing TP with the second ink for which the color difference from the print medium 30 is below the threshold value to be more than the number of passes when printing TP with the first ink for which the color difference from the print medium 30 is more than the threshold value. At this time, which of the first ink and the second ink is more in terms of the amount of ink ejected in one pass can be either, but in terms of the total amount of ejection, the second ink is set to be the one that is more. Here, the total amount of ejection obtained by multiplying the number of passes of the first ink by the amount of ejection in one pass corresponds to the first ejection amount, and the total amount of ejection obtained by multiplying the number of passes of the second ink by the amount of ejection in one pass corresponds to the second ejection amount. Further, in Figure 8 In Embodiment 2, in step S160 or step S170, the print control section 12a refers to the pass number table 51 for each color to determine the number of scans of the carriage 17, that is, the number of passes. Specifically, the print control section 12a sets the number of passes when printing TP with the second ink for which the color difference from the print medium 30 is below the threshold value to be more than the number of passes when printing TP with the first ink for which the color difference from the print medium 30 is more than the threshold value. At this time, which of the first ink and the second ink is more in terms of the amount of ink ejected in one pass can be either, but in terms of the total amount of ejection, the second ink is set to be the one that is more. Here, the total amount of ejection obtained by multiplying the number of passes of the first ink by the amount of ejection in one pass corresponds to the first ejection amount, and the total amount of ejection obtained by multiplying the number of passes of the second ink by the amount of ejection in one pass corresponds to the second ejection amount. Further, in

[0083] According to the present embodiment, in the case where the color of TP 41 has a color difference from the print medium 30 that is below the threshold value, the print control section 12a increases the amount of ejection of ink by increasing the number of scans of the carriage 17 when printing TP 41, as compared to the case where the color difference is more than the threshold value. According to this configuration, the total amount of ejection of ink is increased by increasing the number of scans, and therefore, it is possible to make the printing of TP 41 more resistant to the influence of bleeding by increasing the amount of ejection in one ejection.

[0084] 3. Other Embodiments

[0085] The present embodiment is not limited to the above-described manner.

[0086] For example, in the above-described embodiments, the configuration is shown in which the color information of the print medium 30 in step S120 is read by the reading section 19, but the present embodiment is not limited to this configuration. A sensor for acquiring color information that is different from the reading section 19 can be provided. Further, the color information that is measured can be acquired via the communication IF 15, or can be input by the user via the operation accepting section 14.

[0087] The print apparatus 10 can not be the so-called serial inkjet printer in which the print head 18 is mounted on the carriage 17 that moves in the main scanning direction D1 as described in the above-described embodiments.

[0088] For example, a so-called line-type inkjet printer in which ink ejection is performed by a print head 18 having nozzle rows 26 of each ink color, the nozzle rows 26 extending in a main scanning direction Dl intersecting the conveyance direction D2, and the nozzle row length being able to cover the width of the print medium 30, can also be assumed. In the line-type inkjet printer, the nozzle row direction D3 can also be understood as being parallel to the main scanning direction Dl rather than the conveyance direction D2.

[0089] The present embodiment will be described assuming that the printing apparatus 10 is a line-type inkjet printer, Figure 5 The grid lines of the TP 41, that is, the linear patterns, are printed to the print medium 30 in a direction parallel to the conveyance direction D2 rather than the main scanning direction Dl. Also, with respect to the multiple implementations of the pass of the print head 18 described above, a backfeed of the conveyance section 16 is used for the correspondence. The backfeed refers to a process in which the conveyance section 16 conveys the print medium 30 from the downstream toward the upstream. That is, during conveyance of the print medium 30 from the upstream toward the downstream, the print medium 30 passes under the print head 18, and at this time, printing of the print medium 30 is performed once. Thereafter, the conveyance section 16 performs backfeed, and feeds the portion of the print medium 30 on which printing has been performed once back to a position further upstream than the print head 18, and the conveyance toward the downstream is started again. By repeating this operation, the TP 41 can be repeatedly printed, as in the case of the line-type inkjet printer in which the TP 41 is printed in multiple passes.

[0090] In the case where the printing apparatus 10 is a line-type inkjet printer, the print medium 30 is conveyed by the conveyance section 16 during the period in which printing is performed by the print head 18, and this corresponds to relative movement of the print head 18 with respect to the print medium 30.

[0091] Needless to say, the print medium 30 can not be Figure 2 continuous paper or the like wound into a roll shape as illustrated. The print medium 30 can also be single sheets cut in units of pages or the like.

[0092] The shape of the TP 41 is not limited to Figure 5 or Figure 6 linear patterns having a length component in the main scanning direction Dl as illustrated. For example, in a serial printing apparatus in which liquid is ejected in conjunction with scanning of a carriage, a test pattern or the like for correcting an error between an ink landing position at a forward scan and an ink landing position at a return scan of the carriage can also be applied to the present application. In this case, in the step S300, the difference between the ink landing position at the forward scan and the ink landing position at the return scan is detected by the inspection section 12c on the basis of the reading result obtained in the step S200.

[0093] The shape of the TP 41 is not limited toFigure 5 or Figure 6 the stepped pattern in which the sections in the main scanning direction D1 and the conveyance direction D2 are staggered. However, forming the stepped pattern enables the distance between the sections to be separated, and enables a pattern to be generated in which even if bleeding occurs, the reading accuracy is difficult to be affected, so it is also possible to print the stepped pattern only in a place where bleeding is likely to occur due to an increase in the amount of ejection.

[0094] The shape of the TP41 is not limited to Figure 5 or Figure 6 all of the inks are the same shape. For example, in the TP printed with the first ink, the straight line pattern can be arranged so as not to be staggered in the main scanning direction D1 and to be staggered only in the conveyance direction D2, and in the TP printed with the second ink, the straight line pattern can be arranged so as to be staggered in the main scanning direction D1 and the conveyance direction D2. By adopting such a configuration, for the second ink, which has a larger amount of ejection and is more likely to bleed than the first ink, it is possible to suppress a decrease in the detection accuracy due to interference with the adjacent patterns before and after caused by bleeding.

[0095] The configuration of the TP41 is not limited to Figure 5 the plurality of TPs in which the ink colors are different are arranged in the main scanning direction D1. For example, the TPs for each color or each plurality of colors can be arranged in the conveyance direction D2.

[0096] Further, in the present embodiment, the distance in the color space is calculated as the color difference using the L*a*b* color system, but the method of calculating the color difference is not limited to this method. For example, the Euclidean distance in the color space in the RGB color system or the like can be calculated. In this case, it is appropriate to compare the color difference with a proper threshold value corresponding to the method of calculating the color difference.

Claims

1. A printing device characterized by comprising: Possessing: a print head having a nozzle row on which a plurality of nozzles capable of ejecting a liquid with respect to a print medium are arranged; and a control section that controls ejection of the liquid from the nozzles, the print head is capable of ejecting the liquid while making a relative movement with respect to the medium toward a predetermined direction, that is, scanning, the control section, in a test printing in which a test pattern is printed to the medium, controls in the following manner: in a case where a difference between a color of the test pattern and a color of the medium is greater than a predetermined threshold value, causes the liquid to be ejected from the nozzles in a first ejection amount, in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value, causes the liquid to be ejected from the nozzles in a second ejection amount that is greater than the first ejection amount.

2. The printing apparatus according to claim 1, wherein the control section, in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value, increases the ejection amount of the liquid by increasing a number of scans of the print head when the test pattern is printed, as compared with a case where the difference is greater than the threshold value.

3. The printing apparatus according to claim 1 or 2, wherein the control section, in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value, increases the ejection amount of the liquid per one scan of the print head, as compared with a case where the difference is greater than the threshold value.

4. The printing apparatus according to claim 1 or 2, wherein the test pattern is printed by the liquid ejected from each of the nozzles, and includes a plurality of linear patterns having a length component in a first direction intersecting an extension direction of the nozzle row.

5. The printing apparatus according to claim 4, wherein the plurality of linear patterns are arranged in a stepped manner in a plurality of segment units.

6. The printing apparatus according to claim 5, wherein the control section, in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value, increases a number of segments in the first direction, as compared with a case where the difference is greater than the threshold value.

7. The printing apparatus according to claim 5 or 6, wherein the print head includes a first nozzle row and a second nozzle row arranged in the first direction, as the nozzle row, the control section prints, as the test pattern, a first test pattern printed with the first ejection amount from the first nozzle row and a second test pattern printed with the second ejection amount from the second nozzle row, arranged in the first direction, the linear patterns constituting the first test pattern and the second test pattern are respectively arranged in a stepped manner in a plurality of segment units, the second test pattern has a greater number of segments in the first direction than the first test pattern.

8. A printing method characterized by, a printing method of a printing apparatus, The printing apparatus includes a print head having a nozzle row in which a plurality of nozzles capable of ejecting a liquid with respect to a medium are arranged, and the print head ejects the liquid in conjunction with a relative movement toward a predetermined direction, i.e., scanning, with respect to the medium, The printing method includes a test printing process of printing a test pattern on the medium, The test printing process includes: a first decision process of deciding an ejection amount of the liquid ejected from the nozzles to be a first ejection amount in a case where a difference between a color of the test pattern and a color of the medium is greater than a predetermined threshold value, and a second decision process of deciding the ejection amount of the liquid ejected from the nozzles to be a second ejection amount that is greater than the first ejection amount in a case where the difference between the color of the test pattern and the color of the medium is below the threshold value.

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