JP6135045B2 - Printing apparatus, correction value acquisition method, and printing apparatus manufacturing method - Google Patents

Description

  The present invention relates to a printing apparatus, a correction value acquisition method, and a printing apparatus manufacturing method.

  Many printers (printing apparatuses) that can express a plurality of colors are used. In such a color printer, density calibration processing is performed to improve color reproducibility. The density calibration process is a process in which the printer prints a test pattern on a sheet of paper, and corrects the printer to print an image of the target density based on the difference between the density measurement result of the test pattern and the target density. .

  In addition, in a printer that forms dots of a plurality of sizes, an error in the ink discharge amount may differ for each dot size. Therefore, a printer has been proposed in which error information is stored for each dot size and the ink discharge amount is corrected for each dot size to further improve the color reproducibility (see, for example, Patent Document 1).

JP 2003-182120 A

  Print data for the printer to print an image is created based on a “dot generation rate table” in which input tone values representing the density of pixels on the medium and dot generation rates are associated with each other. In a printer that prints images on a plurality of types of media, a dot generation rate table is stored for each type of medium according to the characteristics of each medium. Therefore, if a method for printing a test pattern with print data created based on a dot generation rate table corresponding to each medium is executed during density calibration processing, the test pattern must be printed for each medium. Will not be. As a result, the processing becomes complicated as the types of media increase.

  Accordingly, an object of the present invention is to simplify the density calibration process.

The main invention for solving the above problems is based on a table that specifies a dot generation rate for each dot size of dots formed on a medium and an input tone value associated with the dot generation rate for each dot size. A printing apparatus that prints print data on a medium, and ejects ink toward the medium, forms a plurality of dots on the medium, and ejects ink from the head to perform printing. A control unit for performing a test pattern for each dot size on a first medium and correcting the table based on the table used for printing on the first medium and the test pattern reading result The print data is printed on the first medium based on the input gradation value, the table used for printing on a second medium different from the first medium, and the test Based on said input tone values corrected based on the turn of the reading result, and a control unit that performs printing of the print data to the second medium is a printing apparatus, characterized in that it comprises a.
Other features of the present invention will become apparent from the description of this specification and the accompanying drawings.

1 is a block diagram illustrating an overall configuration of a printing system. FIG. 2A is a schematic perspective view of the printer, and FIG. 2B is a diagram illustrating an optical sensor. FIG. 3A is a flow showing print data creation processing, and FIG. 3B is a diagram for explaining a correction value table in which correction values are associated with input gradation values. FIG. 4A is a diagram illustrating a dot generation rate table, and FIG. 4B is a diagram illustrating ON / OFF determination of large dots. 5A and 5B are diagrams for explaining density calibration processing of a comparative example. 6 is a flow of density calibration processing in the first embodiment. 7A to 7C are diagrams for explaining test patterns. FIG. 8A is a graph showing the relationship between the density value obtained by normalizing the reading result and the target density value, and FIG. 8B is a diagram for explaining the correction gradation value table and the correction dot number table. It is a figure explaining a mode that the correction value with respect to an input gradation value is acquired. FIG. 10 is a diagram for explaining density calibration processing in the second embodiment. FIG. 11A and FIG. 11B are diagrams for explaining density calibration processing in the third embodiment.

=== Summary of disclosure ===
At least the following will become apparent from the description of the present specification and the accompanying drawings.

That is, based on a table that specifies the dot generation rate for each dot size of dots formed on the medium and the input tone value associated with the dot generation rate for each dot size, print data is printed on the medium. A printing apparatus that performs ejection by ejecting ink toward the medium and forming the dots of a plurality of sizes on the medium; and a controller for performing printing by ejecting ink from the head, A test pattern for each dot size is printed on a first medium, based on the table used for printing on the first medium, and the input tone value corrected based on the read result of the test pattern The printing data is printed on the first medium, and the table used for printing on the second medium different from the first medium is supplemented based on the reading result of the test pattern. Based on the has been the input tone value, and a control unit that performs printing of the print data to the second medium is a printing apparatus, characterized in that it comprises a.
According to such a printing apparatus, it is possible to correct the input tone value corresponding to the table of each medium without printing a test pattern for each type of medium, thereby simplifying the correction process. it can.

In the printing apparatus, the corrected table specifies, for each dot size, a correspondence relationship in which the input gradation value and the correction gradation value are associated with each other based on the reading result of the test pattern. The control unit acquires the corrected gradation value corresponding to the input gradation value based on the correspondence relationship, and sets the dot generation rate specified from the corrected gradation value based on the table for each dot size. And printing on the medium based on the dot generation rate for each dot size.
According to such a printing apparatus, the input gradation value can be corrected in correspondence with the table of each medium without printing a test pattern for each type of medium.

In this printing apparatus, the control unit acquires a first correspondence relationship in which the dot generation rate and the correction dot generation rate in the table are associated for each dot size based on the correspondence relationship, and prints. The second is obtained by associating the input tone value with a value obtained by converting the dot generation rate of each size in the input tone value into a dot generation rate of a predetermined size based on the table for the medium on which the image is performed. The dot generation rate of each size at a certain input gradation value is corrected to the corrected dot generation rate based on the table for the medium on which the printing is performed and the first correspondence relationship. After that, the corrected dot generation rate of each size is converted into the dot generation rate of the predetermined size, and the dot generation rate of the predetermined size closest to the converted dot generation rate is selected from the second correspondence relationship. And, the input grayscale value corresponding to the dot generation rate of the predetermined size selected, to the correction value of the certain input grayscale value.
According to such a printing apparatus, the input gradation value can be corrected in correspondence with the table of each medium from the corrected gradation value for each dot size with respect to the input gradation value.

In this printing apparatus, the control unit determines the correction gradation value of each dot size in a certain input gradation value based on the table for the medium on which printing is performed and the correspondence relationship. A weighted average value is obtained by a ratio between the total dot generation rate and the dot generation rate of each size in the input gradation value, and the weighted average value is used as a correction value for the certain input gradation value.
According to such a printing apparatus, the input gradation value can be corrected in correspondence with the table of each medium from the corrected gradation value for each dot size with respect to the input gradation value.

In this printing apparatus, the first medium is a medium that uses, for printing, a table having a maximum amount of ink that can be ejected per unit area among a plurality of tables used for printing on the medium.
According to such a printing apparatus, it is possible to suppress the bleeding of the ink and the waviness of the medium, and it is possible to appropriately read the test pattern.

In this printing apparatus, the control unit performs each of a first mode in which a table used for printing on the first medium is a first table and a second mode that is a second table. , Printing is performed by ejecting ink from the head, and the test pattern is set for each dot size depending on whether the first mode is set or the second mode is set. At least one of the upper limit value of the input tone values and the interval of the input tone values for each dot size are different.
According to such a printing apparatus, wasteful consumption of media and ink can be suppressed.

A table used for printing of a printing apparatus including a head that forms dots of a plurality of sizes on the medium by ejecting ink toward the medium, and generating dots for each dot size of the dots formed on the medium A correction value acquisition method for correcting a table for specifying a rate and an input gradation value associated with a dot generation rate for each dot size, wherein the head uses a first test pattern for each dot size as a first pattern. Printing on the medium; obtaining a correction value of the table used for printing on the first medium based on the result of reading the test pattern; and second based on the result of reading the test pattern. Obtaining a correction value of the table used for printing on the medium.
According to such a correction value acquisition method, the correction value of the input gradation value can be acquired in correspondence with the table of each medium without printing a test pattern for each type of medium, thereby simplifying the processing. Can be

A printing apparatus including a head that forms dots of a plurality of sizes on the medium by ejecting ink toward the medium, the dot generation rate for each dot size of the dots formed on the medium, and the dot size A method for manufacturing a printing apparatus that prints print data on a medium using a table that specifies input gradation values associated with each dot generation rate, and is used for printing on a first medium. A test pattern for each dot size is printed on the first medium by the first printing device whose table is the first table, and the test pattern printed by the first printing device is read. A plurality of tables used for printing of the first printing apparatus, each table being corrected, and used for printing on the first medium. A test pattern for each dot size is printed on the first medium by a second printing device whose second table is a second table, and a result of reading the test pattern printed by the second printing device A plurality of tables used for printing of the second printing apparatus, and correcting the table for each medium on which printing is performed, wherein the test pattern is the first printing apparatus. Of the input gradation value for each dot size and the interval between the input gradation values for each dot size, depending on whether the printing is performed by the second printing apparatus. This is a method of manufacturing a printing apparatus in which at least one of them is different.
According to such a manufacturing method of a printing apparatus, the correction value of the input gradation value can be acquired in correspondence with the table of each medium without printing a test pattern for each type of medium. Can be simplified. In addition, wasteful consumption of media and ink can be suppressed.

=== Printing system ===
The embodiment will be described by taking a printing system in which an inkjet printer (hereinafter referred to as a printer) and a computer are connected as an example.
FIG. 1 is a block diagram showing the overall configuration of the printing system. FIG. 2A is a schematic perspective view of the printer 1, and FIG. 2B is a diagram illustrating the optical sensor 51. The printer 1 includes a controller 10, a transport unit 20, a carriage unit 30, a head unit 40, and a detector group 50. The printer 1 is communicably connected to the computer 60, and print data for causing the printer 1 to print an image is created by a printer driver installed in the computer 60 and transmitted to the printer 1. The printer driver is stored in a CD-ROM or the like, or can be downloaded via the Internet.

  A controller 10 in the printer 1 is for performing overall control in the printer 1. The interface unit 11 transmits and receives data to and from the computer 60 that is an external device. The CPU 12 is an arithmetic processing device for performing overall control of the printer 1, and controls each unit via the unit control circuit 14. The memory 13 (storage unit) is for securing an area for storing a program of the CPU 12, a work area, and the like.

The transport unit 20 feeds the paper S (corresponding to a medium) to a printable position and transports the paper in the transport direction. The medium on which the printer 1 prints an image is not limited to paper, and may be, for example, cloth or film.
The carriage unit 30 is for moving the head 41 mounted on the carriage 31 in a moving direction that is a direction intersecting the transport direction of the paper S. Note that the intersecting direction is generally an orthogonal direction.

  The head unit 40 is for ejecting ink toward the paper S and printing an image, and has a head 41. A number of nozzles for ejecting ink are provided on the lower surface (not shown) of the head 41, and a nozzle row is formed for each color of ejected ink. For example, a black nozzle row that discharges black ink K, a cyan nozzle row that discharges cyan ink C, a magenta nozzle row that discharges magenta ink M, a yellow nozzle row that discharges yellow ink Y, and the like are formed on the lower surface of head 41. Has been. In each nozzle row, a large number of nozzles are arranged at predetermined intervals in the transport direction. The ink ejection method from the nozzle may be a piezo method in which ink is ejected from the nozzle by expanding and contracting the ink chamber communicating with the nozzle by applying a voltage to the driving element (piezo element), or using a heating element. Alternatively, a thermal method in which bubbles are generated in the nozzle and ink is ejected from the nozzle by the bubble may be used.

  Each nozzle provided in the head 41 can form dots of a plurality of sizes. That is, each nozzle can eject various amounts of ink in accordance with a plurality of sizes of dots. In this embodiment, each nozzle can form dots of three types (large dots, medium dots, and small dots).

  The detector group 50 is for monitoring the situation in the printer 1 and outputting the detection result to the controller 10. For example, the detector group 50 includes an optical sensor 51 as shown in FIG. 2B. The optical sensor 51 detects the distance from the nozzle surface of the head 41 to the paper S and the width of the paper S.

  The optical sensor 51 includes a light emitting unit 511 and a light receiving unit 512. The light emitting unit 511 is for irradiating the paper S with light, and examples thereof include a light emitting diode (LED), a laser diode, an incandescent light bulb, and the like. The irradiation area when the light irradiated from the light emitting unit 511 is focused on the surface of the paper S is called a spot, and the spot diameter is called a spot diameter. The light receiving unit 512 is a photoelectric conversion element that receives light reflected by the paper S out of light emitted from the light emitting unit 511 toward the paper S and generates a current according to the received light amount. Examples of the light receiving unit 512 include a photodiode and a phototransistor. Further, as shown in FIG. 7A to be described later, the optical sensor 51 is attached to the carriage 31 and thus can be moved in the moving direction. Further, since the optical sensor 51 is attached to the downstream side in the transport direction from the head 41, the head 41 is provided. Can move over the printed image.

  The amount of reflected light (the intensity of the reflected light) received by the light receiving unit 512 of the optical sensor 51 varies depending on the color density at the reflection position of the paper S. Therefore, the density of the image can be detected based on the result of the light emitting unit 511 irradiating light toward the image printed on the paper S and the light receiving unit 512 receiving the reflected light from the image. That is, the optical sensor 51 can function as an image density detector.

  In the printer 1 having such a configuration, the controller 10 transports the paper S to the downstream side in the transport direction by the discharge operation of discharging the ink from the nozzles while moving the head 41 in the moving direction by the carriage 31. The transfer operation is repeated alternately. As a result, since dots are formed by the subsequent ejection operation at positions different from the positions of the dots formed by the previous ejection operation, a two-dimensional image is printed on the paper S.

=== Print Data Creation Processing ===
FIG. 3A is a flowchart showing print data creation processing, and FIG. 3B is a diagram for explaining a correction value table in which correction values are associated with input gradation values. Hereinafter, a process in which the computer 60 (hardware resource) creates print data according to a printer driver in the computer 60 connected to the printer 1 will be described.

  First, a controller (not shown) in the computer 60 obtains image data to be printed by the printer 1 from various application programs, and obtains data of paper on which an image is printed from the user (S001). Here, it is assumed that the type of paper on which an image is printed is “first paper S1”. Next, the controller performs resolution conversion processing (S002). The resolution conversion process is a process of converting the resolution of the acquired image data into the resolution when the printer 1 prints an image. Next, the controller performs a color conversion process (S003). The color conversion process is a process of converting image data expressed in RGB into ink color data (KCMY data) that can be ejected by the printer 1.

  The image data after the color conversion process is composed of a plurality of pixel data for each ink color. Pixel data is data relating to pixels of an image to be printed. Here, a pixel is a unit element constituting an image, and an image is formed by arranging these pixels two-dimensionally. Pixel data in the image data is data relating to dots formed on the paper S (for example, gradation values). Here, it is assumed that the gradation value indicated by the pixel data (hereinafter referred to as the input gradation value) is a value of 256 gradations (0 to 255), and the larger the input gradation value (the closer to 255), the corresponding. It is assumed that the density of the corresponding pixel is lighter as the density of the pixel is higher and the input tone value is smaller (closer to 0).

  Next, the controller performs input tone value correction processing (S004). By the way, due to an error in the amount of ink ejected from the head 41, the color output characteristics of the individual printers 1 differ. Even in the same printer, the color output characteristics may change due to changes over time. In order to correct this color output characteristic difference, the controller corrects the input tone value indicated by each pixel data in the input tone value correction processing. At that time, the controller refers to the “correction value table (FIG. 3B)” stored in the memory 13 in the printer 1. In the correction value table, each input gradation value (0 to 255) that can be used for printing image data is associated with a correction value of the input gradation value in advance.

  The correction value table is created for each ink color and for each type of paper S in density calibration processing (correction value acquisition processing) described later. In the density calibration process, the printer 1 actually prints a test pattern, and a correction value for the input gradation value is obtained based on the difference between the read result of the test pattern and the target density. For example, when a test pattern having a lighter density than the target density is printed, a gradation value higher than the input gradation value is obtained as a correction value so that the amount of ink ejected from the head 41 is increased. When a test pattern having a high density is printed, a gradation value lower than the input gradation value is obtained as a correction value so that the amount of ink discharged from the head 41 is reduced.

  For example, when the input tone value correction process is performed on black image data, the controller refers to the first paper S1 used for printing and the correction value table (FIG. 3B) corresponding to black. An input gradation value (eg, 160) indicated by pixel data is converted into a correction value (eg, 151). As described above, the controller corrects the input gradation value for all pixel data belonging to the image data of each color (KCMY).

  Next, the controller performs halftone processing (S005). The halftone process is a process of converting a high gradation input gradation value (corrected value) indicated by the pixel data into a low gradation value that can be expressed by the printer 1. Since the printer 1 of the present embodiment can form dots of three types of sizes, one pixel can be expressed with four gradations. Specifically, one pixel can be expressed by any one of “large dot formation”, “medium dot formation”, “small dot formation”, and “no dot”. Therefore, by the halftone process, the 256 gradation input gradation values indicated by the pixel data are converted into four gradation values. Hereinafter, the halftone process will be specifically described.

  FIG. 4A is a diagram illustrating a dot generation rate table, and FIG. 4B is a diagram illustrating ON / OFF determination of large dots. 4A is a graph of the dot generation rate table shown in FIG. 9 to be described later. The horizontal axis of the graph represents the input gradation value (0 to 255) indicated by the pixel data, and the left vertical axis represents dot generation. The rate (0 to 100%) is represented, and the right vertical axis represents the number of dot generations (0 to 4080). The dot generation rate at a certain input gradation value i is the number of pixels (for example, 4080) belonging to the unit area when all pixel data corresponding to the unit area on the paper S indicates the input gradation value i. It means the ratio of pixels (example: n) in which dots are formed (example: (n / 4080) × 100). Similarly, the number of dots generated for a certain input gradation value i is the number of dots formed in the unit area when all pixel data corresponding to the unit area on the paper S indicates the input gradation value i. Means. A thin solid line SD in the graph indicates a dot generation rate for small dots, a thick solid line MD indicates a dot generation rate for medium dots, and a dotted line LD indicates a dot generation rate for large dots. The dot generation rate table corresponds to a table that specifies the dot generation rate for each dot size of dots formed on the medium and the input tone value associated with the dot generation rate for each dot size. Are stored in the memory 13 (storage unit) in the printer 1 for each color and for each type of paper S. Note that the memory in the computer 60 may store the dot generation rate table.

  The left diagram in FIG. 4B shows the number of large dots generated corresponding to the input gradation value of each pixel data, the center diagram in FIG. 4B shows the threshold value of the dither matrix for large dots, and the right diagram in FIG. 4B. The figure shows the presence or absence of large dot formation. In the following, halftone processing will be described by taking black image data as an example.

  First, the controller refers to the first paper S1 used for printing and the dot generation rate table (FIG. 4A) corresponding to black, and in the input gradation value (example: 127) indicated by the black pixel data to be processed. The number of large dots generated (for example, 2d) is read. Thereafter, as shown in FIG. 4B, the controller compares the threshold corresponding to the target pixel data in the large-dot dither matrix with the number of large-dots that have been read. When the number of large dots generated (for example, 180) is larger than the threshold value (for example: 1), the target pixel data is converted into data indicating “large dot formation”.

  On the other hand, when the number of large dots generated is equal to or less than the threshold, the controller reads the number of medium dots generated (for example, 3d) in the input tone value (example: 127) indicated by the target pixel data, Compare with the threshold value of the dither matrix. When the dot generation number of medium dots is larger than the threshold value, the target pixel data is converted into data indicating “medium dot formation”. Similarly, when the dot generation number of medium dots is equal to or smaller than the threshold value, the controller calculates the dot generation number (example: 1d) and threshold value of the small dot in the input gradation value (example: 127) indicated by the target pixel data. Compare. When the number of small dots generated is larger than the threshold, the target pixel data is converted into data indicating “small dot formation”. When the number of small dots generated is equal to or less than the threshold, the target pixel data is “ It is converted into data indicating “no dot”. As described above, the controller converts all pixel data belonging to the image data of each color into 4-gradation data.

  Finally, the controller performs rasterization processing (S006). The rasterizing process is a process of rearranging the pixel data belonging to the image data in the order in which they should be transferred to the printer 1. The rearranged pixel data is transmitted to the printer 1 as print data together with other data (for example, transport amount data of the paper S, etc.).

  The printer 1 that has received the print data prints an image on the first sheet S1 based on the print data. In this print data, since the input tone value is corrected by the correction value acquired in the density calibration process, the density of the image printed by the printer 1 can be brought close to the target density, and the color reproducibility of the printer 1 can be obtained. Can be improved.

=== Density Calibration Processing: Comparative Example ===
5A and 5B are diagrams for explaining the density calibration processing of the comparative example. The printer 1 prints images on a plurality of types of paper S. Further, the dot generation rate table used in the halftone process is varied according to the characteristics of the paper S (for example, ink absorbability and color developability). For example, in the dot generation rate table for the first paper S1 in FIG. 5A, the dot generation rate LD for large dots is relatively large, whereas in the dot generation rate table for the second paper S2 in FIG. The dot generation rates SD and MD of dots and medium dots are relatively large.

  In the density calibration process of the comparative example, print data of a test pattern is created based on the dot generation rate table corresponding to each paper S, and the test pattern is printed for each type of paper S. Therefore, in the test pattern of the comparative example, three types of dots (large dots, medium dots, and small dots) are mixed. Even in the test pattern printed with the same input gradation value, the dot configuration differs depending on the type of the paper S.

  For example, in the test pattern P1 (FIG. 5A) based on the print data created in the dot generation rate table for the first sheet S1, the portion p (128) printed with the input gradation value 128 has three sizes. The dots are mixed, the dot generation rate for large dots is 2D%, the dot generation rate for medium dots is 3D%, and the dot generation rate for small dots is 1D%. On the other hand, in the test pattern P2 (FIG. 5B) based on the print data created in the dot generation rate table for the second sheet S2, large dots are formed in the portion p (128) printed with the input gradation value 128. The dot generation rate for medium dots is 4D%, and the dot generation rate for small dots is 5D%.

  In this way, by printing a test pattern for each type of paper S, that is, by printing a test pattern with print data created in the dot generation rate table of each paper S, the dot generation rate of each paper S The correction value of the input gradation value corresponding to the table can be acquired. However, as the types of paper S used in the printer 1 increase, the number of times the test pattern is printed and read increases, and the density calibration process becomes complicated. In addition, consumption of ink and paper S for printing the test pattern also increases.

  Therefore, an object of the present embodiment is to simplify the density calibration process.

=== Density Calibration Processing: Example 1 ===
FIG. 6 is a diagram illustrating a flow of density calibration processing (correction value acquisition method) according to the first embodiment. 7A to 7C are diagrams for explaining test patterns. In the density calibration process, the correction value acquisition program installed in the computer connected to the printer 1 to be processed causes the printer 1 and the computer (hardware resource) to perform each process described below, A correction value table (FIG. 3B) is created. Note that the correction value acquisition program may be recorded on a computer-readable recording medium (for example, a CD-ROM) or downloaded via the Internet. Hereinafter, the density calibration process will be described with reference to the flow of FIG.

  First, the controller 10 (corresponding to the control unit) in the printer 1 causes the head 41 to print a test pattern according to the correction value acquisition program (S101). In this embodiment, a test pattern is not printed for each type of paper S as in the comparative example, that is, a test pattern is not printed by print data created in the dot generation rate table of each paper S. A test pattern common to all sheets S is printed. For this purpose, the controller 10 causes the printer 1 to print a test pattern for each dot size. Specifically, as shown in FIG. 7A, the printer 1 has four test patterns K (S) and C (S (S), each composed of only small dots, for each nozzle row that ejects ink of each color (KCMY). ), M (S), Y (S), four test patterns K (M), C (M), M (M), Y (M) composed only of medium dots, and large dots only The four test patterns K (L), C (L), M (L), and Y (L) are printed on the first sheet S1.

  Each of the test patterns K (S) to Y (L) is a gradation pattern in which the input tone value continuously changes, and 256 patches p in which the input tone value has increased from 0 to 255 step by step. (0) to p (255) are arranged in the moving direction. Accordingly, in each of the test patterns K (S) to Y (L), the amount of ink ejected per unit area gradually increases and the density gradually increases.

  Note that the width of the patch in the conveyance direction is made larger than the spot diameter of the optical sensor 51. In addition, in the patches p (0) and p (255) located at both ends in the movement direction, the width in the movement direction is also made larger than the spot diameter of the optical sensor 51 so as not to be affected by the margin. On the other hand, in the intermediate patches p (1) to p (254), the width in the moving direction is made smaller than the spot diameter of the optical sensor 51 so that the entire width in the moving direction of the test pattern is shortened.

  Then, in order to print a test pattern for each dot size common to all sheets S, the correction value acquisition program causes the computer to create test pattern print data using the dot generation rate table shown in FIG. 7C. . The dot generation rate table shown in FIG. 7C is a table common to three types of dots, and as the input gradation value (0 to 255) increases, the dot generation rate also increases linearly in proportion. In this dot generation rate table, for example, since the dot generation rate at the input tone value 127 is 50%, the patch p (127) of the input tone value 127 in the test pattern composed of only small dots is half. Small dots are formed in the pixels. Similarly, in the patch p (127) having the input gradation value 127 in the test pattern composed only of medium dots, medium dots are formed in half of the pixels, and input in the test pattern composed only of large dots. In the patch p (127) having the gradation value 127, large dots are formed in half of the pixels.

  In this way, in this embodiment, regardless of the type of the paper S, printing is performed up to patches with a large amount of ink ejected per unit area (that is, patches with a large dot generation rate of 100%). Therefore, if the test patterns K (S) to Y (L) are printed on the paper S with a small amount of ink that can be ejected per unit area (that is, the paper S having poor ink absorbability), the ink is smeared. There is a possibility that the density of the test patterns K (S) to Y (L) cannot be read properly because the paper S undulates.

  Therefore, in this embodiment, out of a plurality of dot generation rate tables that the printer 1 uses for printing on the paper S (medium) (that is, among the dot generation rate tables stored in the memory 13), per unit area. The test patterns K (S) to Y (L) are printed on a sheet (here, the first sheet S1) that uses the dot generation rate table with the maximum amount of ink that can be ejected. By doing so, even if a patch having a large ink discharge amount per unit area is printed, it is possible to suppress the bleeding of the ink and the undulation of the paper S, and the density of the test pattern can be read appropriately. As a result, a more accurate correction value can be obtained.

  Next, the controller 10 acquires the reading results of the twelve test patterns K (S) to Y (L) printed on the first sheet S1 (S102). In this embodiment, the test patterns K (S) to Y (L) are read by the optical sensor 51 (FIG. 2B) provided on the carriage 31. Therefore, the controller 10 first aligns the positions of the optical sensor 51 and the black test patterns K (S) to K (L) in the respective transport directions, as shown in FIG. 7A. Then, the controller 10 moves the optical sensor 51 in the moving direction by the carriage 31 so that the optical sensor 51 moves on the black test patterns K (S) to K (L). The reading results of the test patterns K (S) to K (L) are acquired. Thereafter, the controller 10 transports the first sheet S1 to the downstream side in the transport direction, and also acquires the reading results of the test patterns of other colors (CMY) by the optical sensor 51.

  In each test pattern K (S) to Y (L), the density changes in the moving direction. Therefore, the amount of light received by the light receiving unit 512 in the optical sensor 51 changes while the optical sensor 51 moves on each test pattern. That is, for each test pattern, the controller 10 reads the 256 patches p (0) to p (255) constituting each test pattern, that is, the reflection from each patch p (0) to p (255). Get the amount of light.

  In this embodiment, after that, the controller 10 in the printer 1 transmits the reading results (the amount of reflected light) of each test pattern K (S) to Y (L) to the computer, and the computer is based on the reading result of each test pattern. Then, a correction value for the input gradation value is obtained.

When a controller (not shown, corresponding to a control unit) in the computer acquires the reading results of the test patterns K (S) to Y (L) from the printer 1, first, the acquired reading results are normalized (S103). . In the following, for the sake of simplicity, a black correction value acquisition method will be described as an example. Further, for the sake of explanation, the reading results (the amount of reflected light) of 256 patches p (0) to p (255) constituting the black test pattern K (S) created with only small dots are expressed as “AD (0 ) To AD (255) ". Then, the controller normalizes the read results AD (0) to AD (255) of the patches p (0) to p (255) of the input gradation values by the following equation (1). In Expression (1), “R (j)” is a normalized value, that is, a density value representing the density of the input tone value j, and “AD (j)” is the input tone value j to be processed. Of the patch p (j), “AD (0)” is the read result of the patch p (0) with the input gradation value 0, and “AD (255)” is the patch of the input gradation value 255. This is a reading result of p (255).

  The density value R (0) corresponding to the lightest input gradation value 0 is “1”, and the density value R (255) corresponding to the darkest input gradation value 255 is “0”. In this embodiment, it is assumed that the reflected light amount AD (j) output from the optical sensor 51 decreases as the patch density increases. Therefore, the smaller the density value R (j), the higher the density. As described above, the controller normalizes the reading result of the test pattern for each dot size and for each color according to the equation (1).

  FIG. 8A is a graph showing the relationship between the density value R obtained by normalizing the read result of the black test pattern K (S) composed of only small dots and the target density value T, and FIG. It is a figure explaining a tone value table and a correction dot number table. The horizontal axis of the graph of FIG. 8A represents the input gradation values 0 to 255, and the vertical axis represents the density value R (j) obtained from Expression (1). A solid line R in the graph represents density values R (0) to R (255) obtained from the equation (1) based on the read result of the test pattern K (S), and a dotted line T in the graph represents each input gradation value. Represent target density values T (0) to T (255).

  Next, the controller acquires a correction gradation value for each input gradation value 0 to 255 for each dot size from the relationship between the density value R and the target density value T (FIG. 8A). A value table (left figure in FIG. 8B, corresponding to the correspondence) ”is created (S104). As shown in the figure, in the correction gradation value table, for each input gradation value (example: 255), a small dot correction gradation value (example: Hs (255)) and a medium dot correction gradation value. (Example: Hm (255)) and the correction gradation value of a large dot (Example: Hl (255)) are associated with each other.

  In order to create the corrected gradation value table, the controller first sets an actual density value (example: R (127)) in the input gradation value (example: 127) to be processed as a target from the graph of FIG. 8A. It is checked whether or not it matches the density value (for example, T (127)), and if it matches, the input tone value becomes the corrected tone value. On the other hand, if the actual density value does not match the target density value, the controller displays the actual density value (eg, R (122)) that matches the target density value (eg, T (127)). The input gradation value (example: 122) corresponding to the actual density value (example: R (122)) read from the graph of 8A is corrected gradation value of the input gradation value (example: 127) to be processed. To decide.

  By doing so, for example, even in the printer 1 that prints a test pattern of small dots at a density (eg, R (127)) that is darker than the target density value (eg, T (127)), the lightness is corrected lightly. By printing a small dot test pattern with a corrected gradation value (eg, 122), a test pattern with a target density value (eg, T (127)) can be printed.

  Next, the controller, based on the correction gradation value table (the left diagram in FIG. 8B), for each dot size, the correction dot number (correction dot generation rate) relative to the dot generation number (dot generation rate) in the dot generation rate table. And a “correction dot number table (the right diagram in FIG. 8B, corresponding to the first correspondence)” is created (S105). That is, the relationship between the input gradation values 0 to 255 and the correction gradation value is replaced with the relationship between the number of dot generations (0 to 4080) and the number of correction dots. As shown in the figure, in the correction dot number table, for each dot generation number (example: 4080), the correction dot number for small dots (example: ss (4080)) and the correction dot number for medium dots (example: ms). (4080) and the correction dot number of large dots (example: ls (4080)) are associated with each other.

  In order to create the correction dot number table, the controller determines the relationship between the input gradation value and the dot generation rate (dot generation number) shown in FIG. 7C, and the input gradation value and the correction gradation in the correction gradation value table. The correction dot number of the dot generation number corresponding to each input gradation value 0 to 255 is acquired from the ratio with the value. Note that the correction dot number of the dot generation number that does not correspond to the input gradation values 0 to 255 is obtained by linear interpolation.

  FIG. 9 is a diagram for explaining how the correction value for the input gradation value is acquired based on the first paper S1 and the black dot generation rate table. Next, the controller corrects the dot generation rate table of each sheet S based on the correction dot number table (the right diagram in FIG. 8B), and also corrects the large dot conversion value (S106). Here, the first paper S1 and the black dot generation rate table will be described as an example. In the dot generation rate table shown in FIG. 9, the number of dot generations of each size generated in the unit area (4080 pixels) on the paper S is associated with each input gradation value.

  In the dot generation rate table, “large dot conversion values L (0) to L (255)” are associated with the input gradation values 0 to 255 (corresponding to the second correspondence relationship). The large dot conversion value L is a number obtained by replacing dots of three types of sizes generated in the unit area (4080 pixels) on the paper S with a large dot at a certain input gradation value. This is the number of large dots that can be formed by the amount of ink ejected to the area. The large dot conversion value L can be calculated by the following equation (2). In Equation (2), “ss” is the number of dots generated for small dots, “ms” is the number of dots generated for medium dots, “ls” is the number of dots generated for large dots, and “IS” is the ink forming the small dots. “IM” represents the amount of ink that forms a medium dot, and “IL” represents the amount of ink that forms a large dot.

  For example, assume that the ink amount IS for forming small dots is 4 pl, the ink amount IM for forming medium dots is 9 pl, and the ink amount IL for forming large dots is 15.5 pl. It is assumed that the dot generation number ss and ms of dots is 1632 and the dot generation number ls of large dots is 209. In this case, the large dot conversion value L (160) in the input gradation value 160 is 1577.8 (= 1632 × (4 / 15.5) + 1632 × (9 / 15.5) +209). The memory 13 does not always store the large dot conversion value L together with the dot generation rate, but the controller may calculate the large dot conversion value L during the density calibration process.

  Then, the controller calculates the dot generation number (dot generation rate) in the first paper S1 and black dot generation rate table (upper diagram in FIG. 9) based on the correction dot number table (right diagram in FIG. 8B). Correction is performed, and a corrected dot generation rate table (lower diagram in FIG. 9) is created. For example, when the dot generation number ss1 (160) of small dots in the input gradation value 160 is 1632, the controller refers to the correction dot number table and the correction dot number 1487 of small dots corresponding to the dot generation number 1632 is obtained. Get pieces. Then, as shown in the lower diagram of FIG. 9, the correction dot generation rate ss1 '(160) of small dots corresponding to the input tone value 160 is set to 1487 in the correction dot generation rate table.

  In this way, the controller corrects the number of dot generations (dot generation rate) of each size corresponding to each input gradation value, and creates a corrected dot generation rate table. When the print data indicates a certain input gradation value j, the printer 1 causes the printer 1 to print an image with the correction dot generation number (correction dot generation rate) corresponding to the input gradation value j, so that the printer 1 The density of the image to be printed can be brought close to the target density.

  Thereafter, the controller calculates the correction values L ′ (0) to L ′ of the large dot conversion value according to the equation (2) based on the number of correction dot generations of each size corresponding to each input gradation value (the lower diagram in FIG. 9). (255) is calculated. For example, it is assumed that the correction dot generation number of small dots in the input tone value 160 is 1487, the correction dot generation number of medium dots is 1451, and the correction dot generation number of large dots is 203. In this case, the correction value L ′ (160) of the large dot conversion value for the input gradation value 160 is 1429.3 (= 1487 × (4 / 15.5) + 1451 × (9 / 15.5) +203). . When the print data indicates the input gradation value 160, the printer 1 has a dot generation rate such that the large dots corresponding to the correction value L ′ (160) of the large dot conversion value are formed in the unit area. By printing the image, the density of the image printed by the printer 1 can be brought close to the target density.

  Therefore, the controller reads the large dot conversion value L closest to the correction value L ′ of the large dot conversion value from the dot generation rate table (upper diagram in FIG. 9), and inputs corresponding to the read large dot conversion value L. The gradation value is determined as a correction value (S107). For example, the correction value L ′ (160) (= 1429.3) of the large dot conversion value in the input gradation value 160 is the largest of the large dot conversion value L (151) (= 1426.8) in the input gradation value 151. close. In this case, the correction value of the input gradation value 160 is determined to be 151. Then, when the print data indicates the input gradation value 160, the printer 1 prints an image with the correction value 151, so that the number of large dots corresponding to the correction value L ′ (160) of the large dot conversion value becomes the unit area. The image can be printed on the printer 1 with the dot generation rate that is formed as described above, and the density of the image printed by the printer 1 can be brought close to the target density.

  As described above, the controller performs each input based on the large dot conversion value correction values L ′ (0) to L ′ (160) corresponding to the input gradation values 0 to 255 and the dot generation rate table. A correction value corresponding to the gradation value 0 to 255 is determined. Then, as shown in FIG. 3B, a correction value table corresponding to the first sheet S1 and black is created. For other sheets S, the controller is based on a dot generation rate table corresponding to each sheet S (upper figure in FIG. 9) and a correction dot number table common to all sheets S (right figure in FIG. 8B). To create a correction value table. The controller also creates correction value tables for other colors.

  Finally, the controller on the computer side transmits the created correction value table (FIG. 3B) to the printer 1. The controller 10 on the printer 1 side that has received the correction value table stores the correction value table in the memory 13 (S108). Thus, the density calibration process is completed.

  As described above, the density calibration process according to the present embodiment is summarized. First, the printer 1 applies the test patterns K (S) to Y (L) common to the respective sheets S to the first sheet S1 (the first sheet S1) (first sheet S1). Print on the medium. Then, the controller on the computer side, based on the test pattern reading result, correlates the input gradation values 0 to 255 with the correction gradation values for each dot size (see FIG. 8B). (The figure on the left corresponds to the correspondence). Then, the controller acquires a correction value of the input gradation value for printing an image on the first sheet S1, based on the correction gradation value table and the dot generation rate table of the first sheet S1, and Based on the correction gradation value table and the dot generation rate table of another sheet (second medium), the correction value of the input gradation value for printing an image on another sheet is also acquired.

  That is, the printer 1 according to the present embodiment prints print data based on the dot generation rate table used for printing on the first sheet S1 and the input tone value corrected based on the test pattern reading result. Printing is performed based on the dot generation rate table used for printing on the second sheet S2 different from the first sheet S1 and the input tone value corrected based on the test pattern reading result. Data is printed on the second sheet S2. Specifically, the printer 1 acquires a correction gradation value corresponding to the input gradation value based on the correction gradation value table, and the dot generation rate specified from the correction gradation value based on the dot generation rate table. Is acquired for each dot size, and printing is performed based on the dot generation rate for each dot size.

  Therefore, in this embodiment, the test pattern is not printed for each type of paper S as in the comparative example, that is, the test pattern is not printed by the print data created in the dot generation rate table of each paper S. In addition, the correction value of the input gradation value corresponding to the dot generation rate table of each sheet S can be obtained. Therefore, it is not necessary to print a test pattern for each type of paper S, and the number of times the test pattern is printed or read can be reduced, so that the density calibration process can be simplified. Further, it is possible to reduce the consumption of ink and paper S for printing the test pattern.

  Further, in this embodiment, the controller on the computer side calculates the dot generation number (dot generation rate) and the correction dot in the dot generation rate table for each dot size based on the correction gradation value table (left diagram in FIG. 8B). A correction dot number table (corresponding to the first correspondence relationship on the right side of FIG. 8B) is acquired in which the number (correction dot generation rate) is associated. Further, the controller calculates the input tone value and the large dot conversion value L (the dot generation rate of each size at each input tone value based on the dot generation rate table (upper diagram in FIG. 9) of each paper S. And a relationship (corresponding to a second correspondence relationship) associated with the dot generation rate of large dots). Then, based on the dot generation rate table and the correction dot number table for each sheet S, the controller calculates the dot generation number (dot generation rate) of each size at a certain input gradation value j as the correction dot generation number (correction dot generation). After that, the correction value L ′ of the large dot conversion value (the value obtained by converting the correction dot generation rate of each size into the dot generation rate of the large dot) is acquired, and the correction value L ′ of the large dot conversion value is obtained. The closest large dot conversion value L is selected from the dot generation rate table (second correspondence), and the input gradation value corresponding to the selected large dot conversion value L is used as the correction value for the input gradation value j. .

  By doing so, the correction value of the input gradation value corresponding to the dot generation rate table of each sheet S is obtained from the correction gradation value for each dot size for each input gradation value (that is, from the correction gradation value table). Can be sought.

=== Density Calibration Processing: Example 2 ===
FIG. 10 is a diagram for explaining density calibration processing according to the second embodiment. In the second embodiment, similarly to the first embodiment, a test pattern common to each sheet S is printed for each dot size, and the input gradation value and the correction level are changed for each dot size based on the read result of the test pattern. A “corrected gradation value table (left figure in FIG. 10)” in which tone values are associated is acquired. Thereafter, in the second embodiment, the controller on the computer side inputs the correction gradation value of each dot size at a certain input gradation value j based on the correction gradation value table and the dot generation rate table of each paper S. A weighted average value is obtained by the ratio of the total number of dot generations (total dot generation rate) and the number of dot generations of each size (dot generation rate) in the gradation value j, and the weighted average value is obtained as the input gradation value j. The correction value.

Specifically, the controller calculates a correction value G for each input gradation value by the following equation (3). In Equation (3), “ss” is the number of small dots generated, “ms” is the number of medium dots, “ls” is the number of large dots, and “Hs” is the small dot correction gradation. The value “Hm” represents the correction gradation value of the medium dot, and “Hl” represents the correction gradation value of the large dot.

  For example, in the correction gradation value table, the correction gradation value for small dots in the input gradation value 100 is 107, the correction gradation value for medium dots is 108, and the correction gradation value for large dots is 109. Suppose. In the dot generation rate table of the first sheet S1, the dot generation number of small dots in the input gradation value 100 is 55, the dot generation number of medium dots is 120, and the dot generation number of large dots is 549. Suppose there was. In this case, the controller determines the correction value G of the input gradation value 100 to 109 (= (55 × 107 + 120 × 108 + 549 × 109) / (55 + 120 + 549) = 108.68...).

  Also in this case, the correction value G of the input gradation value corresponding to the dot generation rate table of each sheet S from the correction gradation value for each dot size for each input gradation value (ie, from the correction gradation value table). Can be requested.

The method of obtaining the correction value G for each input tone value is not limited to the above method. For example, as shown in the following equation (4), in addition to the number of dot generations (dot generation rate) for each size, the amount of ink for forming dots of each size may be considered, and a weighted average may be used. In Expression (4), “IS” represents an ink amount for forming a small dot, “IM” represents an ink amount for forming a medium dot, and “IL” represents an ink amount for forming a large dot.

  For example, assume that the ink amount for forming small dots is 4 pl, the ink amount for forming medium dots is 9 pl, and the ink amount for forming large dots is 15.5 pl. In this case, the controller sets the correction value G of the input gradation value 100 to 109 (= (55 × 4 × 107 + 120 × 9 × 108 + 549 × 15.5 × 109) / (55 × 4 + 120 × 9 + 549 × 15.5) = 108. .84).

  A value obtained by simply averaging the correction gradation values for each input gradation value for each dot size may be used as the correction value G for each input gradation value. In this case, for example, the correction value G of the input gradation value 100 is determined as 108 (= (107 + 108 + 109) / 3).

=== Density Calibration Processing: Example 3 ===
11A and 11B are diagrams illustrating density calibration processing according to the third embodiment. Even when creating print data for printing an image on the same sheet S1, different dot generation rate tables may be used depending on the print mode set in the printer 1. For example, when a photo mode for printing an image such as a photo (corresponding to the first mode) is set, a dot generation rate in which dots of three types of sizes are generated and small dots are not generated at a high input gradation value Assume that a table (corresponding to the first table) is used. On the other hand, when a design drawing mode for printing a design drawing (corresponding to the second mode) is set, a large dot is not generated, and instead a dot generation rate at which a small dot is generated even with a high input gradation value Assume that a table (corresponding to the second table) is used.

  In this case, in order to obtain correction values corresponding to the dot generation rate table for the photo mode, it is necessary to print test patterns of three types of dot sizes. There is no need to print up to patches. On the other hand, in order to obtain the correction value corresponding to the dot generation rate table for the design drawing mode, it is only necessary to print the test pattern of small dots and medium dots, but even with the test pattern of small dots, a high input tone value It is necessary to print up to the patch. Nevertheless, if the test pattern configuration is shared regardless of the print mode, a patch with a high input tone value is printed unnecessarily, or a large dot test pattern is printed unnecessarily. End up. As a result, paper and ink for printing the test pattern are wasted.

  Therefore, in the third embodiment, when the density calibration process is performed in the manufacturing process of the printer 1 or the user, the controller on the computer side (or the printer 1 side) sets the photo mode in the printer 1 to be processed. It is determined whether or not the design drawing mode is set. Then, the configuration of the test pattern is varied according to the set mode. Specifically, the upper limit value and interval (step) of the input gradation value for printing the test pattern are varied. In the above-described first embodiment (FIG. 7), a test pattern composed of patches p (0) to p (255) of all input gradation values is taken as an example, but in the third embodiment, every predetermined number. An example is a test pattern composed of patches of input tone values.

  For example, when the photo mode is set (FIG. 11A), the controller prints test patterns of three types of dot sizes. In the medium dot and large dot test patterns (for example, K (M), K (L)), the input gradation value interval is set to 16, and the input gradation value upper limit value is set to 255. Specifically, a patch p (0) with an input gradation value 0, a patch p (16) with an input gradation value 16, a patch p (32) with an input gradation value 32, and the like are arranged in order, and the input gradation value 255. Up to patch p (255). On the other hand, in the small dot test pattern (for example, K (S)), it is not necessary to print a patch with a high input gradation value, so the input gradation value interval is set to 12, and the upper limit value of the input gradation value is set. 192. Specifically, a patch p (0) with an input tone value of 0, a patch p (12) with an input tone value of 12, a patch p (24) with an input tone value of 24, etc. are arranged in order, and the input tone value 192 Up to patch p (192).

  On the other hand, when the design drawing mode is set (FIG. 11B), the controller prints only the test pattern of small dots and medium dots. Therefore, if the test pattern is printed on the paper S1 having the same size as in the photo mode, the length of each test pattern in the moving direction can be increased. Further, in the design drawing mode, even a small dot test pattern needs to be printed up to a patch with a high input gradation value. Therefore, in each test pattern of small dots and medium dots, the interval between the input gradation values is set to 9, and the upper limit value of the input gradation values is set to 255. Specifically, a patch p (0) with an input tone value of 0, a patch p (9) with an input tone value of 9, a patch p (18) with an input tone value of 18, etc. are arranged in order, and the input tone value of 255 Up to patch p (255).

  In this way, at least one of the upper limit value of the input gradation values for each dot size for printing the test pattern and the interval of the input gradation values for each dot size are made different. Thus, by changing the configuration of the test pattern according to the print mode, an unnecessary dot size test pattern and an unnecessary input tone value patch are not printed. Therefore, wasteful consumption of paper and ink can be suppressed. Further, instead of printing unnecessary test patterns and patches, the interval between input gradation values can be reduced. That is, since it is possible to obtain the reading results for more input gradation values, it is possible to obtain a more accurate correction value.

  Therefore, when the printer 1 is manufactured, for example, when the first printer that uses the dot generation rate table for the photo mode for printing on the first sheet S1 is manufactured, a test pattern for each dot size is generated by the first printer. The dot generation rate table for each medium used in the first printer is corrected based on the result of reading the test pattern printed on one sheet S1 and printed by the first printer. On the other hand, when manufacturing a second printer that uses the design drawing mode dot generation rate table for printing on the first sheet S1, a test pattern for each dot size is printed on the first sheet S1 by the second printer. Based on the reading result of the test pattern printed by the second printer, the dot generation rate table for each medium used in the second printer 1 is corrected. At this time, the test pattern to be printed by the first printer and the test pattern to be printed by the second printer differ in at least one of the upper limit value and the interval of the input gradation values for each dot size.

=== Modification ===
<Modification 1>
In the above embodiment, the optical sensor 51 provided on the carriage 31 irradiates the test pattern with light and detects the density of the test pattern based on the amount of reflected light. However, the present invention is not limited to this. For example, the printer 1 and the optical sensor may be separated. Further, for example, the color value of the test pattern may be acquired by a colorimeter, and the correction value of the input tone value may be obtained based on the difference between the acquired color value and the target color value.

<Modification 2>
In the above embodiment, a test pattern in a gradation format in which input tone values continuously change is printed (that is, it is composed of patches p (0) to p (255) of all input tone values. Test pattern is printed), but not limited to this. For example, it may be a test pattern composed of patches of a part of input gradation values among the input gradation values 0 to 255. Each patch may be separated in the movement direction.

<Modification 3>
In the above embodiment, the controller 10 on the printer 1 side and the controller on the computer side correspond to the control unit, and the printing system in which the printer 1 and the computer are connected corresponds to the printing apparatus. However, the present invention is not limited to this, and the processing on the computer side may be performed by the controller 10 on the printer 1 side. In this case, the printer 1 alone corresponds to the printing apparatus.

<Modification 4>
In the above embodiment, the printer 1 in which the operation of ejecting ink while the head 41 moves in the moving direction and the operation of transporting the paper S in the transport direction is taken as an example, but the present invention is not limited thereto. . For example, a printer that ejects ink from the head toward the sheet S when the sheet S passes under a fixed head in which nozzles are arranged in the width direction of the sheet S in a direction crossing the width direction may be used. In such a printer, when the optical sensor 51 is also provided at a position facing the paper like the head, the input tone value of the test pattern may be changed along the transport direction. Further, for example, on the paper S conveyed to the printing area, an image is printed by repeating an operation of printing an image while moving the head in the X direction and an operation of moving the head in the Y direction. A printer that conveys a portion of the paper S on which an image has not yet been printed to the printing area may be used.

<Modification 5>
In the above embodiment (Example 3), at least one of the upper limit value of the input gradation value for each dot size for printing the test pattern and the interval of the input gradation value for each dot size is the same. Different printers may be used, but different printers may be used. Specifically, between printers that use different dot generation rate tables for the same paper S (for example, between a first printing device that uses the first table and a second printing device that uses the second table). These configurations of the test pattern may be different. Even in this case, in each printer, an image is printed on the first sheet S1 based on the correction gradation value table acquired by the test pattern printed on the first sheet S1 and the dot generation rate table of the first sheet S1. The correction value of the input gradation value for printing the image is acquired, and the image on the other sheet is obtained based on the correction gradation value table and the dot generation rate table of the other sheet (corresponding to the second medium). The correction value of the input gradation value for printing is also acquired.

<Modification 6>
In the above embodiment, the computer connected to the printer 1 performs the print data creation process shown in FIG. 3A. However, the present invention is not limited to this, and the printer 1 may perform the print data creation process. The printer 1 may perform color conversion processing, input tone value correction processing, and halftone processing, for example. Further, the printer 1 is not limited to the correction value calculation process illustrated in FIG. 6 and the like, and the computer may perform the correction value calculation process. The correction value table shown in FIG. 3B is not limited to being stored in the memory 13 in the printer 1, but may be stored in a memory on the computer side, stored in a storage medium together with the printer driver, or via the Internet. Or make it downloadable. Also, it is the printer that prints the print data based on the dot generation rate table used for printing on each medium and the input gradation value corrected based on the read result of the test pattern for each dot size. It is not limited to 1 and may be a computer.

  As mentioned above, said embodiment is for making an understanding of this invention easy, and is not for limiting and interpreting this invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

1 Printer, 10 Controller, 11 Interface section,
12 CPU, 13 memory, 14 unit control circuit,
20 transport unit, 30 carriage unit, 31 carriage,
40 head units, 41 heads,
50 detector groups, 51 optical sensors, 511 light emitting part, 512 light receiving part,
60 computers

Claims (7)

The print data is printed on the medium based on the dot generation rate table that specifies the dot generation rate for each dot size of dots formed on the medium and the input tone value associated with the dot generation rate for each dot size. A printing device for
A head that ejects ink toward a medium and forms the dots of a plurality of sizes on the medium;
A controller for performing printing by discharging ink from the head ,
The controller is
Print a test pattern for each dot size on the first medium,
Upon printing of the print data to the first medium, it corrected input Chikarakaicho value on the basis of the read result of the test pattern printed on the first medium and (G), for printing on a first medium Printing based on the first dot generation rate table to be used ;
During printing on the different second medium and the first medium is corrected input Chikarakaicho value on the basis of the read result of the test pattern printed on the first medium and (G), a second medium Printing is performed based on the second dot generation rate table used for printing
Printing device comprising a call. The printing apparatus according to claim 1,
The controller is
A corrected gradation value table that associates an input gradation value before correction with a corrected gradation value for each dot size on the first medium based on the reading result of the test pattern printed on the first medium. Store
Using the corrected gradation value table in the first medium, obtain a corrected input gradation value (G) corresponding to the input gradation value before correction ,
Based on the dot generation rate table for medium to be subjected to printing, the dot generation rate is specified from the corrected input gradation value (G) was obtained for each dot size,
Based on the obtained Dots generation rate of each of the de Ttosaizu performs printing on the medium,
A printing apparatus characterized by that. The printing apparatus according to claim 2,
The controller is
Based on the corrected gradation value table , the dot generation rate for each dot size in the first dot generation rate table is corrected to the corrected dot generation rate for each dot size, and the correction for each corrected dot size is performed. Convert the dot generation rate to a dot generation rate of a specific dot size , obtain the first correspondence relationship,
In the second dot generation rate table for the second medium, the dot generation rate for each dot size is converted into a dot generation rate of a specific dot size , and the second correspondence relationship is acquired,
The first correspondence relationship indicates correspondence between each input gradation value and a dot generation rate of a specific dot size in the first medium.
The second correspondence relationship indicates correspondence between each input gradation value and a dot generation rate of a specific dot size in the second medium.
A printing apparatus , wherein the control unit determines the corrected input tone value (G) in printing on the second medium according to the following procedures (a) to (c) ;
(A) Using the first correspondence relationship, obtain a dot generation rate of a specific dot size in the first medium corresponding to the input gradation value before correction.
(A) A dot generation rate of a specific dot size on the second medium closest to the second correspondence relationship is selected with respect to the dot generation rate of the specific dot size on the acquired first medium.
(C) For the dot generation rate of the specific dot size on the selected second medium, select the input tone value corresponding to the second correspondence as the corrected input tone value (G). To do. The printing apparatus according to claim 2,
The controller is
For each input tone value, a corrected gradation value of each dot size in the corrected gradation value table, the ratio of the dot generation rate of each size in the first dot generation rate table for said first medium A weighted average value is obtained and set as a corrected input tone value (G) .
A printing apparatus characterized by that. The printing apparatus according to any one of claims 1 to 4, wherein:
The first medium is a medium that uses a dot generation rate table with a maximum amount of ink that can be ejected per unit area as a dot generation rate table used for printing on the medium.
A printing apparatus characterized by that. The printing apparatus according to any one of claims 1 to 5, wherein
In each of the first mode in which the first dot generation rate table used for printing on the first medium is the first table and the second mode in which the second table is the second table, Printing is possible by ejecting ink from the head,
The test pattern includes an upper limit value of the input gradation value for each dot size and a dot size for each dot size depending on whether the first mode is set or the second mode is set. Ru is printed at least one with different of the interval of the input tone values,
A printing apparatus characterized by that. The print data is printed on the medium based on the dot generation rate table that specifies the dot generation rate for each dot size of dots formed on the medium and the input tone value associated with the dot generation rate for each dot size. Printing method
When discharging ink from the head toward the medium and forming the dots of a plurality of sizes on the medium for printing,
Print a test pattern for each dot size on the first medium,
Upon printing of the print data to the first medium, it corrected input Chikarakaicho value on the basis of the read result of the test pattern printed on the first medium and (G), for printing on a first medium Printing based on the first dot generation rate table to be used ;
During printing on the different second medium and the first medium is corrected input Chikarakaicho value on the basis of the read result of the test pattern printed on the first medium and (G), a second medium Printing is performed based on the second dot generation rate table used for printing
Printing wherein a call.