Printing system and correction value determination method

Abstract

To improve usability when adjusting printing characteristics on the basis of a captured image of a test pattern captured by an imaging unit separate from a printing apparatus.SOLUTION: A printing system includes a printing apparatus that prints a test pattern for determining a correction value used for adjusting printing characteristics on a medium, an imaging unit that is separate from the printing apparatus and generates a captured image of the test pattern by imaging the test pattern, and a control unit that performs a process of acquiring the captured image from the imaging unit and determining the correction value. When a provisional value of the correction value obtained from the test pattern included in the captured image is included in a predetermined allowable range, the controller determines the provisional value as the correction value, and when the provisional value is out of the allowable range, the controller determines an alternative correction value inside a boundary of the allowable range in the allowable range as the correction value.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a printing system for determining correction values ​​for adjusting print characteristics based on a captured image of a test pattern, and a correction value determination method. [Background technology]

[0002] Scanners are commonly used to read test patterns used to adjust the printing characteristics of printing devices such as inkjet printers. To improve the convenience of adjusting printing characteristics, a camera-equipped mobile device such as a smartphone can be used instead of a scanner. This means that the user must hold the camera-equipped mobile device in their hand to capture the test pattern. In this case, the angle and distance between the test pattern and the camera may be inconsistent, which could result in the test pattern in the captured image not providing a correction value within the normal range. If an abnormal correction value is obtained, the printing characteristics cannot be adjusted correctly.

[0003] For reference, the image forming apparatus disclosed in Patent Document 1 compares the current detection value of the patch toner image density with past detection values ​​to determine whether it is at or near the correction limit. If it determines that the correction limit is not reached or is not near the correction limit, it repeats a correction process to correct the exposure parameters so that the detection value approaches a predetermined reference value for each patch formation. If the number of times the correction process has been executed reaches the upper limit but it is determined that the correction limit is not reached or is not near the correction limit, the image forming apparatus displays an abnormal termination on the UI display and terminates the correction of the exposure parameters. The abnormal termination display indicates an error notification and means that the exposure parameters will not be corrected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-10269 Summary of the Invention [Problem to be solved by the invention]

[0005] When a user captures a test pattern while holding a mobile device with a camera in their hand, if a correction value within the normal range cannot be obtained and an error is notified, the user must re-capture the test pattern with the mobile device with a camera and perform the necessary steps to obtain the correction value. Since print characteristics cannot be adjusted without obtaining the correction value, the user must perform the aforementioned steps until the error no longer occurs. Therefore, it is desirable to avoid the inconvenience of inappropriate adjustment of print characteristics due to impossible correction values ​​or the inability to perform print characteristic adjustment due to an error. [Means for solving the problem]

[0006] The printing system of the present invention comprises: a printing device that prints a test pattern on a medium to determine a correction value used to adjust printing characteristics; an imaging unit that is separate from the printing device and captures an image of the test pattern to generate a captured image of the test pattern; a control unit that acquires the captured image from the imaging unit and performs processing to determine the correction value, The control unit determining the provisional value of the correction value, which is calculated from the test pattern included in the captured image, as the correction value when the provisional value is within a predetermined tolerance range; When the provisional value is outside the allowable range, an alternative correction value that is inside the boundary of the allowable range is determined as the correction value.

[0007] A correction value determination method of the present invention is a correction value determination method that determines a correction value to be used for adjusting printing characteristics using a printing device that prints a test pattern on a medium, and an imaging unit that is separate from the printing device and that generates an image of the test pattern by imaging the test pattern, the method comprising: a captured image acquisition step of acquiring the captured image from the imaging unit; a first correction value determination step of determining a provisional value of the correction value, which is obtained from the test pattern included in the captured image, as the correction value when the provisional value is within a predetermined allowable range; a second correction value determination step of determining, when the provisional value is outside the allowable range, an alternative correction value that is inside the boundary of the allowable range as the correction value; The present invention has an aspect including the following. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram schematically illustrating an example of a printing system. [Figure 2] FIG. 1 is a diagram schematically illustrating an example of the configuration of a printing system. [Figure 3] FIG. 10 is a diagram schematically illustrating an example of a medium having a test pattern. [Figure 4] FIG. 10 is a diagram schematically illustrating an example of the operation of an information terminal during imaging. [Figure 5] FIG. 10 is a diagram schematically illustrating an example of a captured image having a test pattern. [Figure 6] FIG. 10 is a diagram schematically illustrating an example of a method for determining a correction value. [Figure 7] 7A and 7B are diagrams schematically showing examples of captured images having a test pattern. [Figure 8] 10 is a flowchart illustrating an example of a correction value determination process. [Figure 9] FIG. 10 is a diagram schematically showing an example of a correction value determined from a provisional value. [Figure 10] FIG. 10 is a diagram schematically showing an example in which an alternative correction value is changed depending on a provisional correction value. DETAILED DESCRIPTION OF THE INVENTION

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes embodiments of the present invention. Of course, the following embodiments are merely examples of the present invention, and not all of the features shown in the embodiments are necessarily essential to the solution of the invention.

[0010] (1) Summary of the aspects included in the present invention: First, an overview of the embodiments included in the present invention will be described with reference to the examples shown in Figures 1 to 10. Note that the figures in this application are diagrams showing schematic examples, and the magnifications in each direction shown in these figures may differ, and the figures may not be consistent with each other. Of course, each element of this embodiment is not limited to the specific example indicated by the symbol. In the "Outline of the embodiments included in the present invention," the words in parentheses indicate supplementary explanations for the immediately preceding words.

[0011] [Aspect 1] 1 and 2 , a printing system SY1 according to one embodiment includes a printing device 2, an imaging unit 120, and a control unit U1. The printing device 2 prints a test pattern TP0 on a medium ME0 to determine a correction value V4 used to adjust printing characteristics. The imaging unit 120 is separate from the printing device 2 and captures the test pattern TP0 to generate a captured image IM0 of the test pattern TP0. The control unit U1 acquires the captured image IM0 from the imaging unit 120 and performs processing to determine the correction value V4. If a provisional value V3 of the correction value V4, calculated from the test pattern TP0 included in the captured image IM0, is within a predetermined allowable range R2, the control unit U1 determines the provisional value V3 as the correction value V4. If the provisional value V3 is outside the allowable range R2, the control unit U1 determines an alternative correction value V5, which is within the allowable range R2 and is inside a boundary R2b of the allowable range R2, as the correction value V4.

[0012] If the provisional value V3 of the correction value V4 is within the allowable range R2, the provisional value V3 is determined as the correction value V4. If the provisional value V3 is outside the allowable range R2, an alternative correction value V5 that is within the allowable range R2 and is inside the boundary R2b of the allowable range R2 is determined as the correction value V4. The alternative correction value V5 is within the allowable range R2 and is inside the boundary R2b of the allowable range R2 because the true correction value V4 is unlikely to be outside the allowable range R2 and the true correction value V4 is unlikely to be within the boundary R2b of the allowable range R2. For these reasons, problems such as inappropriate adjustment of printing characteristics based on an impossible correction value V4 or an inability to perform the adjustment of printing characteristics due to an error can be avoided. Therefore, the above-described aspect 1 can provide a printing system that can improve usability when adjusting printing characteristics based on captured images of a test pattern captured by an imaging unit separate from the printing device.

[0013] There are various examples of the above-described aspects. Examples of printing characteristics include the landing position of droplets, the transport amount of the medium, the droplet ejection state of each nozzle, and the density of the printed image. Examples of test patterns include a Bi-d adjustment pattern for performing Bi-d adjustment (bidirectional adjustment) to align the landing position of droplets on the forward and return paths, a transport amount adjustment pattern for adjusting the transport amount of the medium on which the printed image is formed, a nozzle check pattern that shows the droplet ejection status of each nozzle of the recording head, and a density pattern for adjusting the density of the printed image. Acquiring a captured image may involve storing the captured image obtained from the imaging unit in memory, or may involve controlling a DMA (Direct Memory Access) controller to store the captured image in memory, etc. Storing in memory includes storing in RAM (Random Access Memory), storing in non-volatile memory, etc. Determining a provisional value for the correction value includes requiring the provisional value to be greater than or less than a certain value because it is outside the acceptable range, or the provisional value cannot be determined because it is outside the acceptable range. Of course, the above remarks also apply to the following aspects.

[0014] [Aspect 2] As illustrated in FIG. 8, the control unit U1 may perform a print-capture process (e.g., steps S104 to S106 illustrated in FIG. 8) in which the print device 2 prints the test pattern TP0 for obtaining the provisional value V3 within a predetermined correction range R1 based on a reference value V1 for the adjustment, and the image capture unit 120 captures the test pattern TP0 to obtain the captured image IM0 from the image capture unit 120. The control unit U1 may be capable of changing the reference value V1 to a boundary value V2 of the correction range R1 and performing the print-capture process (X-1) times if the provisional value V3 obtained from the test pattern TP0 included in the captured image IM0 is outside the correction range R1, where X is an integer greater than or equal to 2. The allowable range R2 may be X times the correction range R1. If the provisional value V3 is outside a predetermined correction range R1 based on the adjustment reference value V1, the reference value V1 is changed to the boundary value V2 of the correction range R1, and the print imaging process is repeated at least once. Therefore, the above aspect can ensure a wide range in which the printing characteristics can be adjusted using the test pattern without complicating the test pattern.

[0015] [Aspect 3] 6, the correction value V4 may be a value that can be positive or negative, with 0 being the reference value at which the printing characteristics are not adjusted. The alternative correction value V5 may be a positive value smaller than the provisional value V3 when the provisional value V3 is positive, or may be a negative value larger than the provisional value V3 when the provisional value V3 is negative. Even if the provisional value V3 of the correction value V4 is an abnormal value, there is a high possibility that the adjustment direction of the printing characteristics will be the same as the sign of the provisional value V3. By having the alternative correction value V5 have the same sign as the provisional value V3, it is possible to determine an effective correction value when adjusting the printing characteristics to some extent.

[0016] [Aspect 4] 10, the alternative correction values ​​V5 may include a first alternative correction value V51 and a second alternative correction value V52 between the first alternative correction value V51 and 0. When the provisional value V3 is outside the allowable range R2, and the provisional value V3 is outside an extended range R3 that is wider than the allowable range R2, the control unit U1 may determine the first alternative correction value V51 as the correction value V4. When the provisional value V3 is outside the allowable range R2, and the provisional value V3 is included in the extended range R3, the control unit U1 may determine the second alternative correction value V52 as the correction value V4.

[0017] If the provisional value V3 falls outside the extended range R3, which is wider than the allowable range R2, the printing characteristics are likely to deviate by a relatively large amount. On the other hand, if the provisional value V3 falls outside the allowable range R2 but is included in the extended range R3, the deviation in the printing characteristics is likely to be smaller than when the provisional value V3 falls outside the extended range R3. If the provisional value V3 falls outside the allowable range R2, the correction value V4 is determined according to the degree of deviation. Therefore, the above embodiment can determine a correction value that is more effective when adjusting the printing characteristics to a certain extent. Here, the terms "first," "second," etc. in this application are terms for distinguishing between elements among a plurality of elements having similarities, and do not indicate an order. This term also applies to the following aspects.

[0018] [Aspect 5] Incidentally, a correction value determination method according to one embodiment is a correction value determination method for determining the correction value V4 using the printing device 2 and the imaging unit 120, and includes the following steps, as exemplified in FIG. (a1) A captured image obtaining step ST1 of obtaining the captured image IM0 from the imaging unit 120. (a2) A first correction value determination process ST3 for determining the provisional value V3 as the correction value V4 when the provisional value V3 of the correction value V4, which is obtained from the test pattern TP0 included in the captured image IM0, is within a predetermined tolerance range R2. (a3) A second correction value determination step ST4 for determining an alternative correction value V5 that is inside the boundary R2b of the allowable range R2 as the correction value V4 when the provisional value V3 is outside the allowable range R2. The above aspect can provide a correction value determination method that can improve usability when adjusting printing characteristics based on an image of a test pattern captured by an imaging unit separate from the printing device.

[0019] Furthermore, the above-described aspects are applicable to an information processing device including the above-described control unit, a control method for the information processing device, a control method for the above-described printing system, a correction value determination program, a control program for the above-described printing system, a computer-readable non-transitory medium on which any of the above-described programs is recorded, etc. Any of the above-described devices may be composed of multiple distributed parts.

[0020] (2) Example of a correction value determination program: Fig. 1 schematically illustrates a printing system SY1 including an information terminal 1 and a printing device 2. Fig. 2 schematically illustrates the configuration of the printing system SY1. Fig. 3 schematically illustrates a medium ME0 having a test pattern TP0. The information terminal 1 is separate from the printing device 2 and includes an imaging unit 120 and a control unit U1. Examples of the information terminal 1 include mobile phones such as smartphones, tablet devices, and digital cameras. The information terminal 1 may be composed of multiple devices separated and capable of communicating with each other, or may be a stationary device with an imaging unit connected to it so that its position can be changed. The printing device 2 is assumed to be an inkjet printer equipped with a recording head 220 capable of ejecting droplets 280. Of course, the printing device 2 may also be a thermal printer (including a thermal transfer printer) equipped with a thermal head as a recording head, an electrophotographic printer (e.g., a laser printer) equipped with a recording head that deposits toner on the medium ME0, or a 3D printer. The printing device 2 may also be composed of multiple devices separated and capable of communicating with each other. The printing device 2 is capable of forming a print image PI0 on the medium ME0, including a test pattern TP0 for determining a correction value V4 used to adjust the printing characteristics. The correction value V4 is also referred to as an adjustment value.

[0021] User US1 can adjust the printing characteristics of the printing device 2 by capturing a test pattern TP0 using an information terminal 1 equipped with an imaging unit 120 separate from the printing device 2. When user US1 captures the test pattern TP0 while holding the information terminal 1 in his or her hand, there is a possibility that camera shake may occur, the test pattern TP0 may be tilted, the test pattern TP0 may be too far from the imaging unit 120, or the imaging environment may be too dark. Therefore, the values ​​indicated for adjusting the printing characteristics by the test pattern TP0 in the captured image IM0 may not be within the normal range. If the values ​​for adjusting the printing characteristics are not within the normal range, the printing characteristics cannot be adjusted correctly. Furthermore, if an error is notified because the values ​​for adjusting the printing characteristics are not within the normal range, user US1 must re-capture the test pattern TP0 using the information terminal 1 and perform the steps to obtain the values ​​for adjusting the printing characteristics. Since the printing characteristics cannot be adjusted unless these values ​​are obtained, user US1 must perform the steps described above until the error no longer occurs. In this specific example, when the provisional value V3 of the correction value V4 is outside the allowable range R2 (see FIG. 6), an alternative correction value V5 that is inside the boundary R2b of the allowable range R2 is determined as the correction value V4, thereby avoiding the above-mentioned inconvenience. The allowable range R2 means the range that the correction value V4 can take, and it is assumed that the correction value V4 will not normally deviate from the allowable range R2.

[0022] The communication I / F (interface) 117 of the information terminal 1 is capable of communicating with the communication I / F 230 of the printing device 2. The information terminal 1 is capable of transmitting a correction value V4 of the printing characteristics and the like to the printing device 2 via the communication I / Fs 117 and 230. Upon receiving the correction value V4, the printing device 2 stores the correction value V4 and adjusts the printing characteristics based on the correction value V4. Communication via the communication I / Fs 117 and 230 may be wireless communication in accordance with standards for a wireless LAN (Local Area Network), wired communication, or even network communication such as the Internet.

[0023] 2 includes a main control unit 110, a storage unit 114, an operation unit 115, a display unit 116, a communication I / F 117, and an imaging unit 120. The information terminal 1 may also include sensors SS1 and SS2 connected to the main control unit 110. The main control unit 110 includes a CPU (Central Processing Unit) 111, which is a processor, a ROM (Read Only Memory) 112, and a RAM (Random Access Memory) 113. The RAM 113 is an example of a memory for storing a captured image IM0 obtained from the imaging unit 120. The elements of the information terminal 1 (110, 114 to 117, etc.) excluding the imaging unit 120 are examples of a control unit U1.

[0024] The storage unit 114 stores an OS (operating system), application programs, etc. The application programs include a correction value determination program PR0 for imaging a medium ME0 having a test pattern TP0. The storage unit 114 may be a nonvolatile semiconductor memory such as a flash memory. The storage unit 114 may be removably attached to the main body of the information terminal 1. The display unit 116 displays a screen corresponding to the display information based on the display information. The display unit 116 may be a liquid crystal display panel, etc. The operation unit 115 may be a touch panel attached to the surface of the display unit 116, hard keys, etc. The display unit 116 displays a screen corresponding to the display information based on the display information.

[0025] The correction value determination program PR0 causes the information terminal 1 to realize a judgment function FU1, a first correction value determination function FU2, and a second correction value determination function FU3. The CPU 111 performs various processes by appropriately reading information stored in the storage unit 114 into the RAM 113 and executing the read program. The CPU 111 performs processes corresponding to the above-mentioned functions (FU1 to FU3) by executing the correction value determination program PR0 read into the RAM 113. The information terminal 1 that executes the correction value determination program PR0 performs a judgment step ST2 corresponding to the judgment function FU1, a first correction value determination step ST3 corresponding to the first correction value determination function FU2, and a second correction value determination step ST4 corresponding to the second correction value determination function FU3. The computer-readable medium that stores the correction value determination program PR0 that causes a computer to realize the above-mentioned functions (FU1 to FU3) is not limited to the storage unit 114, and may be a recording medium external to the information terminal 1.

[0026] The imaging unit 120 includes a lens 121, an AF (autofocus) unit 122, an image sensor 123, etc., and captures a test pattern TP0 to generate a captured image IM0 of the test pattern TP0. The image sensor 123 converts an image of light incident via the lens 121 and the AF unit 122 into an electrical signal. The image sensor 123 in this specific example outputs digital data corresponding to the electrical signal of each light receiving element. The digital data is stored in the RAM 113 as a frame FR0 or a captured image IM0. The image sensor 123 may be a CMOS (Complementary Metal-Oxide Semiconductor) image sensor, a CCD (Charge Coupled Devices) image sensor, etc.

[0027] The sensor SS1 may be a speed sensor that measures the moving speed of the imaging unit 120, or an acceleration sensor that measures the acceleration of the imaging unit 120. The sensor SS2 may be a distance sensor that measures the distance from the imaging unit 120 to the medium ME0.

[0028] The printing device 2 ejects C (cyan) ink, M (magenta) ink, Y (yellow) ink, and K (black) ink as color materials from a recording head 220 as droplets 280 to form a print image PI0 corresponding to print data. The recording head 220 has multiple nozzles Nc capable of ejecting C ink droplets onto the medium ME0, multiple nozzles Nm capable of ejecting M ink droplets onto the medium ME0, multiple nozzles Ny capable of ejecting Y ink droplets onto the medium ME0, and multiple nozzles Nk capable of ejecting K ink droplets onto the medium ME0. C, M, Y, and K inks are supplied to the recording head 220 from ink cartridges Cc, Cm, Cy, and Ck, respectively. The recording head 220 ejects C, M, Y, and K droplets 280 from the nozzles Nc, Nm, Ny, and Nk, respectively, under the control of the controller 210. When the droplets 280 land on the medium ME0, ink dots are formed on the medium ME0. The printing device 2 also includes a drive unit that changes the relative positional relationship between the recording head 220 and the medium ME0 under the control of the controller 210, such as a transport unit 225 that transports the medium ME0 in a predetermined transport direction. As a result, a printed matter is obtained having a pattern of ink dots on the medium ME0 as a print image PI0. The material of the medium ME0 is not particularly limited, and may be paper, fabric, resin, metal, or the like. The shape of the medium ME0 may be a two-dimensional cut shape, a roll, or a three-dimensional shape.

[0029] The medium ME0 shown in FIG. 3 has a Bi-d adjustment pattern as the test pattern TP0. The test pattern TP0 includes a plurality of forward pass individual patterns TP1 and the same number of backward pass individual patterns TP2 as the forward pass individual patterns TP1. Each individual pattern (TP1, TP2) is a printed image in the shape of a line segment along the sub-scanning direction D2, which is perpendicular to the main scanning direction D1. For convenience, FIG. 3 shows a value V0 corresponding to each backward pass individual pattern TP2. The value V0 becomes a correction value V4 when the position of the backward pass individual pattern TP2 in the main scanning direction D1 matches the position of the corresponding forward pass individual pattern TP1. Bi-d adjustment refers to setting a correction value V4 to align the landing positions of droplets 280 on the forward pass with the landing positions of droplets 280 on the backward pass in the main scanning direction D1 when the printing device 2 repeats main scanning and sub-scanning during printing. Here, the forward pass refers to the main scanning in which the recording head 220 moves in the forward direction D11, and the backward pass refers to the main scanning in which the recording head 220 moves in the backward direction D12. The printing device 2 prints each forward pass individual pattern TP1 on the medium ME0 on the forward pass, and each backward pass individual pattern TP2 on the medium ME0 on the backward pass. Figure 3 shows that the multiple backward pass individual patterns TP2 are offset from the multiple forward pass individual patterns TP1 in the sub-scanning direction D2, which is perpendicular to the main scanning direction D1. The multiple backward pass individual patterns TP2 may be located at the same positions as the multiple forward pass individual patterns TP1 in the sub-scanning direction D2. The sub-scanning direction D2 refers to the direction in which the recording head 220 moves relative to the medium ME0, and the transport direction in which the medium ME0 moves relative to the recording head 220 is the opposite direction to the sub-scanning direction D2.

[0030] In FIG. 3, the printing interval between the return pass individual patterns TP2 is, for example, one pixel wider than the printing interval between the forward pass individual patterns TP1. The value V0 corresponding to each return pass individual pattern TP2 is an integer value that can be either positive or negative, with 0 representing no adjustment of the printing characteristics. Of the seven values ​​V0, the center "0" represents the reference value V1 at the initial stage of adjustment. Of the seven values ​​V0, "+3," which is the furthest from the reference value V1 in the forward direction D11, represents the positive boundary value V2 in the correction range at the initial stage of adjustment. Of the seven values ​​V0, "-3," which is the furthest from the reference value V1 in the return direction D12, represents the negative boundary value V2 in the correction range at the initial stage of adjustment. For example, a return pass individual pattern TP2 with a value of "+3" indicates a shift of three pixels in the forward direction D11 from the return pass individual pattern TP2 with a reference value of "0." A return pass individual pattern TP2 with a value of "-3" is shifted by three pixels in the return direction D12 from a return pass individual pattern TP2 with a reference value of "0." The test pattern TP0 shown in Figure 3 can be considered a Bi-d adjustment pattern for determining a provisional value V3 for the correction value V4 from among -4 or less, -3, -2, -1, 0, +1, +2, +3, and +4 or more. As shown in Figure 3, when the position of the return pass individual pattern TP2 with a reference value of "0" matches the position of the forward pass individual pattern TP1 in the main scanning direction D1, the provisional value V3 is "0," and as a result, the correction value V4 is also "0."

[0031] Note that the test pattern TP0 is not limited to a Bi-d adjustment pattern, and may be a PF adjustment pattern (transport distance adjustment pattern), a nozzle check pattern, a density pattern, or the like. For example, PF adjustment refers to setting a correction value V4 to properly adjust the transport distance of the medium ME0 during sub-scanning in the sub-scanning direction D2. If the transport distance of the medium ME0 during sub-scanning is too large, gaps will appear between band areas, such as light streaks, and if the transport distance of the medium ME0 during sub-scanning is too small, dots will overlap between band areas, such as dark streaks. The PF adjustment pattern can be, for example, a collection of individual patterns that indicate whether the aforementioned streaks are eliminated.

[0032] Next, an example of the operation of the information terminal 1 when capturing an image will be described with reference to Fig. 4. Normally, capturing an image is triggered by an operation on a shutter button included in the operation unit 115. Frames FR0 constituting the moving image VD0 are transferred from the image sensor 123 of the imaging unit 120 to the RAM 113 of the main control unit 110 for each frame period. At this time, the CPU 111 may store the frames FR0 in the RAM 113, or a DMA controller (not shown) may store the frames FR0 in the RAM 113. Each frame FR0 represents a still image for each frame period, but may also contain information indicating a difference from the previous frame. Due to the processing capacity of the information terminal 1, each frame FR0 has a lower resolution than the captured image IM0. The main control unit 110 controls the AF unit 122 and the like based on the group of frames FR0. The main control unit 110 may display each frame FR0 on the display unit 116.

[0033] When the user US1 presses or touches the shutter button, the operation unit 115 accepts the operation, and the operation unit 115 notifies the main control unit 110 that the shutter button has been operated. The main control unit 110 then issues an image capture instruction IS1 to the image capture unit 120, causing the image capture unit 120 to capture an image. A captured image IM0 generated by this image capture has a higher resolution than the frame FR0, and is stored in the RAM 113. Here again, the CPU 111 may perform the process of storing the captured image IM0 in the RAM 113, or a DMA controller (not shown) may perform the process of storing the captured image IM0 in the RAM 113. When the user US1 performs an operation to save the captured image IM0, the operation unit 115 accepts the operation and notifies the main control unit 110 of a save instruction IS2. The main control unit 110 then converts the captured image IM0 into a file FL0 format and saves it in the storage unit 114. Examples of file formats include the JPEG (Joint Photographic Experts Group) format and bitmap format.

[0034] In this specific example, a provisional value V3 of the correction value V4 is calculated based on a test pattern TP0 included in a captured image IM0, as illustrated in Fig. 5. Fig. 5 schematically illustrates a captured image IM0 having the test pattern TP0. As described above, when user US1 captures test pattern TP0 while holding information terminal 1 in his or her hand, the angle and distance between test pattern TP0 and imaging unit 120 may be inconsistent, potentially resulting in an incorrect determination of provisional value V3 for correction value V4. Even if main control unit 110 performs a process to identify the position of corresponding return path individual pattern TP2 that matches the position of forward path individual pattern TP1 in the main scanning direction D1 based on test pattern TP0 included in captured image IM0 as shown in FIG. 5, provisional value V3 cannot be determined correctly. FIG. 5 shows an example in which information terminal 1 erroneously determines provisional value V3 as "+4 or more," outside correction range R1, based on test pattern TP0 included in captured image IM0. In this case, provisional value V3 cannot be used as correction value V4.

[0035] First, an example of a method for determining a correction value will be described with reference to Fig. 6. The determined correction value V4 is a value that can be either positive or negative, with 0 being the reference value at which the printing characteristics are not adjusted. The first printed test pattern TP0 has a correction range R1 from boundary value V2=-3 to boundary value V2=+3, with reference value V1=0 as the base, as shown in Figure 3. Test pattern TP0 shown in Figure 3 can be said to be a test pattern for determining provisional value V3 within correction range R1, with reference to V1=0. If the determined provisional value V3 is greater than or equal to -3 and less than or equal to +3, correction value V4 is determined to be provisional value V3.

[0036] If the provisional value V3 is -4 or less, the reference value V1 is changed to boundary value V2 = -3, and a test pattern TP0 is printed to determine the provisional value V3 within the correction range R1 from boundary value V2 = -6 to boundary value V2 = 0. If the provisional value V3 determined here is -6 or more and 0 or less, the correction value V4 is determined to be the provisional value V3. If the provisional value V3 is +4 or greater, the reference value V1 is changed to boundary value V2 = +3, and a test pattern TP0 is printed to determine the provisional value V3 within the correction range R1 from boundary value V2 = 0 to boundary value V2 = +6. If the provisional value V3 determined here is greater than or equal to 0 and less than or equal to +6, the correction value V4 is determined to be provisional value V3.

[0037] 6, the upper limit X of the number of times the test pattern is printed is 2, and the allowable range R2 of the provisional value V3 is between −6 and +6. In other words, the allowable range R2 is X=2 times the correction range R1. If the calculated provisional value V3 is less than -7, the provisional value V3 falls outside the allowable range R2. In this case, the correction value V4 is determined to be an alternative correction value V5 within the allowable range R2, i.e., between -5 and +5. This is because the true correction value V4 is unlikely to be smaller than the allowable range R2, and the probability that the true correction value V4 falls within the allowable range R2b is also low. The alternative correction value V5 is preferably greater than -5 and less than -1, and may be -5 or -4, which are not included in the first correction range R1 but are included in the second correction range R1. In this case, the alternative correction value V5 is considered to be a negative value greater than the provisional value V3 when the provisional value V3 is negative. Even if the provisional value V3 is an abnormally negative value, the adjustment direction of the printing characteristics is likely to be the same negative direction as the sign of the provisional value V3. Since the alternative correction value V5 has the same sign as the provisional value V3, a correction value V4 that is effective when adjusting the printing characteristics to some extent is determined.

[0038] If the calculated provisional value V3 is +7 or greater, the provisional value V3 falls outside the allowable range R2. In this case, the correction value V4 is determined to be an alternative correction value V5 within the allowable range R2, i.e., between -5 and +5. This is because the true correction value V4 is unlikely to be greater than the allowable range R2, and the true correction value V4 is unlikely to be within the allowable range R2's boundary R2b. The alternative correction value V5 is preferably between +1 and +5, and may be +4 or +5, which are not included in the first correction range R1 but are included in the second correction range R1. In this case, the alternative correction value V5 is considered to be a positive value smaller than the provisional value V3 when the provisional value V3 is positive. Even if the provisional value V3 is an abnormally positive value, the adjustment direction of the printing characteristics is likely to be the same positive direction as the sign of the provisional value V3. Since the alternative correction value V5 has the same sign as the provisional value V3, a correction value V4 that is effective when adjusting the printing characteristics to some extent is determined.

[0039] If the upper limit number X is 3, the allowable range R2 of the provisional value V3 is between -9 and +9. In this case, the allowable range R2 is X=3 times the correction range R1. Of course, the upper limit number X may be 4 or more.

[0040] 7A and 7B schematically illustrate an example of a captured image IM0 that is acquired when the allowable range R2 is equal to or greater than -6 and equal to or less than +6, and a provisional value V3=+5 within the allowable range R2 is correctly determined. As shown in FIG. 7A, the correction range R1 of the first printed test pattern TP0 is based on a reference value V1=0 and ranges from a boundary value V2=-3 to a boundary value V2=+3. Based on the test pattern TP0 included in the captured image IM0, the main control unit 110 performs processing to identify the position of the corresponding return path individual pattern TP2 that matches the position of the forward path individual pattern TP1. Because the correction range R1 is between -3 and +3, the main control unit 110 cannot determine a provisional value V3=+5. Based on the test pattern TP0 included in the captured image IM0, the information terminal 1 determines the provisional value V3 to be +4 or greater, changes the reference value V1 to a boundary value V2=+3, and causes the printing device 2 to print the test pattern TP0 shown in FIG. 7B. The correction range R1 of the test pattern TP0 shown in FIG. 7B ranges from a boundary value V2=0 to a boundary value V2=+6. Based on the test pattern TP0 included in the captured image IM0, the information terminal 1 can determine the provisional value V3 to be +5.

[0041] On the other hand, if the provisional value V3 cannot be calculated correctly as shown in FIG. 5, the information terminal 1 may determine the provisional value V3 to be +7 or greater based on the test pattern TP0 included in the captured image IM0. In this case, the provisional value V3 cannot be used as the correction value V4 as is. However, if an error is determined, the printing characteristics cannot be adjusted. In this specific example, the information terminal 1 determines the correction value V4 to be an alternative correction value V5 within the boundary R2b of the permissible range R2, for example, +4 or +5, in order to improve usability when adjusting the printing characteristics based on the captured image IM0 of the test pattern TP0.

[0042] (3) Example of correction value determination process: 8 shows a schematic example of a correction value determination process performed by the main control unit 110. Here, steps S104 to S106 correspond to the captured image acquisition step ST1. Steps S108 to S116 correspond to the determination step ST2 and the determination function FU1. Step S118 corresponds to the first correction value determination step ST3 and the first correction value determination function FU2. Step S120 corresponds to the second correction value determination step ST4 and the second correction value determination function FU3. Hereinafter, the word "step" may be omitted, and the step symbol may be shown in parentheses.

[0043] When the correction value determination process starts, the main control unit 110 assigns 1 to a variable N that represents the number of times the print imaging process of S104 to S106 has been executed (S102). Next, the main control unit 110 causes the printing device 2 to print a test pattern TP0 for determining a provisional value V3 within a predetermined correction range R1 based on the reference value V1 for adjustment during the Nth printing (S104). In the example shown in Fig. 6, the correction range R1 for the N=1th printing is between -3 and +3 based on the reference value V1=0. After the processing of S104, the user US1 will capture an image of the test pattern TP0 while holding the information terminal 1 in his / her hand. When the main control unit 110 accepts operation of the shutter button included in the operation unit 115, it causes the imaging unit 120 to capture an image of the test pattern TP0 and acquires the captured image IM0 generated by the imaging unit 120 from the imaging unit 120 (S106).

[0044] After processing S106, the main control unit 110 determines a provisional value V3 of the correction value V4 based on the test pattern TP0 included in the captured image IM0 (S108). For example, the main control unit 110 performs processing to identify the position of the corresponding reverse pass individual pattern TP2 that matches the position of the forward pass individual pattern TP1 in the main scanning direction D1 based on the test pattern TP0 in the captured image IM0. The main control unit 110 then acquires the value V0 associated with the identified reverse pass individual pattern TP2 as the provisional value V3, or determines that the provisional value V3 is greater or smaller than the correction range R1 because the position of the reverse pass individual pattern TP2 cannot be identified. For example, if the correction range R1 is greater than or equal to -3 and less than +3, and the provisional value V3 is greater than the correction range R1, the main control unit 110 determines that the provisional value V3 is greater than or equal to +4.

[0045] After the process of S108, the main control unit 110 determines whether or not the error in the printing characteristics can be adjusted based on the provisional value V3 (S110). When the provisional value V3 is outside the correction range R1, the correction value V4 cannot be determined from the provisional value V3. Therefore, the main control unit 110 proceeds to S112 and determines whether the variable N is less than the upper limit number X. If N < X, the main control unit 110 performs a correction amount feedback process of changing the reference value V1 to the boundary value V2 of the correction range R1 (S114), adds 1 to the variable N (S116), and returns the process to S104. In S104, the main control unit 110 causes the printing apparatus 2 to print a test pattern TP0 for obtaining the provisional value V3 within the correction range R1 with the new reference value V1 as a reference. For example, when the provisional value V3 is +4 or more, the correction range R1 of the test pattern TP0 is 0 or more and +6 or less with the reference value V1 = +3 as a reference. Thereafter, the processes of S106 to S110 are performed. When the main control unit 110 determines in S110 that the error of the printing characteristics cannot be adjusted and determines in S112 that the variable N has reached the upper limit number X, the process proceeds to S120 to end the loop of S104 to S116. Therefore, when the provisional value V3 obtained from the test pattern TP0 included in the captured image IM0 is outside the correction range R1, the main control unit 110 can execute the printing and imaging processes of S104 to S106 (X - 1) times by changing the reference value V1 to the boundary value V2 of the correction range R1.

[0046] When the provisional value V3 is included in the correction range R1 in S110, the main control unit 110 proceeds to S118, determines the provisional value V3 as the correction value V4, and ends the correction value determination process. That the provisional value V3 is included in the correction range R1 means that the provisional value V3 is included in the allowable range R2. Therefore, when the provisional value V3 obtained from the test pattern TP0 included in the captured image IM0 is included in a predetermined allowable range R2, the main control unit 110 determines the provisional value V3 as the correction value V4.

[0047] If the variable N reaches the upper limit number X in S112, the main control unit 110 determines in S120 that the alternative correction value V5, which is inside the boundary R2b of the allowable range R2, is the correction value V4, and ends the correction value determination process. If N≧X, the fact that the provisional value V3 is outside the correction range R1 means that the provisional value V3 is outside the allowable range R2. Therefore, if the provisional value V3 is outside the allowable range R2, the main control unit 110 determines the alternative correction value V5 as the correction value V4.

[0048] 9 shows a schematic example of a provisional value V3 obtained when the range R1 of one correction is equal to or larger than V1-3 and equal to or smaller than V1+3, and the upper limit number of times X is 2, and a correction value V4 determined from the provisional value V3. The alternative correction value V5 is +5 when the provisional value V3 is positive, and is −5 when the provisional value V3 is negative. In case 1, where the provisional value V3 = +1 is obtained from the test pattern TP0 that was printed and imaged the first time, the provisional value V3 is included in the correction range R1, i.e., the allowable range R2, so the correction value V4 is determined to be the provisional value V3 = +1.

[0049] In case 2, where the first provisional value V3 is +4 or greater, and the correction range R1 is changed to 0 to +6, the provisional value V3 = +4 is determined from the second test pattern TP0 that is printed and imaged, and the provisional value V3 is included in the correction range R1, i.e., the allowable range R2. Therefore, the correction value V4 is determined to be +4. In case 3, where the first provisional value V3 is +4 or more and the second provisional value V3 is +7 or more after the correction range R1 is changed to 0 or more and +6 or less, the provisional value V3 is outside the allowable range R2, so the correction value V4 is determined to be the alternative correction value V5 = +5.

[0050] In case 4, where the first provisional value V3 is -4 or less, and the second provisional value V3 is -7 or less after the correction range R1 is changed to -6 or more and 0 or less, the provisional value V3 is outside the allowable range R2, so the correction value V4 is determined to be the alternative correction value V5 = -5.

[0051] As described above, if the provisional value V3 of the correction value V4 is outside the allowable range R2, an alternative correction value V5 that is within the allowable range R2 and is inside the boundary R2b of the allowable range R2 is determined as the correction value V4. This avoids the inconvenience of inappropriate adjustment of the printing characteristics based on an impossible correction value V4 or an error that makes it impossible to adjust the printing characteristics. Therefore, this specific example improves usability when adjusting the printing characteristics based on the captured image IM0 of the test pattern TP0 captured by the imaging unit 120 separate from the printing device 2.

[0052] (4) Variation: The present invention can be embodied in various modifications. For example, the basic effect of the present invention can be obtained even when the upper limit X of the number of times test pattern printing is 1 and the allowable range R2 coincides with the correction range R1 based on the reference value V1 = 0. For example, in the test pattern TP0 shown in Fig. 7A, even if the provisional value V3 of the correction value V4 is +4 or greater or -4 or less, the alternative correction value V5, which is -2 or greater and +2 or less, is determined as the correction value V4, thereby avoiding the above-mentioned inconvenience.

[0053] As shown in FIG. 10, the main control unit 110 may perform a process of changing the alternative correction value V5 in accordance with the provisional value V3 of the correction value V4. The alternative correction values ​​V5 shown in FIG. 10 include a first alternative correction value V51 and a second alternative correction value V52 between the first alternative correction value V51 and 0. In the example shown in FIG. 10, the positive alternative correction values ​​V5 include a first alternative correction value V51 = +3 and a second alternative correction value V52 = +2 between +3 and 0. The negative alternative correction values ​​V5 include a first alternative correction value V51 = -3 and a second alternative correction value V52 = -2 between -3 and 0. The first alternative correction value V51 is an alternative correction value applied to the correction value V4 when the provisional value V3 is outside the extended range R3, which is wider than the allowable range R2. The second alternative correction value V52 is an alternative correction value applied to the correction value V4 when the provisional value V3 is outside the allowable range R2 but is included in the extended range R3. Note that in FIG. 10, the allowable range R2 is between -5 and +5, and the extended range R3 is between -10 and +10.

[0054] For example, if the provisional value V3 is +11 or greater, the provisional value V3 is outside the extended range R3, and the main control unit 110 determines the first alternative correction value V51 = +3 as the correction value V4. If the provisional value V3 is -11 or less, the provisional value V3 is also outside the extended range R3, and the main control unit 110 determines the first alternative correction value V51 = -3 as the correction value V4. In either case, if the provisional value V3 is outside the allowable range R2, and if the provisional value V3 is outside the extended range R3 which is wider than the allowable range R2, the main control unit 110 determines the first alternative correction value V51 as the correction value V4.

[0055] If the provisional value V3 is greater than or equal to +6 and less than or equal to +10, the provisional value V3 is outside the allowable range R2 but is included in the extended range R3, and the main control unit 110 determines the second alternative correction value V52 = +2 as the correction value V4. If the provisional value V3 is greater than or equal to -10 and less than or equal to -6, the provisional value V3 is also outside the allowable range R2 but is included in the extended range R3, and the main control unit 110 determines the second alternative correction value V52 = -2 as the correction value V4. In either case, when the provisional value V3 is outside the allowable range R2 but is included in the extended range R3, the main control unit 110 determines the second alternative correction value V52 as the correction value V4.

[0056] If the provisional value V3 is outside the extended range R3, the printing characteristics are likely to deviate by a relatively large amount. On the other hand, if the provisional value V3 is outside the allowable range R2 but is included in the extended range R3, the deviation in the printing characteristics is likely to be smaller than when the provisional value V3 is outside the extended range R3. If the provisional value V3 is outside the allowable range R2, the correction value V4 is determined according to the degree of deviation, making it possible to determine a correction value V4 that is more effective when adjusting the printing characteristics to a certain extent. The alternative correction value V5 may be divided into three or more stages. The correspondence between the provisional value V3 and the alternative correction value V5 may be defined in an information table or by a mathematical formula.

[0057] (5) Conclusion: As described above, according to the present invention, it is possible to provide, through various aspects, a configuration that can improve usability when adjusting print characteristics based on an image of a test pattern captured by an imaging unit separate from the printing device. Of course, even in an aspect that consists only of the elements of the independent claims, the basic functions and effects described above can be obtained. Furthermore, it is possible to implement configurations in which the components disclosed in the above examples are substituted with each other or the combination is changed, or configurations in which the components disclosed in the publicly known techniques and the above examples are substituted with each other or the combination is changed, etc. The present invention also includes these configurations. [Explanation of symbols]

[0058] 1...information terminal, 2...printing device, 110...main control unit, 111...CPU, 120...imaging unit, 210...controller, 220...recording head, D1...main scanning direction, D2...sub-scanning direction, D11...forward direction, D12...return direction, IM0...captured image, ME0...medium, PR0...correction value determination program, R1...correction range, R2...tolerance range, R2b...boundary, R3...extension range, ST1...captured image acquisition process, ST2...judgment process, ST3...first correction value determination process, ST4...second correction value determination process, SY1...printing system, TP0...test pattern, TP1...forward pass individual pattern, TP2...return pass individual pattern, US1...user, U1...control unit, V1...reference value, V2...boundary value, V3...provisional value, V4...correction value, V5...alternative correction value, V51...first alternative correction value, V52...second alternative correction value.

Claims

1. a printing device that prints a test pattern on a medium to determine a correction value used to adjust printing characteristics; an imaging unit that is separate from the printing device and captures an image of the test pattern to generate a captured image of the test pattern; a control unit that acquires the captured image from the imaging unit and performs processing to determine the correction value, The control unit determining the provisional value of the correction value, which is obtained from the test pattern included in the captured image, as the correction value when the provisional value is within a predetermined tolerance range; If the provisional value is outside the allowable range, an alternative correction value that is inside the allowable range and is further inside the boundary of the allowable range is determined as the correction value. Printing system.

2. The control unit performing a print image capture process in which the printing device prints the test pattern for obtaining the provisional value within a predetermined correction range using a reference value for the adjustment as a reference, and the image capture unit captures an image of the test pattern, thereby obtaining the captured image from the image capture unit; where X is an integer of 2 or more, and when the provisional value calculated from the test pattern included in the captured image is outside the correction range, the reference value is changed to a boundary value of the correction range and the print capturing process is executed (X-1) times, The tolerance range is X times the correction range. The printing system of claim 1 .

3. The correction value is a value that can be either positive or negative, with 0 being the reference value at which the printing characteristics are not adjusted, 3. The printing system according to claim 1, wherein the alternative correction value is a positive value smaller than the provisional value when the provisional value is positive, and a negative value larger than the provisional value when the provisional value is negative.

4. the alternative correction values ​​include a first alternative correction value and a second alternative correction value between the first alternative correction value and zero; The control unit If the provisional value is outside the allowable range and if the provisional value is outside an extended range that is wider than the allowable range, determine the first alternative correction value as the correction value; When the provisional value is outside the allowable range, if the provisional value is included in the extended range, the second alternative correction value is determined to be the correction value. The printing system according to claim 3 .

5. A correction value determination method for determining a correction value used to adjust printing characteristics, using a printing device that prints a test pattern on a medium, and an imaging unit that is separate from the printing device and that generates a captured image of the test pattern by capturing an image of the test pattern, comprising: a captured image acquisition step of acquiring the captured image from the imaging unit; a first correction value determination step of determining a provisional value of the correction value, which is obtained from the test pattern included in the captured image, as the correction value when the provisional value is within a predetermined allowable range; a second correction value determination step of determining, when the provisional value is outside the allowable range, an alternative correction value that is inside the boundary of the allowable range as the correction value; A correction value determination method including:

Images