Printing apparatus and printing method

Abstract

The detection pattern is printed, and the sensor automatically corrects for errors in media transport. [Solution] A printing apparatus that performs the following steps: a first step of forming a first pattern having a first straight section on a medium; a second step of transporting a predetermined amount of the medium after forming the first pattern; a third step of forming a second pattern having a second straight section at a position where at least a part of the second straight section overlaps with the first straight section located at a first ideal position when viewed from the width direction, and where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction; a fourth step of detecting a first intersection and a second intersection while moving a sensor across the overlapping portion of the first straight section and the second straight section located at the first ideal position when viewed from the width direction in the width direction; and a fifth step of calculating the transport error of the medium in the second step based on the first intersection and the second intersection detected in the fourth step, and correcting the amount of medium transported by the transport unit.

Description

Technical Field

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

Background Art

[0002] Conventionally, various printing apparatuses have been used. Among them, there is a printing apparatus that prints on a conveyed medium. Such a printing apparatus may cause conveyance errors depending on the medium used, such as differences in thickness, differences in elongation when tension is applied, and differences in swelling degree when ink or the like is applied. Therefore, a printing apparatus capable of detecting conveyance errors has been disclosed. For example, in Patent Document 1, a first pattern composed of two non-parallel straight lines is formed on a medium, and after the medium is conveyed by a predetermined amount in the conveyance direction, a second pattern composed of the same two straight lines as the first pattern is formed at a position where it does not overlap the first pattern, and the first pattern and the second pattern are simultaneously read by a line scanner. Then, the intersection points of the two straight lines of the first pattern and the intersection points of the two straight lines of the second pattern are calculated respectively, and a conveyance error is detected by comparing the distance in the conveyance direction between the two intersection points and the conveyance amount of the predetermined amount of the medium. An inkjet recording apparatus is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in conventional printing devices capable of detecting transport errors, such as the inkjet recording device described in Patent Document 1, detecting and correcting transport errors can be time-consuming. Furthermore, such printing devices tend to incorporate large sensors and high-precision encoders, leading to increased drive load and higher device costs. For example, the inkjet recording device described in Patent Document 1 uses a line scanner to read the first and second patterns, and the large size of the line scanner may lead to increased drive load and higher device costs. [Means for solving the problem]

[0005] The present invention, for solving the above problems, comprises a transport unit for transporting a medium in a transport direction, a printing unit for dispensing liquid onto the medium transported by the transport unit, a sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by dispensing the liquid onto the medium, and a control unit. The control unit performs a first step of controlling the printing unit to form a first pattern on the medium, which has a first straight section that constitutes the detection pattern and intersects both the transport direction and the width direction, a first step of controlling the transport unit to transport a predetermined amount of the medium after the first pattern has been formed, and defining the position where the first straight section is located when the medium has been transported by the predetermined amount without transport errors in the second step as a first ideal position, after transporting the medium by the predetermined amount, a first straight section that constitutes the detection pattern and is parallel to the first straight section. A third step is to control the printing unit to form a second pattern having a second straight section on the medium at a position where at least a part of the second straight section overlaps with the first straight section located at the first ideal position when viewed from the width direction, and where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction; a fourth step is to move the sensor so as to cross the overlapping portion where the first straight section located at the first ideal position and the second straight section overlap in the width direction, and detect a first intersection point where the first straight section and the sensor intersect, and a second intersection point where the second straight section and the sensor intersect; and a fifth step is to calculate the transport error of the medium in the second step based on the first and second intersection points detected in the fourth step, and correct the amount of the medium transported by the transport unit.

[0006] Furthermore, the present invention provides a printing method for a printing apparatus that solves the above problems, comprising: a transport unit for transporting a medium in a transport direction; a printing unit for discharging liquid onto the medium transported by the transport unit; and a sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging the liquid onto the medium, the printing method comprising: a first step of forming a first pattern on the medium by the printing unit, having a first straight section which constitutes the detection pattern and intersects both the transport direction and the width direction; a second step of transporting the medium by the transport unit by a predetermined amount after forming the first pattern; and defining the position where the first straight section is located when the medium has been transported by the predetermined amount without transport errors in the second step as a first ideal position, after transporting the medium by the predetermined amount, a first straight section which constitutes the detection pattern and is parallel to the first straight section The invention is characterized by the following steps: a third step of forming a second pattern having a second straight line portion, which is a line portion, on the medium by the printing unit at a position where at least a part of the second straight line portion overlaps with the first straight line portion located at the first ideal position when viewed from the width direction, and at a position where there is a gap between the first straight line portion located at the first ideal position and the second straight line portion in the width direction; a fourth step of moving the sensor so as to cross the overlapping portion where the first straight line portion located at the first ideal position and the second straight line portion overlap in the width direction, and detecting a first intersection point where the first straight line portion and the sensor intersect, and a second intersection point where the second straight line portion and the sensor intersect; and a fifth step of calculating the transport error of the medium in the second step based on the first and second intersection points detected in the fourth step, and correcting the amount of the medium transported by the transport unit. [Brief explanation of the drawing]

[0007] [Figure 1] A perspective view of a printing apparatus according to Embodiment 1 of the present invention. [Figure 2] Figure 1 is a perspective view showing the inside of the printing apparatus. [Figure 3]Figure 1 is a perspective view showing the inside of the printing apparatus with the carriage cover removed. [Figure 4] Figure 1 is a perspective view showing the internal structure of the printing apparatus carriage. [Figure 5] This figure shows an example of the printing state of the first frame on a medium printed with the printing apparatus shown in Figure 1. [Figure 6] A flowchart illustrating an example of a printing method performed using the printing apparatus shown in Figure 1, for forming the first and second patterns shown in Figure 5. [Figure 7] A schematic diagram showing the printing status in the flowchart of Figure 6. [Figure 8] A schematic diagram showing the positional relationship of the first and second patterns, respectively, when no transport error occurs and when a transport error occurs. [Figure 9] A schematic diagram showing the positional relationship of the first and second patterns, which have different shapes from the first and second patterns shown in Figures 5 and 8, in the case where no transport error occurs. [Figure 10] A flowchart illustrating a printing method using the printing apparatus shown in Figure 1, as an example of a printing method for forming the first and second patterns shown in Figure 9. [Modes for carrying out the invention]

[0008] First, the present invention will be described in general terms. A printing apparatus according to a first aspect of the present invention for solving the above problems comprises: a transport unit for transporting a medium in a transport direction; a printing unit for discharging liquid onto the medium transported by the transport unit; a sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging the liquid onto the medium; and a control unit. The control unit performs a first step of controlling the printing unit to form a first pattern on the medium, which has a first straight section that constitutes the detection pattern and intersects both the transport direction and the width direction; a second step of controlling the transport unit to transport a predetermined amount of the medium after forming the first pattern; and, when the position where the first straight section is located when the medium has been transported by the predetermined amount without transport errors in the second step is defined as a first ideal position, after transporting the medium by the predetermined amount, a first straight section that constitutes the detection pattern and is parallel to the first straight section A third step is to control the printing unit to form a second pattern having a second straight section, which is a straight section of the medium, at a position where at least a part of the second straight section overlaps with the first straight section located at the first ideal position when viewed from the width direction, and where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction; a fourth step is to move the sensor so as to cross the overlapping portion where the first straight section located at the first ideal position and the second straight section overlap in the width direction, and detect a first intersection point where the first straight section and the sensor intersect, and a second intersection point where the second straight section and the sensor intersect; and a fifth step is to calculate the transport error of the medium in the second step based on the first and second intersection points detected in the fourth step, and correct the amount of the medium transported by the transport unit.

[0009] According to this embodiment, the system is equipped with a sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging liquid onto the medium. By detecting the detection pattern before and after transporting a predetermined amount of medium, the transport error is calculated, and the amount of medium transported by the transport unit is corrected. In this way, by using a small sensor that is movable in a width direction perpendicular to the transport direction to detect the detection pattern and calculate the transport error, the risk of increased drive load and increased equipment costs can be reduced. Furthermore, the detection pattern can be printed and the sensor can automatically correct the transport error of the medium, reducing the risk of time and effort required for detecting and correcting transport errors.

[0010] A printing apparatus according to a second aspect of the present invention is an aspect dependent on the first aspect, characterized in that, in the printing apparatus described in claim 1, in the fifth step, the transport error is calculated as (BC)tanθ, where B is the distance in the width direction between the position of the first intersection and the position of the second intersection, C is the theoretical reference distance in the width direction between the first straight section and the second straight section, and θ is the angle obtained by subtracting the inclination of the first straight section with respect to the transport direction from 90 degrees.

[0011] According to this embodiment, the transport error is calculated as (BC)tanθ. By calculating the transport error in this way, the transport error can be calculated accurately and easily.

[0012] A printing apparatus according to a third aspect of the present invention is an aspect dependent on the second aspect, wherein the first pattern has a third straight section which is a straight section parallel to the transport direction, and the second pattern has a fourth straight section which is a straight section parallel to the transport direction, and in the third step, the fourth straight section is formed such that at least a part of the fourth straight section overlaps with the third straight section which is located at the first ideal position when viewed from the width direction, and there is a gap between the third straight section which is located at the first ideal position in the width direction and the fourth straight section. The control unit performs a sixth step between the third step and the fifth step, in which it moves the sensor across the overlapping portion in the width direction where the third straight section and the fourth straight section, which are located at the first ideal position when viewed from the width direction, overlap, and detects a third intersection point, which is the position where the third straight section and the sensor intersect, and a fourth intersection point, which is the position where the fourth straight section and the sensor intersect, and in the fifth step, instead of the reference distance, it uses the distance in the width direction between the third intersection point and the fourth intersection point.

[0013] According to this embodiment, the detection pattern has a third linear section and a fourth linear section, and the amount of media transported by the transport section is corrected in the fifth step using the third linear section and the fourth linear section. By correcting the amount of media transported in this way, the amount of media transported can be accurately corrected based on the measured value.

[0014] A printing apparatus according to a fourth aspect of the present invention is an aspect dependent on any one of the first to third aspects, characterized in that the length of the detection area of ​​the sensor in the transport direction is shorter than the length of the overlapping portion in the transport direction.

[0015] According to this embodiment, the length of the detection area of ​​the sensor in the transport direction is configured to be shorter than the length of the overlapping portion in the transport direction. This configuration makes it possible to particularly miniaturize the sensor and particularly effectively suppress increases in drive load and equipment costs.

[0016] The printing apparatus according to the fifth aspect of the present invention is an aspect dependent on any one of the first to fourth aspects, and includes a storage unit that stores in association a type of medium that can be selected as the medium and the conveyance error corresponding to each type of the medium. When starting printing, if the conveyance error corresponding to the type of the medium to be used is not stored in the storage unit, the control unit performs the first to fifth steps to calculate the conveyance error corresponding to the type of the medium to be used.

[0017] According to this aspect, if there is data in the storage unit in which the type of the medium and the conveyance error corresponding thereto are associated, the conveyance error can be calculated based on that data. By adopting such a configuration, the correction process of the conveyance error can be simplified.

[0018] The printing apparatus according to the sixth aspect of the present invention is an aspect dependent on the fifth aspect, and after calculating the conveyance error corresponding to the type of the medium to be used, the control unit associates the type of the medium to be used and the calculated conveyance error and stores them in the storage unit.

[0019] According to this aspect, after calculating the conveyance error corresponding to the type of the medium to be used, the type of the medium to be used and the calculated conveyance error are associated and stored in the storage unit. By adopting such a configuration, the correction process of the conveyance error can be simplified and the types of media can be increased.

[0020] The printing apparatus according to the seventh aspect of the present invention is an aspect dependent on any one of the first to fourth aspects, and the control unit performs the first to fifth steps to calculate the conveyance error each time a print job is executed.

[0021] According to this aspect, each time a print job is executed, the first to fifth steps are performed to calculate the conveyance error. By adopting such a configuration, each time a print job is executed, the conveyance error is corrected, so that the conveyance error can be accurately corrected without being affected by the usage environment of the printing apparatus or the like.

[0022] A printing apparatus according to the eighth aspect of the present invention is an aspect dependent on any one of the first to seventh aspects, characterized in that, in the first step, a first pattern is formed on the medium by printing image data obtained by combining image data to be printed in a print job and image data of a first pattern onto the medium, and in the third step, a second pattern is formed on the medium by printing image data obtained by combining image data to be printed in the print job and image data of a second pattern onto the medium.

[0023] According to this embodiment, the image data to be printed in the print job is combined with the image data of the first pattern and the second pattern. With this configuration, transport errors can be corrected by taking into account the degree of swelling and shrinkage of the medium due to the amount of liquid adhering to it when the image is printed in the print job.

[0024] A printing method according to a ninth aspect of the present invention is a printing method for a printing apparatus comprising: a transport unit for transporting a medium in a transport direction; a printing unit for discharging liquid onto the medium transported by the transport unit; and a sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging the liquid onto the medium, the printing method comprising: a first step of forming a first pattern on the medium by the printing unit, the first pattern having a first straight section which constitutes the detection pattern and intersects both the transport direction and the width direction; a second step of transporting the medium by the transport unit by a predetermined amount after forming the first pattern; and defining the position where the first straight section is located when the medium has been transported by the predetermined amount without transport errors in the second step as a first ideal position, after transporting the medium by the predetermined amount, the first straight section having a first straight section which constitutes the detection pattern and is parallel to the first straight section The invention is characterized by the following steps: a third step of forming a second pattern having a second straight section on the medium by the printing unit at a position where at least a part of the second straight section overlaps with the first straight section located at the first ideal position when viewed from the width direction, and at a position where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction; a fourth step of moving the sensor so as to cross the overlapping portion where the first straight section located at the first ideal position and the second straight section overlap in the width direction, and detecting a first intersection point where the first straight section and the sensor intersect, and a second intersection point where the second straight section and the sensor intersect; and a fifth step of calculating the transport error of the medium in the second step based on the first and second intersection points detected in the fourth step, and correcting the amount of the medium transported by the transport unit.

[0025] According to this embodiment, a sensor is used that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging liquid onto the medium. By detecting the detection pattern before and after transporting a predetermined amount of medium, the transport error is calculated, and the amount of medium transported by the transport unit is corrected. In this way, by using a small sensor movable in a width direction perpendicular to the transport direction to detect the detection pattern and calculate the transport error, the risk of increased drive load and increased equipment costs can be reduced. Furthermore, the detection pattern can be printed and the sensor can automatically correct the transport error of the medium, reducing the risk of time and effort required for detecting and correcting transport errors.

[0026] Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. First, an overview of a printing apparatus 1 as one embodiment of the present invention will be described with reference to Figures 1 to 4. As shown in Figure 1, the printing apparatus 1 of this embodiment includes a setting unit 2 for setting a roll-shaped medium P, a winding unit 5 for winding up the medium P conveyed from the setting unit 2, and a carriage 8 having a print head 3 as a printing unit that ejects liquid ink onto the printing surface P1 of the medium P conveyed in the conveying direction T along the conveying path from the setting unit 2 to the winding unit 5 to form an image. As shown in Figures 3 and 4, the carriage 8 is provided with a sensor S, which will be described in detail later.

[0027] Furthermore, the printing apparatus 1 of this embodiment includes a platen 4 that supports the medium P in the image forming region where the image is formed by the print head 3, and a plurality of rollers 6 provided in the transport path of the medium P. The rollers 6 constitute a transport unit that transports the medium P in the transport direction T. In addition, the printing apparatus 1 of this embodiment includes a control unit 7 which has a CPU 7a and a storage unit 7b, and each component of the printing apparatus 1 of this embodiment is driven by the control unit 7. The control unit 7 can receive information about the medium P to be used from an external computer connected to the printing apparatus 1 of this embodiment.

[0028] The print head 3 is located on the side of the medium P that is transported in the transport direction T that is facing the printing surface P1. With the back surface P2 of the medium P, opposite to the printing surface P1, supported by the platen 4, ink is ejected onto the printing surface P1 to form an image. More specifically, the printing apparatus 1 of this embodiment prints by moving the carriage 8 back and forth in the scanning direction along the transport direction T. More specifically, the printing apparatus 1 of this embodiment intermittently drives the medium P in the transport direction T (intermittent transport) and moves the carriage 8 back and forth in the scanning direction (transport direction T), ejecting ink from the print head 3 to print.

[0029] In this embodiment, the print head 3 can complete the image formation of the entire image-forming region supported by the platen 4 on the printing surface P1, for example, a frame F corresponding to the printing region in one intermittent transport as shown in Figure 5, in a single scan (1 pass). Alternatively, image formation can also be completed by performing multiple scans (multiple passes) of the region corresponding to frame F. Compared to completing image formation in a single pass, completing image formation in multiple passes naturally increases the transport stop time of the medium P associated with intermittent transport.

[0030] As shown in Figure 4, the carriage 8 of this embodiment includes a drive unit 31 that moves the print head 3 inside the carriage 8 in the width direction W, which is perpendicular to the transport direction T. A sensor S is also provided at a position connected to the region 32 on which the print head 3 is mounted, and the sensor S can detect the edge of the medium P. Since the region 32 can move in the width direction W by driving the drive unit 31, the sensor S can also move in the width direction.

[0031] In this embodiment, the printing apparatus 1 uses sensors S to detect the transport error E of the transported medium P. The carriage 8 in this embodiment is equipped with three sensors S, as shown in Figure 4. There are three sensors S because the drive stroke of the region 32 is short relative to the width of the medium P to be detected. The printing apparatus 1 in this embodiment can detect the detection pattern ID, which will be described later, using at least one of the three sensors S.

[0032] As described above, the printing apparatus 1 of this embodiment includes a plurality of rollers 6 that transport the medium P in the transport direction T, a print head 3 that ejects liquid ink onto the medium P transported by the rollers 6, a sensor S that is movable in the width direction W perpendicular to the transport direction T and capable of detecting a detection pattern ID formed by ejecting ink onto the medium P, and a control unit 7. The control unit 7 can then correct the transport error E of the medium P based on the detection result of the detection pattern ID by the sensor S.

[0033] Next, we will explain the method for detecting the transport error E. Figure 5 shows an image pattern that includes the image I to be printed on the medium P in the actual print, and the detection pattern ID placed at the leading and trailing ends of the frame F. In the transport direction T, the downstream side is called the leading end of the frame F, and the upstream side is called the trailing end of the frame F. In this embodiment, the first pattern ID1, which is the detection pattern ID, has a first straight line section 111, which is a straight line section that intersects with both the transport direction T and the width direction W. The second pattern ID2, which is printed following the first pattern ID1 and will be described later, has a second straight line section 112, which is a straight line section that intersects with both the transport direction T and the width direction W. Here, the actual print is the final print of the target image I, and the trial print is a print for adjustment before the actual print.

[0034] Here, the amount of media P transported corresponding to the length T in the transport direction of frame F is determined by the size and arrangement of the image I that is actually printed, so let's call that amount (length T in the transport direction of frame F) A. Then, the leading and trailing ends of the printed image I are given detection pattern IDs of the same shape. At that time, the detection pattern IDs at the leading end and the detection pattern IDs at the trailing end are offset in the width direction W. Let's call this distance in the width direction W C. Here, distance C corresponds to the reference distance, which is the theoretical value in the width direction W between the first straight section 111 and the second straight section 112 calculated from the image data. Also, let's call the length of the detection pattern ID in the transport direction T D.

[0035] Next, using the flowchart in Figure 6 and referring to Figure 5, a printing method will be described in which a transport error E is calculated by continuously forming frames F on which a detection pattern ID is formed, and a transport error E is corrected. First, as shown in step S110, the control unit 7 calculates the amount of transported medium P as a theoretical value based on the size and arrangement of the image I to be printed.

[0036] Next, in step S120, before transporting the medium P corresponding to frame F1 as frame F, a first pattern ID1, as shown in the image pattern in Figure 5, is printed. Here, the upper part of Figure 7 shows the state after the completion of step S120. In the upper part of Figure 7, the detection pattern ID is printed at both the leading and trailing ends of frame F1 in the first pattern ID1, but the detection pattern ID may be printed only at the trailing end.

[0037] After step S120 is completed, step S130 is performed to transport the medium P corresponding to frame F1, i.e., to feed the frame. Here, the middle diagram of Figure 7 shows the state after step S130 is completed. In step S130, the amount of medium P transported is set to AD such that the detection pattern ID at the rear end formed by printing the first pattern ID1 before frame feeding and the detection pattern ID at the front end formed by printing the second pattern ID2 after frame feeding (step S140, described later) overlap when viewed from the width direction W.

[0038] After step S130 is completed, step S140 prints the second pattern ID2, which is the same image pattern as the first pattern ID1. By executing step S140, the detection pattern ID at the rear end of the first pattern ID1 before frame feeding and the detection pattern ID at the front end of the second pattern ID2 are printed at the same position in the transport direction T. The lower part of Figure 7 shows the state after step S140 is completed. Note that in the lower part of Figure 7, the detection pattern ID is printed at both the front and rear ends of frame F2 in the second pattern ID2, but it is also possible to print the detection pattern ID only at the front end.

[0039] After the detection pattern ID of the tip of the second pattern ID2 is printed in step S140, in step S150, the control unit 7 controls the drive of the drive unit 31 to move the position of the sensor S of the carriage 8 in the transport direction T to a position where the detection pattern ID of the rear end of the first pattern ID1 and the detection pattern ID of the tip of the second pattern ID2 overlap in the transport direction T, as shown in Figure 8. Then, in step S160, the sensor S is scanned in the width direction W to detect the detection pattern ID of the rear end of the first pattern ID1 and the detection pattern ID of the tip of the second pattern ID2.

[0040] In step S190, following step S160, the control unit 7 obtains the distance B between the detected pattern ID at the trailing end of the first pattern ID1 and the detected pattern ID at the leading end of the second pattern ID2, based on the detection results from the sensor S in step S160, and calculates the transport error E from the distance B. Then, in step S200, the control unit 7 determines the transport amount taking the transport error E into account, that is, corrects the transport error E, and in step S210, prints the image pattern of the print job that will be the main print. Note that the printing of the image pattern in steps S120 and S140 corresponds to the temporary printing before the main print in step S210.

[0041] As described above, the printing apparatus 1 of this embodiment can control the control unit 7 to perform the following steps. As the first step, it can perform step S120 in which the print head 3 forms a first pattern ID1 on the medium P, which is shown in the upper part of Figure 7 and has a first straight section 111 which is a straight section that constitutes a detection pattern ID and intersects both the transport direction T and the width direction W.

[0042] Furthermore, as a second step, as shown in the middle section of Figure 7, step S130 can be performed in which, after forming the first pattern ID1, a predetermined amount of medium P is conveyed by the roller 6. Here, the predetermined amount is the value AD obtained by subtracting the length D of the detected pattern ID in the conveying direction T from the length A of the frame F in the conveying direction T.

[0043] Furthermore, as a third step, step S140, shown in the lower part of Figure 7, can be executed. Specifically, when the position where the first straight section 111 is located when the medium P is transported by a predetermined amount without causing a transport error E in step S130 is defined as the first ideal position, after transporting the medium P by a predetermined amount, the print head 3 forms a second pattern ID2 on the medium P at a position where at least a part of the second straight section 112 overlaps with the first straight section 111 located at the first ideal position when viewed from the width direction W, and where there is a gap between the first straight section 111 located at the first ideal position and the second straight section 112 in the width direction W.

[0044] Furthermore, steps S150 and S160 can be performed as a fourth step. In steps S150 and S160, the sensor S is moved across the overlapping portion where the first straight section 111 and the second straight section 112, which are located at the first ideal position when viewed from the width direction W, overlap in the width direction W, and the first intersection point X1 (see Figure 8), which is the position where the first straight section 111 and the sensor S intersect, and the second intersection point X2 (see Figure 8), which is the position where the second straight section 112 and the sensor S intersect, are detected.

[0045] Furthermore, as a fifth step, steps S190 to S210 can be executed. In steps S190 to S210, the transport error E that occurred in the transport of the medium P in step S130 is calculated based on the first intersection X1 and the second intersection X2 detected in step S160, and the amount of medium P transported by the rollers 6 is corrected.

[0046] As described above, the printing apparatus 1 of this embodiment is equipped with a sensor S that is movable in the width direction W perpendicular to the transport direction T and capable of detecting a detection pattern ID formed by ejecting ink onto the medium P. By detecting the detection pattern ID, the transport error E that occurs before and after transporting a predetermined amount of medium P is calculated and the amount of medium P transported by the rollers 6 is corrected. In this way, by using a small sensor S that is movable in the width direction W perpendicular to the transport direction T to detect the detection pattern ID and calculate the transport error E, the risk of increased drive load and increased equipment costs can be reduced. Furthermore, by printing the detection pattern ID, the transport error E that occurs during the transport of medium P can be automatically corrected by the sensor S, reducing the risk of time and effort required to detect and correct the transport error E.

[0047] Next, referring to Figure 8, we will explain the principle by which the transport error E associated with frame feeding can be calculated by obtaining the distance B between the detected pattern ID at the rear end of the first pattern ID1 and the detected pattern ID at the front end of the second pattern ID2. Here, the first pattern ID1-1, represented by the solid line in Figure 8, represents the case where the transport amount associated with frame feeding is appropriate. In this case, the measured distance B1, which is the distance B between the detected pattern ID at the rear end of the first pattern ID1 and the detected pattern ID at the front end of the second pattern ID2, is equal to the distance C, which is the reference distance corresponding to the theoretical value calculated from the image data.

[0048] The first pattern ID1-2 in Figure 8 represents the case where the amount of material transported during frame feeding is greater than the appropriate amount. When the amount of material transported during frame feeding is greater than the appropriate amount, the first pattern ID1-2, represented by the dashed line, is positioned on the direction of travel side (right side in the figure) in the transport direction T compared to the second pattern ID2. Here, since the first straight section 111 and the second straight section 112 detected by the sensor S are inclined with respect to the transport direction T, the measured distance B2, which is the distance B between the detected pattern ID at the rear end of the first pattern ID1 and the detected pattern ID at the front end of the second pattern ID2, is greater than the reference distance C.

[0049] Here, the transport error E2 corresponding to the first pattern ID1-2 can be expressed as (B2-C)tanθ, where θ is the inclination of the first straight section 111 and the second straight section 112 from the width direction W in the extension direction, and B2 is the distance B in this case, as well as C is the reference distance. For example, if the first straight section 111 and the second straight section 112 are inclined at 45° with respect to the width direction W, that is, if tanθ is 1, the transport error E2 can be calculated as B2-C.

[0050] On the other hand, the first pattern ID1-3 in Figure 8 represents the case where the amount of material transported with frame feeding is smaller than the appropriate amount of material transported. When the amount of material transported with frame feeding is smaller than the appropriate amount of material transported, the first pattern ID1-3, represented by the dashed line, is positioned on the opposite side of the direction of travel in the transport direction T (left side in the figure) compared to the second pattern ID2. Furthermore, the measured distance B3, which is the distance B between the detection pattern ID at the rear end of the first pattern ID1 and the detection pattern ID at the front end of the second pattern ID2, is smaller than the reference distance C. In addition, the transport error E3 corresponding to the first pattern ID1-3 can be expressed as (B3-C)tanθ, where θ is the slope from the width direction W in the extension direction of the first straight section 111 and the second straight section 112, and the distance B3 and the reference distance C are used.

[0051] To explain the above from a different perspective, in the fifth step, from step S190 to step S210, the printing apparatus 1 of this embodiment calculates the transport error E as (BC)tanθ, where B is the distance in the width direction W between the position of the first intersection X1 and the position of the second intersection X2, C is the theoretical reference distance in the width direction W between the first straight section 111 and the second straight section 112, and θ is the angle obtained by subtracting the inclination of the first straight section 111 with respect to the transport direction T from 90 degrees. By calculating the transport error E in this way, the transport error E can be calculated accurately and easily. Note that by setting the transport error E to (BC)tanθ, the corrected transport amount (frame feed amount) becomes A - {(BC)tanθ}.

[0052] In this embodiment, the length of the detection area of ​​the sensor S in the transport direction T of the printing apparatus 1 is configured to be shorter than the length of the overlap between the first straight section 111 and the second straight section 112, which are located at the first ideal position when viewed from the width direction W in the transport direction T. This configuration eliminates the need for a large sensor like a line scanner, allowing for a particularly miniaturized sensor. Therefore, the printing apparatus 1 of this embodiment can effectively suppress increases in drive load and equipment costs.

[0053] The printing apparatus 1 of this embodiment can use various media P. The storage unit 7b provided in the control unit 7 stores the types of media P that can be selected as media P and the transport error E corresponding to each type of media P in association. Here, when the control unit 7 starts printing, if the transport error E corresponding to the type of media P to be used is not stored in the storage unit 7b, it is configured to perform the above steps 1 to 5, i.e., steps S110 to S210, to calculate the transport error E corresponding to the type of media P to be used. In other words, if the printing apparatus 1 of this embodiment has data in the storage unit 7b that associates the type of media P with the corresponding transport error E, steps S110 to S190 can be omitted and the transport error E can be calculated based on that data. With this configuration, the printing apparatus 1 of this embodiment can simplify the transport error E correction process when using previously used media P again.

[0054] Furthermore, in the printing apparatus 1 of this embodiment, if there is no data in the storage unit 7b that associates the type of medium P with the corresponding transport error E, such as when a new medium P is used, the control unit 7 can calculate the transport error E corresponding to the type of medium P to be used, and then store the type of medium P to be used and the calculated transport error E in association with each other in the storage unit 7b. With this configuration, the printing apparatus 1 of this embodiment can increase the number of types of medium P for which the transport error E correction process can be simplified.

[0055] On the other hand, in the printing apparatus 1 of this embodiment, the control unit 7 can also perform the above-mentioned first to fifth steps, i.e., steps S110 to S210, each time a print job is executed to calculate the transport error E. The degree of swelling and shrinking of the medium P may change depending on the operating environment of the printing apparatus 1, but the printing apparatus 1 of this embodiment has such a configuration that it corrects the transport error E each time a print job is executed, so it can accurately correct the transport error E regardless of the operating environment of the printing apparatus 1.

[0056] In step S120 of this embodiment, the printing apparatus 1 can form the first pattern ID1 on the medium P by printing image data obtained by combining the image data of image I to be printed in the print job and the image data of the first pattern ID1 onto the medium P, as shown in Figure 5. Similarly, in step S140 of this embodiment, the printing apparatus 1 can form the second pattern ID2 on the medium P by printing image data obtained by combining the image data of image I to be printed in the print job and the image data of the second pattern ID2 onto the medium P. With this configuration, the printing apparatus 1 of this embodiment can correct the transport error E by taking into account the degree of swelling and shrinkage of the medium P due to the amount of ink adhering as the image is printed in the print job. Note that in the combination of the image data of image I and the image data of the first pattern ID1 and the image data of the second pattern ID2, the image data of image I located around the first pattern ID1 and the second pattern ID2 may be deleted before combination. In this way, the risk of the detection accuracy of the pattern ID being reduced by the image data of image I can be avoided.

[0057] Furthermore, the printing apparatus 1 of this embodiment is configured to also form patterns other than the first pattern ID1 consisting only of the first straight section 111 and the second pattern ID2 consisting only of the second straight section 112, as shown in Figures 7 and 8. From another perspective, the printing apparatus 1 of this embodiment can correct the transport amount more accurately by changing the first pattern ID1 and the second pattern ID2 and detecting the first pattern ID1 and the second pattern ID2 by the sensor S twice.

[0058] In configurations such as the printing apparatus 1 of this embodiment, which includes a setting section 2 for setting a roll-shaped medium P and a winding section 5 for winding the medium P conveyed from the setting section 2 into a roll shape, the medium P may be conveyed at an angle. In the printing apparatus 1 of this embodiment, there is a risk that the medium P will be conveyed at an angle on the platen 4. The ease of conveying at an angle varies depending on the width of the medium P used, and the medium P may be conveyed at an angle due to uneven tension applied to the medium P along the conveying direction T. When the medium P is conveyed at an angle, it is generally difficult to accurately correct the conveying amount.

[0059] However, the printing apparatus 1 of this embodiment can accurately correct the transport amount even when the medium P is transported at an angle. As a method for doing so, the first pattern ID1 and the second pattern ID2 are given the shapes shown in Figure 9. Below, a printing method for accurately correcting the transport amount by printing the first pattern ID1 and the second pattern ID2 with the shapes shown in Figure 9 will be explained using the flowchart in Figure 10 with reference to Figure 9. Here, Figure 9 corresponds to Figure 8, and Figure 10 corresponds to Figure 7. Note that in the flowchart in Figure 10, explanations of the same steps as in the flowchart in Figure 7 will be simplified and omitted.

[0060] In the printing method shown in the flowchart of Figure 10, step S110 of the flowchart in Figure 7 is omitted, and the process starts from the same steps as step S120 of the flowchart in Figure 7. However, the shape of the first pattern ID1 printed here is the first pattern ID1 shown in Figure 9. Specifically, the first pattern ID1 has a first straight section 111 and a third straight section 113 that extends parallel to the transport direction T.

[0061] In the printing method shown in the flowchart of Figure 10, after the completion of step S120, a predetermined amount of media is transported in step S130, and then step S140 is executed. The shape of the second pattern ID2 printed in step S140 of the flowchart of Figure 10 is the same as the second pattern ID2 shown in Figure 9. Specifically, the second pattern ID2 has a second linear section 112, as well as a fourth linear section 114 that extends parallel to the transport direction T.

[0062] The subsequent steps S150 and S160 are the same as in the flowchart of Figure 7. That is, the distance B in the width direction W between the first straight section 111 and the second straight section 112 is measured. As in the flowchart of Figure 7, if the amount of material transported with frame feeding is too long, it will be longer than the distance B1 when the amount of material transported is appropriate, as shown by distance B2. If the amount of material transported with frame feeding is too short, it will be shorter than the distance B1 when the amount of material transported is appropriate, as shown by distance B3.

[0063] In the printing method shown in the flowchart of Figure 10, after the completion of step S160, in step S170, the control unit 7 controls the drive of the drive unit 31 to move the position of the sensor S of the carriage 8 in the transport direction T to the position of the third linear section 113 of the first pattern ID1 and the position of the fourth linear section 114 of the second pattern ID2, as shown in Figure 9. Then, in step S180, the sensor S is scanned in the width direction W to detect the third linear section 113 of the first pattern ID1 and the fourth linear section 114 of the second pattern ID2.

[0064] In step S190, following step S180, the control unit 7 obtains the distance B between the first straight section 111 of the first pattern ID1 and the second straight section 112 of the second pattern ID2 that were actually printed, and the distance G between the third straight section 113 of the first pattern ID1 and the fourth straight section 114 of the second pattern ID2 that were actually printed, based on the detection results from the sensor S in steps S160 and S180. The control unit 7 then calculates the transport error E from distances B and G. Here, distance G is a constant value whether the transport amount is appropriate, as represented by distance G1, or whether the transport amount is inappropriate, as represented by distances G2 and G3. Distance G1 corresponds to the first pattern ID1-1, distance G2 corresponds to the first pattern ID1-2, and distance G3 corresponds to the first pattern ID1-3. However, if there is skewed transport, distance G will differ depending on the degree of skew. Therefore, in step S190, the degree of skew is calculated from distance G, and then the transport error E is calculated from distance B. Then, steps S200 and S210 are executed, similar to the flowchart in Figure 7, to complete the printing method shown in the flowchart in Figure 10.

[0065] More specifically, as shown in Figure 9, in step S140, which corresponds to the third step, the fourth straight section 114 is formed such that at least a portion of the fourth straight section 114 overlaps with the third straight section 113, which is located at the first ideal position (corresponding to the first pattern ID1-1) when viewed from the width direction W, and there is a gap (corresponding to distance G1) between the third straight section 113, which is located at the first ideal position in the width direction W, and the fourth straight section 114. Then, in steps S170 and S180, which are between the third step (step S140) and the fifth step (step S190), the control unit 7 of the printing apparatus 1 in this embodiment performs a sixth step in which it moves the sensor S across the overlapping portion where the third straight section 113 and the fourth straight section 114, which are located at the first ideal position when viewed from the width direction W, intersects the third intersection X3, which is the position where the third straight section 113 and the sensor S intersect, and the fourth intersection X4, which is the position where the fourth straight section 114 and the sensor S intersect. Furthermore, in the fifth step (step S190), instead of the reference distance C calculated in step S110, the distance G in the width direction W between the third intersection X3 and the fourth intersection X4 is used. By correcting the amount of media P transported in this way, the amount of media P transported can be accurately corrected based on measured values, even if, for example, skewed transport occurs.

[0066] The present invention is not limited to the embodiments described above, and can be realized in various configurations without departing from its spirit. For example, the technical features in the embodiments corresponding to the technical features in each embodiment described in the summary of the invention can be replaced or combined as appropriate in order to solve some or all of the above-described problems, or to achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be deleted as appropriate. [Explanation of symbols]

[0067] 1…Printing device, 2…Setting unit, 3…Print head (printing unit), 4…Platen, 5…Winding unit, 6…Roller (conveying unit), 7…Control unit, 7a…CPU, 7b…Storage unit, 8…Carriage, 31…Drive unit, 32…Area, 111…First straight section, 112…Second straight section, 113…Third straight section, 114…Fourth straight section, A…Length, B…Distance, B1…Distance, B2…Distance, B3…Distance, C…Distance, D…Length, E… Transport error, E2… Transport error, E3… Transport error, F… Frame, F1… Frame, F2… Frame, G… Distance, G1… Distance, G2… Distance, G3… Distance, I… Image, ID… Detection pattern, ID1… First pattern, ID2… Second pattern, P… Medium, P1… Printed side, P2… Back side, S… Sensor, T… Transport direction, W… Width direction, X1… First intersection, X2… Second intersection, X3… Third intersection, X4… Fourth intersection

Claims

1. A transport unit that transports the medium in the transport direction, A printing unit that dispenses liquid onto the medium being transported by the transport unit, A sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging the liquid into the medium, Control unit and Equipped with, The control unit, A first step of controlling the printing unit to form a first pattern on the medium, which has a first straight section that constitutes the detection pattern and intersects both the transport direction and the width direction, After forming the first pattern, a second step is to control the transport unit to transport a predetermined amount of the medium, In the second step, when the position where the first straight section is located when the medium has been transported by a predetermined amount without transport errors is defined as the first ideal position, the third step involves controlling the printing section to form a second pattern on the medium after the medium has been transported by the predetermined amount, the second pattern having a second straight section which constitutes the detection pattern and is a single straight section parallel to the first straight section, at a position where at least a part of the second straight section overlaps with the first straight section located at the first ideal position when viewed from the width direction, and where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction. A fourth step involves moving the sensor so as to cross the overlapping portion where the first straight section and the second straight section, which are located at the first ideal position when viewed from the width direction, overlap in the width direction, and detecting a first intersection point, which is the position where the first straight section and the sensor intersect, and a second intersection point, which is the position where the second straight section and the sensor intersect. A printing apparatus characterized by performing a fifth step of calculating the transport error of the medium in the second step based on the first and second intersections detected in the fourth step, and correcting the amount of medium transported by the transport unit.

2. In the printing apparatus described in claim 1, A printing apparatus characterized in that, in the fifth step, B is the distance in the width direction between the position of the first intersection and the position of the second intersection, C is the theoretical reference distance in the width direction between the first straight section and the second straight section, and θ is the angle obtained by subtracting the inclination of the first straight section with respect to the transport direction from 90 degrees, and the transport error is calculated as (B - C) tanθ.

3. In the printing apparatus described in claim 2, The first pattern has a third straight section which is a straight section parallel to the conveying direction, The second pattern has a fourth straight section which is a straight section parallel to the conveying direction, In the third step, the fourth straight section is formed such that at least a portion of the fourth straight section overlaps with the third straight section located at the first ideal position when viewed from the width direction, and there is a gap between the third straight section located at the first ideal position and the fourth straight section in the width direction. The control unit, Between the third and fifth steps, a sixth step is performed in which the sensor is moved in the width direction to cross the overlapping portion where the third straight section and the fourth straight section, which are located at the first ideal position when viewed from the width direction, overlap, and a third intersection point, which is the position where the third straight section and the sensor intersect, and a fourth intersection point, which is the position where the fourth straight section and the sensor intersect, are detected. A printing apparatus characterized in that, in the fifth step, the distance in the width direction between the third intersection and the fourth intersection is used instead of the reference distance.

4. In the printing apparatus described in claim 1 or 2, A printing apparatus characterized in that the length of the detection area of ​​the sensor in the transport direction is shorter than the length of the overlapping portion in the transport direction.

5. In the printing apparatus described in claim 1 or 2, The system includes a storage unit that stores, in association with the types of media that can be selected as the media, and the transport error corresponding to each of the media types. The printing apparatus is characterized in that, when the control unit starts printing, if the transport error corresponding to the type of medium to be used is not stored in the storage unit, it performs the first to fifth steps to calculate the transport error corresponding to the type of medium to be used.

6. In the printing apparatus described in claim 5, The printing apparatus is characterized in that the control unit calculates the transport error corresponding to the type of medium used, and then stores the calculated transport error in association with the type of medium used in the storage unit.

7. In the printing apparatus described in claim 1 or 2, The printing apparatus is characterized in that the control unit performs the first to fifth steps each time a print job is executed and calculates the transport error.

8. In the printing apparatus described in claim 1 or 2, In the first step, the first pattern is formed on the medium by printing image data obtained by combining the image data to be printed in the print job and the image data of the first pattern onto the medium. The printing apparatus is characterized in that, in the third step, it forms a second pattern on the medium by printing image data obtained by combining the image data to be printed in the print job and the image data of the second pattern onto the medium.

9. A transport unit that transports the medium in the transport direction, A printing unit that dispenses liquid onto the medium being transported by the transport unit, A sensor that is movable in a width direction perpendicular to the transport direction and capable of detecting a detection pattern formed by discharging the liquid into the medium, A printing method for a printing apparatus equipped with, A first step is to form a first pattern on the medium using the printing unit, the first pattern having a first straight section which is a straight section that constitutes the detection pattern and intersects both the transport direction and the width direction, After forming the first pattern, a second step is to transport a predetermined amount of the medium using the transport unit, In the second step, when the position where the first straight section is located when the medium has been transported by a predetermined amount without transport errors is defined as the first ideal position, the third step is to form a second pattern on the medium by the printing unit after the medium has been transported by the predetermined amount, the second pattern having a second straight section which constitutes the detection pattern and is a single straight section parallel to the first straight section, at a position where at least a part of the second straight section overlaps with the first straight section located at the first ideal position when viewed from the width direction, and where there is a gap between the first straight section located at the first ideal position and the second straight section in the width direction. A fourth step involves moving the sensor so as to cross the overlapping portion where the first straight section and the second straight section, which are located at the first ideal position when viewed from the width direction, overlap in the width direction, and detecting a first intersection point, which is the position where the first straight section and the sensor intersect, and a second intersection point, which is the position where the second straight section and the sensor intersect. A printing method characterized by performing a fifth step of calculating the transport error of the medium in the second step based on the first and second intersections detected in the fourth step, and correcting the amount of the medium transported by the transport unit.

Images