Recording device, recording reading system, and recording method

Abstract

To provide a technique useful for detecting foreign matters while suppressing cost.SOLUTION: A recording device comprises a first nozzle array and a second nozzle array, and a control part which controls liquid discharge by the first nozzle array and the second nozzle array. The control part can cause the first nozzle array and the second nozzle array to perform scanning for discharging liquid while moving on an approach route or a return route along a main scanning direction, records a first pattern that has a first overlapping region which is an overlapping region where a raster line with the main scanning direction as a longer direction is formed by m-time scanning and a first normal region which is a normal region where a raster line is formed by n-time scanning less than m times, onto a medium by controlling the first nozzle array, and forms the first overlapping region at a position overlapping a second normal region when viewed from the longer direction when recording a second pattern that has a second overlapping region which is an overlapping region and the second normal region which is a normal region, on the medium by controlling the second nozzle array.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a recording device, a recording / reading system, and a recording method. [Background technology]

[0002] The recorded material output by the printer is optically read by a reading device, allowing the color, density, etc. of the recorded material to be acquired and evaluated. At this time, if dust or other foreign matter is attached to the reading device, the reading results of the foreign matter will be mixed into the data obtained as the reading result of the recorded material, making it impossible to read the recorded material accurately.

[0003] In addition, an image forming device has been disclosed that uses a colorimeter that can read only a partial area in the main scanning direction and a line sensor that can read across the image formation width in the main scanning direction to read the same side of the same paper inline after image formation, and detects the presence or absence of abnormal values ​​based on the reading information read by the line sensor, and if abnormal values ​​are detected a predetermined number of times or more at the same location in the main scanning direction where an abnormal value was detected, displays a message urging the user to clean the line sensor and colorimeter (see Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-225285 Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned document 1, a line sensor is required to clean foreign matter adhering to the colorimeter, and there is a problem in that the cost increases due to the provision of two image reading sensors. In view of this situation, there is a demand for a technology that helps detect foreign matter adhering to image reading sensors while suppressing costs. [Means for solving the problem]

[0006] The recording device includes a first nozzle row and a second nozzle row consisting of a plurality of nozzles that eject liquid onto a medium, and a control unit that controls the ejection of the liquid by the first nozzle row and the second nozzle row. The control unit is capable of causing the first nozzle row and the second nozzle row to perform a scan in which the liquid is ejected while moving forward or backward along a predetermined main scanning direction. The control unit controls the first nozzle row to record a first pattern on the medium, the first pattern having a first overlapping region, which is an overlapping region in which a raster line having the main scanning direction as its longitudinal direction is formed by m scans, and a first normal region, which is a normal region in which the raster line is formed by n scans, which is less than m scans. The control unit controls the second nozzle row to record a second pattern on the medium, the second pattern having a second overlapping region, which is the overlapping region, and a second normal region, which is the normal region, so that the first overlapping region is formed at a position that overlaps with the second normal region when viewed from the longitudinal direction.

[0007] The recording device includes a first nozzle row, a second nozzle row, a third nozzle row, and a fourth nozzle row, each of which is a nozzle row in which a plurality of nozzles for ejecting liquid onto a medium are aligned in a direction in which the nozzles are aligned, and a control unit capable of controlling the ejection of the liquid by the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row, and the control unit controls the first nozzle row and the second nozzle row to form a first normal region in which a raster line having a longitudinal direction intersecting the direction in which the nozzles are aligned is formed using the first nozzle row or the second nozzle row, and a second normal region in which a raster line having a longitudinal direction intersecting the direction in which the nozzles are aligned is formed using the first nozzle row or the second nozzle row. a first pattern having a first overlapping region where the raster lines are formed using the first nozzle row and the second nozzle row, and a second pattern having a second normal region where the raster lines are formed using the third nozzle row or the fourth nozzle row and a second overlapping region where the raster lines are formed using the third nozzle row and the fourth nozzle row is recorded on the medium by controlling the third nozzle row and the fourth nozzle row, so that the first overlapping region is formed at a position overlapping with the second normal region when viewed from the longitudinal direction.

[0008] The recording and reading system includes the recording device, a reading unit that reads the first pattern and the second pattern recorded on the medium by the recording device, and a detection unit that detects foreign matter in the reading unit based on the results of reading the first pattern and the second pattern by the reading unit.

[0009] A recording method using a recording device that performs recording by controlling the ejection of liquid by a first nozzle row and a second nozzle row consisting of a plurality of nozzles that eject the liquid onto a medium includes a pattern recording step of causing the first nozzle row and the second nozzle row to perform scans that eject the liquid while moving forward or backward along a predetermined main scanning direction to record a pattern on the medium, wherein in the pattern recording step, by controlling the first nozzle row, a first pattern is recorded on the medium, the first pattern having a first overlapping region that is an overlapping region in which raster lines with the main scanning direction as their longitudinal direction are formed by m scans, and a first normal region that is a normal region in which the raster lines are formed by n scans, which is less than m, and by controlling the second nozzle row, when a second pattern is recorded on the medium, the second overlapping region being the overlapping region, and a second normal region being the normal region, the first overlapping region is formed at a position that overlaps with the second normal region when viewed from the longitudinal direction.

[0010] A recording method for a recording device that performs recording by controlling the ejection of liquid from a first nozzle row, a second nozzle row, a third nozzle row, and a fourth nozzle row, each of which is a nozzle row having a plurality of nozzles that eject liquid onto a medium aligned in a direction in which the nozzles are aligned, includes a pattern recording step of causing the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row to eject the liquid and recording a pattern on the medium, wherein in the pattern recording step, by controlling the first nozzle row and the second nozzle row, a raster line having a longitudinal direction that intersects with the direction in which the nozzles are aligned is formed by the first nozzle row or the second nozzle row. a first pattern having a first normal area formed using a nozzle row and a first overlap area in which the raster lines are formed using the first nozzle row and the second nozzle row, and by controlling the third nozzle row and the fourth nozzle row, a second pattern having a second normal area formed using the raster lines using the third nozzle row or the fourth nozzle row and a second overlap area in which the raster lines are formed using the third nozzle row and the fourth nozzle row is recorded on the medium, and the first overlap area is formed at a position overlapping with the second normal area when viewed from the longitudinal direction. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a block diagram showing a simplified system configuration of the present embodiment. [Figure 2] FIG. 2 is a diagram simply showing the relationship between the recording head and the medium according to the first example from an overhead perspective. [Figure 3] FIG. 10 is a simplified diagram showing the relationship between a recording head and a medium according to a second example, viewed from above. [Figure 4] FIG. 11 is a simplified diagram showing the relationship between a recording head and a medium according to a third example, viewed from above. [Figure 5] FIG. 10 is a simplified diagram showing the relationship between a recording head and a medium according to a fourth example, viewed from above. [Figure 6] 10 is a flowchart showing the flow of pattern recording and foreign matter detection. [Figure 7]FIG. 10 is a simplified view showing the medium and the reading unit after a pattern has been recorded, as viewed from above. [Figure 8] 10A and 10B are diagrams showing an example of a density correction pattern, a portion of a comparison pattern, and a read result. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the drawings are merely examples for explaining the present embodiment. Because the drawings are examples, the proportions and shapes may not be accurate, the drawings may not match each other, and some parts may be omitted.

[0013] 1. System Overview: 1 shows a simplified configuration of a recording and reading system 1 according to this embodiment. The recording and reading system 1 may also be called a foreign substance detection system 1 or a data correction system 1. The recording and reading system 1 includes a recording device 10 and a reading device 30. The recording method of this embodiment is executed by the recording device 10.

[0014] The recording device 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a communication IF 15, a transport unit 16, a recording unit 17, a storage unit 18, etc. IF stands for interface. The control unit 11 includes one or more ICs having a CPU 11a as a processor, a ROM 11b, a RAM 11c, etc., and other non-volatile memories. In the control unit 11, the processor, i.e., the CPU 11a, executes arithmetic processing in accordance with a program 12 stored in the ROM 11b or other memory, etc., using the RAM 11c, etc., as a work area.

[0015] The control unit 11 realizes multiple functions such as a recording control unit 12a and a data correction unit 12b by following the program 12. These functions are only a part of the functions that the program 12 causes the control unit 11 to realize. Note that the processor is not limited to one CPU, and may be configured to perform processing using multiple CPUs or hardware circuits such as ASICs, or may be configured to perform processing in cooperation with a CPU and a hardware circuit.

[0016] The display unit 13 is a means for displaying visual information and is configured, for example, by a liquid crystal display, an organic electroluminescence (EL) display, or the like. The display unit 13 may be configured to include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving operations by a user and is realized, for example, by physical buttons, a touch panel, a mouse, a keyboard, or the like. Of course, the touch panel may be realized as one function of the display unit 13. The display unit 13 and the operation reception unit 14 may be collectively referred to as the operation panel of the recording device 10. The display unit 13 and the operation reception unit 14 may be part of the configuration of the recording device 10, or may be peripheral devices external to the recording device 10.

[0017] The communication IF 15 is a general term for one or more IFs that allow the recording device 10 to communicate with other devices via wired or wireless communication in accordance with a predetermined communication protocol, including a known communication standard. In the example of Fig. 1, the recording device 10 is connected to the reading device 30 via the communication IF 15. The recording device 10 can connect to and communicate with not only the reading device 30 but also various external devices not shown in Fig. 1 via the communication IF 15.

[0018] Conveying unit 16 is a means for conveying the recording medium in a predetermined conveying direction under the control of control unit 11, and includes, for example, rollers (not shown) that rotate to convey the medium, a motor for driving the rollers, etc. The medium is typically paper, but may be made of a material other than paper as long as it is a medium that can be recorded on with a liquid.

[0019] The recording unit 17 is a mechanism that ejects liquid such as ink using an inkjet method to perform recording on a medium. The recording unit 17 has a recording head 20, as described below. The recording head 20 has a plurality of nozzles 21 for ejecting liquid, and ejects the liquid from each nozzle 21 onto the medium 40 transported by the transport unit 16 under the control of the control unit 11. The droplets ejected from the nozzles 21 are also called dots. The recording head 20 may also be called a liquid ejection head, a print head, a printing head, an inkjet head, etc.

[0020] The storage unit 18 is, for example, a hard disk drive, a solid state drive, or other memory storage means. Part of the memory of the control unit 11 may be regarded as the storage unit 18. The storage unit 18 may also be regarded as part of the control unit 11.

[0021] The reading device 30 includes a control unit 31, a communication IF 32, a transport unit 33, a reading unit 34, a display unit 35, etc. The control unit 31, like the control unit 11, is equipped with a processor, memory, programs, etc., which work together to control the reading device 30. The communication IF 32 is a general term for one or more IFs that allow the reading device 30 to communicate with other devices via wire or wirelessly in accordance with a predetermined communication protocol including a known communication standard, and in the example of FIG. 1, it is connected to the communication IF 15 of the recording device 10.

[0022] The display unit 35 is a means for displaying visual information, similar to the display unit 13. Of course, the reading device 30 may also have an operation reception unit. The transport unit 33 is a means for transporting the document to be read in a predetermined transport direction under the control of the control unit 31, and includes, for example, rollers that rotate to transport the document and a motor for driving the rollers (not shown). The medium 40 after recording by the recording device 10 becomes a type of document for the reading device 30. Hereinafter, the document read by the reading device 30 may be referred to as the medium 40.

[0023] The reading unit 34 is a mechanism for optically reading the document conveyed by the conveying unit 33. While details are omitted, the reading unit 34 includes a light source that illuminates the document, an image sensor that receives reflected or transmitted light from the document through a predetermined reading surface and photoelectrically converts it to generate an electrical signal, and an image processing circuit that performs predetermined conversions and corrections on the electrical signal output by the image sensor to generate read image data as the document reading result. The image processing circuit may be part of the control unit 31. If foreign matter adheres to the reading surface of the reading unit 34 that faces the document, the document cannot be read correctly. The image sensor is a line sensor that is elongated in the width direction of the document and intersects the direction of document conveyance by the conveying unit 33. The line sensor is configured with multiple photoelectric conversion elements arranged along the width direction of the document. This reading device 30 is a sheet-fed type scanner.

[0024] The control unit 11, display unit 13, communication IF 15, and transport unit 16 of the recording device 10 and the control unit 31, display unit 35, communication IF 32, and transport unit 33 of the reading device 30 may be described as the first control unit 11, the first display unit 13, the first communication IF 15, the first transport unit 16, the second control unit 31, the second display unit 35, the second communication IF 32, and the second transport unit 33, respectively, for the convenience of identifying them.

[0025] The recording device 10 and the reading device 30 may be considered to be independent devices. In this case, the user places the medium 40 recorded by the recording device 10 into the conveying unit 33 of the reading device 30, and the recorded medium 40 is read by the reading unit 34.

[0026] Alternatively, the recording device 10 and the reading device 30 may be configured as an integrated unit. In other words, the recording / reading system 1 may be a single device including the recording device 10 and the reading device 30. In this case, the medium 40 after recording by the recording unit 17 is subsequently transported to the reading unit 34 and read by the reading unit 34. In other words, the reading unit 34 may be disposed inline downstream of the recording unit 17 in the transport direction.

[0027] When the recording device 10 and the reading device 30 are integrally configured, the conveying unit 16 and the conveying unit 33 are essentially an integrated conveying means, and it is not necessary to distinguish between them in understanding this embodiment. Similarly, the control unit 31 may be understood as part of the control unit 11, and the display unit 13 and the display unit 35 may be understood as the same entity. In the following description, the recording device 10 and the reading device 30 will be described without making any particular distinction as to whether they are independent devices or an integrated device.

[0028] 2. Description of the recording head and overlap area: Next, the features of the print head 20 in this embodiment and the printing of the overlapping area by the print head 20 will be described using first to fourth examples.

[0029] First example: FIG. 2 shows a simplified top view of the relationship between the recording head 20 and the medium 40 according to the first example. In FIG. 2, the recording head 20 is mounted on a carriage (not shown). In other words, the recording unit 17 includes the recording head 20 and the carriage. Alternatively, the recording head 20 may be considered to have the functionality of a carriage. The carriage is a mechanism that receives power from a motor and can move back and forth along a main scanning direction D2 that intersects with the direction D1 of transport of the medium 40 by the transport unit 16. Therefore, the recording head 20 moves forward and backward along the main scanning direction D2 using the carriage. The intersection of the transport direction D1 and the main scanning direction D2 may be considered to be orthogonal. However, the orthogonal does not have to be strictly orthogonal, and may be an intersection that includes errors that may occur in the product.

[0030] FIG. 2 shows the arrangement of nozzles 21 on the surface of the recording head 20 facing the medium 40. In FIGS. 2 to 5, circles represent individual nozzles 21. In a configuration in which ink of each color is supplied from a liquid holding means (not shown) called an ink cartridge or ink tank and ejected from the nozzles 21, the recording head 20 has a nozzle row for each ink color. FIG. 2 shows a nozzle row 23K for ejecting black (K) ink and a nozzle row 23C for ejecting cyan (C) ink. The nozzle row made up of a plurality of nozzles 21 that eject K ink is the nozzle row 23K, and the nozzle row made up of a plurality of nozzles 21 that eject C ink is the nozzle row 23C.

[0031] Each nozzle row is composed of a plurality of nozzles 21 arranged at a constant or nearly constant interval (nozzle pitch) in the transport direction D1. The direction in which the plurality of nozzles 21 constituting a nozzle row are arranged is referred to as the nozzle arrangement direction D3. While an example in which the nozzle arrangement direction D3 diagonally intersects the transport direction D1 is known as a configuration of the recording head 20, FIG. 2 shows an example in which the nozzle arrangement direction D3 is parallel to the transport direction D1. In FIG. 2, the plurality of nozzle rows are arranged along the main scanning direction D2 and are positioned at the same position in the transport direction D1. Here, the nozzle row 23K is referred to as the "first nozzle row" and the nozzle row 23C is referred to as the "second nozzle row." Although omitted for space reasons, the recording head 20 may naturally have nozzle rows other than the nozzle rows 23K and 23C. The recording head 20 may also have, for example, a nozzle row for ejecting magenta (M) ink, a nozzle row for ejecting yellow (Y) ink, a nozzle row for ejecting other inks or liquids other than ink, and so on.

[0032] 2, for convenience of explanation, each nozzle 21 constituting a nozzle row is assigned a nozzle number. Specifically, the N nozzles constituting one nozzle row are assigned nozzle numbers in order from downstream to upstream in the transport direction D1, such as #1, #2, #3, ... #N. In the first example, the nozzle rows are positioned in the same position in the transport direction D1, and therefore the nozzle numbers are information common to each nozzle row.

[0033] In the first example, the control unit 11 combines the so-called "paper feed" of the medium 40 from upstream to downstream in the transport direction D1 by the transport unit 16 with the "scan" of ink ejection from the recording head 20 as the recording head 20 moves forward and backward, thereby recording an image two-dimensionally on the medium 40 based on image data representing the image. In this way, the recording device 10 functions as a so-called serial printer. A scan is also called a "pass." The medium 40 remains stationary during a scan. Figure 2 shows one recording head 20 in two locations. That is, the recording head 20 is shown when performing a pass P1, and the recording head 20 is shown when performing a pass P2 following pass P1. The distance L1 in the transport direction D1 between the recording head 20 when performing pass P1 and the recording head 20 when performing pass P2 corresponds to the distance of one paper feed.

[0034] In Figure 2, it appears that the recording head 20 moves upstream in the transport direction D1 with each pass, but in reality, the medium 40 moves downstream in the transport direction D1 with each paper feed, causing the relative position between the recording head 20 and the medium 40 in the transport direction D1 to change. When a certain pass is called a preceding pass, the pass following that pass is called a following pass. Passes P1 and P2 have a relationship of preceding and following passes. Of course, from the perspective of the pass following pass P2, pass P2 is also a preceding pass. In this way, passes and paper feeds are repeated.

[0035] In the first example, a line recorded on medium 40 with the main scanning direction D2 as its longitudinal direction is called a "raster line." In the image data state, a raster line is a row of pixels in which multiple pixels are lined up in the main scanning direction D2. Also, on medium 40, a raster line is a row of dots facing in the main scanning direction D2. However, the length of the raster line does not matter.

[0036] When focusing on printing with ink of a certain color, one raster line can be printed by ejecting ink from one nozzle 21, i.e., in one scan, but the control unit 11 prints some raster lines using multiple nozzles 21, i.e., multiple scans. The method of printing raster lines with ink of one color using multiple nozzles 21 is called overlap (hereinafter, OL) printing.

[0037] As can be seen from Fig. 2, in the first example, the control unit 11 adjusts the distance L1 to overlap a portion of the area printed in the preceding pass with OL printing in the following pass. Specifically, in Fig. 2, paper is fed so that common areas 41 and 42 on the medium 40 can be printed using the nozzle range of nozzle numbers #N-5 to #N of the print head 20 in the preceding pass and the nozzle range of nozzle numbers #1 to #6 of the print head 20 in the following pass. In this way, the nozzle range of nozzle numbers #1 to #6 on the downstream side of the transport direction D1 used for OL printing and the nozzle range of nozzle numbers #N-5 to #N on the upstream side are referred to as the downstream nozzle range and the upstream nozzle range, respectively. Of course, there are no limitations on the number of nozzles in each of the downstream nozzle range and the upstream nozzle range.

[0038] In the first example, some of the nozzles 21 in the upstream nozzle range of nozzle row 23K, specifically the nozzles 21 with nozzle numbers #N-2 to #N, are designated as unused nozzles, and some of the nozzles 21 in the downstream nozzle range of nozzle row 23C, specifically the nozzles 21 with nozzle numbers #1 to #3, are designated as unused nozzles. Unused nozzles are nozzles 21 that are not used for printing, and in Figure 2, unused nozzles are indicated by an x ​​inside a circle representing the nozzle 21. Nozzles 21 that are not unused nozzles eject ink under the control of control unit 11.

[0039] In this configuration, attention will be focused on the ejection of K ink by nozzle array 23K. Region 41 corresponds to the "first overlap region" where each raster line is formed by two scans by nozzle array 23K. For example, one raster line that makes up first overlap region 41 is recorded in OL by nozzle 21 with nozzle number #N-5 of nozzle array 23K in pass P1 and nozzle 21 with nozzle number #1 of nozzle array 23K in pass P2. The areas of medium 40 other than region 41 correspond to the "first normal region" where each raster line is formed by one scan by nozzle array 23K.

[0040] Similarly, let's look at the ejection of C ink by nozzle array 23C. Region 42 corresponds to the "second overlap region" where each raster line is formed by two scans by nozzle array 23C. For example, one raster line that makes up second overlap region 42 is recorded in OL by nozzle 21 with nozzle number #N-2 of nozzle array 23C in pass P1 and nozzle 21 with nozzle number #4 of nozzle array 23C in pass P2. The areas of medium 40 other than region 42 correspond to the "second normal region" where each raster line is formed by one scan by nozzle array 23C. That is, the first overlapping region 41 overlaps with a part of the second normal region, and the second overlapping region 42 overlaps with a part of the first normal region.

[0041] In this way, in the first example, some nozzles 21 of the first nozzle row are designated as non-used nozzles in either the upstream nozzle range or the downstream nozzle range, and some nozzles 21 of the second nozzle row are designated as non-used nozzles in the other of the upstream nozzle range or the downstream nozzle range, thereby shifting the first overlapping region 41 recorded in OL by the first nozzle row and the second overlapping region 42 recorded in OL by the second nozzle row in the transport direction D1. In other words, the first overlapping region 41 is formed in a position overlapping with the second normal region when viewed from the longitudinal direction of the raster line. It can also be said that the second overlapping region 42 is formed in a position overlapping with the first normal region when viewed from the longitudinal direction.

[0042] Second example: FIG. 3 shows a simplified top view of the relationship between the recording head 20 and the medium 40 according to the second example. The view of FIG. 3 is the same as FIG. 2. As with the first example, the recording device 10 in the second example is a serial printer. Explanations of the second example that are common to the first example will be omitted. In the second example, the nozzle arrays 23K and 23C of the recording head 20 are offset from each other in the transport direction D1. According to FIG. 3, the nozzle 21 with nozzle number #4 in the nozzle array 23K and the nozzle 21 with nozzle number #1 in the nozzle array 23C are aligned in the transport direction D1. In other words, in the second example, the nozzle arrays 23K and 23C are offset from each other by three nozzles in the transport direction D1.

[0043] The nozzle arrays 23K and 23C shown in FIG. 3 can be considered to have a configuration similar to that of the nozzle arrays 23K and 23C shown in FIG. 2, with unused nozzles removed. Therefore, the number of nozzles N per nozzle array in the nozzle arrays 23K and 23C shown in FIG. 3 is three less than the number of nozzles N in FIG. 2. Therefore, even if the print head 20 shown in FIG. 3 is used instead of the print head 20 shown in FIG. 2, the first overlap area 41 and the first normal area can be printed on the medium 40 by the nozzle array 23K, and the second overlap area 42 and the second normal area can be printed on the medium 40 by the nozzle array 23C, just like in the first example. That is, the first overlap area 41 printed in OL by the first nozzle array and the second overlap area 42 printed in OL by the second nozzle array are printed offset from each other in the transport direction D1.

[0044] 3, the nozzle range of nozzle numbers #1 to #3 on the downstream side in the transport direction D1 used for OL recording and the nozzle range of nozzle numbers #N-2 to #N on the upstream side are referred to as the downstream nozzle range and the upstream nozzle range, respectively. Focusing on the ejection of K ink by nozzle array 23K, a given raster line constituting first overlap region 41 is OL recorded by the nozzle 21 with nozzle number #N-2 of nozzle array 23K in pass P1 and the nozzle 21 with nozzle number #1 of nozzle array 23K in pass P2. Focusing on the ejection of C ink by nozzle array 23C, a given raster line constituting second overlap region 42 is OL recorded by the nozzle 21 with nozzle number #N-2 of nozzle array 23C in pass P1 and the nozzle 21 with nozzle number #1 of nozzle array 23C in pass P2.

[0045] Example 3: 4 shows a simplified top view of the relationship between the recording head 20 and the medium 40 according to the third example. In the first and second examples, the recording device 10 is assumed to be a serial printer, but in the third example and the fourth example described below, the recording device 10 is assumed to be a so-called line printer. For the third example as well, explanations common to the first example shown in FIG. 2 will be omitted where appropriate.

[0046] In the third example, the recording unit 17 does not have a carriage, and the recording head 20 does not move. The recording head 20 is configured by connecting multiple head chips 22a, 22b, and 22c along the nozzle alignment direction D3. Also, in the third example, the transport direction D1 of the medium 40 by the transport unit 16 intersects with the nozzle alignment direction D3. The intersecting direction here may also be interpreted as being perpendicular or nearly perpendicular. In other words, the recording head 20 is configured so that the length of the recording head 20 in the nozzle alignment direction D3 can cover the width of the medium 40 in the nozzle alignment direction D3.

[0047] The number of head chips constituting print head 20 may naturally be more than the three shown in FIG. 4. Like print head 20 shown in FIG. 2, head chips 22a, 22b, and 22c each have multiple nozzle arrays. Nozzle arrays 23K and 23C of head chip 22a will be referred to as nozzle arrays 23K1 and 23C1. Similarly, nozzle arrays 23K and 23C of head chip 22b will be referred to as nozzle arrays 23K2 and 23C2, and nozzle arrays 23K and 23C of head chip 22c will be referred to as nozzle arrays 23K3 and 23C3. In FIG. 4, the multiple nozzle arrays in the head chip are aligned along transport direction D1 and are positioned at the same position in nozzle alignment direction D3.

[0048] In Figure 4, a nozzle number is assigned to each nozzle 21 that makes up a nozzle row in the head chip. For the N nozzles that make up one nozzle row in the head chip, nozzle numbers are assigned in order from one end to the other in the nozzle arrangement direction D3, such as #1, #2, #3, ... #N. In the third example, the multiple nozzle rows in the head chip are positioned in the same position in the nozzle arrangement direction D3, so the nozzle number within the head chip is information common to each nozzle row.

[0049] In the third example, the control unit 11 performs the conveyance of the medium 40 from upstream to downstream in the conveyance direction D1 by the conveyance unit 16 at a predetermined speed in parallel with the ejection of ink from the recording head 20, thereby recording an image two-dimensionally on the medium 40 based on image data representing the image. Also, in the third example, a line recorded on the medium 40 with the conveyance direction D1 as its longitudinal direction is called a "raster line." In other words, in the image data, a raster line is a pixel row in which multiple pixels are aligned in the conveyance direction D1, and on the medium 40, it is a row of dots facing the conveyance direction D1. The length of the raster line is not important.

[0050] In the third example, control unit 11 also performs OL printing on some raster lines using multiple nozzles 21. In the first and second examples, distance L1 is adjusted to overlap part of the area printed in the preceding pass with OL printing in the succeeding pass, but in the third example, due to the configuration of print head 20, the head chips partially overlap in the nozzle alignment direction D3. Specifically, in FIG. 4, the nozzle range of nozzle numbers #N-5 to #N of head chip 22a overlaps with the nozzle range of nozzle numbers #1 to #6 of head chip 22b. The nozzle ranges also overlap similarly between head chip 22b and head chip 22c.

[0051] For such a head chip, the nozzle range of nozzle numbers #1 to #6 at one end of the nozzle alignment direction D3 and the nozzle range of nozzle numbers #N-5 to #N at the other end of the nozzle alignment direction D3 can be interpreted in the same way as the downstream nozzle range and upstream nozzle range in the first example, including the presence of unused nozzles in each range.

[0052] In this configuration, attention is focused on the ejection of K ink by the groups of nozzle arrays 23K1, 23K2, and 23K3 of each head chip 22a, 22b, and 22c. Region 43 corresponds to a "first overlap region" in which each raster line is formed by ink ejection by nozzle arrays 23K1 and 23K2, or by ink ejection by nozzle arrays 23K2 and 23K3. For example, a given raster line constituting first overlap region 43 is recorded in OL by nozzle 21 with nozzle number #N-5 in nozzle array 23K1 and nozzle 21 with nozzle number #1 in nozzle array 23K2. The rest of the medium 40 corresponds to a "first normal region" in which a raster line is formed by a nozzle 21 in either nozzle array 23K1, nozzle array 23K2, or nozzle array 23K3.

[0053] Focus on the ejection of C ink by the groups of nozzle arrays 23C1, 23C2, and 23C3 of each head chip 22a, 22b, and 22c. Region 44 corresponds to a "second overlap region" where each raster line is formed by ink ejection by nozzle arrays 23C1 and 23C2 or by ink ejection by nozzle arrays 23C2 and 23C3. For example, a raster line constituting second overlap region 44 is recorded in OL by nozzle 21 with nozzle number #N-2 in nozzle array 23C1 and nozzle 21 with nozzle number #4 in nozzle array 23C2. The rest of the medium 40 corresponds to a "second normal region" where a raster line is formed by nozzle 21 of either nozzle array 23C1, nozzle array 23C2, or nozzle array 23C3. In other words, first overlap region 43 overlaps with a portion of the second normal region, and second overlap region 44 overlaps with a portion of the first normal region.

[0054] In the third example, a pair of head chips that overlap each other is focused on. For example, nozzle row 23K1 is referred to as the "first nozzle row," nozzle row 23K2 as the "second nozzle row," nozzle row 23C1 as the "third nozzle row," and nozzle row 23C2 as the "fourth nozzle row." Of course, nozzle row 23K2 may also be interpreted as the "first nozzle row," nozzle row 23K3 as the "second nozzle row," nozzle row 23C2 as the "third nozzle row," and nozzle row 23C3 as the "fourth nozzle row." In this third example, a first normal region in which raster lines are formed using either the first or second nozzle row, a first overlap region 43 in which raster lines are formed using the first and second nozzle rows, a second normal region in which raster lines are formed using either the third or fourth nozzle row, and a second overlap region 44 in which raster lines are formed using the third and fourth nozzle rows are printed. The first overlapping region 43 and the second overlapping region 44 are offset from each other in the nozzle arrangement direction D3. In other words, the first overlapping region 43 is formed at a position overlapping with the second normal region when viewed from the longitudinal direction of the raster line. It can also be said that the second overlapping region 44 is formed at a position overlapping with the first normal region when viewed from the longitudinal direction.

[0055] Example 4: FIG. 5 shows a simplified top view of the relationship between the recording head 20 and the medium 40 in the fourth example. The way to view FIG. 5 is the same as FIG. 4. As with the third example, the recording device 10 in the fourth example is a line printer. Explanations of the fourth example that are common to the third example will be omitted. The relationship between the third example and the fourth example can be understood to be the same as the relationship between the first example and the second example.

[0056] That is, in the fourth example, the positions of the multiple nozzle rows are shifted from one another in the nozzle arrangement direction D3 in each of the multiple head chips 22a, 22b, and 22c of the print head 20. The amount of shift between nozzle row 23K1 and nozzle row 23C1, the amount of shift between nozzle row 23K2 and nozzle row 23C2, and the amount of shift between nozzle row 23K3 and nozzle row 23C3 are the same as the amount of shift between nozzle row 23K and nozzle row 23C in FIG.

[0057] Each of the nozzle arrays 23K1, 23C1, 23K2, 23C2, 23K3, and 23C3 shown in FIG. 5 can be considered to have a configuration in which unused nozzles have been removed from each of the nozzle arrays 23K1, 23C1, 23K2, 23C2, 23K3, and 23C3 shown in FIG. 4. Therefore, in FIG. 5, the number of nozzles per nozzle array in the head chip is three less than the number of nozzles N in FIG. 4. Therefore, even if the print head 20 shown in FIG. 5 is used instead of the print head 20 shown in FIG. 4, the first overlap region 43 can be recorded in OL mode using the first and second nozzle arrays, the first normal region can be recorded using the first or second nozzle array, the second overlap region 44 can be recorded in OL mode using the third and fourth nozzle arrays, and the second normal region can be recorded using the third or fourth nozzle array, just like in the third example. That is, the first overlapping region 43 and the second overlapping region 44 are printed with a shift in the nozzle arrangement direction D3.

[0058] 5, when attention is paid to the ejection of K ink by the nozzle arrays 23K1 and 23K2, one raster line that constitutes the first overlap region 43 is recorded in OL by the nozzle 21 with nozzle number #N-2 of the nozzle array 23K1 and the nozzle 21 with nozzle number #1 of the nozzle array 23K2. Also, when attention is paid to the ejection of C ink by the nozzle arrays 23C1 and 23C2, one raster line that constitutes the second overlap region 44 is recorded in OL by the nozzle 21 with nozzle number #N-2 of the nozzle array 23C1 and the nozzle 21 with nozzle number #1 of the nozzle array 23C2.

[0059] 3. Pattern recording and foreign object detection explanation: Fig. 6 is a flowchart showing the flow of pattern recording and foreign object detection performed by the recording and reading system 1. Even if the recording device 10 and the reading device 30 that make up the recording and reading system 1 are separate devices, Fig. 6 simply describes the processes performed by each device 10, 30 in a single flowchart.

[0060] In step S100, the recording control unit 12a of the control unit 11 controls the recording unit 17 and the conveying unit 16 to record a "density correction pattern" and a "comparison pattern" on the medium 40 based on image data for pattern recording stored in advance in the memory unit 18, etc. The image data for pattern recording is image data representing the density correction pattern and the comparison pattern. The density correction pattern corresponds to a "first pattern" having a first overlapping area and a first normal area, and the comparison pattern corresponds to a "second pattern" having a second overlapping area and a second normal area. Step S100 is a "pattern recording process" that records a pattern on the medium 40. The comparison pattern is used to detect foreign matter in the reading unit 34, as described below.

[0061] In this embodiment, any of the first to fourth examples described above may be used as specific examples of the recording head 20, conveyance, etc. In other words, if the recording device 10 is configured to use the first or second example, in step S100, the recording control unit 12a controls the first nozzle row to record on the medium 40 a density correction pattern having a first overlapping region, which is an overlapping region in which raster lines having the main scanning direction D2 as their longitudinal direction are formed by m scans, and a first normal region, which is a normal region in which raster lines are formed by n scans, which is less than m, and controls the second nozzle row to record on the medium 40 a comparison pattern having a second overlapping region, which is the overlapping region, and a second normal region, which is the normal region. According to the explanation so far, m=2 and n=1.

[0062] Alternatively, if the recording device 10 is configured to adopt the third or fourth example, in step S100, the recording control unit 12a controls the first and second nozzle rows to record on the medium 40 a density correction pattern having a first normal region in which raster lines having a longitudinal direction in the transport direction D1 intersecting the nozzle alignment direction D3 are formed using the first or second nozzle row, and a first overlap region in which the raster lines are formed using the first and second nozzle rows, and controls the third and fourth nozzle rows to record on the medium 40 a comparison pattern having a second normal region in which raster lines are formed using the third or fourth nozzle row, and a second overlap region in which the raster lines are formed using the third and fourth nozzle rows.

[0063] According to step S100, on the medium 40, the first overlapping region in the density correction pattern is formed at a position that overlaps with the second normal region in the comparison pattern when viewed in the longitudinal direction of the raster line. In step S110, the control unit 31 controls the transport unit 33 and the reading unit 34, and causes the reading unit 34 to read the density correction pattern and the comparison pattern recorded on the medium 40 in step S100.

[0064] FIG. 7 shows a simplified top view of the medium 40 and the reading unit 34 after pattern recording in step S100. As shown in FIG. 7, multiple density correction patterns 50, 51, 52, 53, and 54 and a comparison pattern 60 are recorded on the medium 40 along direction D4. The patterns 50, 51, 52, 53, 54, and 60 do not overlap with each other in direction D4. As can be seen from the previous examples, the density correction patterns 50, 51, 52, 53, and 54 are recorded with K ink, and the comparison pattern 60 is recorded with C ink. Direction D4 is the longitudinal direction of the raster lines and, in the scenario shown in FIG. 7, is also the transport direction for transporting the medium 40 toward the reading unit 34. Note that if the third or fourth example is used as the configuration of the recording head 20 and the reading unit 34 is assembled downstream of the recording head 20 in the transport direction D1, then the transport direction D1 can be interpreted as D4. On the other hand, in a configuration that adopts the first or second example as the configuration of the recording head 20, it is necessary to automatically or manually change the orientation of the medium 40 after recording so that the longitudinal direction of the raster lines on the medium 40 after recording faces the direction D4.

[0065] The density correction patterns 50, 51, 52, 53, and 54 are each printed at a different density of K, while the comparison pattern 60 is printed at a predetermined density of C. Density can be interpreted as the dot occurrence rate per unit area or the dot coverage rate. The density correction patterns 50, 51, 52, 53, and 54 and the comparison pattern 60 are all band-shaped patterns whose longitudinal direction is direction D5, which intersects direction D4. Each pattern has a constant density. The term "constant density" here means that the density represented by the image data for pattern printing is a constant value for each pattern. However, each pattern actually printed on the medium 40 will have variations in density, i.e., uneven density, depending on factors such as variations in the ejection characteristics of each nozzle 21.

[0066] The direction D5 for the medium 40 corresponds to the nozzle arrangement direction D3 when the print head 20 prints on the medium 40. In FIG. 7, the density correction patterns 50, 51, 52, 53, and 54 are printed in order of increasing density. For example, the density correction pattern 50 is printed at 20%, the density correction pattern 51 is printed at 40%, the density correction pattern 52 is printed at 60%, the density correction pattern 53 is printed at 80%, and the density correction pattern 54 is printed at 100%, each printed at a density (constant value) determined by the image data. If a single raster line RL having a maximum length in the direction D4, as shown by the dashed line in FIG. 7, is printed on the medium 40 after such patterns have been printed, this raster line RL will include a portion of each of the density correction patterns 50, 51, 52, 53, and 54 and the comparison pattern 60.

[0067] As shown in FIG. 7, the reading unit 34 has a longitudinal direction in direction D5. In other words, the line sensor of the reading unit 34 is disposed with its longitudinal direction in direction D5. Therefore, the medium 40 after pattern recording is transported in direction D4, and the reading unit 34 reads the medium 40, thereby obtaining the densities of the density correction patterns 50, 51, 52, 53, and 54 and the comparison pattern 60 for each raster line position. Note that the information obtained by the reading unit 34 as the reading result of the medium 40 may be, for example, the luminance of each pixel, but the information obtained by the reading unit 34 as the reading result is also referred to as "density." The density correction patterns 50, 51, 52, 53, and 54 are patterns for calculating "density correction values" to correct for density variations for each raster line position. The calculation of the density correction values ​​will be described later.

[0068] 7, an enlarged view 7A shows a portion of the density correction pattern 50 and a portion of the comparison pattern 60, which are enclosed by a two-dot chain line on the medium 40. The enlarged view 7A also shows, in graph form, the reading results of the reading unit 34 for the portion of the density correction pattern 50 and the portion of the comparison pattern 60. The horizontal axis of the graph represents the density as the reading result, and the vertical axis represents the position of each raster line. The position of each raster line can also be considered the position of the nozzle 21 in the nozzle arrangement direction D3.

[0069] As shown in enlarged view 7A, the density correction pattern 50 has a first overlapping region 50a and a first normal region 50b. The comparison pattern 60 has a second overlapping region 60a and a second normal region 60b. The manner in which the first overlapping region, first normal region, second overlapping region, and second normal region are printed has been described above. As described above, the density correction pattern 50 is an image printed with K ink, for example, at a density of 20%, and the comparison pattern 60 is an image printed with C ink at a predetermined density. However, enlarged view 7A shows the shading of the density correction pattern 50 and the comparison pattern 60 for the sake of explanation, and does not necessarily correspond to the colors and densities of the original patterns 50 and 60 shown in FIG. 7.

[0070] Ideally, the density within the density correction pattern 50 would be consistent, but there is a density difference between the first overlap region 50a and the first normal region 50b. That is, the first normal region 50b, where each raster line is recorded with one nozzle 21, and the first overlap region 50a, where each raster line is recorded with two nozzles 21, have different overlap amounts between dots and different landing time differences between dots, which can easily result in density differences on the medium 40. In the example of enlarged FIG. 7A, the first overlap region 50a has a higher density, i.e., is darker, than the first normal region 50b. Similarly, ideally, the density within the comparison pattern 60 would be consistent, but there is a density difference between the second overlap region 60a and the second normal region 60b. In the example of enlarged FIG. 7A, the second overlap region 60a has a higher density than the second normal region 60b.

[0071] As is clear from enlarged view 7A, the first overlapping region 50a in the density correction pattern 50 overlaps with the second normal region 60b in the comparison pattern 60 when viewed in the longitudinal direction of the raster lines, but is misaligned with the second overlapping region 60a. In both the overlapping regions 50a, 60a and the normal regions 50b, 60b, there are subtle differences in density at each raster line position due to variations in the ejection characteristics of the nozzles 21 used to print each raster line. However, enlarged view 7A omits depiction of such subtle density differences at each raster line position, and instead clearly illustrates the density differences between the first overlapping region 50a and the first normal region 50b, and the density differences between the second overlapping region 60a and the second normal region 60b.

[0072] In step S120, the control unit 31 detects foreign matter in the reading unit 34 based on the results of reading the density correction pattern and the comparison pattern by the reading unit 34. The control unit 31 that executes step S120 corresponds to the "detection unit" that executes foreign matter detection. In this case, the control unit 31 compares the results of reading the density correction pattern with the results of reading the comparison pattern, and determines that a foreign matter is present if there is a range where the density changes significantly at the same position in both results.

[0073] Like the enlarged view 7A in Fig. 7, Fig. 8 shows a portion of the density correction pattern 50 and a portion of the comparison pattern 60, along with the respective read results by the reading unit 34. Fig. 8 differs from the enlarged view 7A in that the density of the foreign matter F adhering to the reading unit 34 is shown in the graph of the read results. Note that although the foreign matter F is adhering to the reading unit 34, the foreign matter F is depicted artificially in the density correction pattern 50 and the comparison pattern 60 because the patterns 50 and 60 appear as shown in Fig. 8 from the reading unit 34.

[0074] As described above, there is a density difference between the overlapping area and the normal area within a single pattern. Meanwhile, there is also a density difference between the density of the foreign matter F and the normal area. Therefore, when analyzing only the read results of one pattern, such as the density correction pattern 50, and finding a density different from that of the normal area, it is difficult to determine whether the density corresponds to the overlapping area or the foreign matter F. In particular, when foreign matter F is attached to a position on the reading unit 34 corresponding to the overlapping area, it is difficult to detect the foreign matter F from the read results of the density correction pattern 50. In this embodiment, the first overlapping area in the density correction pattern and the second overlapping area in the comparison pattern are printed while being shifted in the nozzle arrangement direction D3. Therefore, when comparing the read results of the density correction pattern and the read results of the comparison pattern, if there is a significant density difference at a certain position between the read results of the density correction pattern and the read results of the comparison pattern, this can be said to be a density change corresponding to the overlapping area. Conversely, if there is a large density change at a certain position between the reading result of the density correction pattern and the reading result of the comparison pattern, it can be said that this density change corresponds to a foreign substance F and not to an overlapping region.

[0075] In FIG. 8, the reference numerals 70 and 71 in the graph showing the results of reading the density correction pattern 50 indicate the range where the density changes significantly compared to the density of the normal region (hereinafter referred to as the density change range). "The density changes significantly compared to the density of the normal region" means, for example, that the absolute value of the difference from the average density of the normal region in the pattern is equal to or greater than a predetermined threshold value. Similarly, in FIG. 8, the reference numerals 72, 73, and 74 in the graph showing the results of reading the comparison pattern 60 also indicate the density change range. Each of the two graphs in enlarged view 7A also shows one density change range.

[0076] As a result, of the density change ranges 70 to 74, density change ranges 70, 71, 72, and 74 are densities corresponding to foreign matter F. In other words, density change ranges 70 and 72 are the result of the density of a certain foreign matter F appearing in both the density of the density correction pattern 50 and the density of the comparison pattern 60. Similarly, density change ranges 71 and 74 are the result of the density of another foreign matter F appearing in both the density of the density correction pattern 50 and the density of the comparison pattern 60. Foreign matter F can be various, such as paper dust or ink stains, and the color and density vary depending on the specific substance. However, FIG. 8 shows, as an example, a case where the density of foreign matter F is higher than that of the normal region. Density change range 70 is the density where foreign matter F overlaps part of the first overlap region 50a.

[0077] According to FIG. 8, it can be said that the density change range 70 in the graph representing the reading result of the density correction pattern 50 and the density change range 72 in the graph representing the reading result of the comparison pattern 60 occur at the same position on the vertical axis of the graph. Furthermore, density change range 71 and density change range 74 also occur at the same position. The definition of "same position" does not necessarily have to be a perfect match or a perfect overlap, but can also be defined as the same position including some error or margin. Thus, when a reading result such as that shown in FIG. 8 is obtained, the control unit 31 determines that foreign matter detection was successful, i.e., that a foreign matter is present. On the other hand, when a reading result such as that shown in enlarged FIG. 7A is obtained, it cannot be said that the density change range in the graph representing the reading result of the density correction pattern 50 and the density change range in the graph representing the reading result of the comparison pattern 60 occur at the same position, so the control unit 31 determines that foreign matter detection was unsuccessful, i.e., that a foreign matter is not present.

[0078] In step S130, the control unit 31 branches the process depending on the result of the foreign object detection in step S120. If the control unit 31 determines that a foreign object is present, the process proceeds from "Yes" in step S130 to step S140, whereas if the control unit 31 determines that no foreign object is present, the process proceeds from "No" in step S130 to step S150.

[0079] 7 and 8 illustrate an example in which the reading result of density correction pattern 50 is compared with the reading result of comparison pattern 60, but control unit 31 may also perform foreign substance detection by comparing the reading result of any of other density correction patterns 51, 52, 53, and 54 with the reading result of comparison pattern 60. For example, control unit 31 may use the reading result of a pattern among density correction patterns 50, 51, 52, 53, and 54 that has a density that is likely to show a density difference with a foreign substance, for comparison with the reading result of comparison pattern 60.

[0080] 4. Calculation of density correction value and explanation of correction: In step S140, the control unit 31 replaces the density of a position corresponding to the detected foreign matter in the reading results of the density correction pattern with the reading results of a nearby position in the density correction pattern. For example, as shown in FIG. 8, if the control unit 31 detects that a foreign matter is present in a density change range 71 in the reading results of the density correction pattern 50, the control unit 31 replaces the density of this density change range 71 with the density of a first normal region adjacent to or nearby the density change range 71 in step S140. Also, if the control unit 31 detects that a foreign matter is present in a density change range 70 corresponding to the first overlap region 50a in the reading results of the density correction pattern 50, the control unit 31 replaces the density of this density change range 70 with the density of another first overlap region near the density change range 70 that does not contain the density of the foreign matter.

[0081] The position of the foreign substance detected in step S120 is also common to the reading results of density correction patterns other than the density correction pattern compared with the comparison pattern 60. Therefore, if the control unit 31 detects a foreign substance by comparing the density correction pattern 50 with the comparison pattern 60 as described above, then in step S140, the control unit 31 similarly replaces the density of the position corresponding to the foreign substance in each of the reading results of the density correction patterns 51, 52, 53, and 54 with the density of a nearby position within the pattern. By performing step S140 in this manner, the influence of the foreign substance can be removed from the reading results of each of the density correction patterns 50, 51, 52, 53, and 54.

[0082] After step S130 returns "No" or step S140, in step S150, the data correction unit 12b of the control unit 11 calculates a density correction value for each raster line position. The control unit 31 transfers the read image data obtained by reading the density correction patterns 51, 52, 53, and 54 by the reading unit 34 to the control unit 11. If step S140 has been executed, the read image data transferred to the control unit 11 is naturally the data after processing in step S140.

[0083] Step S150 will be explained briefly. The data correction unit 12b calculates a density correction value for each raster line position based on the scanned image data of the density correction patterns 50, 51, 52, 53, and 54. In summary, the data correction unit 12b compares the density obtained by scanning a density correction pattern, for example, density correction pattern 50 corresponding to 20% of K, for a specific raster line position with a predetermined reference value (brightness) expected to be obtained by scanning the density correction pattern 50, and calculates a density correction value based on the comparison result. That is, if the density of the density correction pattern 50 is higher than the reference value, a density correction value that reduces (brightens) the density is calculated. Conversely, if the density of the density correction pattern 50 is lower than the reference value, a density correction value that increases (darkens) the density is calculated. A correction value that reduces the density is a correction value that acts to reduce the amount of ink, and a correction value that increases the density is a correction value that acts to increase the amount of ink.

[0084] The density correction value calculated in this manner is a correction value for correcting the density (20% of K) of the image data of the original recording medium of the density correction pattern 50, corresponding to the position of one raster line. Calculation of the density correction value according to this procedure is performed for each raster line position and for each of the original recording medium densities (20%, 40%, 60%, 80%, and 100% of K) of the density correction patterns 50 to 54. Furthermore, the data correction unit 12b performs interpolation of the density correction value as necessary, thereby obtaining density correction values ​​for each position of all raster lines and for all densities (0 to 100% of K). The data correction unit 12b stores each density correction value calculated in this manner in the memory unit 18, etc., and then ends the flowchart of FIG. 6.

[0085] Thereafter, when the control unit 11 executes image recording based on image data arbitrarily selected by the user, the data correction unit 12b corrects the K density of each pixel of the image data with a density correction value corresponding to the position and density of the raster line. Then, the recording control unit 12a controls the transport unit 16 and recording unit 17 based on the image data after this correction to record the image on the medium 40. As a result, a recording result of good image quality is obtained in which the density variations between the raster lines and the density differences between overlapping areas and normal areas are corrected.

[0086] According to the flow of steps S140 and S150 described above, and the subsequent image recording that involves correction using the density correction value, the amount of ink subsequently ejected by the nozzle 21 used to record the raster line corresponding to the position where a foreign substance was detected in step S120 is corrected by the density correction value calculated in the correction value calculation in step S150 based on the density after replacement in step S140. Therefore, when a foreign substance is detected by the detection unit, it can be said that the control unit 11 controls the ejection of liquid by the foreign substance position nozzle, which is the nozzle 21 used to record the area where the foreign substance was detected, based on the reading result by the reading unit 34 that corresponds to the nozzle 21 near the foreign substance position nozzle.

[0087] Note that density correction values ​​are required for all ink colors ejected by the print head 20. Therefore, if the print head 20 has nozzle rows for each of the CMYK inks, then in this embodiment, density correction patterns for each of the C, M, and Y inks are printed on the medium 40, similar to the K ink density correction patterns 50-54 shown in FIG. 7. The method of calculating the density correction values, including the density substitution in step S140, is the same for all ink colors. Therefore, the read results for detecting foreign matter may be compared with the read results of the comparison pattern 60 for a density correction pattern of an ink other than K. Furthermore, since the comparison pattern 60 only needs to be printed with any one color of ink, it may be printed with an ink other than C ink.

[0088] 5. Variations: If the control unit 31 determines "Yes" in step S130, it may proceed to step S160, as indicated by the dashed line in FIG. 6. In this case, steps S140 and S150 are not executed. In step S160, the control unit 31 causes the display unit 35 to display a warning indicating that there is an area that the reading unit 34 was unable to read, and then ends the flowchart in FIG. 6. The area that the reading unit 34 was unable to read is, of course, the location where a foreign object was detected. The display unit 35 may display a warning message such as, for example, "Some parts of the document could not be read due to foreign objects adhering to the image sensor." Alternatively, the display unit 35 may display a message urging the user to remove the foreign object, such as, "Foreign objects may be adhering to the image sensor. Please clean the image sensor." as one of the warning messages displayed in step S160.

[0089] Additionally, along with displaying the warning in step S160, control unit 31 may inquire of the user whether steps S140 and S150 can be executed, and if an instruction that steps S140 and S150 can be executed is received from the user, control unit 31 may proceed to steps S140 and S150.

[0090] 6. Summary: As described above, according to this embodiment, the recording device 10 includes a first nozzle row and a second nozzle row each including a plurality of nozzles 21 that eject liquid onto the medium 40, and a control unit 11 that controls the ejection of liquid by the first nozzle row and the second nozzle row. The control unit 11 can cause the first nozzle row and the second nozzle row to perform scans that eject liquid while moving forward or backward along a predetermined main scanning direction D2. The control unit 11 controls the first nozzle row to record a first pattern on the medium 40, the first pattern having a first overlapping region that is an overlapping region in which raster lines having the main scanning direction D2 as their longitudinal direction are formed by m scans, and a first normal region that is a normal region in which the raster lines are formed by n scans, where n is less than m. The control unit 11 controls the second nozzle row to form the first overlapping region at a position that overlaps with the second normal region when viewed from the longitudinal direction, when recording a second pattern on the medium 40, the second overlapping region being the overlapping region and the second normal region being the normal region.

[0091] Furthermore, according to this embodiment, the recording device 10 includes a first nozzle row, a second nozzle row, a third nozzle row, and a fourth nozzle row, which are nozzle rows in which a plurality of nozzles 21 that eject liquid onto the medium 40 are arranged in the nozzle arrangement direction D3, and a control unit 11 that can control the ejection of liquid by the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row. Then, by controlling the first nozzle row and the second nozzle row, the control unit 11 records on the medium 40 a first pattern having a first normal region in which raster lines, whose longitudinal direction is a direction intersecting the nozzle arrangement direction D3, are formed using the first nozzle row or the second nozzle row, and a first overlap region in which the raster lines are formed using the first nozzle row and the second nozzle row, and by controlling the third nozzle row and the fourth nozzle row, when recording on the medium 40 a second pattern having a second normal region in which raster lines are formed using the third nozzle row or the fourth nozzle row, and a second overlap region in which the raster lines are formed using the third nozzle row and the fourth nozzle row, the control unit 11 forms the first overlap region at a position that overlaps with the second normal region when viewed from the longitudinal direction.

[0092] With either of these configurations, when the first and second patterns are recorded on the medium 40, the first overlapping area is formed at a position that overlaps with the second normal area when viewed from the longitudinal direction of the raster lines. This allows for a pattern to be recorded that makes it easy to determine whether areas with large density variations in the read results are due to the overlapping area or foreign matter, which is useful for detecting foreign matter. Furthermore, because this type of pattern design makes foreign matter detection easier, there is no need to provide two image reading sensors to detect and clean foreign matter, as in the past, which helps reduce product costs.

[0093] Furthermore, according to this embodiment, the control unit 11 records a plurality of first patterns having different densities along the longitudinal direction. By recording a plurality of first patterns with different densities, it is possible to obtain appropriate density correction values ​​with improved density correction accuracy based on the results of reading each first pattern. However, only one first pattern may be recorded. For example, in Fig. 7, only density correction pattern 52 is recorded on medium 40 as the first pattern. The control unit compares the read results of density correction pattern 52 with the read results of comparison pattern 60 to detect foreign matter, and can also determine the density correction value for each raster line position based on the read results of density correction pattern 52.

[0094] Furthermore, according to this embodiment, the first pattern and the second pattern are printed with liquids of different colors. According to the above configuration, the first pattern and the second pattern have different colors on the medium 40, so that it is easy to distinguish the density of the first pattern from the density of the second pattern from the reading results of the medium 40, and it becomes easier to detect foreign objects based on a comparison between the first pattern and the second pattern. However, if the print head 20 has multiple rows or groups of nozzle rows that eject ink of the same color, it is also possible to print the first pattern and the second pattern with ink of the same color.

[0095] Furthermore, according to this embodiment, the recording and reading system 1 includes a recording device 10, a reading unit 34 that reads the first and second patterns recorded on the medium 40 by the recording device 10, and a detection unit (control unit 31) that detects foreign matter in the reading unit 34 based on the results of reading the first and second patterns by the reading unit 34. According to the above configuration, the record reading system 1 can detect foreign matter in the reading unit 34 based on the results of reading the first pattern and the second pattern by the reading unit 34.

[0096] Furthermore, according to this embodiment, the recording and reading system 1 is provided with a display unit 35 capable of displaying information, and when a foreign object is detected by the detection unit, the display unit 35 may display that there is an area that could not be read by the reading unit 34. According to the above configuration, when a foreign object is detected by the detection unit, the user can be made aware that there is an area that the reading unit 34 was unable to read.

[0097] Furthermore, according to this embodiment, when a foreign object is detected by the detection unit, the control unit 11 may control the ejection of liquid from the foreign object position nozzle, which is the nozzle 21 used to record the area where the foreign object was detected, based on the reading result by the reading unit 34 corresponding to the nozzle 21 in the vicinity of the foreign object position nozzle. According to the above configuration, when a foreign object is detected by the detection unit, the subsequent ejection of liquid from the nozzles 21 can be appropriately controlled based on the reading result by the reading unit 34 from which the influence of the foreign object has been eliminated.

[0098] Furthermore, this embodiment is not limited to devices and systems, but also discloses inventions in various categories, such as methods executed by devices and systems, and programs 12 that cause a processor to execute the methods. For example, a recording method by recording device 10 that performs recording by controlling the ejection of liquid from a first nozzle row and a second nozzle row consisting of a plurality of nozzles 21 that eject liquid onto medium 40 includes a pattern recording step of causing the first nozzle row and the second nozzle row to perform scans ejecting liquid while moving forward or backward along a predetermined main scanning direction D2 to record a pattern on medium 40. In the pattern recording step, the first nozzle row is controlled to record on medium 40 a first pattern having a first overlapping region that is an overlapping region in which raster lines with the main scanning direction D2 as the longitudinal direction are formed by m scans, and a first normal region that is a normal region in which raster lines are formed by n scans, which is less than m, and the second nozzle row is controlled to form the first overlapping region at a position that overlaps with the second normal region when viewed from the longitudinal direction, when a second pattern having a second overlapping region that is the overlapping region and a second normal region that is the normal region is recorded on medium 40.

[0099] In the above explanation, m = 2 and n = 1, but the values ​​of m and n may be other than these. For example, the recording device 10 may perform OL recording of each raster line in the first overlapping region with four scans of the first nozzle array, and OL recording of each raster line in the first normal region with two scans of the first nozzle array for the first pattern, and OL recording of each raster line in the second overlapping region with four scans of the second nozzle array, and OL recording of each raster line in the second normal region with two scans of the second nozzle array for the second pattern. In other words, it is sufficient that the relationship m>n holds.

[0100] In addition, the recording method by the recording device 10, which performs recording by controlling the ejection of liquid from the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row, which are nozzle rows in which a plurality of nozzles 21 that eject liquid onto the medium 40 are arranged in the nozzle arrangement direction D3, includes a pattern recording process in which the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row are made to eject liquid to record a pattern on the medium 40. In the pattern recording process, by controlling the first nozzle row and the second nozzle row, a first pattern having a first normal region in which raster lines having a longitudinal direction intersecting the nozzle arrangement direction D3 are formed using the first nozzle row or the second nozzle row, and a first overlap region in which the raster lines are formed using the first nozzle row and the second nozzle row, is recorded on the medium 40; and by controlling the third nozzle row and the fourth nozzle row, a second pattern having a second normal region in which raster lines are formed using the third nozzle row or the fourth nozzle row, and a second overlap region in which the raster lines are formed using the third nozzle row and the fourth nozzle row is recorded on the medium 40, so that the first overlap region is formed at a position overlapping with the second normal region when viewed from the longitudinal direction. [Explanation of symbols]

[0101] 1...recording and reading system, 10...recording device, 11...control unit, 12...program, 12a...recording control unit, 12b...data correction unit, 13...display unit, 16...transport unit, 17...recording unit, 18...memory unit, 20...recording head, 21...nozzle, 22a, 22b, 22c...head chip, 23C, 23K, 23C1, 23K1, 23C2, 23K2, 23C3, 23K3...nozzle array, 30... Reading device, 31...controller, 33...conveyor, 34...reader, 35...display, 40...medium, 41, 43...first overlapping area, 42, 44...second overlapping area, 50, 51, 52, 53, 54...density correction patterns, 50a...first overlapping area, 50b...first normal area, 60...comparison pattern, 60a...second overlapping area, 60b...second normal area, 70, 71, 72, 73, 74...density change range

Claims

1. a first nozzle row and a second nozzle row each consisting of a plurality of nozzles that eject a liquid onto a medium; a control unit that controls the ejection of the liquid from the first nozzle row and the second nozzle row; Equipped with The control unit controls the first nozzle row and the second nozzle row to move forward and backward along a predetermined main scanning direction. The liquid can be ejected while moving in a forward or backward direction, The control unit By controlling the first nozzle row, a raster image is formed with the main scanning direction as its longitudinal direction. a first overlapping area in which a line is formed by m scans; a first normal area, which is a normal area formed by n scans, which is less than m scans; recording a first pattern on the medium, the first pattern having: By controlling the second nozzle row, a second overlap region that is the overlap region and the and a second normal area that is a normal area, when a second pattern having the second normal area is recorded on the medium, The first overlapping region is formed at a position overlapping with the second normal region when viewed in the longitudinal direction. a recording device; The first pattern and the second pattern recorded on the medium by the recording device a reading unit that performs reading; Based on the results of reading the first pattern and the second pattern by the reading unit, a reading device including a detection unit that detects foreign matter in the reading unit; A record reading system comprising:

2. a nozzle row in which a plurality of nozzles that eject liquid onto a medium are aligned in an alignment direction of the nozzles; a first nozzle row, a second nozzle row, a third nozzle row, and a fourth nozzle row; The first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row a control unit capable of controlling the ejection of the liquid, The control unit By controlling the first nozzle row and the second nozzle row, the nozzle arrangement The raster line having a longitudinal direction intersecting the direction of the first nozzle row or the second nozzle row is a first normal region formed by using a nozzle array, and the raster line is formed by the first nozzle array and and a first overlapping region formed by using the second nozzle row. Record it on the media, By controlling the third nozzle row and the fourth nozzle row, the raster line a second normal region in which the ink droplets are formed using the third nozzle row or the fourth nozzle row; a second overlapping raster line formed using the third nozzle row and the fourth nozzle row; and a second pattern having a region on the medium, The first overlapping region is formed at a position overlapping with the second normal region when viewed in the longitudinal direction. a recording device; The first pattern and the second pattern recorded on the medium by the recording device a reading unit that performs reading; Based on the results of reading the first pattern and the second pattern by the reading unit, a reading device including a detection unit that detects foreign matter in the reading unit; A record reading system comprising:

3. The control unit arranges the plurality of first patterns having different densities along the longitudinal direction.

3. The recording and reading system according to claim 1, wherein the recording and reading system records the information.

4. The first pattern and the second pattern are recorded with liquids of different colors.

4. The recording and reading system according to claim 1, wherein:

5. A display unit capable of displaying information is provided, The display unit displays the reading information of the reading unit when the foreign object is detected by the detection unit.

5. The recording method according to claim 4, wherein a message is displayed indicating that there is an area that could not be removed. Reading system.

6. When the foreign object is detected by the detection unit, the control unit The ejection of the liquid from the foreign substance position nozzle, which is the nozzle used for recording the area, is performed Control is performed based on the reading result by the reading unit corresponding to the nozzle in the vicinity of the position nozzle.

6. The recording and reading system according to claim 1, wherein:

7. A first nozzle row and a second nozzle row each including a plurality of nozzles for ejecting a liquid onto a medium. A recording method using a recording apparatus that performs recording by controlling the ejection of the liquid, The first nozzle row and the second nozzle row are caused to perform a forward or backward movement along a predetermined main scanning direction. A pattern is recorded on the medium by scanning the liquid while moving. A recording step is included, In the pattern recording step, By controlling the first nozzle row, a raster image is formed with the main scanning direction as its longitudinal direction. a first overlapping area in which a line is formed by m scans; a first normal area, which is a normal area formed by n scans, which is less than m scans; recording a first pattern on the medium, the first pattern having: By controlling the second nozzle row, a second overlap region that is the overlap region and the and a second normal area that is a normal area, when a second pattern having the second normal area is recorded on the medium, The first overlapping region is formed at a position overlapping with the second normal region when viewed in the longitudinal direction. A recording method, and a reading unit that reads the pattern recorded on the medium by the recording device; a detection unit that detects foreign matter in the reading unit based on the pattern reading result by the reading unit; A method for detecting foreign matter using a reading device including: The first pattern and the second pattern recorded on the medium in the pattern recording step a reading step of reading the Based on the results of reading the first pattern and the second pattern in the reading step, a detection step of detecting foreign matter in a reading unit of a recording device; A recording method and a foreign matter detection method for a recording / reading system, comprising:

8. a nozzle row in which a plurality of nozzles that eject liquid onto a medium are aligned in an alignment direction of the nozzles; The liquid is ejected from the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row. A recording method using a recording device that controls and records, In front of the first nozzle row, the second nozzle row, the third nozzle row, and the fourth nozzle row a pattern recording step of recording a pattern on the medium by ejecting the liquid; In the pattern recording step, By controlling the first nozzle row and the second nozzle row, the nozzle arrangement The raster line having a longitudinal direction intersecting the direction of the first nozzle row or the second nozzle row is a first normal region formed by using a nozzle array, and the raster line is formed by the first nozzle array and and a first overlapping region formed by using the second nozzle row. Record it on the media, By controlling the third nozzle row and the fourth nozzle row, the raster line a second normal region in which the ink droplets are formed using the third nozzle row or the fourth nozzle row; a second overlapping raster line formed using the third nozzle row and the fourth nozzle row; and a second pattern having a region on the medium, The first overlapping region is formed at a position overlapping with the second normal region when viewed in the longitudinal direction. A recording method, and a reading unit that reads the pattern recorded on the medium by the recording device; a detection unit that detects foreign matter in the reading unit based on the pattern reading result by the reading unit; A method for detecting foreign matter using a reading device including: The first pattern and the second pattern recorded on the medium in the pattern recording step a reading step of reading the Based on the results of reading the first pattern and the second pattern in the reading step, a detection step of detecting foreign matter in a reading unit of a recording device; A recording method and a foreign matter detection method for a recording / reading system, comprising:

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