Printing apparatus and printing method

Abstract

To solve the problem in which: it is difficult to use a print result as a merchandise due to printing of a mark on a medium.SOLUTION: A printer includes: a first printing section which has a plurality of nozzles for discharging ink to a medium; a second printing section which can perform printing on the medium using special liquid; a defective nozzle detection section which can detect a defective nozzle by making the plurality of nozzles as objects, and a control section which controls the first printing section and the second printing section. The special liquid is liquid which becomes invisible according to lapsed time after the printing on the medium or an environment in which a printing result of the medium is visually recognized. The control section prints a special mark using the special liquid by the second printing section on a first frame which is printed by discharge of the ink in a state that the defective nozzle is included in the first printing section or a second frame which becomes a printing object by the first printing section succeeding to the first frame, of frames as printing unit regions in the medium.SELECTED DRAWING: Figure 3

Description

Technical Field

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

Background Art

[0002] In a printing apparatus that performs printing on a medium such as paper by ejecting ink from nozzles, in printing, when a defective nozzle is detected, a print or mark that can determine that the defective nozzle has occurred is printed on the medium together with the image to be printed, so that the quality of the printed result can be judged later.

[0003] Also, a label production apparatus is disclosed that includes a printing unit that prints a plurality of label images and position marks on a printing medium, an inspection unit that inspects the quality of each label image printed on the printing medium, a post-processing unit that performs post-processing on the label images printed on the printing medium based on the position marks, and a position mark changing unit that changes the state of the position marks printed on the printing medium. When the inspection unit determines that there is an abnormality in the label image, the position mark changing unit changes the position mark corresponding to the label image with the abnormality. (See Patent Document 1).

Prior Art Documents

Patent Documents

[0006] The printing apparatus comprises a first printing unit having a plurality of nozzles for ejecting ink onto a medium, a second printing unit capable of printing onto the medium using a special liquid, a defective nozzle detection unit capable of detecting defective nozzles among the plurality of nozzles, and a control unit for controlling the first printing unit and the second printing unit. The control unit completes printing by executing N passes for a single frame, which is a printing unit area on the medium, and repeats the printing for each frame for multiple frames, and causes the defective nozzle detection unit to execute a process to detect the defective nozzle after each pass is completed. The special liquid is a liquid that becomes invisible depending on the time elapsed since printing on the medium or the environment in which the printed result of the medium is visible, and the control unit, The plurality of The second printing unit prints a specific mark using the special liquid on either the first frame, which has been printed by the ejection of the ink while the first printing unit contains the defective nozzle, or on the second frame, which is the next frame to be printed by the first printing unit after the first frame.

[0007] The printing method is: A printing method using a printing apparatus comprising a first printing unit having multiple nozzles for ejecting ink onto a medium. the law of nature The printing apparatus has a second printing unit capable of printing onto the medium using a special liquid, the special liquid being a liquid that becomes invisible depending on the time elapsed since printing onto the medium or the environment in which the printing result of the medium is visible. The aforementioned printing method isA first printing step in which the first printing unit ejects the ink and prints onto a frame which is a printing unit area on the medium; a defective nozzle detection step in which a defective nozzle is detected from among a plurality of nozzles; and a second printing step in which the second printing unit prints a specific mark using the special liquid on the first frame which has been printed by the ejection of the ink while the first printing unit contains the defective nozzle, or on the second frame which is the next target of printing by the first printing unit after the first frame. The first printing step includes completing printing by performing N passes for a single frame, and repeating the printing for each frame for multiple frames; the defective nozzle detection step includes performing a process to detect the defective nozzle after each pass is completed; and the second printing step includes printing the specific mark on the first or second frame of the multiple frames using the special liquid by the second printing unit, so as to determine whether a new defective nozzle is detected after the N-1 passes are completed or after the Nth pass is completed. . [Brief explanation of the drawing]

[0008] [Figure 1] A block diagram showing a simplified configuration of the apparatus in this embodiment. [Figure 2] A simplified diagram showing the relationship between the media and the print head from a top-down perspective. [Figure 3] A flowchart illustrating part of the print control process. [Figure 4] A flowchart illustrating another part of the print control process. [Figure 5] A diagram illustrating a specific example of the first embodiment. [Figure 6] A diagram illustrating another specific example of the first embodiment. [Figure 7] A diagram illustrating a specific example of the third embodiment. [Figure 8] A diagram illustrating a specific example of the fourth embodiment. [Figure 9] A diagram illustrating a specific example of the fifth embodiment. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the figures. Note that the figures are merely illustrative examples for illustrating these embodiments. Because the figures are illustrative, the proportions, shapes, and shading may not be accurate, they may not be consistent with each other, and some parts may be omitted.

[0010] 1. Outline of the device configuration: Figure 1 shows a simplified configuration of the printing apparatus 10 according to this embodiment. The printing method of this embodiment is performed by the printing apparatus 10. The printing apparatus 10 includes a control unit 11, a display unit 13, an operation reception unit 14, a storage unit 15, a communication IF 16, a transport unit 17, a carriage 18, a print head 19, a defective nozzle detection unit 20, etc. IF stands for interface. The control unit 11 is composed of one or more ICs having a CPU 11a as a processor, ROM 11b, RAM 11c, etc., and other non-volatile memory, etc.

[0011] In the control unit 11, the processor, i.e., the CPU 11a, performs calculations according to the program 12 stored in the ROM 11b or other memory, using the RAM 11c or the like as a work area, thereby realizing various functions such as the print data generation unit 12a, the nozzle determination unit 12b, and the print control unit 12c. The processor is not limited to a single CPU; it may be configured to perform processing using multiple CPUs or hardware circuits such as ASICs, or it may be configured so that the CPU and hardware circuits cooperate in performing processing.

[0012] The display unit 13 is a means for displaying visual information and is composed of, for example, a liquid crystal display or an organic EL display. The display unit 13 may also include a display and a drive circuit for driving the display. The operation reception unit 14 is a means for receiving input from the user and is implemented by, for example, physical buttons, a touch panel, a mouse, or a keyboard. Of course, a touch panel may be implemented as a function of the display unit 13. The display unit 13 and the operation reception unit 14 together may be called the operation panel of the printing device 10. The display unit 13 and the operation reception unit 14 may be part of the configuration of the printing device 10, but they may also be peripheral devices attached to the printing device 10 externally.

[0013] The storage unit 15 is, for example, a storage means using a hard disk drive, a solid state drive, or other memories. A part of the memory possessed by the control unit 11 may be regarded as the storage unit 15. The storage unit 15 may be regarded as a part of the control unit 11. Information regarding defective nozzles is stored in the storage unit 15 in the present embodiment.

[0014] The communication IF 16 is a general term for one or more IFs for the printing apparatus 10 to communicate with an external device by wire or wirelessly in accordance with a predetermined communication protocol including a known communication standard. The external device is, for example, a communication device such as a personal computer, a server, a smartphone, or a tablet terminal.

[0015] The conveyance unit 17 is a means for conveying the medium 30 along a predetermined conveyance direction under the control of the control unit 11. The conveyance unit 17 includes, for example, rollers that rotate to convey the medium 30, a motor as a power source for rotation, and the like. Further, the conveyance unit 17 may be a mechanism that mounts the medium 30 on a belt or a pallet that moves by a motor and conveys the medium 30. The medium 30 is, for example, paper, but may be any medium that can be a target for liquid printing, and may be a material other than paper such as a film or a fabric. Of course, the medium 30 may be a label paper composed of a base material and a label that is detachably attached to the base material.

[0016] The carriage 18 is a means for reciprocating along a predetermined direction by the power of a carriage motor (not shown) under the control of the control unit 11. The carriage 18 mounts the print head 19. Accordingly, the print head 19 moves together with the carriage 18. The print head 19 is a means for performing printing by ejecting a liquid from the nozzle 21 onto the medium 30 by an inkjet method under the control of the control unit 11. The liquid is mainly ink for coloring, but in the present embodiment, the print head 19 can also eject a "special liquid". The droplets ejected from the nozzle 21 are called dots.

[0017] The special liquid is a liquid that becomes invisible depending on the time elapsed since printing on the medium 30 or the environment in which the printed result of the medium 30 is visible. As a specific example, the special liquid is a UV (Ultra Violet) emitting ink that is transparent and emits visible light when irradiated with ultraviolet light. UV emitting ink is invisible unless irradiated with ultraviolet light, such as a so-called black light, and can therefore be said to be one of the liquids that becomes invisible depending on the environment in which the printed result of the medium 30 is visible.

[0018] The special liquid may be an ink that disappears and becomes invisible after a certain amount of time has passed since printing. Alternatively, the special liquid may be an ink that disappears and becomes invisible when heat above a certain temperature is applied after printing. Special liquids that become invisible depending on the environment, such as the presence or absence of ultraviolet irradiation or heating, and the amount of time elapsed are known. In the following, when the term "ink" is used, unless otherwise specified, it refers to the ink used to color the medium 30 with colorants, and does not refer to the special liquid. The following explanation will continue assuming that the special liquid is UV-emitting ink.

[0019] The defective nozzle detection unit 20 is a means capable of performing a defective nozzle detection process to detect "defective nozzles" among a plurality of nozzles 21 for ejecting ink from the print head 19. In the field of printing equipment, it is known that thickening of ink, mixing of air bubbles, and adhesion of paper dust and dirt in the nozzle or the internal space communicating with the nozzle can cause clogging of the nozzle, resulting in poor ink ejection. A nozzle that ejects poorly compared to a nozzle that ejects normally is called a defective nozzle. A defective nozzle may also be called an abnormal nozzle. A defective nozzle causes a condition in which ink dots that should be ejected onto the medium 30 are not ejected, so-called dot missing.

[0020] Various methods, including known methods, can be used for the defective nozzle detection process, and are not particularly limited. For example, the print head 19 is moved by the carriage 18 to a predetermined inspection position away from the medium 30, and ink is ejected from each nozzle 21. A light sensor, which serves as the defective nozzle detection unit 20, detects whether or not a dot was actually ejected from each nozzle 21. This allows the nozzle 21 from which no dot was ejected to be detected as a defective nozzle.

[0021] Furthermore, the defective nozzle detection unit 20 can also detect defective nozzles based on residual vibrations by applying a predetermined drive signal to the actuator of the nozzle 21 to generate residual vibrations in the pressure chamber. In the print head 19, each nozzle 21 is provided with an actuator made of a piezoelectric element and a pressure chamber that is deformed by the actuator to eject ink from the nozzle 21. Although details are omitted, the print head 19 outputs a drive signal to the actuator of the nozzle 21 to generate residual vibrations in the pressure chamber that are not sufficient to eject ink from the nozzle 21 for inspection purposes. The defective nozzle detection unit 20 detects the residual vibrations after the pressure change in the pressure chamber caused by this drive signal as a change in the electromotive force of the piezoelectric element constituting the actuator. The defective nozzle detection unit 20 then determines whether the nozzle 21 to be inspected is a normal nozzle or a defective nozzle by comparing the state of these residual vibrations, such as frequency, period, amplitude, etc., with a preset reference value for determining whether it is normal or defective.

[0022] The printing apparatus 10 may be implemented by a single printer, but it may also be implemented by a system having multiple devices connected in a communicative manner. For example, the printing apparatus 10 may be a system that includes an information processing device that plays the role of a control unit 11, and a printer that performs printing under the control of the information processing device, including a transport unit 17, a carriage 18, a print head 19, and a defective nozzle detection unit 20. In this case, the information processing device can be understood as a print control device, an image processing device, or the like.

[0023] Figure 2 shows a simplified view from above of the relationship between the media 30 and the print head 19, etc. In Figure 2, two orthogonal directions D1 and D2 are shown. Direction D1 will be called the conveying direction D1 of the media 30 by the conveying unit 17, and direction D2 will be called the width direction D2. The upstream and downstream of the conveying direction D1 will also be simply called upstream and downstream. In the example in Figure 2, the media 30 is conveyed from upstream to downstream on the platen 23 by the conveying unit 17. The platen 23 is a stand that supports the media 30 and can be said to be part of the conveying path of the media 30.

[0024] In Figure 2, each circle represents an individual nozzle 21. The print head 19 prints an image onto the medium 30 by ejecting or not ejecting ink dots from each nozzle 21 based on print data for printing the image generated by the control unit 11. The print head 19 can select whether to eject (dot on) or not eject (dot off) a dot for each nozzle 21 by controlling the application of a drive signal to the actuator for each nozzle 21 based on the print data. The print head 19 can eject various color inks such as cyan (C), magenta (M), yellow (Y), and black (K), as well as special liquids.

[0025] The print head 19 is equipped with nozzle groups 22 for different types of liquids. Figure 2 shows an example of the arrangement of nozzles 21 in the print head 19. Nozzle group 22C consists of multiple nozzles 21 that eject C ink. Similarly, nozzle group 22M consists of multiple nozzles 21 that eject M ink, nozzle group 22Y consists of multiple nozzles 21 that eject Y ink, and nozzle group 22K consists of multiple nozzles 21 that eject K ink. In addition, nozzle group 22S consists of multiple nozzles 21 that eject special liquids. Of the print head 19, nozzle groups 22C, 22M, 22Y, and 22K correspond to specific examples of the "first printing section" which has multiple nozzles 21 that eject ink onto the medium 30. On the other hand, nozzle group 22S of the print head 19 corresponds to a specific example of the "second printing section" which is capable of printing onto the medium 30 using a special liquid. In the example shown in Figure 2, the second printing section is located downstream of the first printing section.

[0026] In the example in Figure 2, each nozzle group 22 is formed by a plurality of nozzles 21 arranged over a range that can cover the medium width, which is the length of the medium 30 in the width direction D2. The plurality of nozzle groups 22C, 22M, 22Y, 22K, and 22S are arranged at the same position in the width direction D2 and are aligned along the transport direction D1. One nozzle group 22 is formed by a plurality of nozzles 21 arranged in a row, where the nozzle pitch, which is the distance between the nozzles 21 in the width direction D2, is constant or approximately constant. In Figure 2, for simplicity, one nozzle group 22 is shown as one nozzle row, where a plurality of nozzles 21 are arranged along the width direction D2. Of course, one nozzle group 22 may be formed by multiple nozzle rows, and the direction in which the nozzles 21 forming the nozzle group 22 are arranged may be oblique to the width direction D2. Also, regardless of the arrangement of the nozzles 21 forming the nozzle group 22, the nozzle group 22 may be referred to as a nozzle row 22.

[0027] In the example shown in Figure 2, the carriage 18 is capable of reciprocating parallel to the transport direction D1 at a predetermined height above the platen 23. The control unit 11 moves the carriage 18 back and forth parallel to the transport direction D1 while the medium 30 is stationary on the platen 23, and ejects ink from each nozzle group 22C, 22M, 22Y, and 22K of the print head 19 during the movement of the carriage 18. The ink ejection by the print head 19 based on the print data accompanying the movement of the carriage 18 is called a "pass". If the movement of the carriage 18 from upstream to downstream is called the forward movement, and the movement of the carriage 18 from downstream to upstream is called the return movement, then the ink ejection accompanying the forward movement is the forward pass, and the ink ejection accompanying the return movement is the return pass. Printing performed in both the forward and return passes is called bidirectional printing, and printing performed in only one of the forward or return passes is called unidirectional printing. In this embodiment, either bidirectional or unidirectional printing is acceptable.

[0028] The control unit 11 controls the carriage 18 and print head 19 to execute one or more passes while the medium 30 is stationary on the platen 23, thereby printing on "frames," which are printing unit areas on the medium 30. A frame is an area of ​​a predetermined size. After printing on one frame is completed, the control unit 11 has the transport unit 17 transport the medium a distance equivalent to one frame, and then prints on the next frame. By repeating this process, the control unit 11 can continuously print on multiple frames of the medium 30.

[0029] As will be described later, nozzle group 22S is used to print a "specific mark" indicating that printing was performed by ejecting ink while a defective nozzle was present in the first printing section. The specific mark may be called by any name, but hereafter it will be called an "index". In the example in Figure 2, nozzle group 22S as the second printing section has a length in the width direction D2 that can cover the width of the media, similar to nozzle groups 22C, 22M, 22Y, and 22K corresponding to the ink. However, since nozzle group 22S only needs to be a means capable of printing the index with a special liquid, it does not need to have the same length or number of nozzles in the width direction D2 as nozzle group 22 corresponding to the ink.

[0030] The carriage 18 may be configured to move in a direction parallel to the transport direction D1 and in a direction parallel to the width direction D2. In other words, the control unit 11 may change the position of the carriage 18 and the media 30 in the width direction D2 for each pass during printing of one frame. Alternatively, the transport direction of the medium 30 by the transport unit 17 may be set to be parallel to the direction D2 in Figure 2, and the control unit 11 may perform printing by alternately repeating the transport of the medium 30 and the movement of the print head 19 parallel to the direction D1 by the carriage 18.

[0031] Alternatively, the printing apparatus 10 may have a configuration without a carriage 18. In other words, in the configuration of Figure 2, the carriage 18 may be omitted and the print head 19 may be fixed above the platen 23, and printing may be performed by ink ejected from the print head 19 as the medium 30, which is transported along the transport direction D1 by the transport unit 17, passes downstream below the print head 19. This configuration in which the print head 19 does not move can be understood as substantially the same as a configuration in which one frame is printed in one pass.

[0032] 2. First Embodiment: A first embodiment will be described. Figure 3 shows a flowchart of part of the print control process executed by the control unit 11 according to program 12. Note that the execution order of each step in the flowchart does not have to be limited to the order shown in the figure. Also, the division of roles of each functional unit within the control unit 11, such as the print data generation unit 12a, nozzle determination unit 12b, and print control unit 12c, does not have to be interpreted restrictively as in the example described below. The control unit 11 completes printing by executing N passes for one frame of the medium 30, and repeats this frame-by-frame printing for multiple frames. N is an integer of 1 or more. Here, as an example, let's assume N=4. The flowchart in Figure 3 is a process targeting a single frame, and the frame currently being targeted will be called the "target frame".

[0033] In step S100, the print data generation unit 12a of the control unit 11 generates print data necessary for executing a path to the target frame. Here, it is assumed that the image data that will be the source of the print data, which represents an image desired by the user, has been specified, for example, through an operation by the user on the operation reception unit 14, and that the print data generation unit 12a has already acquired this image data from an image data storage location such as the storage unit 15 or memory inside or outside the printing device 10. Alternatively, it is assumed that the print data generation unit 12a has received and acquired image data transmitted from an external device via the communication IF 16.

[0034] The print data generation unit 12a performs various processes on the image data as needed, such as resolution conversion, color conversion, and halftone processing, to generate print data for one frame. The print data is data that defines dot-on or dot-off for each pixel and each CMYK ink. As is known, the control unit 11 can eject dots of different sizes from the nozzles 21 by varying the waveform of the drive signal applied to the actuator of each nozzle 21 of the print head 19. For example, the nozzles 21 can eject dots of three sizes called large dots, medium dots, and small dots. The size of a dot can be the amount of ink per dot or the diameter of the dot. Naturally, large dot > medium dot > small dot holds true. In this example, the ink dot-on information in the print data further indicates whether it is large dot-on, medium dot-on, or small dot-on.

[0035] As described above, if N=4, the print data generation unit 12a decomposes the print data for one frame, associating it with each of the four passes. In other words, each pixel constituting the print data for one frame is associated with one of the first to fourth passes. As a result, print data for one frame is generated, with print data for each of the four passes to be used. Here, we assume that each raster line constituting one frame is printed in N passes. A raster line is a line oriented in a direction that intersects the direction in which the nozzles 21 are arranged, and in the example in Figure 2, it is a sequence of pixels arranged along the transport direction D1 that intersects the width direction D2. In other words, each raster line within one frame is printed in N passes. The print result on the medium 30 of such a sequence of pixels can also be called a raster line.

[0036] In the example in Figure 2, if the carriage 18 only moves back and forth parallel to the transport direction D1, then one color of ink for one raster line is printed by one nozzle 21 that ejects that single color of ink. On the other hand, in the example in Figure 2, if the carriage 18 can move back and forth parallel to the width direction D2 in addition to the transport direction D1, and the positions of the medium 30 and the print head 19 in the width direction D2 differ for each pass, then one color of ink for one raster line is printed by multiple nozzles 21 that eject that single color of ink.

[0037] Figure 5 is a diagram illustrating a specific example of the first embodiment, showing the medium 30, print head 19, etc., from the same viewpoint as in Figure 2. In Figure 5, the carriage 18 and print head 19 are shown as a single unit, and the platen 23 is omitted. Also, the nozzle groups 22C, 22M, 22Y, and 22K corresponding to the first printing section are shown together as the first printing section 24, and the nozzle group 22S is shown as the second printing section 25.

[0038] In the example in Figure 5, the medium 30 is a long roll of paper in the transport direction D1, and the medium 30 is divided into multiple frames 301, 302, 303, 304… in the transport direction D1. Each frame 301, 302, 303, 304… may or may not be visually distinguishable to the user. In the upper part of Figure 5, an image 31 has already been printed on frame 301, which is adjacent to frame 302 downstream, in N passes based on print data. Therefore, the upper part of Figure 5 can be said to show the scene where frame 302 becomes the target frame and the flowchart in Figure 3 begins. In the scenes shown in the upper and lower parts of Figure 5, the transport of the medium 30 is stopped.

[0039] In Figure 5, the movable range of the carriage 18 parallel to the transport direction D1 is shown as the movement range W1. The movement range W1 is approximately equivalent to one frame. In other words, in the example in Figure 5, the movement range W1 is substantially limited to the target frame, and the print head 19 cannot print on frames other than the target frame. Also in the example in Figure 5, the irradiation unit 26 is positioned at a predetermined location on the transport path of the medium 30, downstream and spaced apart from the print head 19. The irradiation unit 26 irradiates ultraviolet light into the area of ​​the medium 30 where the index can be printed. The irradiation unit 26 may be movable under the control of the control unit 11, or it may be fixed in a non-movable state.

[0040] In step S110, the nozzle determination unit 12b refers to the "defective nozzle list" to determine whether or not there are any defective nozzles in the print head 19. If there are no defective nozzles, the determination is "No" and the process proceeds to step S170. On the other hand, if there is one or more defective nozzles, the determination is "Yes" and the process proceeds to step S120. The defective nozzle list is information stored in the storage unit 15 and is a list that registers the results of the defective nozzle detection process performed by the defective nozzle detection unit 20 so far. Each nozzle 21 of the first printing unit 24 of the print head 19 is identified by ink color and nozzle number. The nozzle number is, for example, a number assigned sequentially to the position of each nozzle 21 along the width direction D2. The defective nozzle list registers information about the nozzles 21 that have been detected as defective nozzles, for example, "Nozzle number 50 of C". Therefore, if one or more defective nozzles are registered in the defective nozzle list, the nozzle determination unit 12b determines "Yes" in step S110. The defective nozzle list also includes defective nozzles that were detected when the target frame was a frame downstream from the current target frame.

[0041] In step S120, the print data generation unit 12a corrects the print data for nozzle interpolation. Nozzle interpolation is a process that makes dots caused by defective nozzles less visible on the medium 30 by compensating for them with ink ejection from nozzles 21 in the vicinity of the defective nozzle. Nozzle interpolation is also called proximity interpolation. Typically, a nozzle 21 in the vicinity of a defective nozzle is a nozzle 21 that ejects ink of the same color as the defective nozzle and is adjacent to the defective nozzle in the width direction D2. In addition, a nozzle 21 that ejects ink of a different color than the defective nozzle and whose position coincides with or is adjacent to the defective nozzle in the width direction D2 may also be included as a nozzle 21 in the vicinity of a defective nozzle.

[0042] The print data generation unit 12a applies corrections for nozzle interpolation to the print data generated in step S100, which is the print data to be used for the pass to be executed on the target frame. For example, if it is the time to execute the first pass on the target frame, the print data for printing on the target frame, which is the print data to be used for the first pass, is corrected. Specifically, among the pixels that make up the print data, the dots defined in the pixels at the position to be printed by the nozzle 21 near the defective nozzle (hereinafter referred to as "neighboring pixels") are replaced with larger dots. For example, if a dot off is defined in a neighboring pixel, it is replaced with a small dot on. Also, if a small dot on is defined in a neighboring pixel, it is replaced with a medium dot on or a large dot on. The print data generation unit 12a performs such corrections to neighboring pixels for each defective nozzle registered in the defective nozzle list.

[0043] In step S130, the print data generation unit 12a branches the process depending on whether the pass to be executed is the last pass to the target frame. As mentioned above, if N=4, the fourth pass to the target frame is the last pass. Therefore, if the first three passes to the target frame have been completed and it is now time to execute the fourth pass, step S130 determines "Yes" and proceeds to step S140. On the other hand, if the third pass to the target frame has not yet been completed, step S130 determines "No" and proceeds to step S170. If N=1, step S130 is always "Yes".

[0044] In step S140, the print data generation unit 12a branches the process depending on whether the "defective nozzle flag" is on or off. As will be explained in detail later, the defective nozzle flag is a flag that is switched from off to on in step S210 when a new defective nozzle is detected, and this is also stored in the memory unit 15. If the defective nozzle flag is on, the print data generation unit 12a proceeds from "Yes" in step S140 through step S150 to step S170, while if the defective nozzle flag is off, it proceeds from "No" in step S140 to step S170.

[0045] In step S150, the print data generation unit 12a generates index data, then in step S160 switches the defective nozzle flag from on to off, and proceeds to step S170. Index data is print data for printing an index onto the medium 30 using a special liquid. The index can be any shape or design of mark or symbol. In the example in Figure 5, the index 32 is a triangular mark, so the index data is, for example, data representing such an index 32.

[0046] In step S170, the print control unit 12c controls the carriage 18 and the print head 19 to execute a pass once and print the image with ink. In step S170, which follows "No" in step S110, the print control unit 12c executes one of the passes that should be executed at that time for the target frame, i.e., one of the 1st to Nth passes, based on the print data corresponding to the pass. The pass executed in step S170, which follows "No" in step S110, performs ink ejection based on print data that has not been corrected for nozzle interpolation.

[0047] In step S170, which follows "No" in step S130, the print control unit 12c executes the pass that should be executed at that time to the target frame, that is, one of the 1 to N-1 passes, based on the print data corresponding to the pass, which has been corrected in step S120. In step S170, which follows "No" in step S140, the print control unit 12c executes the final pass to the target frame, i.e., the Nth pass, based on the print data corresponding to the Nth pass, which has undergone the correction in step S120.

[0048] In step S170, which follows step S150, the print control unit 12c executes the Nth pass to the target frame based on the print data corresponding to the Nth pass, which has been corrected in step S120. Furthermore, in this Nth pass, the print control unit 12c also performs the ejection of the special liquid by the second printing unit 25 based on the index data, i.e., prints the index. Note that the timing for switching the defective nozzle flag from on to off after generating the index data in step S150 may be at the timing of step S160 shown in Figure 3, or at the timing after the pass has been completed in step S170 following step S150.

[0049] After one pass is executed in step S170, in step S180, the nozzle determination unit 12b causes the defective nozzle detection unit 20 to perform a defective nozzle detection process targeting the first printing unit 24. In other words, in this embodiment, the defective nozzle detection process is performed after each pass is completed.

[0050] In step S190, the nozzle determination unit 12b branches the process depending on whether a new defective nozzle was detected in step S180. A new defective nozzle refers to a nozzle 21 that was not detected as a defective nozzle before the execution of the most recent step S180, but was detected as a defective nozzle by the defective nozzle detection process in the most recent step S180. A nozzle 21 that was detected as a defective nozzle before the most recent step S180 and was also detected as a defective nozzle in the most recent step S180 is not a new defective nozzle. If a new defective nozzle is detected in step S180, the nozzle determination unit 12b proceeds from the "Yes" determination in step S190 to step S200. If no new defective nozzle is detected in step S180, the nozzle determination unit 12b proceeds from the "No" determination in step S190 to step S220.

[0051] In step S200, the nozzle determination unit 12b updates the defective nozzle list by registering the newly detected defective nozzle in step S180 into the defective nozzle list. Newly registered defective nozzles in the defective nozzle list are subsequently subject to nozzle replacement, just like the defective nozzles already registered. In step S210, the nozzle determination unit 12b switches the defective nozzle flag from off to on and proceeds to step S220. If the defective nozzle flag is already on at step S210, it should remain on.

[0052] In step S220, the print data generation unit 12a determines whether or not printing of the image to the target frame has finished. If the pass executed in the most recent step S170 is the last pass to the target frame, i.e., the Nth pass, then printing of the image to the target frame can be said to be finished, and the unit determines "Yes" in step S220 and terminates the flowchart in Figure 3. On the other hand, if the pass executed in the most recent step S170 is not the Nth pass to the target frame, the unit determines "No" in step S220 and repeats steps S100 onward to perform the next pass to the target frame. In step S100, which follows a "No" in step S220, if print data for each pass used for printing to the target frame has already been generated, there is no need to generate print data again, so in effect, step S100 can be skipped and the determination in step S110 can be performed.

[0053] The lower section of Figure 5 shows the state after the flowchart in Figure 3, with frame 302 as the target frame, has finished, and the transport unit 17 has finished transporting one frame of the medium 30. This lower section of Figure 5 can also be said to indicate the point at which the flowchart in Figure 3 begins anew, with frame 303, which is adjacent to frame 302 on the upstream side, as the target frame. According to the lower section of Figure 5, image 31 and index 32 are printed on frame 302. Since index 32 is printed with UV-emitting ink as a special liquid, it is not visible to the user in the state shown in Figure 5.

[0054] As can be seen from the explanation so far, the fact that index 32 is printed on frame 302 means that a new defective nozzle was detected before the final pass to frame 302 was executed in the flowchart of Figure 3, which uses frame 302 as the target frame. In other words, at least one of the 1 to N-1 passes to frame 302 was executed without nozzle completion for the new defective nozzle that was present. Therefore, index 32 is printed in frame 302 along with the image on the Nth pass to frame 302 to indicate the possibility of a missing dot. According to Figures 3 and 5, the control unit 11 prints a specific mark using a special liquid by the second printing unit 25 on the "first frame" of the medium 30, which was printed by ink ejection with a defective nozzle in the first printing unit 24. In the example so far, frame 302 corresponds to the first frame.

[0055] Figure 4 shows a flowchart illustrating a part of the print control process that is not represented in Figure 3. Figure 4 will be explained assuming the flowchart in Figure 3, with frame 302 as the target frame, has finished. In other words, the "Yes" in step S300 of Figure 4 is the same as the "Yes" in step S220 when frame 302 was the target frame.

[0056] After "Yes" in step S300, in step S310, the print data generation unit 12a branches the process depending on whether the defective nozzle flag is on or off. If the defective nozzle flag is on, the print data generation unit 12a proceeds from "Yes" in step S310 to step S320; if the defective nozzle flag is off, it determines "No" in step S310 and terminates the flowchart in Figure 4.

[0057] The fact that the defective nozzle flag is ON at step S310 means that, in the flowchart of Figure 3 when frame 302 is the target frame, a new defective nozzle was detected in step S180 after the Nth pass to frame 302, and the defective nozzle flag was switched ON in step S210. In this case, the index could not be printed for printing to frame 302. Therefore, in step S320, the print data generation unit 12a generates index data.

[0058] In step S330, the print control unit 12c controls the carriage 18 and print head 19 to execute one pass, and the second printing unit 25 ejects the special liquid based on the index data generated in step S320, i.e., prints the index. Then, in step S340, the print data generation unit 12a switches the defective nozzle flag from on to off, ending the flowchart in Figure 4.

[0059] Furthermore, the "Yes" in step S220 when frame 302 was the target frame, that is, the "Yes" in step S300, also serves as the condition for starting the flowchart in Figure 3 when the next frame, 303, is the target frame. Therefore, the flowchart in Figure 4 is a process that is performed in parallel with the flowchart in Figure 3 when frame 303 is the target frame, and the actual step S330 is part of the path of step S170 to frame 303.

[0060] Specifically, if the print control unit 12c completes the flowchart in Figure 3 with frame 302 as the target frame with the defective nozzle flag set to ON, then in the subsequent flowchart in Figure 3 with frame 303 as the target frame, the first pass to the target frame involves the ejection of ink by the first printing unit 24 and the ejection of a special liquid by the second printing unit 25, printing the image and index onto frame 303. By switching the defective nozzle flag to OFF in step S340 immediately after step S170, which also involves index printing in step S330, the defective nozzle flag will be OFF at the first step S180 in the flowchart of Figure 3.

[0061] Figure 6 is a diagram illustrating a specific example of the first embodiment. The way to read Figure 6 is the same as the way to read Figure 5. Only the differences between Figure 6 and Figure 5 will be explained. The lower part of Figure 6 shows the state in which at least one pass has been completed in the flowchart of Figure 3 with frame 303 as the target frame. In the lower part of Figure 6, unlike the lower part of Figure 5, index 32 is not printed on frame 302 after printing is complete, and instead index 33 is printed on frame 303. In other words, in the example of Figure 6, because the flowchart of Figure 3 with frame 302 as the target frame was completed with the defective nozzle flag = ON, step S170, which also serves as step S330 in Figure 4, prints index 33 on frame 303 along with image 31a. Image 31a can be understood as the state before reaching image 31, which is completed in N passes.

[0062] Index 33 is an index printed based on the index data generated in step S320. In other words, the Nth pass to frame 302 was performed without nozzle completion for a new defective nozzle that was present. Therefore, to indicate the possibility of missing dots, index 33 is printed in the frame 303 that follows frame 302. As shown in Figures 4 and 6, the control unit 11 prints a specific mark using a special liquid with the second printing unit 25 on the "second frame" that is the target of printing by the first printing unit 24 after the first frame which was printed by ink ejection with a defective nozzle in the first printing unit 24. If frame 302 is the first frame, then frame 303 is the second frame.

[0063] Since indices 32 and 33 both indicate the possibility of missing pixels in image 31 printed on frame 302, there is little need to print both of them. Therefore, even if the print data generation unit 12a determines "Yes" in step S310 in Figure 4, if the index has already been printed on the Nth pass to the frame adjacent downstream of the current target frame, it may skip steps S320 and S330 and proceed to step S340 to complete the flowchart in Figure 4.

[0064] As mentioned above, both indices 32 and 33 are markers relating to frame 302, but as shown in Figures 5 and 6, indices 32 and 33 differ in their position, shape, and design within the frame. If indices 32 and 33 were the same in terms of position and appearance within the frame, a user viewing index 33 would not be able to determine whether index 33 relates to frame 302 or 303. Therefore, the control unit 11 makes it easier to distinguish which frame an index relates to by making the position and appearance of indices 32 and 33 different within the frame. For example, if the index is triangular or printed on the upstream side within the frame, as shown in Figure 5, it can be determined that it is a marker relating to the image in the frame on which the index is printed. On the other hand, if the index is star-shaped or printed on the downstream side within the frame, as shown in Figure 6, it can be determined that it is a marker relating to the image in the frame adjacent to the downstream side of the frame on which the index is printed.

[0065] As each frame being transported downstream by the transport unit 17 passes under the irradiation unit 26, it is irradiated with ultraviolet light from the irradiation unit 26. Therefore, if an index is printed on the frame, the index will glow when irradiated with ultraviolet light, making it visible to the user. The user then visually inspects the image 31 of the frame related to the index and evaluates the presence and extent of any defects such as dead pixels. If the image quality of the printed frame indicated by the index is acceptable, the user can use that printed product as a product; if there are problems with the image quality, they can not use it as a product. The index is printed with a special liquid, which is invisible unless irradiated with ultraviolet light, or becomes invisible after a certain amount of time or when a certain amount of heat is applied. Therefore, frames with printed indexes can also be used as one of the products.

[0066] Alternatively, the printing device 10 may have a sensor or camera downstream of the print head 19 that can detect an index printed with a special liquid, and the sensor or camera may automatically detect the index from the frame being transported. When an index is detected from a frame by the sensor or camera, the user can visually evaluate the frame indicated by the detected index.

[0067] As described above, according to the first embodiment, the control unit 11 prints an image with ink in N passes for each frame. In this case, if a new defective nozzle is detected after the start of printing to the first frame but before the Nth pass is executed, the special liquid is ejected along with the ink in the Nth pass, and the index is printed to the first frame. On the other hand, if a new defective nozzle is detected in step S180 after the execution of the Nth pass to the first frame, the index cannot be printed to the first frame, so the special liquid is ejected along with the ink to the second frame, and the index is printed.

[0068] 3. Second Embodiment: Next, a second embodiment will be described. For each of the following embodiments, including the second embodiment, descriptions common to the first embodiment will be omitted. In the second embodiment, if the control unit 11 detects a new defective nozzle between the start of printing to the first frame and the start of printing to the second frame, it ejects a special liquid along with ink to the second frame and prints the index, regardless of whether the detection of the new defective nozzle occurs before or after the Nth pass to the first frame. In other words, in the second embodiment, steps S130, S140, S150, and S160 in the flowchart of Figure 3 are omitted.

[0069] The control unit 11, for example, with frame 302 as the target frame, executes step S170 after step S120 in the process of executing the flowchart in Figure 3. This second embodiment is largely comprised of the explanation of Figure 3, omitting steps S130, S140, S150, and S160, and the explanations of Figures 4 and 6. In the second embodiment, "Yes" in step S310 means that, in the flowchart in Figure 3 when frame 302 is the target frame, a new defective nozzle was detected in step S180 after any of the 1 to N passes to frame 302, and the defective nozzle flag was switched on in step S210. According to the second embodiment, the processing can be simplified compared to the first embodiment, and the necessary index can be printed on the medium 30.

[0070] 4. Third Embodiment: Figure 7 is a diagram illustrating a specific example of the third embodiment. The way to read Figure 7 is the same as the way to read Figures 5 and 6. In Figure 7, the movable range of the carriage 18 parallel to the transport direction D1 is shown as the movement range W2. Compared to the movement range W1 shown in Figures 5 and 6, the movement range W2 is wider. In other words, in the third embodiment, the print head 19 can print not only on the target frame but also on a portion of the frame adjacent to the target frame downstream, and on a portion of the frame adjacent to the target frame upstream, while the media 30 is stationary.

[0071] In the third embodiment, when a new defective nozzle is detected after the start of printing to the first frame but before the Nth pass is executed, the Nth pass is performed. hand The process of printing an index to the first frame is the same as in the first embodiment. In the third embodiment, if the control unit 11 detects a new defective nozzle in step S180 after the Nth pass to the first frame, it prints an index to the first frame with the second frame as the target frame.

[0072] The upper part of Figure 7, similar to the lower part of Figure 5, shows the state after the flowchart of Figure 3, with frame 302 as the target frame, has finished, and the transport unit 17 has finished transporting one frame of the medium 30. According to the upper part of Figure 7, unlike the lower part of Figure 5, the index 32 is not printed on frame 302.

[0073] The lower section of Figure 7, similar to the lower section of Figure 6, shows the state after at least one pass has been completed in the flowchart of Figure 3 with frame 303 as the target frame. In the lower section of Figure 7, unlike the lower section of Figure 6, index 32 is printed on frame 302. In the example of Figure 7, the control unit 11 prints the index by step S170, which also serves as step S330 in Figure 4, because the flowchart of Figure 3 with frame 302 as the target frame ended with the defective nozzle flag = ON. In this case, in the pass to print image 31a to frame 303, which is the target frame, the carriage 18 is moved to a part of frame 302, thereby printing index 32 on frame 302. In the example of Figure 7, index 32 is printed based on the index data generated in step S320. According to the third embodiment, even after the target frame switches from the first frame to the second frame, the index related to the first frame can be printed on the first frame.

[0074] 5. Fourth Embodiment: Previously, the second printing unit 25, together with the first printing unit 24, was part of the print head 19 and mounted on the carriage 18. However, in the fourth embodiment, the second printing unit 25 is not mounted on the carriage 18. The second printing unit 25 is positioned at a predetermined location downstream of the print head 19 having the first printing unit 24.

[0075] Figure 8 is a diagram illustrating a specific example of the fourth embodiment. The way to read Figure 8 is the same as the way to read Figures 5 to 7. According to Figure 8, the second printing unit 25 is located downstream of the carriage 18 and the print head 19, and is fixed in a position where it can print on adjacent frames downstream of the target frame using a special liquid. The second printing unit 25 is also located upstream of the illumination unit 26. In the fourth embodiment, the printing of the index by the second printing unit 25 is a process independent of the pass by the print head 19. Therefore, the control unit 11 does not execute steps S130, S140, S150, and S160 in the flowchart of Figure 3 for the target frame. Furthermore, step S330 in the flowchart of Figure 4 refers only to the printing of the index by the second printing unit 25, and not part of the pass by the print head 19.

[0076] The upper part of Figure 8, similar to the upper parts of Figures 5 and 6, shows the point at which the flowchart in Figure 3 begins, with frame 302 as the target frame. The lower part of Figure 8, similar to the lower parts of Figures 6 and 7, shows the state after at least one pass has been completed in the flowchart in Figure 3, with frame 303 as the target frame. According to the lower part of Figure 8, in parallel with the printing of image 31a to frame 303 according to the flowchart in Figure 3, the index 32 is printed by the second printing unit 25 to frame 302, which is adjacent to frame 303 downstream, according to the flowchart in Figure 4. In Figure 8, the index 32 printed in a position overlapping with the second printing unit 25 is shown with a dashed line. According to the fourth embodiment, the second printing unit 25 is separated from the print head 19, which is the first printing unit 24, and is positioned downstream of the first printing unit 24. This makes it possible to print the necessary index on a frame that has already been printed with ink, independently of the ink printing on the target frame.

[0077] 6. Fifth Embodiment: The control unit 11 may print the mark, or index, at a position in the first or second frame corresponding to a "defective raster line" printed using a nozzle 21 containing one or more defective nozzles within the first frame. Printing using a nozzle 21 containing one or more defective nozzles includes both cases: printing using only defective nozzles, i.e., cases where printing is substantially not performed due to dot defects, and cases where printing is performed using both defective nozzles and normal nozzles 21. The fifth embodiment and the sixth embodiment described later can be combined with any of the embodiments.

[0078] Figure 9 is a diagram illustrating a specific example of the fifth embodiment, showing a magnified view of parts of frame 302 and frame 303 of the medium 30 compared to Figure 5, etc. In Figure 9, an image 31 is printed on frame 302 through N passes, and an index 32 related to frame 302 is also printed. The index related to frame 302 may, of course, be printed on frame 303 instead of frame 302. In Figure 9, one raster line RL1 is illustrated with a dashed line. Also in Figure 9, several raster lines RL2, RL3 within frame 302 that were printed with missing dots are clearly illustrated. In other words, in the flowchart of Figure 3 executed with frame 302 as the target frame, at least one of the N passes resulted in missing dots in some raster lines RL2, RL3 due to a new defective nozzle that was not yet registered in the defective nozzle list as a target for nozzle completion. Such raster lines RL2, RL3 correspond to defective raster lines.

[0079] As illustrated in Figure 9, the control unit 11 prints the index 32 at a position corresponding to a defective raster line using the second printing unit 25. The position corresponding to a defective raster line is the position that coincides with or nearly coincides with the defective raster line in the direction intersecting the longitudinal direction of the raster line, that is, in the width direction D2 in the figure. The control unit 11 identifies the position corresponding to the defective raster line according to the position of a new defective nozzle in the nozzle group 22C, 22M, 22Y, 22K, and then has the second printing unit 25 print the index 32 at the identified position using a special liquid. Thus, according to the fifth embodiment, since the index is printed at a position corresponding to a defective raster line in the first or second frame, the user can easily recognize the position of the defective raster line according to the index and efficiently determine whether the image quality of the frame as a printed result is good or not.

[0080] 7. Sixth Embodiment: The control unit 11 may use a special liquid in the second printing unit 25 to print character information indicating the position and / or number of "defective raster lines" printed using nozzle 21 which includes one or more defective nozzles among the raster lines in the first frame onto the first or second frame. The control unit 11 prints this character information along with the index using the special liquid at the same time as printing the index described above. The character information may be considered as part of the index. The position of a defective raster line is, for example, the position corresponding to a defective raster line among the positions pre-assigned to each raster line in the width direction D2. Alternatively, the nozzle number may be treated as the position of the raster line.

[0081] In the flowchart of Figure 3, with frame 302 as the target frame, the control unit 11 recognizes, for example, raster lines RL2 and RL3 as defective raster lines, as shown in Figure 9, based on the detection results of a new defective nozzle. In this situation, the control unit 11 prints a string indicating either the position of raster lines RL2 and RL3, or the number "2", or both, along with an index, onto frame 302 or frame 303 using a special liquid. According to this sixth embodiment, the user can learn more detailed information about the defective raster lines by recognizing the character information printed with the special liquid.

[0082] 8. Summary: As described above, according to this embodiment, the printing apparatus 10 includes a first printing unit 24 having a plurality of nozzles 21 for ejecting ink onto a medium 30, a second printing unit 25 capable of printing onto the medium 30 using a special liquid, a defective nozzle detection unit 20 capable of detecting defective nozzles among the plurality of nozzles 21, and a control unit 11 that controls the first printing unit 24 and the second printing unit 25. The special liquid is a liquid that becomes invisible depending on the elapsed time since printing onto the medium 30 or the environment in which the printing result of the medium 30 is visible. The control unit 11 uses the second printing unit 25 to print a specific mark using the special liquid onto a first frame, which is a frame as a printing unit area on the medium 30, that has been printed by ejecting ink while a defective nozzle is included in the first printing unit 24, or onto a second frame, which is the next frame to be printed by the first printing unit 24 after the first frame.

[0083] According to the above configuration, a specific mark, or index, is printed onto the first or second frame using a special liquid. Therefore, the user can evaluate the image quality of the first frame as a printed product according to the index, and the first or second frame as a printed product can be used as a product with the index still printed on it. In other words, it avoids the situation where the printed product cannot be used as a product or its range of use is limited due to the presence of inspection marks, as in the past, and prevents the waste of resources such as the medium 30 and ink.

[0084] Furthermore, according to this embodiment, the printing apparatus 10 uses UV-emitting ink as a special liquid that emits visible light when irradiated with ultraviolet light. It also has an irradiation unit 26 that irradiates ultraviolet light onto the area of ​​the medium 30 where the mark can be printed. According to the above configuration, the presence of the index can be confirmed by irradiating the medium 30 with the irradiation unit 26, enabling the necessary image quality evaluation, while ensuring that the index is not visible under normal conditions.

[0085] Furthermore, according to this embodiment, the control unit 11 may print the mark at a position in the first frame or the second frame that corresponds to a defective raster line printed using a nozzle 21 that includes one or more defective nozzles among the raster lines in the first frame. According to the above configuration, users can easily recognize the location of defective raster lines according to the index and efficiently evaluate the image quality of the first frame as a printed result.

[0086] Furthermore, according to this embodiment, the control unit 11 may use a special liquid in the second printing unit 25 to print character information indicating the position and / or number of defective raster lines printed using a nozzle 21 that includes one or more defective nozzles among the raster lines in the first frame onto the first frame or the second frame. According to the above configuration, users can recognize the character information printed with the special liquid, thereby obtaining more detailed information about defective raster lines and using this information to evaluate image quality.

[0087] This embodiment discloses inventions in various categories, not limited to devices or systems, but also including methods executed by devices or systems, and programs 12 that cause a processor to execute these methods. This embodiment discloses a printing method using a printing apparatus 10, for example, which includes a first printing unit 24 having a plurality of nozzles 21 for ejecting ink onto a medium 30. The printing apparatus 10 has a second printing unit 25 capable of printing onto the medium 30 using a special liquid, the special liquid being a liquid that becomes invisible depending on the elapsed time since printing onto the medium 30 or the environment in which the printing result on the medium 30 is visible. The printing method comprises a first printing step in which the first printing unit 24 ejects ink and prints onto a frame, which is a printing unit area on the medium 30; a defective nozzle detection step in which a defective nozzle is detected from among the plurality of nozzles 21; and a second printing step in which the second printing unit 25 prints a specific mark using the special liquid onto a first frame that has been printed by ejecting ink while a defective nozzle is included in the first printing unit 24, or onto a second frame that is the next target of printing by the first printing unit 24 after the first frame. According to Figures 3 and 4, step S170 corresponds to the first printing process. Step S330 and some parts of step S170 correspond to the second printing process, and step S180 corresponds to the defective nozzle detection process.

[0088] The second printing unit 25 is not limited to a configuration that uses a nozzle 21 to dispense the special liquid, as it only needs to be capable of printing with the special liquid. For example, the second printing unit 25 may be a movable stamp under the control of the control unit 11, and may be configured to print an index by contacting the medium 30 and adhering the special liquid to the medium 30.

[0089] The medium 30 does not have to be a medium consisting of multiple connected frames, such as the roll paper shown in Figure 5. The medium 30 may also be single sheets of paper cut into individual units. In this case, one sheet of single paper corresponds to one frame, and the transport unit 17 only needs to transport multiple sheets of single paper in succession.

[0090] The printing device 10 can perform a so-called cleaning at any time to restore the function of the print head 19. Cleaning clears the clogging of the nozzles 21 and returns the faulty nozzles to normal. Therefore, the control unit 11 may, upon performing cleaning of the print head 19, delete the registration of the faulty nozzles in the faulty nozzle list and initialize the faulty nozzle list. [Explanation of symbols]

[0091] 10…Printing device, 11…Control unit, 12…Program, 12a…Print data generation unit, 12b…Nozzle determination unit, 12c…Print control unit, 13…Display unit, 14…Operation reception unit, 15…Storage unit, 16…Communication IF, 17…Transport unit, 18…Carriage, 19…Print head, 20…Defective nozzle detection unit, 21…Nozzle, 22,22C,22M,22Y,22K,22S…Nozzle group, 23…Platen, 24…First printing unit, 25…Second printing unit, 26…Irradiation unit, 30…Media, 31…Image, 32,33…Index, 301,302,303,304…Frame, RL1,RL2,RL3…Raster line

Claims

1. A first printing unit having multiple nozzles for ejecting ink onto a medium, A second printing unit capable of printing onto the medium using a special liquid, A defective nozzle detection unit capable of detecting a defective nozzle among multiple nozzles, The system comprises a control unit that controls the first printing unit and the second printing unit, The control unit completes printing by executing N passes for a single frame, which is a printing unit area on the medium, and repeats the printing for each frame for a plurality of frames, and causes the defective nozzle detection unit to execute a process to detect the defective nozzle after each pass is completed. The special liquid is a liquid that becomes invisible depending on the time elapsed since printing on the medium or the environment in which the printed result of the medium is visible. The printing apparatus is characterized in that the control unit can determine whether a new defective nozzle is detected after the N-1th pass and whether a new defective nozzle is detected after the Nth pass, and the second printing unit prints a specific mark using the special liquid on a first frame that has been printed by the ejection of the ink while the defective nozzle is included in the first printing unit, or on a second frame that is to be printed by the first printing unit after the first frame.

2. The control unit is If a new defective nozzle is detected after the N-1th pass, the second printing unit prints the specific mark on the first frame using the special liquid. The printing apparatus according to claim 1, characterized in that if a new defective nozzle is detected after the Nth pass, the second printing unit prints the specific mark on the second frame using the special liquid.

3. The printing apparatus according to claim 1 or 2, characterized in that the control unit prints the specific mark using the special liquid by the second printing unit such that the position within the frame differs depending on whether a new defective nozzle is detected after the N-1th pass or after the Nth pass has been completed.

4. The printing apparatus according to any one of claims 1 to 3, characterized in that the control unit prints the specific mark using the special liquid with the second printing unit such that the shape differs depending on whether a new defective nozzle is detected after the N-1th pass or after the Nth pass has been completed.

5. The aforementioned special liquid is a UV-emitting ink that emits visible light when irradiated with ultraviolet light. The printing apparatus according to any one of claims 1 to 4, characterized in that it has an irradiation unit for irradiating ultraviolet light onto an area of ​​the medium on which the mark can be printed.

6. The printing apparatus according to any one of claims 1 to 5, characterized in that the control unit prints the mark at a position in the first frame or the second frame corresponding to a defective raster line printed using one or more nozzles that include the defective nozzles among the raster lines in the first frame.

7. The printing apparatus according to any one of claims 1 to 6, characterized in that the control unit prints character information indicating the position and / or number of defective raster lines printed using the nozzles that include one or more defective nozzles among the raster lines in the first frame, on the first frame or the second frame using the special liquid by the second printing unit.

8. A printing method using a printing apparatus comprising a first printing unit having multiple nozzles for ejecting ink onto a medium, The printing apparatus has a second printing unit capable of printing onto the medium using a special liquid, The special liquid is a liquid that becomes invisible depending on the time elapsed since printing on the medium or the environment in which the printed result of the medium is visible. The aforementioned printing method is A first printing step involves ejecting the ink from the first printing unit and printing onto a frame, which is a printing unit area on the medium. A defective nozzle detection step for detecting a defective nozzle among a plurality of the aforementioned nozzles, The process includes a second printing step in which the second printing unit prints a specific mark using the special liquid on a first frame, which has been printed by the ejection of the ink while the first printing unit contains the defective nozzle, or on a second frame, which is to be printed by the first printing unit after the first frame. In the first printing step, printing is completed by performing N passes for one frame, and the printing of each frame is repeated for multiple frames. In the defective nozzle detection step, a process for detecting the defective nozzle is executed after each pass is completed. The printing method is characterized in that, in the second printing step, the second printing unit prints the specific mark on the first frame or the second frame of the plurality of frames using the special liquid, so as to be able to determine whether a new defective nozzle is detected after the N-1 passes have been completed or whether a new defective nozzle is detected after the Nth pass has been completed.

Images