Recording device, control method thereof, program, and storage medium

Abstract

To provide a recording device capable of recording a printed matter of image quality appropriate for a user.SOLUTION: A recording device includes: an inspection part that inspects a discharge state of a plurality of nozzles of a recording head having the plurality of nozzles that discharge liquid; a correction part that corrects the discharge state of the plurality of nozzles on the basis of an inspection result by the inspection part; and a first determination part that determines whether or not there is a failure in the recording head on the basis of a difference between a discharge state immediately before correction of the discharge state of the plurality of nozzles and a discharge state of the plurality of nozzles in recording operation.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a recording apparatus that records an image by depositing ink or the like on a recording medium. [Background technology]

[0002] 2. Description of the Related Art Inkjet printers are known as devices that form images on a recording medium using a recording head having a plurality of nozzles that eject ink.

[0003] In recent years, the number of nozzles has tended to increase as print heads have become longer and nozzles have become denser. Increasing the number of nozzles is expected to improve the productivity of printed images, but it becomes difficult to maintain the normal ejection state of all nozzles. In addition, increasing the number of nozzle rows to improve the image quality of printed images also leads to an increase in the number of nozzles. There are various factors that can adversely affect the nozzle ejection state, such as adhesion of ink mist, air bubbles entering the ink flow path, and clogging of the ejection port due to foreign matter.

[0004] These factors cause ejection defects such as non-ejection of ink and ink distortion, which lead to deterioration of the quality of the printed image such as white streaks, etc. Therefore, when such ejection defects occur during printing operation, it is necessary to detect them promptly.

[0005] In response to this, Patent Document 1 describes an inkjet recording device that records a test pattern to detect ejection defects in the recording head between recording of a print image, and prints while detecting the ejection status of the recording head. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-252691 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, in the method disclosed in Patent Document 1, the number of non-ejecting nozzles in the print head is used as a criterion for detecting ejection defects in the print head. Therefore, there is a risk that the printout that is visually judged to be good by the user may be mistakenly judged to be defective by the print device. In other words, since the print device's judgment criteria may be higher than the user's criteria for judging whether the quality of the printout is good, it can be said that there is room to lower the level of the print device's judgment criteria.

[0008] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a recording apparatus capable of recording printed matter with an image quality that is appropriate for a user. [Means for solving the problem]

[0009] The recording device of the present invention is characterized by comprising an inspection means for inspecting the ejection state of a recording head having a plurality of nozzles that eject liquid, a correction means for correcting the ejection state of the plurality of nozzles based on the inspection results by the inspection means, and a first judgment means for judging whether or not a defect has occurred in the recording head based on the difference between the ejection state of the plurality of nozzles immediately before the ejection state is corrected and the ejection state of the plurality of nozzles during recording operation. Effect of the Invention

[0010] According to the present invention, it is possible to provide a recording device capable of recording a printout with an image quality that is appropriate for the user. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view showing the internal configuration of a recording apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] Schematic of the chip being attached to a recording head. [Figure 4] FIG. 4 is a perspective view of a housing of a sheet transport unit of the recording unit. [Diagram 5] FIG. [Figure 6] FIG. 2 is a block diagram showing the configuration of a control unit of the recording apparatus. [Figure 7] FIG. 4 is a diagram for explaining the flow of image processing in the first embodiment. [Figure 8] 11 is a flowchart showing a period during which non-discharge monitoring is performed. [Figure 9] 13 is a flowchart showing a non-discharge monitoring process. [Figure 10] FIG. 11 is a diagram for explaining the flow of image processing in the second embodiment. [Figure 11] 13A to 13C are views for explaining discharge failure complement processing in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0013] (First embodiment) First, the coordinate axes are defined as the top of the device in Figure 1 (z direction), the longitudinal direction (x direction) from right to left, and the sheet width direction (y direction) from the front to the back of the paper in the direction perpendicular to the sheet transport direction (x direction).

[0014] In this embodiment, a high-speed line printer that uses a continuous sheet wound in a roll as a recording medium will be described as an example. However, the present invention is also applicable to printers that use sheet-fed recording media, and to serial printers that record images on a recording medium by moving a carriage carrying a recording head in a direction intersecting the conveyance direction of the recording medium. In addition, the recording medium is not limited to paper, and various other types of recording media can be used as long as they are capable of being printed on.

[0015] 1 is a schematic cross-sectional view showing the internal configuration of a recording device 1. Inside the recording device 1 of this embodiment, there are arranged the following units: an unwinding roll section 2, a first dancer section 3, a first main transport section 4, a meandering correction section 5, a transport detection section 6, a recording section 7, a transport tension detection section 9, a recorded image position detection section 10, a scanner section 11, a second main transport section 12, a second dancer section 13, a winding roll section 14, a maintenance section 15, a drying section 40, and a cooling section 50. A continuous sheet S, which is a recording medium, is transported along a sheet transport path indicated by a solid line in the figure, and is processed in each unit.

[0016] In the recording device 1 of this embodiment, a first recording step and a second recording step are performed along the sheet transport path (sheet S). In the first recording step, an image is recorded on the sheet S by the processing of the first recording section 7a, the first drying section 40a, and the first cooling section 50a. In the second recording step, an image is recorded on the sheet S that has passed through the first recording step by the processing of the second recording section 7b, the second drying section 40b, and the second cooling section 50b. In this way, the recording device 1 can record images continuously on the sheet S by passing the sheet S through the first recording step and the second recording step. In addition, the recording device 1 can also determine the above recording step alternatively depending on the recording conditions. In that case, an image is recorded on the sheet S by only the selected recording step.

[0017] The unwinding roll unit 2 is a unit for holding and supplying a continuous sheet wound in a roll shape. The unwinding roll unit 2 is configured to store an unwinding roll and pull out and supply the sheet S. Note that the number of rolls that can be stored is not limited to one, and the unwinding roll unit 2 may store two or three or more rolls and selectively pull out and supply the sheet S.

[0018] The first dancer section 3 is a unit for applying a constant tension to the sheet S between the unwinding roll section 2 and the first main transport section 4. The first dancer section 3 applies tension to the sheet S using a tension applying means (not shown).

[0019] The first main conveyor 4 is a unit provided along the sheet conveying path (sheet S) for feeding the sheet S to each unit and applying tension to the sheet S between the first main conveyor 4 and the second main conveyor 12. The first main conveyor 4 rotates by driving a motor (not shown) and conveys the sheet S while applying tension to it.

[0020] The meandering correction unit 5 is a unit for correcting meandering in the width direction of the sheet S when the sheet S is conveyed with tension applied thereto. In this embodiment, the meandering correction unit 5 includes a first meandering correction unit 5a and a second meandering correction unit 5b, which are disposed upstream of each recording process in the sheet conveying path. The meandering correction unit 5 includes a meandering correction roller and a meandering detection sensor (not shown) that detects meandering of the sheet S. The meandering correction roller is driven by a motor (not shown) and is capable of changing the inclination of the sheet S, and corrects the meandering of the sheet S based on the measurement by the meandering detection sensor. The meandering correction function is improved by wrapping the sheet S around the meandering correction roller.

[0021] The transport detection unit 6 is a unit for detecting the transport speed of the sheet S and a mark printed in advance on the sheet S in order to control the image formation timing of the recording unit 7. In this embodiment, the transport detection unit 6 includes a first transport detection unit 6a and a second transport detection unit 6b arranged upstream of each recording process in the sheet transport path. The first transport detection unit 6a and the second transport detection unit 6b are used to control the image formation timing of the first recording unit 7a and the second recording unit 7b, respectively.

[0022] 2, the recording head 22 includes a lower base substrate 22a, which is a support member, and eight parallelogram-shaped chips 221 made of silicon and bonded to the lower base substrate 22a. The lower base substrate 22a is electrically connected to a flexible wiring board by wire bonding at electrodes on both ends of the lower base substrate 22a.

[0023] 3, the chip 221 has eight nozzle rows arranged perpendicular to the transport direction, namely, nozzle row A, nozzle row B, nozzle row C, nozzle row D, nozzle row E, nozzle row F, nozzle row G, and nozzle row H. There is no particular limit to the number of nozzle rows, and it may be, for example, 16 rows instead of 8 rows.

[0024] The recording unit 7 is a processing unit that applies a liquid composition (ink) from above to the conveyed sheet S by the recording head 22 to form an image. The conveying path in the recording unit 7 is formed by guide rollers 23 arranged in an upwardly convex arc shape, and a certain tension is applied to the sheet S to ensure a clearance with the recording head 22. The recording heads 22 are arranged in a plurality of recording heads along the conveying direction. In this embodiment, the first recording unit 7a has a total of two line-type recording heads, a head corresponding to W (white) ink and a head corresponding to the reaction liquid. The second recording unit 7b has four line-type recording heads corresponding to four colors, Bk (black), Y (yellow), M (magenta), and C (cyan). In addition to that, it has four line-type recording heads, a head corresponding to the reaction liquid, and a head corresponding to three special color inks, O (orange), G (green), and V (violet). In other words, the second recording unit 7b has a total of eight line-type recording heads. It should be noted that the types and number of colors and the number of recording heads 22 are not limited to the above example.

[0025] Here, the reaction liquid is a liquid containing a component that increases the viscosity of the ink. The increase in the viscosity of the ink refers to a state in which the coloring material, resin, etc. constituting the ink come into contact with the component that increases the viscosity of the ink, and undergo a chemical reaction or physical adsorption, resulting in an increase in the viscosity of the ink. The increase in the viscosity of the ink is not limited to an increase in the viscosity of the entire ink, but also includes a case in which a local increase in viscosity occurs due to partial aggregation of the components constituting the ink, such as the coloring material and resin. The component that increases the viscosity of the ink is not particularly limited to metal ions, polymer coagulants, etc., but a substance that causes a pH change in the ink and causes the coloring material in the ink to aggregate can be used, and an organic acid can be used. If a reaction liquid is applied before the ink is applied onto the sheet S, the ink that reaches the sheet S can be fixed immediately. This makes it possible to suppress bleeding, in which adjacent inks mix with each other. In addition, as the inkjet method, a method using a heating element, a piezoelectric method, a method using an electrostatic element, a method using a MEMS element, etc. can be adopted. The ink is supplied to the recording head 22 from an ink tank (not shown) through an ink tube.

[0026] 4, the sheet conveying unit housing 71 of the recording unit 7 is provided with a plurality of positioning members 711 for positioning the recording heads 22. The positioning members 711 are arranged at the front and rear of the sheet S in the width direction, sandwiching the sheet S therebetween, and one positioning member 711 is provided at the front side and two positioning members are provided at the rear side for each recording head 22 in FIG.

[0027] 5, the recording head 22 is supported by a support shaft 27 supported from below by a recording head holding section 26 for holding the recording head 22 and raising and lowering it up and down. The recording head holding section 26 is raised and lowered up and down along a lifting rail 29 provided in a recording head lifting frame 28 by a drive mechanism (not shown) provided inside. In the present embodiment, the liquid composition is applied onto the sheet S using an inkjet head, but the method of applying the liquid composition onto the sheet in the recording section 7 is not limited to this. For example, in the present embodiment, the reaction liquid is applied by the recording head 22, but it may be applied by a roller, a die coating device (die coater), a blade coating device (blade coater), or the like.

[0028] The conveying tension detection unit 9 is a unit for detecting tension when the sheet S is conveyed between the first main conveying unit 4 and the second main conveying unit 12 with tension applied thereto.

[0029] The recorded image position detection unit 10 is a unit for detecting misalignment of an image formed on the sheet S by the recording unit 7 during printing, and correcting the printing.

[0030] The winding guide roller R1 is a roller that winds the surface of the sheet S opposite to the ink application surface at a constant winding angle downstream of the second recording unit 7b in the transport direction. In this embodiment, two winding guide rollers R1 are arranged between the second recording unit 7b and the second drying unit 40b. The sheet S is folded back approximately parallel to the top and bottom of the device by the winding guide rollers R1, and the second drying unit 40b is arranged below the recording unit 7b.

[0031] The drying section 40 (first drying section 40a, second drying section 40b) is a unit that reduces the amount of liquid contained in the liquid composition applied to the sheet S in the recording section 7, and improves the fixation of the sheet S and the ink. The drying section 40 blows air onto the recorded sheet S to dry the applied ink. Inside the drying section 40, air is blown onto at least the ink-applied side of the sheet S passing through, drying the ink-applied side of the sheet S. Note that the drying method may be, in addition to the method of blowing air, a method of irradiating the surface of the sheet S with electromagnetic waves (ultraviolet rays, infrared rays, etc.) or a conductive heat transfer method by contact with a heating element, or a combination of these.

[0032] The cooling section 50 (first cooling section 50a, second cooling section 50b) has a function of cooling the sheet S fixed in the drying section 40, solidifying the softened ink, and suppressing the amount of temperature change of the sheet S in downstream processes of the recording device. Inside the cooling section 50, air at a lower temperature than the sheet S is blown onto at least the ink-applied surface side of the passing sheet S to cool the ink-applied surface of the sheet S. Note that the cooling method is not limited to the method of blowing air, and a conductive heat transfer method using contact with a heat dissipating member may also be used, or a combination of these may be used.

[0033] The scanner unit 11 is a unit for reading an image formed on the sheet S by the recording unit 7 during printing, and changing the operating conditions of the recording head 22 using the analyzed parameters. For example, it is used to adjust the operation timing in order to match the dot positions of different colors. It is also used to perform shading for the purpose of reducing the variation between recording elements (nozzles) of the recording head 22.

[0034] The second main transport section 12 is a unit that transports the sheet S between the first main transport section 4 while applying tension to the sheet S, and adjusts the tension of the sheet S. The second main transport section 12 has rollers driven by a motor (not shown), and controls the rotation speed of the rollers in the second main transport section 12 according to the tension value detected by the transport tension detection section 9. Note that, as a configuration for adjusting the tension of the sheet S, a configuration for adjusting the tension of the sheet S by a clutch (not shown) capable of controlling the torque connected to the drive may be added. In this case, two methods of tension control are possible: a torque control method for controlling the torque value transmitted from the clutch, and a speed control method for controlling the speed of the rollers of the second main transport section 12. Depending on the purpose, these tension control methods can be switched or both can be used simultaneously.

[0035] The second dancer section 13 is a unit for applying a constant tension to the sheet S between the second main transport section 12 and the winding roll section 14. The second dancer section 13 applies tension to the sheet S by a tension applying means (not shown).

[0036] The winding roll unit 14 is a unit for winding the sheet S after the recording process onto a core. The number of recoverable rolls is not limited to one. It may have two or three or more cores and be configured to selectively switch between them to recover the sheet S. Depending on the content of the post-recording processing, instead of winding the sheet S onto a core, it may be configured to cut the continuous sheet using a cutter and stack the cut sheet S.

[0037] 6 is a block diagram showing the control configuration of the recording device 1. The control unit 31 is a unit that controls each part of the entire recording device. The control unit 31 has a CPU 34, a storage device 35 that stores various information such as the discharge speed and the thickness of the recording medium, a controller equipped with various control units, an external interface, and an operation unit 32 where the user performs input and output. The CPU 34, the storage device 35, and the various control units are connected to each other so that they can communicate with each other via an internal bus. The operation of the recording device 1 is controlled by the CPU 34 based on instructions from the controller or a host device 33 such as a host computer connected to the controller via an external interface.

[0038] When a command to start a printing operation is issued from the host device 33, transport of the sheet S is started under the control of the CPU 34 in accordance with various programs and parameters stored in the storage device 35. That is, the transport operation is started by operating the first dancer section 3, the second dancer section 13, the unwinding roll section 2, the winding roll section 14, the first main transport section 4, the second main transport section 12, the meandering correction section 5, the transport detection section 6, and the transport tension detection section 9. Here, the various parameters necessary to perform the transport operation are selected according to the type of the sheet S used to record image data.

[0039] The image data transmitted from the host device 33 is converted into an ejection signal through predetermined image processing by the image processing unit 36. Recording on the sheet S is performed by the above-mentioned conveying operation and the ejection of ink from the recording head 22 according to the converted ejection signal.

[0040] The maintenance unit 15 is a unit equipped with a mechanism for recovering the ejection performance of the recording head 22. Examples of such mechanisms include a cap mechanism for protecting the ink ejection surface of the recording head 22, a wiper mechanism for wiping the ink ejection surface, and a suction mechanism for negatively sucking the ink in the recording head 22 from the ink ejection surface. The maintenance unit 15 also has a drive mechanism and rails (not shown) and can move back and forth in the sheet width direction along the rails. When performing maintenance on the recording head 22, the maintenance unit 15 moves to a position immediately below the recording head 22, and when maintenance is not performed, the maintenance unit 15 moves to a position retracted from immediately below the recording head 22. In this embodiment, a first maintenance unit 15a and a second maintenance unit 15b are provided corresponding to the first recording unit 7a and the second recording unit 7b, respectively.

[0041] Incidentally, the recorded image position detection unit 10, the scanner unit 11, the drying unit 40, and the cooling unit 50 are configured as described above, and are connected to the CPU 34 via an internal bus.

[0042] FIG. 7 is a diagram showing the flow of image processing performed by the image processing unit 36 ​​provided in the control unit 31 in the first embodiment.

[0043] In the recording device 1 of this embodiment, RGBW multi-value data is input from the host device 33 to the control unit 31 based on image data input by the user to the operation unit 32. The RGBW conversion unit 301 converts the input RGBW data to data suitable for color reproduction by the recording device 1, and generates R'G'B'W' multi-value data. The C''M''Y''K''O''G''V''W'' conversion unit 302 converts the R'G'B'W' multi-value data into data corresponding to the ink color of the recording head 22, and generates multi-value C''M''Y''K''O''G''V''W'' data. The shading unit 303 performs processing to correct streaks and white streaks caused by uneven density caused by variations in the amount of ink droplets ejected by the nozzles of the recording head 22 and defective nozzle ejection conditions, and generates multi-value C''''M''''Y''''K''''O''''G''''V''''W'''' data.

[0044] In order to perform correction processing for streaks and white streaks caused by uneven density, it is necessary to obtain information on the ejection state of each nozzle in advance, such as information on whether or not there is an ejection defect in each nozzle and information on the variation in the amount of ink ejected from each nozzle. There are various methods for obtaining this information, as described below. However, when adopting a method based on the results of printing an ejection state detection chart at regular intervals by the recording head 22 and reading the chart image by the scanner unit 11 provided downstream of the recording head 22, attention must be paid to the input image data and the color of the recording medium used when printing the chart.

[0045] For example, if image data that generates W' data is input when a white recording medium is set, when an ejection state detection chart is printed to obtain information on the ejection state of each nozzle of the recording head 22 equipped with W ink, the density difference between the recording medium and the ejection state detection chart cannot be read by the scanner, and there is a risk that the information on the ejection state cannot be obtained properly. Therefore, it is necessary to obtain information on whether the currently set recording medium is white or not. There is no restriction on the means of obtaining the information, and for example, the color of the recording medium may be read using the scanner unit 11. It may be determined based on the information on the recording medium input by the user. It is desirable to take some kind of action based on the obtained information. For example, it may be notified that there is a risk that appropriate shading cannot be performed for the W ink.

[0046] A known method can be used for the correction process on the C''M''Y''K''O''G''V'' data in the shading unit 303. However, when adopting a method of acquiring information on the ejection state of each nozzle based on the results of printing an ejection state detection chart with the recording head 22 and reading the chart image with the scanner unit 11, there are two points to note that are specific to W ink.

[0047] The first point is that a white recording medium cannot be used. This is because, as mentioned above, even if W ink is printed on a white recording medium, the scanner unit cannot read the density difference between the recording medium and the chart image, and there is a risk that information on the ejection state cannot be properly obtained. Therefore, when printing a chart image with W ink, it is necessary to use a recording medium other than white, such as black.

[0048] The second point is that the handling of the information obtained based on the results of scanning by the scanner unit 11 must be different from that of CMYKOGV inks. Scanners usually read pixel values ​​in RGB values. A specific example will be described below using as an example printing a solid image with a uniform amount of ink applied.

[0049] When using CMYKOGV inks, if a part where more ink has been applied than the surrounding area, in other words, a part that appears darker, is scanned and the scanned image is obtained, the pixel value of the scanned image expressed in RGB will be low. On the other hand, if a part where less ink has been applied than the surrounding area, in other words, a part that appears lighter, is scanned and the scanned image is obtained, the pixel value of the scanned image will be high. Therefore, by reducing the amount of ink applied to parts with low pixel values ​​and increasing the amount of ink applied to parts with high pixel values, it is possible to adjust the image to a uniform solid color.

[0050] In contrast, when W ink is used in an area where the amount of ink applied is greater than the surrounding area, in other words, an area that appears darker, and the scanned image is obtained, the pixel value of the scanned image expressed in RGB will be high. On the other hand, when W ink is used in an area where the amount of ink applied is less than the surrounding area, in other words, an area that appears lighter, and the scanned image is obtained, the pixel value of the scanned image will be low. Therefore, by performing the opposite process to CMYKOGV inks, which is to increase the amount of ink applied to areas with low pixel values ​​and decrease the amount of ink applied to areas with high pixel values, it is possible to adjust the image to a uniform solid color.

[0051] The above conversion processes are performed using lookup tables corresponding to the respective processes.

[0052] The quantization unit 304 quantizes the C'''M''''Y''''K''''O''''G''''V''''W'''' data to generate quantized data C''''M''''Y''''K''''O''''G''''V''''W''''. Error diffusion is used as the quantization process. There are no particular limitations on the quantization process, and dithering or the like may also be used. In the printing device 1 of this embodiment, the generated quantized data C''''M''''Y''''K''''O''''G''''V'''' is 1-bit binary data for each of CMYKOGV. A pixel with quantization data of 0 indicates no ink ejection, and a pixel with quantization data of 1 indicates ink ejection, and the print head 22 ejects ink based on the quantized data.

[0053] A user sets sheet S, which is a continuous sheet-like recording medium wound in a roll, in unwinding roll section 2. When recording device 1 is first installed, it is necessary to guide sheet S into recording device 1, but when adding or replacing recording media, it is preferable to add more sheet S and set it.

[0054] After the user has finished setting the recording medium (sheet S), he or she registers information about the recording medium in the recording device 1. From this information, the operating parameters of the transport unit, drying unit, cooling unit, etc. are determined directly or indirectly. If the recording device 1 has not handled the recording medium before, the user may be notified to adjust the recording head, etc.

[0055] The recording device 1 of this embodiment acquires information on the discharge state of each nozzle before performing image processing including image quality adjustment by shading for actual printing. The information on the discharge state includes information on whether or not the nozzle has a discharge defect, information on the variation in the amount of ink discharged from each nozzle, and the like. At this time, a known method can be used to acquire the information on the discharge state. For example, in the case of an inkjet method using a heating element, the discharge state of the nozzle may be detected by determining the presence or absence of an inflection point in a temperature change curve after applying a driving voltage for discharging ink. Alternatively, a discharge state detection chart may be printed at regular intervals by the recording head 22, and the discharge state may be detected based on the result of reading the chart image by the scanner unit 11 provided downstream of the recording head 22. The information on the discharge state of each nozzle detected in this way (the inspection result of the discharge state of each nozzle) is stored in the storage device 35 in the control unit 31. Note that the information may be stored in a storage area provided in the recording head 22, or may be stored in an external storage device (USB memory, etc.) connected to the recording device 1. Hereinafter, the information on the discharge state immediately before the image processing including image quality adjustment by shading is referred to as discharge state information A.

[0056] In general, in inkjet recording devices, the amount of ink droplets ejected from each nozzle may vary due to manufacturing errors, etc. If the amount of ink droplets is large, the density of the recorded image will be high, and if the amount of ink droplets is small, the density of the recorded image will be low. Furthermore, if a nozzle is in an ejection failure state, there is a concern that the accuracy of the position where the ejected ink droplets land on the recording medium will decrease, or that ink droplets will not be ejected. Therefore, there is a risk that image defects such as streaks and white streaks due to uneven density will occur due to these factors.

[0057] Shading is performed as a process for reducing such image defects. Known techniques may be used for shading. For example, if there is a nozzle with a small ejection volume, the density data of the image in the area printed by that nozzle and the density of some pixels of the nozzles adjacent to that nozzle may be reduced, and the reduced image density data may be added to the density data of the pixels of other nozzles printing the same line. Alternatively, the number or size of the ink dots finally formed may be increased or decreased depending on information related to the ejection volume of each nozzle.

[0058] In actual printing, the user performs a test print after image processing including image quality adjustment by shading, and if the user determines that the image quality of the recorded image is good, inputs print data for actual printing. At this time, the print data may include an instruction to change the operating parameters registered in the recording device 1. After receiving the print data, the recording device 1 transports the recording medium (sheet S) and drives the recording head 22. When the recording medium reaches the desired transport speed, the recording device 1 starts a print operation to output the image input by the user (step S102 in FIG. 8).

[0059] Next, a discharge failure monitoring function performed by the recording apparatus 1 will be described with reference to a flowchart. The discharge failure monitoring function is a function for detecting discharge failures that occur during a printing operation. Fig. 8 is a flowchart showing a period during which discharge failure monitoring is performed.

[0060] When the print data is received, the host device 33 instructs the start of the print operation, and the print operation is started (S101, S102). Then, in parallel with the print operation that starts after the recording device 1 receives the print data, the recording device 1 performs discharge defect monitoring (S103).

[0061] 9 is a flowchart showing the operation of the discharge failure monitoring process. This operation is realized by the CPU 34 executing a control program stored in the storage device 35.

[0062] First, in step S201, the CPU 34 acquires the ejection state information A stored in the storage device 35 in the control unit 31 in advance.

[0063] In step S202, the CPU 34 acquires nozzle ejection state information that changes from moment to moment during a printing operation. Here, the means for acquiring the ejection state information is not particularly limited, and any known method may be used.

[0064] For example, in the case of an inkjet method using a heating element, the nozzle ejection state may be detected by determining the presence or absence of an inflection point in a temperature change curve after applying a driving voltage for ejecting ink, as disclosed in JP 2008-000914 A. Alternatively, as disclosed in JP 2013-252691 A, an ejection state detection chart may be printed at regular intervals by the recording head 22, and the ejection state of the nozzle may be detected based on the result of reading the chart image by the scanner unit 11 provided downstream of the recording head 22. Note that when using the above-mentioned method, the ejection state of each nozzle is generally acquired sequentially. Therefore, it may take time to acquire the ejection state information of all the nozzles. Therefore, in such a case, instead of acquiring the ejection state information of all the nozzles, the nozzles for which the ejection state information needs to be acquired may be selected according to the input print data.

[0065] In step S203, the CPU 34 determines whether the discharge status information acquired in step S202 is the first discharge status information acquired after the start of the printing operation. If the discharge status information is the first discharge status information acquired after the start of the printing operation, the CPU 34 proceeds to step S204, otherwise, the CPU 34 proceeds to step S205.

[0066] In step S204, the CPU 34 stores the ejection status information acquired in step S202 in the storage device 35. Hereinafter, the ejection status information acquired and stored for the first time after the start of the printing operation is described as ejection status information B. In addition, the ejection status information acquired for the second time or later after the start of the printing operation is described as ejection status information C.

[0067] In step S205, the CPU 34 determines whether there is a difference in the ejection state between before image quality adjustment and the current state based on the ejection state information A, the ejection state information B and the ejection state information C acquired in step S202. If the CPU 34 determines that there is a difference, it determines that the ejection state is NG, proceeds to step S206 for processing. Otherwise, it sets the ejection state as OK and returns the processing to step S202.

[0068] Here, the determination criteria used for the OK / NG determination of the ejection state used in step S205 will be described.

[0069] <OK / NG determination criterion 1> It is conceivable that the ejection state of the recording head 22 deteriorates compared to the state where the user determines that printing is possible with good image quality. As a countermeasure for such a case, when comparing the ejection state information A with the ejection state information acquired after the start of the printing operation, if the number of non-ejecting nozzles has increased, it is determined as NG. Note that a threshold value for the allowable increase in the number of non-ejecting nozzles may be defined, and if it exceeds that threshold value, it may be determined as NG. The ejection state information A is the state of the nozzles for which it is assumed that the user has determined that the image quality is good after performing image processing including shading on the nozzles in that state. Therefore, by comparing the current ejection state information with the ejection state information A, a comparison is made between the state where the user determines that the image quality is good after shading and the current state, so that an appropriate OK / NG determination of the ejection state can be made.

[0070] <OK / NG determination criterion 2> When performing shading, it may be necessary to determine whether the nozzle that has increased the discharge amount or the nozzle that has decreased the discharge amount has become non-discharging to determine whether the discharge state is OK or NG. As a countermeasure for such a case, for example, among the nozzles (8 nozzles per color in this embodiment) that record the same line, if the number of non-discharging nozzles exceeds 1 for the nozzles that have had the discharge amount increased, it is determined as NG. Also, for the nozzles that have had the discharge amount decreased, if the number of non-discharging nozzles exceeds 3, it is determined as NG. Note that there are no particular restrictions on each threshold value, and any value may be used. Thereby, an appropriate OK / NG determination corresponding to the nozzles corrected after shading can be made.

[0071] <OK / NG Judgment Criterion 3> Without having to compare with the discharge state information A, it is conceivable that the recording head 22 cannot record a printed matter with good image quality. As a countermeasure for such a case, in the discharge state information B and the discharge state information C, if there are non-discharging nozzles equal to or more than a predetermined threshold number, it is determined as NG. In this case, since it is not necessary to compare with the discharge state information acquired in advance, a quick determination is possible, and the number of failed printed matters can be minimized as much as possible.

[0072] <OK / NG Judgment Criterion 4> Even if the discharge state is good at the start of the printing operation, it is conceivable that the discharge state deteriorates during the continuation of the printing operation. As a countermeasure for such a case, by comparing the discharge state information B and the discharge state information C, if the number of non-discharging nozzles has increased, it is determined as NG. Note that a threshold value for the allowable increase in the number of non-discharging nozzles may be determined, and if it exceeds that threshold value, it may be determined as NG.

[0073] <OK / NG Judgment Criterion 5> Even when the number of non-ejecting nozzles is equal, the influence on image quality differs depending on whether the non-ejecting nozzles are dispersed or concentrated. Therefore, there may be a case where it is necessary to determine that non-ejecting nozzles are concentrated in a specific area. As already explained, FIG. 3 shows a partial area (area for 8 nozzles per column) of one chip 221. As shown by the dashed line in FIG. 3, an area formed by dividing the nozzles into segments of 4 nozzles each in a direction perpendicular to the conveyance direction is defined as one segment. Note that there are no particular restrictions on the definition of the segment, and the division may be performed for any number of nozzles, or the division may be performed based on any resolution. In response to the above case, within one of these divided segments, if there are a number of non-ejecting nozzles equal to or more than a predetermined threshold, it is determined as NG. As a result, it becomes possible to handle cases where non-ejecting nozzles are concentrated in a specific area, which cannot be handled by a determination based simply on the number of non-ejecting nozzles.

[0074] <OK / NG Judgment Criteria 6> Since the image quality required for the printed matter may vary depending on the user, for the purpose of making the OK / NG judgment criteria stricter, among the above OK / NG judgment criteria, if any 2 to 5 NG judgment criteria are satisfied, it is determined as NG.

[0075] As described above, regarding the ejection state information B and ejection state information C used when making the OK / NG judgment, instead of acquiring the ejection state information of all nozzles, the nozzles for which it is necessary to acquire the ejection state information may be selected and acquired according to the input printed data. In this case, for the nozzles determined not to require acquisition of the ejection state information, it may be regarded as having no change from the ejection state information A.

[0076] Finally, in step S206, the CPU 34 determines that the recording head 22 is in a state of ejection failure, and the ejection failure monitoring process ends.

[0077] Here, some operation may be performed using the judgment in step S206 as a trigger. For example, a notice may be issued to prompt the user to check the printed matter so that the user can check the printed matter. In addition, since it is considered that the printed matter has poor image quality, the printing operation may be stopped in order to reduce paper waste. Alternatively, in addition to stopping the printing operation, a maintenance operation such as wiping the recording head 22 may be performed in order to remove mist or foreign matter adhering to the recording head 22. Alternatively, in order to reduce the user's operational effort, printing of the input print data may be retried. At this time, printing may be retried for all the number of prints desired by the user, or printing may be retried for the number of prints obtained by subtracting the number of prints recorded before the NG judgment was made from the number of prints desired by the user.

[0078] As described above, according to the above embodiment, it is possible to appropriately determine whether a recorded image is of appropriate image quality as a printed matter, and to provide a printed matter of appropriate image quality to the user.

[0079] Second embodiment In this embodiment, an example of a printing apparatus having a discharge failure compensation function as an image quality adjustment function in addition to shading will be described. The overall configuration of the printing apparatus is similar to that of the first embodiment, so a description thereof will be omitted.

[0080] As described in the first embodiment, the scanner unit 11 is a unit for reading an image formed on the sheet S by the recording unit 7 during printing, and changing the operating conditions of the recording head 22 using the analyzed parameters, and is used for performing shading. In addition, it can also be used to detect abnormalities in the recording elements and change the operation of the recording device 1. That is, if only a small number of recording elements are determined to be abnormal, it can be used to perform so-called non-discharge complementation, in which recording is substituted by the surrounding recording elements. By performing non-discharge complementation, it is possible to increase the possibility of good recording of the printed matter, and it is expected that the life of the recording head 22 will be extended.

[0081] FIG. 10 is a diagram showing the flow of image processing performed by the image processing unit 36 ​​provided in the control unit 31 in the second embodiment.

[0082] In the recording device 1 of this embodiment, RGBW multi-value data is input from the host device 33 to the control unit 31 based on image data input by the user to the operation unit 32. The RGBW conversion unit 301 converts the input RGBW data into data suitable for color reproduction by the recording device, and generates R'G'B'W' multi-value data.

[0083] The C''M''Y''K''O''G''V''W'' conversion unit 302 converts the R'G'B'W' multi-value data into data corresponding to the ink color of the recording head 22, generating multi-value C''M''Y''K''O''G''V''W'' data.

[0084] The shading unit 303 performs processing to correct streaks and white streaks caused by uneven density due to variations in the amount of ink droplets ejected by the nozzles of the recording head 22 and poor nozzle ejection conditions, and generates multi-value C''M''Y''K''O''G''V''W'' data.

[0085] In order to perform correction processing for streaks and white streaks caused by uneven density, it is necessary to obtain information on the ejection state of each nozzle in advance, such as information on whether or not there is an ejection defect in each nozzle and information on the variation in the amount of ink ejected from each nozzle. There are various methods for obtaining this information, as described below. However, when adopting a method based on the results of printing an ejection state detection chart at regular intervals by the recording head 22 and reading the chart image by the scanner unit 11 provided downstream of the recording head 22, attention must be paid to the input image data and the color of the recording medium used when printing the chart.

[0086] For example, if image data that generates W' data is input when a white recording medium is set, when an ejection state detection chart is printed to obtain information on the ejection state of each nozzle of the recording head 22 equipped with W ink, the density difference between the recording medium and the ejection state detection chart cannot be read by the scanner, and there is a risk that the information on the ejection state cannot be obtained properly. Therefore, it is necessary to obtain information on whether the currently set recording medium is white or not. There is no restriction on the means of obtaining the information, and for example, the color of the recording medium may be read using the scanner unit 11. It may be determined based on the information on the recording medium input by the user. It is desirable to take some kind of action based on the obtained information. For example, it may be notified that there is a risk that appropriate shading cannot be performed for the W ink.

[0087] A known method can be used for the correction process on the C''M''Y''K''O''G''V'' data in the shading unit 303. However, when adopting a method of acquiring information on the ejection state of each nozzle based on the results of printing an ejection state detection chart with the recording head 22 and reading the chart image with the scanner unit 11, there are two points to note that are specific to W ink.

[0088] The first point is that a white recording medium cannot be used. This is because, as mentioned above, even if W ink is printed on a white recording medium, the scanner unit cannot read the density difference between the recording medium and the chart image, and there is a risk that information on the ejection state cannot be properly obtained. Therefore, when printing a chart image with W ink, it is necessary to use a recording medium other than white, such as black.

[0089] The second point is that the handling of the information obtained based on the results of scanning by the scanner unit 11 must be different from that of CMYKOGV inks. Scanners usually read pixel values ​​in RGB values. A specific example will be described below using as an example printing a solid image with a uniform amount of ink applied.

[0090] When using CMYKOGV inks, if a part where more ink has been applied than the surrounding area, in other words, a part that appears darker, is scanned and the scanned image is obtained, the pixel value of the scanned image expressed in RGB will be low. On the other hand, if a part where less ink has been applied than the surrounding area, in other words, a part that appears lighter, is scanned and the scanned image is obtained, the pixel value of the scanned image will be high. Therefore, by reducing the amount of ink applied to parts with low pixel values ​​and increasing the amount of ink applied to parts with high pixel values, it is possible to adjust the image to a uniform solid color.

[0091] In contrast, when W ink is used in an area where the amount of ink applied is greater than the surrounding area, in other words, an area that appears darker, and the scanned image is obtained, the pixel value of the scanned image expressed in RGB will be high. On the other hand, when W ink is used in an area where the amount of ink applied is less than the surrounding area, in other words, an area that appears lighter, and the scanned image is obtained, the pixel value of the scanned image will be low. Therefore, by performing the opposite process to CMYKOGV inks, which is to increase the amount of ink applied to areas with low pixel values ​​and decrease the amount of ink applied to areas with high pixel values, it is possible to adjust the image to a uniform solid color.

[0092] The above conversion processes are performed using lookup tables corresponding to the respective processes.

[0093] The quantization unit 304 quantizes the C'''M''''Y''''K''''O''''G''''V''''W'''' data to generate quantized data C''''M''''Y''''K''''O''''G''''V''''W''''. Error diffusion or the like is used as the quantization process. The discharge failure complementation unit 305 performs discharge failure complementation processing as described below based on the C''''M''''Y''''K''''O''''G''''V''''W'''' data to generate quantized data C''''''M''''''Y''''''K''''''O''''''G''''''V''''''W''''''. In the recording apparatus 1, the generated quantized data C''''''M''''''Y''''''K''''''O''''''G''''''V''''''W'''''' is 1-bit binary data for each of CMYKOGV. A pixel with quantized data of 0 represents no ink ejection, and a pixel with quantized data of 1 represents ink ejection, and the recording head 22 ejects ink based on the quantized data.

[0094] As in the first embodiment, the recording device of this embodiment acquires ejection status information for each nozzle before performing image processing including image quality adjustment by shading and non-ejection compensation for actual printing. The acquired ejection status information is stored in a storage device 35 in the control unit 31. The information may be stored in a storage area provided in the recording head 22, or may be stored in an external storage device (such as a USB memory) connected to the recording device 1.

[0095] Figure 11 is a diagram showing a group of nozzles (in this embodiment, a total of eight nozzles from nozzle rows A to H) that print the same line, where black circles represent nozzles that eject ink and white circles represent nozzles that do not eject ink.

[0096] As shown in Figure 11(a), when a nozzle determined to have an ejection defect (a non-ejecting nozzle) such as nozzle row B is designated as the nozzle that will eject ink, the non-ejection is complemented by allocating printing data to another nozzle (in this embodiment, nozzle row C) that has not been determined to have an ejection defect and is capable of printing the same line, as shown in Figure 11(b).

[0097] In actual printing, after performing image processing including non-ejection compensation and image quality adjustment by shading, when the user performs test printing and determines that the image quality of the recorded image is good, the user inputs the print data for actual printing. At this time, the print data may include an instruction to change the operation parameters registered in the recording apparatus 1. After receiving the print data, the recording apparatus 1 conveys the recording medium (sheet S) and drives the recording head 22. When the recording medium reaches the desired conveyance speed, the recording apparatus 1 starts the printing operation of outputting the image input by the user (step S102 in FIG. 8).

[0098] Thereafter, in the same manner as in the first embodiment, monitoring for ejection failure is performed according to the flowcharts of FIGS. 8 and 9. Here, with the introduction of the non-ejection compensation function, the following may be added as the OK / NG determination criteria for the ejection state of the recording head 22 in step S205 of FIG. 9.

[0099] <OK / NG determination criterion 7> As an alternative to the nozzle determined to have an ejection failure, when the nozzle to which the recording data for the non-ejection compensation is allocated becomes a non-ejection nozzle, it is determined as NG.

[0100] <OK / NG determination criterion 8> Since the image quality required for the printed matter may vary depending on the user, for the purpose of making the OK / NG determination criteria stricter, when any 2 to 6 of the above OK / NG determination criteria excluding the OK / NG determination criterion 6 are satisfied, it is determined as NG.

[0101] In the present embodiment, since non-ejection compensation is performed in addition to the processing of the first embodiment, the possibility of recording the printed matter well can be further enhanced. In addition, it can also be expected to further extend the life of the recording head 22.

[0102] The disclosure of this specification includes the following recording apparatus, its control method, program, and storage medium.

[0103] (Item 1) an inspection means for inspecting the ejection state of a plurality of nozzles of a recording head having the plurality of nozzles for ejecting liquid; a correction means for correcting the ejection state of the plurality of nozzles based on the inspection result by the inspection means; a first determination means for determining whether or not a defect has occurred in the print head based on a difference between a discharge state of the plurality of nozzles immediately before the discharge state is corrected and a discharge state of the plurality of nozzles during a printing operation; A recording device comprising:

[0104] (Item 2) The recording device described in item 1, characterized in that the inspection means causes the recording head to record an inspection pattern for inspecting the ejection state of the nozzles on a recording medium, and inspects the ejection state of the nozzles by reading the recorded inspection pattern.

[0105] (Item 3) The recording device described in item 1 or 2, characterized in that the inspection means inspects the ejection state of the nozzle by determining whether or not there is an inflection point in a temperature change curve after applying a drive voltage for ejecting liquid to the recording head.

[0106] (Item 4) 4. The recording apparatus according to any one of items 1 to 3, further comprising a second determination unit that determines whether or not a defect has occurred in the recording head based on the ejection state of the plurality of nozzles during the recording operation.

[0107] (Item 5) 5. The recording apparatus according to any one of items 1 to 4, wherein the inspection means inspects the variation in the amount of liquid ejected from each nozzle as the ejection state of the plurality of nozzles.

[0108] (Item 6) 6. The recording apparatus according to item 5, wherein the correction means corrects variations in the amount of liquid ejected from each nozzle.

[0109] (Item 7) 5. The recording apparatus according to any one of items 1 to 4, wherein the inspection means inspects nozzle ejection defects as the ejection states of the plurality of nozzles.

[0110] (Item 8) 8. The recording apparatus according to item 7, further comprising a complementing unit that drives the recording head so that ejection failure of the nozzle is complemented by other nozzles.

[0111] (Item 9) 9. The recording apparatus according to any one of items 1 to 8, further comprising a notification unit that notifies a user of a defect in the recording head when the defect occurs in the recording head.

[0112] (Item 10) 10. The recording apparatus according to any one of items 1 to 9, further comprising a unit for stopping a recording operation when a defect occurs in the recording head.

[0113] (Item 11) 11. The recording apparatus according to any one of items 1 to 10, further comprising a maintenance unit that performs a maintenance operation on the recording head when a defect occurs in the recording head.

[0114] (Item 12) an inspection step of inspecting the ejection state of a plurality of nozzles of a recording head having the plurality of nozzles for ejecting liquid; a correction step of correcting the ejection states of the plurality of nozzles based on the inspection results in the inspection step; a first determination step of determining whether or not a defect has occurred in the print head based on a difference between a discharge state of the plurality of nozzles immediately before the discharge state is corrected and a discharge state of the plurality of nozzles during a printing operation; 13. A method for controlling a recording apparatus comprising the steps of:

[0115] (Item 13) Item 13. A program for causing a computer to execute each step of the control method according to item 12.

[0116] (Item 14) A computer-readable storage medium storing a program for causing a computer to execute each step of the control method described in item 12.

[0117] (Other embodiments) The present invention can also be realized by a process in which a program for realizing one or more functions of the above-mentioned embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for realizing one or more functions.

[0118] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0119] 1: recording device, 2: unwinding roll section, 4: first main transport section, 7: recording section, 10: recorded image position detection section, 11: scanner section, 12: second main transport section, 14: take-up roll section, 22: recording head, 31: control section, 34: CPU, 35: storage device, 36: image processing section, 40: drying section, 50: cooling section, S: sheet

Claims

1. an inspection means for inspecting the ejection state of a plurality of nozzles of a recording head having the plurality of nozzles for ejecting liquid; a correction means for correcting the ejection state of the plurality of nozzles based on the inspection result by the inspection means; a first determination means for determining whether or not a defect has occurred in the print head based on a difference between a discharge state of the plurality of nozzles immediately before the discharge state of the plurality of nozzles is corrected and a discharge state of the plurality of nozzles during a printing operation; A recording device comprising:

2. 2. The recording apparatus according to claim 1, wherein the inspection means inspects the ejection state of the nozzles by recording an inspection pattern for inspecting the ejection state of the nozzles on a recording medium using the recording head and reading the recorded inspection pattern.

3. 2. The recording apparatus according to claim 1, wherein the inspection means inspects the ejection state of the nozzles by determining whether or not there is an inflection point in a temperature change curve after a drive voltage for ejecting liquid from the recording head is applied.

4. 2. The printing apparatus according to claim 1, further comprising a second determination unit that determines whether or not a defect has occurred in the print head based on the ejection state of the plurality of nozzles during the printing operation.

5. 2. The recording apparatus according to claim 1, wherein the inspection means inspects the variation in the amount of liquid ejected from each nozzle as the ejection state of the plurality of nozzles.

6. 6. The recording apparatus according to claim 5, wherein the correction means corrects variations in the amount of liquid ejected from each nozzle.

7. 2. The recording apparatus according to claim 1, wherein said inspection means inspects for nozzle ejection defects as the ejection states of said plurality of nozzles.

8. 8. The printing apparatus according to claim 7, further comprising a complementing unit that drives the printhead so that a discharge failure of the nozzle is complemented by other nozzles.

9. 2. The recording apparatus according to claim 1, further comprising: a notifying unit that notifies a user of a defect in the recording head when the defect occurs in the recording head.

10. 2. The recording apparatus according to claim 1, further comprising a means for stopping a recording operation when a defect occurs in the recording head.

11. 2. The recording apparatus according to claim 1, further comprising a maintenance unit that performs a maintenance operation on the recording head when a defect occurs in the recording head.

12. an inspection step of inspecting the ejection state of a plurality of nozzles of a recording head having the plurality of nozzles for ejecting liquid; a correction step of correcting the ejection state of the plurality of nozzles based on the inspection result in the inspection step; a first determination step of determining whether or not a defect has occurred in the print head based on a difference between a discharge state of the plurality of nozzles immediately before the discharge state of the plurality of nozzles is corrected and a discharge state of the plurality of nozzles during a printing operation; 13. A method for controlling a recording apparatus comprising the steps of:

13. A program for causing a computer to execute each step of the control method according to claim 12.

14. A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to claim 12.

Images