Patent Application
20240092078
The present invention relates to a printing apparatus including an ink ejection head (print head) provided with many nozzles for ejecting ink, and a printing method using the printing apparatus.
Conventionally, an inkjet-type printing apparatus (hereinafter simply referred to as an “inkjet printing apparatus”) that performs printing by ejecting ink onto base material (printing paper, etc.) is known. In an inkjet printing apparatus, printing is generally performed using aqueous ink. However, in recent years, for example, for label printing, the development of an inkjet printing apparatus that performs printing using ultraviolet (UV) ink (ultraviolet curable ink) has been advanced. In the inkjet printing apparatus using UV ink, the UV ink is irradiated with ultraviolet rays (UV light) in order to fix the UV ink ejected from the ink ejection head to the base material.
With respect to the inkjet printing apparatus, there are individual differences in the nozzles provided in the ink ejection head. For this reason, even when the ink is ejected from many nozzles provided in the ink ejection head based on the same drive signal, the amount of ink ejected from each of those many nozzles varies. When printing is performed in such a state, high-quality printed matter cannot be obtained. Therefore, density uniformity correction that corrects the density of the print data such that the ink is ejected from each of all the nozzles in the same manner is performed.
In the inkjet printing apparatus, ink ejection failure may occur due to the solidification of the ink caused by non-use over a long period of time, or other reasons. When ink ejection failure occurs, the lacking of a dot corresponding to a nozzle in an ejection failure state (hereinafter referred to as a “defective nozzle”), that is, dot missing, occurs in the printed image. Therefore, nozzle-defect correction that corrects the density of the print data such that the ink to be ejected from the defective nozzle is ejected from another nozzle (typically, a nozzle adjacent to the defective nozzle) is performed. Note that Japanese Laid-Open Patent Publication No. 2014-188785 discloses an example of nozzle-defect correction.
With reference to
By the density uniformity correction and nozzle-defect correction as described above, the occurrence of unevenness in the printed image due to the individual difference among the nozzles and the presence of the defective nozzle is prevented.
However, in the case of the occurrence of the defective nozzle, even when an amount of ink to be ejected from the defective nozzle is ejected from another nozzle by performing nozzle-defect correction, printed matter with a defect suitably eliminated may not be obtained. In particular, when a defect occurs in a nozzle corresponding to an area where single-color high-density printing is performed, the dot size of the ink ejected from another nozzle tends to be insufficient to eliminate the defect. Thus, depending on the image to be printed, printed matter of sufficient quality cannot be obtained by the conventional nozzle-defect correction.
An ink ejection head generally includes a plurality of head modules, and color unevenness may occur in an area where there is overlap between an area where the ink is ejected by one head module and an area where the ink is ejected by its adjacent head nozzle. Moreover, there is a strong demand from a user to improve the print quality of a so-called solid image.
In view of the above circumstances, an object of the present invention is to achieve an inkjet printing apparatus (a printing apparatus that performs printing by ejecting ink onto a printing medium) capable of improving the quality of printed matter.
One aspect of the present invention is directed to a printing apparatus that performs printing by ejecting ink onto a printing medium, the printing apparatus including:
With such a configuration, the printing apparatus is provided with the first ink ejection head that ejects the first ink and the second ink ejection head that is disposed on the upstream side of the first ink ejection head regarding the conveyance direction of the printing medium and ejects the second ink. When printing is performed for the correction area determined by the correction area determination unit, the second ink is ejected before the first ink is ejected. Here, the wet spreading range of the first ink on the printing medium is larger when the first ink is ejected onto the second ink that is ejected onto the printing medium than when the first ink is directly ejected onto the printing medium. Therefore, in the correction area, the dot size of the first ink is larger than originally intended. Therefore, for example, by defining an area corresponding to a defective nozzle, an area where there is overlap between an area where the ink is ejected by one ink ejection head and an area where the ink is ejected by its adjacent ink ejection head, an area where a solid image is printed, or some other area as the correction area, it is possible to improve the print quality compared to the related art. Thus, a printing apparatus (a printing apparatus that performs printing by ejecting the ink onto a printing medium) capable of improving the quality of printed matter is achieved.
Another aspect of the present invention is directed to a printing method using a printing apparatus that includes a conveyor configured to convey a printing medium, a first ink ejection head configured to eject a first ink onto the printing medium conveyed by the conveyor, and a second ink ejection head configured to eject a second ink onto the printing medium conveyed by the conveyor, the printing method including:
These and other objects, features, modes, and advantageous effects of the present invention will become more apparent from the following detailed description of the present invention with reference to the accompanying drawings.
Preferred embodiments of the present invention will be described below with reference to the drawings.
Meanwhile, in the present embodiment, an inspection chart for inspecting the state of the nozzles in the ink ejection head is printed before printing for obtaining desired printed matter is performed. A printed image obtained by printing the inspection chart is captured by the imaging unit 16, and the imaged data thereby obtained is sent to the print controller 200. Then, in the print controller 200, density correction to be described later is performed based on the imaged data.
Since the base material 12 is conveyed from the lower side to the upper side in
In the present embodiment, a first ink ejection head is achieved by each of the ink ejection head 150(B), the ink ejection head 150(O), the ink ejection head 150(C), the ink ejection head 150(M), the ink ejection head 150(Y), and the ink ejection head 150(K), a second ink ejection head is achieved by the ink ejection head 150(W), a first ultraviolet irradiator is achieved by the UV-LED 159(c), and a second ultraviolet irradiator is achieved by the UV-LED 159(b).
Note that the configuration of the recording unit 15 shown in
In the example shown in
In the following description, when the name of one color is “Z”, a nozzle that ejects a Z ink (a nozzle included in the ink ejection head 150 for Z ink) may be referred to as a “Z ink ejection nozzle”. For example, a nozzle that ejects the cyan ink (a nozzle included in the ink ejection head 150(C) for cyan ink) may be referred to as a “cyan ink ejection nozzle”.
The auxiliary storage device 221 stores a print control program (program for controlling the execution of print processing by the printer body 100) P. The CPU 211 reads a print control program P stored in the auxiliary storage device 221 into the memory 212 and executes the program to achieve various functions of the print controller 200. The memory 212 includes random-access memory (RAM) and read-only memory (ROM). The memory 212 functions as a work area for the CPU 211 to execute the print control program P stored in the auxiliary storage device 221. Note that the print control program P is provided by being stored into the computer-readable recording medium (non-transitory recording medium). That is, for example, the user purchases the optical disc 29 as a recording medium of the print control program P, inserts the optical disc into the optical disc drive 222, reads the print control program P from the optical disc 29, and installs the print control program P in the auxiliary storage device 221.
In the present embodiment, when the nozzle-defect correction described above is performed, processing is performed to correct density data included in print data so that white ink is ejected from a white ink ejection nozzle corresponding to a nozzle adjacent to a defective nozzle (hereinafter, the nozzle adjacent to the defective nozzle is referred to as a “defect adjacent nozzle” for convenience). Hereinafter, this processing is referred to as “white correction”.
In the present embodiment, white correction is performed only for an area where printing is performed with a single-color ink to be ejected from the defective nozzle, the single-color ink having a density equal to or higher than a predetermined value. Therefore, in a case where the defective nozzle is included in the ink ejection head 150(C) for cyan ink as described above, white correction is performed, for example, only for an area where high-density cyan single-color printing is performed, for example, with a density of 80% or more. However, white correction may also be performed for an area where mixed-color printing is performed.
When white correction is performed, in the above example, during printing, first, the white ink is ejected from the white ink ejection nozzle corresponding to the defect adjacent nozzle onto the base material 12. Thereafter, the cyan ink is ejected from the defect adjacent nozzle. That is, in the area where white correction has been performed, as schematically shown in
The wet spreading range of the color ink (in the above example, cyan ink) on the base material 12 is larger when the color ink is ejected onto the white ink that has been ejected onto the base material 12 than when the color ink is directly ejected onto the base material 12. An example of a result of an experiment related to this is shown in
Normally, the white ink is cured by ultraviolet irradiation after being ejected. However, in the present embodiment, the ultraviolet irradiation with the white ink by the UV-LED 159(b) is stopped when the white ink is ejected onto the target area by white correction. By thus stopping the ultraviolet irradiation on the white ink, the wet spreading range of the white ink is increased, and the wet spreading range of the color ink ejected onto the white ink is also increased effectively.
In the inkjet printing apparatus 10 according to the present embodiment, the white correction described above is performed in addition to density uniformity correction and nozzle-defect correction that have been performed conventionally. In the present specification, a series of processing including density uniformity correction, nozzle-defect correction, and white correction is referred to as “density correction”. The print controller 200 executes the print control program P to achieve a density correction processing unit that is a functional component for performing density correction.
The correction factor calculation unit 241 calculates a correction factor 71 for performing density uniformity correction based on imaged data 70 obtained by the imaging unit 16 capturing the printed image of the inspection chart. For example, focusing on a certain nozzle, in a case where the density obtained by ejecting the ink from the nozzle is (4/5) times the original density, the correction factor 71 corresponding to the nozzle is set to 1.25
The defective nozzle detection unit 242 detects a defective nozzle, which is a nozzle in an ejection failure state, from among many nozzles included in the ink ejection head 150 for color ink based on the imaged data 70. Defective nozzle information 72 for specifying a defective nozzle is outputted from the defective nozzle detection unit 242. When no defective nozzle is detected, only density uniformity correction is performed in the first correction processing unit 2481 in the ink ejection control unit 248.
The base material determination unit 243 determines base material to be used for printing as a printing medium based on, for example, set print conditions. Then, base material information 73 for specifying the base material is outputted from the base material determination unit 243.
The print data holding unit 244 temporarily holds print data (data subjected to RIP processing) 74 transmitted from the print data generation apparatus 30. Note that the print data holding unit 244 is achieved by the memory 212 (cf.
The white correction determination unit 245 determines whether to perform white correction based on the defective nozzle information 72, the base material information 73, and the print data 74. Then, a determination result 75 thus obtained is outputted from white correction determination unit 245. In this regard, in the present embodiment, it is determined that white correction is not to be performed when the base material used for printing is other than a white, base material based on the base material information 73. Further, it is determined, based on the defective nozzle information 72 and the print data 74, that white correction is to be performed when a defective nozzle is present, and an area where the ink is ejected from the defective nozzle and its neighboring nozzle includes an area where single-color high-density printing is performed using the color ink to be ejected from the defective nozzle. In other words, even when the defective nozzle is present, it is determined that white correction is not to be performed unless an area where the ink is ejected from the defective nozzle and its neighboring nozzle includes an area where single-color high-density printing is performed using the color ink to be ejected from the defective nozzle. In this way, white correction is performed only for an area where unevenness caused by the presence of a defective nozzle is noticeable, thereby reducing unnecessary consumption of white ink.
When the determination result 75 outputted from the white correction determination unit 245 indicates that white correction is to be performed, the correction target nozzle specification unit 246 specifies a nozzle (hereinafter referred to as a “correction target nozzle”) that ejects white ink for white correction from among many nozzles included in the ink ejection head 150(W) for white ink based on the defective nozzle information 72 and the print data 74. Then, the correction target nozzle information 76 for specifying the correction target nozzle is outputted from the correction target nozzle specification unit 246.
Meanwhile, in the present embodiment, a template that defines a pattern with which the white ink is ejected onto the pixel portion in the print area by white correction is prepared, and the correction target nozzle specification unit 246 and the correction pattern creation unit 247 refer to the template. For example, a template as shown in
The correction pattern creation unit 247 creates a correction pattern 77 representing a pattern in the entire print area as shown in the template, based on the correction target nozzle information 76 and the print data 74. In the present embodiment, an area where the white ink is to be ejected based on the correction pattern 77 is treated as a correction area. Therefore, creating the correction pattern 77 corresponds to determining the correction area.
As described above, in the present embodiment, white correction is performed only for the area where single-color high-density printing is performed. Here, it is assumed, for example, that a defect has occurred in a cyan ink ejection nozzle that ejects ink in the dotted line portion denoted by reference numeral 57 in
The ink ejection control unit 248 corrects the density data included in the print data 74 and controls the ejection of the ink from each ink ejection head 150 based on corrected density data 78. As described above, the ink ejection control unit 248 includes the first correction processing unit 2481 and the second correction processing unit 2482. When the determination result 75 outputted from the white correction determination unit 245 indicates that white correction is not to be performed, the processing of correcting the density data included in the print data 74 is performed by the first correction processing unit 2481, and when the determination result 75 indicates that white correction is to be performed, the processing of correcting the density data included in the print data 74 is performed by the second correction processing unit 2482.
The first correction processing unit 2481 performs density uniformity correction and nozzle-defect correction based on the correction factor 71, the defective nozzle information 72, and the print data 74. As a result, the density data included in the print data 74 is corrected, and the density data 78 for controlling the ejection of the ink from each ink ejection head 150 is generated.
The second correction processing unit 2482 performs density uniformity correction, nozzle-defect correction, and white correction based on the correction factor 71, the defective nozzle information 72, the correction pattern 77, and the print data 74. As a result, the density data included in the print data 74 is corrected, and the density data 78 for controlling the ejection of the ink from each ink ejection head 150 is generated.
Each of the ink ejection heads 150 including the ink ejection head 150(W) for white ink is configured to be able to eject the ink with a plurality of sizes. Specifically, piezoelectric elements are provided corresponding to the respective nozzles in the ink ejection head 150, and the size of the ink ejected from the nozzles can be changed by changing a voltage waveform of a drive signal applied to the piezoelectric elements. In the present embodiment, the density data is corrected by the second correction processing unit 2482 so that the white ink is ejected into the correction area with the smallest size among the plurality of sizes. That is, the ink ejection control unit 248 controls the ejection of the white ink from the ink ejection head 150(W) so that the white ink is ejected into the correction area with the smallest size among the plurality of sizes. This prevents the white ink from being consumed more than necessary in order to widen the wet spreading range of the color ink. However, the white ink may be ejected into the correction area with a size other than the smallest size.
Note that the time from when the color ink is ejected from the ink ejection head 150 onto the base material 12 to when the color ink is cured by ultraviolet irradiation from the UV-LED 159(c) varies for each color of the color inks. Referring to
The UV-LED setting unit 249 controls the ultraviolet irradiation performed by the UV-LED 159(b) for white ink by giving an ultraviolet irradiation control signal 79 to the UV-LED 159(b), based on the determination result 75 outputted from the white correction determination unit 245. Specifically, when the determination result 75 indicates that white correction is to be performed, the UV-LED setting unit 249 stops the ultraviolet irradiation performed by the UV-LED 159(b). Therefore, when white correction is performed, during printing, ultraviolet irradiation from the UV-LED 159(b) is not performed on the white ink ejected from the ink ejection head 150(W) onto the base material 12. When the determination result 75 indicates that white correction is not to be performed, the UV-LED setting unit 249 maintains the ultraviolet irradiation performed by the UV-LED 159(b). Regarding a case where the determination result 75 indicates that white correction is to be performed, the configuration may be such that the UV-LED setting unit 249 reduces the intensity of the ultraviolet irradiation performed by the UV-LED 159(b). That is, if wet spreading range of the color ink becomes sufficiently wide when the color ink is ejected onto the white ink, it is not always necessary to stop the ultraviolet irradiation with the white ink performed by the UV-LED 159(b).
Although the calculation of the correction factor 71 by the correction factor calculation unit 241 and the identification of the defective nozzle by the defective nozzle detection unit 242 are performed based on the imaged data 70 in the present embodiment, the present invention is not limited thereto. In a case where an inkjet printing apparatus 10 that does not include the imaging unit 16 has been adopted, the calculation of the correction factor 71 and the identification of the defective nozzle may be performed by an operator visually checking the printed image of the inspection chart.
In addition, a configuration may be adopted which includes a component to receive an input of the base material information 73 by an operator instead of the base material determination unit 243, and the processing by the white correction determination unit 245 (the processing of determining whether to perform white correction) may be performed based on the base material information 73 received by the component.
In the present embodiment, a correction area determination unit is achieved by the correction pattern creation unit 247, and an ultraviolet irradiation controller is achieved by the UV-LED setting unit 249.
In the above description, it has been described that the template shown in
In a case where the template shown in
Focusing on the conveyance direction of the base material 12 with respect to the pixel portions onto which the white ink is ejected, in a case where the template shown in
Hereinafter, a procedure for density correction in the present embodiment will be described with reference to
After the start of density correction, first, the recording unit 15 prints an inspection chart for inspecting the states of the nozzles in the ink ejection heads 150 for color inks (specifically, the ink ejection head 150(B) for blue ink, the ink ejection head 150(O) for orange ink, the ink ejection head 150(C) for cyan ink, the ink ejection head 150(M) for magenta ink, the ink ejection head 150(Y) for yellow ink, and the ink ejection head 150(K) for black ink) (step S110). Then, the imaging unit 16 captures the printed image obtained by printing the inspection chart (step S112). Thereby, the imaged data 70 is outputted from the imaging unit 16.
Thereafter, the correction factor calculation unit 241 calculates the correction factor 71 for performing density uniformity correction based on the imaged data 70 (step S114). Next, the defective nozzle detection unit 242 detects a defective nozzle among many nozzles included in the ink ejection heads 150 for color inks based on the imaged data 70 (step S116).
After the detection of the defective nozzle, the base material determination unit 243 determines the base material (printing medium) to be used for printing (step S118). Then, the white correction determination unit 245 determines whether the base material used for printing is a white base material (step S120). As a result, when the base material used for printing is a white base material, the processing proceeds to step S121, and when the base material used for printing is not a white base material, the processing proceeds to step S130.
In step S121, the white correction determination unit 245 further determines whether it is necessary to perform white correction based on the print data 74 and the information on the defective nozzle detected in step S116 (the defective nozzle information 72 above). As a result, when it is necessary to perform white correction, the processing proceeds to step S122, and when it is not necessary to perform white correction, the processing proceeds to step S130.
In step S122, the correction target nozzle specification unit 246 specifies the correction target nozzle described above based on the print data 74 and the information on the defective nozzle detected in step S116 (the defective nozzle information 72 above).
Next, the correction pattern creation unit 247 creates the correction pattern 77 described above based on the print data 74 and the information on the correction target nozzle specified in step S122 (step S124) (the correction target nozzle information 76 above). In other words, the correction area, which is a part of area where the white ink is to be ejected for the purpose of widening the wet spreading range of the color ink among the area on the base material 12, is determined.
After the creation of the correction pattern 77, the ultraviolet irradiation from the UV-LED 159(b) for white ink is stopped based on the control by the UV-LED setting unit 249 (step S126). Thus, as described above, when white correction is performed, ultraviolet irradiation from the UV-LED 159(b) is not performed on the white ink ejected from the ink ejection head 150(W) onto the base material 12.
After the ultraviolet irradiation from the UV-LED 159(b) is stopped, the second correction processing unit 2482 performs density uniformity correction, nozzle-defect correction, and white correction based on the correction factor 71 calculated in step S114, the information on the defective nozzle detected in step S116 (the defective nozzle information 72 above), the correction pattern 77 created in step S124, and the print data 74 (step S128).
In step S130, the first correction processing unit 2481 performs density uniformity correction and nozzle-defect correction based on the correction factor 71 calculated in step S114, the information on the defective nozzle detected in step S116 (the defective nozzle information 72 above), and the print data 74.
When the process of step S128 or the process of step S130 ends, density correction ends.
After density correction is performed according to the above procedure, the ink ejection control unit 248 controls the ejection of the ink from each ink ejection head 150 based on the density data 78 obtained by density correction, whereby the actual printing on the base material 12 is performed. At this time, as can be grasped from
According to the present embodiment, when a defective nozzle is detected in the ink ejection head 150 for color ink, for a part of area where single-color high-density printing with the color ink to be ejected from the defective nozzle is performed among the area (an area on the base material 12) where the ink is ejected from the defective nozzle and its neighboring nozzle, white correction that corrects the density data such that the white ink is ejected from the white ink ejection nozzle corresponding to the defect adjacent nozzle is performed. Here, the wet spreading range of the color ink on the base material 12 is larger when the color ink is ejected onto the white ink that has been ejected onto the base material 12 than when the color ink is directly ejected onto the base material 12. Therefore, by ejecting the ink from each ink ejection head 150 based on the density data after white correction, the color ink sufficiently spreads on the base material 12 in the area to be subjected to white correction, and the effect by nozzle-defect correction (the effect of eliminating the defect and preventing the occurrence of unevenness) is enhanced compared to the related art. That is, even when a defect has occurred in the nozzle corresponding to the area where single-color high-density printing is performed, the occurrence of unevenness in the printed image due to the presence of the defective nozzle is prevented effectively. Note that the color of the ink (white ink) used to widen the wet spreading range of the color ink is the same as the color of the base material 12. Therefore, the color of the ink ejected onto the base material 12 to widen the wet spreading range of the color ink is not noticeable on the printed image. As above, according to the present embodiment, the inkjet printing apparatus 10 capable of improving the quality of printed matter is achieved. Since the occurrence of unevenness due to the presence of the defective nozzle is effectively prevented, the necessity of reprinting is reduced compared to the related art, and the consumption of the base material and the ink can be reduced. In this way, it is possible to contribute to the achievement of the sustainable development goals (SDGs).
In the first embodiment, in order to increase the wet spreading range of the color ink on the base material 12 by performing nozzle-defect correction, the white ink has been ejected onto the base material 12 before the ejection of the color ink onto the base material 12 in the target area. However, the present invention is not limited thereto. Therefore, examples of using inks other than the white ink to increase the wet spreading range of the color ink will be described below as modifications of the first embodiment. Note that a first modification and a second modification described here can also be applied to a second embodiment and a third embodiment to be described later.
In the present modification, printing is performed on a transparent base material for a label. Then, a transparent ink is used instead of the white ink in the first embodiment. To achieve this, the ink ejection head 150(E) provided in the recording unit 15 (
Here, it is assumed that the nozzle denoted by reference numeral 511 in
When transparency correction is performed, in the above example, during printing, first, the transparent ink is ejected from the transparent ink ejection nozzles corresponding to the defect adjacent nozzles onto the base material (transparent base material) 12. Thereafter, the cyan ink is ejected from the defect adjacent nozzles. That is, in the area where transparency correction has been performed, as schematically shown in
In the present modification, when a defect occurs in the black ink ejection nozzle, the yellow ink with a higher brightness value than the black ink is ejected onto the base material 12 before the black ink is ejected onto the base material 12 in the target area to enhance the effect of nozzle-defect correction. Further, instead of white correction in the first embodiment, processing is performed to correct the density data such that the yellow ink with a higher brightness value than the black ink is ejected from the ink ejection head 150(Y) to make the wet spreading range of the black ink large (hereinafter, this processing is referred to as “yellow correction”)
Note that the area where the yellow ink is ejected for the purpose of enhancing the effect of nozzle-defect correction is limited to an area other than the area where the yellow ink is ejected to form the printed image. By limiting the area where the yellow ink is ejected in this way, it is possible to prevent the deterioration of the print quality due to the adoption of the yellow ink as the ink to increase the wet spreading range of the black ink.
Here, it is assumed that the nozzle denoted by reference numeral 521 in
When the yellow correction is performed, during printing, first, the yellow ink is ejected from the yellow ink ejection nozzles corresponding to the defect adjacent nozzles onto the base material 12. Thereafter, the black ink is ejected from the defect adjacent nozzles. That is, in the area where the yellow correction has been performed, as schematically shown in
Moreover, as still another example, when a defect occurs in the black ink ejection nozzle, the blue ink with little color difference from the black ink may be ejected onto the base material 12 before the black ink is ejected onto the base material 12 in the target area to enhance the effect of nozzle-defect correction. In such a case, instead of white correction in the first embodiment, processing may be performed to correct the density data such that the blue ink with little color difference from the black ink is ejected from the ink ejection head 150(B) to make the wet spreading range of the black ink large (hereinafter, this processing is referred to as “blue correction”), and the same ejection control as in the case of yellow correction may be performed.
In the present modification, the white ink and the transparent ink are not used. Therefore, even in the inkjet printing apparatus that performs printing using only the process color ink, the occurrence of unevenness in the printed image due to the presence of the defective nozzle for the black ink ejection nozzle can be effectively prevented by adopting the configuration of the present modification.
In general, each of the ink ejection head 150(W) that ejects white ink, the ink ejection head 150(B) that ejects blue ink, the ink ejection head 150(O) that ejects orange ink, the ink ejection head 150(C) that ejects cyan ink, the ink ejection head 150(M) that ejects magenta ink, the ink ejection head 150(Y) that ejects yellow ink, and the ink ejection head 150(K) that ejects black ink constituting the recording unit 15 includes a plurality of ink ejection heads 150. For example, the ink ejection head 150(W), the ink ejection head 150(B), the ink ejection head 150(O), the ink ejection head 150(C), the ink ejection head 150(M), the ink ejection head 150(Y), and the ink ejection head 150(K) are each configured by arranging a plurality of ink ejection heads 150 in a staggered manner as shown in
The overall configuration of the printing system (cf.
Hereinafter, density correction in the present embodiment will be described.
The white correction candidate area acquisition unit 251 obtains a white correction candidate area 81 as a candidate for an area to be subjected to white correction, based on head information 80 including information related to the position of the head module 151 in the ink ejection head 150. In the present embodiment, for example, a head connection area such as an area where the ink is ejected from each of the nozzles included in the portions denoted by reference numerals 66, 67 in
The white correction determination unit 245 determines whether to perform white correction based on the base material information 73, the white correction candidate area 81, and the print data 74. Then, the determination result 75 is outputted from white correction determination unit 245. In this regard, in the present embodiment, similarly to the first embodiment, it is determined that white correction is not to be performed when the base material used for printing is other than a white base material, based on the base material information 73. It is determined that white correction is to be performed when an area where single-color printing is performed is included in the white correction candidate areas 81, based on the white correction candidate area 81 and the print data 74. In this way, white correction is performed only for an area where color unevenness is noticeable, thereby reducing unnecessary consumption of white ink. Although white correction is performed only for an area where the single-color printing is performed in the present embodiment, white correction may also be performed for an area where mixed-color printing is performed.
The correction target nozzle specification unit 246 specifies a correction target nozzle from among many white ink ejection nozzles included in the ink ejection head 150(W) for white ink based on the white correction candidate area 81 and the print data 74 when the determination result 75 outputted from the white correction determination unit 245 indicates that white correction is to be performed. Then, the correction target nozzle information 76 for specifying the correction target nozzle is outputted from the correction target nozzle specification unit 246. Note that the head module portion corresponding to the white correction candidate area 81 includes many nozzles, and hence many white ink ejection nozzles are usually specified as correction target nozzles compared to the first embodiment. Therefore, the correction pattern creation unit 247 creates the correction pattern 77 so that the area to be the ejection target of the white ink (correction area) becomes wider than in the first embodiment.
Meanwhile, in the present embodiment, a plurality of templates are prepared in advance each as a template that is a source of the correction pattern 77, and a template to be adopted is determined based on a printing rate obtained from the print data 74. For example, a template shown in
Hereinafter, a procedure for density correction in the present embodiment will be described with reference to
In step S217, the white correction candidate area acquisition unit 251 obtains the white correction candidate area 81 described above. The processes of steps S218 to S220 are similar to the processes of steps S118 to S120 in the first embodiment.
In step S221, the white correction determination unit 245 determines whether it is necessary to perform white correction based on the print data 74 and the white correction candidate area 81 obtained in step S217. As a result, when it is necessary to perform white correction, the processing proceeds to step S222, and when it is not necessary to perform white correction, the processing proceeds to step S230. When an area where single-color printing is performed is included in the white correction candidate areas 81, it is determined that it is necessary to perform white correction.
In step S222, the correction target nozzle specification unit 246 specifies the correction target nozzle described above based on the print data 74 and the white correction candidate area 81 obtained in step S217.
The processes of steps S224 to S230 are similar to the processes of steps S124 to S130 in the first embodiment.
According to the present embodiment, white correction for correcting the density data such that the white ink is ejected from the white ink ejection nozzle specified based on the predetermined pattern is performed for an area where single-color printing is performed among the head connection area described above. As described above, the wet spreading range of the color ink on the base material 12 is larger when the color ink is ejected onto the white ink that has been ejected onto the base material 12 than when the color ink is directly ejected onto the base material 12. Therefore, by ejecting the ink from each ink ejection head 150 based on the density data after white correction, the color ink sufficiently spreads on the base material 12 in the area to be subjected to white correction, and the occurrence of color unevenness in the head connection area is prevented effectively. From the above, the inkjet printing apparatus capable of improving the quality of printed matter is achieved. Since the occurrence of color unevenness in the head connection area is effectively prevented, the necessity of reprinting is reduced compared to the related art, and the consumption of the base material and the ink can be reduced. In this way, it is possible to contribute to the achievement of the SDGs.
In a case where so-called solid image printing is performed using an inkjet printing apparatus, the dot size of ink ejected from a nozzle may become insufficient depending on printing conditions and base material used, and print quality satisfying a user may not be obtained. Therefore, in the present embodiment, white correction is performed to improve the print quality of the solid image.
The overall configuration of the printing system (cf.
Hereinafter, density correction in the present embodiment will be described.
The white correction determination unit 245 determines whether to perform white correction, based on the base material information 73 and the print data 74. Then, the determination result 75 is outputted from white correction determination unit 245. In this regard, in the present embodiment, similarly to the first embodiment, it is determined that white correction is not to be performed when the base material used for printing is other than a white base material, based on the base material information 73. Based on the print data 74, when there is an area where a solid image is to be formed (an area where the density of the color ink is 100%) in the print area, it is determined that white correction is to be performed. From the above, when the base material used for printing is a white base material and there is an area where a solid image is to be formed in the print area, it is determined that white correction is to be performed.
The correction target nozzle specification unit 246 specifies a correction target nozzle from among many white ink ejection nozzles included in the ink ejection head 150(W) for white ink based on the print data 74 when the determination result 75 outputted from the white correction determination unit 245 indicates that white correction is to be performed. Then, the correction target nozzle information 76 for specifying the correction target nozzle is outputted from the correction target nozzle specification unit 246. In the present embodiment, the correction target nozzle is specified based on the color for forming the solid image and the area (range) for forming the solid image. For example, it is assumed that, according to the print data 74, the shaded area denoted by reference numeral 85 in
A procedure for density correction in the present embodiment will be described with reference to the flowchart shown in
In step S121, the white correction determination unit 245 determines whether it is necessary to perform white correction, based on the print data 74. As a result, when it is necessary to perform white correction, the processing proceeds to step S122, and when it is not necessary to perform white correction, the processing proceeds to step S130. In the present embodiment, when there is an area where a solid image is to be formed in the print area, it is determined that it is necessary to perform white correction.
In step S122, the correction target nozzle specification unit 246 specifies the correction target nozzle described above based on the print data 74. At this time, the correction target nozzle is specified, based on the template for white correction, from among the plurality of white ink ejection nozzles corresponding to the area where the solid image is to be formed.
According to the present embodiment, white correction that corrects the density data such that the white ink is ejected from the white ink ejection nozzle specified based on the predetermined pattern is performed for an area where a solid image is to be formed. As described above, the wet spreading range of the color ink on the base material 12 is larger when the color ink is ejected onto the white ink that has been ejected onto the base material 12 than when the color ink is directly ejected onto the base material 12. Therefore, by ejecting the ink from each ink ejection head 150 based on the density data after white correction, the color ink sufficiently spreads on the base material 12 in the area where the solid image is printed, and the dot size of the color ink becomes larger than in the related art. This improves the print quality of the solid image. From the above, the inkjet printing apparatus 10 capable of improving the quality of printed matter is achieved.
To summarize the first to third embodiments, the processing is performed schematically by the procedure shown in
The present invention is not limited to the above embodiments (including the modification), and various modifications can be made without departing from the gist of the present invention. For example, although the inkjet printing apparatus 10 that performs printing using UV ink is exemplified in each of the above embodiments, the present invention can also be applied to a case where an inkjet printing apparatus that performs printing using ink cured by irradiation with radiation other than ultraviolet rays is adopted.
This application is an application claiming priority based on Japanese Patent Application No. 2022-150159 entitled “Printing Apparatus and Printing Method” filed on Sep. 21, 2022, and the contents of which are herein incorporated by reference.
A printing apparatus with the configuration described below is also conceivable from the above disclosure.
A printing apparatus that performs printing by ejecting ink onto a printing medium, the printing apparatus comprising:
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-150159 | Sep 2022 | JP | national |
