Patent Grant
11124005
The present disclosure relates to an image recording apparatus configured to record an image on a recording medium, an information processing method, and a storage medium.
Inkjet recording apparatuses that include a recording head with a plurality of ejection openings have been widely used. Using the inkjet recording apparatus, a desired color tone may not be appeared in an image due to a difference in ejection characteristics among recording heads of the inkjet recording apparatus. In relation to the difference in ejection characteristics among the recording heads, color shift correction processing is performed to a color difference that occurs in an image.
Meanwhile, a clear ink that contains no colorant is used to increase image quality of a recorded image and add glossiness to the recorded image. The above-described difference in ejection characteristics occurs also in the case where the clear ink is used. In other words, the difference in ejection characteristics of the clear ink also needs to be corrected as in the case of an ink that contains a colorant. In the correction process, an issue arises that the measurement accuracy of a patch pattern for acquiring an ejection characteristic of a clear ink is low.
Japanese Patent Application Laid-Open No. 2017-217891 discusses a technique in which patches that include a black ink layer formed using a black ink under a clear ink layer are recorded in calibration of a clear ink that contains no colorant. The method discussed in Japanese Patent Application Laid-Open No. 2017-217891 estimates an amount of ejection by calculating an interference color from a measurement result of the patches for calibration of the clear ink. Specifically, light-emitting diodes (LEDs) R, G, and B of light emitting portions of an optical sensor are sequentially turned on, and specular reflection light is read, and an amount of ejection of the clear ink is estimated from an intensity ratio of the three colors.
According to an aspect of the present disclosure, an image recording apparatus configured to record an image on a recording medium includes a recording unit configured to record a test pattern for a clear recording material by forming a second layer of the clear recording material containing no colorant on a first layer formed on the recording medium, the first layer being a layer of a color recording material containing a colorant, an acquisition unit configured to acquire a reflection intensity of specular reflection light of the test pattern for the clear recording material, and a generation unit configured to generate information for determining an application amount of the clear recording material in image recording, based on the reflection intensity acquired by the acquisition unit and a target value indicating the reflection intensity of the specular reflection light with respect to the application amount of the clear recording material.
Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Various exemplary embodiments of the present disclosure will be described below with reference to the drawings.
In the recording apparatus 200, a control unit 20 includes a central processing unit (CPU) 20a, such as a microprocessor, a read-only memory (ROM) 20c, and a random access memory (RAM) 20b as a memory. The ROM 20c stores a control program of the CPU 20a and various types of data such as parameters that are necessary for recording operations. The RAM 20b is used as a work area of the CPU 20a and temporarily stores various types of data, such as image data received from the host apparatus 100 and generated recording data. Further, the ROM 20c stores a lookup table (LUT) as correction information, and the RAM 20b stores patch pattern data for patch pattern recording. Alternatively, the LUT can be stored in the RAM 20b, and the patch pattern data can be stored in the ROM 20c. Further, a color shift correction LUT described below and a control program for generating the color shift correction LUT are stored in the ROM 20c.
The control unit 20 performs input-output processing to input data and parameters for use in recording, such as image data, and receive output data and parameters for use in recording to and from the host apparatus 100 via the interface 21. The control unit 20 also inputs various types of information, such as a character pitch and character type, via an operation panel 22. Further, the control unit 20 outputs ON/OFF signals for driving motors 23 to 26 via the interface 21. Further, the control unit 20 outputs an ejection signal to a driver 28 and controls driving of a recording element for ejecting an ink from a recording head.
Further, this control system includes the interface 21, the operation panel 22, a multi-purpose sensor 102, and drivers 27 and 28. The driver 27 drives the carriage driving motor 23 for driving a carriage 6, the sheet feeding roller driving motor 24 for driving a sheet feeding roller (not illustrated), the sheet conveyance roller driving motor 25 for driving a sheet conveyance roller 3, and the sheet conveyance roller driving motor 26 for driving a sheet conveyance roller 4 based on an instruction from the CPU 20a. Similarly, the driver 28 drives a recording head 5.
The recording head 5 is mounted on the carriage 6. Driving force from the carriage driving motor 2 is transmitted to the carriage 6 via a belt 7 and pulleys 8a and 8b. The driving force causes the carriage 6 to scan forward and backward along a guide shaft 9 in the direction of an arrow B (hereinafter, referred to as “scan direction”) in
The recording head 5 is moved to a home position as needed, and an ejection recovery apparatus provided at the home position performs a recovery operation to recover the recording head 5 from a state where ejection from ejection openings fails due to a clogged opening. After the recording and scanning by the recording head 5, the sheet conveyance rollers 3 and 4 are driven, and the recording medium 1 is conveyed in the sheet conveyance direction by a predetermined amount. The recording and scanning by the recording head 5 and the operation of conveying the recording medium 1 are alternately repeated to record an image on the recording medium 1.
In the present exemplary embodiment, inks are used as recording materials, color inks are used as color recording materials containing a colorant, and a clear ink is used as a clear recording material containing no colorant. The recording head 5 according to the present exemplary embodiment ejects four color inks that are a cyan ink (C) containing a cyan colorant, a magenta ink (M) containing a magenta colorant, a yellow ink (Y) containing a yellow colorant, and a black ink (K) containing a black colorant. The recording head 5 further ejects a clear ink (S) containing no colorant. The inks are supplied from ink cartridges (not illustrated) and ejected from ejection opening rows 5a to 5e. In
<Ink Formulation>
Ink formulation will be described in detail below. Unless otherwise specified, the terms “parts” and “%” refer to “parts by mass” and “% by mass”.
<Preparation of Pigment Dispersion Liquid>
(Preparation of Black Pigment Dispersion Liquid)
First, 20.0 parts of a pigment, 60.0 parts of an aqueous resin solution, and 20.0 parts of water were put into a bead mill (LMZ2; manufactured by Ashizawa Finetech) with a fill rate of 80% of zirconia beads in 0.3 mm diameter and dispersed at 1,800 revolutions per minute (rpm) for five hours. A carbon black (product name: Printex® 90; manufactured by Degussa) was used as the pigment. An aqueous solution of 20.0% resin content (solid content) containing Joncryl® 678 (manufactured by Johnson Polymer), which is a styrene-acrylic acid copolymer, neutralized with potassium hydroxide of an equivalent weight to an acid value was used as the aqueous resin solution. Thereafter, the mixture was centrifuged at 5,000 rpm for 30 minutes to remove aggregated components, and the resulting mixture was diluted with an ion-exchange water to obtain a black pigment dispersion liquid with 15.0% pigment content and 9.0% water-soluble resin (dispersion agent) content.
(Preparation of Magenta Pigment Dispersion Liquid)
The pigment was changed to a C. I. pigment red 122 (product name: toner magenta E02; manufactured by Clariant). A similar procedure to the above-described procedure of preparing the black pigment dispersion liquid, except for the pigment, was conducted to obtain a magenta pigment dispersion liquid with 15.0% pigment content and 9.0% water-soluble resin (dispersion agent) content.
(Preparation of Cyan Pigment Dispersion Liquid)
The pigment was changed to a C. I. pigment blue 15:3 (product name: toner cyan BG; manufactured by Clariant). A similar procedure to the above-described procedure of preparing the black pigment dispersion liquid, except for the pigment, was conducted to obtain a cyan pigment dispersion liquid with 15.0% pigment content and 9.0% water-soluble resin (dispersion agent) content.
(Preparation of Yellow Pigment Dispersion Liquid)
The pigment was changed to a C. I. pigment yellow 74 (product name: Hansa Brilliant Yellow 5GX; manufactured by Clariant). A similar procedure to the above-described procedure of preparing the black pigment dispersion liquid, except for the pigment, was conducted to obtain a yellow pigment dispersion liquid with 15.0% pigment content and 9.0% water-soluble resin (dispersion agent) content.
<Ink Preparation>
After the components (unit: %) specified in an upper section of Table 1 were mixed together, the mixture was filtered under pressure with a membrane filter (HDC® II filter; manufactured by Pall) having a pore size of 1.2 μm to prepare pigment inks 1 to 6. The ion-exchange water was used in an amount that was determined so that the total content of the components was 100.0%. Acetylenol® E100 is a surfactant manufactured by Kawaken Fine Chemicals. In a lower section of Table 1, the pigment contents (unit: %) in the pigment inks are specified. The obtained inks were put into respective cartridges.
<Preparation of Clear Ink S>
Preparation of Aqueous Resin Solution
An aqueous solution of 20.0% resin content (solid content) containing Joncryl® 678 (manufactured by Johnson Polymer), which is a styrene-acrylic acid copolymer, neutralized with potassium hydroxide of an equivalent weight to an acid value was used as the aqueous resin solution.
Ink Preparation
After the components (unit: %) specified in Table 2 were mixed together, the mixture was filtered under pressure with a membrane filter (HDC® II filter; manufactured by Pall) having a pore size of 1.2 μm to prepare a resin-containing clear ink S. The ion-exchange water was used in an amount that was determined so that the total content of the components was 100.0%. Acetylenol® E100 is a surfactant manufactured by Kawaken Fine Chemicals. The obtained clear ink S was put into a cartridge.
The clear ink (S) according to the present exemplary embodiment is an ink that is to be applied onto a color ink layer formed by a color ink. The clear ink is applied onto the color ink so that the gloss value of the surface of the recorded image is increased, compared to a case where there is only a color ink layer.
(Multi-Purpose Sensor)
The multi-purpose sensor 102 includes two light emitting portions 302 and 304 and a light receiving portion 303. The light emitting portions 302 and 304 are configured with three visible light-emitting diodes (LEDs) R, G, and B, and the light receiving portion 303 is configured with a photo diode. Illumination light from the light emitting portion 302 enters the recording medium 1 at an angle of 45 degrees, and the light that is reflected at the same angle, i.e., specular reflection light, is received by the light receiving portion 303. The light emitting portion 302 and the light receiving portion 303 in combination function as a specular reflection sensor, which will be referred to as a specular reflection sensor 310. As described below, the specular reflection light varies in the amount of reflection light due to an effect of an uneven surface of the recording medium 1 and an index of refraction. Thus, the specular reflection sensor 310 is used to detect the gloss value of the recording medium 1. Further, illumination light from the light emitting portion 304 enters the recording medium 1 at an angle of zero degrees, and the light that is reflected is received by the light receiving portion 303. Specifically, the light emitting portion 304 and the light receiving portion 303 in combination function as a diffuse reflection sensor, which will be referred to as a diffuse reflection sensor 311. The diffuse reflection sensor 311 detects diffuse reflection light that does not contain specular reflection light. Thus, the diffuse reflection sensor 311 is used as a density sensor that detects the color density of a surface of the recording medium 1.
In a calibration process described below, the conveyance of the recording medium 1 in the sheet conveyance direction and the scan of the carriage 6 with the multi-purpose sensor 102 in the scan direction are alternately performed. The diffuse reflection sensor 311 of the multi-purpose sensor 102 detects a density of each patch recorded on the recording medium 1 as an optical reflection rate and measures a patch pattern recording density. A patch formed on the recording medium 1 is illuminated with light, and a reflection intensity level that reflects the density of the patch is detected. In a case where the color of the surface of the recording medium 1 is white, the reflection intensity is high, and the higher the density of the patch is, the lower the reflection intensity becomes. On the other hand, the specular reflection sensor 310 of the multi-purpose sensor 102 detects the gloss value of each patch recorded on the recording medium 1 as an optical reflection rate and measures the gloss value. In the present exemplary embodiment, a straight line that connects a central point of an illumination range of illumination light emitted from the light emitting portion 304 to a measurement surface and a center of the light emitting portion 304 will be referred to as an optical axis of a light emitting element. The optical axis of the light emitting element is also a center of a light flux of the illumination light. A line that connects a central point of a region (range) of the measurement target surface where the light receiving portion 303 can receive light and a center of the light receiving portion 303 will be referred to as an optical axis of a light reception element (light reception axis). The light reception axis is also a center of a light flux of reflection light that is reflected at the measurement surface and received by the light receiving portion 303. Alternatively, instead of sharing the light receiving portion 303 as the light receiving portion of the specular reflection sensor 310 and the light receiving portion of the diffuse reflection sensor 311, a light receiving portion can be provided to each sensor. Further, the number of colors of the LEDs of the light emitting portions 302 and 304 are not limited to that described above.
(Image Processing Method)
Next, an image processing method for generating recording data for recording an image in the recording apparatus 200 will be described below.
First, image data represented by 8-bit luminance signals R, G, B is transmitted from the host apparatus 100 to the recording apparatus 200. In this process, the image data is multi-valued data with 256 gradations for each color. Then, in step S401, color space conversion preprocessing (hereinafter, also referred to as “color preprocessing”) is performed. The image data represented by the multi-valued luminance signals R, G, B is converted into R′, G′, B′ multi-valued data using a multi-dimensional LUT 401. The color preprocessing is performed to correct the difference between a color space of an input image represented by the R, G, B image data in the recording target and a color space that is reproducible by the recording apparatus 200.
Next, in step S402, color conversion processing (hereinafter, also referred to as “color postprocessing”) is performed. The recording apparatus 200 receives the R′, G′, B′ data that has undergone the color preprocessing from the host apparatus 100. The received R′, G′, B′ data is converted into C, M, Y, K, S multi-valued data, which are ink colors, using a multi-dimensional LUT 402. The color postprocessing is the processing of converting RGB value image data at input end that is represented by luminance signals into CMYKS value image data at output end that is represented by density signals.
In step S403, output gamma correction processing is performed for each color on the C, M, Y, K, S multi-valued data having undergone the color postprocessing using a one-dimensional LUT. In general, the relationship between the number of ink droplets (dots) applied per unit area of the recording medium 1 and a recording characteristic obtained by measuring a recorded image, such as reflection density, is not linear. Thus, the processing of correcting C, M, Y, K, S multi-valued input gradation levels so that the relationship between C, M, Y, K, S 10-bit input gradation levels and a density level of an image recorded based on the C, M, Y, K, S 10-bit input gradation levels becomes linear is needed. This processing is the output gamma correction processing. The one-dimensional LUT that is used in step S403 will be referred to as an output gamma correction table 403.
In step S404, color shift correction processing is performed. An output gamma correction table that is generated for a recording head having a normal recording characteristic is often used as the output gamma correction table 403 in step S403. However, as described above, each recording head or ejection opening has individual variability in ejection characteristics. Thus, with an output gamma correction table for correcting a recording characteristic of a recording head or ejection opening having a normal ejection characteristic alone, it is not possible to perform density correction as appropriate with respect to every recording head or ejection opening. Thus, in the present exemplary embodiment, color shift correction processing is performed on the C, M, Y, K, S multi-valued data having undergone the output gamma correction so that the amount of each ink to be applied in image recording is determined.
A one-dimensional LUT for color shift correction for use in color shift correction processing is set based on information that is acquired in the calibration process and specifies an ejection characteristic of each ejection opening row. The information that specifies the ejection characteristics is density value information for the color inks (C, M, Y, K) containing a colorant and gloss value information for the clear ink (S) containing no colorant. While the processing of correcting data that specifies an amount of ink as a recording material to be applied is referred to as “color shift correction” in the present specification, the color shift correction is not limited to the cases where predefined data is corrected, and the processing in a case where new determination is performed is also referred to as “color shift correction”. Further, the processing of determining an application amount of the clear ink containing no colorant with respect to the ejection characteristic is also referred to as “color shift correction processing” as in the cases of the color inks.
After the color shift correction processing is performed, in step S405, quantization processing is performed, such as halftone processing using error diffusion or dither pattern and index expansion. As a result of the processing, C, M, Y, K, S binary recording data that specifies whether an ink droplet is to be ejected or not ejected from the recording head 5 is generated, and the generated data is output.
(Calibration Process)
Next, the calibration process that is a feature of the present exemplary embodiment will be described below. The calibration process is a process of generating the color shift correction LUT described above and is executed by a user instruction while no image recording is performed. Alternatively, the calibration process can be executed automatically when a predetermined condition is satisfied.
The calibration according to the present exemplary embodiment includes two processes, a process of acquiring density characteristics with respect to the color inks C, M, Y, and K and generating one-dimensional correction LUTs for the color inks and a process of acquiring a gloss value characteristic with respect to the clear ink (S) containing no colorant and generating a one-dimensional correction LUT for the clear ink. A reason therefor will be described below.
First, Japanese Patent Application Laid-Open No. 2017-217891 described above discusses a clear ink calibration method, but the balance of the intensity ratio among three colors that are read changes significantly due to a factor such as a minor error in measurement, so that it is difficult to estimate an amount of ejection of the clear ink with great accuracy. In contrast, according to the present exemplary embodiment, the amount of ejection is estimated from the reflection intensity of specular reflection light of a test pattern for the clear ink.
In the acquisition of the gloss value characteristic of the clear ink, the color inks containing a colorant are applied as a background to each patch of the patch pattern for the clear ink (for the clear recording material).
In the case of using the color inks as a background, it is desirable that the densities of the color inks should be adequate values and that the density characteristics of the color inks should be corrected as appropriate, because if the densities of the color inks used in the undercoat layer vary, even if the same amount of the clear ink is applied onto the color inks, the detected gloss value varies. Thus, in the present exemplary embodiment, before the patch pattern for the clear ink is recorded, the patch patterns for the color inks (for the color recording material) are recorded and the recorded patch patterns are measured, followed by calibration of the color inks. Then, in the calibration of the color inks, the one-dimensional correction LUTs that are generated as information about the application amounts of the color inks are applied to image data (patch data) for recording the patch pattern for the clear ink, and then the patch pattern for the clear ink is recorded. With the above-described configuration, a decrease in calibration accuracy that originates from the ejection characteristics of the color inks applied as a background is reduced in acquisition of the gloss value characteristic of the clear ink.
In step S804, a timer counter is started to wait for a predetermined period of time so that the recorded patch pattern is dried. In step S805, in a case where the timer counter indicates that the predetermined period of time passes (YES in step S805), then in step S806, the measurement of the reflection intensity of the patch pattern is started using the diffuse reflection sensor 311 of the multi-purpose sensor 102. The reflection intensity is measured by sequentially turning on the LEDs of the light emitting portion 304 of the multi-purpose sensor 102 that correspond to the density measurement target ink colors and then reading reflection light (diffusion light) using the light receiving portion 303. For example, the green (G) LED is turned on in measuring the patch pattern recorded using the magenta (M) ink and a white portion (white) of the sheet where no patch pattern is recorded. The blue (B) LED is turned on in measuring the patch pattern recorded using the yellow (Y) ink and the black (K) ink and the white portion (white) of the sheet where no patch pattern is recorded. The red (R) LED is turned on in measuring the patch pattern recorded using the cyan (C) ink and the white portion (white) of the sheet where no patch pattern is recorded. The measurement results of the white portion (white) of the sheet are used as a reference value in calculating the density values of the patch patterns recorded using the color inks.
If the reading of the patch patterns is finished, then in step S807, the density value of the patch pattern for each corresponding ejection opening row is calculated based on the measurement values of the respective patches and the measurement values of the white portion of the sheet. The calculated density values are stored in the RAM 20b in a main body of the recording apparatus 200. In step S808, the recording medium 1 is discharged, and the process is ended.
Next, the one-dimensional correction LUTs for color shift correction of the color inks are generated based on the density characteristics of the color inks that are acquired through the process illustrated in
Next, a process of acquiring the gloss value characteristic of the recording apparatus 200 with respect to the clear ink S will be described below with reference to
In step S904, the timer counter is started to wait for a predetermined period of time so that the recorded patch pattern is dried. In step S905, in a case where the timer counter indicates that the predetermined period of time passes (YES in step S905), then in step S906, the measurement of the reflection intensity of the patch pattern is started using the specular reflection sensor 310 of the multi-purpose sensor 102. The reflection intensity is measured by turning on the LED of the light emitting portion 302 of the multi-purpose sensor 102 and then reading reflection light (specular reflection light) using the light receiving portion 303. In the present exemplary embodiment, one of the LEDs R, G, and B is used.
If the reading of the patch patterns is finished, then in step S907, the gloss value of the patch pattern for each corresponding ejection opening row is calculated based on the measurement values of the respective patches. The calculated gloss values are stored in the RAM 20b in the main body of the recording apparatus 200. Thereafter, in step S908, the recording medium 1 is discharged, and the process is ended.
Next, the one-dimensional correction LUT for color shift correction of the clear ink is generated based on the gloss value characteristic of the clear ink that is acquired through the process illustrated in
In the present exemplary embodiment, one of the LEDs R, G, and B of the light emitting portion 302 of the multi-purpose sensor 102 is turned on to emit light and the reflection intensity of the specular reflection light is read in the acquisition of the gloss value characteristic from the patch pattern for the clear ink. This is based on the finding of the studies by the present inventors that the difference in the application amount of the clear ink can be acquired with great accuracy from the reflection intensity of the specular reflection light. In conventionally-known methods, an amount of ejection is estimated based on a balance of an intensity ratio of specular reflection light as discussed in Japanese Patent Application Laid-Open No. 2017-217891, or an amount of ejection is estimated from a spectral reflectance by acquiring a measurement target color from a result of measuring specular reflection light and estimating an ejection characteristic of a clear ink from the acquired color. In the method of estimating an ejection characteristic from a color of reflection light, however, it is difficult to realize high measurement accuracy, because the reflection light sometimes exhibits similar colors even if there is a significant difference in the application amount of the clear ink. Furthermore, it is also difficult to realize reproducibility in measurement. On the contrary, in the case where the application amount of the clear ink is acquired from the reflection intensity of the specular reflection light according to the present exemplary embodiment, the relationship between the application amount of the clear ink and the reflection intensity is a one-dimensional proportional relationship as illustrated in
As described above, in the present exemplary embodiment, the patch pattern with the color inks applied as an undercoat layer under the clear ink layer is recorded in the calibration for correcting the gloss value characteristic of the clear ink. Then, the reflection intensity of the specular reflection light of the patch pattern for the clear ink is acquired using the specular reflection sensor 310, and the LUT for color shift correction of the clear ink is generated from the reflection intensity. With this configuration, the application amount of the clear ink can be corrected with greater accuracy than that in the method of estimating the application amount of the clear ink from the color of a patch.
Furthermore, before the patch pattern for the clear ink is recorded, the color inks to be applied as an undercoat layer are calibrated, and correction LUTs for the color ink are generated. Then, the generated correction LUTs for the color inks are applied to data for recording a color ink layer for use as a background of the patch pattern for the clear ink. In this way, the effect of the ejection characteristics of the color inks is reduced in the calibration of the clear ink.
It is desirable to record the patch patterns for the color inks to be used as a background and generate the one-dimensional correction LUTs using measurement values of the patch patterns immediately before the patches for the clear ink are recorded. It is also desirable not to record an image based on other image data between the recording of the patch patterns for the color inks and the recording of the patch pattern for the clear ink. As long as the patch pattern for the clear ink is to be recorded after the patch patterns for the color inks are measured, the patch patterns for the color inks and the patch pattern for the clear ink can be recorded on the same recording medium.
Further, it is more desirable to generate the one-dimensional LUTs for color shift correction for each condition such as a recording medium, resolution, and use environment. Further, the above-described calibration processing can be executed each time an image recording instruction job is received, or the one-dimensional correction LUTs that are generated in previous execution can be stored in a memory and the stored LUTs can be used. Further, the one-dimensional LUTs for color shift correction can be selected from a plurality of stored tables and the selected LUTs can be set.
While the black ink, which is an achromatic color, is used as a background of the patch pattern for the clear ink in the present exemplary embodiment, the background is not limited to the black ink and any color ink can be used. In order to calibrate the clear ink with great accuracy, the density of the image of the color ink layer recorded as an undercoat layer is desirably high. An optical density (OD) value that is an optical density in measuring the undercoat layer is desirably 0.5 or greater, more desirably 1.0 or greater. In the case where the black ink, which is an ink of an achromatic colorant, is used as an undercoat layer, the LED to be used in measuring the patch pattern for the clear ink can be an LED of any color. Meanwhile, in a case where a color ink such as the color ink C, M, or Y is used as an undercoat layer, it is desirable to measure using a color LED having a color that is at least 90 degrees apart from the color of the color ink in a hue circle.
In the first exemplary embodiment described above, the example in which the one-dimensional LUTs for color shift correction of the color inks are generated from the density values read from the patch patterns formed using the color inks using the diffuse reflection sensor 311 is described. In a second exemplary embodiment, an example in which one-dimensional LUTs for color shift correction of the color inks are generated from density values read from patch patterns formed by applying the color inks and the clear ink will be described below.
In the present exemplary embodiment, the patches recorded using both the clear ink (S) and the color ink (one of the colors C, M, Y, and K) are formed also by applying the clear ink onto the color ink.
In the present exemplary embodiment, first, a patch pattern is recorded using one color (black ink in the present exemplary embodiment) among the color inks, and calibration is performed, and a correction LUT with respect to the ejection characteristic of the black ink is generated (
As described above, in the present exemplary embodiment, the clear ink is calibrated after the color ink that is to be used as an undercoat layer is calibrated as in the first exemplary embodiment. The difference from the first exemplary embodiment is that after the clear ink is calibrated, the color inks are calibrated. The patches having the clear ink layer formed on the color ink layer is used in the calibration of the color inks. In this way, the color inks are calibrated in a state that is similar to real recording in which the clear ink is applied onto the color inks.
In the present exemplary embodiment, since the black ink is used as an undercoat layer, the black ink is calibrated before the clear ink is calibrated. Then, after the clear ink is calibrated, the color inks of all the colors are calibrated using the patches to which the clear ink is applied. In a case where a color other than the black ink is used as an undercoat layer, it is desirable to calibrate the ink of the color before the clear ink is calibrated. Although it is desirable to calibrate the color inks of all the colors using the patches to which the clear ink is applied after the clear ink is calibrated, the ink that is used as a background of the clear ink does not have to be thusly calibrated, because the ink is already calibrated.
In the first and second exemplary embodiments described above, the examples in which the one-dimensional LUTs for color shift correction of the color inks are generated from the density values of the patch patterns using the diffuse reflection sensor 311 are described. In a third exemplary embodiment, an example in which one-dimensional LUTs for color shift correction of the color inks are generated from gloss values acquired by measuring patch patterns using the specular reflection sensor 310 will be described below.
In the present exemplary embodiment, the patches recorded using both the clear ink (S) and the color ink (one of the colors C, M, Y, and K) are formed also by applying the clear ink onto the color ink.
In the present exemplary embodiment, first, patch patterns are recorded using the color inks of all the colors (four colors C, M, Y, and K), and calibration is performed, and correction LUTs with respect to the ejection characteristics of the color inks of the respective colors are generated (
As described above, in the present exemplary embodiment, when the color inks are calibrated, the patches with the clear ink layer formed by applying the clear ink on the color ink layer are recorded, and the gloss values of the recorded patches are measured. Then, the one-dimensional LUTs for color shift correction are generated based on the measured gloss values. With this configuration, the correction LUTs can be generated from the gloss values based on the measurement results of the specular reflection light.
In the first to third exemplary embodiments described above, the examples in which the color shift correction processing is executed on the clear ink using the one-dimensional LUTs for color shift correction are described. In a fourth exemplary embodiment, a method of generating data for applying the clear ink using a thinning mask based on quantized color ink data will be described below.
While the one-dimensional correction LUTs are generated as correction information for correcting the application amount in the above-described exemplary embodiments, the present disclosure is not limited to the form of a lookup table. Alternatively, the correction information can be held in the form of a mathematical function. While the inks are used as recording materials that are applied to recording mediums in the above-described exemplary embodiments, the recording materials are not limited to those described above. A color toner can be used as a color recording material besides the color inks, and a clear toner can be used as a clear recording material besides the clear ink.
As an alternative to a clear recording material, a reaction solution which reacts with a colorant contained in a color ink can be used. The reaction solution reacts with a colorant and the colorant flocculates. In a case of applying the reaction solution, it is desirable that the reaction solution is applied before application of a color ink or is applied together with a color ink. More specifically, for example, a color ink layer is formed by applying a color ink to form a patch on a reaction solution layer formed using the reaction solution, or the reaction solution and a color ink are applied together in a scan to form a layer in which the reaction solution and the color ink is mixed. Similar to the case using a clear ink, a plurality of patches each having a different application amount of the reaction solution is formed and gloss values of the patches are measured. With this configuration, an amount of ejection of the reaction solution is estimated so that a correction table can be generated, as in the case using a clear ink.
While the patch patterns including the plurality of patches are recorded in the above-described exemplary embodiments, the recording is not limited to that described above, and any configuration by which one or more patches are recorded can be employed. The correction value determination is not limited to the configuration by which correction values are determined using the target values, and a configuration can be employed by which an amount of ejection is estimated based on measurement results of a plurality of patches of different application amounts of the clear ink and correction values are determined. Depending on a material contained in the clear ink, a gloss value of a recorded image is not always increased by an increase in the application amount, and when the clear ink covers a recording medium to some extent, further application of the clear ink does not always increase the gloss value. This characteristic can be used to estimate an amount of ejection based on measurement results of gloss values of a plurality of patches of different application amounts.
Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-019200, filed Feb. 5, 2019, which is hereby incorporated by reference herein in its entirety.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2019-019200 | Feb 2019 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 20130100191 | Miyamoto | Apr 2013 | A1 |
| 20160347081 | Fukasawa | Dec 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 2017-217891 | Dec 2017 | JP |
| Number | Date | Country | |
|---|---|---|---|
| 20200247163 A1 | Aug 2020 | US |
