JP6598711B2 - Inkjet recording apparatus and pattern recording method for correcting applied amount - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and a pattern recording method for correcting an applied amount, and more particularly to a technique for correcting the applied amount of clear ink that is applied to a recording medium together with color material ink during recording.

  By using an appropriate amount of clear ink together with the color material ink, it is possible to improve the fastness of the recorded matter or increase the recording density (OD). In a recording head that discharges such clear ink, as in the case of color material ink, the discharge amount may vary among nozzles due to manufacturing variations and aging of the recording head. On the other hand, as is well known for color inks, so-called head shading (HS) correction can be performed to adjust the amount of clear ink applied.

  When this HS correction is performed, clear ink is ejected and a pattern for HS is recorded. This pattern can detect a difference in density according to the amount of clear ink not including a color material. desirable. Patent Document 1 discloses a technique for detecting density changes due to ink bleeding with respect to clear ink in the overlapped area, as a technique for detecting density changes due to application of clear ink. Is disclosed.

JP 2005-22216 A

  However, even if the technique described in Patent Document 1 is used for recording a pattern for HS (applied amount correction), depending on the combination of the type of recording medium on which the pattern is recorded and the ink, the difference in the applied amount of clear ink may be different. In some cases, the concentration change sufficient for detection cannot be obtained. As a result, it may not be possible to perform highly accurate application amount correction.

  The present invention provides an ink jet recording capable of increasing a difference in density according to a difference in the amount of clear ink applied in an area where the color material ink and the clear ink overlap in the recording of the clear ink application amount correction pattern. An object of the present invention is to provide an apparatus and a pattern recording method for correcting the applied amount.

  In order to solve the above-described problems, the present invention provides a color material ink recording head for ejecting a plurality of color material inks having different color material types, and a plurality of a plurality of color inks for ejecting clear ink that does not include a color material. Inkjet recording capable of recording a correction pattern for correcting the application amount of the clear ink when recording on a recording medium using a clear ink recording head having a nozzle row in which nozzles are arranged An apparatus, wherein a plurality of recordings recorded by the first color material ink and the second color material ink, and a plurality of recordings recorded by the clear ink are different from each other in the plurality of color material inks. A recording means for recording the correction pattern on a recording medium, each of which has an overlapping portion; and when the correction pattern is recorded, the clear ink, A recording head for the color material ink, a recording head for the clear ink, and a control means for controlling movement of the recording medium so that recording is performed in the order of one color material ink and the second color material ink. It is characterized by that.

  According to the above configuration, in recording the clear ink application amount correction pattern, it is possible to increase the density difference according to the difference in the clear ink application amount in the area where the color material ink and the clear ink overlap. It becomes.

1 is a schematic diagram illustrating a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a configuration of a recording chip provided with nozzles of the recording head illustrated in FIG. 1. It is a figure explaining especially nozzle arrangement | positioning of each recording chip shown in FIG. It is a schematic diagram for demonstrating the detail of the reflection type optical sensor shown in FIG. It is a block diagram which shows the control structure of the inkjet recording device which concerns on one Embodiment of this invention. FIG. 5 is a diagram illustrating an example of density unevenness caused by a difference in ejection characteristics between nozzles in a recording head according to an embodiment of the present invention. It is a figure which shows the color wavelength characteristic of the light emitting diode of R, G, and B color used in the light emission part which concerns on one Embodiment of this invention. (A)-(d) is a figure for demonstrating the measurement principle using the optical characteristic of the irradiation light from the said light emission part. It is a figure for demonstrating the optical characteristic of the dot of the black (K) coloring material ink recorded on the recording medium, and the measurement result using an optical sensor. Similarly, it is a figure for demonstrating the measurement result using the optical characteristic of the dot of the cyan (C) coloring material ink recorded on the recording medium, and an optical sensor. Similarly, it is a figure for demonstrating the optical characteristic of the dot of the magenta (M) color material ink recorded on the recording medium, and the measurement result using the optical sensor. Similarly, it is a figure for demonstrating the optical characteristic of the dot of the yellow (Y) color material ink recorded on the recording medium, and the measurement result using an optical sensor. (A)-(e) is a figure explaining the optical characteristic at the time of recording when not overlapping and recording when a clear ink and a color material ink single color are superimposed. (A)-(d) is sectional drawing of a recording medium for demonstrating the mode of penetration | invasion, etc. when the color material ink of the color 1 and the color 2 lands on a recording medium in order. (A)-(f) is sectional drawing of a recording medium for demonstrating the penetration | invasion mode, etc. when clear ink, color 1 ink, and color 2 ink land on a recording medium in order. (A)-(k) is a figure explaining the difference in the optical characteristic when not using with the case where clear ink is used. 6 is a flowchart showing processing for creating a clear ink application amount correction (HS) table according to the first embodiment of the present invention; It is a figure explaining the example of HS pattern for clear ink which concerns on 1st Embodiment of this invention. It is a flowchart which shows the process which records the HS pattern shown in FIG. It is a figure which shows HS pattern for clear ink which concerns on 1st Embodiment of this invention, and its recording order. It is a figure which shows an example of the measurement result of the test | inspection patch recorded with a certain chip | tip based on 1st Embodiment of this invention. It is a figure which shows the density | concentration and density variation which are measured in the chip | tip of the measurement result shown in FIG. It is a figure which shows the measurement result of the test | inspection patch recorded by the chip | tip different from the chip | tip of the measurement result shown in FIG. It is a figure which shows the density | concentration and density variation which are measured in the chip | tip of the measurement result shown in FIG. It is a flowchart which shows the process which records HS pattern for clear ink which concerns on a comparative example. FIG. 23 is a diagram showing the measurement result of the inspection patch recorded by the clear ink chip from which the measurement result shown in FIGS. 21 and 22 is obtained in accordance with the processing described above in FIG. It is a figure which shows the density | concentration and density variation which are measured in the chip | tip of the measurement result shown in FIG. FIG. 26 is a diagram showing the measurement result of the inspection patch recorded by the clear ink chip from which the measurement result shown in FIGS. 23 and 24 is obtained in accordance with the processing described above in FIG. It is a figure which shows the density | concentration and density variation which are measured in the chip | tip of the measurement result shown in FIG. It is sectional drawing which shows the line scanner used in 2nd Embodiment of this invention. It is a figure which shows HS pattern for clear ink which concerns on 2nd Embodiment of this invention. It is a flowchart which shows the process for recording HS pattern for clear ink which concerns on 2nd Embodiment of this invention. It is a figure which shows the measurement result of the reflection density of three test | inspection patches which concern on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic diagram showing a schematic configuration of an ink jet recording apparatus according to an embodiment of the present invention. The recording apparatus 1 is provided with a so-called full line type recording head 2 in which nozzles are arranged in a range corresponding to the width of the recording medium. As the recording head 2, two recording heads 21 for ejecting clear ink and a head 22 for ejecting color material ink (C, M, Y, and K ink heads are integrated) are provided. Each of these recording heads is arranged to extend in a direction (nozzle arrangement direction: Y direction) orthogonal to the conveyance direction (sub-scanning direction: X direction) of the recording medium P. Further, the clear ink recording head 21 is disposed upstream of the color material ink recording head 22 in the transport direction, whereby the clear ink is ejected and applied to the recording medium prior to the color material ink. It will be. The recording head 2 is provided at a position facing the platen 6 with the conveying belt 5 interposed therebetween. The recording head 2 is moved up and down in the direction facing the platen 6 by the head moving unit 10. The operation of the head moving unit 10 is controlled by the control unit 9. Further, the recording head 2 is provided with a nozzle for ejecting ink, a common liquid chamber to which ink in the ink tank 3 is supplied, and an ink flow path for guiding ink from the common liquid chamber to each nozzle. For example, each nozzle is provided with a heating resistance element (heater) for generating bubbles in the ink, and the ink is ejected from each nozzle by driving the heater with a head driver. The heater of each nozzle is electrically connected to the control unit 9 via the head driver 2a, and the driving of the heater is controlled in accordance with an on / off signal (ejection / non-ejection signal) from the control unit 9. The

  The recording head 2 for each ink has five ink tanks 3R, 3C, 3M for storing clear ink, cyan (C) ink, magenta (M) ink, yellow (Y) ink, and black (K) ink, respectively. 3Y and 3K (hereinafter collectively referred to as the ink tank 3) and the connection pipe 4 are connected. Each ink tank 3 can be individually attached and detached.

  The control unit 9 performs overall control of various processes in the recording apparatus 1. The control unit 9 includes, for example, a CPU 33, a memory such as a ROM 34 and a RAM 35, an ASIC, and the like. The recording apparatus 1 is an apparatus capable of recording an HS pattern for clear ink, which will be described later, under the control of the control unit 9.

  A cap 7 is disposed on the side of the recording head 2 in a state of being shifted by a half pitch with respect to the arrangement interval of the recording heads 2. The cap moving unit 8, whose operation is controlled by the control unit 9, can move the cap 7 between the side position of the recording head 2 and the position immediately below the recording head 2. Recovery processing such as capping and preliminary discharge can be performed. A reflective optical sensor 30 described later with reference to FIG. 4 is provided on the downstream side of the recording head 2 in the conveyance direction of the recording medium. The reflective optical sensor 30 can be operated in the Y direction by its carriage, and its operation is controlled via the motor driver 17.

  The conveying belt 5 is stretched over a driving roller connected to a belt driving motor 11 and conveys the recording medium P by the driving roller being driven to rotate. The operation of the conveying belt 5 through the motor driver 12 is controlled. A charger 13 is provided on the upstream side of the conveying belt 5. The charger 13 charges the conveyance belt 5 to bring the recording medium P into close contact with the conveyance belt 5. The electrification of the charger 13 is switched on / off via the charger driver 13a. The pair of feeding rollers 14 supplies the recording medium P onto the conveying belt 5. The feeding motor 15 drives and rotates the pair of feeding rollers 14. The operation of the feeding motor 15 is controlled via a motor driver 16.

  In implementing the present invention, the configuration of the recording apparatus shown in FIG. 1 is an example, and is not necessarily limited to such a configuration. For example, the configuration is not particularly limited as long as the recording head and the recording medium move relative to each other. For example, the recording head may be configured to move with respect to the recording medium.

  FIG. 2 is a diagram illustrating the configuration of a recording chip in which the nozzles of the recording head 2 shown in FIG. 1 are arranged. Since the recording head 21 for clear ink and the recording head 22 for color material ink have the same configuration, the recording head 22 for color material ink will be described as an example. For example, ten recording chips H200 (H200a to H200j) having an effective discharge width of about 1 inch and made of silicon are arranged in a staggered manner on the base substrate (support member). ing. The recording chips H200 adjacent in the Y direction are arranged with a predetermined overlap width in the nozzle array direction (Y direction), thereby enabling recording without a gap even at the joint of the recording chips. .

  FIG. 3 is a diagram for explaining the nozzle arrangement of each recording chip H200 shown in FIG. The recording chip H200 is provided with eight nozzle rows H201 to H208. The nozzle arrays H201 and H202 correspond to cyan ink, the nozzle arrays H203 and H204 correspond to magenta ink, the nozzle arrays H205 and H206 correspond to yellow ink, and the nozzle arrays H207 and H208 correspond to black ink, respectively. The nozzle arrangement pitch of each nozzle row is 600 dpi, and the two nozzle rows of each color are arranged so as to be shifted from each other by a half pitch. As a result, for each color ink, it is possible to record with a Y-direction resolution of 1200 dpi. Further, each nozzle row is formed of 600 nozzles, and accordingly, 1200 nozzles are provided for each color ink.

  On the other hand, the recording chip of the clear ink recording head 21 of the present embodiment is provided with two nozzle rows (H207, H208), and these two nozzle rows are also arranged with a half-pitch offset from each other. Recording with a resolution of 1200 in the direction is possible. Similarly, the number of nozzles is 1200. Note that the clear ink recording chip has a configuration similar to the recording head 22 for color material ink shown in FIG. 3, and eight nozzle rows are provided, of which only two nozzle rows H207 and H208 are used, and the nozzle row H201. The form which does not use -H206 may be sufficient. In this case, it is not limited that printing is performed with all nozzle rows in order to improve robustness, and that other nozzle rows are used as auxiliary nozzles for non-discharge complementation.

  FIG. 4 is a schematic diagram for explaining the details of the reflective optical sensor 30 shown in FIG. The reflective optical sensor 30 is attached to a carriage (not shown) operable in the Y direction, and includes a light emitting unit 31 and a light receiving unit 32. Light (incident light) 35 emitted from the light emitting unit 31 is reflected by the recording medium P, and the reflected light 37 is detected by the light receiving unit 32. The detection signal (analog signal) of the reflected light 37 is transmitted to the control unit 9 (FIG. 1) via a flexible cable (not shown), and is converted into a digital signal by the A / D converter in the control unit. As this optical sensor 30, a sensor having a relatively low resolution can be used, thereby reducing the cost.

  FIG. 5 is a block diagram showing a control configuration of the ink jet recording apparatus according to the embodiment of the present invention, and mainly shows a detailed configuration of the control unit 9 shown in FIG.

  The controller (control unit) 9 includes a CPU 33, a ROM 34, a RAM 35, an image processing unit 36, and a given amount correction (HS) processing unit 37 as functional configurations. The CPU 33 controls the overall operation of the recording apparatus according to the present embodiment. For example, the CPU 33 controls the operation of each unit according to a program stored in the ROM 34. The ROM 34 stores various data. The ROM 34 stores, for example, information on the type of recording medium, information on ink, information on the environment such as temperature and humidity, various control programs, and the like. The image processing unit 36 performs image processing on image data input from the host device 100 via the interface 100a. For example, multi-value image data is quantized into N-value image data for each pixel, and a dot arrangement pattern corresponding to the gradation value indicated by each quantized pixel is assigned. Finally, ejection data (recording data) corresponding to each nozzle row is generated. The HS processing unit 37 performs clear ink application amount correction (clear HS) processing, which will be described later with reference to FIG. Specifically, the image processing unit 36 performs predetermined color conversion of the image data to obtain the color signal data of the clear ink and the C, M, Y, and K color material inks. Thus, the applied amount correction (HS correction) is performed according to the HS table of each ink. The clear ink color signal is corrected in accordance with an HS table obtained by recording a pattern to be described later with reference to FIG. The image processing unit 36 quantizes the image data composed of the color signal data after the HS correction.

  The host device 100 is a supply source of image data, and can be a computer that creates and processes data such as images related to recording, or may be in the form of a reader unit for image reading. Image data, other commands, status signals, and the like are transmitted / received to / from the controller 9 via the interface (I / F) 100a. The sensor group is a sensor group for detecting the state of the apparatus. The reflective optical sensor 30 described above with reference to FIG. 4, the photocoupler 32 for detecting the home position, and an appropriate temperature sensor for detecting the environmental temperature. A temperature sensor 31 and the like provided at the site are included. The head driver 2a is a driver that drives the recording head 2 according to recording data or the like. The head driver 2a includes a shift register that aligns print data according to the position of the discharge heater, a latch circuit that latches the print data at an appropriate timing, a logic circuit element that operates the discharge heater in synchronization with the drive timing signal, and a print position. There is a timing setting unit for appropriately setting the drive timing (discharge timing) for alignment. The motor driver 16 is a driver that controls driving of the feeding motor 15 and is used to feed a recording medium. The motor driver 12 is a driver that controls the driving of the belt driving motor 11 that moves the conveying belt 5 and is used to convey the recording medium P in the X direction. The motor driver 17 is a driver that controls driving of the carriage of the reflective optical sensor 30. The electric band driver 13 a is used to charge the conveyance belt 5 and to bring the recording medium P into close contact with the conveyance belt 5.

<Color ink and clear ink>
The clear ink is a liquid that does not contain a color material, and its components are those that aggregate or deposit the pigment color material when the color material ink is a pigment ink, and when the color material ink is a dye ink, A pigment is deposited. In the present embodiment, the clear ink contains calcium nitrate tetrahydrate, glycerin, a surfactant, and water, and the color ink is a pigment ink using a pigment as a color material. In the recording medium, when the color material ink lands on the area where the clear ink is applied in advance, the polyvalent metal salt acts on the pigment or dye that is the color material of the color material ink, and the insoluble or hardly soluble metal composite aggregates. Or it precipitates. As a result, the penetration of the coloring material component in the coloring material ink into the recording medium is suppressed, and it tends to remain in the vicinity of the surface layer of the recording medium.

<Applying clear ink>
In this embodiment, when recording an image, clear ink is applied to an area on the recording medium where an image is to be recorded prior to color material ink. Specifically, as shown in FIG. 1, the clear ink recording head 21 located upstream in the conveyance direction of the recording medium P discharges, and then the color material ink recording head 22 located downstream. The above-mentioned application is performed by discharging the respective color material inks. In this embodiment, the amount of clear ink applied is designed so that about 10 ng of clear ink is applied to a pixel having a size equivalent to 600 dpi in both the X and Y directions (FIG. 1). That is, when the clear ink recording duty indicated by the image data is 100%, the amount of clear ink applied to the 600 dpi pixel is designed to be about 10 ng. In this embodiment, since recording is performed on pixels having a density of 1200 dpi in both the X and Y directions, when the recording duty is 100%, one clear ink is applied to each of two pixels of 2 × 2 of 1200 dpi. When dots (clear ink droplets) are recorded (applied), the total of these ink droplets is about 10 ng. In the application amount correction unit 37, when the gradation value indicated by the clear ink image data (color signal data) is 128, this value corresponds to the recording duty of 100%. However, even if the above setting is performed, the ejection amount in the recording head may vary. As a result, for example, when the amount of clear ink applied becomes excessive, running cost decreases due to paper deformation due to excessive moisture, ink bleeding, and excessive consumption of clear ink. On the other hand, if the discharge amount decreases and the clear ink application amount is insufficient, the color material ink is insufficiently aggregated, resulting in a decrease in density and a decrease in image quality. Further, when these states are mixed between nozzles of the same recording head, density unevenness occurs in addition to the above-described adverse effects, and the quality of the recorded image is further deteriorated. On the other hand, in the present embodiment, a clear ink application amount correction (clear ink HS correction) process, which will be described later, is performed to manage the clear ink application amount.

  In the description of the present embodiment, it is assumed that the clear ink uniformly applies a certain amount to the area substantially the same as the image forming area formed by the color material ink. However, as a method of applying the clear ink, the clear ink may be applied to the entire surface of the recording medium regardless of the area where the image is recorded. In addition, the amount of clear ink applied may be variable depending on the amount of color material ink applied in the image recording unit. By doing so, it is possible to further reduce the processing load related to the clear ink application region and to further suppress excessive consumption of the clear ink.

  In the present embodiment, when an image is recorded, the clear ink is applied prior to the color material ink application, but the application order is not limited to this. The clear ink may be applied after the color material ink is applied, or the clear ink may be applied between the application of the plurality of types of color material inks.

<Grant amount correction (HS)>
The processing of the application amount correction processing unit 37 will be specifically described. Here, a description will be given by taking as an example a nozzle row of ink of one color in the recording head 22 of color material ink. FIG. 6 is a diagram illustrating an example of density unevenness caused by a difference in ejection characteristics between nozzles in the nozzle row of the recording head. Note that the recording head of this embodiment is formed by arranging a plurality of head chips provided with nozzles so as to overlap some of the nozzles. At the time of recording by this recording head, the overlapping nozzles are set to be used ½ each by mask processing.

  For each nozzle of one color nozzle row of the recording head, recording is performed with image data of the same signal value (gradation value) in order to record a uniform image of density d0. In this case, for example, the image data is quantized without performing the process of the applied amount correction processing unit 37 to obtain ejection data, and recording is performed by ejecting ink from each nozzle of the one color nozzle row. When the density of the obtained image is optically measured, the density distribution shown in FIG. 6 is obtained. Even when HS correction is performed by the applied amount correction processing unit 37, a density distribution as shown in FIG. 6 may be obtained due to a change with time of the recording head or the like. In the HS correction, such a density distribution is corrected so as to have a uniform density d0 for all nozzles, for example. Specifically, the HS processing unit 37 applies the signal value (gradation value) of the image data corresponding to the nozzle of the chip showing a density value (for example, d1 or d3) higher than the target density d0 shown in FIG. Then, correction is performed to reduce the signal value. On the other hand, for the signal value (gradation value) of the image data corresponding to the nozzle of the chip that shows a density value (for example, d2) lower than the target density d0, a correction for increasing the signal value is performed. That is, the signal level applied to the chip is increased or decreased from the relationship between the discharge characteristic of the chip and the target discharge characteristic. Such data for HS processing for each chip is stored in the ROM 34 as table data.

  As described above, the present embodiment relates to HS correction for correcting the density distribution (density unevenness) between chips. This is because the density distribution is microscopically generated in units of nozzles, but the density distribution between different chips tends to be larger than the density distribution in the same chip due to the chip manufacturing method. . Of course, the present invention can also be applied to a density distribution for each nozzle or a density distribution for each of a plurality of nozzle groups, which will be described later.

<Sensor light source color and reflection density>
Next, the sensor light source color and the reflection density will be described. The reflective optical sensor 30 according to the present embodiment includes red (R light source), green (G light source), light emitting unit 31 according to the clear ink, the color tone of the color material ink, the configuration of the recording head, etc. It is selected from three types of light emitting diodes (LEDs) of blue (B light source).

  FIG. 7 is a diagram showing the color wavelength characteristics of the R, G, and B light emitting diodes used in the light emitting unit 31, and shows the light intensity with respect to the wavelength of each color of the light source. As shown in FIG. 7, in order from the left, blue (B light source) is a wavelength characteristic having a peak wavelength near 470 nm, green (G light source) is a wavelength characteristic having a peak wavelength near 530 nm, and red (R light source) is a peak. It is a wavelength characteristic in which the wavelength is in the vicinity of 620 nm.

  FIGS. 8A to 8D are diagrams for explaining the measurement principle using the optical characteristics of the irradiation light from the light emitting unit 31. FIG. FIG. 8A shows the wavelength characteristics of the R light source among the R, G, and B light sources of the light emitting unit 31. FIG. 8B shows the wavelength characteristic of the reflectance of the recording medium itself on which dots are not formed, and this is due to the color of the recording medium itself in the non-dot-formed part. FIG. 8C shows the wavelength characteristic of the light absorption rate of the recording medium itself, which is obtained by subtracting the above reflectance from 100%. FIG. 8D shows the wavelength characteristics of the light reflected from the recording medium of the light from the R light source, and shows the relationship of the light intensity (reflected light intensity) with respect to the wavelength.

  As shown in FIGS. 8B to 8C, the recording medium used in this embodiment has a high reflectance and a low absorption rate over the entire wavelength in the visible region. Accordingly, the optical characteristic of the reflected light of the light from the R light source shown in FIG. 8D is slightly reduced by the light absorption of the recording medium with respect to the light intensity, but the wavelength characteristic is as shown in FIG. It is almost the same as that of the R light source itself shown in FIG. The shaded portion in FIG. 8D is a portion that contributes to the measurement output of the element that measures the intensity of light having a wavelength in the visible region. Actually, the sensitivity characteristic of the measuring element influences, but in the following, in order to make the explanation easy to understand, the area of the shaded portion is assumed to be the measurement result (reflection density) of the optical sensor as it is. When the shaded area is large, the reflection density is low, and when the shaded area is small, the reflection density is high.

  Next, the relationship between the color tone of the color material ink and the light source color will be described. Hereinafter, a case where an R light source is used as the light source color will be described as an example.

  9 to 12, black (K), cyan (C), magenta (M), and yellow (Y) color material ink dots are formed on a recording medium, and their optical characteristics and optical sensors are used. It is a figure for demonstrating a measurement result. 9A to 12A show the wavelength characteristics of the R light source. FIGS. 9B to 12B show the reflectance of the dot formation portion (recording portion) of each color ink on the recording medium, which is due to the color formation of the dot formation portion by each color ink. (C) in FIGS. 9 to 12 show the absorptance of the dot forming portion of each ink in the recording medium, and is obtained by subtracting the reflectance from 100%. (D) of FIGS. 9-12 has shown the wavelength characteristic of the reflected light of R light source from a recording medium, and this represents the relationship between the wavelength of reflected light, and an intensity | strength.

  For example, in the case of the K ink shown in FIG. 9, the reflectance is low in the entire wavelength region as shown in FIG. 9B, and conversely, the absorptance is in the entire wavelength region as shown in FIG. 9C. I understand that it is expensive. For this reason, in the vicinity of the wavelength of 620 nm, which is a red region, the reflected light intensity of the K dots becomes weak as shown in FIG. 9D, and thus the reflection density becomes high. As a result, the difference becomes larger compared to the reflected light intensity of the white paper portion (of the recording medium) shown in FIG.

  In the case of the C ink shown in FIG. 10, as shown in FIG. 10B, there is a reflectance peak near the wavelength of 460 nm corresponding to the color tone, and conversely, as shown in FIG. It can be seen that the absorptance in the visible region other than the wavelength corresponding to is high. Therefore, in the vicinity of a wavelength of 620 nm, which is a red region, the reflected light intensity of the C dot is weak and the reflection density is high, as shown in FIG. As a result, like the K ink, the difference from the reflected light intensity of the white paper portion is relatively large.

  In the case of M ink and Y ink shown in FIGS. 11 and 12, respectively, the reflectance has wavelength characteristics as shown in FIGS. 11B and 12B, respectively. (C), as shown in FIG. That is, the M ink and the Y ink have low absorptance in the vicinity of a wavelength of 620 nm that is a red region. Accordingly, the reflected light intensities of the M dots and Y dots with respect to the R light source are relatively strong as shown in FIGS. 11D and 12D, respectively, and the reflection density is relatively low. As a result, when compared with the reflected light intensity of the white paper portion shown in FIG. 8D, the difference is small.

  FIGS. 13A to 13E are diagrams for explaining the optical characteristics when the clear ink and the single color ink are recorded in a superimposed manner and when they are recorded without being superimposed. FIG. 13A shows the wavelength characteristics of the R light source in the same manner as the diagram for explaining the optical characteristics described above regarding the color material ink. FIG. 13B shows the wavelength characteristics of the reflectivity of each dot forming portion when the K ink alone and the K ink overlap with the clear ink in the recording medium. Here, in FIG. 13B, the solid line indicates the characteristic when the K ink overlaps the clear ink, and the broken line indicates the characteristic when the K ink is a single color. The same applies to FIGS. 13C and 13D. In FIG. 13A, the reflectivity is lower in the entire wavelength region in the overlapping case indicated by the solid line than in the case of the K ink alone indicated by the broken line. That is, it can be seen that the density of K ink increases by overlapping with clear ink. FIG. 13C shows the wavelength characteristic of the absorptance of the K dot forming portion on the recording medium. This is obtained by subtracting the above reflectance from 100%. FIG. 13D shows the wavelength characteristics of the reflected light from the recording medium under the R light source, and shows the relationship between the wavelength and intensity of the reflected light. FIG. 13E shows a difference in wavelength characteristics (reflected light intensity) of the reflected light shown in FIG. This represents the difference between the wavelength and intensity of the reflected light between the K ink alone and the case where the K ink is superimposed on the clear ink. In the clear ink application amount correction process of the present invention, the difference distribution is used to detect the clear ink application amount distribution. Hereinafter, some embodiments will be described.

(First embodiment)
<Reflection density of the recording area with clear ink and color material ink>
FIG. 14 and FIG. 15 are cross-sectional views of the recording medium for explaining the state of penetration when two color inks having different tones land on the same position of the recording medium. 14A to 14D show the case where the color material ink 1 and the color material ink 2 land on the recording medium in order, and FIGS. 15A to 15F show the clear ink and the color material ink on the recording medium. 1 shows a case where the color material ink 2 has landed in order.

  As shown in FIG. 14A, ink droplets 241 of color material ink 1 are ejected from the recording head. When these ink droplets land on the paper white portion of the recording medium, the solvent contained in the ink penetrates into the recording medium, and the color material, which is a solid content contained in the ink, is fixed on the surface layer of the recording medium. Thereby, as shown in FIG.14 (b), the dot 242 is formed. Subsequently, as shown in FIG. 14C, the color 2 ink droplets 243 ejected from the recording head are ejected. The ink droplets land so as to overlap the dots 242 formed on the recording medium. In this way, when the ink droplets have already landed on the recording medium to form dots, as shown in FIG. 14D, the ink droplets 243 landed later at the same position are already formed dots 242. It penetrates deep into the water and penetrates to the position of the dot 244. This is because the wettability of the recording medium is increased by the ink that has landed first, and the ink easily enters the recording medium. As described above, when inks of two different colors are ejected in an area where there is no clear ink, the ink droplets 243 of the color material ink 2 that land afterward penetrates to the deep part of the recording medium, so that the surface layer of the recording medium The dot 242 of the ink droplet 241 of the color material ink 1 that has landed first remains. As a result, the color of the color material ink 1 is predominantly observed in the portion where the dots overlap. In FIG. 14, the dot 242 and the dot 244 are separately shown to express the permeation position in a simplified manner, but a part of the color material of the ink droplet 243 of the color material ink 2 landed later is also a surface layer. May remain.

  On the other hand, when clear ink and two types of color material ink are used, as shown in FIG. 15A, ink droplets 245 of clear ink are ejected from the recording head. As shown in FIG. 15B, the ink droplets land on the paper white portion of the recording medium, and are then fixed on the surface layer of the recording medium to form dots 246. Next, as shown in FIG. 15C, the ink droplet 247 of the color material ink 1 is ejected from the recording head and landed so as to overlap the clear ink dot 246 formed on the recording medium. The color material ink 1 is aggregated by contact with the clear ink, the solvent contained in the ink penetrates into the inside of the recording medium, and as shown in FIG. 15D, the color material contained in the ink droplet 247 is as shown in FIG. Compared to the case shown, fixing is performed in a region closer to the surface layer of the recording medium, and dots 248 are formed. Subsequently, as shown in FIG. 15E, the ink droplets 249 of the color material ink 2 are ejected from the recording head, and as shown in FIG. 15F, the dots 248 of the color material ink 1 that have landed earlier are formed. Landing to overlap. Since the component of the clear ink dot 246 that landed first remains on the surface layer of the recording medium, the color material of the ink droplet 249 of the color material ink 2 does not penetrate deeply as in the example shown in FIG. Fixing is performed above the dot 248 of the color material ink 1.

  As described above, when two types of color material ink and clear ink are used, the color materials of the color material ink 1 and the color material ink 2 are different from those in the case where the clear ink is not used as shown in FIG. Fixes closer to the surface. As a result, the density of the dot portion is improved, and the color tone of the color material ink 2 fixed to the upper layer portion appears to be dominant.

  FIGS. 16A to 16K are diagrams for explaining the difference in optical characteristics between the case where the clear ink is used and the case where the clear ink is not used as described above with reference to FIGS. ) Shows a case where black (K) ink is used as the color material ink 2. FIGS. 16A, 16 </ b> B, and 16 </ b> C respectively show the wavelength characteristics of the light emitting diodes of the R, G, and B light sources of the light emitting unit 31.

  FIG. 16D shows dots formed when Y ink and K ink overlap in this order (broken line) and when clear ink, Y ink and K ink overlap in this order (solid line) on the recording medium. The wavelength characteristic of the reflectance of the part is shown. In addition, the broken line and the solid line in a figure mean the same thing also in FIG.16 (e)-(h).

  As shown in FIG. 16D, when clear ink is used (solid line), the reflectance is low (reflection density is high) in the entire wavelength region. Further, comparing the presence of clear ink (solid line) and the absence (broken line), it can be seen that the shape of the curve indicating the reflectance in a specific wavelength region changes. As described above with reference to FIGS. 14 and 15, this is due to a change in color tone due to the change in the fixing position relationship between the color material ink 1 and the color material ink 2 in accordance with the presence or absence of the clear ink. Specifically, when clear ink is present, the K ink that has landed later is fixed on the upper layer and becomes a dominant color tone, so that the reflectance is low in all wavelength ranges, and the curve shape is substantially flat. On the other hand, when there is no clear ink, the Y ink that has landed first is fixed on the upper layer and becomes a dominant color tone. For this reason, the reflectivity is relatively low in the region near the wavelength peak of the B light source shown in FIG. 16C, whereas the vicinity of the wavelength peaks of the R and G light sources shown in FIGS. 16A and 16B. In the region of, the reflectance is relatively high. FIG. 16E shows the wavelength characteristic of the absorptance of the dot forming portion in the recording medium. This represents a value obtained by subtracting the reflectance described above from 100%.

  FIGS. 16F, 16G, and 16H show the wavelength characteristics of the reflected light from the dot formation portion of the recording medium under the R, G, and B light sources, respectively. When clear ink is present (solid line), since black has a dominant color tone, the reflected light intensity is weak under any light source, and thus the reflection density is high. On the other hand, when there is no clear ink (broken line), yellow has a dominant color tone, so that the reflected light intensity is high (reflection density is low) under the R and G light sources, but is weak (reflective) under the B light source. The concentration is high). From this point, by selecting R and G light sources that have a relatively low reflection density at the dot forming portion when there is no clear ink, the difference in reflection density between when there is no clear ink and when there is no clear ink can be increased. .

  FIGS. 16 (i), (j), and (k) show differences in wavelength characteristics of reflected light depending on the presence or absence of clear ink under the R, G, and B light sources, respectively. In each figure, the area of the shaded area represents the magnitude of the difference in reflected light intensity, and the R and G light sources are larger in area than the B light source. Since the difference in reflection density is larger as the area is larger, the HS correction pattern detection accuracy is improved.

  In the above example, the case where the clear ink is “present” and the case where the clear ink is “not present” has been described. However, the difference in reflection density between the case where the amount of clear ink applied is “large” and “small” also has an effect of increasing it. . Further, the case where Y ink and K ink are sequentially printed has been described, but the same effect can be obtained by appropriately combining the color tone of the color material ink, the firing order, and the light source color. That is, for a certain light source color, a color tone with a low reflection density is selected as the color material ink 1 that lands first, and a color tone with a high reflection density is selected as the color material ink 2 that lands later. This makes it possible to increase the amount of change in reflection density compared to the case of using one type of color material ink (single color), and to improve the detectability of the difference between when there is clear ink and when there is no clear ink. it can.

<Clear ink application amount correction (Clear ink HS)>
FIG. 17 is a flowchart showing a process for creating a table for clear ink application amount correction (HS) according to the first embodiment of the present invention. As described above, this HS table is used when the application amount correction processing unit 37 (FIG. 5) performs the application amount correction.

  First, a pattern (HS pattern for clear ink) for obtaining a clear ink application amount correction table is recorded (S301). Next, the optical characteristics of the recorded HS pattern are measured (S302). Then, a correction coefficient related to the clear ink application amount is obtained from the measured optical characteristics (S302), and a clear ink application amount correction table is created (S304). Details of each step will be described below.

<S301: HS Pattern Recording for Clear Ink>
The HS pattern for clear ink is recorded using clear ink and two predetermined color material inks. In the present embodiment, yellow (Y) ink is used as the first color material ink, and black (K) ink is used as the second color material ink. FIG. 18 is a diagram illustrating an example of the HS pattern for clear ink according to the present embodiment. The HS pattern for the clear ink includes the first color material ink (Y) and the second color material ink (K) with a constant applied amount for the plurality of inspection patches 61 formed with different applied amounts depending on the clear ink. Are recorded by overlapping each other in order (detection auxiliary pattern 62). FIG. 19 is a flowchart showing a process for recording the HS pattern. First, clear ink is ejected from the recording head 21 to record a plurality of inspection patches 61 (a) to (i) having different application amounts (S401). These inspection patches have 0%, 25%, 50%, 75%, (100%), 125%, centering on the applied amount when the applied amount of clear ink set at that time is 100%. Each of them is formed with a total of nine application amounts of 150%, 175%, and 200%. These patches for each given amount are shown as nine vertical columns 61 (a) to 61 (j) in FIG. Further, these inspection patches are recorded for each chip arranged in the clear ink recording head 21. These are shown as horizontal rows aj in FIG. More specifically, the patches in the patch rows a to j are 512 pixels × 512 pixels (about 108 mm square) using 512 nozzles at the center of each of the chips H200a to H200j arranged in the recording head 21. As recorded. That is, in the present embodiment, the ejection characteristics are detected for each chip, and the application amount correction is performed for each chip based on the detection result. In this respect, the ejection characteristics of the 512 nozzles in the center are treated as representative of the ejection characteristics of the chip. Further, the nozzles used for recording the patch portion with the color material ink by the recording head 22 to be described below are 512 nozzles at the center of each chip similarly to the clear ink. Needless to say, nozzles other than the 512 nozzles in the central portion are used for recording in an area other than the patch. However, if the position of the color material ink recording head 22 in the Y direction is not the same as that of the clear ink recording head 21, the color material ink may use the nozzles other than the central portion to record the patch portion. . Note that the nine given amounts from 0% to 200% are specifically represented by gradation values of 8-bit image data. For example, when the gradation value is 255, a patch is used. This is the amount by which one clear ink dot is formed for each of the above 512 pixels × 512 pixels. For example, when the set amount (tone value) of the clear ink is 128, 0, 32, 64, 96, (128), 160, 192, 224, 255 are centered on this applied amount. It becomes a gradation value.

  Referring to FIG. 19 again, when the inspection patch with the clear ink is recorded as described above, next, the inspection patch recorded as described above with the first color material ink (Y) and the area other than the patch are recorded. On the other hand, the auxiliary detection pattern 62 is overlaid and recorded based on image data of a predetermined application amount (tone value) (S402). Subsequently, with the second color material ink (K), as with the first color material, each of the inspection patches and areas other than the patches are detected based on image data of a predetermined applied amount (tone value). The pattern 62 is overlaid and recorded (S403).

  FIG. 20 is a diagram showing the HS pattern for clear ink and the recording order thereof. As shown in FIG. 20, the inspection patches 61 (a) to (i) are first recorded on the recording medium P using clear ink. Then, a detection assisting pattern 62 (a) using Y ink and a reference pattern 62 (b) using K ink are sequentially recorded on the inspection patch and other regions. In the present embodiment, the detection assist pattern 62 (a) is configured such that about 20 ng of Y ink is applied to an area where the gradation level (applied amount) of image data is equivalent to 600 dpi in length and width, and the detection assist pattern 62 (b). Are solid patterns of uniform density, each applying approximately 20 ng of K ink to an area corresponding to 600 dpi in length and width. This applied amount corresponds to the maximum applied amount (duty) of the color material ink used during recording in the recording apparatus of the present embodiment. In pattern recording, it is desirable to perform clear ink HS after correcting the color material ink application amount in advance in order to reduce the influence of uneven color material ink application amount.

<S302: Optical characteristic measurement>
The optical characteristics of the recorded inspection patches 61 (a) to (i) are measured. After the HS pattern for clear ink is recorded as described above, the recording medium P and the carriage are arranged so that the reflective optical sensor 30 mounted on the carriage is positioned at a position opposite to the inspection patches 61 (a) to (i). Move. Then, the reflection optical density as the optical characteristic of each patch is measured. In the present embodiment, red (R light source) is used as the light source of the reflective optical sensor 30. In order to reduce the influence of noise, the carriage may be stopped to perform measurement, a sensor having a large spot diameter may be used, or measurement results at a plurality of points may be averaged. As a result, it is possible to average the local variation on the recorded pattern and measure the reflection optical density with high accuracy.

<S303: Calculation of a given amount after correction>
FIG. 21 is a diagram illustrating an example of measurement results of the inspection patches 61 (a) to (i) recorded by a certain chip. In FIG. 21, the reflection density D gradually increases from the patch (a) where the application amount of the clear ink is 0% to the patch (e) of 100%, while the reflection after the patch (e) of 100%. The density Dn is substantially constant. This indicates that the minimum clear ink application amount necessary for the aggregation of the color material ink, that is, the appropriate clear ink application amount is about 100% in the chip on which the inspection patch of this example is recorded. Yes. In this embodiment, as a criterion for determining whether or not the reflection density Dn is substantially constant, the applied amount in the patch immediately before the patch whose reflection density change ΔD between inspection patches is less than 3% is cleared for the chip. Set as the post-correction amount of ink. That is, as described above, in the present embodiment, the application amount indicated by the clear ink image data, which is set when the inspection patch is recorded, is set to 100%. For this reason, the application amount 100% corresponding to this chip, which is image data for recording clear ink, is corrected by the application amount correction processing unit 37 (FIG. 5) and is used as it is as the clear ink image with the application amount 100%. It becomes data. When the serial numbers n of the inspection patches 61 (a) to (i) are 1 to 9, and each reflection density measurement value is expressed as Dn, ΔDn is expressed by the following formula.
ΔDn = (ΔDn-1−Dn) / Dn (n = 2, 3, 4,..., 9)
FIG. 22 is a diagram showing the density Dn and the density change amount ΔDn measured in the measurement result chip shown in FIG. As shown in FIG. 22, since the density change amount ΔDn first becomes less than 3% when n = 6, “100%”, which is the applied amount of n = 5 (inspection patch e), is set to be in this example. This is calculated as the corrected amount of clear ink applied to the chip.

  FIG. 23 is a diagram illustrating measurement results of the inspection patches 61 (a) to (i) recorded by a chip different from the measurement result chip illustrated in FIG. As shown in FIG. 23, the reflection density D gradually increases from the patch (a) with 0% clear ink applied to the patch (g) with 150%, whereas the patch (g) with 150%. Thereafter, the reflection density D is substantially constant. This indicates that the appropriate application amount in the chip of this example is about 150%, that is, the application amount is insufficient at the current setting value of 100%. FIG. 24 is a diagram showing the density Dn and density change amount ΔDn measured in the measurement result chip shown in FIG. In FIG. 24, since the change amount ΔDn is less than 3% for the first time because n = 8, “150%”, which is the applied amount of n = 7 (inspection patch g), is set to the clear ink for the chip of this example. It is calculated as the post-correction given amount. That is, the applied amount 100% corresponding to the chip, which is image data for recording clear ink, is corrected by the applied amount correction processing unit 37 (FIG. 5), and the clear ink image data with the applied amount of 150% Become.

  Here, as a comparative example, the measurement value of the inspection patch 61 when the clear ink HS pattern is recorded using only one color (for example, K ink) as the clear ink will be described. FIG. 25 is a flowchart showing a process for recording the HS pattern for clear ink according to the comparative example. In FIG. 25, in step 501, a plurality of inspection patches using clear ink are recorded as in step 401. Next, in step 502, the first color material ink (K) is used to record a predetermined amount of auxiliary detection pattern 62 (b) superimposed on the clear ink test pattern.

  FIG. 26 is a diagram showing the measurement result of the inspection patch recorded by the clear ink chip that obtains the measurement result shown in FIGS. 21 and 22 in accordance with the processing described above with reference to FIG. FIG. 27 is a diagram showing the density Dn and the density variation ΔDn measured in the measurement result chip shown in FIG. As shown in these figures, the difference in density detected between the inspection patches is small. As a result, in the present embodiment, the optical density measured from the inspection patch (f) is constant (see FIGS. 21 and 22), and in this comparative example, the patch (b) with an applied amount of 25%. Thereafter, the reflection density D is substantially constant. Thus, it can be seen that the detection accuracy of the applied amount at which the concentration is substantially constant is lower than that in the embodiment described above.

  Similarly, FIG. 28 is a diagram showing the measurement results of the inspection patch recorded by the clear ink chip that can obtain the measurement results shown in FIGS. 23 and 24 in accordance with the processing described above with reference to FIG. FIG. 29 is a diagram showing the density Dn and the density change amount ΔDn measured in the measurement result chip shown in FIG. Also in this comparative example, the difference in density detected between the inspection patches is small. As a result, in the present embodiment, the optical density measured from the inspection patch (h) is constant (see FIGS. 23 and 24), and in this comparative example, the patch (b) with an applied amount of 25%. Thereafter, the reflection density D is substantially constant. Also in this example, it can be seen that, compared with the above-described embodiment, the detection accuracy of the applied amount at which the density becomes substantially constant is lowered.

  As described above, according to the present embodiment, by appropriately combining the combination of the two color material inks, the recording order, and the light source color used for measurement, detection between inspection patches when the clear ink is large and when the clear ink is small is detected. The difference in values can be increased, and the detection performance can be improved.

<S304: Generation of Clear Ink Amount Correction Table, Set Amount after Correction>
As described above, a clear ink application amount correction table is generated for each chip so as to realize the corrected application amount calculated in step 303. Specifically, for the chip from which the measurement result shown in FIG. 21 is obtained, the gradation value (applied amount) 100% of the clear ink image data corresponding to the nozzle of the chip is set to 100% / 100% = The table is converted to a gradation value multiplied by a coefficient of 1.0. For the chip from which the measurement result shown in FIG. 23 is obtained, the gradation value (applied amount) 100% of the clear ink image data corresponding to the nozzle of the chip is set to a coefficient of 150% / 100% = 1.5. The table is converted to a gradation value multiplied by. The clear ink HS table thus obtained is stored in the ROM 34 (FIG. 5). At the time of recording using clear ink, the CPU 33 requests that the HS table for clear ink stored in the ROM 34 be transmitted to the application amount correction processing unit 37. The applied amount correction processing unit 37 corrects the clear ink image data using the transmitted HS table. By this control, it is possible to reduce the variation in the ejection characteristics of the ink due to the manufacturing error of the clear ink in units of chips, the deterioration of durability, and the like, and uniform application can be performed.

<Combination of sensor light source color and detection auxiliary ink color>
In the description of the above-described embodiment, a red (R) light source is used as the light source color, and among the color material inks, Y ink is used as the detection auxiliary color material ink to be applied first to the recording medium, and the detection auxiliary color is applied later. K ink is used as the material ink, but there are combinations that can obtain the same effect in other combinations. As described above, according to the present invention, as the first colorant ink for detection assistance to be applied first to the light source color used for inspection, the detection assistance to which ink having a color tone having a low reflection density is applied later is used. As the second color material ink, an ink having a color tone with a high reflection density is selected. As a typical combination, assuming that R, G, and B as sensor light source colors and C, M, Y, and K as color material inks are ideal colors, detection assistance is performed under a red (R) light source. Y ink or M ink can be selected as the first color material ink, and K ink or C ink can be selected as the second color material ink for detection assistance. Under a green (G) light source, C ink or Y ink can be selected as the first color material ink, and K ink or M ink can be selected as the second color material ink. Further, under the blue (B) light source, the first color material ink can be selected by combining M ink or C ink, and the second color material ink can be selected by combining K ink or Y ink. . Note that color inks such as C, M, Y, and K used in an ink jet recording apparatus are often not ideal colors such as C, M, Y, and K, and color developability depends on the recording medium used. There are also restrictions on the dot overlap order depending on the configuration of the printing apparatus. From this point, it is desirable to obtain an optimum combination in advance by actually recording a pattern while changing the above conditions on a recording medium used for recording.

<Detection of optical characteristics>
In the description of the above-described embodiment, as a detector that detects optical characteristics, a reflective light source that irradiates a colored light source having a specific peak wavelength such as R, G, and B and measures the reflected light intensity (reflection density). Although a sensor is used, other detectors may be used as long as they are detectors that detect optical characteristics in a specific wavelength region. For example, RGB information can also be acquired by irradiating white light from a white light source, spectrally separating the amplified reflected light by each RGB color filter, and reading it with a CCD sensor as an image sensor. Moreover, RGB information can also be acquired by reading the reflected light by each RGB light source with the CMOS sensor which is an image pick-up element. In these cases, the same effect can be obtained by replacing the luminance value in an appropriate channel in the acquired RGB information with the reflection density described above.

  In another embodiment, when visual inspection is performed, a reference color that is later applied with a color tone ink having a low reflection density due to white light (high lightness) as a detection auxiliary color material ink to be applied first. As the material ink, an ink having a color tone with a high reflection density by white light (low brightness) is selected. Thereby, the difference in reflection density (brightness) can be increased between the case where the clear ink is large and the case where the clear patch is small. Then, the user observes the clear HS pattern recorded as described above as shown in FIG. 18, selects a patch having a constant density from the nine patches, and sets the applied amount in the patch to the clear ink. It can be input as the amount of grant. As an example of a specific combination of inks, Y ink is used as the first color material ink for assisting detection, and K ink is used as the second color material ink for assisting detection.

(Second Embodiment)
In the second embodiment of the present invention, a line scanner capable of detection corresponding to the width of a recording medium is used as a reading device for detecting optical characteristics. The line scanner in this embodiment is composed of a CCD line sensor, and CCD sensors are arranged at intervals of 1600 dpi in a direction perpendicular to the recording medium conveyance direction. By using such a relatively high resolution reading apparatus, it is possible to correct the applied amount for every several nozzles.

  FIG. 30 is a cross-sectional view showing a line scanner used in the present embodiment. In FIG. 30, a CCD 40 converts light into an electrical signal. The reflected light beam 42 from the document passes through the lens 41 and reaches the CCD 40. In this configuration, 43 is a mirror for folding the light beam 42 into a narrow space, 44 is a document illumination device for illuminating the document, 45 is a transport roller for transporting the document, 46 is a paper transport guide plate for guiding the document, Respectively. The document guided by the paper transport guide plate 46 passes through the reading unit at a predetermined speed by the transport roller 45. The document on the reading unit is illuminated by the document illumination device 44. The illuminated original light 42 is folded back by a mirror 43, passes through a lens 41, and is collected on a CCD 40. The image information converted into an electrical signal by the CCD 40 is passed to the image analysis unit and analyzed. According to this scanner, analog luminance data of red (R), green (G), and blue (B) channels can be acquired. These luminance data can be handled in the same manner as the reflection densities by the R, G, and B light sources described in the first embodiment.

  FIG. 31 is a diagram showing an HS pattern for clear ink according to the present embodiment. The process for creating the HS table for clear ink in the present embodiment is the same as in the first embodiment described above. The clear ink HS pattern (hereinafter referred to as HS pattern 2) of the present embodiment forms a plurality of inspection patches 63 (a) to (i) with different application amounts of clear ink. Then, the first color material ink (Y) and the second color material ink (K) are sequentially overlapped and formed on these inspection patches in a constant application amount (detection auxiliary pattern 62). The In the same way as described above in the first embodiment, the inspection patches 63 (a) to 63 (i) are 0% centering on the applied amount when the applied amount of clear ink set at that time is 100%. , 25%, 50%, 75%, (100%), 125%, 150%, 175%, and 200%. The clear ink patch 63 is a pattern having a size substantially the same as the width of the recording medium, which is recorded using all the nozzles of each chip.

  FIG. 32 is a flowchart showing processing for recording the HS pattern for clear ink according to the present embodiment. First, a plurality of inspection patches 63 (a) to (i) having different application amounts are recorded by the clear ink recording head 21 (S601). These inspection patches are each formed with nine types of application amounts as described above. Next, the uniform detection auxiliary pattern 62 is superimposed and recorded on the plurality of inspection patches with the first color material ink (Y) (S602). Subsequently, the uniform detection auxiliary pattern 62 is sequentially overlapped and recorded on the plurality of inspection patches 63 by the second color material ink (K) (S603).

  FIG. 33 is a diagram showing the measurement results of the reflection densities of the inspection patches 63 (a), (e), and (i) according to the present embodiment. In the present embodiment, luminance data is acquired at a resolution of 400 dpi by the above-described line scanner. By using a reading device with a relatively high resolution in this way, it is possible to detect the density in finer units. After the reflection density measurement, as in the first embodiment, the density measurement values 63 (a) to (i) are compared for each 400 dpi area, and the corrected application amount of the clear ink is determined.

21, 22 Recording head 30 Reflective optical sensor 31 Light emitting part 32 Light receiving part 33 CPU
34 ROM
35 RAM
37 Application amount correction processing unit P Recording medium H200a to j Recording chip

Claims (10)

Clear having a color material ink recording head for ejecting a plurality of color material inks of different color material types and a nozzle row in which a plurality of nozzles for ejecting a clear ink not containing a color material are arranged An inkjet recording apparatus capable of recording a correction pattern for correcting the amount of clear ink applied when recording on a recording medium using an ink recording head,
Of the plurality of color material inks, a recording portion recorded by the first color material ink and the second color material ink, and each of the plurality of recording portions recorded by the clear ink and having different application amounts. Recording means for recording the correction pattern having overlapping portions on a recording medium;
When the correction pattern is recorded, the color ink recording head and the clear ink recording head are recorded in the order of the clear ink, the first color material ink, and the second color material ink. And control means for controlling the movement of the recording medium;
An ink jet recording apparatus comprising:   The inkjet recording apparatus according to claim 1, wherein the second color material ink is an ink that is fixed on an upper layer of the first color material ink that has been previously recorded on a recording medium. A light source for irradiating the correction pattern;
Detecting means for detecting optical characteristics of the correction pattern based on reflected light from the correction pattern irradiated by the light source;
Further comprising
3. The inkjet according to claim 1, wherein the density of the recording portion by the first color material ink detected by the detection unit is lower than the density of the recording portion by the second color material ink. Recording device.   4. The clear ink recording head includes a plurality of recording chips each having a plurality of nozzles arranged thereon, and records the correction pattern for each recording chip. The ink jet recording apparatus described.   The inkjet recording apparatus according to claim 3, wherein the correction pattern is recorded for each width wider than the reading resolution of the detection unit.   4. The light source according to claim 3, wherein the light source is a red light source, the first color material ink is yellow ink or magenta ink, and the second color material ink is cyan ink or black ink. Inkjet recording apparatus.   The light source is a green light source, the first color material ink is a cyan ink or a yellow ink, and the second color material ink is a magenta ink or a black ink. Inkjet recording apparatus.   4. The light source according to claim 3, wherein the light source is a blue light source, the first color material ink is magenta ink or cyan ink, and the second color material ink is yellow ink or black ink. Inkjet recording apparatus.   9. The inkjet recording apparatus according to claim 1, wherein the brightness of the recording unit using the first color material ink is higher than the brightness of the recording unit using the second color material ink. . Clear having a color material ink recording head for ejecting a plurality of color material inks of different color material types and a nozzle row in which a plurality of nozzles for ejecting a clear ink not containing a color material are arranged A recording method of a correction pattern for correcting the application amount of the clear ink when recording on a recording medium using an ink recording head,
Of the plurality of color material inks, a recording portion recorded by the first color material ink and the second color material ink, and each of the plurality of recording portions recorded by the clear ink and having different application amounts. A recording step of recording the correction pattern having overlapping portions on a recording medium,
In the recording step, when the correction pattern is recorded, the clear ink, the first color material ink, and the second color material ink are recorded in this order. Pattern recording method.