Image processing apparatus, image processing program, and image forming apparatus

Abstract

To make it possible to calculate a correct correction value of a color variation in an image formation apparatus and improve the image quality by correcting the color variation of an image with the correction value and performing image formation.SOLUTION: An image formation control unit controls an image formation unit so as to form an image based on drawing data. A reading unit controls the reading unit so as to perform reading of the image formed by the image formation control unit. A reading variation amount generation unit generates a reading variation amount of a reference image corresponding to a ratio of a read value of the maximum reference image being the image of the maximum pixel value to a read value of the reference image being the image of drawing data among the images of the drawing data. An addition image generation unit generates an addition image obtained by adding the reading variation amount of the reference image to the reference image. A color variation correction amount generation unit generates a color variation correction amount used for color variation correction in the image formation by subtracting the addition image from the read image formed by the image formation unit and read by the reading unit and supplies the color variation correction amount to the image formation control unit.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to an image processing apparatus, an image processing program, and an image forming apparatus.

Background Art

[0002] In an image reading apparatus, when reading a printed matter of a document image, there is a problem that the reflected light of the light irradiated on the document is diffusely reflected in the image reading apparatus, and the level of the target pixel signal increases depending on the peripheral pixel structure in the imaging region (white flare phenomenon). For this reason, a technique for preventing the white flare phenomenon by determining a correction value for the amplified signal based on the read image is known.

[0003] Further, Patent Document 1 (Japanese Patent Application Laid-Open No. 11-355636) discloses an imaging apparatus that electrically corrects and reduces flare to make the screen easier to view. In the case of this imaging apparatus, reference flare generated by a light source whose imaging result becomes a predetermined brightness according to the aperture value and focal length parameters of the optical system is stored in advance in a flare data memory. Then, a state setting circuit detects a video portion having a value larger than a predetermined value from the video signal, estimates the brightness, and when there is a light source having the estimated brightness, flares generated are pseudo-generated as predicted flares using the reference flare, and subtracted from the video signal by a subtractor. Thereby, flare can be reduced.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional image reading apparatus, the amount of change in the read value is calculated from the read image. In the read image, both the change generated in the image reading apparatus and the change generated in the image forming apparatus are imparted. When the amount of read variation is estimated from such a read image and the correction value for the color variation is calculated, the correction value is calculated in a state including unnecessary variation caused by the image forming apparatus. For this reason, there has been a problem that the color variation of the image is corrected with an inaccurate correction value, which affects the image quality.

[0005] The present invention has been made in view of the above-described problems, and an object thereof is to provide an image processing apparatus, an image processing program, and an image forming apparatus capable of calculating an accurate correction value for color variation and improving image quality by correcting the color variation of an image with this correction value.

Means for Solving the Problems

[0006] In order to solve the above-described problems and achieve the object, the present invention includes an image formation control unit that controls an image formation unit to form an image based on drawing data, a reading control unit that controls a reading unit to read the image formed by the image formation control unit, a reading variation amount generation unit that generates a reading variation amount of a reference image corresponding to a ratio between a reading value of a maximum reference image that is an image with the maximum pixel value among the images of the drawing data and a reading value of a reference image that is an image of the drawing data, an addition image generation unit that generates an addition image obtained by adding the reading variation amount of the reference image to the reference image, and a color variation correction amount generation unit that generates a color variation correction amount used for color variation correction during image formation by subtracting the addition image from a read image formed by the image formation unit and read by the reading unit, and supplies the color variation correction amount to the image formation control unit.

Effects of the Invention

[0007] According to the present invention, an accurate correction value for color variation can be calculated, and the color variation of the image can be corrected with this correction value, thereby achieving the effect of improving image quality.

Brief Description of the Drawings

[0008]

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Figure 16

[0009] Hereinafter, a printing system according to an embodiment will be described with reference to the accompanying drawings.

[0010] [First Embodiment] (System Configuration) FIG. 1 is a diagram showing the system configuration of the printing system according to the first embodiment. In FIG. 1, the printing system according to the first embodiment includes a client personal computer device (client PC) 101, a digital front end (DFE) 102, an image forming apparatus 103, and a management server 104.

[0011] The client PC 101 includes an input device such as a mouse device and a keyboard device in addition to a display unit such as a liquid crystal display. The client PC 101 creates a print job such as an image to be printed and transmits it to the DFE 102 or the management server 104.

[0012] The DFE 102 receives a print job from the client PC 101 or the management server 104, creates drawing data by a RIP (Raster Image Processor) engine based on the received print job, and transmits it to the image forming apparatus 103.

[0013] The image forming apparatus 103 performs an image forming operation based on the drawing data received from the DFE 102.

[0014] The management server 104 manages the print jobs received from the client PC 101. Also, upon request from the DFE 102, it transmits the print jobs to the DFE 102.

[0015] (Hardware Configuration of the Image Forming Apparatus) Figure 2 is a diagram showing the hardware configuration of the image forming apparatus 103. As shown in this Figure 2, the image forming apparatus 103 includes a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access memory) 303, an HDD (Hard Disc Drive) 304, an interface (I / F) 305, an image forming unit 306, and a reading unit 307. Note that the HDD 304 may be another storage device such as an SSD (Solid State Drive).

[0016] The CPU 301 uses the RAM 303 as a work area and executes the programs stored in the ROM 302. The HDD (or SSD) 304 is used as a storage unit and stores predetermined setting values and programs. Although it is an example, in the case of the printing system of the first embodiment, a reading variation correction program is stored in this HDD 304. The CPU 301 calculates correction values for color variation correction by executing this reading variation correction program, and performs color variation correction of the image.

[0017] The I / F 305 is connected to the DFE 102, the client PC 101, and the management server 104. The I / F 305 is an interface that enables communication between the DFE 102, the client PC 101, and the management server 104, and the image forming apparatus 103.

[0018] (Configuration of the Image Forming Unit) FIG. 3 is a diagram showing a schematic configuration and a positional relationship of an image forming unit 306 and a reading unit 307 in an image forming apparatus. Although it is an example, in the case of the printing system of this first embodiment, as the image forming apparatus 103, a so-called electronic type image forming apparatus is provided. In this electronic type image forming apparatus, as shown in FIG. 3, the image forming unit 306 has a configuration in which photosensitive drums 403Y (yellow), 403M (magenta), 403C (cyan), and 403K (black) of respective colors are arranged along an intermediate transfer belt 402. Such an image forming unit 306 is an image forming unit called a so-called tandem type (hereinafter, generally referred to as the photosensitive drum 403).

[0019] That is, along the intermediate transfer belt 402 on which an intermediate transfer image for transferring to a sheet fed from a paper feed tray 400 and conveyed by a conveyance roller 401 is formed, the photosensitive drums 403Y, 403M, 403C, and 403K are arranged in order from the upstream side in the conveyance direction of the intermediate transfer belt 402.

[0020] Images of respective colors developed with toner on the surfaces of the photosensitive drums 403 of respective colors are superimposed and transferred onto the intermediate transfer belt 402, thereby forming a full-color image. The full-color image thus formed on the intermediate transfer belt 402 is transferred onto the paper surface of the sheet conveyed on the path by the function of a transfer roller 404 at a position closest to the sheet conveyance path indicated by a broken line in the figure.

[0021] The sheet on which the image is formed on the paper surface is further conveyed, and the image is fixed (image formation) by a fixing roller 405. When performing double-sided printing, after forming an image on the front surface, the sheet is conveyed to a reverse path 407 in the conveyance path, the front and back are reversed, and then conveyed again to the position of the transfer roller 404.

[0022] The reading unit 307 is composed of in-line sensors 406a and 406b (hereinafter generally referred to as in-line sensor 406). The in-line sensor 406 reads both sides of the paper by the fixing roller 405 to obtain read image data of the image fixed on the paper. Note that it is not necessarily required to have two (406a, 406b) in-line sensors 406, and either one of them may be sufficient. For example, when only one sensor 406a is provided, the front surface is read by the sensor 406a when printing, then the back surface is printed, and printing is performed as it is.

[0023] (Software Configuration of Image Forming Apparatus) FIG. 4 is a functional block diagram of each function realized by the CPU 301 of the image forming apparatus 103 by executing a reading variation correction program stored in a storage unit such as the HDD 304. By executing the reading variation correction program, the CPU 301 realizes each function of the printer control unit 601, the reference image generation unit 602, the reading variation generation unit 603, the image formation control unit 604, the printed image reading unit 605, the image comparison unit 606, and the color variation correction amount generation unit 607 as shown in FIG. 4.

[0024] Note that the printer control unit 601 to the color variation correction amount generation unit 607 shown in FIG. 4 are realized by software by the reading variation correction program. However, all or part of these may be realized by hardware such as an IC (Integrated Circuit).

[0025] Further, the reading variation correction program may be recorded and provided on a recording medium readable by a computer device such as a CD-ROM or a flexible disk (FD) in the form of an installable file or an executable file. Further, the reading variation correction program may be recorded and provided on a recording medium readable by a computer device such as a CD-R, a DVD (Digital Versatile Disk), a Blu-ray (registered trademark) disk, or a semiconductor memory. Further, the reading variation correction program may be provided in a form that can be installed via a network such as the Internet. Further, the reading variation correction program may be provided by being pre-installed in a ROM or the like in the device.

[0026] The printer control unit 601 acquires the document image (RIP image: CMYK values) from the DFE 102. The reference image generation unit 602 generates a reference image (Fig. 6(a)) in RGB values of R (red), G (green), and B (blue) by converting the document image supplied in CMYK values based on a predetermined conversion table. Further, the reference image generation unit 602 supplies the reading value (RGB values) of the maximum reference image generated by reading, by the reading unit 307, a portion where no printing such as a dedicated chart is performed (the white portion of the paper) to the reading variation generation unit 603.

[0027] Based on the characteristics of the image forming apparatus 103, the maximum reading image that becomes the maximum observed value can be calculated. The reading variation generation unit 603 calculates the reading variation added to the maximum reference image from the reading variation correction calculation of the maximum reading image. The reading variation generation unit 603 calculates the reading variation of the reference image by reflecting the difference (ratio) between the reading value of the maximum reference image supplied from the reference image generation unit 602 and the reading value of the reference image with respect to the reading variation of the maximum reference image (Fig. 6(d)). Further, the reading variation generation unit 603 generates a reference image (Fig. 6(e)) to which this reading variation is added. The reference image to which the reading variation is added is an example of an added image. Further, the reading variation generation unit 603 is an example of a reading variation generation unit and an added image generation unit.

[0028] The image formation control unit 604 controls the image formation unit 306 to form a printed image (Fig. 6(b)) so as to perform printing based on the rendering data (RIP image: CMYK values) from the DFE 102 acquired by the printer control unit 601. The printed image has the amount of variation on the image formation side superimposed thereon. The printed image reading unit 605 controls the above-described in-line sensor 406 to read the printed image on which the amount of variation on the image formation side is superimposed. Thereby, a read image (Fig. 6(c)) of RGB values is generated. The amount of variation on the image reading side is further superimposed on this read image. For this reason, both the amount of variation on the image formation side and the amount of variation on the image reading side are superimposed on the read image.

[0029] The image comparison unit 606 generates the amount of variation on the image formation side that is superimposed when the image formation control unit 604 forms a printed image by subtracting the reference image on which the read variation amount generated by the read variation amount generation unit 603 is superimposed from the read image on which both the amount of variation on the image formation side and the amount of variation on the image reading side are superimposed.

[0030] The color variation correction amount generation unit 607 converts the amount of variation on the image formation side supplied from the image comparison unit 606 in RGB values into CMYK values and supplies it to the image formation control unit 604 as the color variation correction amount. The image formation control unit 604 performs color correction based on this color variation correction amount and then prints the original image from the printer control unit 601. Thereby, it is possible to prevent the inconvenience of correcting even the amount of variation on the image reading side that was not originally superimposed, and to correct only the amount of variation superimposed on the image formation side to perform image printing. For this reason, it is possible to improve the image quality.

[0031] (Operation of generating read variation amount) Fig. 5 is a flowchart showing the flow of the operation of generating the read variation amount in the read variation amount generation unit 603 of Fig. 4. In step S1, the printer control unit 601 acquires the original image from the DFE 102 and supplies it to the reference image generation unit 602 and the image formation control unit 604.

[0032] In step S2, the reference image generation unit 602 converts the original image supplied with CMYK values into a reference image with RGB values based on a predetermined conversion table. Also, in this step S2, the reference image generation unit 602 generates a paper white value which is the RGB value of the paper white portion of the original image, and supplies it to the reading variation amount generation unit 603.

[0033] In step S3, the reading variation amount generation unit 603 determines whether the maximum reading variation amount, which is the reading variation amount of the paper white portion, has been calculated. If the maximum reading variation amount has not been calculated (step S3: No), the reading variation amount generation unit 603 calculates the maximum reading variation amount based on the paper white value in step S4.

[0034] FIG. 7 shows the position (main scanning position) of each pixel in the main scanning direction, which is the direction in which the pixels of the in-line sensor 406 are arranged, on the horizontal axis, and shows the flare amount on the vertical axis. That is, the vertical axis shows the reading variation amount for each main scanning position. In this FIG. 7, among the pixels arranged in the main scanning direction, if the pixel located at the center is defined as the target pixel, it can be seen that the reading variation amount of this target pixel is the largest, and subsequently, the closer the pixel is to the target pixel, the larger the reading variation amount becomes.

[0035] Next, FIG. 8(a) shows the reading value (white level) of the maximum reading image, which is the maximum value of the observed values, calculated based on the characteristics of the reading unit 307. Also, FIG. 8(b) shows the reading variation amount superimposed on the maximum reading image, calculated based on the reading value of the maximum reading image. On the other hand, FIG. 8(c) shows the reading value (white level) of the maximum reference image, which is the reading value of the paper white portion of the reference image generated by the reference image generation unit 602, and FIG. 8(d) shows the reading variation amount superimposed on this maximum reference image.

[0036] The reading value of the maximum reading image shown in FIG. 8(a) and the reading value of the maximum reference image shown in FIG. 8(c) are each the reading value (maximum reading value) of the white level. Therefore, the reading variation amounts (FIGS. 8(b) and 8(d)) superimposed on the maximum reading image shown in FIG. 8(a) and the maximum reference image shown in FIG. 8(c) should match.

[0037] Therefore, the ratio of the reading value of the maximum reference image shown in Fig. 9(a) to the reading value of the reference image shown in Fig. 9(c) is equal to the ratio of the reading variation amount of the maximum reference image shown in Fig. 9(b) to the reading variation amount of the reference image shown in Fig. 9(d). That is, in the case of the examples shown in Fig. 9(a) and Fig. 9(c), there exists a portion ( = black level portion) that is recessed in the rectangular shape shown in Fig. 9(c) between the reading value of the maximum reference image and the reading value of the reference image as the "difference" between the two. In this case, there also exists a "difference" in the reading variation amount corresponding to the above-mentioned portion recessed in the rectangular shape (see Fig. 9(c)) between the reading variation amount of the maximum reference image and the reading variation amount of the reference image shown in Fig. 9(b) and Fig. 9(d).

[0038] Based on the above, in step S5 of the flowchart in Fig. 5, as shown in Figs. 10(c) and 10(d), the reading variation amount generation unit 603 multiplies the ratio of the reading value of the maximum reference image to the reading value of the reference image by the reading variation amount of the maximum reference image shown in Fig. 10(b). Thereby, the reading variation amount (Fig. 10(a)) superimposed on the reference image can be calculated.

[0039] The reading variation amount generation unit 603 adds the thus calculated reading variation amount superimposed on the reference image to the reference image in step S6 and supplies it to the image comparison unit 606. Thereby, the generation operation of the reading variation amount shown in the flowchart of Fig. 5 is completed.

[0040] The image comparison unit 606 subtracts the reference image with the calculated reading variation amount superimposed thereon from the reading image on which both the variation amount on the image formation side and the variation amount at the time of image reading are superimposed by being printed by the image formation control unit 604 and read by the printed image reading unit 605. Thereby, the color variation correction amount, which is the variation amount superimposed at the time of image formation, can be calculated. This color variation correction amount is calculated for each printed image and supplied to the image formation control unit 604. Thereby, for each printed image, the color variation superimposed at the time of printing can be accurately corrected, and a printed image with good image quality can be obtained.

[0041] (Effect of the First Embodiment) As is clear from the above description, the printing system according to the first embodiment calculates the reading variation amount of the reference image by multiplying the ratio between the reading value of the maximum reference image (the white part of the paper) and the reading value of the reference image for printing by the reading variation amount of the maximum reference image. Then, the calculated reading variation amount of the reference image is added to the reference image. The reference image to which this reading variation amount is added is printed by the image forming control unit 604 and read by the printed image reading unit 605, and then subtracted from the reading image in which both the variation amount at the time of image formation and the variation amount at the time of image reading are superimposed, thereby generating a color variation correction amount in which only the variation amount at the time of image formation is extracted. Then, the color variation of the printed image printed by the image forming control unit 604 is corrected with this color variation correction amount. As a result, the color variation that overlaps at the time of printing can be accurately corrected, and a printed image with good image quality can be obtained.

[0042] [Second Embodiment] Next, the printing system according to the second embodiment will be described. The printing system according to the first embodiment described above performs reading variation amount correction processing on the reading image obtained by printing and reading the original image in the image forming apparatus 103. When performing the reading variation amount correction processing, in order to grasp the reading variation tendency, the reading variation amount is detected based on the reading image of the reference chart printed in advance.

[0043] Here, the reading variation amount on the reading image differs for each image forming apparatus 103 and for each paper type. Therefore, in the printing system according to the second embodiment, the reading variation amount and the paper type information are associated and stored in a storage unit such as the HDD 304. Then, when printing is performed with the same image forming apparatus and the same paper type, the previously detected reading variation amount is reused. As a result, when printing again on paper of the same paper type, the troublesome operation of acquiring the reading variation amount again can be omitted. Note that only this point is different between the first embodiment described above and the second embodiment described below. Therefore, hereinafter, only the difference between the two will be described, and duplicate descriptions will be omitted.

[0044] (Storage Operation of Reading Variation Amount Corresponding to Paper Type) In the case of this second embodiment, in the image forming apparatus 103, the reading variation amount for each paper type is detected in advance and stored in a storage unit such as the HDD 304. FIG. 11 is a functional block diagram of each function for storing the reading variation amount corresponding to the paper type, which is realized by the CPU 301 of the image forming apparatus 103 executing the reading variation amount correction program stored in the HDD 304. Further, FIG. 12 is a flowchart showing the flow of the storage operation (reading variation amount acquisition mode) of the reading variation amount corresponding to the paper type, which is executed by the CPU 301 of the image forming apparatus 103 based on the reading variation amount correction program stored in the HDD 304.

[0045] In FIGS. 11 and 12, when the "reading variation amount acquisition mode" is specified by the user, in step S11, a chart image for printing a predetermined chart is supplied from the DFE 102 to the printer control unit 601. The printer control unit 601 controls the printing of this chart image via the image forming control unit 604.

[0046] In step S12, the printed image reading unit 605 reads the printed chart image, and the reading characteristic generation unit 650 detects the reading variation amount (reading characteristic) based on the read image of the chart image and supplies it to the reading characteristic storage control unit 651.

[0047] In step S13, the reading characteristic storage control unit 651 acquires the paper type information indicating the paper type of the paper on which the chart image is printed from the printer control unit 601. Then, the reading characteristic storage control unit 651 stores the paper type information and the reading variation amount corresponding to the paper type in association with each other in a storage unit such as the HDD 304. Such a storage operation of the reading variation amount corresponding to the paper type is executed for each paper type. As a result, a reading characteristic table 350 in which the reading variation amount (reading characteristic) for each paper of the image forming apparatus 103 is recorded is formed in the HDD 304.

[0048] FIG. 13 is a schematic diagram of a reading characteristic table 350. Among these, FIG. 13(a) is a diagram showing an overview of the reading characteristic table 350, and FIG. 13(b) is a diagram showing an example of a data storage form of the reading characteristic table 350. First, as shown in FIG. 13(a), in the reading characteristic table 350, paper type information (first paper type information, second paper type information, etc.) for each paper type and reading variation amount information (first reading characteristic, second reading characteristic, etc.) corresponding to the paper type are stored in association with each other.

[0049] As the paper type information, as shown in FIG. 13(b), paper identification information (paper ID) such as Y0001 or Y0002, which is uniquely assigned to the paper type, and information indicating the paper type such as plain paper, glossy paper, or matte paper are stored in the reading characteristic table 350. Further, as the reading variation amount (reading characteristic), as shown in FIG. 13(b), a reading value of an 8-bit reading image such as 255 is stored in the reading characteristic table 350.

[0050] When the reading variation amount acquisition mode for the same paper type is executed again, the paper type information and reading variation amount information obtained thereby are overwritten in the reading characteristic table 350 (the previous reading variation amount information is updated to the new reading variation amount information).

[0051] Also, the system side may manage the paper type name, job name, etc. for each paper ID. Thereby, for the reading characteristic table 350, it is only necessary to store the paper ID and the reading value of the reading image, and the storage of the paper type name, job name, etc. in the reading characteristic table 350 can be omitted.

[0052] (Color variation correction operation) Next, the color variation correction operation of the printing system according to the second embodiment, which is performed using such a reading characteristic table 350, will be described. FIG. 14 is a functional block diagram of each function realized by the CPU 301 of the image forming apparatus 103 executing a reading variation amount correction program stored in a storage unit such as the HDD 304. FIG. 15 is a flowchart showing the flow of the color variation correction operation performed using the reading characteristic table 350 when the CPU 301 of the image forming apparatus 103 executes the reading variation amount correction program.

[0053] In FIGS. 14 and 15, in step S21, the printer control unit 601 acquires a RIP image of the document to be printed from the DFE 102. In step S22, the printer control unit 601 gives a print instruction for the RIP image to the image forming control unit 604. As a result, in step S23, the print control of the RIP image is performed by the image forming control unit 604.

[0054] Next, in step S24, the reference image generation unit 602 acquires paper type information indicating the type of paper to be used for the upcoming printing, together with the RIP image, from the printer control unit 601. Then, the reference image generation unit 602 converts the PIP image into a reference image expressed in the RGB space, and supplies it to the reading variation amount correction unit 603a together with the paper type information.

[0055] Next, in step S25, the printed image reading unit 605 supplies a read image obtained by reading the printed image printed under the control of the image forming control unit 604 to the reading variation amount correction unit 603b.

[0056] In step S26, the reading characteristic storage control unit 651 acquires reading variation amount information associated with the paper type information supplied from the reading variation amount correction unit 603a from the reading characteristic table 350 (see FIGS. 11 to 13). Then, the reading characteristic storage control unit 651 supplies the reading variation amount information associated with the acquired paper type information to the reading variation amount correction unit 603a and the reading variation amount correction unit 603b.

[0057] In step S27, the reading variation amount correction unit 603a corrects the reading variation amount of the reference image based on the reading variation amount information corresponding to the paper type information supplied from the reading characteristic storage control unit 651, generates a corrected reference image, and supplies it to the image comparison unit 606. Also in step S27, the reading variation amount correction unit 603b generates a corrected read image in which the reading variation amount of the read image is corrected based on the reading variation amount information corresponding to the paper type information supplied from the reading characteristic storage control unit 651, and supplies it to the image comparison unit 606. In step S28, the image comparison unit 606 compares the reference image with the reading variation amount corrected according to the paper type and the read image with the reading variation amount corrected according to the paper type, and detects the color variation amount.

[0058] In step S29, the color variation correction amount generation unit 607 generates a correction amount (color variation correction amount) of the attached toner amount. In step S30, the image formation control unit 604 performs color correction processing on the RIP image from the printer control unit 601 based on the color variation correction amount generated by the color variation correction amount generation unit, and then performs printing. Thereby, it is possible to prevent the inconvenience of excessively correcting even the variation amount on the image reading side where the images were not originally superimposed, and to correct only the variation amount superimposed on the image formation side and perform image printing.

[0059] (Effect of the Second Embodiment) As is clear from the above description, in the printing system of the second embodiment, since the reading variation amount on the read image differs for each image forming apparatus 103 and for each paper type, the reading variation amount and the paper type information are associated and stored in a storage unit such as the HDD 304. Then, when printing is performed with the same image forming apparatus 103 and the same paper type, the previously detected reading variation amount is reused. Thereby, when printing again on paper of the same paper type, not only can the troublesome operation of acquiring the reading variation amount again be omitted, but also the same effects as those of the first embodiment described above can be obtained.

[0060] [Third Embodiment] Next, a printing system according to the third embodiment will be described. The printing systems of the above-described embodiments were examples in which an electrophotographic image forming apparatus was provided, but the printing system of this third embodiment is an example in which an inkjet image forming apparatus is provided. Note that the only difference between the above-described embodiments and the third embodiment described below is this point. For this reason, only the differences between the two will be described below, and duplicate descriptions will be omitted.

[0061] FIG. 16 is a schematic cross-sectional view of an inkjet image forming apparatus provided in the printing system of this third embodiment. As shown in FIG. 16, the inkjet image forming apparatus includes a paper feeding unit 501, an image forming unit 506, a drying unit 502, and a paper discharging unit 503.

[0062] In the image forming apparatus 103, an image is formed on a sheet P, which is a recording material as a sheet material fed from the paper feeding unit 501, with ink, which is a liquid for image formation, by the image forming unit 506. Then, after the ink adhering to the sheet is dried in the drying unit 502, the sheet is discharged from the paper discharging unit 503.

[0063] (Paper Feeding Unit) The paper feeding unit 501 includes a paper feeding tray 511 on which a plurality of sheets P are stacked, a feeding device 512 that separates and feeds out the sheets P one by one from the paper feeding tray 511, and a registration roller pair 513 that feeds the sheet P into the image forming unit 506.

[0064] As the feeding device 512, any feeding device such as a device using rollers and cylinders or a device using air suction can be used. The sheet fed out from the paper feeding tray 511 by the feeding device 512 is fed into the image forming unit 506 when the leading edge thereof reaches the registration roller pair 513 and the registration roller pair 513 is driven at a predetermined timing. Note that the configuration of the paper feeding unit 501 is not limited as long as it can feed the sheet P into the image forming unit 506.

[0065] (Image Forming Unit) The image forming unit 506 includes a receiving cylinder 561 that receives the fed sheet P, a sheet carrying drum 562 that carries and conveys the sheet P conveyed by the receiving cylinder 561 on its outer peripheral surface, an ink ejection unit 564 that ejects ink toward the sheet P carried on the sheet carrying drum 562, and a delivery cylinder 565 that delivers the sheet P conveyed by the sheet carrying drum 562 to the drying unit 502.

[0066] The sheet P conveyed from the paper feeding unit 501 to the image forming unit 506 has its leading edge gripped by a sheet gripper provided on the surface of the receiving cylinder 561 and is conveyed along with the surface movement of the receiving cylinder 561. The sheet P conveyed by the receiving cylinder 561 is delivered to the sheet carrying drum 562 at the opposing position to the sheet carrying drum 562.

[0067] A sheet gripper is also provided on the surface of the sheet carrying drum 562, and the leading edge of the sheet is gripped by the sheet gripper. Further, a plurality of suction holes are dispersedly formed on the surface of the sheet carrying drum 562, and a suction airflow directed toward the inside of the sheet carrying drum 562 is generated in each suction hole by a suction device 563. The sheet P delivered from the receiving cylinder 561 to the sheet carrying drum 562 has its leading edge gripped by the sheet gripper and is adsorbed to the surface of the sheet carrying drum 562 by the suction airflow and is conveyed along with the surface movement of the sheet carrying drum 562.

[0068] The ink ejection unit 564 ejects four colors of ink, C (cyan), M (magenta), Y (yellow), and K (black), to form an image, and includes individual liquid ejection heads 564C, 564M, 564Y, and 564K for each ink. The liquid ejection heads 564C, 564M, 564Y, and 564K are not limited in their configuration as long as they eject liquid, and any configuration can be adopted. If necessary, a liquid ejection head for ejecting special inks such as white, gold, and silver may be provided, or a liquid ejection head for ejecting a liquid that does not constitute an image, such as a surface coating liquid, may be provided.

[0069] The liquid ejection heads 564C, 564M, 564Y, and 564K of the ink ejection unit 364 are each controlled in their ejection operations by drive signals corresponding to the image information. When the sheet P carried on the sheet carrying drum 562 passes through the area facing the ink ejection unit 564, inks of respective colors are ejected from the liquid ejection heads 564C, 564M, 564Y, and 564K, and an image corresponding to the image information is formed. Note that the image forming unit 506 is not limited in its configuration as long as it forms an image by attaching liquid onto the sheet P.

[0070] (Drying unit) The drying unit 502 includes a drying mechanism 521 for drying the ink adhered onto the sheet P in the image forming unit 506, and a conveyance mechanism 522 for conveying the sheet P conveyed from the image forming unit 506. The sheet P conveyed from the image forming unit 506 is received by the conveyance mechanism 522 and then conveyed so as to pass through the drying mechanism 521, and is delivered to the paper discharge unit 503. When passing through the drying mechanism 521, the ink on the sheet P is subjected to a drying process, whereby liquid components such as moisture in the ink evaporate, the ink adheres to the sheet P, and curling of the sheet P is suppressed.

[0071] (Paper discharge unit) The paper discharge unit 503 includes a paper discharge tray 531 on which a plurality of sheets P are stacked. The sheets P conveyed from the drying unit 502 are sequentially stacked and held on the paper discharge tray 531. Note that the paper discharge unit 503 is not limited in its configuration as long as it discharges the sheet P.

[0072] (Other functional units) The image forming apparatus 103 includes a paper feeding unit 501, an image forming unit 506, a drying unit 502, and a paper discharge unit 503, but other functional units may be appropriately added. For example, a preprocessing unit for performing preprocessing of image formation may be added between the paper feeding unit 501 and the image forming unit 506. Also, a postprocessing unit for performing postprocessing of image formation may be added between the drying unit 502 and the paper discharge unit 503.

[0073] Examples of the preprocessing unit include those that perform a treatment liquid application process of applying a treatment liquid that reacts with the ink to suppress bleeding to the paper P, but the content of the preprocessing is not particularly limited. Examples of the postprocessing unit include a paper reverse conveyance process for reversing the paper on which an image is formed by the image forming unit 506 and conveying it back to the image forming unit 506 to form an image on both sides of the paper P, a process of binding a plurality of sheets of paper P on which images are formed, a correction mechanism for correcting paper deformation, or a cooling mechanism for cooling the paper. However, the content of the postprocessing is not particularly limited either.

[0074] (Effect of the Third Embodiment) Even when such an inkjet type image forming apparatus is provided, the same effects as those of the above-described embodiments can be obtained.

[0075] Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention.

[0076] For example, the "paper" is not limited to paper in terms of material, and includes OHP films (polyester films), cloth, glass, substrates, etc., and any material on which ink droplets and other liquids can adhere. Also, the "paper" includes those referred to as recording media, recording papers, recording sheets, etc. Further, image formation, recording, printing, imprinting, and printing are all synonymous.

[0077] Also, the "inkjet printer device" may form an image by discharging a liquid onto media such as paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, and ceramics. Further, "image formation" includes not only forming an image such as characters or graphics on a medium, but also forming an image having no meaning such as a pattern on a medium (simply landing a liquid (droplet) on the medium).

[0078] In addition, unless otherwise particularly limited, the term "ink" is not limited to what is specifically called ink, but is used as a general term for all liquids capable of forming an image, including recording liquids, fixing treatment liquids, liquids, etc. For example, "ink" includes DNA (Deoxyribonucleic Acid) samples, resists, pattern materials, resins, etc., as well as aqueous latex inks for signgraphics, etc.

[0079] In addition, the "image" is not limited to planar ones, but also includes three-dimensionally formed images or three-dimensional shaped objects.

[0080] In addition, the present invention can be applied to single-function machines such as printer devices, facsimile machines, copiers, etc., or multifunction machines thereof.

[0081] In addition, as a device for discharging a liquid, not only a device capable of discharging a liquid onto an object to which the liquid can adhere, but also a device for discharging the liquid into the air or into a liquid may be used.

[0082] This "device for discharging a liquid" may include means related to the feeding, conveying, and paper discharging of objects to which the liquid can adhere, as well as other pretreatment devices, post-treatment devices, etc.

[0083] In addition, the "device for discharging a liquid" is not limited to those in which a significant image such as characters or figures is visualized by the discharged liquid. For example, those forming patterns that have no meaning by themselves are also included.

[0084] In addition, the "object to which the liquid can adhere" means an object to which the liquid can adhere at least temporarily, such as an object that adheres and adheres firmly, or an object that adheres and penetrates. Specific examples include recording media such as paper, recording paper, recording sheets, films, cloth, electronic components such as electronic substrates and piezoelectric elements, powder layers (powder layers), organ models, media such as inspection cells, and unless otherwise particularly limited, all objects to which the liquid adheres are included.

[0085] The material of "something to which liquid can adhere" may be paper, thread, fiber, fabric, leather, metal, plastic, glass, wood, ceramics, etc., as long as liquid can adhere to it even temporarily.

[0086] Also, the "liquid" may be any material having a viscosity and surface tension that can be ejected from the head, and is not particularly limited. However, it is preferably a material whose viscosity becomes 30 mPa·s or less at normal temperature and pressure, or by heating or cooling. More specifically, it includes solvents such as water and organic solvents, colorants such as dyes and pigments, polymerizable compounds, resins, functional imparting materials such as surfactants, biocompatible materials such as DNA, amino acids, proteins, and calcium, edible materials such as natural pigments, etc., and solutions, suspensions, emulsions, etc. containing these. These can be used, for example, in applications such as inkjet inks, surface treatment liquids, components of electronic elements and light-emitting elements, and liquids for forming electronic circuit resist patterns.

[0087] Also, the "device for ejecting liquid" includes, but is not limited to, a device in which a liquid ejection head and something to which liquid can adhere move relative to each other. Specific examples include serial type devices that move the liquid ejection head and line type devices that do not move the liquid ejection head.

[0088] Also, as the "device for ejecting liquid", there are also a treatment liquid coating device that ejects a treatment liquid onto paper for the purpose of modifying the surface of the paper, and an injection granulation device that injects a composition liquid in which raw materials are dispersed in a solution through a nozzle to granulate fine particles of the raw materials.

[0089] Also, the "liquid ejection head 564" is not limited by the pressure generating means used. For example, in addition to piezoelectric actuators (which may use laminated piezoelectric elements), thermal actuators using electrothermal conversion elements such as heating resistors, and electrostatic actuators composed of a diaphragm and a counter electrode may also be used.

[0090] Also, in the terms of this application, image formation, recording, printing, imprinting, printing, shaping, etc. are all the same shall be the synonymous term.

[0091] Also, the "liquid ejection head 564" is housed in the "liquid ejection unit". This liquid ejection unit is an integrated unit of functional components and mechanisms with the liquid ejection head, and is an assembly of components related to liquid ejection. For example, the "liquid ejection unit" includes at least one of the configurations of a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, and a main scanning movement mechanism combined with the liquid ejection head.

[0092] Here, the integration means, for example, that the liquid ejection head and the functional components and mechanisms are fixed to each other by fastening, adhesion, engagement, etc., or one is movably held with respect to the other. Also, the liquid ejection head and the functional components and mechanisms may be configured to be detachable from each other.

[0093] For example, as a liquid ejection unit, there is one in which the liquid ejection head and the head tank are integrated. Also, there is one in which the liquid ejection head and the head tank are integrated by being connected to each other with a tube or the like. Here, a unit including a filter can also be added between the head tank and the liquid ejection head of these liquid ejection units.

[0094] Also, as a liquid ejection unit, there is one in which the liquid ejection head and the carriage are integrated.

[0095] Also, as a liquid ejection unit, there is one in which the liquid ejection head is movably held on a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated. Also, there is one in which the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated.

[0096] Also, as a liquid ejection unit, there is one in which a cap member that is a part of the maintenance and recovery mechanism is fixed to the carriage to which the liquid ejection head is attached, and the liquid ejection head, the carriage, and the maintenance and recovery mechanism are integrated.

[0097] In addition, as a liquid ejection unit, there is one in which a tube is connected to a liquid ejection head to which a head tank or a flow path component is attached, and the liquid ejection head and the supply mechanism are integrated. Through this tube, the liquid in the liquid storage source is supplied to the liquid ejection head.

[0098] The main scanning movement mechanism shall include the guide member alone. Also, the supply mechanism shall include the tube alone and the loading unit alone.

[0099] Such embodiments and modifications of the embodiments are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0100] 101 Client personal computer device 102 Digital front end (DFE) 103 Image forming apparatus 104 Management server 301 CPU of the image forming apparatus 304 HDD or SSD 306 Image forming unit 307 Reading unit 350 Reading characteristic table 406 In-line sensor 601 Printer control unit 602 Reference image generation unit 603 Reading variation amount generation unit 603a Reading variation amount generation unit 603b Reading variation amount generation unit 604 Image forming control unit 605 Printed image reading unit 606 Image comparison unit 607 Color variation correction amount generation unit 650 Reading characteristic generation unit 651 Reading characteristic storage control unit

Prior Art Documents

Patent Documents

[0101] [Patent Document 1] Japanese Patent Application Laid-Open No. 11-355636

Claims

1. An image formation control unit that controls an image formation unit to form an image based on drawing data, A reading control unit that controls a reading unit to read the image formed by the image formation control unit, A reading variation amount generation unit that generates a reading variation amount of the reference image corresponding to the ratio between the reading value of the maximum reference image, which is the image with the maximum pixel value among the images of the drawing data, and the reading value of the reference image, which is the image of the drawing data, An addition image generation unit that generates an addition image obtained by adding the reading variation amount of the reference image to the reference image, A color variation correction amount generation unit that generates a color variation correction amount used for color variation correction during image formation by subtracting the addition image from the reading image formed by the image formation unit and read by the reading unit, and supplies the color variation correction amount to the image formation control unit, An image processing apparatus having the above components.

2. The reading variation amount generation unit calculates, as the reading variation amount of the reference image, a value obtained by multiplying the ratio between the reading value of the maximum reference image, which is the image with the maximum pixel value among the images of the drawing data, and the reading value of the reference image, which is the image of the drawing data, by the reading variation amount superimposed on the maximum reference image. The image processing apparatus according to claim 1, characterized in that.

3. The reading variation amount generation unit uses, as the reading value of the maximum reference image, the reading value of the blank part of the paper, which is the non-printed part on the paper on which printing based on the drawing data is performed. The image processing apparatus according to claim 1 or claim 2, characterized in that.

4. A reference image generation unit that generates a reference image based on drawing data, A printed image reading unit that generates a reading image by reading, by the image formation control unit, the printed image of the drawing data printed on a storage medium, A reading variation amount correction unit that acquires, from a storage unit in which reading variation amount information generated based on the reading image of the chart image printed on the storage medium is stored for each type of the storage medium, the reading variation amount information corresponding to the type of the storage medium on which the drawing data is printed, and generates a corrected reference image obtained by correcting the reading variation amount of the reference image from the reference image generation unit, A color variation correction amount generation unit that compares the corrected reference image and the reading image, generates a color variation correction amount used for color variation correction during image formation, and supplies the color variation correction amount to the image formation control unit, An image processing apparatus having the above components.

5. A computer, An image formation control unit that controls an image formation unit to form an image based on drawing data, A reading control unit that controls a reading unit to read the image formed by the image formation control unit; A reading variation amount generation unit that generates an addition image obtained by adding the reading variation amount of the reference image corresponding to the ratio between the reading value of the maximum reference image, which is the image with the maximum pixel value among the images of the drawing data, and the reading value of the reference image, which is the image of the drawing data, to the reference image; Functioning as a color variation correction amount generation unit that generates a color variation correction amount used for color variation correction during image formation by subtracting the addition image from the reading image formed by the image formation unit and read by the reading unit, and supplies the color variation correction amount to the image formation control unit An image processing program characterized by the above.

6. A computer, A reference image generation unit that generates a reference image based on drawing data; A print image reading unit that generates a reading image obtained by reading the print image of the drawing data printed on a storage medium by an image formation control unit; Based on the reading variation amount information generated from the reading image of the chart image printed on the storage medium, the reading variation amount information corresponding to the type of the storage medium on which the drawing data is printed is acquired from a storage unit that stores the reading variation amount information for each type of the storage medium, and a corrected reference image obtained by correcting the reading variation amount of the reference image from the reference image generation unit is generated. A reading variation amount correction unit; Functioning as a color variation correction amount generation unit that compares the corrected reference image and the reading image, generates a color variation correction amount used for color variation correction during image formation, and supplies the color variation correction amount to the image formation control unit An image processing program characterized by the above.

7. An image formation unit that forms an image; An image formation control unit that controls the image formation unit to form an image corresponding to drawing data; A reading control unit that controls a reading unit to read the image formed by the image formation control unit; A reading variation amount generation unit that generates an addition image obtained by adding the reading variation amount of the reference image corresponding to the ratio between the reading value of the maximum reference image, which is the image with the maximum pixel value among the images of the drawing data, and the reading value of the reference image, which is the image of the drawing data, to the reference image; A color variation correction amount generation unit that generates a color variation correction amount used for color variation correction during image formation by subtracting the addition image from the reading image formed by the image formation unit and read by the reading unit, and supplies the color variation correction amount to the image formation control unit; An image forming apparatus having the above.

8. An image formation unit that forms an image; A reference image generation unit that controls the image forming unit to generate a reference image based on drawing data; A print image reading unit that generates a read image by reading a print image of the drawing data printed on a storage medium by an image forming control unit that controls the image forming unit; A reading variation amount correction unit that acquires reading variation amount information corresponding to the type of the storage medium on which the drawing data is printed from a storage unit that stores the reading variation amount information generated based on the read image of the chart image printed on the storage medium for each type of the storage medium, and generates a corrected reference image obtained by correcting the reading variation amount of the reference image from the reference image generation unit; A color variation correction amount generation unit that compares the corrected reference image and the read image, generates a color variation correction amount used for color variation correction at the time of image formation, and supplies the color variation correction amount to the image forming control unit; An image forming apparatus having the above components.

Images