Image forming apparatus, image forming system, and image forming method

Abstract

To provide an image forming apparatus, an image forming system, and an image forming method with which highly accurate density correction and tone correction can be simultaneously achieved by using information acquired by an in-line sensor mounted inside an image forming unit.SOLUTION: An image forming apparatus comprises: a read image processing unit that, when performing tone correction processing, converts information on a pattern for tone correction read by an in-line sensor into density values; a maximum density control unit that, on the basis of, the maximum density value of the density values and a target maximum density value, calculates a correction amount for the maximum density value, and according to the correction amount, changes maximum density settings included in paper settings for which correction is executed; and a paper maximum density setting control unit that, after the change of the maximum density settings, updates the maximum density settings included in the paper settings. After the update of the maximum density settings, an image correction processing control unit executes both density correction and tone correction for an image forming unit again by using the pattern for tone correction.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an image forming apparatus, an image forming system, and an image forming method.

Background Art

[0002] In digital equipment used in the commercial printing business, movements toward automation of each function are becoming active. Also regarding color matching (color correction technology), which is important in digital equipment, automation that does not trouble the user is progressing. In order to achieve automation of color matching in digital equipment, it is necessary to perform density stabilization and color correction using sensor information installed in the digital equipment.

[0003] Patent Document 1 discloses a technique for adjusting the contrast voltage of a printer until a target maximum density value is reached for the purpose of adjusting the maximum density value of an image forming apparatus such as a printer to the target maximum density value, and then performing tone correction equivalent to calibration.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in high-precision color correction technology, chart printing for adjusting the maximum density value every time is essential, and the target value of the maximum density value, the setting of the maximum density value, calibration data, and paper information are not linked, and unevenness between pages of the maximum density value chart is not considered.

[0005] In the technology of Patent Document 1, in order to perform highly accurate calibration color correction, chart printing for adjusting the maximum density value is essential, and printing of a chart for maximum density adjustment different from the calibration correction chart is required multiple times. Further, in the technology of Patent Document 1, the target value of the maximum density value, the set value of the maximum density value, the calibration data, and the paper information are not associated with each other, and every time, printing of a chart for maximum density adjustment is required. Furthermore, when acquiring the maximum density value, density unevenness within a page is considered, but unevenness of the maximum density value between pages is not considered.

[0006] The present invention has been made in view of the above, and an object thereof is to provide an image forming apparatus, an image forming system, and an image forming method capable of simultaneously realizing highly accurate density correction and gradation correction by using information acquired by an in-line sensor mounted inside an image forming unit.

Means for Solving the Problems

[0007] In order to solve the above-described problems and achieve the object, the present invention includes an image forming unit, an in-line sensor mounted inside the image forming unit, an image forming control unit that controls the image forming unit to form a gradation correction pattern, an image correction processing control unit that performs both density correction and gradation correction of the image forming unit using the gradation correction pattern, a reading control unit that controls the in-line sensor to read the gradation correction pattern, a reading image processing unit that converts reading information of the gradation correction pattern by the in-line sensor into a density value when performing gradation correction processing, a maximum density control unit that calculates a correction amount of the maximum density value based on the maximum density value and the target maximum density value among the density values, and changes the maximum density setting including paper setting to perform correction according to the correction amount, and a paper maximum density setting control unit that updates the maximum density setting included in the paper setting after changing the maximum density setting. The image correction processing control unit performs both density correction and gradation correction of the image forming unit again using the gradation correction pattern after the update of the maximum density setting.

Effects of the Invention

[0008] According to the present invention, it is possible to simultaneously achieve high-precision density correction and gradation correction by using information acquired by an in-line sensor mounted inside an image forming unit, and thus the effect is achieved.

Brief Description of the Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] With reference to the accompanying drawings, embodiments of an image forming apparatus, an image forming system, and an image forming method will be described in detail below.

[0011] FIG. 1 is a diagram showing an example of the configuration of an image forming system according to the present embodiment. As shown in FIG. 1, the image forming system 1 according to the present embodiment includes a client PC (Personal Computer) 101, a DFE (Digital Front End) 102, an image forming apparatus 103, and a management server 104.

[0012] The client PC 101 creates a print job that a user wants to print and transmits the print job to the DFE 102 or the management server 104. The client PC 101 includes a display unit such as a liquid crystal display and an input device including a mouse and a keyboard.

[0013] The DFE 102 receives a print job from the client PC 101 or the management server 104, and creates rendering data by a RIP engine based on the received print job. Then, the DFE 102 transmits the rendering data to the image forming apparatus 103.

[0014] The image forming apparatus 103 forms an image based on the rendering data received from the DFE 102. Further, when a reading instruction is given, the image forming apparatus 103 reads an image using an in-line sensor mounted inside the image forming apparatus 103.

[0015] The management server 104 manages the print job received from the client PC 101. Further, the management server 104 transmits the print job to the DFE 102 in response to a request from the DFE 102.

[0016] FIG. 2 is a block diagram showing an example of the hardware configuration of the DFE according to the present embodiment. As shown in FIG. 2, the DFE 102 according to the present embodiment includes a CPU (Central Processing Unit) 201, a ROM (Read Only Memory) 202, a RAM (Random Access Memory) 203, an HDD (Hard Disk Drive) / SSD (Solid State Drive) 204, and an I / F 205.

[0017] The CPU 201 uses the RAM 203 as a work area and executes the programs stored in the ROM 202. The HDD / SSD 204 is used as a storage unit and stores preset setting values. The information stored in the HDD / SSD 204 may be used by the CPU 201 when reading and executing programs. The I / F 205 is an interface that enables communication between the DFE 102 and the client PC 101, the image forming apparatus 103, and the management server 104.

[0018] FIG. 3 is a diagram showing an example of the hardware configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 3, the image forming apparatus 103 according to the present embodiment includes a CPU 301, a ROM 302, a RAM 303, an HDD / SSD 304, an I / F 305, an image forming unit 306, and a reading unit 307.

[0019] The CPU 301 uses the RAM 303 as a work area and controls the operation of the entire image forming apparatus 103 by executing the programs stored in the ROM 302. The HDD / SSD 304 is used as a storage unit and stores preset setting values. The information stored in the HDD / SSD 304 may be used by the CPU 301 when reading and executing programs.

[0020] I / F 305 is an interface that enables communication between the image forming apparatus 103, the DFE 102, the client PC 101, and the management server 104. The image forming unit 306 is a printing engine that forms a printed image on a printing paper (an example of a recording medium). The reading unit 307 is a reading device (an example of an in-line sensor) that reads the printed image formed on the printing paper and is mounted inside the image forming unit 206. The paper feeding unit 500 is an example of a supply unit that can supply printing paper to the image forming unit 306.

[0021] FIG. 4 is a diagram showing an example of the functional configuration of the DFE and the image forming apparatus according to the present embodiment. As shown in FIG. 4, the DFE 102 according to the present embodiment includes an image processing unit 401, a maximum density control unit 402, an image correction processing control unit 403, a paper maximum density setting control unit 404, and a read image processing unit 408.

[0022] The image processing unit 401 performs a start notification when starting the image processing function and image processing during the execution of a print job.

[0023] The maximum density control unit 402 is a control unit that calculates information regarding the maximum density value and performs a determination of the change determination of the calculated maximum density value when the image forming system 1 is executed. Specifically, the maximum density control unit 402 calculates a correction amount of the maximum density value based on the maximum density value and the target maximum density value among the density values converted from the patch information by the read image processing unit 408 described later. Next, the maximum density control unit 402 changes the maximum density setting included in the paper setting for performing the correction according to the calculated correction amount.

[0024] Then, when a change occurs in the maximum density setting, the maximum density control unit 402 notifies the paper maximum density setting control unit 404 of the maximum density setting. As a result, calculation of data necessary for correction of the maximum density value is performed using the color information (patch information) obtained by reading the tone correction pattern, and density correction and tone correction can be performed using the tone correction pattern. As a result, it is possible to simultaneously realize high-precision density correction and tone correction using the patch information acquired by the reading unit 307 mounted inside the image forming unit 306.

[0025] The image correction processing control unit 403 is a control unit that calculates a correction curve such as a tone correction curve for performing color correction such as tone correction based on a target value and a colorimetric value (data of the read image processing unit 408) for performing color correction processing, and applies the calculated correction curve to a print job. Specifically, the image correction processing control unit 403 executes both density correction and tone correction of the image forming unit 306 using a tone correction pattern. Further, after the update of the maximum density setting included in the paper setting by the paper maximum density setting control unit 404 described later, the image correction processing control unit 403 executes both density correction and tone correction of the image forming unit 306 again using the tone correction pattern.

[0026] Further, the image correction processing control unit 403 includes a storage unit that stores, in addition to process colors, tone correction target values and tone correction data (tone correction curves) for each recording medium such as paper for special colors. Also, in the present embodiment, the image correction processing control unit 403 includes a special color toner determination control unit that uses the tone correction data corresponding to the special color for tone correction when the color used in the image forming unit 306 is switched to a special color.

[0027] The paper maximum density setting control unit 404 stores paper settings and is a control unit that changes and saves paper settings. Further, when the maximum density setting is changed, the paper maximum density setting control unit 404 saves the changed maximum density setting in the paper settings. That is, after the maximum density setting is changed, the paper maximum density setting control unit 404 updates the maximum density setting included in the paper settings. Also, the paper maximum density setting control unit 404 manages (for example, stores) by associating the maximum density target value, the maximum density setting, the tone correction data, and the recording medium such as paper.

[0028] The read image processing unit 408 converts the patch information read by the read control unit 406 described later into density values and performs data processing that can be used for determination and color correction processing. Specifically, when performing tone correction processing, the read image processing unit 408 converts the patch information (an example of read information) of the tone correction pattern by the reading unit 307 into density values.

[0029] As shown in FIG. 4, the image forming apparatus 103 according to the present embodiment includes an image forming control unit 405, a reading control unit 406, and a read image acquisition unit 407.

[0030] The image forming control unit 405 is a control unit that forms an image of a print job and a chart. Specifically, the image forming control unit 405 performs image formation using the maximum density setting included in the paper setting.

[0031] During the automatic calibration, the reading control unit 406 controls the reading unit 307 during the conveyance of the print paper to read an image-formed chart for automatic calibration (an example of a tone correction pattern).

[0032] The read image acquisition unit 407 acquires patch information during the conveyance of the print paper. Here, the patch information is information on patches included in the chart for automatic calibration read by the reading unit 307. Also, the patch information is used for color correction processing. Therefore, the read image acquisition unit 407 collectively stores the patch information and transfers the patch information to the read image processing unit 408.

[0033] In the present embodiment, although the DFE 102 and the image forming apparatus 103 cooperate to function as an example of an image forming apparatus, the present invention is not limited thereto, and it is also possible that only the image forming apparatus 103 functions as an example of an image forming apparatus.

[0034] FIG. 5 is a flowchart showing an example of the flow of the maximum density value adjustment process and the automatic calibration executed in the image forming system according to the present embodiment.

[0035] When an automatic calibration is instructed to perform the color correction process of the image forming apparatus 103, the image forming control unit 405 of the image forming apparatus 103 controls the image forming unit 306 to print (form an image) an automatic calibration pattern including a chart for automatic calibration on the printing paper (step S501).

[0036] During the execution of the automatic calibration, the reading control unit 406 of the image forming apparatus 103 controls the reading unit 307 installed inside the image forming apparatus 103 to read the image output pattern (chart for automatic calibration) during printing (step S502). Next, the read image acquisition unit 407 of the image forming apparatus 103 acquires the patch information of the read image output pattern during the conveyance of the printing paper. Further, the read image acquisition unit 407 converts the acquired patch information (sensor information) into density values (step S503).

[0037] Next, the maximum density control unit 402 of the DFE 102 determines whether to adjust the maximum density value based on the difference information between the converted density value and the target maximum density value (step S504). If the maximum density value among the converted density values reaches the target maximum density value, the maximum density control unit 402 determines that the adjustment of the target maximum density value is unnecessary (step S504: No).

[0038] In this case, the image correction processing control unit 403 of the DFE 102 generates a tone correction curve, which is a correction curve for performing tone correction, based on the patch information obtained by reading the image output pattern (step S505). Further, the image correction processing control unit 403 applies the generated tone correction curve to the print job (step S506). Thereafter, the image forming control unit 405 of the image forming apparatus 103 performs image output (printing) of the print image on the printing paper according to the print job (step S507).

[0039] On the other hand, when the maximum density value among the converted density values has not reached the target maximum density value, the maximum density control unit 402 of the DFE 102 determines that adjustment of the target maximum density value is necessary (step S504: Yes). In this case, the maximum density control unit 402 calculates a correction amount for the maximum density value to achieve the target maximum density value based on the maximum density value and the target maximum density value (step S508). Further, the maximum density control unit 402 changes the maximum density value according to the calculated correction amount (step S509). Thereafter, the maximum density setting control unit 404 of the DFE 102 stores the maximum density setting corresponding to the changed maximum density value in the paper setting (step S510).

[0040] FIG. 6 is a diagram showing an example of a chart for automatic calibration printed during the execution of automatic calibration of the image forming apparatus according to the present embodiment. In the present embodiment, as shown in FIG. 6, the chart for automatic calibration is a chart in which patches (for example, patches C1, M1) of the engine solid density (maximum density value) of each color toner are sparsely arranged in the plane of the printing paper and printed on a plurality of pages. Thereby, it is possible to obtain a chart capable of correcting unevenness in density values within the plane of the printing paper and unevenness in density values between pages.

[0041] Further, by including a patch of the maximum density value in the chart for automatic calibration, it is not necessary to print a chart for adjusting the maximum density value separately from the chart for automatic calibration, and the maximum density value can be obtained using the chart for automatic calibration. In addition, it is possible to perform accurate correction regarding the maximum density value in consideration of unevenness in density values within the plane of the printing paper and unevenness in density values between pages in the image forming apparatus 103.

[0042] FIG. 7 is a diagram for explaining an example of a display screen including the implementation result of automatic calibration and the acquisition result of the maximum density value in the image forming system according to the present embodiment. In the present embodiment, the chart for automatic calibration includes a plurality of patches for gradation correction in addition to the patch of the maximum density value. Therefore, the reading image acquisition unit 407 of the image forming apparatus 103 acquires the patch information of the patch for gradation correction in addition to the patch information of the patch of the maximum density value. Therefore, according to the image forming system according to the present embodiment, a graph showing the relationship between the density value (measured value) converted from the patch information and the relative value (%) of the target density value can be obtained.

[0043] Therefore, in the present embodiment, the client PC 101 displays a display screen including the target maximum density value, the density value (measured value), the notch setting (maximum density setting), and the determination item as to whether the maximum density value satisfies the target maximum density value, in addition to the graph (result of automatic calibration) showing the relationship between the measured value and the relative value.

[0044] Further, when there is a color plate (for example, black K) for which the maximum density value does not satisfy the target maximum density value, the client PC 101 may include a message indicating that the target maximum density value is not satisfied in the display screen. Furthermore, the client PC 101 may include a re-execution button for instructing re-execution of automatic calibration in the display screen. When the re-execution button included in the display screen on the client PC 101 is pressed, the image forming apparatus 103 executes printing of the chart for automatic calibration with the maximum density setting updated. The user can instruct re-execution of adjustment of the maximum density value by pressing the re-execution button.

[0045] FIG. 8 is a diagram for explaining another example of a display screen including the implementation result of automatic calibration and the acquisition result of the maximum density value in the image forming system according to the present embodiment. If there is a color plate (for example, black K) whose maximum density value does not satisfy the target maximum density value and automatic calibration is re-executed, and when the maximum density values of all color plates satisfy the target maximum density value, the client PC 101 displays a display screen including a determination item indicating that the maximum density values of all color plates satisfy the target maximum density value. In this case, since it is not necessary to re-execute the automatic calibration, the client PC 101 displays it on the display screen in a state where the re-execution button cannot be pressed.

[0046] FIG. 9 is a diagram for explaining an example of the relationship among the maximum density setting, the target maximum density value, and the read information (maximum density value) in the image forming system according to the present embodiment. The paper setting includes a maximum density setting for adjusting the maximum density value when printing a printed image by the image forming apparatus 103. When the maximum density value of the printed image printed according to the paper setting used for printing does not reach the target maximum density value, the maximum density control unit 402 of the DFE 102 can increase or decrease the maximum density value when the printed image is output by the image forming apparatus 103 by changing the maximum density setting included in the paper setting.

[0047] Specifically, the maximum density control unit 402 of the DFE 102 calculates the difference information between the target maximum density value and the maximum density value in the color plate that needs to satisfy the target maximum density value based on the target maximum density value and the maximum density value, and updates the maximum density setting included in the paper setting based on the difference information. By updating the maximum density setting included in the paper setting, it becomes possible to perform automatic calibration in a state where the target maximum density value is satisfied when correcting the maximum density value in the future. Also, even if the maximum density value changes due to changes over time, it becomes possible to notice that the maximum density value has changed during the execution of automatic calibration, and automatic calibration can be performed with the optimal maximum density value.

[0048] Thus, according to the image forming system 1 according to this embodiment, data necessary for correcting the maximum density value is calculated using the color information (patch information) obtained by reading the gradation correction pattern, and density correction and gradation correction can be performed using the gradation correction pattern. As a result, it is possible to simultaneously achieve highly accurate density correction and gradation correction using the patch information obtained by the reading unit 307 mounted inside the image forming unit 306.

[0049] In the above embodiment, an example in which the image forming apparatus of the present invention is applied to a multifunction device having at least two functions among a copying function, a printer function, a scanner function, and a facsimile function has been described. However, the present invention can be applied to any image forming apparatus such as a copying machine, a printer, a scanner device, a facsimile device, and the like.

Explanation of Reference Numerals

[0050] 101 Client PC 102 DFE 103 Image forming apparatus 104 Management server 401 Image processing unit 402 Maximum density control unit 403 Image correction processing control unit 404 Paper maximum density setting control unit 405 Image forming control unit 406 Reading control unit 407 Read image acquisition unit 408 Read image processing unit

Prior Art Documents

Patent Documents

[0051]

Patent Document 1

Claims

1. An image forming unit, An in-line sensor mounted inside the image forming unit, An image forming control unit that controls the image forming unit to form a tone correction pattern, An image correction processing control unit that performs both density correction and tone correction of the image forming unit using the tone correction pattern, A reading control unit that controls the in-line sensor to read the tone correction pattern, A reading image processing unit that converts the reading information of the tone correction pattern by the in-line sensor into density values when performing tone correction processing, A maximum density control unit that calculates a correction amount for the maximum density value based on the maximum density value and the target maximum density value among the density values, and changes the maximum density setting included in the paper setting to perform correction according to the correction amount, A paper maximum density setting control unit that updates the maximum density setting included in the paper setting after changing the maximum density setting, and an image forming apparatus comprising: After the update of the maximum density setting, the image correction processing control unit uses the tone correction pattern again to perform both density correction and tone correction of the image forming unit.

2. The tone correction pattern according to claim 1, wherein patches of the maximum density value are sparsely arranged in the plane of the recording medium and printed on a plurality of recording media.

3. The paper maximum density setting control unit further manages by associating a target value of the maximum density of the image forming unit, the maximum density setting, tone correction data, and a recording medium. The image forming apparatus according to claim 1 or 2.

4. The image correction processing control unit, A storage unit that stores tone correction target values and tone correction data for each recording medium in addition to process colors and stores them separately for special colors, A special color toner determination control unit that uses the tone correction data corresponding to the special color for tone correction when the color used in the image forming unit is switched to the special color, The image forming apparatus according to any one of claims 1 to 3, comprising:

5. An image forming unit, An in-line sensor mounted inside the image forming unit, An image forming control unit that controls the image forming unit to form a tone correction pattern, An image correction processing control unit that performs both density correction and tone correction of the image forming unit using the tone correction pattern, A reading control unit that controls the in-line sensor to read the tone correction pattern, When performing gradation correction processing, a reading image processing unit that converts the reading information of the gradation correction pattern by the in-line sensor into density values; A maximum density control unit that calculates a correction amount for the maximum density value based on the maximum density value and the target maximum density value among the density values, and changes the maximum density setting included in the paper setting for performing correction according to the correction amount; A paper maximum density setting control unit that updates the maximum density setting included in the paper setting after changing the maximum density setting; and is provided with, The image correction processing control unit executes both density correction and gradation correction of the image forming unit again using the gradation correction pattern after updating the maximum density setting. An image forming system.

6. An image forming method executed by an image forming apparatus including an image forming unit and an in-line sensor mounted inside the image forming unit, A step in which an image formation control unit controls the image forming unit to form a gradation correction pattern; A step in which an image correction processing control unit executes both density correction and gradation correction of the image forming unit using the gradation correction pattern; A step in which a reading control unit controls an in-line sensor mounted inside the image forming unit to read the gradation correction pattern; A step in which a reading image processing unit converts the reading information of the gradation correction pattern by the in-line sensor into density values when performing gradation correction processing; A step in which a maximum density control unit calculates a correction amount for the maximum density value based on the maximum density value and the target maximum density value among the density values, and changes the maximum density setting included in the paper setting for performing correction according to the correction amount; A step in which a paper maximum density setting control unit updates the maximum density setting included in the paper setting after changing the maximum density setting; A step in which the image correction processing control unit executes both density correction and gradation correction of the image forming unit again using the gradation correction pattern after updating the maximum density setting; An image forming method including.

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