JP7697345B2 - Image forming apparatus, image forming system, and image forming method - Google Patents

Description

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

There is an increasing trend towards automating the various functions of digital devices used in commercial printing. Color matching (color correction technology), which is important for digital devices, is also becoming more automated, eliminating the need for users to do anything. To achieve the automation of color matching on digital devices, it is necessary to use sensor information installed on the digital device to stabilize density and perform color correction.

Patent document 1 discloses a technique for adjusting the maximum density value of an image forming device such as a printer to a target maximum density value by adjusting the contrast voltage of the printer until the target maximum density value is reached, and then performing tone correction equivalent to calibration.

However, high-precision color correction technology requires printing a chart to adjust the maximum density value each time, and the target maximum density value, maximum density value setting, calibration data, and paper information are not linked, so unevenness between pages of the maximum density value chart is not taken into account.

In the technology of Patent Document 1, in order to perform highly accurate calibration color correction, it is necessary to print a chart for adjusting the maximum density value, and a chart for adjusting the maximum density, which is different from the calibration correction chart, must be printed multiple times. In addition, in the technology of Patent Document 1, the target value of the maximum density value, the setting value of the maximum density value, the calibration data, and the paper information are not linked, and it is necessary to print a chart for adjusting the maximum density every time. Furthermore, when obtaining the maximum density value, although the unevenness of density within a page is taken into account, the unevenness of the maximum density value between pages is not taken into account.

The present invention has been made in consideration of the above, and aims to provide an image forming apparatus, an image forming system, and an image forming method that can simultaneously achieve highly accurate density correction and gradation correction using information acquired by an in-line sensor mounted inside the image forming unit.

In order to solve the above-mentioned 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 an image of a gradation correction pattern, an image correction processing control unit that uses the gradation correction pattern to perform both density correction and gradation correction of the image forming unit, a reading control unit that controls the in-line sensor to read the gradation correction pattern, a read image processing unit that converts the read 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 for the maximum density value based on a maximum density value and a target maximum density value among the density values, and changes a maximum density setting included in a paper setting for performing 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, and the image correction processing control unit again uses the gradation correction pattern after updating the maximum density setting to perform both density correction and gradation correction of the image forming unit.

The present invention has the advantage that highly accurate density correction and gradation correction can be achieved simultaneously using information acquired by an in-line sensor installed inside the image forming unit.

FIG. 1 is a diagram showing an example of a configuration of an image forming system according to the present embodiment. FIG. 2 is a block diagram showing an example of a hardware configuration of the DFE according to the present embodiment. FIG. 3 is a diagram illustrating an example of a hardware configuration of the image forming apparatus according to the present embodiment. FIG. 4 is a diagram illustrating an example of a functional configuration of the DFE and the image forming apparatus according to the present embodiment. FIG. 5 is a flowchart showing an example of the flow of the maximum density value adjustment process and automatic calibration executed in the image forming system according to the present embodiment. FIG. 6 is a diagram showing an example of an automatic calibration chart printed when the automatic calibration is performed in the image forming apparatus according to the present embodiment. FIG. 7 is a diagram for explaining an example of a display screen including the results of automatic calibration and the results of maximum density value acquisition in the image forming system according to the present embodiment. FIG. 8 is a diagram for explaining another example of the display screen including the results of the automatic calibration and the results of the maximum density value acquisition in the image forming system according to the present embodiment. FIG. 9 is a diagram for explaining an example of the relationship between 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.

Embodiments of an image forming apparatus, an image forming system, and an image forming method are described in detail below with reference to the attached drawings.

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 has a client PC (Personal Computer) 101, a DFE (Digital Front End) 102, an image forming device 103, and a management server 104.

The client PC 101 creates a print job that the user wants to print, and transmits the print job to the DFE 102 or the management server 104. The client PC 101 is equipped with a display unit such as an LCD display, and input devices including a mouse and a keyboard.

The DFE 102 receives a print job from the client PC 101 or the management server 104, and creates drawing data using an RIP engine based on the received print job. The DFE 102 then transmits the drawing data to the image forming device 103.

The image forming device 103 forms an image based on the drawing data received from the DFE 102. When a reading instruction is received, the image forming device 103 reads the image using an inline sensor installed inside the image forming device 103.

The management server 104 manages print jobs received from the client PC 101. In addition, the management server 104 transmits print jobs to the DFE 102 upon request from the DFE 102.

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

The CPU 201 uses the RAM 203 as a working 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 read by the CPU 201 and used when executing the programs. The I/F 205 is an interface that enables communication between the DFE 102 and the client PC 101, the image forming device 103, and the management server 104.

Figure 3 is a diagram showing an example of the hardware configuration of an image forming device according to this embodiment. As shown in Figure 3, the image forming device 103 according to this embodiment has a CPU 301, a ROM 302, a RAM 303, a HDD/SSD 304, an I/F 305, an image forming unit 306, and a reading unit 307.

The CPU 301 uses the RAM 303 as a working area and executes the programs stored in the ROM 302 to control the operation of the entire image forming apparatus 103. 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 read by the CPU 301 and used when executing the programs.

The I/F 305 is an interface that enables communication between the image forming device 103, the DFE 102, the client PC 101, and the management server 104. The image forming unit 306 is a print engine that forms a print image on printing paper (an example of a recording medium). The reading unit 307 is a reading device (an example of an inline sensor) that reads the print 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 feeding unit that can feed printing paper to the image forming unit 306.

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

The image processing unit 401 issues a start notification when starting the image processing function, and performs image processing when a print job is executed.

The maximum density control unit 402 is a control unit that calculates information related to the maximum density value when the image forming system 1 is executed, and performs a judgment on whether to change the calculated maximum density value. Specifically, the maximum density control unit 402 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 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 to be corrected according to the calculated correction amount.

Then, when a change occurs in the maximum density setting, the maximum density control unit 402 notifies the maximum paper density setting control unit 404 of the maximum density setting. This allows the data required to correct the maximum density value to be calculated using color information (patch information) obtained by reading the gradation correction pattern, and density correction and gradation correction to be performed using the gradation correction pattern. As a result, highly accurate density correction and gradation correction can be achieved simultaneously using the patch information obtained by the reading unit 307 mounted inside the image forming unit 306.

The image correction process control unit 403 is a control unit that calculates a correction curve such as a gradation correction curve for performing color correction such as gradation correction based on the target value and color measurement value (data of the read image processing unit 408) for performing color correction processing, and applies the calculated correction curve to the print job. Specifically, the image correction process control unit 403 uses a gradation correction pattern to perform both density correction and gradation correction of the image forming unit 306. In addition, after updating the maximum density setting included in the paper setting by the paper maximum density setting control unit 404 described later, the image correction process control unit 403 again uses the gradation correction pattern to perform both density correction and gradation correction of the image forming unit 306.

The image correction process control unit 403 also includes a storage unit that stores the gradation correction target value and gradation correction data (gradation correction curve) for each recording medium such as paper, in addition to the process color, for special colors. In addition, in this embodiment, the image correction process control unit 403 includes a special color toner determination control unit that uses the gradation correction data corresponding to the special color for gradation correction when the color used in the image forming unit 306 is switched to a special color.

The maximum paper density setting control unit 404 is a control unit that stores paper settings and changes and saves the paper settings. Furthermore, when the maximum density setting is changed, the maximum paper density setting control unit 404 saves the changed maximum density setting in the paper setting. In other words, after the maximum density setting is changed, the maximum paper density setting control unit 404 updates the maximum density setting included in the paper setting. Furthermore, the maximum paper density setting control unit 404 manages (e.g., stores) the maximum density target value, maximum density setting, gradation correction data, and recording media such as paper in association with each other.

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 judgment and color correction processing. Specifically, when performing gradation correction processing, the read image processing unit 408 converts the patch information (an example of read information) of the gradation correction pattern by the reading unit 307 into density values.

As shown in FIG. 4, the image forming device 103 according to this embodiment has an image forming control unit 405, a reading control unit 406, and a read image acquisition unit 407.

The image forming control unit 405 is a control unit that forms images of print jobs and charts. Specifically, the image forming control unit 405 forms images using the maximum density setting included in the paper settings.

When automatic calibration is performed, the reading control unit 406 controls the reading unit 307 while the print paper is being transported to read the image of the automatic calibration chart (an example of a pattern for gradation correction).

The read image acquisition unit 407 acquires patch information while the print paper is being transported. Here, the patch information is information about the patches contained in the chart for automatic calibration that is read by the reading unit 307. The patch information is also used for color correction processing. Therefore, the read image acquisition unit 407 stores the patch information together and transfers the patch information to the read image processing unit 408.

In this embodiment, DFE 102 and image forming device 103 work together to function as an example of an image forming device, but this is not limited to this, and it is also possible for image forming device 103 alone to function as an example of an image forming device.

Figure 5 is a flowchart showing an example of the flow of maximum density value adjustment processing and automatic calibration performed in the image forming system according to this embodiment.

When an instruction to perform automatic calibration is given to perform color correction processing of the image forming device 103, the image forming control unit 405 of the image forming device 103 controls the image forming unit 306 to print (form an image of) an automatic calibration pattern including a chart for automatic calibration on printing paper (step S501).

When performing automatic calibration, the reading control unit 406 of the image forming device 103 controls the reading unit 307 mounted inside the image forming device 103 to read the image output pattern (chart for automatic calibration) being printed (step S502). Next, the read image acquisition unit 407 of the image forming device 103 acquires patch information of the read image output pattern while the print paper is being transported. Furthermore, the read image acquisition unit 407 converts the acquired patch information (sensor information) into a density value (step S503).

Next, the maximum density control unit 402 of the DFE 102 determines whether or not 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 adjustment of the target maximum density value is not necessary (step S504: No).

In this case, the image correction process control unit 403 of the DFE 102 generates a gradation correction curve, which is a correction curve for performing gradation correction, based on the patch information obtained by reading the image output pattern (step S505). Furthermore, the image correction process control unit 403 applies the generated gradation correction curve to the print job (step S506). Thereafter, the image formation control unit 405 of the image forming device 103 performs image output (printing) of the print image on the printing paper in accordance with the print job (step S507).

On the other hand, if the maximum density value among the converted density values does not reach the target maximum density value, the maximum density control unit 402 of the DFE 102 determines that the target maximum density value needs to be adjusted (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). Furthermore, the maximum density control unit 402 changes the maximum density value according to the calculated correction amount (step S509). Thereafter, the paper maximum density setting control unit 404 of the DFE 102 saves the maximum density setting according to the changed maximum density value in the paper settings (step S510).

Figure 6 is a diagram showing an example of a chart for automatic calibration printed when automatic calibration is performed by the image forming apparatus according to this embodiment. In this embodiment, the chart for automatic calibration is a chart in which patches of engine solid density (maximum density value) of each color toner (e.g., patches C1, M1) are sparsely arranged on the surface of the printing paper and printed on multiple pages, as shown in Figure 6. This makes it possible to create a chart that can correct unevenness in density values on the surface of the printing paper and unevenness in density values between pages.

In addition, by including a patch of the maximum density value in the chart for automatic calibration, there is no need 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. It is also possible to make precise corrections to the maximum density value, taking into account unevenness in density values within the plane of the printing paper in the image forming device 103 and unevenness in density values between pages.

Figure 7 is a diagram for explaining an example of a display screen including the results of automatic calibration and the results of obtaining the maximum density value in the image forming system according to the present embodiment. In the present embodiment, the chart for automatic calibration includes multiple patches for gradation correction in addition to the patch of the maximum density value. Therefore, the read image acquisition unit 407 of the image forming device 103 acquires patch information for the patch for gradation correction in addition to the patch information for the patch of the maximum density value. Therefore, according to the image forming system according to the present embodiment, a graph is obtained showing the relationship between the density value (measured value) converted from the patch information and the relative value (%) of the target density value.

Therefore, in this embodiment, the client PC 101 displays a display screen that includes a graph (the result of automatic calibration) showing the relationship between the measured value and the relative value, as well as the target maximum density value, the density value (measured value), the notch setting (maximum density setting), and a judgment item as to whether the maximum density value meets the target maximum density value.

In addition, if there is a color plate (e.g., black K) whose maximum density value does not satisfy the target maximum density value, the client PC 101 may include on the display screen a message indicating that the target maximum density value is not satisfied. Furthermore, the client PC 101 may include on the display screen a re-execute button that instructs the re-execution of automatic calibration. When the re-execute button included on the display screen of the client PC 101 is pressed, the image forming apparatus 103 prints a chart for automatic calibration with the maximum density setting updated. By pressing the re-execute button, the user can instruct the re-execution of the adjustment of the maximum density value.

Figure 8 is a diagram for explaining another example of a display screen including the results of automatic calibration and the results of obtaining maximum density values in the image forming system according to the present embodiment. If there is a color plate (e.g., black K) whose maximum density value does not meet the target maximum density value, and automatic calibration is re-executed and the maximum density values of all color plates meet the target maximum density value, client PC 101 displays a display screen including a judgment item indicating that the maximum density values of all color plates meet the target maximum density value. In this case, since there is no need to re-execute automatic calibration, client PC 101 displays the re-execute button on the display screen in a state in which it cannot be pressed.

Figure 9 is a diagram for explaining an example of the relationship between the maximum density setting, the target maximum density value, and the read information (maximum density value) in the image forming system according to this embodiment. The paper setting includes a maximum density setting for adjusting the maximum density value when the print image is printed by the image forming device 103. If the maximum density value of the print 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 change the maximum density setting included in the paper setting to increase or decrease the maximum density value when the print image is output by the image forming device 103.

Specifically, the maximum density control unit 402 of the DFE 102 calculates difference information between the target maximum density value and the maximum density value for a 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 that satisfies the target maximum density value when correcting the maximum density value from the next time onwards. Furthermore, even if the maximum density value has changed due to changes over time, it becomes possible to notice that the maximum density value has changed when automatic calibration is performed, and automatic calibration can be performed with the optimal maximum density value.

In this way, according to the image forming system 1 of the present embodiment, the color information (patch information) obtained by reading the gradation correction pattern is used to calculate the data required to correct the maximum density value, and the gradation correction pattern is used to perform density correction and gradation correction. 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.

In the above embodiment, the image forming device of the present invention is described as being applied to a multifunction device having at least two of the following functions: copy function, printer function, scanner function, and facsimile function. However, the image forming device can be applied to any image forming device, such as a copier, printer, scanner device, or facsimile device.

101 Client PC
102 DFE
Reference Signs List 103 Image forming apparatus 104 Management server 401 Image processing section 402 Maximum density control section 403 Image correction processing control section 404 Maximum paper density setting control section 405 Image formation control section 406 Reading control section 407 Read image acquisition section 408 Read image processing section

Patent No. 3885058

Claims (6)

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 an image of a gradation correction pattern;
an image correction processing control unit that uses the gradation correction pattern to execute both density correction and gradation correction for the image forming unit;
a reading control unit that controls the in-line sensor to read the gradation correction pattern;
a read image processing unit that converts read 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 for the maximum density value based on a maximum density value and a target maximum density value among the density values, and changes a maximum density setting included in a paper setting for which the correction is performed in accordance with the correction amount;
a maximum paper density setting control unit that updates the maximum density setting included in the paper setting after the maximum density setting is changed;
The image correction process 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. The image forming device according to claim 1, wherein the gradation correction pattern is a pattern in which the patches of the maximum density value are sparsely arranged on the surface of a recording medium and are printed on multiple recording media. The image forming device according to claim 1 or 2, wherein the maximum paper density setting control unit further manages the target value of the maximum density of the image forming unit, the maximum density setting, the gradation correction data, and the recording medium in association with each other. The image correction processing control unit
a storage unit for storing gradation correction target values and gradation correction data for each recording medium for special colors in addition to process colors;
a special color toner determination control unit that uses the gradation correction data corresponding to the special color for gradation correction when the color used in the image forming unit is switched to the special color;
The image forming apparatus according to claim 1 , further comprising: 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 an image of a gradation correction pattern;
an image correction processing control unit that uses the gradation correction pattern to execute both density correction and gradation correction for the image forming unit;
a reading control unit that controls the in-line sensor to read the gradation correction pattern;
a read image processing unit that converts read 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 for the maximum density value based on a maximum density value and a target maximum density value among the density values, and changes a maximum density setting included in a paper setting for which the correction is performed in accordance with the correction amount;
a maximum paper density setting control unit that updates the maximum density setting included in the paper setting after the maximum density setting is changed;
The image correction process control unit, after updating the maximum density setting, again uses the gradation correction pattern to execute both density correction and gradation correction of the image forming unit. An image forming method executed in an image forming apparatus including an image forming unit and an in-line sensor mounted inside the image forming unit,
an image forming control unit controls an image forming unit to form an image of a gradation correction pattern;
an image correction processing control unit performing both density correction and gradation correction of the image forming unit by using the gradation correction pattern;
a reading control unit controlling an in-line sensor mounted inside the image forming unit to read the gradation correction pattern;
a step of converting read information of the gradation correction pattern by the in-line sensor into a density value when a read image processing unit performs a gradation correction process;
a step of a maximum density control unit calculating a correction amount for the maximum density value based on a maximum density value among the density values and a target maximum density value, and changing a maximum density setting included in a paper setting to be corrected in accordance with the correction amount;
a step of updating the maximum density setting included in the paper setting by a paper maximum density setting control unit after changing the maximum density setting;
the image correction processing control unit, after updating the maximum density setting, again uses the gradation correction pattern to execute both density correction and gradation correction of the image forming unit;
An image forming method comprising the steps of:

Images