JP6283844B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that forms a toner image on a print medium.

  As an invention related to a conventional image forming apparatus, for example, an abnormal copy quality detection mechanism described in Patent Document 1 is known. The abnormal copy quality detection mechanism compares the image density of the image printed on the copy paper with the image density of the original, and stops the operation of the motor when an abnormality is found.

  By the way, with the abnormal copy quality detection mechanism described in Patent Document 1, it is difficult to find an abnormality when the noise level of the image noise is low (that is, the image noise is light or small).

JP 60-247659 A

  Accordingly, an object of the present invention is to provide an image forming apparatus capable of detecting noise that is difficult to detect.

An image forming apparatus according to an aspect of the present invention includes:
A printing unit that forms a toner image including one or more unit images on one or more print media based on first image data that is one or more page-unit image data ;
A reading unit that reads a toner image formed on the one or more print media to obtain one or more second image data;
A control unit;
With
The controller is
A first extraction unit that extracts one or more first regions each including one or more unit images in the one or more second image data;
By comparing each of the first regions in the one or more first image data and each of the first regions in the one or more second image data, the one or more second image data A second extraction unit for extracting first noise included in each first region;
Whether or not a second noise having a level lower than the first noise is generated in the one or more second image data based on the first noise included in each first region. A determination unit for determining;
Including
It is characterized by.

  According to the present invention, it is possible to detect noise that is difficult to detect.

1 is a diagram illustrating an overall configuration of an image forming apparatus 1. 3 is an external perspective view of a reading unit 22. FIG. It is a figure showing density unevenness in the main scanning direction. It is the figure which showed the density nonuniformity of the subscanning direction. It is the figure which showed the example of jumping. It is the figure which showed the example of line weighting. FIG. 6 is a diagram illustrating image data D2 obtained by reading a sheet on which a toner image is printed. It is the figure which showed area | region A7 in the image data D2. It is the figure which showed area | region A7 in the image data D1. It is the figure which showed the noise component n7 contained in area | region A7 in the image data D2. It is a figure explaining the length of the outer edge of the unit image which consists of a character A. It is a figure explaining the length of the outer edge of the unit image which consists of a character I. It is the figure which divided | segmented image data D2 into area | region B1-B3. It is the figure which divided | segmented image data D2 into area | region C1-C4. 6 is a graph showing noise information Nx1 to Nx3 of regions B1 to B3 when density unevenness in the main scanning direction occurs. It is the graph which showed the noise information Ny1-Ny4 of area | region C1-C4 when the density nonuniformity of the subscanning direction has generate | occur | produced. It is a flowchart of the operation | movement which the control part 30 performs at the time of determination of density nonuniformity. It is the figure which showed area | region An which concerns on a modification. It is the figure which showed area | region C1, C2 which concerns on a modification.

  Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Configuration of image forming apparatus)
Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram illustrating an overall configuration of the image forming apparatus 1. FIG. 2 is an external perspective view of the reading unit 22. In FIG. 1, the left-right direction of the paper surface is simply referred to as the left-right direction, the front-rear direction of the paper surface is simply referred to as the front-rear direction, and the up-down direction of the paper surface is simply referred to as the up-down direction.

  The image forming apparatus 1 is an electrophotographic color printer and is configured to synthesize images of four colors (Y: yellow, M: magenta, C: cyan, K: black) in a so-called tandem system. is there. The image forming apparatus 1 has a function of forming an image on a sheet (printing medium) based on image data read by a scanner. As shown in FIG. 1, the printing unit 2, a paper feed cassette 15, a timing roller, and the like. A pair 19, a fixing device 20, a paper discharge roller pair 21, a reading unit 22, a paper discharge tray 23, a control unit 30, and a touch panel 32 are provided.

  The control unit 30 is configured by a CPU, for example, and controls the operation of the image forming apparatus 1.

  The paper feed cassette 15 can store a plurality of sheets and supplies the sheets one by one. The timing roller pair 19 conveys the paper while adjusting the timing so that the toner image is secondarily transferred to the paper in the printing unit 2.

  Based on the control of the control unit 30, the printing unit 2 transfers the toner image to the sheet conveyed by the timing roller pair 19 based on the image data D1. Note that the operation of forming a toner image on the paper by the printing unit 2 is common and will not be described.

  The sheet on which the toner image is transferred is conveyed to the fixing device 20. The fixing device 20 fixes the toner image on the paper by performing heat treatment and pressure treatment on the paper.

  The paper discharge roller pair 21 discharges the paper that has passed through the fixing device 20 onto the paper discharge tray 23. Printed sheets are stacked on the discharge tray 23.

  The reading unit 22 is provided between the fixing device 20 and the paper discharge roller pair 21 and automatically reads the toner image immediately after the printing unit 2 has formed on the paper to acquire the image data D2. As shown in FIG. 2, the reading unit 22 includes conveyance roller pairs 40 and 42, a sensor 46, and a conveyance roller 48.

  The sensor 46 is an inline image sensor that is provided on the upper side of the conveyance roller 48 and reads a toner image printed on the upper surface of the paper. The sensor 46 is a line sensor having a resolution of 600 dpi extending in the front-rear direction (a direction orthogonal to the sheet conveyance direction). The sensor 46 may be a single-color sensor, but is preferably an RGB color sensor that can convert to a YMCK color value.

  The conveyance roller pair 40 is provided on the right side with respect to the sensor 46 and the conveyance roller 48 and conveys the sheet in the left direction. The conveyance roller pair 42 is provided on the left side with respect to the sensor 46 and the conveyance roller 48 and conveys the sheet in the left direction.

  The touch panel 32 is an input device and a display device of the image forming apparatus 1.

(Operation of image forming apparatus)
Hereinafter, the operation of the image forming apparatus 1 will be described. FIG. 3 is a diagram showing density unevenness in the main scanning direction. FIG. 4 is a diagram showing density unevenness in the sub-scanning direction.

  In the image forming apparatus 1, the density unevenness in the main scanning direction shown in FIG. 3 and the density unevenness in the sub-scanning direction shown in FIG. 4 can occur. Density unevenness in the main scanning direction is a phenomenon in which the density differs between the left and right sides of the paper (corresponding to front and rear in FIG. 1). In FIG. 3, the density decreases from the left to the right of the paper. In the following, in FIG. 3, a portion with a relatively high density is called a high density portion E1, and a portion with a relatively low density is called a low density portion E2. Density unevenness appearing in the main scanning direction (hereinafter referred to as density unevenness in the main scanning direction) mainly occurs when the position of the developing roller of the printing unit 2 is biased.

  Further, the density unevenness in the sub-scanning direction is a phenomenon in which the density changes periodically on the top and bottom of the paper (corresponding to the left and right in FIG. 1). In FIG. 4, the density varies periodically as it goes from the top to the bottom of the paper. In the following, in FIG. 4, a portion having a relatively high density is referred to as a high density portion E3, and a portion having a relatively low density is referred to as a low density portion E4. Density unevenness appearing in the sub-scanning direction (hereinafter referred to as density unevenness in the sub-scanning direction) mainly occurs when there is eccentricity or driving unevenness of the developing roller of the printing unit 2.

  The density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction as described above have only a low noise level (noise is light or small). Therefore, it is difficult to detect by the sensor 46. Accordingly, as described below, the image forming apparatus 1 uses noise and line weight that is a noise having a higher noise level than the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction. Density unevenness and density unevenness in the sub-scanning direction are detected. FIG. 5 is a diagram showing an example of jumping. FIG. 6 is a diagram illustrating an example of line weighting.

  As shown in FIG. 5, the jumping phenomenon is a phenomenon in which toner adheres randomly around the toner image. Jumping occurs when toner moves from the photosensitive drum to the intermediate transfer belt on the upstream side of the transfer portion where the photosensitive drum and the intermediate transfer belt are close to each other. Line thickening is a phenomenon in which a character or line toner image is printed thickly as shown in FIG.

  The irregularity or line thickening is noticeable when toner images are formed in the high density portions E1 and E3 having relatively high density in the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction. On the other hand, jumping or line thickening hardly appears even when toner images are formed in the low density portions E2 and E4 having relatively low density in the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction.

  Therefore, the image forming apparatus 1 detects density unevenness in the main scanning direction and density unevenness in the sub-scanning direction by detecting noise such as skipping or line thickening. Accordingly, the image forming apparatus 1 can determine that the portion where the jumping or line thickening has occurred is the high density portions E1 and E3, and the portion where the jumping or line thickening has not occurred is the low density portions E2 and E4. FIG. 7 is a diagram showing image data D2 obtained by reading a sheet on which a toner image is printed.

  As shown in FIG. 7, the toner image formed on the sheet includes a plurality (12) of unit images. A unit image is a character, symbol, or line image. One unit image means one character, one symbol, or one line. The control unit 30 extracts regions A1 to An (n is a natural number, 12 in FIG. 7) each including one unit image in the image data D2 of FIG. In the present embodiment, the regions A1 to An are rectangular.

  Next, the control unit 30 extracts the noises N1 to Nn included in the areas A1 to An in the image data D2 by comparing the areas A1 to An in the image data D1 with the areas A1 to An in the image data D2. . The image data D1 is data used when a toner image is printed on a sheet, and does not include noise. As an example, extraction of noise N7 will be described below with reference to the drawings. FIG. 8 is a diagram showing a region A7 in the image data D2. FIG. 9 is a diagram showing a region A7 in the image data D1. FIG. 10 is a diagram showing the noise component n7 included in the region A7 in the image data D2. FIG. 11 is a diagram for explaining the length of the outer edge of a unit image made up of the letter A. FIG. FIG. 12 is a diagram for explaining the length of the outer edge of a unit image made up of the letter I.

  The control unit 30 calculates the difference between the area A7 in the image data D2 shown in FIG. 8 and the area A7 in the image data D1 shown in FIG. 9 to obtain a noise component n7 shown in FIG. In FIG. 10, there are 12 dots in the area A7. Therefore, the noise component n7 is 12. Further, the control unit 30 calculates the length L7 of the outer edge of the unit image included in the region A7 in the image data D1 shown in FIG. 9, and sets a value obtained by dividing the noise component n7 by the length L7 as the noise N7. . The reason why the noise component n7 is divided by the length L7 will be described below.

  The amount of occurrence of jumping or line thickening (that is, noise component) increases as the length of the outer edge of the unit image increases. A case where a unit image composed of letters A or I is formed in the high density portions E1 and E3 will be described as an example. As shown in FIGS. 11 and 12, A has a longer outer edge than I. Therefore, even if the densities of the high density portions E1 and E3 are the same, the amount of occurrence of chattering or line thickening when occurring in the unit image consisting of the letter A causes the chattering or lineing when occurring in the unit image consisting of the letter I. It is larger than the amount of fat. In this case, it is difficult to accurately calculate the density of the high density portions E1 and E3 from the noise component. Therefore, the control unit 30 sets a value obtained by dividing the noise component n7 by the length L7 of the outer edge of the unit image as noise N7. As shown in FIG. 10, since 12 dots exist as the noise component n7 in the area A7, the noise N7 is 12 / L7.

  Next, the control unit 30 divides the image data D2 into a plurality of regions B1 to Bm (m is a natural number) or regions C1 to Co (o is a natural number) larger than the regions A1 to An. Hereinafter, the division of the regions B1 to Bm or the regions C1 to Co will be described with reference to the drawings. FIG. 13 is a diagram in which the image data D2 is divided into regions B1 to B3. FIG. 14 is a diagram in which the image data D2 is divided into regions C1 to C4.

  As shown in FIG. 13, the control unit 30 divides the image data D2 into regions B1 to B3. The areas B1 to B3 have a rectangular shape extending in the paper transport direction (vertical direction in FIG. 13, sub-scanning direction), and are arranged in the horizontal direction (main scanning direction). The region B1 includes regions A1, A4, A7, and A10. The region B2 includes regions A2, A5, A8, and A11. The region B3 includes regions A3, A6, A9, and A12.

  Next, the control unit 30 generates noise information Nx1 to Nx3 related to the sum of the noises N1 to N12 included in the regions A1 to A12 belonging to each of the regions B1 to B3. More specifically, the control unit 30 sets the sum of noises N1, N4, N7, and N10 as noise information Nx1. The control unit 30 sets the sum of noises N2, N5, N8, and N11 as noise information Nx2. The control unit 30 sets the sum of noises N3, N6, N9, and N12 as noise information Nx3.

  Further, as shown in FIG. 14, the control unit 30 divides the image data D2 into regions C1 to C4. The regions C1 to C4 have a rectangular shape extending in the left-right direction (main scanning direction), and are arranged in the transport direction (up-down direction and sub-scanning direction in FIG. 14). The region C1 includes regions A1 to A3. The region C2 includes regions A4 to A6. The region C3 includes regions A7 to A9. The region C4 includes regions A10 to A12.

  Next, the control unit 30 generates noise information Ny1 to Ny4 related to the sum of the noises N1 to N12 included in the regions A1 to A12 belonging to each of the regions C1 to C4. More specifically, the control unit 30 sets the sum of noises N1 to N3 as noise information Ny1. The control unit 30 sets the sum of noises N4 to N6 as noise information Ny2. The control unit 30 sets the sum of the noises N7 to N9 as noise information Ny3. The control unit 30 sets the sum of the noises N10 to N12 as noise information Ny4.

  Next, the control unit 30 determines whether or not density unevenness occurs in the main scanning direction based on the noise information Nx1 to Nx3. Specifically, as shown in the graph of FIG. 15, when the noise information Nx1 to Nx3 is monotonically decreasing or monotonically increasing, the control unit 30 determines that density unevenness in the main scanning direction has occurred. At this time, the control unit 30 compares the noise information Nx1 to Nx3 with the pattern X that is stored in a storage unit (not shown) and that indicates density unevenness in the main scanning direction, thereby comparing the noise information Nx1 to Nx3. The presence / absence of density unevenness is determined. Further, the control unit 30 may store a threshold value of the degree of coincidence with the pattern X in advance in the storage unit, and determine whether density unevenness has occurred in the main scanning direction based on whether the threshold value is exceeded.

  Further, the control unit 30 determines whether or not density unevenness occurs in the sub-scanning direction based on the noise information Ny1 to Ny4. Specifically, as shown in the graph of FIG. 16, when the noise information Ny1 to Ny4 repeats increasing and decreasing, the control unit 30 determines that density unevenness in the sub-scanning direction has occurred. At this time, the control unit 30 compares the noise information Ny1 to Ny4 with the pattern Y that is stored in the storage unit (not shown) and indicates the density unevenness in the sub-scanning direction, and thereby the sub-scanning direction. The presence / absence of density unevenness is determined. Further, the control unit 30 may store a threshold value of the degree of coincidence with the pattern Y in the storage unit in advance, and determine whether or not density unevenness occurs in the sub-scanning direction depending on whether or not the threshold value is exceeded.

  Finally, the control unit 30 causes the printing unit 2 to execute an image quality adjustment mode (image stabilization processing) based on the occurrence of density unevenness in the main scanning direction and density unevenness in the sub-scanning direction. Furthermore, the control unit 30 displays the determination result on the touch panel 32 and notifies the user of the determination result.

  As described above, the control unit 30 has density unevenness in the main scanning direction having a noise level lower than noise such as jumping or line thickening based on noise such as jumping or line thickening included in the areas A1 to A12. Alternatively, it is determined whether noise such as density unevenness in the sub-scanning direction is generated in the image data D2.

  Next, an operation performed when the image forming apparatus 1 determines density unevenness will be described with reference to the drawings. FIG. 17 is a flowchart of the operation performed by the control unit 30 when determining density unevenness.

  First, the control unit 30 causes the reading unit 22 to read a toner image and obtains image data D2 (step S1).

  Next, as shown in FIG. 7, the control unit 30 extracts regions A1 to A12 including the unit image from the image data D2 (step S2).

  Next, the control unit 30 calculates the difference between the region An in the image data D2 shown in FIG. 8 and the region An in the image data D1 shown in FIG. 9 to obtain the noise component nn shown in FIG. 10 (step S3). .

  Next, the control unit 30 calculates the length Ln of the outer edge of the unit image included in the region An (step S4).

  Next, the control unit 30 calculates the noise Nn by dividing the noise component nn by the length Ln (step S5).

  Next, the control unit 30 determines whether or not the calculation of the noises N1 to N12 of all the regions A1 to A12 has been completed (step S6). When the calculation of all the noises N1 to N12 is completed, the process proceeds to step S7. If calculation of all the noises N1 to N12 has not been completed, the process returns to step S3. In this case, steps S3 to S6 are repeated until calculation of all the noises N1 to N12 is completed.

  When the calculation of all the noises N1 to N12 is completed, the control unit 30 generates regions B1 to B3 as shown in FIG. 13 (step S7). And the control part 30 totals noise information Nx1-Nx3 using noise N1-N12 (step S8). Specifically, the control unit 30 sets the sum of noises N1, N4, N7, and N10 as noise information Nx1, sets the sum of noises N2, N5, N8, and N11 as noise information Nx2, and sets noises N3, N6, N9, and N12. Is the noise information Nx3.

  Next, the control unit 30 generates regions C1 to C4 as shown in FIG. 14 (step S9). And the control part 30 totals noise information Ny1-Ny4 using noise N1-N12 (step S10). Specifically, the control unit 30 sets the sum of noises N1 to N3 as noise information Ny1, sets the total of noises N4 to N6 as noise information Ny2, sets the total of noises N7 to N9 as noise information Ny3, and sets noises N10 to N12. Is the noise information Ny4.

  Next, the control unit 30 determines whether density unevenness has occurred in the image data D2 based on the noise information Nx1 to Nx3 and Ny1 to Ny4 (step S11). When the change in the noise information Nx1 to Nx3 is monotonously decreasing or monotonically increasing, the control unit 30 determines that density unevenness has occurred in the main scanning direction. Further, when the changes in the noise information Ny1 to Ny4 are repeatedly increasing and decreasing, the control unit 30 determines that density unevenness has occurred in the sub-scanning direction. If density unevenness has occurred, the process proceeds to step S12. If there is no density unevenness, this process ends.

  When density unevenness has occurred, the control unit 30 causes the printing unit 2 to execute image stabilization processing (step S12). Thereby, density unevenness is reduced.

(effect)
The image forming apparatus 1 according to the present embodiment can detect density unevenness that is difficult to detect. More specifically, the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction have only a low noise level (noise is light or small). Therefore, it is difficult to detect by the sensor 46. Therefore, the image forming apparatus 1 makes the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction obvious by using skipping or line thickening. The irregularity or line thickening is noticeable when toner images are formed in the high density portions E1 and D3 having relatively high density in the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction. On the other hand, jumping or line thickening hardly appears even when toner images are formed in the low density portions E2 and D4 where the density is relatively low in the density unevenness in the main scanning direction and the density unevenness in the sub-scanning direction.

  Therefore, the image forming apparatus 1 detects density unevenness in the main scanning direction and density unevenness in the sub-scanning direction by detecting noise such as skipping or line thickening. Accordingly, the image forming apparatus 1 can determine that the portion where the jumping or line thickening has occurred is the high density portions E1 and E3, and the portion where the jumping or line thickening has not occurred is the low density portions E2 and E4.

  Further, in the image forming apparatus 1, the control unit 30 can detect the occurrence of density unevenness, so that the printing unit 2 can execute the image stabilization process at an appropriate timing. For this reason, it is possible to suppress the useless image stabilization processing and to improve the productivity of the image forming apparatus 1.

  The image forming apparatus 1 is also suitable for detecting random noise without reproducibility, in addition to detecting density unevenness in the main scanning direction and density unevenness in the sub-scanning direction.

(First modification)
Below, area | region A1-A12 which concerns on a modification is demonstrated. FIG. 18 is a diagram illustrating a region An according to a modification.

  Whereas the area An according to the embodiment has a rectangular shape, the area An according to the modification has a shape along the outer edge of the unit image. Specifically, the region An is a region within a certain distance from the outer edge of the unit image.

(Second modification)
Below, the area | region Cn which concerns on a modification is demonstrated. FIG. 19 is a diagram illustrating regions C1 and C2 according to the modification.

  The upper image data in FIG. 19 is referred to as image data D2-1, and the lower image data in FIG. 19 is referred to as image data D2-2. Image data D2-1 and D2-2 are image data obtained by reading by the reading unit 22. In addition, areas A1-1 to A12-1 are set in the image data D2-1. Regions A1-2 to A12-2 are set in the image data D2-2.

  The area C1 includes substantially the entire surface of the image data D2-1 and includes areas A1-1 to A12-1. The area C2 includes substantially the entire surface of the image data D2-2, and includes areas A1-2 to A12-2. Therefore, the control unit 30 generates noise information Ny1 related to the sum of the noise components n1-1 to n12-1 of the regions A1-1 to A12-1 included in the image data D2-1, and the image data D2-2. Noise information Ny2 related to the sum of the noise components n1-2 to n12-2 of the included regions A1-2 to A12-2 is generated.

  Further, the control unit 30 determines whether or not density unevenness in the sub-scanning direction occurs across the image data D2-1 and D2-2 based on the noise information Ny1 and Ny2.

  According to the image forming apparatus 1 as described above, it is possible to detect density unevenness in the sub-scanning direction that occurs across a plurality of sheets.

(Other embodiments)
The image forming apparatus according to the present invention is not limited to the image forming apparatus 1, and can be changed within the scope of the gist thereof.

  Note that the control unit 30 may use a value obtained by dividing the sum of the noises N1, N4, N7, and N10 by the number of the regions A1, A4, A7, and A10 included in the region B1 as the noise information Nx1. The same applies to the noise information Nx2, Nx3, Ny1 to Ny4.

  Moreover, although the control part 30 makes noise N1-N12 the value obtained by dividing noise component n1-n7 by the length L1-L12 of the outer edge of a unit image, noise component n1-n7 also makes noise N1-N12. Good.

  Note that the reading unit 22 may be an image sensor or a flatbed scanner arranged in an ADF provided in the image forming apparatus 1.

  The areas A1 to An may include a plurality of unit images.

  Note that the control unit 30 does not set the regions B1 to Bm and C1 to Co, and the density unevenness in the main scanning direction or the sub scanning direction is caused by the image data D2 based on the noises N1 to Nn included in the regions A1 to An. It may be determined whether or not it has occurred.

  The image forming apparatus according to the present invention is excellent in that noise that is difficult to detect can be detected.

1: Image forming apparatus 2: Printing unit 15: Paper cassette 19: Timing roller pair 20: Fixing device 21: Paper discharge roller pair 22: Reading unit 23: Paper discharge tray 30: Control unit 32: Touch panel

Claims (13)

A printing unit that forms a toner image including one or more unit images on one or more print media based on first image data that is one or more page-unit image data ;
A reading unit that reads a toner image formed on the one or more print media to obtain one or more second image data;
A control unit;
With
The controller is
A first extraction unit that extracts one or more first regions each including one or more unit images in the one or more second image data;
By comparing each of the first regions in the one or more first image data and each of the first regions in the one or more second image data, the one or more second image data A second extraction unit for extracting first noise included in each first region;
Whether or not a second noise having a level lower than the first noise is generated in the one or more second image data based on the first noise included in each first region. A determination unit for determining;
Including
An image forming apparatus. The controller is
Each of the one or more second image data is divided into a plurality of second regions larger than the first region, and the first region included in the first region belonging to each second region. A generator that generates noise information related to the sum of noise,
In addition,
The determining unit determines whether the second noise is generated in the one or more second image data based on the noise information;
The image forming apparatus according to claim 1. The plurality of second regions have a rectangular shape extending in a direction orthogonal to the transport direction of the print medium, and are arranged so as to be aligned in the transport direction of the print medium.
The image forming apparatus according to claim 2. The determination unit determines whether density unevenness appearing in the transport direction has occurred in the one or more second image data;
The image forming apparatus according to claim 3. The plurality of second regions have a rectangular shape extending in the transport direction of the print medium, and are arranged so as to be aligned in an orthogonal direction orthogonal to the transport direction of the print medium.
The image forming apparatus according to claim 2. The determination unit determines whether density unevenness appearing in the orthogonal direction occurs in the one or more second image data;
The image forming apparatus according to claim 5. The second extraction unit obtains a difference between each first region in the one or more first image data and each first region in the one or more second image data, Extracting a first noise included in each first region in one or more second image data;
The image forming apparatus according to any one of claims 1 to 6, characterized in. The second extraction unit calculates a difference between each first region in the one or more first image data and each first region in the one or more second image data, and each first region. A value obtained by dividing by the length of the outer edge of the unit image included in the region is the first noise,
The image forming apparatus according to any one of claims 1 to 6, characterized in. The first region is a region within a certain distance from an outer edge of the unit image;
The image forming apparatus according to any one of claims 1 to 8, characterized in. The unit image is a character, a symbol, or a line image;
The image forming apparatus according to any one of claims 1 to 9, characterized in. The reading unit automatically reads a toner image immediately after the printing unit prints on the print medium;
The image forming apparatus according to any one of claims 1 to 10, characterized in. The controller is
Based on the determination result of the determination unit, a print control unit that causes the printing unit to execute an image quality adjustment mode,
Including further,
The image forming apparatus according to any one of claims 1 to 11, characterized in. A notification unit that notifies the user of the determination result,
More
The image forming apparatus according to any one of claims 1 to 12, characterized in.