JP2018040924A - Image forming apparatus and image forming program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that has reliably corrected density unevenness of a 100% density area by ensuring a correction range compared with a case where the image forming apparatus corrects density unevenness with a single correction method, and an image forming program.SOLUTION: An image forming apparatus starts forming a test image of a 100% density area to detect a developing bias of an AC power supply (100, 102), calculates information on correction of a developing bias of a DC power supply on the basis of the detected developing bias of the AC power supply and sets the correction information to a correction control part (104), subsequently forms a test image of the other density area than the 100% density area by using the correction information (106), and detects the density of the test image (108). When the density unevenness does not fall within a permissible range, the image forming apparatus corrects the density unevenness by correcting image information (110, 112).SELECTED DRAWING: Figure 3

Description

  The present invention relates to an image forming apparatus and an image forming program.

  Patent Document 1 proposes an image forming apparatus that corrects density unevenness by forming a test image, detecting density unevenness, and correcting the development bias and charging bias.

JP 2013-125132 A

  In an electrophotographic image forming apparatus, it is possible to correct density unevenness by correcting charging bias, correcting exposure amount, correcting developing bias, or correcting image information. However, the correction method is limited for the 100% density range. In some cases, the density unevenness cannot be corrected with either of them. Therefore, the present invention provides an image forming apparatus and an image forming program capable of ensuring a correction range and correcting density unevenness more reliably in a 100% density range as compared with a case where correction is performed by a single correction method. The purpose is to provide.

  The image forming apparatus according to claim 1, a charging device that charges the image carrier with a charging bias, an exposure device that exposes the charged image carrier to form a latent image represented by image information, and a developing bias. A developing device for developing the latent image to form a toner image on the image carrier, a transfer device for transferring the toner image to a transfer medium, and uneven density of the toner image formed on the transfer medium. By using the detection unit for detecting information and the detection result of the detection unit to correct at least one of the charging bias, the exposure amount of the exposure apparatus, and the development bias, density unevenness in a 100% density range is obtained. A correction unit that corrects density unevenness in a density range other than the 100% density range by correcting the image information after correcting the image information.

  According to a second aspect of the present invention, in the first aspect of the present invention, the correction unit corrects density unevenness in a 100% density range by correcting the exposure amount or the development bias.

  According to a third aspect of the present invention, in the first aspect of the invention, the correction unit corrects density unevenness in a 100% density range by correcting the development bias, and satisfies a predetermined undercorrection condition. In this case, at least one of the charging bias and the exposure amount is further corrected.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the detection unit detects a developing bias of an AC power source of the developing device, so that a 100% density region is obtained. By detecting density unevenness and detecting the density of the toner image or the image transferred to the transfer medium, density unevenness in a density range other than the 100% density range is detected.

  An image forming program according to a fifth aspect causes a computer to function as the detection unit and the correction unit of the image forming apparatus according to any one of the first to third aspects.

  According to the image forming apparatus of claim 1, as compared with the case where correction is performed by a single correction method, image formation is possible in which a correction range is secured and density unevenness can be more reliably corrected even in a 100% density range. Equipment can be provided.

  According to the second aspect of the present invention, it is possible to ensure the correction accuracy when correcting the density unevenness in the 100% density region, compared with the case of correcting the charging bias.

  According to the third aspect of the present invention, it is possible to ensure the correction accuracy when correcting the density unevenness in the 100% density region, as compared with the case of correcting the charging bias and the exposure amount.

  According to the fourth aspect of the present invention, it is possible to detect the density unevenness in accordance with the cause of the density unevenness in the density range, compared to the case where the density unevenness is detected by a single detection method.

  According to the image processing program of claim 5, compared with the case where correction is performed by a single correction method, image formation is possible in which the correction range is secured and density unevenness can be more reliably corrected even in the 100% density range. A program can be provided.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an exemplary embodiment. 2 is a block diagram illustrating a schematic configuration for correcting density unevenness in the image forming apparatus according to the first embodiment. FIG. 6 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in the image forming apparatus according to the first embodiment. FIG. 10 is a block diagram illustrating a schematic configuration for correcting unevenness in an image forming apparatus according to a second embodiment. 10 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in an image forming apparatus according to a second embodiment. FIG. 10 is a block diagram illustrating a schematic configuration for correcting density unevenness in an image forming apparatus according to a third embodiment. 12 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in an image forming apparatus according to a third embodiment.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus 10 according to the present embodiment. In this embodiment, an image forming apparatus that forms a color image by an electrophotographic method will be described as an example.

  As shown in FIG. 1, in the image forming apparatus 10, an endless belt-like intermediate transfer belt 12 is supported by a plurality of rolls 14 with a predetermined tension.

  On the intermediate transfer belt 12, along the belt conveyance X, images of colors corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K) are displayed. Image forming sections 16Y, 16M, 16C, and 16K to be formed are provided in order. In the following description, reference numerals corresponding to the respective colors are omitted unless otherwise specified.

  Each image forming unit 16 is provided with a photosensitive drum 18 as an example of an image holding member corresponding to each color. Each of the photosensitive drums 18 is rotatably supported on an apparatus main body (not shown). Further, around each photosensitive drum 18, along the rotation direction (counterclockwise direction in FIG. 1) of each photosensitive drum 18, a cleaning unit 20, a static eliminator (not shown), a charging device 22, and an exposure device. 24, a developing device 26, and a primary transfer roll 28 as an example of a transfer device are sequentially arranged.

  That is, after the toner remaining on the photosensitive drum 18 is removed by the cleaning unit 20, the charge on the photosensitive drum 18 is neutralized by the static eliminator, the charging bias voltage is applied by the charging device 22, and the photosensitive drum 18 is Charged. Then, the exposure device 24 irradiates and exposes light modulated according to the image to be formed on the surface of the photosensitive drum 18 to form a latent image. The latent image formed by the exposure device 24 is developed by the development device 26 by applying a development bias voltage, and a toner image is formed on the photosensitive drum 18. The toner image formed on the photosensitive drum 18 is transferred onto the intermediate transfer belt 12 by the primary transfer roll 28 by applying a transfer bias voltage. At this time, a color image is formed on the intermediate transfer belt 12 by being transferred onto the intermediate transfer belt 12 so that the toner images formed by the image forming units 16 overlap each other. Note that sub-scanning is performed by the photosensitive drum 18, and main scanning is performed by the exposure device 24.

  Further, the image forming apparatus 10 detects the density of toner images of Y, M, C, and K colors formed on the intermediate transfer belt 12 and measures the density distribution (density unevenness) of the image. The density sensor 30 is disposed downstream of the black image forming unit 16K in the belt conveyance direction (X direction in FIG. 1). As the density sensor 30, for example, a reflection type photosensor arranged in a large number in the main scanning direction can be applied.

  On the other hand, a sheet as an image formation target is accommodated in a sheet feeding unit (not shown), fed out one by one, conveyed along a predetermined path, and sent to the press contact position of the secondary transfer roll 32. Then, after the color image on the intermediate transfer belt 12 is collectively transferred to a sheet as a medium to be transferred by the secondary transfer roll 32, a fixing process (heating, pressing, etc.) is performed by the fixing device 34, and the color image is formed. The formed paper is conveyed from the image forming apparatus 10 and discharged.

  Next, a configuration for correcting density unevenness of the image forming apparatus 10 according to the present embodiment will be described.

(First embodiment)
FIG. 2 is a block diagram illustrating a schematic configuration for correcting density unevenness in the image forming apparatus 10 according to the first embodiment.

  The image forming apparatus 10 according to the present embodiment includes a density unevenness correction unit 40 as an example of a correction unit that corrects density unevenness. In this embodiment, since the four-color image forming unit 16 is provided, the density unevenness correction unit 40 corrects the density unevenness for each color. However, the following description will be given focusing on one image forming unit 16. To do.

  The density unevenness correction unit 40 includes a correction control unit 46 that corrects density unevenness caused by various factors such as eccentricity of the photosensitive drum 18 and the magnetic roll in the developing device 26.

  The correction control unit 46 detects density unevenness and controls the image information correction unit 42 and the development bias correction unit 44 to correct the density unevenness.

  A density sensor 30, an image information correction unit 42, a development bias correction unit 44, and a development bias detection unit 48 are connected to the correction control unit 46. The density sensor 30 and the development bias detector 48 correspond to an example of a detector.

  The detection of density unevenness includes a method in which a test image for each density range formed in advance is detected by the density sensor 30 and a method in which density unevenness is detected by detecting the development bias of the developing device 26 by the development bias detection unit 48. . The former detects density unevenness by directly detecting the density of an image formed on the intermediate transfer belt 12. On the other hand, the latter detects, for example, density unevenness by applying the technique disclosed in Japanese Patent Application Laid-Open No. 2012-252324. Specifically, when the developing bias of the AC power source and the DC power source is applied, the current value of the developing bias of the AC power source is in accordance with the change in the distance between the magnetic roll in the developing device 26 and the photosensitive drum 18. Since it fluctuates, the current value of the developing bias of the AC power supply is detected. Since the change in the distance between the magnetic roll and the photosensitive drum 18 causes the density unevenness, the density unevenness is detected by detecting the current value of the developing bias of the AC power source of the developing device 26. Therefore, the information on the density unevenness is information obtained by forming a test image and directly detecting the density unevenness, as well as information on the density unevenness that can be indirectly detected. The bias current value is also included.

  The image information correction unit 42 corrects image information indicating an image to be formed in order to correct the detected density unevenness. That is, correction information for correcting the image information that suppresses the detected density unevenness is calculated, and the density unevenness is corrected by correcting the image information using the correction information.

  The developing bias correction unit 44 calculates correction information of the developing bias of the developing device 26 for correcting the detected density unevenness, and corrects the developing bias of the developing device 26 using the correction information, thereby correcting the density unevenness. to correct. For example, density unevenness is detected by detecting the distance between the magnetic roll in the developing device 26 and the photosensitive drum 18 from the change in the current value of the developing bias of the AC power supply. Then, the developing bias voltage of the DC power supply that cancels the detected density unevenness is calculated to correct the developing bias voltage of the DC power supply.

  In this embodiment, as a method for correcting density unevenness, a method for correcting image information and a method for correcting a development bias are used. In the correction of image information, a 100% density range (so-called solid image) is used. In some cases, it cannot be corrected. Therefore, the correction control unit 46 controls the development bias correction unit 44 to correct the development bias to correct the density unevenness in the 100% density range, and then controls the image information correction unit 42 to correct the image information. By doing so, density unevenness in other density regions is corrected.

  Next, a process performed when correcting the density unevenness in the image forming apparatus 10 according to the present embodiment will be described. FIG. 3 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in the image forming apparatus 10 according to the first embodiment. Note that the process in FIG. 3 shows a part of the process when correcting the density unevenness. Further, the processing of FIG. 3 may be started at the time of activation, a predetermined timing after each elapse of time, or may be started by an instruction of the user.

  In step 100, the image forming unit 16 starts forming a 100% density region test image, and proceeds to step 102. In this embodiment, since there are four colors of C, M, Y, and K, a predetermined test image in a 100% density region (so-called solid image) is formed for each color, and the following processing is performed for each color. .

  In step 102, the developing bias detector 48 detects the developing bias of the AC power supply of the developing device 26 and proceeds to step 104. For example, the current value of the developing bias of the AC power supply when forming a 100% density region test image is detected. Accordingly, the density unevenness is detected by detecting a change in the distance between the magnetic roll in the developing device 26 and the photosensitive drum 18 that causes the density unevenness.

  In step 104, the development bias correction unit 44 calculates correction information for correcting the development bias of the DC power source based on the development bias of the AC power source detected by the development bias detection unit 48, and sends it to the correction control unit 46. Set and go to step 106. That is, since the change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18 can be known from the change in the development bias of the AC power supply, the correction information of the development bias of the DC power supply that cancels the change in the distance is calculated. Then, the correction control unit 46 is set. The correction control unit 46 corrects the developing bias of the DC power supply of the developing device 26 using the set correction information, thereby causing a change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18. Concentration unevenness is suppressed.

  In step 106, the image forming unit 16 forms a test image in a density region other than the 100% density region using the correction information set in the correction control unit 46, and proceeds to step 108. For example, a test image of a plurality of density ranges such as a 30% density range and an 80% density range is formed.

  In step 108, the density sensor 30 detects the density of the test image, and the process proceeds to step 110. That is, by detecting the density of the test image in a density area other than the 100% density area, density unevenness in a density area other than the 100% density area is detected.

  In step 110, the correction controller 46 determines whether or not the density unevenness of the test image in each density range detected by the density sensor 30 is within a predetermined allowable range. If the determination is negative, the process proceeds to step 112. If the determination is affirmative, the density unevenness is suppressed within a predetermined allowable range by correcting the developing bias, and the process is ended as it is.

  In step 112, the image information correction unit 42 corrects the image information so as to suppress the density unevenness based on the detection result of the density sensor 30, and ends the series of processes. As a result, in the density areas other than the 100% density area, the density unevenness is corrected by correcting the image information.

  As described above, in the present embodiment, the density unevenness in the 100% density region cannot be corrected by the correction of the image information. Therefore, the density unevenness in the 100% density region is corrected by correcting the developing bias of the developing device 26. Then, density unevenness other than the 100% density range is corrected by correcting the image information.

  In addition to correcting the development bias and image information, there is a method for correcting the density unevenness, such as the charging bias of the charging device 22 and the exposure amount of the exposure device 24. However, the correction range cannot be secured by any one of them. There is. In the present embodiment, by correcting as described above, the correction range is secured and the density unevenness is corrected more reliably in the 100% density range.

(Second Embodiment)
FIG. 4 is a block diagram illustrating a schematic configuration for correcting unevenness in the image forming apparatus 10 according to the second embodiment. In addition, about the same structure as 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the first embodiment, the example in which the density unevenness is corrected by correcting each of the image information and the developing bias has been described, but in the second embodiment, each of the image information and the exposure amount of the exposure device 24 is corrected. Correct the uneven density with.

  That is, the second embodiment is different from the first embodiment only in that an exposure amount correction unit 43 is provided instead of the development bias correction unit 44 of the first embodiment, and the other configuration is the same as that of the first embodiment.

  The exposure amount correction unit 43 calculates exposure amount correction information for correcting the detected density unevenness, and corrects the density unevenness by correcting the exposure amount of the exposure device 24 using the correction information.

  In the present embodiment, since the exposure amount of the exposure device 24 is corrected, the possibility that a disturbance will be applied after the correction is performed until the image is developed is higher than in the first embodiment. In consideration of accuracy, it is preferable to correct the developing bias as in the first embodiment.

  Next, a process performed when correcting the density unevenness in the image forming apparatus 10 according to the present embodiment will be described. FIG. 5 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in the image forming apparatus 10 according to the second embodiment. The process of FIG. 5 shows a part of the process when correcting the density unevenness, and the same processes as those in the first embodiment are denoted by the same reference numerals. Further, the processing of FIG. 5 may be started at the time of activation, at a predetermined timing after each elapse of time, or may be started in accordance with a user instruction.

  In step 100, the image forming unit 16 starts forming a 100% density region test image, and proceeds to step 102. In this embodiment, since there are four colors of C, M, Y, and K, a predetermined test image in a 100% density region (so-called solid image) is formed for each color, and the following processing is performed for each color. .

  In step 102, the developing bias detector 48 detects the developing bias of the AC power source of the developing device 26 and proceeds to step 105. For example, the current value of the developing bias of the AC power supply when forming a 100% density region test image is detected. Accordingly, the density unevenness is detected by detecting a change in the distance between the magnetic roll in the developing device 26 and the photosensitive drum 18 that causes the density unevenness.

  In step 105, the exposure amount correction unit 43 calculates correction information for correcting the exposure amount of the exposure device 24 based on the development bias of the AC power source detected by the development bias detection unit 48 and calculates the correction control unit 46. And go to Step 106. That is, since the change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18 is known from the change in the developing bias of the AC power supply, exposure amount correction information that cancels out density unevenness due to the change in distance is calculated. , Set in the correction control unit 46. The correction control unit 46 corrects the exposure amount of the exposure device 24 using the set correction information, thereby suppressing uneven density due to a change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18. Is done.

  In step 106, the image forming unit 16 forms a test image in a density region other than the 100% density region using the correction information set in the correction control unit 46, and proceeds to step 108. For example, a test image of a plurality of density ranges such as a 30% density range and an 80% density range is formed.

  In step 108, the density sensor 30 detects the density of the test image, and the process proceeds to step 110. That is, by detecting the density of the test image in a density area other than the 100% density area, density unevenness in a density area other than the 100% density area is detected.

  In step 110, the correction controller 46 determines whether or not the density unevenness of the test image in each density range detected by the density sensor 30 is within a predetermined allowable range. If the determination is negative, the process proceeds to step 112. If the determination is affirmative, the density unevenness is suppressed within a predetermined allowable range by correcting the exposure amount of the exposure device 24, and thus the process ends. .

  In step 112, the image information correction unit 42 corrects the image information so as to suppress the density unevenness based on the detection result of the density sensor 30, and ends the series of processes. As a result, in the density areas other than the 100% density area, the density unevenness is corrected by correcting the image information.

  Thus, instead of correcting the developing bias of the first embodiment, the exposure amount of the exposure device 24 may be corrected.

(Third embodiment)
FIG. 6 is a block diagram illustrating a schematic configuration for correcting density unevenness in the image forming apparatus 10 according to the third embodiment. In addition, about the same structure as 1st Embodiment and 2nd Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the first embodiment, each of the image information and the developing bias is corrected. In the second embodiment, the density unevenness is corrected by correcting each of the image information and the exposure amount of the exposure device 24. However, the third embodiment Is a combination of the first and second embodiments.

  That is, as shown in FIG. 6, an image information correction unit 42, a development bias correction unit 44, and an exposure amount correction unit 43 are connected to the correction control unit 46. In this embodiment, the density unevenness in the 100% density range is corrected by correcting the developing bias, and when the correction is insufficient due to a lack of the correction range, the exposure amount of the exposure device 24 is corrected. Correct density unevenness. For other density regions other than the 100% density region, the density unevenness is corrected by correcting the image information as in the above embodiments.

  Next, a process performed when correcting the density unevenness in the image forming apparatus 10 according to the present embodiment will be described. FIG. 7 is a flowchart illustrating an example of a flow of processing performed when correcting density unevenness in the image forming apparatus 10 according to the third embodiment. The process of FIG. 7 shows a part of the process when correcting the density unevenness, and the same processes as those in the first embodiment will be described with the same reference numerals. Further, the processing of FIG. 7 may be started at the time of activation, a predetermined timing after each elapse of time, or may be started by a user instruction.

  In step 100, the image forming unit 16 starts forming a 100% density region test image, and proceeds to step 102. In this embodiment, since there are four colors of C, M, Y, and K, a predetermined test image in a 100% density region (so-called solid image) is formed for each color, and the following processing is performed for each color. .

  In step 102, the developing bias detector 48 detects the developing bias of the AC power source of the developing device 26 and proceeds to step 103. For example, the current value of the developing bias of the AC power supply when forming a 100% density region test image is detected. Accordingly, the density unevenness is detected by detecting a change in the distance between the magnetic roll in the developing device 26 and the photosensitive drum 18 that causes the density unevenness.

  In step 103, the correction control unit 46 determines whether or not the detected density unevenness can be corrected only by correcting the developing bias. If the determination is affirmative, the process proceeds to step 104, and if the determination is negative, the process proceeds to step 107.

  In step 104, the development bias correction unit 44 calculates correction information for correcting the development bias of the DC power source based on the development bias of the AC power source detected by the development bias detection unit 48, and sends it to the correction control unit 46. Set and go to step 106. That is, since the change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18 can be known from the change in the development bias of the AC power supply, the correction information of the development bias of the DC power supply that cancels the change in the distance is calculated. Then, the correction control unit 46 is set. The correction controller 46 corrects the developing bias of the DC power supply of the developing device 26 using the set correction information, so that the density resulting from the change in the distance between the magnetic roll of the developing device 26 and the photosensitive drum 18 is obtained. Unevenness is suppressed.

  On the other hand, in step 107, the development bias correction unit 44 calculates the correction information of the development bias, and the exposure amount correction unit 43 calculates the correction information of the exposure amount of the exposure device 24, and each correction information is corrected by the correction control unit. Set to 46 and go to step 106. In the present embodiment, the development bias correction unit 44 calculates correction information for correcting the development bias of the DC power source of the developing device 26 based on the development bias of the AC power source detected by the development bias detection unit 48. Set in the correction controller 46. Further, the exposure amount correction unit 43 calculates correction information for the exposure amount of the exposure device 24 and sets it in the correction control unit 46 for the amount that cannot be corrected by the developing bias. The exposure amount correction unit 43 calculates correction information for correcting the exposure amount of the exposure device 24 based on the detected development bias of the AC power supply, and the development bias correction unit 44 calculates the exposure amount correction unit 43. It is also possible to calculate development bias correction information that cannot be corrected in step (b), and to set the correction information in the correction control unit 46. In this embodiment, when the correction range of the development bias of the DC power supply is insufficient, the density unevenness in the 100% density region is corrected by correcting the development bias and exposure amount of the DC power supply. However, the present invention is not limited to this. is not. For example, when the correction range of the developing power supply bias is insufficient, at least one of the exposure amount and the charging bias voltage of the charging device 22 may be further corrected in addition to the developing bias of the DC power supply.

  In step 106, the image forming unit 16 forms a test image in a density region other than the 100% density region using the correction information set in the development bias correcting unit 44, and the process proceeds to step 108. For example, a test image of a plurality of density ranges such as a 30% density range and an 80% density range is formed.

  In step 108, the density sensor 30 detects the density of the test image, and the process proceeds to step 110. That is, by detecting the density of the test image in a density area other than the 100% density area, density unevenness in a density area other than the 100% density area is detected.

  In step 110, the correction controller 46 determines whether or not the density unevenness of the test image in each density range detected by the density sensor 30 is within a predetermined allowable range. If the determination is negative, the process proceeds to step 112. If the determination is affirmative, the density unevenness is suppressed within a predetermined allowable range by the correction in step 104 or step 107, and thus the process ends.

  In step 112, the image information correction unit 42 corrects the image information so as to suppress the density unevenness based on the detection result of the density sensor 30, and ends the series of processes. As a result, in the density areas other than the 100% density area, the density unevenness is corrected by correcting the image information.

  As described above, in the present embodiment, when correcting the density unevenness in the 100% density range, the exposure amount of the exposure device 24 is corrected more reliably even if the correction range is not sufficient only by correcting the developing bias. The density unevenness is corrected.

  In each of the above embodiments, the example in which the density unevenness in the 100% density region is detected by detecting the developing bias of the AC power supply of the developing device 26 has been described. However, the present invention is not limited to this. For example, the density unevenness may be detected by detecting the density of the test image by the density sensor 30 as in the case of detecting the density unevenness in another density range. Also, regarding the detection of density unevenness in other density areas, the density unevenness is not detected by detecting the development bias of the AC power supply of the developing device 26 as in the 100% density area, instead of detecting the density of the test image. It may be detected.

  In each of the above-described embodiments, the example has been described in which the density sensor 30 detects the density of the image transferred to the intermediate transfer belt. However, the present invention is not limited to this. For example, the density sensor 30 may be provided on the downstream side in the transport direction of the secondary transfer roll 32 in the paper transport path to detect the density of the image formed on the paper.

  In each of the above embodiments, an image forming apparatus that forms a color image has been described as an example. However, the present invention is not limited to this. For example, an image forming apparatus that forms a single color image by the single image forming unit 16 may be applied.

  Further, the processing performed by the image forming apparatus 10 according to each of the above embodiments may be processing performed by software, processing performed by hardware, or processing combining both. Further, the processing performed in the image forming apparatus 10 may be stored and distributed as a program in a storage medium.

  Further, the present invention is not limited to the above, and it is needless to say that various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 16 Image forming part 18 Photosensitive drum 22 Charging apparatus 24 Exposure apparatus 26 Developing apparatus 28 Primary transfer roll 30 Density sensor 40 Density unevenness correction part 42 Image information correction part 43 Exposure amount correction part 44 Development bias correction part 46 Correction control section 48 Development bias detection section

Claims (5)

A charging device for charging the image carrier with a charging bias;
An exposure device that exposes the charged image carrier to form a latent image represented by image information;
A developing device for developing the latent image with a developing bias to form a toner image on the image carrier;
A transfer device for transferring the toner image to a transfer medium;
A detection unit for detecting information on uneven density of the toner image formed on the transfer medium;
By correcting at least one of the charging bias, the exposure amount of the exposure apparatus, and the developing bias by using the detection result of the detection unit, the density information in the 100% density range is corrected, and then the image information is corrected. A correction unit that corrects density unevenness in a density range other than the 100% density range by correcting
An image forming apparatus including:   The image forming apparatus according to claim 1, wherein the correction unit corrects density unevenness in a 100% density region by correcting the exposure amount or the development bias.   The correction unit corrects density unevenness in a 100% density range by correcting the developing bias, and further corrects at least one of the charging bias and the exposure amount when a predetermined correction under-satisfaction condition is satisfied. Item 2. The image forming apparatus according to Item 1.   The detection unit detects density unevenness in a 100% density range by detecting a developing bias of an AC power source of the developing device, and detects density of the toner image or an image transferred to the transfer medium. 4. The image forming apparatus according to claim 1, wherein density unevenness in a density range other than the 100% density range is detected. An image forming program for causing a computer to function as a detection unit and a correction unit of the image forming apparatus according to claim 1.

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