JP2012237874A - Image forming apparatus and correction method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently correct a streak on an image.SOLUTION: There are formed an output image in an output image area 61 on a paper sheet P, and belt-shaped patterns 64 and 65 long in a main scanning direction, having a predetermined gradation, in margin areas 62 and 63 of the paper sheet P on which the output image is formed. A range in the main scanning direction of the belt-shaped patterns 64 and 65 corresponds to a range in the main scanning direction of the output image. A streak in a sub-scanning direction is detected on the basis of an output value of a belt-shaped pattern portion read by a line sensor so that image data of an image formed after the detection of the streak is corrected on the basis of a position of the detected streak, a width thereof, and a difference between the output value thereof and that of a periphery of the detected streak.

Description

  The present invention relates to an image forming apparatus and a correction method for the image forming apparatus.

  In an image forming apparatus such as a printer or a copying machine, density unevenness may occur in the image formation result. For example, in an electrophotographic image forming apparatus, compared to the surroundings on an image due to a partial transmittance difference of optical components (laser writing lens, etc.) and distortion of a charger, an exposure device, and a developing device. In some cases, a thick portion or a thin portion appears as a streak.

  As a method for detecting streaks on an image, an inspection image is separated into monochrome images of R, G, and B frames, synthesized after performing predetermined image processing on each monochrome image, and streaks from the synthesized image. A method for detecting a defect has been proposed (see Patent Document 1).

  In addition, an image forming apparatus that forms a reference image for streak detection on an intermediate transfer belt and detects the streak by reading it with an optical sensor proposes an arrangement of a plurality of rectangular patches constituting the reference image. (See Patent Document 2).

JP 11-48457 A JP 2006-215370 A

  However, it takes extra time to form an image used for streak detection on a sheet or an intermediate transfer belt separately from an output image that is an original output target. In addition, when a line correction chart is output periodically, the chart paper is wasted. In addition, if streaks begin to occur immediately after the chart is output, streaks occur in all the images that are output before the next chart is output and the streaks are corrected. There has been a problem that printing materials such as these are wasted.

  The present invention has been made in view of the above problems in the prior art, and an object thereof is to efficiently correct streaks on an image.

  In order to solve the above-mentioned problem, the invention described in claim 1 forms an output image on a sheet, and is predetermined in a margin area of the sheet on which the output image is formed, long in the main scanning direction. Based on the output value of the band-shaped pattern portion read by the line sensor, an image forming unit that forms a band-shaped pattern with different gradations, a line sensor that reads an image formed on the paper, and Formed by the image forming unit after detecting the streak and detecting the streak based on the detected value of the streak in the main scanning direction and the output value difference between the detected streak and the periphery of the detected streak And a streak correction processing unit that performs streak correction for correcting image data of an image.

  According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the blank area of the paper is a portion that is cut after an image is formed on the paper.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, a range in the main scanning direction of the belt-like pattern coincides with a range in the main scanning direction of the output image, or the output Larger than the range of the image for scanning in the main scanning direction, the streak correction processing unit detects the position of the end of the band-shaped pattern in the main scanning direction from the image read by the line sensor, and the detected band-shaped pattern The position of the muscle is specified based on the distance in the main scanning direction from the end of the muscle to the muscle.

  According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the image forming unit forms a registration mark along with the belt-like pattern on the paper, and the belt-like pattern in the main scanning direction. The end portion coincides with the position of the registration mark in the main scanning direction, or has a predetermined distance from the registration mark in the main scanning direction, and the streak correction processing unit reads the image from the image read by the line sensor. The position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction are detected, the distance in the main scanning direction from the end of the detected strip pattern to the streak is specified, and the specified Based on the distance and the relationship between the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction. Identifying the correct position relative to the serial output image.

  According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, the image forming unit forms a plurality of belt-like patterns with a plurality of different gradations.

  According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects, the image forming unit forms an image with a plurality of output colors, and the image forming unit Forms the strip pattern with all output colors of the plurality of output colors.

  According to a seventh aspect of the present invention, in the image forming apparatus according to the sixth aspect, the plurality of output colors are yellow, magenta, cyan, and black.

  According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the image forming unit separately forms a belt-like pattern made of yellow, magenta, and cyan and a belt-like pattern made only of black. To do.

  According to a ninth aspect of the present invention, in the image forming apparatus according to the seventh or eighth aspect, the line sensor includes a line sensor of each color channel of red, green, and blue, and the stripe correction processing unit includes the red color Cyan lines are detected based on the output value of the band-shaped pattern portion read by the line sensor of the channel, and magenta lines are detected based on the output value of the band-shaped pattern portion read by the line sensor of the green channel. And detecting a yellow streak based on the output value of the band-shaped pattern portion read by the blue channel line sensor, and reading by the line sensor of at least one of the red, green, and blue color channels. Black streaks are detected based on the output value of the band-shaped pattern portion.

  According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first to ninth aspects, the streak correction processing unit performs correction according to the paper type for each paper type of the paper. Do.

  According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, when the image forming unit performs image formation continuously, the paper type of the paper on which the paper type of the paper is imaged immediately before is formed. When it is the same kind as the seed, the formation of the belt-like pattern is omitted.

  According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the streak correction processing unit has a predetermined output value difference from the periphery of the detected streaks. If the value is greater than or equal to the specified value, image formation by the image forming unit is stopped.

  According to a thirteenth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the streak correction processing unit detects a streak in the sub-scanning direction again after performing the streak correction. Then, when the output value difference from the periphery of the re-detected muscle is greater than a predetermined value, the strength of the muscle correction is changed.

  The invention according to claim 14 is the image forming apparatus according to any one of claims 1 to 11, further comprising a plurality of paper discharge trays, wherein the stripe correction processing unit performs the stripe correction, When a streak in the sub-scanning direction is detected again, and the output value difference from the periphery of the re-detected streak is greater than or equal to a predetermined value, it is determined that the output value difference is greater than or equal to a predetermined value. The paper on which the image is formed is output to a paper discharge tray different from a normal paper discharge tray among the plurality of paper discharge trays.

  According to a fifteenth aspect of the present invention, in the image forming apparatus according to any one of the first to eleventh aspects, the image forming apparatus includes a display unit and an operation unit, and the line correction processing unit performs the line correction. After that, when the streak in the sub-scanning direction is detected again and the difference in output value from the periphery of the re-detected streak is equal to or greater than a predetermined value, the image formation by the image forming unit is temporarily stopped and repaired. When the display unit displays an indication to prompt the user and an operation instruction indicating that the repair is completed is received from the operation unit, the output value difference is determined to be greater than or equal to a predetermined value. The image forming unit is again formed.

  According to the sixteenth aspect of the present invention, an output image is formed on a sheet, and a strip-like pattern having a predetermined gradation long in the main scanning direction is formed in a margin area of the sheet on which the output image is formed. A streak in the sub-scanning direction is detected based on an image forming process to be performed, an image reading process for reading an image formed on the sheet by a line sensor, and an output value of the band-shaped pattern portion read by the line sensor. Image data of an image formed after the detected muscle is detected based on the difference in output values between the detected muscle and the position and width of the detected muscle in the main scanning direction and the periphery of the detected muscle. And a streak correction step for performing streak correction for correcting the image.

  According to a seventeenth aspect of the present invention, in the correction method of the image forming apparatus according to the sixteenth aspect, the blank area of the paper is a portion that is cut after an image is formed on the paper.

  According to an eighteenth aspect of the present invention, in the correction method for an image forming apparatus according to the sixteenth or seventeenth aspect, a range in the main scanning direction of the belt-like pattern coincides with a range in the main scanning direction of the output image. Alternatively, it is larger than the range of the output image in the main scanning direction, and in the streak detection step, the position of the end of the strip pattern in the main scanning direction is detected from the image read by the line sensor, and is detected. The position of the stripe is specified based on the distance in the main scanning direction from the end of the belt-like pattern to the stripe.

  According to a nineteenth aspect of the present invention, in the correction method for an image forming apparatus according to the sixteenth or seventeenth aspect, in the image forming step, a registration mark is formed on the paper together with the belt-like pattern, and the main part of the belt-like pattern is formed. An end in the scanning direction coincides with a position of the registration mark in the main scanning direction, or has a predetermined distance from the registration mark in the main scanning direction. In the streak detection step, an image read by the line sensor Detecting the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction, identifying the distance in the main scanning direction from the end of the detected strip pattern to the streak, Based on the identified distance and the relationship between the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction, Identifying the correct position relative to the output image from 査 direction position.

  According to a twentieth aspect of the present invention, in the image forming apparatus correction method according to any one of the sixteenth to nineteenth aspects, in the image forming step, a plurality of belt-like patterns are formed with a plurality of different gradations.

  According to a twenty-first aspect of the present invention, in the correction method for an image forming apparatus according to any one of the sixteenth to twentieth aspects, the image forming step forms an image with a plurality of output colors. In the image forming step, the belt-like pattern is formed with all output colors of the plurality of output colors.

  According to a twenty-second aspect of the present invention, in the correction method for an image forming apparatus according to the twenty-first aspect, the plurality of output colors are yellow, magenta, cyan, and black.

  According to a twenty-third aspect of the present invention, in the correction method for an image forming apparatus according to the twenty-second aspect, in the image forming step, a band-shaped pattern made of yellow, magenta and cyan is separated from a band-shaped pattern made only of black. To form.

  According to a twenty-fourth aspect of the present invention, in the correction method for an image forming apparatus according to the twenty-second or twenty-third aspect, the line sensor includes line sensors of red, green, and blue color channels. Cyan lines are detected based on the output values of the band-shaped pattern portion read by the line sensor of the red channel, and magenta lines are detected based on the output values of the band-shaped pattern portion read by the line sensor of the green channel. And detecting yellow streaks based on the output value of the band-shaped pattern portion read by the blue channel line sensor, and reading by at least one color channel line sensor of red, green, and blue. Further, the black streak is detected based on the output value of the band-shaped pattern portion.

  According to a twenty-fifth aspect of the present invention, in the correction method for an image forming apparatus according to any one of the sixteenth to twenty-fourth aspects, in the streak correcting step, the paper type of the paper is determined according to the paper type. Make corrections.

  According to a twenty-sixth aspect of the present invention, in the correction method for an image forming apparatus according to the twenty-fifth aspect, in the image forming step, an image is formed immediately before the paper type of the paper when performing continuous image formation. When the paper type is the same as the paper type, the formation of the belt-like pattern is omitted.

  According to a twenty-seventh aspect of the present invention, in the correction method for an image forming apparatus according to any one of the sixteenth to twenty-sixth aspects, an output value difference with respect to the detected streaks is not less than a predetermined value. A stop determination step of stopping image formation in the image forming step.

  According to a twenty-eighth aspect of the present invention, in the correction method for an image forming apparatus according to any one of the sixteenth to twenty-sixth aspects, after performing the streak correction, a streak in the sub-scanning direction is detected again, and the re-scanning is performed again. A step of changing the strength of the muscle correction when the output value difference from the detected muscle periphery is equal to or greater than a predetermined value;

  According to a twenty-ninth aspect of the present invention, in the correction method for an image forming apparatus according to any one of the sixteenth to twenty-sixth aspects, the image forming apparatus includes a plurality of discharge trays and performs the streak correction. After that, when the streak in the sub-scanning direction is detected again and the output value difference from the periphery of the re-detected streak is equal to or greater than a predetermined value, the output value difference is equal to or greater than a predetermined value. A step of outputting the paper on which the judged image is formed to a paper discharge tray different from a normal paper discharge tray among the plurality of paper discharge trays.

  The invention according to claim 30 is the image forming apparatus correction method according to any one of claims 16 to 26, wherein the image forming apparatus includes a display unit and an operation unit, and the line correction is performed. Then, the streak in the sub-scanning direction is detected again, and when the difference in output value from the periphery of the re-detected streak is equal to or larger than a predetermined value, the image formation in the image forming process is temporarily stopped. When the display unit is prompted to repair and an operation instruction indicating that the repair is completed is received from the operation unit, the output value difference is determined to be greater than or equal to a predetermined value. A step of re-forming the image.

  According to the present invention, compared to a case where only a belt-like pattern is formed on a sheet different from the output image, it is possible to reduce wasted sheets and shorten the time required for correction. Therefore, the streaks on the image can be corrected efficiently.

1 is a schematic configuration diagram of an image forming apparatus. 2 is a block diagram illustrating a functional configuration of the image forming apparatus. FIG. It is an example of stripe correction data. It is a figure which shows the example of a strip | belt-shaped pattern. It is a figure which shows the relationship between the installation direction of a line sensor, and the direction of a line | wire. It is a flowchart which shows an image formation process. It is a flowchart which shows a strip | belt-shaped pattern addition process. It is a flowchart which shows a muscle detection process. It is a figure for demonstrating the detection method of a muscle generation | occurrence | production location. It is a flowchart which shows a line | wire correction process. It is a figure which shows the example of the corrected amount along a main scanning direction. It is a figure which shows the example of the correction | amendment shape of a main scanning direction. It is a figure which shows the other example of a strip | belt-shaped pattern. It is a flowchart which shows the stop determination process in 2nd Embodiment. It is a figure which shows the example of the strip | belt-shaped pattern in 3rd Embodiment. It is a flowchart which shows the muscle position specific process in 3rd Embodiment. It is a flowchart which shows the strip | belt-shaped pattern addition process A in 4th Embodiment. It is a flowchart which shows the 1st line | wire correction effect judgment processing in 5th Embodiment. It is a flowchart which shows the 2nd line | wire correction effect judgment process in 6th Embodiment. It is a flowchart which shows the 3rd stripe correction effect judgment processing in 7th Embodiment.

[First Embodiment]
First, a first embodiment of an image forming apparatus according to the present invention will be described.
FIG. 1 is a schematic configuration diagram of the image forming apparatus 100. As shown in FIG. 1, the image forming apparatus 100 includes an image reading unit 20, an image forming unit 30, a paper feeding unit 40, a line sensor 50, and the like.

  The image reading unit 20 includes a document feeding unit 21 that automatically feeds a document and a scanner unit 22. The document feeder 21 transports the document placed on the document table by the transport mechanism and feeds it toward the scanner unit 22. The scanner unit 22 optically scans the original, photoelectrically converts the original by the line image sensor CCD 23, reads the original image, and generates red (R), green (G), and blue (B) image data.

  The image forming unit 30 includes image forming units 8Y, 8M, 8C, and 8K for each color, an intermediate transfer belt 5, a fixing device 9 for fixing a toner image by heating and pressing, a paper transport unit, and the like. The image forming units 8Y, 8M, 8C, and 8K for the respective colors are arranged along the sub-scanning direction in the order of colors for transferring the toner images onto the intermediate transfer belt 5.

  The image forming unit 8Y that forms a yellow (Y) image includes a photoconductor drum 1Y, a charging unit 2Y, an exposure unit 3Y, a developing unit 4Y, and a photoconductor cleaning unit 7Y. The charging unit 2Y uniformly charges the photosensitive drum 1Y. The exposure unit 3Y exposes the charged photosensitive drum 1Y based on the image data (Y data) to form an electrostatic latent image. The developing unit 4Y attaches yellow toner to the photosensitive drum 1Y to form a yellow toner image. The photoreceptor cleaning unit 7Y removes the residual toner on the photoreceptor drum 1Y after the yellow toner image is transferred from the photoreceptor drum 1Y onto the intermediate transfer belt 5.

  The image forming unit 8M that forms a magenta (M) image includes a photosensitive drum 1M, a charging unit 2M, an exposure unit 3M, a developing unit 4M, and a photosensitive member cleaning unit 7M. The charging unit 2M uniformly charges the photosensitive drum 1M. The exposure unit 3M exposes the charged photosensitive drum 1M based on image data (M data) to form an electrostatic latent image. The developing unit 4M adheres magenta toner to the photosensitive drum 1M to form a magenta toner image. The photoconductor cleaning unit 7M removes residual toner on the photoconductor drum 1M after the magenta toner image is transferred from the photoconductor drum 1M to the intermediate transfer belt 5.

  The image forming unit 8C that forms a cyan (C) image includes a photosensitive drum 1C, a charging unit 2C, an exposure unit 3C, a developing unit 4C, and a photosensitive member cleaning unit 7C. The charging unit 2C uniformly charges the photosensitive drum 1C. The exposure unit 3C exposes the charged photosensitive drum 1C based on image data (C data) to form an electrostatic latent image. The developing unit 4C attaches cyan toner to the photosensitive drum 1C to form a cyan toner image. The photoreceptor cleaning unit 7C removes the residual toner on the photoreceptor drum 1C after the cyan toner image is transferred from the photoreceptor drum 1C onto the intermediate transfer belt 5.

  The image forming unit 8K that forms a black (K) image includes a photosensitive drum 1K, a charging unit 2K, an exposure unit 3K, a developing unit 4K, and a photosensitive member cleaning unit 7K. The charging unit 2K uniformly charges the photosensitive drum 1K. The exposure unit 3K exposes the charged photosensitive drum 1K based on the image data (K data) to form an electrostatic latent image. The developing unit 4K attaches black toner to the photosensitive drum 1K to form a black toner image. The photoreceptor cleaning unit 7K removes residual toner on the photoreceptor drum 1K after the black toner image is transferred from the photoreceptor drum 1K onto the intermediate transfer belt 5.

  In the developing units 4Y, 4M, 4C, and 4K, development is performed by reversal development in which a developing bias in which an AC voltage is superimposed on a DC voltage having the same polarity as the toner polarity to be used is applied.

  To the intermediate transfer belt 5, the toner images of the respective colors formed on the photosensitive drums 1Y, 1M, 1C, and 1K are transferred to form color toner images. Each color toner image formed on the photosensitive drums 1Y, 1M, 1C, and 1K is rotated by primary transfer rollers 6Y, 6M, 6C, and 6K to which a primary transfer bias having a polarity opposite to that of the toner to be used is applied. The toner images are sequentially transferred onto the intermediate transfer belt 5 to form a color toner image in which the respective colors are superimposed (primary transfer).

  The paper feed unit 40 is provided with a plurality of paper feed trays 41, 42, and 43. Each of the paper feed trays 41, 42, and 43 stores sheets of a predetermined paper type and size. The paper feed unit 40 conveys the paper fed from the paper feed trays 41, 42, 43 to the image forming unit 30. The paper stored in the paper feed trays 41, 42, and 43 is conveyed to the secondary transfer roller 31 through a conveyance roller, a registration roller, and the like. Then, the color toner images are collectively transferred from the intermediate transfer belt 5 onto the sheet by the secondary transfer roller 31 (secondary transfer). After the color toner image is transferred onto the paper by the secondary transfer roller 31, the residual toner is removed by the intermediate transfer belt cleaning unit 32 from the intermediate transfer belt 5 that has separated the curvature of the paper.

  The sheet on which the color toner image has been transferred is fixed by the fixing device 9 and is sandwiched between the discharge rollers and placed on a discharge tray outside the apparatus.

  The line sensor 50 is provided at the subsequent stage of the fixing device 9. The line sensor 50 has a width equal to or larger than the maximum width of the paper used in the image forming apparatus 100 in a direction (main scanning direction) orthogonal to the paper transport direction, and reads an image formed on the paper. In the line sensor 50, a plurality of reading elements are arranged in a line in a direction orthogonal to the paper conveyance direction, and each reading element outputs an output value corresponding to reflected light reflected from an image on the paper. .

  The line sensor 50 includes red, green, and blue color channel line sensors arranged in parallel. The line sensor of the red channel includes a red filter and outputs an output value (R signal) corresponding to the light intensity. The green channel line sensor includes a green filter and outputs an output value (G signal) corresponding to the light intensity. The blue channel line sensor includes a blue filter and outputs an output value (B signal) corresponding to the intensity of light.

  FIG. 2 is a block diagram illustrating a functional configuration of the image forming apparatus 100. As shown in FIG. 2, the image forming apparatus 100 includes a control unit 10, an operation unit 11, a display unit 12, a communication unit 13, a storage unit 14, an image reading unit 20, an image forming unit 30, a paper feeding unit 40, a line sensor. 50 or the like. Of the functional units shown in FIG. 2, portions described with reference to FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

  The control unit 10 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU reads various processing programs stored in the storage unit 14 and develops them in the RAM, and comprehensively controls the processing operations of each unit of the image forming apparatus 100 in cooperation with the programs.

  The operation unit 11 is a functional unit that accepts an operation by the user, has various buttons such as a numeric button, a start button, and a reset button, and outputs a pressed signal of the pressed button to the control unit 10. The operation unit 11 includes a touch panel formed integrally with the display unit 12. The operation unit 11 detects a position on the touch panel that is touched by a user's fingertip, a touch pen, or the like, and sends a position signal to the control unit 10. Output.

  The display unit 12 is configured by an LCD (Liquid Crystal Display) or the like, and displays various operation screens, processing results, and the like according to instructions of a display signal input from the control unit 10.

  The communication unit 13 is an interface for transmitting and receiving data to and from an external device such as a PC (Personal Computer).

The storage unit 14 is a storage device such as a nonvolatile memory or a hard disk, and stores various processing programs and various data.
As shown in FIG. 3, the storage unit 14 stores the line correction data acquired for each paper type, each output color (YMCK), and each gradation. The muscle correction data includes a muscle start position, a muscle width, and a muscle generation level for each muscle generation location.

The storage unit 14 stores “setting for adding a belt-like pattern to the output image” and “setting for correcting streaks” so as to be able to be switched on / off. The trays 41, 42, and 43 are stored in association with the paper types and sizes stored in the respective paper feed trays.

  The control unit 10 performs image processing on the image data generated by the image reading unit 20 or the image data received by the communication unit 13 to generate image data for writing, and the exposure units 3Y and 3M of the image forming unit 30. , 3C, 3K is supplied with image data (YMCK data).

  The control unit 10 serving as a streak correction processing unit forms an image when the “setting for adding a belt-like pattern to the output image” stored in the storage unit 14 is ON and the sheet is larger than the output image. The unit 30 is controlled to form an output image on the paper, and to form a strip-like pattern having a predetermined gradation long in the main scanning direction in a margin area of the paper on which the output image is formed. The “paper margin area” is a portion that is cut after an image is formed on the paper. Further, the “predetermined gradation” is preferably a gradation that is easy to detect streaks, and a halftone is used.

FIG. 4 shows an example of a strip pattern. The paper P includes an output image area 61 and margin areas 62 and 63. The output image area 61 is an area where an output image (a part used as a printed material) is formed. Registration marks T1 to T4 are formed at the four corners of the output image area 61. After the image is formed, the sheet is cut according to the registration marks T1 to T4.
In the example of FIG. 4, belt-like patterns 64 and 65 are formed in the blank area 62 with different gradations. Each of the belt-like patterns 64 and 65 is uniformly configured with the same gradation on the image data. In addition, the range in the main scanning direction of the belt-like patterns 64 and 65 coincides with the range in the main scanning direction of the output image. That is, the positions of both end portions of the strip patterns 64 and 65 in the main scanning direction coincide with the positions of the register marks T1 to T4 in the main scanning direction.

  In the first embodiment, the image forming unit 30 alternately forms the belt-like patterns 64 and 65 (process black) made of yellow, magenta, and cyan, and the belt-like pattern 64 made only of black, one by one for the paper P. , 65 are formed. That is, the belt-like patterns 64 and 65 made of yellow, magenta, and cyan and the belt-like patterns 64 and 65 made only of black are separately formed on different papers P. The belt-like patterns 64 and 65 made of yellow, magenta, and cyan are grays having different gradations in a state where yellow, magenta, and cyan are mixed.

  The control unit 10 detects a streak in the sub-scanning direction based on the output value of the band-shaped pattern portion read by the line sensor 50. The control unit 10 detects the position of the end of the strip pattern in the main scanning direction from the image read by the line sensor 50, and based on the distance in the main scanning direction from the end of the detected strip pattern to the streak. The position of the muscle is specified.

  FIG. 5 shows the relationship between the installation direction of the line sensor 50 and the direction of the line. In FIG. 5, streaks 66, 67, 68 are generated at three locations. The muscles 66 and 67 are muscles having a higher density than the surroundings, and the muscle 68 is a muscle having a lower density than the surroundings.

  The control unit 10 detects cyan, magenta, and yellow streaks based on the output value of the band-shaped pattern portion made of yellow, magenta, and cyan read by the line sensor 50. Specifically, the control unit 10 detects cyan streaks based on the output value of the strip pattern portion read by the red channel line sensor, and outputs the strip pattern portion read value by the green channel line sensor. The magenta streak is detected based on the above, and the yellow streak is detected based on the output value of the belt-like pattern portion read by the blue channel line sensor.

  The control unit 10 detects black streaks on the basis of the output value of the band-shaped pattern portion composed only of black read by the line sensor 50. Specifically, the control unit 10 detects black stripes based on the output value of the band-shaped pattern portion read by the line sensor of at least one color channel of red, green, and blue. For black streak detection, the output value of the band-shaped pattern portion read by the line sensor of one of the color channels of red, green, and blue may be used, or two or more of red, green, and blue may be used. A value obtained by adding or averaging the output values of the belt-like pattern portions read by the line sensors of the color channels may be used.

  When the “setting for correcting streak” stored in the storage unit 14 is ON, the control unit 10 outputs the position and width of the detected streak in the main scanning direction, and the detected streak surroundings. Based on the value difference, the image data of the image formed by the image forming unit 30 after the streak is detected is corrected. Specifically, the control unit 10 corrects the portion corresponding to the position of the streak of the image data so that the output value difference from the periphery of the detected streak is reduced at the position where the streak is detected.

Next, the operation will be described.
FIG. 6 is a flowchart showing an image forming process executed in the image forming apparatus 100. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.

  First, the control unit 10 performs PIP (Raster Image Processor) processing on PDL (Page Description Language) data received from a PC or the like via the communication unit 13 to generate image data of an output image. (Step S1). Specifically, the control unit 10 interprets the PDL data and converts it into bitmap image data (YMCK data).

  Next, the control unit 10 performs color tone / gradation adjustment on the image data of the output image generated by the PIP process (step S2). The color tone / gradation adjustment is a function for adjusting the color tone / gradation specified by the user or the user's favorite color tone / gradation.

  Next, the control unit 10 performs character correction processing on the image data of the output image that has been subjected to color tone / gradation adjustment (step S3). The character correction process includes a process of thinning a character by image processing when a character is thickened, a process of emphasizing a character edge to make the character easy to see, and the like. In addition, when it is not necessary to perform a character correction process, it does not need to perform.

  Next, the line correction process is performed on the image data of the output image on which the character correction process has been performed by the control unit 10 (step S4). Since the muscle correction process is a process performed based on the muscle correction data acquired before that, details of the muscle correction process will be described later (see FIG. 10).

  Next, the output gradation correction is performed on the image data of the output image by the control unit 10 (step S5). The output gradation correction is a function for correcting to a predetermined gradation for the purpose of improving the output stability of the image forming unit 30.

Next, a belt-like pattern addition process is performed by the control unit 10 on the image data of the output image on which the output tone correction has been performed (step S6).
Here, with reference to FIG. 7, the band-shaped pattern addition processing will be described.

  The control unit 10 determines whether or not “setting for adding a belt-like pattern to the output image” stored in the storage unit 14 is ON (step S11). If the “setting for adding a belt-like pattern to the output image” is ON (step S11; YES), the control unit 10 determines whether the output paper is nobi paper (paper that is slightly larger than the output image). Is determined (step S12). Specifically, the size of the output image and the size of the output paper are compared by the control unit 10, and whether or not the output paper is larger than the output image, that is, whether or not there is a blank area on the output paper. Is judged. Note that the size of the output sheet is included in the setting information received together with the PDL data.

  When the output paper is nobi paper (step S12; YES), the control unit 10 acquires the width in the main scanning direction of the output image from the information obtained by the RIP process in step S1 (step S13). .

  Next, the control unit 10 generates a band-shaped pattern according to the width of the output image, and the generated band-shaped pattern is added to the area corresponding to the margin area of the output paper with respect to the image data of the output image. (Step S14). That is, the range of the strip pattern in the main scanning direction matches the range of the output image in the main scanning direction. Note that a band-shaped pattern composed of yellow, magenta, and cyan and a band-shaped pattern composed of only black are alternately added to the image data of the output image in the output order. Also, as shown in FIG. 4, it is desirable to add a plurality of belt-like patterns with a plurality of different gradations.

  Next, registration marks are added to the four corners of the output image by the control unit 10 with respect to the image data of the output image to which the belt-like pattern is added (step S15).

  In step S11, if “setting for adding a band pattern to the output image” is not ON (step S11; NO), or if the output sheet is not a nobi sheet in step S12 (step S12; NO), the band A pattern is not added (step S16).

  After step S15 or step S16, returning to FIG. 6, the control unit 10 performs screen processing on the image data of the output image (step S7). Screen processing is processing for expressing gradation (density) using a plurality of screens.

  Next, the control unit 10 performs PWM (Pulse Width Modulation) conversion on the image data of the output image subjected to the screen processing in accordance with the gradation value (step S8).

Next, the image forming unit 30 forms an image on the sheet in accordance with the PWM signal based on the gradation value (step S9). When a belt-like pattern and a registration mark are added to the output image, the image forming unit 30 forms an output image on the paper and also forms a belt-like pattern and a registration mark.
This completes the image forming process.

  FIG. 8 is a flowchart showing a streak detection process executed in the image forming apparatus 100. This process is performed for each paper type, each output color, and each gradation, and is realized by software processing in cooperation with the CPU of the control unit 10 and the program stored in the storage unit 14.

First, the line sensor 50 acquires an image on a sheet on which a belt-like pattern is formed (step S21).
When detecting the cyan streak, the output value of the band-shaped pattern portion composed of yellow, magenta, and cyan read by the line sensor of the red channel is used. When detecting the magenta streak, the output value of the band-shaped pattern portion made of yellow, magenta, and cyan read by the line sensor of the green channel is used. When the yellow stripe is detected, the output value of the belt-like pattern portion made of yellow, magenta, and cyan read by the blue channel line sensor is used.

  When black stripes are detected, an output value of a band-shaped pattern portion composed of only black read by a line sensor of at least one color channel of red, green, and blue is used. Specifically, black streaks may be detected using the output value of the band-shaped pattern portion read by the line sensor of one of the color channels of red, green and blue, or red, green and blue Alternatively, the black streaks may be detected using a value obtained by adding or averaging the output values of the band-shaped pattern portions read by the line sensors of two or more color channels.

  Next, the position of the end of the strip pattern in the main scanning direction is detected from the image read by the line sensor 50 by the control unit 10 (step S22). For example, the control unit 10 detects the boundary between the belt-shaped pattern portion and another portion (the portion outside the belt-shaped pattern and where no image is formed) as an edge in the main scanning direction, so that the belt-shaped pattern is detected. Is detected.

Next, the control unit 10 averages the portion corresponding to the belt-like pattern in the output value of the line sensor 50 in the sub-scanning direction (step S23). That is, the output value of the line sensor 50 read from the belt-like pattern area is averaged in the sub-scanning direction for each position in the main scanning direction, and a profile in the main scanning direction is generated. On the image, since the streaks continue in the sub-scanning direction, the average value of the output values of the line sensor 50 read from the belt-shaped pattern region in the sub-scanning direction can also be obtained. Features appear. FIG. 9 shows an example of a profile in the main scanning direction.
Next, the average value D of the output values in the main scanning direction is acquired from the profile in the main scanning direction by the control unit 10 (step S24).

Next, a value obtained by adding the predetermined value E to the average value D of the profile is obtained by the control unit 10 as the first threshold value F1, and a value obtained by subtracting the predetermined value E from the average value D of the profile is the first value. 2 is obtained as a threshold value F2 (step S25). Here, the predetermined value E is predetermined for each paper type, each output color, and each gradation of the belt-like pattern, and is stored in the storage unit 14.
First threshold value F1 = (average value D of profile) + predetermined value E
2nd threshold value F2 = (average value D of profile) −predetermined value E

  Next, in the profile in the main scanning direction, the control unit 10 sets pixels that are equal to or higher than the first threshold value F1 or pixels that are equal to or lower than the second threshold value F2 as streak candidates (step S26).

  Next, the control unit 10 counts the number of pixels in which the muscle candidates are continuous, and specifies a portion where the number of continuous pixels of the muscle candidates is a predetermined value H1 or more and a predetermined value H2 (H2> H1) or less as a muscle occurrence location. (Step S27). That is, a portion where the number of continuous pixels of the muscle candidate is less than the predetermined value H1 or larger than the predetermined value H2 is excluded from the muscle occurrence location. In this way, streaks in the sub-scanning direction are detected.

Next, the control unit 10 calculates the average value of the streaks in the profile in the main scanning direction for each streaks, and calculates the difference between the average value of the streaks and the average value D of the profile ( Output value difference) is obtained as the muscle generation level (step S28).
Muscle generation level = (average value of muscle generation location) − (average value D of profile)
Here, the difference between the average value of the streaks and the average value D of the profile is set as the streak level, but the difference between the output value and the average value D of the profile may be set as the streak level for each pixel. .

  Next, the streak start position, the streak width, and the streak generation level in the main scanning direction are obtained by the control unit 10 as the streak correction data for each corresponding paper type, output color, and gradation in the storage unit 14. Stored (step S29). As shown in FIG. 9, the muscle start position is determined by the control unit 10 from the end of the detected band-like pattern to the muscle start position (in the profile in the main scanning direction, the output value is greater than or equal to the first threshold value F1 or the second threshold value). Is determined on the basis of the distance in the main scanning direction to a position starting to become less than or equal to the threshold value F2. The streak position is specified by the streak start position and the streak width in the main scanning direction (in the main scanning direction profile, the number of continuous pixels whose output value is greater than or equal to the first threshold F1 or less than or equal to the second threshold F2). After the streak detection, the image data of the image formed by the image forming unit 30 is corrected based on the streak start position, the streak width, and the streak generation level in the next image formation on the same paper type.

Next, the line correction process (step S4 in FIG. 6) will be described with reference to FIG.
The control unit 10 determines whether or not “setting for correcting streaks” stored in the storage unit 14 is ON (step S31). When “setting to correct streaks” is ON (step S31; YES), the control unit 10 refers to the storage unit 14 to determine whether or not there is streak correction data for the paper type of the output paper. (Step S32). Note that the paper type of the output paper is included in the setting information received together with the PDL data.

  If there is line correction data for the paper type of the output paper (step S32; YES), the control unit 10 corrects the image for output and the image data of the belt-like pattern based on the line correction data for the paper type. (Step S33). Specifically, the muscle start level, the muscle width, and the muscle generation level acquired by the control unit 10 for each output color (YMCK) and for each gradation are referred to, and the muscle generation level corresponding to the muscle width from the muscle start position. The image data is corrected so as to reduce the streaks with a correction amount according to the above. For example, the correction amount is added to the image data (YMCK data) output to the image forming unit 30. When the line correction data is acquired for a plurality of gradations, the correction amount calculated based on the line generation level acquired in the gradation higher than the correction target gradation and lower than the correction target gradation The correction amount calculated based on the muscle generation level acquired in the gradation is linearly interpolated to calculate the correction amount for the gradation to be corrected.

It should be noted that the correction amount may be continuously and gently changed at the boundary portion of the muscle generation location. FIG. 11 shows an example of the correction amount along the main scanning direction. A correction amount corresponding to the stripe width and the stripe generation level is obtained for the correction start positions POS0, POS1, and POS2 with reference to the reference position (the end portion of the belt-like pattern in the main scanning direction) for each stripe generation location.
FIG. 12 shows an example of a correction shape in the main scanning direction. The “correction start position” from the reference position is determined by the “muscle start position” of the muscle correction data stored in the storage unit 14. The “correction amount maximum value” is determined based on the “muscle generation level” of the muscle correction data stored in the storage unit 14. “Slope” is a predetermined fixed value, and in the inclined portion of FIG. 12, the correction amount changes by 1 as the slope pixel proceeds in the main scanning direction. “Correction maximum value width” is a value obtained by subtracting “(slope × maximum correction amount value) × 2” from “muscle width” of the muscle correction data stored in the storage unit 14.

In step S31, if “setting for correcting streaks” is not ON (step S31; NO), or if there is no streak correction data for the paper type of the output paper in step S32 (step S32; NO), streaks. Correction is not performed (step S34).
This completes the line correction processing.

  As described above, according to the first embodiment, since the belt-like pattern is formed in the blank area of the paper on which the output image is formed, only the belt-like pattern is formed on a paper different from the image for output. Compared to the case, it is possible to reduce the number of sheets that are wasted, and it is possible to reduce the time required for correction. Therefore, the streaks on the image can be corrected efficiently.

In addition, the blank area can be used effectively by forming a strip-like pattern for streak detection in the blank area of the paper cut after image formation.
In addition, since a band-like pattern is formed on the same paper as the output image, it is possible to detect streaks at an early stage when streaks start to occur, and to reduce defective output products (output products with streaks). Can be made.

Further, by making the range in the main scanning direction of the belt-like pattern coincide with the range in the main scanning direction of the output image, the use of a printing material such as toner can be minimized.
Further, by specifying the position of the stripe based on the relative position from the end of the belt-like pattern, the position accuracy of the line correction can be improved without being influenced by the positional deviation of the paper when the line sensor 50 reads the image. Can do.

In addition, by forming a belt-like pattern with all the output colors among a plurality of output colors, it is possible to perform line correction for each output color.
Further, by forming the band-shaped pattern made of yellow, magenta, and cyan and the band-shaped pattern made only of black, the streaks of the respective output colors can be detected with high accuracy.
Further, by forming a gray belt-like pattern in which yellow, magenta, and cyan are mixed, it is possible to correct the streaks of yellow, magenta, and cyan using the same belt-like pattern.

In the first embodiment, a case has been described in which a belt-like pattern made of yellow, magenta, and cyan and a belt-like pattern made only of black are alternately formed on the paper one by one. It is good also as forming a strip | belt-shaped pattern in order one sheet for every. For example, a yellow band pattern is formed in the first blank area, a magenta band pattern is formed in the second blank area, and a cyan band pattern is formed in the third blank area. A black belt-like pattern is formed in the fourth blank region, a yellow belt-like pattern is formed in the fifth blank region, and so on.
In this case, the control unit 10 detects cyan stripes based on the output value of the cyan belt-shaped pattern portion read by the red channel line sensor, and detects the magenta belt-shaped pattern portion read by the green channel line sensor. Based on the output value, magenta streaks are detected, and on the basis of the output value of the yellow strip pattern portion read by the blue channel line sensor, yellow streaks are detected, and at least one of red, green, and blue The black streak is detected based on the output value of the black belt-like pattern portion read by the channel line sensor.
By forming a belt-like pattern for each output color, noise at the time of reading by the line sensor 50 is reduced, and the accuracy of line detection can be improved.

  Further, as shown in FIG. 13, with respect to the paper P including the output image area 71 and the margin areas 72 and 73, the margin area 72 has strip patterns 74 and 75 made of yellow, magenta, and cyan, and the margin area 73. The belt-like patterns 76 and 77 made of only black may be formed separately. For the strip patterns 74 and 75 (process black) composed of yellow, magenta, and cyan, output color components of cyan, magenta, and yellow are respectively obtained from the same image by the line sensors for the red, green, and blue channels. Can be read, and the streak correction of each output color can be performed.

  In the first embodiment, the image forming process (see FIG. 6) has been described by way of an example based on the image data received by the communication unit 13, but the image data generated by the image reading unit 20 is also described. It may be based on. In this case, for the paper type and size of the output paper, the paper type and size associated with the paper feed trays 41, 42, and 43 selected from the operation unit 11 are read from the storage unit 14. Further, the width of the output image in the main scanning direction is acquired from the image data generated by the image reading unit 20.

In the first embodiment, the case where the range in the main scanning direction of the belt-like pattern coincides with the range in the main scanning direction of the output image has been described. However, the range of the belt-like pattern in the main scanning direction is used for output. It may be larger than the range of the image in the main scanning direction.
Also in this case, the position of the end of the strip pattern in the main scanning direction is detected from the image read by the line sensor 50, and based on the distance in the main scanning direction from the end of the detected strip pattern to the streak. The position of the muscle may be specified. The correction position for the output image is specified based on the specified streak position and the relationship between the main scanning direction range of the belt-like pattern and the main scanning direction range of the output image.

[Second Embodiment]
Next, a second embodiment to which the present invention is applied will be described.
The image forming apparatus according to the second embodiment has the same configuration as that of the image forming apparatus 100 according to the first embodiment. Therefore, FIG. 1 and FIG. 2 are used, and the configuration is illustrated and described. Omitted. Further, the belt-like pattern formed on the paper may be the belt-like pattern shown in FIGS. 4 and 13 or the belt-like pattern shown in FIG. 15 described later in the third embodiment. Hereinafter, a configuration and processing characteristic of the second embodiment will be described.

  The control unit 10 stops the image formation by the image forming unit 30 when the difference between the detected output values from the periphery of the muscle is equal to or larger than a predetermined value.

  FIG. 14 is a flowchart illustrating a stop determination process executed in the image forming apparatus according to the second embodiment. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.

  The result of the streak detection process (see FIG. 8) for the paper type of the output paper is read from the storage unit 14 by the control unit 10, and the streak generation level is greater than or equal to a predetermined value J1 (J1> 0) or a predetermined value J2 (J2 <J 0) It is determined whether or not there are the following streaks (step S41). That is, it is determined whether or not the difference between the output values around the streaks is equal to or greater than a predetermined value (the absolute value of the predetermined value J1 or the absolute value of the predetermined value J2).

  When there is no streak generation portion whose streak generation level is equal to or higher than the predetermined value J1 or lower than the predetermined value J2 for the paper type of the output paper (step S41; NO), the control unit 10 performs image formation as it is by the image forming unit 30. The process continues (step S42).

  On the other hand, when there is a streak generation portion whose streak generation level is equal to or higher than the predetermined value J1 or lower than the predetermined value J2 for the paper type of the output paper (step S41; YES), the control unit 10 causes the image forming unit 30 to form an image. Is stopped (step S43).

  As described above, according to the second embodiment, when the degree of streaks generated on an image is large, image formation is stopped, so that it is not necessary to increase the number of defective output items unnecessarily.

[Third Embodiment]
Next, a third embodiment to which the present invention is applied will be described.
Since the image forming apparatus in the third embodiment has the same configuration as the image forming apparatus 100 shown in the first embodiment, FIG. 1 and FIG. 2 are used, and the configuration is illustrated and described. Omitted. Hereinafter, a configuration and processing characteristic of the third embodiment will be described.

  FIG. 15 shows an example of a belt-like pattern formed on a sheet by the image forming apparatus according to the third embodiment. Band-shaped patterns 84 and 85 are formed in the margin area 82 for the paper P including the output image area 81 and the margin areas 82 and 83. Also, register marks T11 to T14 are formed at the four corners of the output image area 81. After the image is formed, the paper is cut according to the register marks T11 to T14. The end portions of the strip patterns 84 and 85 in the main scanning direction are configured to be outside by a predetermined distance X from the end portions of the output image in the main scanning direction (positions of the registration marks T11 to T14). . FIG. 15 shows an example in which the end of the strip pattern in the main scanning direction and the position of the registration marks T11 to T14 in the main scanning direction have an interval of the distance X. The positions of the end portion and the registration mark in the main scanning direction may be the same.

  The image forming unit 30 alternately forms band-like patterns 84 and 85 (process black) made of yellow, magenta, and cyan and band-like patterns 84 and 85 made of only black on the paper P one by one. That is, the belt-like patterns 84 and 85 made of yellow, magenta, and cyan and the belt-like patterns 84 and 85 made only of black are separately formed on different papers P.

  The control unit 10 detects the positions of the end portions of the strip patterns 84 and 85 in the main scanning direction and the positions of the registration marks T11 to T14 in the main scanning direction from the image read by the line sensor 50, and detects the detected strip patterns. The distance in the main scanning direction from the ends of 84 and 85 to the streak is specified. The relationship between the specified distance and the positions of the end portions of the strip patterns 84 and 85 in the main scanning direction and the positions of the registration marks T11 to T14 in the main scanning direction (the band patterns 84 and 85 in the main scanning direction). Based on the distance X) between the end portions and the registration marks T11 to T14, the correction position for the output image from the positions of the registration marks T11 to T14 is specified.

  FIG. 16 is a flowchart showing a line position specifying process executed in the image forming apparatus according to the third embodiment. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.

  First, the line sensor 50 acquires an image on a sheet on which a belt-like pattern and a registration mark are formed (step S51).

  Next, the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction are detected from the image read by the line sensor 50 by the control unit 10 (step S52). The distance in the main scanning direction from the end of the pattern to the line is specified (step S53).

Next, the position of the registration mark in the main scanning direction is determined based on the distance determined by the control unit 10 and the relationship between the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction. The correction position for the output image from is specified (step S54).
This completes the muscle position specifying process.

  As described above, according to the third embodiment, the position accuracy of the line correction can be improved by specifying the line position based on the relative position from the position of the registration mark.

[Fourth Embodiment]
Next, a fourth embodiment to which the present invention is applied will be described.
The image forming apparatus according to the fourth embodiment has the same configuration as that of the image forming apparatus 100 according to the first embodiment. Therefore, FIG. 1 and FIG. 2 are used, and the configuration is illustrated and described. Omitted. Hereinafter, a configuration and processing characteristic of the fourth embodiment will be described.

  When the image forming unit 30 performs image formation continuously, the control unit 10 omits the formation of the belt-like pattern when the paper type of the paper is the same as the paper type of the paper on which the image is formed immediately before. .

  In the fourth embodiment, a strip pattern addition process A shown in FIG. 17 is performed instead of the strip pattern addition process shown in FIG. Other processes are the same as those in the first embodiment. However, as the belt-like pattern formed on the paper, a pattern including all output color components (yellow, magenta, cyan, black) on the same paper as shown in FIG. 13 is used.

  The processes in steps S61 and S62 in FIG. 17 are the same as the processes in steps S11 and S12 in FIG.

  Next, the control unit 10 determines whether image formation is being performed continuously by the image forming unit 30, that is, whether or not continuous sheet passing is in progress (step S63). When continuous paper is being passed (step S63; YES), the paper type of the paper on which the image is formed in the image forming unit 30 by the control unit 10 is the same as the paper type of the paper on which the image was formed immediately before. Is determined (step S64). In the case of image formation based on the image data received by the communication unit 13, the output paper type is included in the setting information received together with the PDL data, and the image generated by the image reading unit 20 is used. In the case of image formation based on data, the paper type associated with the paper feed trays 41, 42, 43 selected from the operation unit 11 is read from the storage unit 14.

  When the paper type of the paper on which the image is formed in the image forming unit 30 is not the same as the paper type of the paper on which the image is formed immediately before (step S64; NO), or when the continuous paper is not being passed in step S63 (Step S63; NO), the process proceeds to Step S65. The processes in steps S65 to S67 in FIG. 17 are the same as the processes in steps S13 to S15 in FIG.

In step S61, when “setting for adding a belt-like pattern to the output image” is not ON (step S61; NO), in step S62, when the output paper is not noble paper (step S62; NO), or in step S64. If the paper type of the paper on which the image is formed is the same as the paper type of the paper on which the image was formed immediately before (step S64; YES), no belt-like pattern is added (step S68). That is, the formation of the strip pattern is omitted.
Thus, the band-shaped pattern addition process A ends.

  As described above, according to the fourth embodiment, when image formation is continuously performed by the image forming unit 30, the paper type of the paper is the same as the paper type of the paper on which the image was formed immediately before. In this case, since the formation of the belt-like pattern is omitted, the line correction can be performed efficiently.

[Fifth Embodiment]
Next, a fifth embodiment to which the present invention is applied will be described.
The image forming apparatus in the fifth embodiment has the same configuration as the image forming apparatus 100 shown in the first embodiment. Therefore, FIG. 1 and FIG. 2 are used, and the configuration is illustrated and described. Omitted. Hereinafter, a configuration and processing characteristic of the fifth embodiment will be described.

  The control unit 10 performs the line correction on the band-shaped pattern based on the line correction data, and then detects the line in the sub-scanning direction again based on the output value of the band-shaped pattern portion read by the line sensor 50, When the difference between the output values of the re-detected muscle and its surroundings is equal to or larger than a predetermined value, the strength of the muscle correction is changed. Specifically, the control unit 10 increases the strength of the muscle correction when the effect of the muscle correction is small even after the muscle correction is performed.

  FIG. 18 is a flowchart illustrating a first stripe correction effect determination process executed in the image forming apparatus according to the fifth embodiment. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.

  First, the control unit 10 detects the streak in the sub-scanning direction from the image read by the line sensor 50, similarly to the streak detection process shown in FIG. 8 (step S71).

  Next, the control unit 10 performs line correction on the output image and the band-like pattern based on the line correction data, similarly to the line correction process shown in FIG. A band-shaped pattern is formed (step S72). Then, the control unit 10 detects the streak in the sub-scanning direction again based on the output value of the band-shaped pattern portion read by the line sensor 50 (step S73). As the muscle correction data, the muscle start position, the muscle width, and the muscle occurrence level are calculated for each muscle occurrence location.

  Here, the control unit 10 determines whether or not the absolute value of the muscle generation level is equal to or greater than the predetermined value Q, that is, whether or not the output value difference from the detected muscle periphery is equal to or greater than a predetermined value. (Step S74). When the absolute value of the muscle generation level is equal to or greater than the predetermined value Q (step S74; YES), the strength of the muscle correction is changed by the control unit 10 (step S75). Specifically, based on the muscle generation level, a correction amount for reducing the muscle is calculated and added to the current value. And it returns to step S72 and a process is repeated.

  On the other hand, if the absolute value of the muscle generation level is less than the predetermined value Q in step S74 (step S74; NO), it is determined that the correction effect is sufficient, and the first muscle correction effect determination process ends.

  As described above, according to the fifth embodiment, when the effect of the muscle correction is small, the strength of the muscle correction is changed, so that the muscle correction according to the degree of the occurrence of the muscle can be performed.

[Sixth Embodiment]
Next, a sixth embodiment to which the present invention is applied will be described.
The image forming apparatus according to the sixth embodiment has the same configuration as that of the image forming apparatus 100 described in the first embodiment. Therefore, FIGS. 1 and 2 are used, and the configuration is illustrated and described. Omitted. Hereinafter, a configuration and processing characteristic of the sixth embodiment will be described.

The image forming apparatus according to the sixth embodiment includes a plurality of paper discharge trays.
The control unit 10 performs the line correction on the band-shaped pattern based on the line correction data, and then detects the line in the sub-scanning direction again based on the output value of the band-shaped pattern portion read by the line sensor 50, When the output value difference from the periphery of the re-detected streaks is greater than or equal to a predetermined value, a plurality of sheets on which an image for which the output value difference is determined to be greater than or equal to a predetermined value are formed Output to a different paper discharge tray from the normal paper discharge tray. That is, even after performing the line correction, when the effect of the line correction is small, the control unit 10 leaves a line in the output image formed on the sheet. As described above, the paper is discharged to a tray different from the tray from which the normal paper is discharged.

FIG. 19 is a flowchart illustrating a second stripe correction effect determination process executed in the image forming apparatus according to the sixth embodiment. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.
The processes in steps S81 to S84 in FIG. 19 are the same as the processes in steps S71 to S74 in FIG.

  In step S84, if the absolute value of the muscle generation level is greater than or equal to the predetermined value Q (step S84; YES), that is, if the output value difference from the detected muscle periphery is greater than or equal to a predetermined value, The sheet on which the image on which the absolute value of the streak generation level has been determined by the control unit 10 is determined to be equal to or greater than the predetermined value Q is output to a discharge tray different from the normal discharge tray (step S85).

  On the other hand, in step S84, when the absolute value of the muscle generation level is less than the predetermined value Q (step S84; NO), it is determined that the correction effect is sufficient, and the control unit 10 determines the absolute value of the muscle generation level. The paper on which the image determined to be less than the predetermined value Q is output is output to a normal paper discharge tray (step S86).

  As described above, according to the sixth embodiment, when the effect of streak correction is small, a sheet on which a streak-generated image is formed is ejected from a different ejection tray from a normal ejection tray. Therefore, a defective output product can be discharged separately from a normal output product.

[Seventh Embodiment]
Next, a seventh embodiment to which the present invention is applied will be described.
Since the image forming apparatus in the seventh embodiment has the same configuration as the image forming apparatus 100 shown in the first embodiment, FIG. 1 and FIG. 2 are used, and the configuration is illustrated and described. Omitted. Hereinafter, a configuration and processing characteristic of the seventh embodiment will be described.

The control unit 10 performs the line correction on the band-shaped pattern based on the line correction data, and then detects the line in the sub-scanning direction again based on the output value of the band-shaped pattern portion read by the line sensor 50, When the output value difference from the periphery of the re-detected muscle is equal to or larger than a predetermined value, the image forming unit 30 temporarily stops the image formation and causes the display unit 12 to display that the repair is urged. Repairs include cleaning optical lenses and mirrors, replacing rollers that cause streaks, and the like.
Thereafter, when receiving an operation instruction indicating that the repair is completed from the operation unit 11, the control unit 10 causes the image forming unit 30 to form an image for which it is determined that the output value difference is equal to or greater than a predetermined value. Let it be done again.

FIG. 20 is a flowchart illustrating a third stripe correction effect determination process executed in the image forming apparatus according to the seventh embodiment. This processing is realized by software processing by cooperation between the CPU of the control unit 10 and the program stored in the storage unit 14.
The processes in steps S91 to S94 in FIG. 20 are the same as the processes in steps S71 to S74 in FIG.

  In step S94, if the absolute value of the muscle generation level is greater than or equal to the predetermined value Q (step S94; YES), that is, if the output value difference from the detected muscle periphery is greater than or equal to a predetermined value, The control unit 10 temporarily stops image formation by the image forming unit 30 (step S95), and a display for prompting repair is displayed on the display unit 12 (step S96). The image forming apparatus according to the seventh embodiment includes means such as an optical lens, a mirror, and a roller for identifying the cause of the generation of the streak. In step S96, the part that causes the streak is cleaned. Or exchange.

  Next, when there is an operation instruction indicating that the repair is completed from the operation unit 11 (step S97; YES), the control unit 10 controls the image forming unit 30, and the absolute value of the streak generation level is a predetermined value Q. The formation of the image determined as above is performed again (step S98).

  After step S98 or when the absolute value of the muscle generation level is less than the predetermined value Q in step S94 (step S94; NO), the process ends.

  As described above, according to the seventh embodiment, when the effect of the line correction is small, the image formation by the image forming unit 30 is temporarily stopped and the display prompting the repair is performed. The cause can be notified to the user. In addition, after the repair is completed, it is possible to redo the image formation in which the streaks have occurred.

The description in each of the above embodiments is an example of the image forming apparatus according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of each part constituting the apparatus can be changed as appropriate without departing from the spirit of the present invention.
For example, the processes that are characteristic in the above embodiments may be performed in combination.

  In each of the above embodiments, the electrophotographic image forming apparatus has been described. However, other types of image forming apparatuses such as an ink jet printer may be used.

  In the above description, an example in which a non-volatile memory or a hard disk is used as a computer-readable medium storing a program for executing each process is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave may be applied as a medium for providing program data via a communication line.

DESCRIPTION OF SYMBOLS 10 Control part 11 Operation part 12 Display part 13 Communication part 14 Storage part 20 Image reading part 30 Image forming part 40 Paper feed part 50 Line sensor 61 Output image area 62, 63 Margin area 64, 65 Strip pattern 71 Output image area 72, 73 Margin areas 74, 75, 76, 77 Strip pattern 81 Output image areas 82, 83 Blank areas 84, 85 Strip pattern 100 Image forming apparatus

Claims (30)

An image forming unit that forms an output image on a sheet and forms a belt-like pattern having a predetermined gradation long in a main scanning direction in a blank area of the sheet on which the output image is formed;
A line sensor for reading an image formed on the paper;
Based on the output value of the strip-shaped pattern portion read by the line sensor, a streak in the sub-scanning direction is detected, and the position and width of the detected streak in the main scanning direction and the periphery of the detected streak are detected. A line correction processing unit that performs line correction for correcting image data of an image formed by the image forming unit after the line is detected based on the output value difference;
An image forming apparatus comprising: The margin area of the paper is a portion to be cut after an image is formed on the paper.
The image forming apparatus according to claim 1. The range of the strip pattern in the main scanning direction coincides with the range of the output image in the main scanning direction, or is larger than the range of the output image in the main scanning direction,
The streak correction processing unit detects the position of the end of the strip-shaped pattern in the main scanning direction from the image read by the line sensor, and the distance in the main scanning direction from the end of the strip-shaped pattern to the streak Based on the location of the muscle,
The image forming apparatus according to claim 1. The image forming unit forms a registration mark along with the belt-like pattern on the paper,
The end of the strip pattern in the main scanning direction coincides with the position of the registration mark in the main scanning direction, or has a predetermined interval in the main scanning direction from the registration mark.
The streak correction processing unit detects the position of the end of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction from the image read by the line sensor, and detects the end of the detected strip pattern The distance in the main scanning direction from the portion to the line is specified, and based on the specified distance and the relationship between the position of the end portion of the strip pattern in the main scanning direction and the position of the registration mark in the main scanning direction Identifying a correction position for the output image from a position in the main scanning direction of the registration mark;
The image forming apparatus according to claim 1. The image forming unit forms a plurality of belt-like patterns with a plurality of different gradations;
The image forming apparatus according to claim 1. The image forming unit forms an image with a plurality of output colors,
The image forming unit forms the strip pattern in all output colors of the plurality of output colors;
The image forming apparatus according to claim 1. The plurality of output colors are yellow, magenta, cyan, and black.
The image forming apparatus according to claim 6. The image forming unit separately forms a belt-like pattern made of yellow, magenta, and cyan and a belt-like pattern made only of black.
The image forming apparatus according to claim 7. The line sensor is composed of line sensors of red, green and blue color channels,
The stripe correction processing unit detects cyan stripes based on an output value of the strip-shaped pattern portion read by the red channel line sensor, and outputs the strip-shaped pattern portion read by the green channel line sensor. A magenta streak is detected based on the value, a yellow streak is detected based on the output value of the strip-shaped pattern portion read by the blue channel line sensor, and at least one of the red, green, and blue colors Detecting black streaks based on the output value of the band-shaped pattern portion read by the line sensor of the channel;
The image forming apparatus according to claim 7 or 8. The line correction processing unit performs correction according to the paper type for each paper type of the paper.
The image forming apparatus according to claim 1. The image forming unit omits the formation of the belt-like pattern when performing continuous image formation and the paper type of the paper is the same as the paper type of the paper on which image formation was performed immediately before,
The image forming apparatus according to claim 10. The line correction processing unit stops image formation by the image forming unit when an output value difference from the detected line surroundings is equal to or greater than a predetermined value;
The image forming apparatus according to claim 1. The line correction processing unit detects the line in the sub-scanning direction again after performing the line correction, and when the output value difference from the periphery of the line detected again is equal to or greater than a predetermined value, Change the strength of the line correction,
The image forming apparatus according to claim 1. With multiple output trays,
The line correction processing unit detects the line in the sub-scanning direction again after performing the line correction, and when the output value difference from the periphery of the line detected again is equal to or greater than a predetermined value, Outputting a sheet on which an image determined to have an output value difference equal to or greater than a predetermined value to a discharge tray different from a normal discharge tray among the plurality of discharge trays;
The image forming apparatus according to claim 1. A display unit;
An operation unit;
With
The line correction processing unit detects the line in the sub-scanning direction again after performing the line correction, and when the output value difference from the periphery of the line detected again is equal to or greater than a predetermined value, The output value difference is determined in advance when image display by the image forming unit is temporarily stopped, the display unit is prompted to repair, and an operation instruction indicating that the repair is completed is received from the operation unit. Causing the image forming unit to form an image that has been determined to be greater than or equal to the given value,
The image forming apparatus according to claim 1. An image forming step of forming an output image on a sheet and forming a belt-like pattern having a predetermined gradation long in a main scanning direction in a blank area of the sheet on which the output image is formed;
An image reading step of reading an image formed on the paper by a line sensor;
A streak detecting step of detecting streaks in the sub-scanning direction based on the output value of the strip-shaped pattern portion read by the line sensor;
Based on the output value difference between the detected position and width of the streak in the main scanning direction and the periphery of the detected streak, streak correction is performed to correct image data of an image formed after the streak is detected. A line correction process to be performed;
A correction method for an image forming apparatus including: The margin area of the paper is a portion to be cut after an image is formed on the paper.
The method for correcting an image forming apparatus according to claim 16. The range of the strip pattern in the main scanning direction coincides with the range of the output image in the main scanning direction, or is larger than the range of the output image in the main scanning direction,
In the streak detection step, the position of the end of the strip-shaped pattern in the main scanning direction is detected from the image read by the line sensor, and the distance in the main scanning direction from the end of the strip-shaped pattern to the streak is detected. Based on the location of the muscle,
18. A method for correcting an image forming apparatus according to claim 16 or 17. In the image forming step, a registration mark is formed on the paper together with the belt-like pattern,
The end of the strip pattern in the main scanning direction coincides with the position of the registration mark in the main scanning direction, or has a predetermined interval in the main scanning direction from the registration mark.
In the streak detection step, the position of the end of the strip-shaped pattern in the main scanning direction and the position of the registration mark in the main scanning direction are detected from the image read by the line sensor, and the end of the detected strip-shaped pattern The distance in the main scanning direction from the line to the line is specified, and based on the specified distance, and the relationship between the position of the end of the belt-like pattern in the main scanning direction and the position of the registration mark in the main scanning direction, Specify a correction position for the output image from a position in the main scanning direction of the registration mark.
18. A method for correcting an image forming apparatus according to claim 16 or 17. In the image forming step, a plurality of strip patterns are formed with a plurality of different gradations.
The correction method of the image forming apparatus as described in any one of Claims 16-19. The image forming step is to form an image with a plurality of output colors,
In the image forming step, the belt-like pattern is formed with all output colors among the plurality of output colors.
21. The correction method for an image forming apparatus according to claim 16. The plurality of output colors are yellow, magenta, cyan, and black.
The method for correcting an image forming apparatus according to claim 21. In the image forming step, a band-shaped pattern composed of yellow, magenta, and cyan and a band-shaped pattern composed of only black are separately formed.
23. A correction method for an image forming apparatus according to claim 22. The line sensor is composed of line sensors of red, green and blue color channels,
In the stripe detection step, cyan stripes are detected based on the output value of the strip pattern portion read by the red channel line sensor, and the output value of the strip pattern portion read by the green channel line sensor is detected. The magenta streak is detected based on the color channel, the yellow streak is detected based on the output value of the strip-shaped pattern portion read by the blue channel line sensor, and at least one of the red, green, and blue color channels is detected. Detecting black streaks based on the output value of the band-shaped pattern portion read by the line sensor;
The correction method for an image forming apparatus according to claim 22 or 23. In the line correction step, for each paper type of the paper, correction according to the paper type is performed.
The method for correcting an image forming apparatus according to any one of claims 16 to 24. In the image forming step, when the image formation is continuously performed, if the paper type of the paper is the same as the paper type of the paper on which the image is formed immediately before, the formation of the belt-like pattern is omitted.
26. A correction method for an image forming apparatus according to claim 25. Including a stop determination step of stopping image formation in the image forming step when the difference between the output values of the detected muscle and the surroundings is a predetermined value or more.
27. A correction method for an image forming apparatus according to any one of claims 16 to 26. After performing the streak correction, the streak in the sub-scanning direction is detected again, and the strength of the streak correction is changed when the output value difference from the periphery of the re-detected streak is equal to or greater than a predetermined value. Including steps,
27. A correction method for an image forming apparatus according to any one of claims 16 to 26. The image forming apparatus includes a plurality of paper discharge trays,
After performing the line correction, the line in the sub-scanning direction is detected again, and the output value difference is determined in advance when the output value difference from the periphery of the line detected again is greater than or equal to a predetermined value. Including a step of outputting a sheet on which an image determined to be equal to or greater than the value is output to a discharge tray different from a normal discharge tray among the plurality of discharge trays.
27. A correction method for an image forming apparatus according to any one of claims 16 to 26. The image forming apparatus includes a display unit and an operation unit,
After performing the streak correction, the streak in the sub-scanning direction is detected again, and when the output value difference from the periphery of the re-detected streak is equal to or greater than a predetermined value, image formation in the image forming step is performed. The output value difference is equal to or greater than a predetermined value when the display unit displays a message that prompts repair and prompts repair, and an operation instruction that repair is completed is received from the operation unit. Including the step of causing the determined image to be formed again.
27. A correction method for an image forming apparatus according to any one of claims 16 to 26.