JP2005003830A - Image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming device capable of improving user convenience by performing a color image formation while maintaining readability and image quality as much as possible without shutting down the device even when compensation of a color deviation is impossible. <P>SOLUTION: A digital color copying machine carries out procedures in consideration of user convenience, such as enabling color printing by carrying out image processing in the edge region of the image data created by an image creating means in which a color deviation impossible to be compensated is caused, when the color deviation proves to be impossible to be compensated for some reason or another as a result of detection of the color deviation by a resist pattern. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus that forms a color image by superimposing a plurality of images.
[0002]
[Prior art]
In recent years, in the field of color image forming apparatuses, a plurality of image forming units are provided for the purpose of increasing the image forming speed, and each image forming unit forms an image of a different color on an image carrier such as a photosensitive drum. However, so-called tandem color image forming apparatuses that form a color image by sequentially transferring and superimposing them onto a recording sheet conveyed by a recording sheet conveyance body such as a transfer belt have been increasing. In a color image forming apparatus employing this method, the transfer position of each image is shifted due to an attachment error of the image carrier or uneven rotation speed when transferring / superimposing each color image formed by each image forming unit. As a result, color misregistration may occur.
[0003]
In order to prevent such color misregistration, each image forming unit forms a resist pattern with a predetermined shape on the recording sheet conveyance body, detects these with a sensor or the like, and calculates the amount of misregistration between the resist patterns. Then, so-called registration correction is performed to correct the image transfer position by each image forming unit based on the amount of positional deviation.
[0004]
In addition, if the detection data of the resist pattern includes false detections due to scratches on the recording sheet conveyance body, registration correction is prohibited, and after warning is given, image formation is prohibited by stopping the device. Alternatively, there has been proposed an image forming apparatus that permits only image formation in a single color or permits image formation only when the user is aware (see, for example, Patent Document 1).
[0005]
[Patent Document 1]
JP 2002-351183 A
[0006]
[Problems to be solved by the invention]
However, in the image forming apparatus described in Patent Document 1, when the detection is detected in the resist pattern detection data and the apparatus is stopped, monochrome image formation without color misregistration is also possible. If the image cannot be formed and only monochrome image formation is permitted, the color image cannot be formed, which is inconvenient for the user. Also, if the user is aware that image formation is permitted without performing registration correction, problems remain in terms of image quality and readability.
[0007]
An object of the present invention is to solve such problems, and even when color misregistration cannot be corrected, image processing in full color while maintaining readability and image quality as much as possible by performing image processing without stopping the apparatus. An object of the present invention is to provide an image forming apparatus and an image forming method capable of improving user-friendliness by forming.
[0008]
[Means for Solving the Problems]
As specific means for achieving the above object, the present invention according to claim 1 includes a plurality of image forming means for forming images based on image data of different colors, and each image forming means is used for image formation. In the image forming apparatus capable of forming a color image by multiplex-transferring each color image onto a transfer means or transfer material, a detection means for detecting a color shift of the color image caused by a shift of any transfer position of the image forming means And an abnormality determining means for determining whether or not the color misregistration can be corrected based on a detection result by the detecting means, an area determining means for determining an edge region in the image data, and the color misregistration cannot be corrected by the abnormality determining means. The edge region of the image data formed by the image forming means in which color misregistration that cannot be corrected is generated, and the image data of the extended edge region is further expanded. Characterized by comprising an image processing means for dividing.
[0009]
The present invention according to claim 2 includes a plurality of image forming means for forming an image based on image data of different colors, and the images of the respective colors formed by the respective image forming means are transferred to the transfer means or the transfer material in a multiple transfer manner. In the image forming apparatus capable of forming a color image, a detection unit that detects a color shift of the color image caused by a shift of any transfer position of the image forming unit, and a color shift based on a detection result by the detection unit Abnormality determination means for determining whether or not the image can be corrected, area determination means for determining an edge area in the image data, black character determination means for determining whether the document image is a color document including black characters, and abnormality determination means If it is determined that the color misregistration cannot be corrected by the black character determination unit and the original image is determined to be a color original including black characters, the black character Extend the edge region of the image data of the color, further characterized in that an image processing means for replacing the image data of the expanded edge regions of the image data of black.
[0010]
According to a third aspect of the present invention, there are provided a plurality of image forming means for forming images based on image data of different colors, and the images of the respective colors formed by the respective image forming means are transferred onto the transfer means or transfer material in a multiple transfer manner. In the image forming method of the image forming apparatus capable of forming a color image, a detection step for detecting a color shift of the color image caused by a shift of any transfer position of the image forming means, and a detection result by the detection step If it is determined that the color misregistration cannot be corrected by the abnormality determination step for determining whether or not the color misregistration can be corrected, an area determination step for determining an edge region in the image data, and the abnormality determination step, Extends the edge area of the image data created by the image creation means in which color misregistration that cannot be corrected occurs, and deletes the image data of the extended edge area. And having a image processing steps.
[0011]
According to a fourth aspect of the present invention, there are provided a plurality of image forming means for forming images based on image data of different colors, and images of each color formed by the respective image forming means are transferred to a transfer means or a transfer material in a multiple transfer manner. In the image forming method of the image forming apparatus capable of forming a color image, a detection step for detecting a color shift of the color image caused by a shift of any transfer position of the image forming means, and a detection result by the detection step An abnormality determination step for determining whether or not the color misregistration can be corrected based on an area determination step for determining an edge region in the image data, and a black character determination step for determining whether the document image is a color document including black characters. In the case where it is determined that the color misregistration cannot be corrected by the abnormality determination step, the color of the original image including black characters is determined by the black character determination step If it is determined that the draft, extend the edge region of the image data of each color in the black character, further characterized in that a step of replacing the image data of the expanded edge regions of the image data of black.
[0012]
[Action]
According to the image forming apparatus and the image forming method according to claim 1 and 3, when the color misregistration cannot be corrected, an image is formed in the edge region of the image data created by the image forming unit in which the color misregistration has occurred. Processing is performed.
[0013]
According to the image forming apparatus and the image forming method described in claims 2 and 4, when the color misregistration cannot be corrected and the document image is a color document including black characters, the edge region of the black characters is displayed. Image processing is performed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the accompanying drawings.
[0015]
<First Embodiment>
FIG. 1 is a schematic configuration diagram of a digital color copying machine 1 which is an image forming apparatus according to a first embodiment of the present invention. The digital color copying machine 1 has an image reader unit 100 that reads a document image and an image printer unit 101 that reproduces image data read by the image reader unit 100.
[0016]
The image reader unit 100 includes an original glass 12 on which the original 11 is placed, an exposure lamp 13 that irradiates the original 11, a first mirror 14, a second mirror 15, a third mirror 16, and a reflected light that folds reflected light from the original 11. And a CCD sensor 18 that converts the collected light into an electric signal, an image processing conversion unit 19 that performs various processes on the converted electric signal, and the like.
[0017]
By irradiating the document 11 with the exposure lamp 13 while moving the first slider composed of the exposure lamp 13 and the first mirror 14 and the second slider composed of the second mirror 15 and the third mirror 16 in the direction of the arrow in the figure, The document reflected light incident on the CCD sensor 18 is converted into red, green, and blue electrical signals by the CCD sensor 18 (hereinafter, red, green, and blue are represented as R, G, and B, respectively), and the image processing conversion unit 19. In FIG. 5, the analog signal is converted into image data composed of RGB 8-bit digital signals by A / D conversion.
[0018]
The image printer unit 101 includes an image control unit 20, an exposure scanning unit 30, an image processing unit 40, a paper feeding unit 50, and a fixing unit 60, and forms an image by a known electrophotographic method.
[0019]
The image control unit 20 performs known image processing such as shading correction, line-to-line correction, and variable magnification movement processing on the RGB image data output from the image processing conversion unit 19, and then cyan, magenta, and yellow Are converted into image data of each reproduction color of black (hereinafter, the reproduction colors of cyan, magenta, yellow, and black are represented as C, M, Y, and K, respectively, and this C is assigned to the component number related to each reproduction color. , M, Y, and K are added as subscripts). The image data is temporarily stored in an image memory (not shown) in the image control unit 20 for each of C, M, Y, and K reproduction colors, and then synchronized with the supply of a recording sheet as a transfer material. It is read out for each scanning line and simultaneously becomes a drive signal for the LED arrays 42C to 42K.
[0020]
The exposure scanning unit 30 deflects light emitted from LED arrays 42 </ b> C to 42 </ b> K, which will be described later, by the polygon mirror 31 based on the drive signal output from the image control unit 20, ff lens (not shown), and reflection. The light is guided to the photosensitive drums 43C to 43K through the mirror groups 32C to 32K.
[0021]
The image processing unit 40 includes a recording sheet conveyance unit 44 in which a transfer belt 45 as a transfer unit is stretched around a driving roller 46 and a driven roller 47, and an upstream side in the recording sheet conveyance direction (hereinafter referred to as a transfer sheet 45). Image forming unit 41C for each color of C, M, Y, and K, which is image forming means arranged at a predetermined interval along the conveyance direction downstream side (hereinafter simply referred to as “downstream side”) from the “upstream side”) ~ 41K. The image forming units 41C to 41K are known ones including photoconductor drums 43C to 43K, LED arrays 42C to 42K for exposing and scanning the surface, a charging charger, a developing device, a transfer charger, and a cleaner. The image forming units 41C to 41K are main portions of an image forming unit 41K that forms an image with black toner and an image forming unit 41C to 41Y that forms an image with CMY color toner so that maintenance can be easily performed. Are unitized and configured to be detachable from the main body of the digital color copying machine 1 in units. The paper feeding unit 50 includes paper feeding cassettes 51, 52, and 53 for storing recording sheets of different sizes, and pickup rollers 54, 55, and 56 for feeding out the recording sheets from the respective paper feeding cassettes. It includes a registration roller 57 and the like for taking a timing to send the recording sheet to the transfer belt 45.
[0022]
Before the photosensitive drums 43C to 43K are exposed by the LED arrays 42C to 42K, the residual toner on the surface is removed by a cleaner, and thereafter, the photosensitive drums 43C to 43K are uniformly charged by a charging charger. Thus, the photosensitive drums 43C to 43K are exposed in a uniformly charged state, and an electrostatic latent image is formed on the surface thereof. Each electrostatic latent image is developed by a developing device of each color, whereby C, M, Y, and K toner images are formed on the surfaces of the photosensitive drums 43C to 43K. The toner images of the respective colors are sequentially transferred onto the recording sheet conveyed by the transfer belt 45 by the electrostatic action of the transfer charger disposed on the back side of the transfer belt 45 at each transfer position. At this time, the image forming operation of the image forming unit for each color is executed while shifting the timing from the upstream side toward the downstream side so that the toner image is superimposed and transferred at the same position on the recording sheet being conveyed. Is done.
[0023]
The recording sheet onto which the toner images of each color are transferred in multiples is conveyed to the fixing unit 60 by the transfer belt 45 and is pressed under high heat by a fixing roller 61 having a heater therein, so that the toner particles are fused on the surface of the recording sheet. After being attached and fixed, the paper is discharged to the paper discharge tray 70.
[0024]
FIG. 2 shows a block diagram of the image control unit 20 and its surroundings in FIG. However, only the registration correction related unit 21 which is an element related to registration correction in the image control unit 20 is shown (the entire configuration of the image control unit 20 will be described later with reference to FIG. 7). The resist correction related unit 21 generates a pattern data including data relating to a resist pattern shape, a gradation (density) value, a formation position in the main scanning direction, and a formation timing (formation position in the sub-scanning direction) described later. A data generation unit 212, an engine control unit 211 that controls each unit of the image printer unit 101 to form a resist pattern in accordance with the pattern data, and a correction amount using the deviation amount data measured by the pattern detection unit 48 serving as detection means. The calculated color misregistration correction calculation unit 213 includes a calculation abnormality determination unit 214 that is an abnormality determination unit that determines whether or not the amount of deviation can be corrected and sets a calculation abnormality flag when correction is not possible. Each of these components is functionally realized by processing executed according to a predetermined computer program by the CPU 23 (see FIG. 7) constituting the image control unit 20. Each of these components may be realized by a dedicated hard logic circuit.
[0025]
Next, registration correction executed by the registration correction related unit 21 will be described with reference to the flowchart shown in FIG. The digital color copying machine 1 performs registration correction at various timings such as when the power is turned on, when an opening / closing door (not shown) is opened / closed, or when a printing command is not issued for a long time. When a command to perform registration correction is issued from the image control unit 20, first, the pattern data generation unit 212 generates pattern data including data relating to the shape and formation position of the resist pattern (step S1). Next, the engine control unit 211 controls each unit of the image printer unit 101 to form a resist pattern corresponding to the pattern data in the recording sheet conveyance unit 44 that is a recording sheet conveyance region in the transfer belt 45. The formed resist pattern is detected by a pattern detection unit 48 such as a sensor, and the deviation amounts of C, M, and Y with respect to K are measured based on the detection result (step S2).
[0026]
Various known methods can be adopted as the method for measuring the resist pattern and the amount of deviation. For example, in order to measure the color misregistration amount in the sub-scanning direction, as shown in FIG. 4, a linear shape extending in parallel to a direction (main scanning direction) orthogonal to the transfer belt 45 conveyance direction as shown in FIG. The resist patterns are formed in the order of K, C, M, and Y with an interval of 1 mm in the transport direction (sub-scanning direction). The formed resist pattern is detected by the pattern detection unit 48 as the transfer belt 45 rotates. A clock with a predetermined frequency is counted by an oscillator (not shown), and the distance between the resist patterns is specified by the number of clocks (time) when each color resist pattern is detected. For example, if the distance between the K resist pattern and the M resist pattern is determined to be 2.03 mm in distance units, the K and M resist patterns are supposed to be formed at a timing of 2 mm. The deviation amount is 2 (mm) −2.03 (mm) = − 0.03 (mm). The digital color copying machine 1 according to the present embodiment measures C, M, and Y deviation amounts with respect to K with reference to K. For example, the deviation amounts of Y, K, and C with respect to M are measured with reference to M. The amount of deviation may be measured using any other color as a reference.
[0027]
Returning to FIG. 3, next, the color misregistration correction calculation unit 213 calculates a correction amount using the measured misregistration amount data (step S3). At that time, the calculation abnormality determination unit 214 determines whether or not the deviation amount can be corrected (step S4). That is, the measured deviation amount is compared with a preset threshold value R in order to determine whether or not the deviation amount is within a correctable range.
[0028]
When the amount of deviation is smaller than the threshold value R, that is, when the amount of deviation is within the correctable range (YES in step S4), a required image forming unit 41C based on the correction amount calculated by the color misregistration correction calculating unit 213. The image formation timing of .about.41Y is corrected (step S5).
[0029]
On the other hand, when the deviation amount is larger than the threshold value R, that is, when the deviation amount exceeds the correctable range (NO in step S4), the calculation abnormality determination unit 214 sets the calculation abnormality flag for each of C, M, and Y colors. Stand up (step S6). At this time, a display such as “Registration correction calculation error” or “Call a service person” is displayed on the display device 110 (see FIG. 2) such as a display on the operation panel to notify the user of the occurrence of the error.
[0030]
The digital color copying machine 1 according to the present embodiment has a misalignment correction range within which the misregistration amount can be corrected even when the color misregistration correction calculation unit 213 does not perform a normal calculation because the resist pattern is not correctly generated. The same processing as when exceeding is performed.
[0031]
If a registration correction command is issued again after the registration correction and before the user requests a job, the registration correction is repeated again (steps S1 to S5). At this time, the correction was not completed normally at the previous registration correction, but if the correction was completed normally when the registration correction was performed again (for example, an abnormal value was generated due to a detection error of the resist pattern at the previous registration correction. In this case, however, the operation abnormality flag stored in the abnormality determination memory 22 is restored and the latest state is restored. It is displayed on the display device 110. On the other hand, if a registration correction command is not issued, the previous registration correction result is held.
[0032]
Next, the flow of processing until printing ends will be described with reference to the flowchart of FIG. 5 and FIG. The digital color copying machine 1 according to the present embodiment has a print mode such as a character mode and a photo mode, and image processing corresponding to each mode is performed by an image processing unit 24 as image processing means. In the first embodiment of the present invention, image processing that is performed when a photo mode, which is a mode for smoothly reproducing an image such as a photo, is selected will be described.
[0033]
First, the user selects a photo mode using the operation panel 110 (step S11). Next, if there is a job request from the user (YES in step S12), the image processing unit 24 reads information on the calculation abnormality flag from the abnormality determination memory 22 (step S13). At this time, if the calculation abnormality flag is stored in the abnormality determination memory 22 (YES in step S13), the image processing unit 24 performs image processing for calculation abnormality (step S14).
[0034]
With reference to the flowchart of FIG. 6 and FIGS. 7 and 8, the image processing performed at the time of abnormal calculation in step S14 will be described in detail.
[0035]
First, the image processing unit 24 checks whether or not the Y calculation abnormality flag is set (step S101). If the Y calculation abnormality flag is set (YES in step S101), that is, if an uncorrectable color shift occurs in the image forming unit 41Y and an image such as (2) in FIG. The image data of Y is divided into two areas of an edge part and a density flat part by an area discriminating unit 25 as discriminating means. In this specification, a boundary portion between an image (for example, a character image or a graphic image) and a background image, that is, a contour portion of the image is defined as an edge portion, and a non-contour portion of an image other than the background image, that is, an edge is defined. An image region surrounded by the part is defined as a density flat part. In the present embodiment, the edge portion and the density flat portion are the primary for edge detection in the region discriminating unit 25 in which the vertical and horizontal directions are 3 × 3 based on the brightness V of the RGB image data obtained by reading the original. The differential value is determined by obtaining an average value Va of absolute values of the first-order differential result Vh in the horizontal direction and the first-order differential result Vv in the vertical direction, and comparing Va with a predetermined threshold value Vth.
[0036]
That is, when Va ≧ Vth, the image data is determined to be an edge portion, and when Va <Vth, the image data is determined to be a density flat portion. Note that the region determination processing method is not limited to this, and various known methods can be employed.
[0037]
Next, the edge portion is expanded (step S102). The extension of the edge part is to extend the edge part to the density flat part side (inside the image). That is, the density flat portion is reduced simultaneously with the expansion of the edge portion. For example, in the case of an image in which the edge portion is set to 2 dots as shown in (3) in FIG. 8, image data for 3 dots is newly added from the outside of the density flat portion as shown in (5) in FIG. Is replaced with an edge portion, and the edge portion is finally set to 5 dots.
[0038]
Further, the density of the image at the edge portion is set to 0 (step S103). That is, by setting the density of the edge portion to 0 and deleting the edge portion from the image, the image portion where the color shift has occurred is deleted, and the color shift is made inconspicuous. The reason for expanding the edge portion is as shown in (6) in FIG. 8 rather than the image in which the density of the edge portion of the 2-dot image is 0 as shown in (4) in FIG. This is because an image in which the density of an edge portion of an image having an edge portion of 5 dots is set to 0 is more effective in suppressing visual color shift. Further, the width of the edge portion and the width of the extended portion are not limited to the above example.
[0039]
Similar image processing is performed for M (steps S104 to S106) and C (steps S107 to S109). The image processing is not limited to the order of YMC, and may be performed in any order.
[0040]
Returning to FIG. 5, the printing is executed after the image processing is performed (step S16). Further, if there is a job request (YES in step S17), printing is executed after the image processing is performed (step S16).
[0041]
On the other hand, if the calculation abnormality flag is not stored in the abnormality determination memory 22 (NO in step S13), normal image processing (required image forming units 41C to 41Y based on the correction amount calculated by the color misregistration correction calculation unit 213). (Including the correction of the image formation timing) (step S15), and printing is executed (step S16).
[0042]
<Second Embodiment>
Next, a second embodiment of the present invention will be described. The configuration of the digital color copying machine according to the second embodiment is the same as that of the digital color copying machine 1 according to the first embodiment shown in FIGS. Also, the registration correction shown in FIG. 3 is performed in the same manner as in the first embodiment, and a description thereof will be omitted. In the second embodiment of the present invention, image processing performed when a character mode that is a mode for clearly reproducing characters in a color image is selected will be described. That is, image processing performed on the black character portion in order to suppress the color shift of the black character portion in the color image will be described.
[0043]
Hereinafter, the flow of processing until printing is completed will be described with reference to the flowchart of FIG. 9 and FIG.
[0044]
First, the user selects a character mode using the operation panel 110 (step S21). Next, if there is a job request from the user (YES in step S22), it is confirmed whether the read original is a color original including black characters (characters composed of black) (step S23). Whether the read document is a color document or a monochrome document is determined by a known automatic color selection function (ACS). Further, the black character portion is normally determined because the black character in the color image is printed with a single color of K in order to make the color misregistration inconspicuous, and other density flat portions are printed with a mixture of CMYK. It is discriminated based on whether the part is K single color.
[0045]
In the second embodiment, black character discrimination is performed by comparing the saturation W of the image data of the edge portion determined by the region determination unit 25 with a preset threshold value Wr in the black character determination unit 26 which is a black character determination unit. Is determined. When the saturation W is W <Wr, that is, when the saturation is lower than the threshold value Wr, the edge portion is determined to be a K single color and is determined to be a black character. Note that the determination of whether a document is a color document including black characters is not limited to the above method. For example, a mode for a color document including black characters is set, and the determination is made based on whether or not the user has selected this mode. You may do it.
[0046]
When the original is a color original including black characters (YES in step S23), the image processing unit 24 reads information on the calculation abnormality flag from the abnormality determination memory 22 (step S24). At this time, if any one of Y, M, or C stores the calculation abnormality flag in the abnormality determination memory 22 (YES in step S24), the image processing unit 24 performs image processing for calculation abnormality. This is performed (step S25).
[0047]
With reference to the flowchart of FIG. 10 and FIG. 7, the image processing performed at the time of abnormal calculation in step S25 will be described in detail.
[0048]
First, the edge portion of the black character is expanded regardless of the YMC color of the calculation abnormality flag stored in the abnormality determination memory 22 (step S201). The extension of the edge part is to extend the edge part to the density flat part side (inside the image) as in the first embodiment. However, the difference from the first embodiment is that in the first embodiment, the edge portion is expanded only for the image data of the color in which the color misregistration has occurred, whereas in the second embodiment, the black character is expanded. The edge part is extended for all image data of CMYK in the part.
[0049]
Next, all the CMY image data newly replaced from the density flat portion to the edge portion are replaced with K (step S202).
[0050]
In other words, the image processing at the time of abnormality is performed by expanding an edge portion of a black character and using the edge portion as K single-color image data, thereby reducing an area printed by mixing by CMYK, and generating an image in which color misregistration has occurred. The image portion by the means is reduced, and the color shift is less noticeable.
[0051]
Returning to FIG. 9, the printing is executed after the image processing is performed (step S27). Furthermore, if there is a job request (YES in step S28), printing is executed after the above-described image processing is performed (step S27).
[0052]
On the other hand, when the original is not a color original containing black characters (NO in step S23), and when the calculation abnormality flag is not stored in the abnormality determination memory 22 (NO in step S24), normal image processing (color misregistration correction calculation) is performed. Printing is executed (step S27) after the image forming timings of the required image forming units 41C to 41Y are corrected based on the correction amount calculated by the unit 213 (step S26).
[0053]
Note that the image processing in the first embodiment and the second embodiment of the present invention can be performed simultaneously.
[0054]
Even in the case of abnormal calculation, the image processing of the present invention may be further performed after performing registration correction based on past correction data.
[0055]
The present invention is not limited to a digital color copying machine, but can be applied to any image forming apparatus that forms a color image by superimposing a plurality of images, and can be applied to, for example, a printer or a facsimile machine. It is.
[0056]
【The invention's effect】
As described above in detail, in the image forming apparatus and the image forming method according to the first and third aspects of the present invention, even when the color misregistration cannot be corrected, the image forming operation is not stopped and cannot be corrected. By performing image processing on the edge region of the image data created by the image creating means in which color misregistration has occurred, it is possible to form a color image while suppressing deterioration in readability and image quality, and user convenience is improved.
[0057]
In the image forming apparatus and the image forming method according to the second and fourth aspects of the present invention, the image forming operation is not stopped even when correction of color misregistration is impossible, and the image processing is performed on the edge region of the black character portion in the color image. As a result, the color misregistration in the black character portion is suppressed, and the usability of the user is improved.
[Brief description of the drawings]
FIG. 1 is a sectional view of a configuration of a digital color copying machine 1 according to an embodiment of the present invention.
2 is a block diagram showing a configuration of a registration correction related unit 21 of the digital color copying machine 1 shown in FIG.
FIG. 3 is a flowchart showing the flow of registration correction in the digital color copying machine 1 of the present invention.
FIG. 4 is a diagram showing an example of a resist pattern.
FIG. 5 is a flowchart showing a flow of processing until printing is completed in the digital color copying machine 1 according to the first embodiment of the present invention.
FIG. 6 is a flowchart illustrating a flow of image processing performed when color misregistration correction is disabled in the first embodiment of the present invention.
7 is a block diagram showing a main configuration of an image control unit 20 of the digital color copying machine 1 shown in FIG.
FIG. 8 is a diagram illustrating an example in which image processing according to the first embodiment of the present invention is performed on an image.
FIG. 9 is a flowchart illustrating a process flow until printing is completed in the digital color copying machine 1 according to the second embodiment of the present invention.
FIG. 10 is a flowchart illustrating a flow of image processing performed when color misregistration correction is disabled in the second embodiment of the present invention.
[Explanation of symbols]
1: Digital color copier
24: Image processing unit
25; Area discriminator
26; Black character discrimination part
41C-41K; Image forming part
45; transfer belt
48; Pattern detector
214; Calculation abnormality determination unit

Claims (4)

A plurality of image forming means for forming an image based on image data of different colors is provided, and a color image can be formed by multiple transfer of each color image formed by each image forming means onto a transfer means or transfer material In the image forming apparatus,
Detecting means for detecting a color shift of a color image caused by a shift of any transfer position of the image forming means;
An abnormality determining means for determining whether or not the color misregistration can be corrected based on a detection result by the detecting means;
Area discriminating means for discriminating an edge area in the image data;
When it is determined by the abnormality determination means that the color misregistration is uncorrectable, the edge region of the image data created by the image forming means in which the uncorrectable color misregistration has occurred is further expanded, An image forming apparatus comprising: an image processing unit that deletes image data of an extended edge region. A plurality of image forming means for forming an image based on image data of different colors is provided, and a color image can be formed by multiple transfer of each color image formed by each image forming means onto a transfer means or transfer material In the image forming apparatus,
Detecting means for detecting a color shift of a color image caused by a shift of any transfer position of the image forming means;
An abnormality determining means for determining whether or not the color misregistration can be corrected based on a detection result by the detecting means;
Area discriminating means for discriminating an edge area in the image data;
Black character discriminating means for discriminating whether the manuscript image is a color manuscript including black characters;
When it is determined that the color misregistration cannot be corrected by the abnormality determination unit, and the original image is determined to be a color original including black characters by the black character determination unit, the color of each color in the black character is determined. An image forming apparatus comprising: an image processing unit that expands an edge area of image data and further replaces the image data of the expanded edge area with black image data. A plurality of image forming means for forming an image based on image data of different colors is provided, and a color image can be formed by multiple transfer of each color image formed by each image forming means onto a transfer means or transfer material In the image forming method of the image forming apparatus,
A detection step of detecting a color shift of a color image caused by a shift of any transfer position of the image forming means;
An abnormality determination step of determining whether or not the color misregistration can be corrected based on a detection result of the detection step;
An area determination step for determining an edge area in the image data;
When it is determined in the abnormality determination step that the color misregistration is uncorrectable, an edge region of image data formed by the image forming unit in which uncorrectable color misregistration is generated is further expanded, And an image processing step of deleting image data of the extended edge region. A plurality of image forming means for forming an image based on image data of different colors is provided, and a color image can be formed by multiple transfer of each color image formed by each image forming means onto a transfer means or transfer material In the image forming method of the image forming apparatus,
A detection step of detecting a color shift of a color image caused by a shift of any transfer position of the image forming means;
An abnormality determination step of determining whether or not the color misregistration can be corrected based on a detection result of the detection step;
An area determination step for determining an edge area in the image data;
A black character determining step for determining whether the original image is a color original including black characters;
When it is determined that the color misregistration cannot be corrected by the abnormality determination step, and the original image is determined to be a color original including black characters by the black character determination step, the color of each color in the black characters is determined. An image forming method for an image forming apparatus, comprising: expanding an edge area of image data; and replacing the image data of the expanded edge area with black image data.

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