JP2012151695A - Image forming apparatus, image forming method, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus used for a compound machine that forms high-quality images and has high functionality.SOLUTION: An image forming apparatus CM includes a plurality of imaging units 18 arranged on an intermediate transfer belt 10. The image forming apparatus CM assigns image forming operation of the identical color to the plurality of imaging units 18, sets resolution during the image forming operation to each of the imaging units 18 (photoreceptor drums 40K1, 40K2) to which the image forming operation of the identical color is assigned, and thereby controls each of the imaging units 18 to form a different toner image that does not overlap with each other on the intermediate transfer belt 10.

Description

  The present invention relates to an image forming apparatus, an image forming method, and a control program.

Conventionally, a developing device used in a general electrophotographic image forming apparatus has a mechanism for developing four color plates of C (cyan), M (magenta), Y (yellow), and K (black). Was.
There is also known a technique for developing a plate of a special color other than CMYK using a developing device in which the number of plates is expanded to 4 plates or more.

  For example, in Patent Document 1, command analysis of CMYK plate and transparent toner plate is performed for the purpose of providing a control device that can print at least one special color other than four colors of cyan, magenta, yellow, and black. The transparent toner plate is included in the analysis unit, the generation unit that generates the CMYK image data based on the result of the command analysis by the analysis unit, and the attribute flag attached to each pixel of the CMYK image data generated by the generation unit. And an embedding means for embedding a transparent toner attribute obtained by analyzing the above.

  However, in the above-described conventional image forming apparatus, the purpose of adding four or more color plates is only to perform special color printing such as development of a transparent toner plate or a fluorescent toner plate. The function of the forming apparatus could not be improved.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the image quality of an image forming apparatus and to increase the functionality of an image forming apparatus used in a multifunction machine or the like.

  In order to solve the above-described problems and achieve the object, the present invention provides an image carrier, a plurality of image forming units arranged on the image carrier to form toner images of the same color, and an image forming unit. And a control means for controlling the image forming unit according to the resolution set in the setting means to form different toner images that do not overlap each other on the image carrier. It is characterized by that.

  According to another aspect of the invention, there is provided an image forming method executed by an image forming apparatus in which a plurality of image forming units are arranged on an image carrier, and a process of assigning the same color image formation to the plurality of image forming units. And a step of setting a resolution at the time of image formation to each of the image forming portions to which the image formation is assigned, and forming different toner images that do not overlap each other on the image carrier.

  According to another aspect of the present invention, there is provided a control program for controlling, by a computer, an image forming apparatus in which a plurality of image forming units are arranged on an image carrier. Means for assigning, and setting the resolution at the time of image formation in each of the image forming portions to which image formation of the same color is assigned, and functioning as means for forming different toner images that do not overlap each other on the image carrier. Features.

  According to the present invention, in an image forming apparatus in which a plurality of image forming units are arranged on an image carrier, the resolution at the time of image formation is set in each of the image forming units to which image formation of the same color is assigned, Since different toner images that do not overlap each other are formed on the image carrier, an image is formed by a plurality of image forming portions for the same color, and resolution control in one image formation is facilitated, and the height of the formed image is increased. There is an effect that it is possible to easily improve the image quality or to increase the functionality of the image forming apparatus.

FIG. 1 is a schematic diagram showing the mechanism of the image forming apparatus according to the present embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the image forming apparatus. FIG. 3 is a functional block diagram of the image forming apparatus. FIG. 4 is an explanatory diagram of processing when image formation is performed for black (K) with a resolution twice that of other colors (C, M, Y). FIG. 5 is an explanatory diagram of a case where image formation is performed using one of two black photoconductors according to a page to be printed. FIG. 6 is an explanatory diagram of processing for switching the output resolution in the main scanning direction for each page to be printed. FIG. 7 is an explanatory diagram of processing for switching the output resolution for each image area of one image. FIG. 8 is a functional block diagram of an image forming apparatus according to a fourth modification. FIG. 9 is an explanatory diagram in the case where the character image area and the photographic image area are discriminated based on the object information of the printer data and the resolution is switched.

Exemplary embodiments of an image forming apparatus according to the present invention will be explained below in detail with reference to the accompanying drawings.
An image forming apparatus according to the present invention includes a printer, a copier, a facsimile machine, a scanner device, and an MFP (multifunction device, multifunction machine, Multi Function Peripherals) in which a plurality of functions such as a copy, a fax machine, and a printer are housed in a single casing. Etc.) and can be applied to a device having an output function.

FIG. 1 is a schematic diagram showing the mechanism of the image forming apparatus according to the present embodiment.
The image forming apparatus CM includes a copying function and a printer function, and is configured as a column-type color image forming apparatus including five image forming units along the sub-scanning direction (paper conveyance direction).

  In the image forming apparatus CM, the apparatus main body 1 is placed on a paper feed table 2. Further, a scanner 3 is provided on the apparatus main body 1. An automatic document feeder (ADF) 4 is provided on the scanner 3.

  In the apparatus main body 1, a transfer apparatus 20 having an intermediate transfer belt 10 which is a belt-like endless moving member is provided at substantially the center thereof. The intermediate transfer belt 10 is stretched between the driving roller 9 and the two driven rollers 15 and 16. The intermediate transfer belt 10 rotates in the clockwise direction in FIG. 1 when the driving roller 9 is rotated by a driving force from a driving force transmission unit such as a motor. The intermediate transfer belt 10 is configured so that residual toner remaining on the surface after image transfer is removed by a cleaning device 17 provided on the left side of the driven roller 15.

  Above the linear portion of the intermediate transfer belt 10 spanned between the driving roller 9 and the driven roller 15, yellow (Y) and cyan (C) along the moving direction of the intermediate transfer belt 10. , Magenta (M), black (K1), and black (K2) five photosensitive drums 40Y, 40C, 40M, 40K1, and 40K2 (hereinafter, simply referred to as photosensitive drum 40 if not specified). They are arranged at a predetermined interval. Then, five primary transfer rollers 62 are provided inside the intermediate transfer belt 10 so as to face the respective photosensitive drums 40 and sandwich the intermediate transfer belt 10 therebetween.

  Each of the five photosensitive drums 40 can be rotated in the counterclockwise direction in FIG. 1. Around the photosensitive drums 40, a charging device 60, a developing device 61, and the primary transfer roller described above, respectively. 62, a photoconductor cleaning device 63, and a charge removal device 64 are provided, and each constitutes an image forming unit 18. A common exposure device 21 is provided above the five image forming units 18. Then, each image (toner image) formed on each photoconductive drum 40 is sequentially superimposed on the intermediate transfer belt 10 and sequentially transferred.

  On the other hand, on the lower side of the intermediate transfer belt 10, a secondary transfer device 22 serving as a transfer unit that transfers an image on the intermediate transfer belt 10 to a sheet of recording paper is provided. The secondary transfer device 22 has a secondary transfer belt 24, which is an endless belt, spanned between two rollers 23, 23, and the secondary transfer belt 24 is moved to the driven roller 16 via the intermediate transfer belt 10. It comes to push. The secondary transfer device 22 collectively transfers the toner images on the intermediate transfer belt 10 to a sheet fed between the secondary transfer belt 24 and the intermediate transfer belt 10 at a predetermined transfer position.

  A fixing device 25 that fixes the toner image on the paper is provided downstream of the secondary transfer device 22 in the paper conveyance direction. In the fixing device 25, a pressure roller 27 is pressed against the fixing belt 26 which is an endless belt.

  Note that the secondary transfer device 22 also functions to convey the sheet after image transfer to the fixing device 25. Further, the secondary transfer device 22 may be a transfer device using a transfer roller or a non-contact charger. Below the secondary transfer device 22, a paper reversing device 28 is provided for reversing the paper when images are formed on both sides of the paper.

FIG. 2 is a block diagram illustrating a schematic configuration of a control system of the image forming apparatus.
The image forming apparatus CM includes a CPU 100 that controls the entire image forming apparatus CM, a ROM 102 that stores a control program and control data in a nonvolatile manner, a RAM 104 that temporarily stores various data and is used as a work area, NVRAM 106 that stores non-volatile data that can be updated such as user setting data even when the power is turned off, a storage device 108 that is configured as a hard disk drive that is used as a storage area for image data accumulation or database, An operation unit 110 having an operation unit and a display unit and functioning as a user interface; and a network control unit 112 connected to a network such as Ethernet (registered trademark) and controlling communication with an external device. Yes.

  Further, the image forming apparatus CM controls a scanner 114 that reads a paper document, a plotter 116 that prints on a recording sheet, and exchanges of data between the scanner 114, the plotter 116, and the storage device 108. It has a controller 118 and a main bus 120 connecting them.

  An image forming program for executing image forming processing in the image forming apparatus CM according to the present embodiment is stored in the ROM 102. Note that the image forming program may be provided by being recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), and a DVD as a file in an installable or executable format. In this case, the image forming program is loaded onto the main storage device by being read from the recording medium and executed by the image forming apparatus CM, and each unit described in the software configuration is generated on the main storage device. You can do it. Further, the image forming program may be stored on a computer connected to a communication network such as the Internet and provided by being downloaded via the network.

Here, an outline operation of the image forming apparatus CM will be described.
When color copying is performed by the image forming apparatus CM, the document is set on the document table 30 of the automatic document feeder 4. When the document is manually set, the automatic document feeder 4 is opened, the document is set on the contact glass 32 of the scanner 3, and the automatic document feeder 4 is closed and pressed.

  When a start key (not shown) of the operation unit 110 (see FIG. 2) is pressed, when the document is set on the automatic document feeder 4, the document is fed onto the contact glass 32. When the document is manually set on the contact glass 32, the scanner 3 is immediately driven, and the first traveling body 33 and the second traveling body 34 start traveling. Then, light is emitted from the light source of the first traveling body 33 toward the document, and reflected light from the document surface is directed to the second traveling body 34, and the light is reflected by the mirror of the second traveling body 34. The light enters the reading sensor 36 through the imaging lens 35 and the content of the original is read.

  Further, when the start key is pressed, the intermediate transfer belt 10 starts to rotate. At the same time, the photosensitive drums 40Y, 40C, 40M, 40K1, and 40K2 start rotating, and yellow (Y), cyan (C), magenta (M), and black (K1) are formed on the photosensitive drums. Then, the operation of forming each monochrome toner image of black (K2) is started. The toner images of the respective colors formed on the respective photosensitive drums are sequentially transferred while being superimposed on the intermediate transfer belt 10 that rotates in the clockwise direction in FIG. 5, and a full-color composite color image is formed there. Is formed.

  On the other hand, when the start key described above is pressed, the paper feed roller 42 of the selected paper feed stage in the paper feed table 2 rotates, and the sheet (see FIG. 1) is fed out, and is separated into one sheet by the separation roller 45 and conveyed to the sheet feeding path 46. The sheet is conveyed by a conveyance roller 47 to a sheet feeding path 48 in the apparatus main body 1, hits a registration roller 49 and temporarily stops.

  In the case of manual paper feeding, the paper set on the manual tray 51 is fed out by the rotation of the paper feeding roller 50, and is separated into one sheet by the separation roller 52 and conveyed to the manual paper feeding path 53. Then, it hits the registration roller 49 and temporarily stops. The registration roller 49 starts to rotate at an accurate timing in accordance with the composite color image on the intermediate transfer belt 10, and feeds the temporarily stopped paper between the intermediate transfer belt 10 and the secondary transfer device 22. . Then, a color image is transferred onto the paper by the secondary transfer device 22. Note that the sheet may be temporarily stopped by a stopper instead of the registration roller 49.

  The sheet on which the color image has been transferred is conveyed to the fixing device 25 by the secondary transfer device 22 that also functions as a conveying device, where the transferred color image is fixed by applying heat and pressure. Thereafter, the sheet is guided to the discharge side by the switching claw 55, discharged onto the discharge tray 57 by the discharge roller 56, and stacked there. When the double-sided copy mode is selected, the sheet on which an image is formed on one side is conveyed to the sheet reversing device 28 side by the switching claw 55, reversed there and guided again to the transfer position A, and this time the image is printed on the back side. After the formation, the paper is discharged onto a paper discharge tray 57 by a discharge roller 56.

Next, a specific image forming operation will be described.
First, an image is formed at 600 dpi for yellow (Y), cyan (C), and magenta (M), and an image is formed at 1200 dpi using black (K1) and black (K2) for black (K). The case where it does is demonstrated.

FIG. 3 is a functional block diagram of the image forming apparatus.
First, the CPU 100 of the image forming apparatus CM sharpens and smoothes 600 dpi input RGB data (600 dpi each for R data, G data, and B data) so as to improve reproducibility when output to the plotter 116. It functions as a filter processing unit 131 that performs processing and the like. More specifically, the filter processing unit 131 performs sharpening / smoothing processing in the operation unit 110 according to the attribute information (image area separation signal) decoded according to the set image quality mode. For example, the filter processing unit 131 performs sharpening processing in order to clarify and stand out characters in the character document mode, and performs smoothing processing to smoothly express gradation in the photo mode.

  Subsequently, the CPU 100 functions as the color correction processing unit 132 and performs color space conversion (RGB → CMYK) and color correction on the sharpened or smoothed RGB data.

  As a result, the 600 dpi R data, G data, and B data respectively input are 600 dpi C (cyan) data, M (magenta) data, Y (yellow) data, and K (black) data.

Next, the CPU 100 functions as the γ conversion processing unit 133 and performs density conversion based on the obtained C data, M data, Y data, and K data.
Subsequently, the CPU 100 functions as a halftone processing unit 134. For the C data, M data, and Y data, the halftone processing is performed with 600 dpi respectively, and the data after the halftone processing is transferred to the plotter 116 via the main bus 120. Output via.

  The K data is doubled from 600 dpi to 1200 dpi, subjected to halftone processing, and output as K1 data and K2 data to the plotter 116 via the main bus 120.

FIG. 4 is an explanatory diagram of processing when image formation is performed for black (K) with a resolution twice that of other colors (C, M, Y).
First, the plotter 116 forms an image in the main scanning direction 1200 dpi and the sub-scanning direction 600 dpi as shown in FIG. 4A based on the K1 data. Similarly, the plotter 116 forms an image based on the K2 data in the main scanning direction 1200 dpi and the sub-scanning direction 600 dpi, as shown in FIG. 4B.

In this case, the plotter 116 performs image formation alternately line by line as shown in FIGS. 4A and 4B under the control of the CPU 100.
That is, in the example shown in FIG. 4, the plotter 116 performs image formation on odd lines (first line, third line, fifth line,...) Based on the K1 data. Further, the plotter 116 creates an image of even lines (second line, fourth line, sixth line,...) Based on the K2 data.

  As a result, when the images formed based on the K1 data and the K2 data are added together, 1200 dpi image data can be formed in both the main scanning direction and the sub-scanning direction. Therefore, a black image of main scanning 1200 dpi and sub scanning 1200 dpi can be formed on the printing paper.

  In the above description, the black photosensitive drums are multiplexed to form the photosensitive drums 40K1 and 40K2. However, the cyan photosensitive drum, the magenta photosensitive drum, or the yellow photosensitive drum is described. Can be configured to be multiplexed in the same manner. When high definition is to be achieved in full color, it is necessary to multiplex all of the cyan photosensitive drum, the magenta photosensitive drum, and the yellow photosensitive drum.

[First Modification]
Although the above description has always been for the case where the photosensitive drum 40K1 and the photosensitive drum 40K2 are used, it is also possible to use only one of them.
Here, a first modification example in which image formation is performed using one of the two black photosensitive drums will be described.

FIG. 5 is an explanatory diagram in a case where image formation is performed using one of the two black photosensitive drums according to the page to be printed.
In the image forming apparatus CM of the present embodiment, the case where the photosensitive drum 40K1 and the photosensitive drum 40K2 are used (see FIG. 4) and the case where only the photosensitive drum 40K1 (or the photosensitive drum 40K2) is used are switched. It is possible to

As shown in FIG. 5, a page on which an image is formed using only the photosensitive drum 40K1 and a page on which an image is formed using both the photosensitive drum 40K1 and the photosensitive drum 40K2 are switched as shown in FIG. Image formation.
That is, for a page on which image formation is performed only with the photosensitive drum 40K1, as shown in FIG. 5, image formation is performed with 1200 dpi main scanning and 600 dpi sub-scanning.

  In this way, by switching between using one of the two black photosensitive drums 40K1 and 40K2 for each page to be printed or using both of the photosensitive drums, each page is printed. It is possible to perform image processing at an optimal resolution for image data and form an image.

  For example, a photographic image page is output at 1200 dpi and sub-scanning 600 dpi, and a character image page is output at 1200 dpi and sub-scanning 1200 dpi. Thus, a page of a photographic image (or a photographic image mainly) for which a large dot is to be formed and a smooth image output is desired is formed at a low resolution of 1200 dpi in the main scanning direction and 600 dpi in the sub scanning direction. In addition, on a page of a character image (or a character image main body) for which a finer dot is formed and a sharp image output is desired, an image is formed with a high resolution of 1200 dpi in the main scanning direction and 1200 dpi in the sub-scanning direction.

In this way, it is possible to perform optimum image formation for each page by switching the resolution for each page.
In this case, it is also possible to multiplex the photosensitive drum for cyan, the photosensitive drum for magenta, or the photosensitive drum for yellow similarly.

[Second Modification]
Next, the process of the 2nd modification which switches the output resolution of a main scanning direction is demonstrated.
FIG. 6 is an explanatory diagram of processing for switching the output resolution in the main scanning direction for each page to be printed.
In the photosensitive drum 40K1 and the photosensitive drum 40K2, the resolution in the main scanning direction can be appropriately changed and switched under the control of the CPU 100.
As the resolution in the main scanning direction, a desired resolution is set for each page to form an image.
As shown in FIG. 6, on the photosensitive drum 40K1 and the photosensitive drum 40K2, an image is formed in the main scanning direction 600 dpi and the sub-scanning direction 600 dpi.

As a result, when the image formed on the photosensitive drum 40K1 and the image formed on the photosensitive drum 40K2 are combined, an image can be formed in the main scanning direction 600 dpi and the sub-scanning direction 1200 dpi.
Therefore, an image can be formed by switching the output resolution in the main scanning direction for each page to be printed. As a result, image processing can be performed for each page with image processing at the optimum resolution for the image data.

The above description is for the case where an image is formed with a resolution in the main scanning direction of 600 dpi. However, the resolution in the main scanning direction can be arbitrarily set as long as it is equal to or lower than the maximum resolution.
In this case, it is also possible to multiplex the photosensitive drum for cyan, the photosensitive drum for magenta, or the photosensitive drum for yellow similarly.

[Third Modification]
FIG. 7 is an explanatory diagram of processing for switching the output resolution for each image area of one image.
In the following description, the photosensitive drum 40K1 forms an image with a resolution of 600 dpi in the main scanning direction and a sub-scanning direction of 600 dpi, and the photosensitive drum 40K2 forms an image with a resolution of 300 dpi in the main scanning direction and 300 dpi in the sub-scanning direction. Will be described as an example.

In this case, the character image area uses the photoconductor drum 40K1 to form finer dots to output a sharp image, and the photographic image area uses the photoconductor drum 40K2 to form large dots. As a result, a smooth image is formed.
In the case of the example shown in FIG. 7, it is assumed that a character image area CH and two photographic image areas PH1 and PH2 exist in the image forming area GA as shown in FIG. 7C.

Therefore, with respect to the character image region CH, as shown in FIG. 7A, emphasis is placed on the sharpness of details, and a character image is formed by the photosensitive drum 40K1 with a resolution of 600 dpi in the main scanning direction and 600 dpi in the sub-scanning direction. . On the other hand, with respect to the two photographic image areas PH1 and PH2, as shown in FIG. 7B, the photosensitive drum 40K2 uses the photosensitive drum 40K2 to obtain a smooth image with a stable dot shape and 300 dpi and a sub-scanning direction of 300 dpi. A photographic image is formed with a resolution of.
As described above, since an image is formed with an optimal resolution for each image forming region, it is easier to see and high-quality image formation can be performed.

[Fourth Modification]
In the above description of the third modified example (FIG. 7), it has been described that the character image region CH and the photographic image regions PH1 and PH2 are known in advance. In this case, the resolution is switched between the image area and the photographic image area.

FIG. 8 is a functional block diagram of an image forming apparatus according to a fourth modification.
In FIG. 8, the same parts as those in FIG. 3 are denoted by the same reference numerals.
First, the CPU 100 of the image forming apparatus CM functions as the filter processing unit 131, and performs sharpening processing, smoothing processing, and the like so as to improve reproducibility when output to the plotter 116 with respect to 600 dpi input RGB data. . Subsequently, the CPU 100 functions as the color correction processing unit 132, performs color space conversion (RGB → CMYK) on the sharpened or smoothed RGB data, performs color correction, and functions as the γ conversion processing unit 133. Then, density conversion is performed based on the obtained C data, M data, Y data, and K data, and the result is output to the halftone processing unit 134A.

  In parallel with these, the CPU 100 functions as the feature amount extraction unit 135, performs edge extraction based on 600 dpi input RGB data, and based on whether the edge amount is greater than a predetermined determination threshold value. The character image area and the photographic image area are identified.

  That is, the character image area has a larger edge amount than the photographic image area. Therefore, when the edge amount exceeds the determination threshold value, the feature amount extraction unit 135 determines that the character image area and outputs the determination result to the halftone processing unit 134A. On the other hand, when the edge amount is equal to or smaller than the determination threshold value, the feature amount extraction unit 135 determines that it is a photographic image region and outputs the determination result to the halftone processing unit 134A.

  Subsequently, the CPU 100 functions as the halftone processing unit 134A, and the K data corresponding to the character image area is formed with fine dots in order to emphasize the sharpness of the details, so that both the main scanning direction and the sub-scanning direction are used. The data is output as K1 data to be processed by the photosensitive drum 40K1 at 600 dpi. On the other hand, the K data corresponding to the photographic image area is output as K2 data to be processed by the photosensitive drum 40K2 at 300 dpi in both the main scanning direction and the sub-scanning direction so that a smooth image can be obtained with a stable dot shape. .

  As described above, according to the fourth modification, the character image area and the photographic image area are automatically detected, and an image is formed by switching the output resolution for each image portion, thereby obtaining an optimum resolution for each image portion. Can perform image processing to form an image.

[Fifth Modification]
In the fourth modification described above, the character image area and the photographic image area are discriminated based on the extraction result of the feature amount extraction unit 135. However, in the fifth modification, the image forming apparatus CM is used as a printer. This is a function for discriminating a character image area and a photographic image area from object information of printer data inputted from an external device such as a personal computer via a communication network such as a LAN (not shown) and a network control unit 112. .

FIG. 9 is an explanatory diagram in the case where the character image area and the photographic image area are discriminated based on the object information of the printer data and the resolution is switched.
When the printer data is input via a communication network such as a LAN (not shown) and the network control unit 112, the CPU 100 of the image forming apparatus CM extracts the object information included in the input printer data to obtain a character image area. And a photographic image area are detected.

  The CPU 100 functions as a filter processing unit 131B, a color correction processing unit 132B, and a γ conversion processing unit 133B, and delivers (outputs) C data, M data, Y data, and K data to the halftone processing unit 134B.

  Subsequently, the CPU 100 functioning as the halftone processing unit 134B determines the character image area and the photographic image area based on the object information of the printer data, and the K data corresponding to the character image area has fine sharpness. Since the image is formed with fine dots for emphasis, the main scanning direction and the sub-scanning direction are set to 600 dpi and output as K1 data to be processed by the photosensitive drum 40K1. On the other hand, the K data corresponding to the photographic image area is output as K2 data to be processed by the photosensitive drum 40K2 at 300 dpi in both the main scanning direction and the sub-scanning direction so that a smooth image can be obtained with a stable dot shape. .

As described above, according to the fifth modification, the character image area and the photographic image area are automatically detected based on the object information of the printer data, and the image is formed by switching the output resolution for each image portion. Images can be formed by performing image processing at an optimal resolution for each image part.
In this case, it is also possible to multiplex the photosensitive drum for cyan, the photosensitive drum for magenta, or the photosensitive drum for yellow similarly.

[Other variations]
In the above description, the same color image formation is assigned to the plurality of image forming units 18, and the image forming units 18 to which the same color image formation is assigned (in the above example, the image forming units corresponding to the photosensitive drums 40K1 and 40K2). In each of the image units 18), the resolution at the time of image formation is set, and different toner images that do not overlap each other are formed on the intermediate transfer belt 10, but a part of them overlaps on the intermediate transfer belt 10. It can also be configured to form a toner image. For example, in the case of the third modified example, when performing edge enhancement of a photographic image area, a toner image may be formed in the edge area in the same manner as the character image area.

  The control program executed by the image forming apparatus according to the present embodiment includes a module configuration including the above-described filter processing unit, color correction processing unit, γ conversion processing unit, and intermediate processing unit, and further includes a module configuration including a feature extraction unit. It has become.

  As actual hardware, a CPU (processor) reads the control program from the ROM and executes it, so that the above-described units are loaded on the main storage device, and a filter processing unit, a color correction processing unit, a γ conversion processing unit, an intermediate process And a feature extraction unit are generated on the main memory.

  In the above embodiment, the case where the image forming apparatus has a copy function and a printer function has been described. However, a multifunction machine having at least two functions of a copy function, a printer function, a scanner function, and a facsimile function, or The present invention can be applied to any image forming apparatus such as a copying machine, a printer, and a facsimile machine.

10 Intermediate transfer belt (image carrier)
18 Image forming unit (image forming unit)
40 Photosensitive drum (image forming unit)
40C photosensitive drum (image forming unit)
40M photosensitive drum (image forming unit)
40Y Photosensitive drum (image forming unit)
40K1 photosensitive drum (image forming unit)
40K2 photosensitive drum (image forming unit)
100 CPU
102 ROM
104 RAM
106 NVRAM
108 Storage Device 110 Operation Unit 112 Network Control Unit 114 Scanner 116 Plotter 118 System Controller 120 Main Bus 131, 131B Filter Processing Unit 132, 132B Color Correction Processing Unit 133, 133B Gamma Conversion Processing Unit 134, 134A, 134B Halftone Processing Unit 135 Feature extraction unit CH Character image area CM Image forming device GA Image forming area PH1, PH2 Photo image area

JP 2009-55601 A

Claims (10)

An image carrier;
A plurality of image forming units arranged on the image carrier to form toner images of the same color;
Setting means for setting the resolution at the time of image formation;
Control means for controlling the image forming unit according to the resolution set in the setting means to form different toner images that do not overlap each other on the image carrier;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the control unit causes the plurality of image forming units to which the image formation of the same color is assigned to form the toner image at a position shifted along a sheet conveyance direction.   The image forming apparatus according to claim 2, wherein the control unit sets the same resolution at the time of image formation of the plurality of image forming units to which image formation of the same color is assigned.   The image forming apparatus according to claim 1, wherein the control unit sets a different resolution at the time of image formation for each of the plurality of image forming units to which image formation of the same color is assigned.   The control means divides the image into a plurality of image areas according to the image formation contents, and sets the image areas having different resolutions according to the image formation contents to each of the plurality of image forming sections to which the image formation of the same color is assigned. The image forming apparatus according to claim 4, wherein:   6. The image region corresponding to the image formation content includes at least a character formation region and a photo formation region, and the resolution of the character formation region is set higher than the resolution of the photo formation region. Image forming apparatus.   The said control means discriminate | determines the said image formation content based on the object data contained in the said print data, when performing image formation based on the input print data. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the same color is black. In an image forming method executed by an image forming apparatus in which a plurality of image forming units are arranged on an image carrier,
Assigning image formation of the same color to a plurality of image forming units;
A process of setting a resolution at the time of image formation in each of the image forming units to which image formation of the same color is assigned, and forming different toner images that do not overlap each other on the image carrier;
An image forming method comprising: A control program for controlling an image forming apparatus in which a plurality of image forming units are arranged on an image carrier by a computer,
The computer,
Means for assigning image formation of the same color to a plurality of image forming units;
Means for setting a resolution at the time of image formation in each of the image forming units to which image formation of the same color is assigned, and forming different toner images that do not overlap each other on the image carrier;
A control program characterized by functioning as

Images