JP4701769B2 - Image forming method - Google Patents

Description

  The present invention relates to a technique for improving the image quality of an image formed by an image forming apparatus.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for performing a fixing process again on a toner image fixed on one side of a recording sheet. According to this technique, once the toner once fixed is reheated, the fixing unevenness generated in the first fixing process is eliminated, and an image with good glossiness can be obtained. In an image forming apparatus, in addition to a mode for performing a single fixing process, a mode for outputting a glossy image by performing a fixing process twice, the user can output an image by a single fixing process. It is possible to selectively use the case where priority is given to the speed of the image and the case where priority is given to image output of high quality by two fixing processes. However, if the number of times of fixing is different, even if an image with the same pattern is formed on the recording paper, the density of the image is different between the image that has been subjected to the fixing process once and the image that has been subjected to the fixing process twice. On the other hand, the problem of being different arises.

As a technique for preventing a density difference from being caused by such a difference in the number of fixings, for example, there is a technique disclosed in Patent Document 2. The image forming apparatus disclosed in Patent Document 2 forms a test pattern on the surface of the recording paper and performs a first fixing process, and then reverses the recording paper to form a test pattern on the back surface. Fixing process is performed again. Next, the image forming apparatus reads an image formed on the front surface (an image subjected to two fixing processes) and an image formed on the back surface (an image subjected to only one fixing process), The density of each image is detected. After the density detection of the test pattern, the image forming apparatus, based on the detected image density on the front surface and the image density on the back surface, the image on the front surface and the image on the back surface, that is, the image on which the fixing process is performed twice. In addition, the image forming process is performed so that the density difference does not occur when the fixing process is performed once, thereby preventing the density difference due to the difference in the number of fixings.
JP 2003-280451 A Japanese Patent Laid-Open No. 9-27879

  By the way, in the PPC paper normally used in the image forming apparatus, when the image is formed on both sides, the image formed on the back side is slightly seen through from the front side. For this reason, in the apparatus disclosed in Patent Document 2, the density of the image formed on the front surface (image that has been subjected to two fixing processes) and the image formed on the rear surface (only one fixing process are performed). When detecting the density of the image), a density different from the original density is detected under the influence of the image formed on the opposite surface. After the density detection of the test pattern is performed, tone correction is performed based on the detected density, that is, a density different from the original density, so that the density difference caused by the difference in the number of fixings is accurately corrected. I couldn't.

  The present invention has been made under the above-described background, and an object thereof is to form an image so that there is no difference in image quality even if the number of times of fixing is different.

In order to solve the above-described problems, the present invention provides a test image transfer process in which a toner image of a predetermined test image is transferred to one surface of a recording medium, and a toner image transferred to the recording medium in the test image transfer process. , the first and the test image fixing process for fixing before type recording medium in the second fixing number of times fixed number or set, the test image fixed before type recording medium in the first fixing set number of A reading process for reading a toner image , a toner image of the test image fixed on the recording medium by the second fixing number, a density detecting process for detecting a density of each toner image read by the reading process, and a recording so that the density of the toner image to be fixed is transferred to the medium in the first fixing times the target concentration predetermined image forming condition of the toner image, Oite the concentration detecting step Issued, the first set in accordance with the density of the toner image fixing has been the test image by fixing the number, concentration target of the toner image is transferred onto the recording medium is fixed by the second fixing times A setting process for setting the image forming condition of the toner image in accordance with the density of the toner image of the test image fixed at the second fixing number detected in the density detection process so as to obtain a density; an image input process in which an image is inputted, the fixing times setting step of setting the fixing times of the toner image of the image input in the image input step, the fixing of the toner image of the image input by the image input step When the toner image is fixed on the recording medium at the first fixing number set in the number setting process, the setting process is performed according to the density of the toner image of the test image fixed at the first fixing number. Set in Have been transferred to form a recording medium in accordance with image forming conditions, when fixing a toner image of the image input in the image input step to the recording medium in the second fixing times set by the fixing number setting process An image transfer process in which the toner image is formed according to the image forming conditions set in the setting process in accordance with the density of the toner image of the test image fixed at the second fixing number, and transferred to a recording medium ; the toner image formed on the recording medium by the image transfer process, to provide an image forming method and an image fixing process for fixing before type recording medium by the number of times set by the fixing number setting process.

  According to the present invention, it is possible to form an image so that there is no difference in image quality even if the number of fixings is different.

[First Embodiment]
[Constitution]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus according to the first embodiment of the present invention. This image forming apparatus is an image forming apparatus having a tandem configuration using an intermediate transfer belt, and includes four processing systems corresponding to respective colors of Y (yellow), M (magenta), C (cyan), and K (black). .

  The image forming apparatus includes a control unit 100 including a CPU, a ROM, a RAM, and the like. The control unit 100 is connected to various buttons (not shown) for operating the image forming apparatus and a liquid crystal display for displaying various menus with a touch panel. When a button or a touch panel is operated by the user of the image forming apparatus, the control unit 100 controls each unit of the image forming apparatus according to a program stored in the ROM, and performs processing such as copying a document.

The document reading unit 10 is a unit that reads a document and generates an image signal of the read document, and includes a light source 11, a platen glass 12, a reflection mirror 13, a lens 14, and a solid-state image sensor 15. The light emitted from the light source 11 and reflected by the original placed on the platen glass 12 is reflected by the reflection mirror 13. Then, the light reflected by the reflection mirror 13 enters the solid-state image sensor 15 through the lens 14. The solid-state imaging device 15 converts incident light into an electrical signal by an element corresponding to each color of R (red), G (green), and B (blue), and generates and outputs an image signal representing an image of each color. To do.
The RGB image signal is digitally processed by the image processing unit 110 and subjected to various processes such as screen processing, density correction, and magnification correction. In the image processing unit 110, color conversion processing is performed on the image signal that has been subjected to various types of processing, and Y (yellow), M (magenta), C (cyan), and K (black) color images. A signal is generated. The image signals of each color of YMCK are output from the image processing unit 110 and input to the image forming unit 20 that forms an image.

  The image forming unit 20 superimposes the units 30Y, 30M, 30C, and 30K that form toner images of each color of YMCK and the toner images for four colors that are formed on the units 30Y, 30M, 30C, and 30K, and then intermediate transfer belt. The primary transfer rolls 31Y, 31M, 31C, and 31K that primarily transfer to 40, and the secondary transfer roll 32 that presses the recording paper P (recording medium) onto the intermediate transfer belt 40 on which the toner images for four colors are superimposed and primarily transferred. And. Further, a belt cleaner 33 for removing residual toner on the intermediate transfer belt 40 is provided on the upstream side of each unit 30 in the moving direction of the intermediate transfer belt 40. The units 30Y, 30M, 30C, and 30K have the same configuration except that the color of the toner image to be formed is different. Therefore, in the following description, the unit 30Y that is one of them will be described. Explanation of other units is omitted.

  When the unit 30Y receives supply of a photosensitive drum 34 on which a toner image is formed, a charger 35 for charging the photosensitive drum 34, and an image signal of a color (Y) corresponding to the unit 30Y, the unit 30Y uses the image signal. The exposure light 36 modulated in this manner is irradiated onto the photosensitive drum 34 at a timing corresponding to the image signal, and an exposure unit 36 for forming an electrostatic latent image, and the photosensitive drum 34 on which the electrostatic latent image is formed are provided with a unit 30Y. A developing device 37 of a two-component development system that forms a toner image by adhering a toner of a color (Y) corresponding to the photosensitive drum 34, and the photosensitive drum 34 after the formed toner image is primarily transferred to the intermediate transfer belt 40. And a cleaning device 38 that removes residual toner by cleaning. Each toner cartridge 39 that supplies toner to each developing device 37 is provided above the image forming unit 20.

  Each photoconductor drum 34 rotates in a predetermined direction and is uniformly charged by each charger 35. When laser light is irradiated onto the photosensitive drum 34 corresponding to the image signals of each color from the exposure unit 36, the photosensitive drum 34 is exposed to form an electrostatic latent image. Around each photosensitive drum 34, each developing device 37 that accommodates YMCK color toner is disposed. The electrostatic latent image formed on each photosensitive drum 34 is stored for each photosensitive drum 34. Each of the developing devices 37 disposed in the image is developed to form a toner image of each color.

  On the other hand, the intermediate transfer belt 40 in contact with the four photosensitive drums 34 is looped over the opposing rolls 41 and 42 and the primary transfer roll 31 and circulates in the direction of arrow A. The toner images of the respective colors formed on the respective photosensitive drums 34 are superimposed and transferred onto the intermediate transfer belt 40 by the respective primary transfer rolls 31 disposed at the respective transfer positions. The color toner images superimposed and transferred on the intermediate transfer belt 40 are transferred from the paper tray 50 (or the paper trays 51 and 52) to the recording paper P conveyed by the paper conveyance roll 50a (or the paper conveyance rolls 51a and 52a). The images are transferred onto the recording sheet P by the opposing roll 41 and the secondary transfer roll 32 that are superimposed and form a nip portion with the intermediate transfer belt 40 interposed therebetween. The recording paper P on which each color toner image has been transferred is heated and pressed by a fixing device 60 having a heating roll and a pressure roll. As a result, each color toner image is fixed on the recording paper P to form an image.

  Further, the image forming apparatus is provided with a discharge tray 70 and a discharge tray 71. The recording paper P on which the toner image is formed is discharged to the discharge tray 70 or the discharge tray 71 by each roll provided in the image forming apparatus.

The image forming apparatus includes transport rolls 80, 81, and 82. The image forming apparatus forms an image on one side of the recording paper P, and when performing the fixing process once, the recording paper P heated and pressurized by the fixing device 60 to fix the image is transferred to the transport roll 80. To the discharge tray 70.
Further, when the image forming apparatus performs image formation on both sides of the recording paper P, the recording paper P heated and pressed by the fixing device 60 and the image fixed thereon is switched back by the conveyance roll 80, It is sent again to the secondary transfer roll 32 by the transport rolls 81 and 82. Then, the recording paper P on which images are formed on both sides is discharged to the discharge tray 71 via the secondary transfer roll 32 and the fixing device 60.
Further, when the fixing process is performed twice on the image on one side, the recording paper P is sent again to the secondary transfer roll 32 by the transport rolls 81 and 82 without performing the switchback. Then, the recording paper P that has passed through the secondary transfer roll 32 and the fixing device 60 is discharged to the discharge tray 70.

[Operation]
Next, the operation of this embodiment will be described.
When the user performs a predetermined operation on the touch panel, the control unit 100 controls the liquid crystal display, and an image quality correction menu screen (see FIG. 3) is displayed. Next, in the liquid crystal display provided with the touch panel, when the user touches the “image quality correction” portion of the screen shown in FIG. 3, the control unit 100 controls the image forming unit 20, as shown in FIG. 4. Then, an image of a test pattern having a different image density for each rectangular area is transferred to the recording paper P (step SA1). When the transfer of the test pattern is completed, the control unit 100 sends the recording paper P to the fixing device 60. The recording paper P sent to the fixing device 60 is heated and pressurized by the fixing device 60 (step SA2), and the recording paper P on which the image has been fixed by this heating and pressure is discharged to the discharge tray 70 (step S2). SA3).

  Next, the control unit 100 controls the image forming unit 20 to transfer an image of a test pattern having a different image density for each rectangular area to the recording paper P as shown in FIG. 4 (step SA4). When the transfer of the test pattern is completed, the control unit 100 sends the recording paper P to the fixing device 60. Next, the recording paper P sent to the fixing device 60 is heated and pressurized by the fixing device 60 (step SA5). The heated and pressurized recording paper P is sent again to the secondary transfer roll 32 by the transport rolls 81 and 82. Then, the recording paper P sent again to the secondary transfer roll 32 passes between the secondary transfer roll and the opposing roll 41 without contacting the intermediate transfer belt 40 and is sent again to the fixing device 60 ( Step SA6). The recording paper P sent to the fixing device 60 again is heated and pressurized again by the fixing device 60 (step SA7). The recording paper P that has been subjected to the second fixing process is discharged to the discharge tray 71 (step SA8).

Next, the recording paper P discharged to the discharge tray 70, that is, the recording paper P that has undergone only one fixing process is placed on the platen glass 12. Thereafter, when the user presses the start button provided on the image forming apparatus and instructs to read the image (step SA9; YES), the test pattern on the recording paper P placed thereon is read by the document reading unit 10. (Step SA10). Next, the image forming apparatus detects the image density of the read test pattern (step SA11), and compares the detected image density with the target density of the rectangular area of the test pattern stored in advance in the ROM. Then, based on the comparison result, a correction value for correcting the input image is set so that the density of the toner image formed on the recording paper P and subjected to one fixing process becomes a predetermined target density. (Step SA12).
For example, when the density of the rectangular area output at a density of 20% is only 15% in the read image, the image forming apparatus sets the correction value so that the 15% density portion in the read image becomes the target density of 20%. The set correction value is stored on the RAM. When the density of the rectangular area output at 80% density is 85% in the read image, the image forming apparatus corrects the correction value so that the 85% density portion in the read image becomes the target density 80%. And the set correction value is stored in the RAM.

  Next, the recording paper P discharged to the discharge tray 71, that is, the recording paper P that has been subjected to the fixing process twice, is placed on the platen glass 12. Thereafter, when the user presses the start button provided on the image forming apparatus and instructs to read the image (step SA13; YES), the test pattern on the recording paper P placed thereon is read by the document reading unit 10. (Step SA14). Next, the image forming apparatus detects the image density of the read test pattern (step SA15), and compares the detected image density with the target density of the rectangular area of the test pattern stored in advance in the ROM. Then, based on the comparison result, the correction value for correcting the input image is adjusted so that the density of the toner image formed on the recording paper P and subjected to the fixing process twice is a predetermined target density. (Step SA16).

  After the correction value has been set, the user places the document on the platen glass 12, selects the standard image quality mode and presses the start button on the menu screen shown in FIG. 3, and the image of the placed document is displayed. The document is read by the document reading unit 10. The image signal of the image read by the document reading unit 10 is digitally processed by the image processing unit 110 and subjected to various processes such as screen processing, density correction, and magnification correction. When density correction is performed, density correction is performed using the correction value set in step SA12 described above. Then, color conversion processing is performed on the image signal that has been subjected to various types of processing, and is converted into image signals of Y (yellow), M (magenta), C (cyan), and K (black) colors. The image signals of each color of YMCK are output from the image processing unit 110 and input to the image forming unit 20 that forms an image. In the image forming unit 20, each color toner image is formed based on the image signal output from the image processing unit 110, and the toner image is transferred to the intermediate transfer belt 40. The toner image transferred to the intermediate transfer belt 40 is transferred onto the recording paper P by the secondary transfer roll 32 and the opposing roll 41. The recording paper P to which the toner image has been transferred is heated and pressurized by the fixing device 60 and then discharged to the discharge tray 70 by the transport roll 80.

  On the other hand, when the user places a document on the platen glass 12 and selects the high image quality mode on the menu screen shown in FIG. 3 and presses the start button, the image of the placed document is read by the document reading unit 10. It is done. The image signal read by the document reading unit 10 is digitally processed by the image processing unit 110 and subjected to various processes such as screen processing, density correction, and magnification correction. When density correction is performed, density correction is performed using the correction value set in step SA16 described above. Then, color conversion processing is performed on the image signal that has been subjected to various types of processing, and is converted into image signals of Y (yellow), M (magenta), C (cyan), and K (black) colors. The image signals of each color of YMCK are output from the image processing unit 110 and input to the image forming unit 20 that forms an image. In the image forming unit 20, each color toner image is formed based on the image signal output from the image processing unit 110, and the toner image is transferred to the intermediate transfer belt 40. The toner image transferred to the intermediate transfer belt 40 is transferred onto the recording paper P by the secondary transfer roll 32 and the opposing roll 41. The recording paper P onto which the toner image has been transferred is heated and pressurized by the fixing device 60 and then sent again to the secondary transfer roll 32 by the transport rolls 81 and 82. Then, the recording paper P passes between the secondary transfer roll 32 and the opposing roll 41 without coming into contact with the intermediate transfer belt 40, and is placed on the fixing device 60. The recording paper P is heated and pressurized again by the fixing device 60 and then discharged to the discharge tray 70.

  As described above, according to the present embodiment, it is possible to detect the density of images having different fixing times without being affected by the image formed on the back surface. Since the correction value of the image density corresponding to the number of fixing times is obtained based on the detected density, the density difference caused by the difference in the number of fixing times can be accurately corrected.

When an image is formed on both sides of a recording sheet in the image forming apparatus described above, a correction value (correction value obtained in step SA16) for correcting the image density to a target density at the time of fixing twice is used. Thus, the image density correction may be performed.
In addition, when images are formed on both sides of a recording sheet and the glossiness of the images on both sides is increased, the fixing process is performed three times on the front surface and the fixing process is performed twice on the back surface. The test pattern is fixed three times, the image subjected to the three fixing processes is read to obtain a density correction value, images are formed on both sides of the recording paper, and the glossiness of the images on both sides is increased. In the case of increasing the density, the density correction of the image may be performed with the obtained correction value. Further, the recording paper that has been fixed once and the recording paper that has been fixed twice may be discharged to the same discharge tray.

[Second Embodiment]
[Constitution]
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 5 is a configuration diagram of an image forming apparatus according to the second embodiment of the present invention. The image forming apparatus according to the present embodiment is different from the image forming apparatus according to the first embodiment in that two fixing devices are provided. Since other configurations are the same as those of the image forming apparatus according to the first embodiment, the same reference numerals are given to the same portions as those of the first embodiment in FIG. 5 and description thereof is omitted.

  As shown in FIG. 5, the image forming apparatus includes a fixing device 60A and a fixing device 60B. When the image forming apparatus forms an image on one side of the recording paper P and performs a single fixing process, the recording paper P on which an image is formed by heating and pressurizing by the fixing device 60A is placed on the discharge tray 70. Discharge. Further, when the image forming apparatus performs image formation on both sides of the recording paper P, the recording paper P heated and pressed by the fixing device 60A and fixed on the image is switched back by the conveying roll 80, It is sent again to the secondary transfer roll 32 by the transport rolls 81 and 82. Then, the recording paper P on which images are formed on both sides is discharged to the discharge tray 70 via the secondary transfer roll 32 and the fixing device 60A. Further, when an image is formed on one side of the recording paper P and the fixing process is performed twice, the recording paper P is sent to the fixing device 60B without performing switchback. Then, the second heating / pressurization is performed by the fixing device 60 </ b> B, and the recording paper P on which the second fixing process has been performed is discharged to the discharge tray 71.

[Operation]
Next, the operation of this embodiment will be described.
After the touch panel is operated and the menu screen for image quality correction (see FIG. 3) is displayed,
The user touches the touch panel and selects one of the standard image quality / high image quality, plain paper / thick paper, and printer / copy modes for each of the image quality, paper type, and screen items.
Next, when the user performs an operation of touching the “image quality correction” portion of the touch panel shown in FIG. 3, the control unit 100 controls the image forming unit 20, and as shown in FIG. An image of a test pattern having a different tone is transferred to the recording paper P (step SB1). When the image forming unit 20 forms an image on the recording paper P, the image processing unit 110 performs screen processing in the screen mode selected by the user on the test pattern image.

  When the transfer of the test pattern is completed, the control unit 100 sends the recording paper P to the fixing device 60A. The recording paper P sent to the fixing device 60A is heated and pressurized by the fixing device 60A (step SB2). Next, when the image quality mode selected by the user is the standard image quality (step SB3; YES), the recording paper P on which the image is fixed is discharged to the discharge tray 70 (step SB4). On the other hand, when the image quality mode is high image quality (step SB3; NO), the recording paper P heated and pressurized by the fixing device 60A and having the image fixed thereon is sent to the fixing device 60B (step SB5). Then, the recording paper P that has been subjected to the second fixing process (step SB6) by the fixing device 60B is discharged to the discharge tray 71 (step SB7).

  Next, the user places the discharged recording paper P on the platen glass 12. Thereafter, when the user presses a start button provided on the image forming apparatus and instructs to read an image (step SB8; YES), the test pattern on the placed recording paper P is read by the document reading unit 10. (Step SB9). Next, the image forming apparatus detects the image density of the read test pattern (step SB10). Then, the detected image density is compared with the target density of the rectangular area of the test pattern stored in advance in the ROM, a correction value for correcting the image density to the target density is obtained, and the obtained correction value is stored. (Step SB11). Here, when the image quality / paper type / screen mode selected by the user is for standard image quality / plain paper / copy, the obtained correction value is stored as the standard image quality / plain paper / copy correction value. If the image quality, paper type, and screen modes selected by the user are for high image quality, plain paper, and copy, the correction values obtained are stored in the area on the RAM. Is stored in an area on the RAM for storing the correction value.

  After the correction value setting process is completed, the user places the document on the platen glass 12, and in the menu screen shown in FIG. 3, the items of image quality, paper type, and screen are “standard image quality” and “plain paper”. When “for copy” is selected and the start button is pressed, the image of the placed document is read by the document reading unit 10. The image signal of the image read by the document reading unit 10 is digitally processed by the image processing unit 110 and subjected to various processes such as screen processing, density correction, and magnification correction. At the time of density correction, density correction is performed using standard image quality / plain paper / copy correction values stored in the RAM. In the image processing unit 110, color conversion processing is performed on the image signal that has been subjected to various types of processing, and Y (yellow), M (magenta), C (cyan), and K (black) color images. Converted to a signal. The image signals of each color of YMCK are output from the image processing unit 110 and input to the image forming unit 20 that forms an image. In the image forming unit 20, each color toner image is formed based on the image signal output from the image processing unit 110, and the toner image is transferred to the intermediate transfer belt 40. The toner image transferred to the intermediate transfer belt 40 is transferred onto the recording paper P by the secondary transfer roll 32 and the opposing roll 41. The recording paper P to which the toner image has been transferred is heated and pressurized by the fixing device 60A and then discharged to the discharge tray 70.

  On the other hand, the user places an original on the platen glass 12, and selects “high quality”, “plain paper”, and “copy” for the image quality, paper type, and screen items on the menu screen shown in FIG. When the start button is pressed, the document reading unit 10 reads the image of the placed document. The image signal read by the document reading unit 10 is digitally processed by the image processing unit 110 and subjected to various processes such as screen processing, density correction, and magnification correction. At the time of density correction, density correction is performed using correction values for high image quality, plain paper, and copying that are stored in the RAM. In the image processing unit 110, color conversion processing is performed on the image signal that has been subjected to various types of processing, and Y (yellow), M (magenta), C (cyan), and K (black) color images. Converted to a signal. The image signals of each color of YMCK are output from the image processing unit 110 and input to the image forming unit 20 that forms an image. In the image forming unit 20, each color toner image is formed based on the image signal output from the image processing unit 110, and the toner image is transferred to the intermediate transfer belt 40. The toner image transferred to the intermediate transfer belt 40 is transferred onto the recording paper P by the secondary transfer roll 32 and the opposing roll 41. The recording paper P onto which the toner image has been transferred is heated and pressurized by the fixing device 60A and then sent to the fixing device 60B. Then, the recording paper P is heated and pressurized again in the fixing device 60B, and then discharged to the discharge tray 71.

  As described above, according to the present embodiment, it is possible to detect the density of images having different fixing times without being affected by the image formed on the back surface. Since the correction value of the image density corresponding to the number of fixing times is obtained based on the detected density, the density difference caused by the difference in the number of fixing times can be accurately corrected.

[Modification]
As mentioned above, although embodiment of this invention was described, this invention is not limited to embodiment mentioned above, It can implement with another various form. For example, the present invention may be implemented by modifying the above-described embodiment as follows.

  The image forming apparatus is not limited to the intermediate transfer system, but may be a system that directly transfers a toner image from a photosensitive drum to a recording sheet, or a toner jet system that sprays toner directly onto a recording sheet. In addition, the image forming apparatus is not limited to a tandem configuration, and may be a black single color or a rotary development type. The document reading unit may be externally attached to the image forming apparatus. Further, the test pattern is not limited to those stored in advance in the image forming apparatus, but may be input from an external apparatus. The test pattern may be provided with characters or marks so that the case where the fixing process is performed once and the case where the fixing process is performed twice can be distinguished.

  In the embodiment described above, an image of the test pattern placed on the platen glass is determined, and when detecting the density of the image, it is determined whether the test pattern is in an appropriate position or whether the direction of the test pattern is appropriate. If it is not appropriate, a warning may be displayed.

In the above-described embodiment, the image signal output from the document reading unit 10 is converted into data in the L ^* a ^* b ^* color space by the image processing unit 110 and then converted from the data in the L ^* a ^* b ^* color space to YMCK. If the image signal is generated and the image density correction is performed,
The density of the YMCK image may be corrected when the YMCK image signal is generated from the L ^* a ^* b ^* color space data. Further, in each aspect described above, the image quality may be corrected by controlling the fixing temperature, the fixing time, and the like. In each of the above-described aspects, the charging potential of the photosensitive drum, the developing bias potential, the rotation speed of the developing roller, the exposure amount of the photosensitive drum, the toner density in the developing device, and the like are controlled to correct the image quality. It may be. Further, in each aspect described above, the glossiness of the read image may be obtained, and the fixing temperature and the fixing time may be controlled based on the obtained glossiness.

  When the recording paper is heated and pressurized by fixing, the toner image transferred to the recording paper becomes larger than the original size transferred as the recording paper expands. Accordingly, in each of the above-described aspects, the image of the image that has been stretched by being heated and pressurized by fixing is determined based on the size of the test pattern image stored in advance and the size of the test pattern image read by the document reading unit 10. When obtaining an enlargement factor and copying an image, the size of the image is corrected based on the enlargement factor, and the image size is determined between the original document to be copied and the image output from the image forming apparatus. There may be no difference.

  In each aspect described above, a sensor for reading an image may be provided in the vicinity of the fixing device, and a test pattern formed on the recording paper may be read when the fixing is completed.

1 is a schematic view of an image forming apparatus according to a first embodiment of the present invention. 3 is a flowchart showing a processing flow of the image forming apparatus according to the first embodiment. 3 is a diagram illustrating a menu screen displayed on the image forming apparatus. FIG. FIG. 6 is a diagram illustrating a test pattern output from the image forming apparatus. It is the schematic of the image forming apparatus which concerns on 2nd Embodiment of this invention. 9 is a flowchart illustrating a processing flow of an image forming apparatus according to a second embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 .... Document reading unit, 11 ... Light source, 12 ... Platen glass, 13 ... Reflection mirror, 14 ... Lens, 15 ... Solid-state image sensor, 20 ... Image formation part, 31 ... Primary transfer roll, 32 ... Secondary transfer roll, 33 ... Belt cleaner, 34 ... Photoconductor drum, 35 ... Charger, 36 ... Exposure unit, 37 ... Development 38, cleaning device, 39 ... toner cartridge, 40 ... intermediate transfer belt, 41, 42 ... opposite roll, 50, 51, 52 ... paper tray, 60, 60A, 60B ..Fixing device, 70, 71 ... discharge tray, 100 ... control unit, 110 ... image processing unit.

Claims (7)

A test image transfer process for transferring a toner image of a predetermined test image to one side of the recording medium;
The toner image transferred to the recording medium by the test image transfer process, a test image fixing process for fixing before type recording medium in the second fixing times that is the first fixing times or setting that is set,
And the toner image of the test image fixed before type recording medium in the first fixing times, the process of reading reads the toner image of the test image fixed on the recording medium in the second fixing times,
A density detection process for detecting the density of each toner image read by the reading process;
As the concentration of being transferred to a recording medium the toner image is fixed by the first fixing count reaches the target predetermined concentration, an image forming condition of the toner image, it is detected Oite the concentration detecting step The density of the toner image of the test image fixed at the first fixing number is set according to the density of the toner image transferred to the recording medium and fixed at the second fixing number. A setting process for setting the image forming condition of the toner image according to the density of the toner image of the test image fixed at the second fixing number detected in the density detection process;
An image input process in which an image is input;
A fixing number setting process for setting a fixing number of toner images of the image input in the image input process;
When fixing the toner image of the image input in the image input process on the recording medium with the first fixing number set in the fixing number setting process, the toner image is fixed at the first fixing number. The toner image of the image input in the image input process is formed according to the image forming conditions set in the setting process according to the density of the toner image of the test image and transferred to a recording medium. When the toner image is fixed on the recording medium with the second fixing number set in step S2, the toner image is set in the setting process according to the density of the toner image of the test image fixed at the second fixing number. Image transfer process for forming and transferring to a recording medium according to the image forming conditions ,
An image forming method and an image fixing process for fixing before type recording medium by the number of times the image transfer toner image formed on the recording medium by a process, set in the fixing times setting process. Transferred to the recording medium, wherein as the concentration of the fixed toner image by fixing the number of times set by the fixing number setting process is goals concentration, in accordance with the detected density by the density detection process, the image fixing The image forming method according to claim 1, wherein a fixing temperature and a fixing time in the process are controlled. Transferred to the recording medium, wherein as the concentration of the fixed toner image by fixing the number of times set by the fixing number setting process is goal concentration, the amount of toner transferred to the recording medium in the image transfer process, The image forming method according to claim 1, wherein the image forming method is controlled according to the density detected by the density detection process. Transferred to the recording medium, wherein as the concentration of the fixed toner image by fixing the number of times set by the fixing number setting process is goal density, the image input in the input step, detected by said concentration detecting step The image forming method according to claim 1, wherein correction is performed according to the density. The image transfer process includes:
A charging process for charging a photoconductive photoconductor;
Exposing the charged photoreceptor in accordance with an input image to form an electrostatic latent image; and
A toner image forming process in which toner is attached to the electrostatic latent image to form a toner image on the photoreceptor;
A transfer process for transferring the formed toner image to a recording medium,
Transferred to the recording medium, the density of the fixed toner image by fixing the number of times set by fixing the number of setting processes to become targets concentration, the charging potential of the photosensitive member, an exposure amount of the exposure, or the photosensitive The image forming method according to claim 1, wherein at least one of a developing bias potential for attaching toner on the body is corrected according to the density detected by the density detection process. A detection process for detecting the size of the toner image read by the reading process;
An enlargement ratio calculating step for obtaining an enlargement ratio of the toner image read by the reading step with respect to the test image from the size of the toner image detected by the detection step and the size of the test image;
Transferred to the recording medium, the size of the fixed toner image by fixing the number of times set by the fixing number setting process, so that the size of the input image and substantially the same size, the size of the input image An image correction process for correcting the image according to the enlargement ratio obtained by the enlargement ratio calculation process,
With
The image forming method according to claim 1, wherein in the image transfer process, a toner image is formed on a recording medium in accordance with the image whose size is corrected by the image correction process. Two fixing means for fixing the toner image transferred to the recording medium by heating and pressing the recording medium ;
In the test image fixing process and the image fixing process, when the number of times of fixing is one, the toner image transferred to the recording medium is fixed to the recording medium by one fixing unit, and the number of times of fixing is two. case, the image forming method according to claim 1, characterized in Rukoto to fix the toner image transferred to the recording medium to the recording medium at two fixing means.

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